The Structure of Secondary 2-Azidoethanamines: 

A Hypergolic Fuel vs. a Nonhypergolic Fuel 

by Michael J. McQuaid 

ARL-TR-3176 April 2004 

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Army Research Laboratory 

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ARL-TR-3176 April 2004 

The Structure of Secondary 2-Azidoethanamines: 

A Hypergolic Fuel vs. a Nonhypergolic Fuel 

Michael J. McQuaid 

Weapons and Materials Research Directorate, ARL 

Approved for public release; distribution is unlimited. 
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The Structure of Secondary 2-Azidoethanamines: 

A Hypergolic Fuel vs. a Nonhypergolic Fuel 

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Michael J. McQuaid 

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14. ABSTRACT 

In an attempt to find structural features of 2-azidoethanamines that correlate with their hypergolic ignition delays, density 

functional theory (DFT)-based quantum mechanics calculations were performed to characterize equilibrium configurations of 

two secondary 2-azidoethanamines: 2-azido-N-cyclopropylethanamine (CPAZ) and 2-azido-N-methylethanamine (MMAZ). 

The former is hypergolic with inhibited red fuming nitric acid, while the latter is not. Geometries and normal modes for 23 

MMAZ conformers and 42 CPAZ conformers are presented, compared to each other, and compared to geometries and normal 

modes obtained previously for the hypergolic, tertiary 2-azidoethanamine 2-azido-N,N-dimethylethanamine (DMAZ). The 

geometries of >N-CH2-CH2-N3 chains in analogous MMAZ and CPAZ conformers are found to be nearly identical, and the 

relative energies of MMAZ conformers as a function of this chain’s orientation are mimicked in the CPAZ conformers. Some 

minor differences between the secondary 2-azidoethanamines and DMAZ are noted, but no structural feature is found to be 

unique to the hypergolic compounds. 

15. SUBJECT TERMS

computational quantum chemistry, amine azide fuels, hypergolic ignition delay 

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Michael J. McQuaid 

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iii

Contents 

List of Figures iv

List of Tables iv

1. Introduction 1

2. Computational Methods 3

3. Results 4

3.1 MMAZ.............................................................................................................................4 

3.2 CPAZ...............................................................................................................................8 

4. Discussion 18

5. Conclusions 19

6. References 20

Appendix. Geometric Parameters and Normal Mode Frequencies for 2-Azido-NMethylethanamine (MMAZ) and 2-Azido-N-Cyclopropylethanamine (CPAZ) 22

Distribution List 37 
iv

List of Figures 

Figure 1. DMAZ conformers A, B, and D. B is the lowest energy DMAZ conformer. 

Labeling follows a previous reference (McQuaid et al., 2002). ................................................3 

Figure 2. MMAZ group 1 conformers. ...........................................................................................5

Figure 3. MMAZ group 2 conformers. ...........................................................................................6

Figure 4. CPAZ group 11 conformers. .........................................................................................10

Figure 5. CPAZ group 21 conformers. .........................................................................................11

Figure 6. CPAZ group 12 conformers. .........................................................................................12

Figure 7. CPAZ group 22 conformers. .........................................................................................13

Figure 8. CPAZ group 13 conformers. .........................................................................................14

List of Tables 

Table 1. MMAZ equilibrium conformer B3LYP/6-311++G(d, p) energies and conformer 

probabilities in a gas-phase population at 298 K.......................................................................7 

Table 2. The relative energies of MMAZ equilibrium conformers by group and in 

comparison to the relative energies of DMAZ equilibrium conformers....................................8 

Table 3. Comparison of bond lengths (Å) in equilibrium conformers of MMAZ and DMAZ. .....9 

Table 4. The relative energies of CPAZ equilibrium conformers and conformer probabilities 

for a gas-phase population at 298 K. .......................................................................................15 

Table 5. The relative energies of CPAZ equilibrium conformers by group and in comparison 

to DMAZ and MMAZ equilibrium conformers.......................................................................15 

Table 6. Comparison of MMAZ and CPAZ equilibrium conformer geometries. ........................16 

Table 7. Comparison of MMAZ and CPAZ normal modes (cm-1)...............................................17 

Table A-1. Geometric parameters for MMAZ group 1 conformers. ............................................23 

Table A-2. Geometric parameters for MMAZ group 2 conformers. ............................................24 

Table A-3. Normal mode frequencies (cm-1) for MMAZ group 1 conformers. ...........................25 

Table A-4. Normal mode frequencies (cm-1) for MMAZ group 2 conformers. ...........................26 

Table A-5. Geometric parameters for CPAZ group 11 conformers. ............................................27 

Table A-6. Geometric parameters for CPAZ group 21 conformers. ............................................28 

Table A-7. Geometric parameters for CPAZ group 12 conformers. ............................................29 
v

Table A-8. Geometric parameters for CPAZ group 22 conformers. ............................................30 

Table A-9. Geometric parameters for CPAZ group 13 conformers. ............................................31 

Table A-10. Normal mode frequencies (cm-1) for CPAZ group 11 conformers. .........................32 

Table A-11. Normal mode frequencies (cm-1) for CPAZ group 21 conformers. .........................33 

Table A-12. Normal mode frequencies (cm-1) for CPAZ group 12 conformers. .........................34 

Table A-13. Normal mode frequencies (cm-1) for CPAZ group 22 conformers. .........................35 

Table A-14. Normal mode frequencies (cm-1) for CPAZ group 13 conformers. .........................36 
vi

INTENTIONALLY LEFT BLANK. 
1

1. Introduction 

The U.S. Army is developing a laser-guided 2.75-in rocket system for use on the AH-64 Apache, 

OH-58 Kiowa Warrior, and RAH-66 Comanche helicopters. Called the Advanced Precision Kill 

Weapon System (APKWS), the need for this system was identified in Desert Storm after-action 

investigations. Those investigations revealed that a large number of HELLFIRE (anti-tank 

missile) firings were made against soft- or lightly armored targets that could have been killed by 

a smaller weapon. The HELLFIRE was employed, however, because its precision guidance 

capability was needed to reduce the potential for collateral damage or fratricide. The APKWS is 

being designed to enhance the existing (unguided) Hydra-70 2.75-in rocket system and to 

complement the HELLFIRE. It will be the weapon of choice for operations in urban terrain or 

for aerial fire support missions in close proximity to friendly forces. 

Among technologies being considered for insertion into the APKWS is the Impinging Stream 

Vortex Engine (ISVE). Under development at the U.S. Army Aviation and Missile Research 

Development and Engineering Center (AMRDEC), it is thought capable of yielding a hypergolic 

propulsion system compact enough to fit in the APKWS. So equipped, the thrust of the APKWS 

could be controlled, increasing the engagement stand-off distances allowed and therefore 

improving platform survivability. 

Toward optimizing the ISVE’s design, the U.S. Army Research Laboratory (ARL) is simulating 

ISVE performance as a function of various design parameters via a computational fluid 

dynamics (CFD) model of the engine (Nusca and Michaels, 2003). In support of the effort, 

computational chemistry is being employed to estimate various (unmeasured) properties of 

candidate fuels. Needed as model input, to date, the emphasis has been on characterizing 

potential alternatives to the best current ISVE fuel candidate—monomethylhydrazine (MMH). 

Acutely toxic and a suspected carcinogen (Schmidt, 2001), MMH’s use requires the 

implementation of costly and burdensome handling procedures. 

Compounds with 2-azidoethanamine chains (>N-CH2-CH2-N3) comprise a class of fuels that 

AMRDEC has tested in the ISVE (and has investigated for use in other propulsion applications). 

Collectively referred to as Competitive Impulse Non-Carcinogenic Hypergols (CINCH) 

(Thompson et al., 1998; Stevenson, 2002), the formulation within this class of compounds 

receiving the most attention is 2-azido-N,N-dimethylethanamine [(CH3)2NCH2CH2N3]. Also 

referred to as DMAZ, it has been found to yield specific impulse competitive with MMH in 

inhibited red fuming nitric acid (IRFNA) oxidized systems, and it is much less toxic than 

hydrazine or its derivatives. Unfortunately, DMAZ-IRFNA systems have longer ignition delays 

than MMH-IRFNA systems. Increasing ignition delays result in more fuel and oxidizer 

accumulating in the combustion chamber during engine start up, and to avoid overpressurizing 

the chamber when the accumulation finally ignites, a larger chamber must be designed. 
2

Penalizing rocket performance, this issue may negatively impact the U.S. Army’s ability to field 

DMAZ or other CINCH fuels. 

Compromised ignition delays are a common problem with hydrazine-alternative hypergols, and a 

mechanistic understanding of CINCH-IRFNA ignition processes is being sought in the hope of 

addressing the issue. Based on traditional chemical insight, and finding amine nitrate salts in the 

residue of DMAZ-IRFNA combustion experiments, AMRDEC has hypothesized that proton 

transfer from nitric acid to the fuel’s amine nitrogen may be a rate-controlling step. Therefore, 

one of AMRDEC’s approaches to addressing the ignition delay issue has been to attempt to 

enhance the amine’s reactivity/basicity by replacing the methyl groups in DMAZ with other 

substituents. Two secondary amine azides synthesized on this basis were 2-azido-Nmethylethanamine (MMAZ) and 2-azido-N-cyclopropylethanamine (CPAZ), and the results 

were mixed. MMAZ, which has a hydrogen atom in lieu of one of the methyl groups in DMAZ, 

is not hypergolic. CPAZ, which has a cyclopropyl group in lieu of the methyl group in MMAZ, 

has an ignition delay comparable to DMAZ (Stevenson, 2002). Given the hypothesized 

importance of base strength, the result for MMAZ is surprising because its base strength (based 

on measured pKa) is higher than DMAZ’s. 

In a first step toward trying to reconcile such observations via computational chemistry, ARL 

determined the nature of equilibrium DMAZ conformers (McQuaid et al., 2002). Twelve 

conformers were identified via density functional theory (DFT) calculations, and an analysis of 

an infrared (IR) absorption spectrum of DMAZ vapor at 298 K supported the computed 

differences in their energy. An interesting finding of the study was that in its lowest energy 

configuration, which is shown in Figure 1, the azide group shields the amine lone pair electrons 

from proton attack. Given the expected importance of proton transfer to the amine site, the 

finding suggested the possibility of molecular geometry being a factor controlling the onset of 

ignition. 

Based on its computed electron density distribution, the energy of the “shielded” DMAZ 

conformer (B) appears to be lowered by an attractive interaction between a slightly positive 

partial charge on the middle nitrogen of the azide group (N3) and a slightly negative partial 

charge associated with the amine nitrogen (N1). Comparing the calculated energies of DMAZ 

conformers B and A, structures whose only significant difference is their C3-C4-N2-N3 dihedral 

angle, the attraction appears to lower B’s energy by ~1 kcal/mol. Given this observation, a 

concern about the potential benefit of increasing the basicity of the amine nitrogen is raised. 

That is, should an increase in amine basicity lead to an increase in the attraction between the 

amine and azide groups, it might lead to a greater percentage of molecules in a population 

assuming a shielded configuration, offsetting the (presumed) benefit of the increased basicity. 

A stereoisomer-based approach for designing molecules that preclude (or promote) a shielded 

configuration in amine azides has been proposed, and a theoretical study of an embodiment of 

the approach, namely 2-azido-N,N-dimethylcyclopropanamine (ADMCPA), suggests its promise
3

Figure 1. DMAZ conformers A, B, and D. B is the lowest energy DMAZ conformer. Labeling follows a 

previous reference (McQuaid et al., 2002). 

(McQuaid, 2002). However, until molecules designed in this manner are synthesized and tested, 

the impact of shielding on the ignition process is likely to remain uncertain. In the interim, the 

differences (and similarities) between DMAZ, MMAZ, and CPAZ suggested that a comparison 

of their structures might identify differences that correlate with ignition delay. Further 

motivating this study was an investigation that shows that the proton affinities of azide lone pair 

sites are significantly higher than analogous sites in ethyl azide, and that this effect is passed 

from/through the ethyl chain (McQuaid, 2003). Therefore, a comprehensive survey to identify 

and characterize equilibrium conformers of MMAZ and CPAZ was completed. This report 

summarizes the findings of the study, with previously reported results for DMAZ provided for 

comparison. 

2. Computational Methods 

The Gaussian 98 (G98) suite of quantum chemistry codes (Frisch et al., 2001) was employed to 

identify equilibrium MMAZ and CPAZ conformers and characterize their normal modes. The 

choice of model—B3LYP functionals (Becke, 1993; Lee et al., 1988) and a 6-311++G(d,p) 

atomic orbital basis set (Miehlich et al., 1989; Clark et al., 1983; McLean and Chandler, 1980; 

Krishnan et al., 1980) on the G98-defined “ultrafine” integration grid—was based on its success 

in characterizing DMAZ (McQuaid et al., 2002). The search for equilibrium conformers did 

not extend much beyond finding DMAZ “analogs,” i.e., structures with the dihedral angle 

preferences observed in DMAZ. However, the author expects that most (if not all) of the lowest 

energy structures will prove to have been identified by this approach. Because the results are not 

compared to experimental IR data, no scaling to correct potential systematic bias in the normal 

mode frequency calculations was performed. 

 A B D 

N4 N3 

H2 

H1 

H3 

C3 

H5 

H6 

C2 

C1 

H8 

N2 

H9 

H10 

H4 

C4 

N1 

H7 
4

3. Results 

3.1 MMAZ 

Figures 2 and 3 show the 23 unique MMAZ equilibrium structures identified through the study. 

(A total of 24 structures are given in Figures 2 and 3, but conformers I1 and I2 are mirror images 

of one another.) A complete description of each conformer’s geometry and normal mode 

frequencies is given in the appendix. The conformers are distinguished by their dihedral angles, 

and conformer labels were chosen to facilitate comparison with the DMAZ conformers identified 

and described in a previous publication (McQuaid et al., 2002). The labeling scheme for DMAZ 

conformers in that publication was chosen such that alphabetically adjacent conformers are 

nominally transformed into one another by a dihedral angle rotation about either the N(amine)-

C(ethyl), C-C or C-N(azide) bond. The letter designation for an MMAZ conformer indicates the 

correspondence of its C-N(H)-CH2-CH2-N3 orientation with that of the same-lettered DMAZ 

conformer. 

To further facilitate comparisons with DMAZ, the structures are divided into two groups. In the 

first group, which is shown in Figure 2, the C1-N1-C2-C3, N1-C2-C3-N2, and C2-C3-N2-N3 

dihedral angle combinations correspond to the C1-N1-C3-C4, N1-C3-C4-N2, and C3-C4-N2-N3 

dihedral angle combinations of DMAZ. In this group, all but one counterpart to observed 

DMAZ conformers are found. Attempts to find the missing one, i.e., the analog to DMAZ 

conformer K, were conducted via optimizations started with geometries like the one 

hypothesized. But the optimizations led to either J1 or L1. In the second group, which is shown 

in Figure 3, the C1-N1-C2-C3, N1-C2-C3-N2, and C2-C3-N2-N3 dihedral angle combinations 

correspond to C2-N1-C3-C4, N1-C3-C4-N2, and C3-C4-N2-N3 dihedral angle combinations of 

DMAZ. In this group, analogs to all of the DMAZ conformers are found. One without a 

corresponding DMAZ conformer was also identified. Except for its C2-C3-N2-N3 dihedral 

angle, this “new” conformer is nominally the same as conformers C2 and D2 and is therefore 

placed between them in Figure 3. It is labeled X2 to avoid the need to change other labels. 

Table 1 provides MMAZ conformer zero-point corrected energies (ZPE), the difference between 

their ZPE and the ZPE of the lowest energy conformer (∆E), and two estimates of their 

probability (W) in a gas-phase sample at T = 298 K, 

= −∆ ∑ −∆

i

i i i W exp( . (1) E / kT)/ exp( E / kT)

The first conformer population distribution is based on ∆Ei’s calculated from uncorrected ZPE 

values. In the second distribution, the ∆Ei are calculated assuming a C2-C3-N2-N3 dihedral 

angle-related bias in the energy calculations. To account for this bias, which was identified in 

the study of DMAZ reported previously (McQuaid et al., 2002), the ZPEs of “anti” conformers 

(i.e., those with C2-C3-N2-N3 dihedral angles near 180°) are increased 0.000637 Hartrees
5

Figure 2. MMAZ group 1 conformers. 

relative to “gauche” conformers (i.e., those with C2-C3-N2-N3 dihedral angles near (±)80°). It 

is observed that, except for A1 and A2, group 1 conformers are lower in energy than their group 

2 counterparts. Somewhat surprisingly, the 2 lowest energy conformers of the entire set, i.e., 

D1 and C1, are not counterparts to the lowest energy DMAZ structure (B). D1 and C1 are

 A1 B1 C1 

 D1 E1 F1 

 G1 H1 I1 

 J1 L1 

 N4 

N3 

N2 

H8 

H7 

C3 

H6 

C2 

H5 

H3 

C1 

H2 H4 

H1 N1 
6

Figure 3. MMAZ group 2 conformers. 

configurations in which the azide group does not shield amine site from proton attack, and they 

are predicted to have a combined population exceeding 50% of the total in a room temperature 

vapor sample. The probability of shielded MMAZ configurations (B1 and B2) in the same 

 A2 B2 C2 X2 

 D2 E2 F2 

 G2 F2 I2 

 J2 K2 L2 

H1 

H2 

H5 

H3 

H4 

H6 

H7 

H8 

N1 

C1 

C3 

N2 

N3 

N4 

C2 
7

Table 1. MMAZ equilibrium conformer B3LYP/6-311++G(d, p) energies and 

conformer probabilities in a gas-phase population at 298 K. 

Conformer ZPE 

(Hartrees)

∆E

(kcal/mol)

W W 

(adj.)a

D1 –338.0384 0.0 0.44 0.32 

C1 −338.0373 0.7 0.13 0.19 

B1 −338.0366 1.1 0.06 0.09 

E1 −338.0365 1.2 0.06 0.08 

F1 −338.0365 1.2 0.06 0.04 

J1 −338.0365 1.2 0.06 0.04 

B2 −338.0362 1.4 0.04 0.06 

G1 −338.0358 1.7 0.03 0.04 

E2 −338.0357 1.7 0.02 0.02 

L1 −338.0353 2.0 0.02 0.02 

F2 −338.0351 2.1 0.01 0.02 

G2 −338.0350 2.1 0.01 0.02 

D2 −338.0349 2.2 0.01 0.01 

A2 −338.0348 2.3 0.01 0.01 

I1/I2 −338.0346 2.4 0.01 0.01 

X2 −338.0345 2.4 0.01 0.01 

C2 −338.0342 2.7 0.00 0.01 

H1 −338.0342 2.7 0.00 0.01 

H2 −338.0341 2.7 0.00 0.01 

A1 −338.0339 2.8 0.00 0.01 

J2 −338.0336 3.0 0.00 0.00 

L2 −338.0333 3.2 0.00 0.00 

K2 −338.0329 3.5 0.00 0.00 a

 Population distribution obtained if the ZPEs of anti conformers (D, E, I, and J) are increased 

0.000627 Hartrees to account for the suspected bias (vs. gauche conformer ZPEs) in their 

calculated values. 

sample is predicted to be between 9% and 15%. In room temperature DMAZ vapor, the shielded 

conformation was observed to be present in ~45% of the total population. 

Table 2 shows the ZPEs of the MMAZ conformers relative to the ZPE of the B conformer in 

their group and compares them to the relative energies of the DMAZ conformers. (The values 

are not corrected for the suspected bias in the calculation of anti and gauche conformer ZPEs.) 

The comparison shows that the ZPE differences between the DMAZ conformers are mimicked in 

MMAZ group 2, but not in MMAZ group 1. At first glance, the proximity of the amine-bonded 

hydrogen (H4) and the azide nitrogen (N2) in conformer D1 suggests the possibility of an 

intramolecular hydrogen bond, which in turn might account for the unexpectedly low energy of 

this conformer. However, the N1-H4-N2 angle (102°) and the lack of a significant shift in the 

(Mode 39) N1-H4 stretching frequency (relative to other group 1 conformers) deny the existence 

of a classic hydrogen bond. The table also shows that, as found for DMAZ, the proximity of the 

amine and azide groups in the B conformer appears to lower its energy relative to the A 

conformer, the difference being 1.7 kcal/mol in group 1 and 0.9 kcal/mol in group 2. 
8

Table 2. The relative energies of MMAZ equilibrium 

conformers by group and in comparison to the 

relative energies of DMAZ equilibrium 

conformers. 

∆E (kcal/mol) 

Conformer DMAZ 

MMAZ 

Group 1 

MMAZ 

Group 2 

A 1.2 1.7 0.9 

B 0.0 0.0 0.0 

C 1.3 –0.4 1.3 

X a a 1.1 

D 1.0 –1.1 0.8 

E 0.4 0.1 0.3 

F 0.8 0.1 0.7 

G 0.9 0.5 0.8 

H 1.9 1.5 1.3 

I 1.6 1.3 1.0 

J 2.0 0.1 1.6 

K 2.4 a 2.1 

L 2.2 0.8 1.9 a

 Searched for, but not observed. 

Table 3 compares the lengths of MMAZ and DMAZ bonds. No significant differences are 

observed in the bond lengths of analogous conformers. If the lowest energy structures of each 

molecule are compared, some larger differences are observed. For example, MMAZ conformer 

D1 has a 0.012 Å shorter C-C bond and a 0.010 Å longer C-N(azide) bond than DMAZ 

conformer B. But such differences indicate that there is little difference in the bond strengths of 

the two conformers. (For reference, the C=C double bond in ethene is 0.22 Å shorter than the 

C-C single bond in ethane.) Moreover, as will be shown in the next section, the conformer 

dependence of MMAZ bond lengths is also found in (the hypergolic) CPAZ. 

3.2 CPAZ 

The substitution of the methyl group in MMAZ with the (rigid) cyclopropyl ring found in CPAZ 

introduces a 3-fold increase in the number of conformers that can be hypothesized based on 

observed geometric preferences. Though steric hindrance will undoubtedly (and does) reduce 

the number of molecular configurations to less than the 81 (34

) that are calculated assuming three 

possible dihedral angles about four different bonds, the experience with MMAZ suggested that 

something close to this number would be found. Coupled with the longer calculation times 

needed for the four extra atoms, the author decided not to attempt to establish the existence of 

every equilibrium conformer that can hypothesized. Rather, a search for all of the conformers 

corresponding to the seven lowest energy structures of DMAZ was conducted first. It 

established that, as in the case of ADMCPA (McQuaid, 2002), an amine lone pair-cyclopropyl 
9

Table 3. Comparison of bond lengths (Å) in equilibrium conformers of 

MMAZ and DMAZ. 

MMAZ 

Parameter 

MMAZ 

B1 

DMAZ 

B 

MMAZ 

D1 

DMAZ 

D 

DMAZ 

Parametera

H1-C1 1.093 1.092 1.094 1.093 H1-C1 

H2-C1 1.092 1.093 1.092 1.093 H2-C1 

H3-C1 1.103 1.106 1.103 1.106 H3-C1 

C1-N1 1.460 1.458 1.459 1.459 C1-N1 

N1-C2 1.456 1.459 1.455 1.461 C3-N1 

C2-C3 1.528 1.531 1.519 1.526 C4-C3 

H5-C2 1.106 1.107 1.105 1.106 H7-C3 

H6-C2 1.094 1.093 1.096 1.094 H8-C3 

C3-N2 1.476 1.476 1.486 1.485 N2-C4 

H7-C3 1.098 1.096 1.096 1.097 H9-C4 

H8-C3 1.091 1.091 1.095 1.095 H10-C4 

N2-N3 1.230 1.230 1.228 1.228 N3-N2 

N3-N4 1.134 1.134 1.135 1.136 N4-N3 

MMAZ 

Parameter

MMAZ 

B2 

DMAZ 

B 

MMAZ 

D2 

DMAZ 

D 

DMAZ 

Parametera

H1-C1 1.093 1.092 1.089 1.088 H4-C2 

H2-C1 1.092 1.092 1.092 1.093 H5-C2 

H3-C1 1.103 1.106 1.103 1.106 H6-C2 

C1-N1 1.459 1.458 1.464 1.462 C2-N1 

N1-C2 1.457 1.459 1.461 1.461 C3-N1 

C2-C3 1.532 1.531 1.525 1.526 C4-C3 

H5-C2 1.105 1.107 1.103 1.106 H7-C3 

H6-C2 1.093 1.093 1.094 1.094 H8-C3 

C3-N2 1.475 1.476 1.485 1.485 N2-C4 

H7-C3 1.096 1.096 1.097 1.097 H9-C4 

H8-C3 1.091 1.091 1.095 1.095 H10-C4 

N2-N3 1.230 1.230 1.227 1.228 N3-N2 

N3-N4 1.135 1.134 1.136 1.136 N4-N3 a

 DMAZ conformer and atom labels as well as bond lengths are from a previous 

reference (McQuaid et al., 2002). 

group orientation where the lone pair electrons point over the C1-C2 bond is energetically 

favored. Therefore, the search for analogs of the five remaining DMAZ structures was limited to 

finding conformers with this amine lone pair-cyclopropyl group orientation. 

Figures 4–8 show the equilibrium CPAZ structures identified by the search. The labeling 

follows that employed for DMAZ and MMAZ, with the letter designating a dihedral angle 

combination of the >NH-CH2-CH2-N3 chain in common with similarly lettered MMAZ and 

DMAZ conformers, and the first number being a group designation associating it with one of the 

two groups defined for MMAZ. The second number designates which of three nominal amine 
10

Figure 4. CPAZ group 11 conformers. 

 A11 B11 C11 

 D11 E11 F11 

 G11 H11 I11 

 J11 L11 

N4 

N3 

H2 

H1 

H3 

C3 

N1 

H5 

H6 

C2 

H7 

C1 

H8 

N2 

H9 

H10 

H4 

C5 

C4 
11

Figure 5. CPAZ group 21 conformers. 

 A21 B21 C21 

 D21 E21 F21 

 G21 H21 I21 

 J21 L21 

N4 

N3 

H2 

H1 H3 

C3 

N1 

H5 

H6 

C2 

H7 

C1 H8 

N2 

H9 

H10 

H4 

C5 

C4 
12

Figure 6. CPAZ group 12 conformers. 

lone pair-cyclopropyl group orientations the conformer has, with “1” corresponding to the 

energetically preferred orientation, “2” corresponding to the orientation next lowest in energy, 

and “3” designating the highest energy orientation. It will be noted that there are no “23” 

conformers. All attempts to establish such structures through optimizations started with the 

hypothesized combination ended up as a structure in another group. In all, 42 unique CPAZ 

structures were identified. (A total of 43 conformers are shown in Figures 4–8, but I11 and I21 

are mirror images of one another.) A complete description of their geometries and normal modes 

is provided in the appendix. 

 A12 B12 C12 

 D12 E12 F12 

 G12 

N4 

N3 

H2 

H1 

H3 

C3 

H5 N1 

H6 

C2 

H7 C1 

H8 

N2 

H9 

H10 

H4 

C5 

C6 
13

Figure 7. CPAZ group 22 conformers. 

CPAZ conformer ZPEs, their ZPEs relative to that of the lowest energy conformer (D11), and 

their predicted statistical weight in a gas-phase sample at 298 K are shown in Table 4. Like 

MMAZ, the group 1 conformers are lower in energy than their group 2 counterparts. The two 

lowest energy conformers correspond to group 11 configurations (D11 and C11), and over 95% 

of the conformers will have the energetically preferred H5-C3-N1-C4 dihedral angle found in 

groups 11 and 21. Less than 12% of all CPAZ conformers in a gas-phase sample at 298 K are 

expected to be in shielded configurations (B11 and B21). 

 A22 B22 C22 

 X22 D22 E22 

 F22 G22 

N4 

N3 

H2 

H1 

H3 

C3 

N1 

H5 

H6 

C2 

H7 

C1 

H8 

N2 

H9 

H10 

H4 

C4 

C5 
14

Figure 8. CPAZ group 13 conformers. 

Table 5 shows CPAZ group 11 and group 21 conformer ZPEs by group relative to the group’s 

B conformer. It also compares them to DMAZ and MMAZ (intragroup) ∆Es. The similarities 

between CPAZ group 11 and MMAZ group 1 conformer ∆Es are striking. Only the A-analog 

∆Es (CPAZ A11 vs. MMAZ A1) differ by more than 0.2 kcal/mol. Like MMAZ group 2 

conformers, the relative energies of the conformers found in group 21 follow those of their 

DMAZ analogs. 

 A13 B13 C13 

 D13 E13 F13 

 G13

N4 

N3 

H2 

H1 

H3 

C3 

N1 

H5 

H6 

C2 H7 

C1 

H8 

N2 

H9 

H10 

H4 

C4 

C5 
15

Table 4. The relative energies of CPAZ equilibrium conformers and conformer probabilities for a gas-phase 

population at 298 K. 

Conformer ZPE ∆E W W Conformer ZPE ∆E W W 

(Hartrees) (kcal/mol) (adj.)a

 (Hartrees) (kcal/mol) (adj.)a

D11 −415.4099 0.0 0.42 0.26 B12 −415.4050 3.1 0.00 0.01 

C11 −415.4088 0.7 0.13 0.17 B22 −415.4049 3.1 0.00 0.00 

J11 −415.4084 1.0 0.08 0.07 E12 −415.4049 3.1 0.00 0.00 

B11 −415.4082 1.1 0.07 0.10 D21 −415.4048 3.2 0.00 0.00 

E11 −415.4080 1.2 0.06 0.05 E22 −415.4045 3.4 0.00 0.00 

G11 −415.4073 1.6 0.03 0.04 C21 −415.4043 3.5 0.00 0.00 

F11 −415.4073 1.6 0.03 0.04 F12 −415.4042 3.6 0.00 0.00 

L11 −415.4072 1.7 0.02 0.04 G12 −415.4042 3.6 0.00 0.00 

B21 −415.4071 1.7 0.02 0.02 F22 −415.4039 3.7 0.00 0.00 

E21 −415.4070 1.8 0.02 0.03 G22 −415.4038 3.8 0.00 0.00 

I11/I21 −415.4066 2.1 0.01 0.01 D22 −415.4037 3.9 0.00 0.00 

F21 −415.4065 2.1 0.01 0.02 X22 −415.4035 4.0 0.00 0.00 

A11 −415.4064 2.2 0.01 0.02 C22 −415.4032 4.2 0.00 0.00 

G21 −415.4064 2.2 0.01 0.02 A12 −415.4032 4.2 0.00 0.00 

H21 −415.4062 2.3 0.01 0.02 D13 −415.4026 4.6 0.00 0.00 

H11 −415.4062 2.3 0.01 0.02 A22 −415.4018 5.1 0.00 0.00 

D12 −415.4059 2.5 0.01 0.01 C13 −415.4015 5.3 0.00 0.00 

C12 −415.4058 2.6 0.01 0.01 B13 −415.4008 5.7 0.00 0.00 

J21 −415.4057 2.6 0.01 0.01 E13 −415.4008 5.7 0.00 0.00 

A21 −415.4056 2.7 0.00 0.01 G13 −415.4000 6.2 0.00 0.00 

L21 −415.4054 2.8 0.00 0.01 F13 −415.4001 6.2 0.00 0.00 

— — — — — A13 −415.3989 6.9 0.00 0.00 a

 Population distribution obtained if the ZPEs of anti conformers (D, E, I, and J) are increased 0.000627 Hartrees to account 

for the suspected bias (vs. gauche conformer ZPEs) in their calculated values. 

Table 5. The relative energies of CPAZ equilibrium conformers by group and in 

comparison to DMAZ and MMAZ equilibrium conformers. 

Conformer DMAZ 

CPAZ 

Group 11 

MMAZ 

Group 1 

CPAZ 

Group 21 

MMAZ 

Group 2 

A 1.2 1.1 1.7 0.9 0.9 

B 0.0 0.0 0.0 0.0 0.0 

C 1.3 −0.4 −0.4 1.8 1.3 

X a a a a 1.1 

D 1.0 −1.1 −1.1 1.5 0.8 

E 0.4 0.1 0.1 0.0 0.3 

F 0.8 0.6 0.1 0.4 0.7 

G 0.9 0.6 0.5 0.5 0.8 

H 1.9 1.3 1.5 0.6 1.3 

I 1.6 1.0 1.3 0.3 1.0 

J 2.0 −0.1 0.1 0.9 1.6 

K 2.4 a a a 2.1 

L 2.2 0.7 0.8 1.1 1.9 a

 Searched for, but not observed. 
16

Table 6 compares the geometric parameters of CPAZ conformers B11 and D11 with those of 

MMAZ conformers B1 and D1. It is observed that except for parameters that include atoms of 

the methyl and cyclopropyl substituents, the differences between CPAZ B11 and MMAZ B1 and 

between CPAZ D11 and MMAZ D1 are negligible. Even the N(amine)-C(substituent) bond 

lengths are not that different, the C3-N1 bond in CPAZ conformers being only 0.02 Å shorter 

than the C1-N1 bond of their MMAZ analogs. 

Table 6. Comparison of MMAZ and CPAZ equilibrium conformer geometries. 

MMAZ MMAZ CPAZ MMAZ CPAZ CPAZ 

Parameter B1 B11 D1 D11 Parameter 

Bond Length (Å) 

H3-C1 1.103 1.093 1.103 1.093 H5-C3 

C1-N1 1.460 1.441 1.459 1.440 C3-N1 

N1-C2 1.456 1.459 1.455 1.459 N1-C4 

H4-N1 1.015 1.016 1.015 1.016 H6-N1 

C2-C3 1.528 1.528 1.519 1.519 C4-C5 

H5-C2 1.106 1.105 1.105 1.103 H7-C4 

H6-C2 1.094 1.093 1.096 1.095 H8-C4 

C3-N2 1.476 1.476 1.486 1.486 C5-N2 

H7-C3 1.098 1.098 1.096 1.096 H9-C5 

H8-C3 1.091 1.091 1.095 1.095 H10-C5 

N2-N3 1.230 1.230 1.228 1.228 N2-N3 

N3-N4 1.134 1.135 1.135 1.135 N3-N4 

Simple Angle (degrees) 

H3-C1-N1 114.0 116.9 113.9 116.9 H5-C3-N1 

C1-N1-C2 114.2 114.8 113.5 114.1 C3-N1-C4 

N1-C2-C3 111.3 111.2 111.1 111.0 N1-C4-C5 

H4-N1-C2 110.0 110.5 108.9 109.4 H6-N1-C4 

C2-C3-N2 113.2 113.2 108.4 108.5 C4-C5-N2 

H5-C2-C3 108.3 108.2 109.0 108.9 H7-C4-C5 

H6-C2-C3 108.6 108.9 108.0 108.2 H8-C4-C5 

C3-N2-N3 117.2 117.2 116.2 116.2 C5-N2-N3 

H7-C3-N2 110.5 110.4 109.6 109.6 H9-C5-N2 

H8-C3-N2 105.4 105.4 109.9 109.9 H10-C5-N2 

N2-N3-N4 171.8 171.9 173.9 173.9 N2-N3-N4 

Dihedral Angle (degrees) 

H3-C1-N1-C2 56.0 57.2 55.5 56.4 H5-C3-N1-C4 

C1-N1-C2-C3 170.0 168.8 −179.4 179.5 C3-N1-C4-C5 

N1-C2-C3-N2 −68.1 −68.0 64.8 64.6 N1-C4-C5-N2 

H4-N1-C2-C3 −66.0 −66.0 −56.3 −56.5 H6-N1-C4-C5 

C2-C3-N2-N3 80.3 81.3 −172.1 −172.0 C4-C5-N2-N3 

H5-C2-C3-N2 166.5 166.9 −60.4 −60.4 H7-C4-C5-N2 

H6-C2-C3-N2 50.8 50.9 −176.3 −176.5 H8-C4-C5-N3 

C3-N2-N3-N4 169.4 168.8 −178.8 −179.2 C5-N2-N3-N4 

H7-C3-N2-N3 −44.1 −43.1 67.8 67.9 H9-C5-N2-N3 

H8-C3-N2-N3 −160.0 −159.1 −52.0 −51.9 H10-C5-N2-N3 
17

Table 7 compares the normal modes of CPAZ conformer D11 with analogous modes in MMAZ 

conformer D1. (The comparability of modes was established by visual inspection of mode 

animations rendered by the graphical user interface GaussView.) For modes involving primarily 

the >N-CH2-CH2-N3 chain in each molecule, mode motions are similar, and their frequency 

differences tend to be less than 20 cm-1. One relatively large discrepancy is observed; namely, 

CPAZ mode 30 (1414 cm-1) vs. MMAZ mode 30 (1518 cm-1). But these modes involve motions 

that span the amine site. Moreover, they are only nominally similar, their equivalence in the 

table partly a consequence of specifying a 1-to-1 correspondence between MMAZ and CPAZ 

modes. Nominally a N1-H4 wag/C1-N1-C2 asymmetric stretch in MMAZ and a N1-H6 

wag/C3-N2-C4 asymmetric stretch in CPAZ, given the complexity and overlap of the modes in 

the frequency range from 1400 to 1520 cm-1 and the number of CPAZ modes that do not have a 

corresponding MMAZ mode, it is hard to imagine that this difference is a significant factor in the 

difference in ignition delay of these two compounds. 

Table 7. Comparison of MMAZ and CPAZ normal modes (cm-1). 

CPAZ CPAZ MMAZ MMAZ 

Mode D11 D1 Mode MMAZ (CPAZ) Mode Descriptiona

10 507 520 8 N1-C2-C3 bend 

11 558 556 9 N2-N3-N4 bend 

12 638 639 10 N2-N3-N4 bend 

14 785 781 11 N1-H4 rock 

15 821 839 12 CH2 rocks 

18 895 882 13 N1-H rock/C3-N2 stretch 

19 947 1005 14 — 

20 1004 1033 15 C1-N1 stretch/C2-C3 stretch 

24 1094 1081 16 — 

25 1131 1142 17 C1-N1 stretch/N1-C2-C3 asym. stretch 

26 1144 1161 18 C1-N1-C2 asym stretch 

27 1188 1195 19 N1-C2 stretch (C3-N1 stretch) 

29 1239 1245 20 CH2 wags 

31 1285 1305 21 CH2 wags 

32 1337 1338 22 C3-N2-N3 asym stretch 

33 1373 1376 23 CH2 wags 

34 1390 1402 24 CH2 wags 

36 1454 1458 25 C1H3 bend (C1H2 + C2H2 bends) 

37 1481 1481 26 C3H2 bend/N1-H4 wag 

38 1484 1487 27 C1H3 asym bend/N1-H4 wag 

39 1501 1495 28 — 

40 1511 1506 29 — 

30 1414 1518 30 N1-H4 wag/C1-N1-C2 asym stretch 

41 2238 2239 31 N2-N3-N4 asym stretch 

42 2940 2924 32 C2-H5 stretch (C4-H7 stretch) 

44 3038 2936 33 C1-H3 stretch (C3-H5 stretch) 

43 3010 3010 34 C3H2 sym stretch 

45 3054 3039 35 C2-H8 stretch (C4H2 asym stretch) 

— — 3047 36 C1-H stretches 

46 3058 3059 37 C3H2 asym stretch (C5H2 asym stretch) 

— — 3096 38 C1-H stretches 

51 3509 3522 39 N1-H4 stretch a

 Modes not described are relatively complex, defying convenient description.
18

4. Discussion 

One of the original reasons for undertaking this study was to assess the possibility that an 

increase in the basicity of the amine lone pair site in an amine azide fuel would lead to a 

concomitant increase in the fraction of a fuel sample that assumed a configuration in which the 

azide group shields the amine lone pair from proton attack. Such an effect would compromise 

the (presumed) benefit of substituent-mediated increases in the basicity of the site. In parallel 

with the effort summarized in this report, the author employed computational methods to 

quantify the differences in the basicity of amine azide lone pair sites. Based on gas-phase proton 

affinities, the basicities of MMAZ and CPAZ amine lone pair sites are nearly identical to each 

other, and they are less than that of the amine site in DMAZ. Thus, the finding that shielded 

configurations in MMAZ and CPAZ are, like DMAZ, ~1 kcal/mol (or more) lower in energy 

than otherwise similar conformers (i.e., B conformers vs. A conformers) does not support the 

suspicion that the strength of the interaction is related to the basicity of the amine site. Indeed, it 

is observed that other steric effects are more effective in reducing the energy of these molecules, 

two nonshielding configurations being found to be lower in energy than the shielded 

configurations. Clearly, amine basicity alone is not a good predictor of an amine azide’s 

propensity for assuming a shielded configuration. 

The possibility that substituent-mediated differences in the >N-CH2-CH2-N3 chain might be 

observed and indicate an ignition-enabling reaction mechanism was also considered. However, 

the energy differences of the eight lowest energy structures of MMAZ and CPAZ have the same 

>N-CH2-CH2-N3 chain orientation dependence and the geometric parameters of this chain in 

MMAZ and CPAZ analogs are essentially identical. Thus, it does not appear that the difference 

in MMAZ and CPAZ ignition delays is due to differences in their >NH-CH2-CH2-N3 chains. 

Rather, the results indicate that the cyclopropyl group is involved in the mechanism that enables 

ignition. 

Considering the ignition delays of MMAZ and DMAZ, the prediction that shielded 

configurations have a much smaller probability in a MMAZ sample than they do in a DMAZ 

sample is at odds with the hypothesis that shielding acts as a barrier to the ignition process. And 

though differences in the basicities of MMAZ and DMAZ lone pair sites are observed and may 

be a mitigating factor, coupled with the lack of differences observed between MMAZ and CPAZ, 

the potential of simple structural analyses for predicting the hypergolic ignition delays of 

2-azidothanamines appears to be negligible. The focus of future ARL computational studies will 

therefore shift to investigating the possible importance of reaction mechanisms.
19

5. Conclusions 

In an attempt to identify structural differences between DMAZ, MMAZ, and CPAZ that 

correlate with their ignition delays, equilibrium geometries and normal modes for MMAZ and 

CPAZ have been determined via B3LYP/6-311++G(d, p) calculations and compared to each 

other and to results obtained previously for DMAZ. It is observed that MMAZ and CPAZ 

conformer energy orderings have the same >NH-CH2-CH2-N3 chain orientation dependence, and 

that bond lengths, simple bond angles and dihedral angles in this chain are essentially the same 

for MMAZ and CPAZ analogs. Coupled with a prior finding that the site-specific basicities of 

the lone pair sites in these two molecules are nearly identical, the results imply that the 

difference in MMAZ and CPAZ hypergolicities is not associated with differences in their 

>N-CH2-CH2-N3 chains. Based on the results, it is also predicted that less than 15% of the 

molecules in 298 K gas-phase samples of either MMAZ or CPAZ will be in configurations 

where the amine lone pair site is shielded from proton attack by the azide group. This is in 

contrast to DMAZ, where approximately 45% of the molecules in a gas-phase sample at 298 K 

are in such a configuration. Taken together, the results indicate that structural characterizations 

(alone) will not predict a 2-azidothanamine’s ignition delay. 
20

6. References 

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of Chemical Physics 1993, 98, 5648–5652. 

Clark, T. J.; Chandrashakar, G. W.; Spitznagel; Schleyer, P. V. R. Efficient Diffuse FunctionAugmented Basis-Sets for Anion Calculations. 3. The 3-21+G Basis Set for 1st-Row 

Elements, Li-F. Journal of Computational Chemistry 1983, 4, 294–301. 

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Zakrzewski, V. G.; Montgomery, J. A.; Stratmann, R. E.; Burant, J. C.; Dapprich, S.; 

Millam, J. M.; Daniels, A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J.; 

Barone, V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.; Clifford, S.; 

Ochterski, J.; Petersson, G. A.; Ayala, P. Y.; Cui, Q.; Morokuma, K.; Salvador, P.; 

Dannenberg, J. J.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; 

Cioslowski, J.; Ortiz, J. V.; Baboul, A. G.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, 

P.; Komaromi, I.; Gomperts, R.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; 

Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; 

Wong, M. W.; Andres, J. L.; Gonzalez, C.; Head-Gordon, M.; Replogle; E. S.; Pople, J. A. 

Gaussian 98, Revision A.11., Gaussian, Inc., Pittsburgh, PA, 2001. 

Krishnan, R.; Binkley, J. S.; Seeger, R.; Pople, J. A. Self-Consistent Molecular-Orbital Methods. 

20. Basis Set for Correlated Wave-Functions. Journal of Chemical Physics 1980, 72, 

650–654. 

Lee, C.; Yang, W.; Parr, R. G. Development of the Colle-Salvetti Correlation-Energy Formula 

Into a Functional of the Electron-Density. Physical Review B 1988, 37, 785–789. 

McLean, A. D.; Chandler, G. S. Contracted Gaussian-Basis Sets for Molecular Calculations. 

1. 2nd Row Atoms, Z=11-18. Journal of Chemical Physics 1980, 72, 5639–5648. 

McQuaid, M. J. Computational Characterization of 2-Azidocycloalkanamines: Notional 

Variations on the Hypergol 2-Azido-N,N-Dimethylethanamine; ARL-TR-2806; U.S. Army 

Research Laboratory: Aberdeen Proving Ground, MD, September 2002. 

McQuaid, M. J. Computationally Based Measures of Amine Azide Basicity and Their 

Correlation With Hypergolic Ignition Delays; ARL-TR-3122; U.S. Army Research 

Laboratory: Aberdeen Proving Ground, MD, December 2003. 
21

McQuaid, M. J.; McNesby, K. L.; Rice, B. M.; Chabalowski, C. F. Density Functional Theory 

Characterization of the Structure and Gas-Phase, Mid-Infrared Absorption Spectrum of 

2-Azido–N,N-Dimethylethanamine (DMAZ). Journal of Molecular Structure (Theochem)

2002, 587, 199–218. 

Miehlich, B.; Savin, A.; Stoll, H.; Preuss, H. Results Obtained with the Correlation-Energy 

Density Functionals of Becke and Lee, Yang and Parr. Chemical Physics Letters 1989, 157, 

200–206. 

Nusca, M. J.; Michaels, R. S. Computational Model of Impurging-Stream/Swirl Injectors in a 

Hypergolic Fuel Engine. A1AA-2003-5062, 2003. 

Schmidt, E. W. Hydrazine and Its Derivatives. Preparation, Properties, and Applications. John 

Wiley & Sons, Inc.: New York, 2001. 

Stevenson, W. H. Synthesis and Characterization of Hypergolic Amino Azides. Proceedings of 

the 30th JANNAF Propellant Development and Characterization Subcommittee Meeting; 

CPIA Publication 708, 2002; Vol. II, pp 95–102. 

Thompson, D. M.; Wilson, B. F.; Stevenson, W. Hypergolic Azide Liquid Fuels. Proceedings 

of the 1998 JANNAF Propulsion Meeting; CPIA Publication 675, 1998; Vol. III, 

pp 515–523; private communications with D. M. Thompson and W. Stevenson. 
22

Appendix. Geometric Parameters and Normal Mode Frequencies for 

2-Azido-N-Methylethanamine (MMAZ) and 2-Azido-NCyclopropylethanamine (CPAZ) 

This appendix provides complete descriptions of the geometric parameters and normal mode 

frequencies of equilibrium 2-azido-N-methylethanamine (MMAZ) and 2-azido-Ncyclopropylethanamine (CPAZ) structures. Atom labels in the tables of geometric parameters 

refer to those of the figures in the main body of this report. 
23

Table A-1. Geometric parameters for MMAZ group 1 conformers. 

MMAZ Conformer 

Parameter A1 B1 C1 D1 E1 F1 G1 H1 I1 J1 L1 

Bond Length (Å) 

H1-C1 1.093 1.093 1.094 1.094 1.094 1.094 1.094 1.094 1.094 1.094 1.094 

H2-C1 1.092 1.092 1.092 1.092 1.092 1.092 1.092 1.092 1.092 1.092 1.092 

H3-C1 1.104 1.103 1.103 1.103 1.103 1.103 1.103 1.101 1.102 1.102 1.101 

C1-N1 1.458 1.460 1.458 1.459 1.460 1.461 1.461 1.460 1.459 1.459 1.460 

N1-C2 1.453 1.456 1.454 1.455 1.458 1.457 1.458 1.454 1.454 1.454 1.454 

H4-N1 1.015 1.015 1.015 1.015 1.015 1.015 1.015 1.013 1.013 1.014 1.014 

C2-C3 1.528 1.528 1.526 1.519 1.524 1.531 1.531 1.544 1.536 1.534 1.541 

H5-C2 1.107 1.106 1.107 1.105 1.103 1.105 1.103 1.095 1.095 1.096 1.097 

H6-C2 1.097 1.094 1.097 1.096 1.094 1.094 1.096 1.095 1.094 1.094 1.096 

C3-N2 1.479 1.476 1.486 1.486 1.481 1.479 1.480 1.480 1.483 1.484 1.484 

H7-C3 1.092 1.098 1.095 1.096 1.095 1.089 1.095 1.097 1.096 1.096 1.090 

H8-C3 1.097 1.091 1.090 1.095 1.098 1.097 1.091 1.089 1.098 1.097 1.097 

N2-N3 1.227 1.230 1.229 1.228 1.228 1.229 1.229 1.229 1.228 1.228 1.229 

N3-N4 1.136 1.134 1.136 1.135 1.136 1.136 1.136 1.136 1.136 1.136 1.136 

Simple Angle (degrees) 

H1-C1-N1 109.4 109.4 109.6 109.6 109.4 109.4 109.4 109.0 109.0 109.3 109.2 

H2-C1-N1 109.5 109.4 109.5 109.5 109.4 109.4 109.4 109.1 109.1 109.1 109.1 

H3-C1-N1 114.0 114.0 113.9 113.9 113.9 113.9 113.9 115.3 115.4 115.2 115.1 

C1-N1-C2 113.8 114.2 113.8 113.5 113.7 113.8 113.7 116.4 116.6 115.9 115.7 

N1-C2-C3 112.5 111.3 111.1 111.1 110.0 110.1 110.0 115.7 115.7 116.7 116.9 

C2-C3-N2 115.6 113.2 112.2 108.4 108.3 112.4 112.4 112.2 107.9 108.1 112.3 

H4-N1-C2 110.4 110.0 109.4 108.9 109.9 110.0 109.8 111.5 111.5 109.9 110.1 

H5-C2-C3 107.0 108.3 109.3 109.0 109.2 109.7 109.2 108.6 108.7 107.8 107.7 

H6-C2-C3 109.7 108.6 108.0 108.0 108.8 108.6 109.2 108.9 108.3 108.3 108.8 

C3-N2-N3 116.9 117.2 116.2 116.2 116.2 116.5 116.4 116.5 116.1 116.2 116.4 

H7-C3-N2 104.6 110.5 110.3 109.6 110.8 106.0 111.1 110.4 109.8 109.8 105.2 

H8-C3-N2 109.6 105.4 105.4 109.9 109.7 110.2 105.1 105.1 109.9 110.0 110.4 

N2-N3-N4 173.1 171.8 173.3 173.9 173.6 173.0 173.1 173.0 173.8 173.9 173.3 

Dihedral Angle (degrees) 

H1-C1-N1-C2 –64.5 –64.8 –65.0 –65.3 –65.3 –65.1 –65.3 –58.2 –57.9 –60.5 –60.0 

H2-C1-N1-C2 177.8 177.5 177.2 176.9 177.0 177.2 176.9 –175.3 –174.9 –177.7 –177.2

H3-C1-N1-C2 56.2 56.0 55.7 55.5 55.5 55.7 55.4 63.2 63.5 61.1 61.6

C1-N1-C2-C3 –178.7 170.0 –177.4 –179.4 172.8 172.9 173.7 –66.9 –66.1 –65.1 –65.4 

N1-C2-C3-N2 –56.4 –68.1 63.7 64.8 178.3 –178.0 176.4 177.4 –178.9 –60.8 –59.9 

H4-N1-C2-C3 –53.9 –66.0 –53.3 –56.3 –63.9 –63.5 –63.1 62.4 63.5 61.5 60.9

C2-C3-N2-N3 –47.0 80.3 84.3 –172.1 176.6 –78.4 79.1 77.1 –178.1 176.1 –83.0 

H5-C2-C3-N2 178.4 166.5 –61.9 –60.4 53.1 56.8 51.2 55.3 58.8 176.8 177.9 

H6-C2-C3-N2 63.8 50.8 –177.4 –176.3 –63.1 –59.5 –65.3 –60.6 –56.7 61.4 62.8

C3-N2-N3-N4 179.3 169.4 173.9 –178.8 180.0 –174.4 175.8 173.8 –179.7 179.4 –174.0

H7-C3-N2-N3 –168.8 –44.1 –39.1 67.8 56.2 161.9 –44.5 –46.3 –56.9 54.6 156.1 

H8-C3-N2-N3 76.6 –160.0 –156.4 –52.0 –63.1 45.4 –161.0 –162.4 62.0 –64.2 40.0
24

Table A-2. Geometric parameters for MMAZ group 2 conformers. 

MMAZ Conformer 

Parameter A2 B2 C2 D2 E2 F2 G2 H2 I2 J2 K2 L2 X2 

Bond Length (Å) 

H1-C1 1.093 1.093 1.091 1.089 1.093 1.093 1.093 1.094 1.094 1.093 1.093 1.094 1.092

H2-C1 1.092 1.092 1.092 1.092 1.092 1.092 1.092 1.092 1.092 1.093 1.093 1.093 1.092

H3-C1 1.104 1.103 1.103 1.103 1.103 1.103 1.103 1.101 1.102 1.097 1.104 1.104 1.104

C1-N1 1.459 1.459 1.463 1.464 1.461 1.461 1.461 1.459 1.459 1.462 1.460 1.462 1.462

N1-C2 1.455 1.457 1.458 1.461 1.459 1.459 1.460 1.454 1.454 1.453 1.452 1.452 1.453

H4-N1 1.012 1.011 1.013 1.012 1.012 1.012 1.012 1.013 1.013 1.014 1.013 1.014 1.011

C2-C3 1.532 1.532 1.534 1.525 1.528 1.536 1.536 1.543 1.536 1.534 1.541 1.543 1.532

H5-C2 1.107 1.105 1.106 1.103 1.102 1.104 1.102 1.094 1.095 1.096 1.097 1.097 1.099

H6-C2 1.095 1.093 1.095 1.094 1.092 1.093 1.094 1.096 1.094 1.095 1.095 1.096 1.097

C3-N2 1.478 1.475 1.484 1.485 1.482 1.481 1.481 1.481 1.483 1.484 1.483 1.482 1.479

H7-C3 1.090 1.096 1.097 1.097 1.095 1.089 1.095 1.095 1.096 1.098 1.096 1.091 1.093

H8-C3 1.097 1.091 1.089 1.095 1.096 1.095 1.089 1.091 1.098 1.098 1.094 1.098 1.095

N2-N3 1.227 1.230 1.228 1.227 1.227 1.229 1.229 1.229 1.228 1.228 1.225 1.228 1.229

N3-N4 1.136 1.135 1.136 1.136 1.136 1.136 1.136 1.136 1.136 1.136 1.137 1.136 1.135

Simple Angle (degrees) 

H1-C1-N1 110.2 110.3 110.0 109.9 110.3 110.3 110.5 110.1 109.0 108.9 109.0 109.0 110.0

H2-C1-N1 109.2 109.2 109.2 109.2 109.2 109.2 109.2 109.2 109.1 109.3 109.3 109.3 109.2

H3-C1-N1 113.7 113.6 113.4 113.3 113.6 113.6 113.6 115.4 115.4 115.1 115.7 114.9 113.6

C1N1-C2 115.3 115.2 115.7 115.5 115.0 115.0 114.9 116.6 116.6 117.7 118.5 117.4 115.6

N1-C2-C3 113.3 112.0 113.6 113.5 110.8 110.9 110.7 115.7 115.7 118.5 118.7 118.4 112.3

H4-N1-C2 109.5 110.6 109.2 109.4 109.9 110.1 110.1 111.4 107.9 111.3 111.8 111.0 110.7

C2-C3-N2 115.4 112.7 114.4 110.3 108.0 111.9 112.2 112.0 111.5 110.6 112.9 115.0 112.4

H5-C2-C3 106.4 108.0 109.0 108.7 108.8 109.3 108.8 108.2 108.7 106.5 106.3 106.4 109.0

H6-C2-C3 109.1 108.0 106.5 106.5 108.3 108.1 108.7 109.1 108.3 108.6 108.4 109.2 107.1

C3-N2-N3 117.2 117.1 116.3 116.0 116.2 116.6 116.5 116.5 116.1 116.0 117.3 116.3 116.8

H7-C3-N2 104.8 110.5 105.5 108.9 110.6 106.1 111.0 110.2 109.8 109.9 110.6 105.0 105.9

H8-C3-N2 109.6 105.5 105.4 110.1 109.7 110.2 105.1 105.4 109.9 109.3 106.2 109.7 110.4

N2-N3-N4 173.0 173.7 173.2 173.8 173.7 173.1 173.1 173.1 173.8 173.8 173.6 173.3 173.5

Dihedral Angle (degrees)

H1-C1-N1-C2 69.9 65.5 68.2 65.5 66.8 66.6 66.5 58.1 –57.9 56.1 51.4 56.9 62.5

H2-C1-N1-C2 –172.6 –177.0 –173.6 –176.1 –175.6 –175.8 –175.9 175.1 –174.9 172.9 168.4 173.6 –179.5

H3-C1-N1-C2 –51.5 –55.6 –57.8 –55.1 –54.3 –54.5 –54.6 –63.4 63.5 –64.8 –70.1 –64.3 –58.3

C1-N1-C2-C3 –72.7 –84.7 –81.7 –88.9 –84.8 –85.0 –84.6 66.5 –66.1 72.8 74.1 69.8 –106.1

N1-C2-C3-N2 –53.9 –66.9 73.1 72.3 178.5 –178.3 176.0 176.7 –178.9 –71.8 –73.6 –69.4 62.2

H4-N1-C2-C3 162.4 149.2 154.0 147.1 150.4 150.0 150.6 –63.0 63.5 –57.3 –58.2 –59.5 127.9

C2-C3-N2-N3 –44.8 81.2 77.2 –170.9 178.2 –80.9 78.7 80.5 –178.1 177.4 111.3 –72.5 –94.0

H5-C2-C3-N2 –178.3 168.6 –53.7 –53.9 53.9 57.3 51.5 54.5 58.8 106.7 164.7 169.1 –61.8

H6-C2-C3-N2 66.2 52.7 –168.5 –169.0 –62.2 –59.0 –65.0 –61.3 –56.7 52.2 50.4 54.9 –177.1

C3-N2-N3-N4 –179.9 168.0 175.8 180.0 –179.7 –174.2 175.3 174.8 –179.7 –179.2 –176.7 –177.2 –172.0

H7-C3-N2-N3 –167.3 –43.4 –46.1 69.2 58.2 159.9 –44.5 –43.9 –56.9 55.6 –13.1 166.4 146.3

H8-C3-N2-N3 78.2 –159.5 –167.8 –50.2 –61.1 43.2 –161.1 –160.1 62.0 –62.6 –130.0 51.0 28.9
25

Table A-3. Normal mode frequencies (cm-1) for MMAZ group 1 conformers. 

 Conformer 

Mode A1 B1 C1 D1 E1 F1 G1 H1 I1 J1 L1 

1 31 58 35 39 34 45 41 46 34 35 35 

2 89 94 108 89 102 85 83 60 90 81 58 

3 147 111 118 142 112 109 106 124 114 133 134 

4 177 221 205 192 123 187 191 191 139 196 188 

5 245 258 242 238 230 231 237 231 218 238 245 

6 273 283 293 283 257 266 255 293 319 261 300 

7 346 344 354 327 368 394 394 349 322 400 410 

8 522 517 517 520 430 421 423 469 462 520 515 

9 561 558 554 556 549 556 557 556 549 553 554 

10 686 652 658 639 662 677 677 677 656 626 658 

11 731 751 768 781 770 767 768 684 684 723 713 

12 842 832 825 839 813 812 817 785 786 818 817 

13 865 900 879 882 936 922 919 922 933 869 850 

14 990 990 989 1005 995 984 984 956 964 988 960 

15 1023 1024 1022 1033 1052 1031 1033 1000 1031 1000 999 

16 1061 1047 1088 1081 1082 1082 1079 1048 1049 1048 1053 

17 1137 1133 1146 1142 1139 1136 1136 1139 1140 1142 1145 

18 1168 1165 1155 1161 1161 1171 1169 1169 1158 1156 1157 

19 1188 1188 1191 1195 1186 1190 1194 1192 1188 1197 1189 

20 1272 1281 1245 1245 1256 1260 1258 1272 1269 1246 1255 

21 1289 1283 1300 1305 1313 1307 1306 1308 1327 1318 1310 

22 1333 1344 1336 1338 1332 1328 1323 1342 1337 1337 1336 

23 1388 1386 1376 1376 1345 1357 1362 1356 1341 1372 1374 

24 1405 1393 1395 1402 1416 1407 1409 1402 1405 1395 1394 

25 1459 1458 1459 1458 1459 1459 1459 1456 1456 1454 1455 

26 1485 1481 1487 1481 1487 1487 1488 1483 1484 1474 1475 

27 1491 1491 1487 1487 1494 1493 1494 1492 1492 1482 1485 

28 1500 1494 1495 1495 1499 1501 1501 1494 1495 1496 1497 

29 1513 1507 1509 1506 1516 1516 1516 1503 1501 1502 1503 

30 1520 1519 1519 1518 1522 1520 1521 1524 1524 1525 1526 

31 2234 2239 2229 2239 2238 2228 2230 2226 2235 2237 2229 

32 2900 2909 2901 2924 2940 2918 2940 2953 2948 2945 2952 

33 2933 2940 2935 2936 2943 2942 2943 3005 2994 3001 3009 

34 3012 3002 3022 3010 2995 3006 3035 3024 3033 3024 3022 

35 3022 3054 3035 3039 3045 3054 3038 3049 3038 3042 3046 

36 3051 3055 3047 3047 3053 3056 3053 3065 3048 3045 3050 

37 3091 3100 3097 3059 3063 3098 3098 3093 3078 3071 3093 

38 3099 3103 3118 3096 3098 3125 3099 3118 3092 3092 3112 

39 3522 3512 3524 3522 3514 3515 3515 3540 3541 3538 3536 
26

Table A-4. Normal mode frequencies (cm-1) for MMAZ group 2 conformers. 

 Conformer 

Mode A2 B2 C2 X2 D2 E2 F2 G2 H2 I2 J2 K2 L2 

1 33 60 40 38 35 35 51 40 50 34 36 27 38 

2 64 73 74 72 80 90 56 58 54 90 62 51 69 

3 162 126 135 96 130 108 114 109 126 114 120 128 141 

4 176 201 213 189 185 134 192 189 197 139 186 210 209 

5 250 267 229 258 208 213 242 233 239 218 211 244 225 

6 296 283 342 285 313 320 307 306 294 319 307 306 337 

7 398 405 370 388 378 354 357 363 339 322 354 354 351 

8 509 496 487 489 485 445 454 455 467 462 496 495 502 

9 561 556 555 548 553 550 555 557 553 549 552 542 556 

10 685 651 656 640 628 650 675 677 675 656 629 642 655 

11 721 720 729 694 732 737 727 727 681 684 676 653 686 

12 827 828 813 810 820 796 799 796 789 786 819 789 811 

13 855 872 872 896 880 930 922 924 917 933 867 887 862 

14 970 982 969 946 967 959 937 939 955 964 978 957 962 

15 997 999 1000 1007 1024 1050 1023 1023 1001 1031 1014 995 989 

16 1064 1048 1080 1073 1073 1074 1081 1077 1048 1049 1037 1040 1044 

17 1133 1138 1147 1145 1149 1144 1144 1143 1139 1140 1146 1144 1149 

18 1168 1159 1162 1161 1164 1157 1160 1161 1166 1158 1164 1161 1156 

19 1195 1191 1180 1180 1183 1181 1189 1188 1197 1188 1182 1191 1189 

20 1270 1267 1257 1262 1253 1259 1263 1263 1271 1269 1267 1267 1271 

21 1288 1299 1319 1312 1322 1328 1319 1310 1315 1327 1321 1316 1311 

22 1336 1345 1334 1355 1342 1334 1331 1335 1337 1337 1338 1366 1338 

23 1394 1380 1382 1379 1384 1343 1358 1360 1360 1341 1382 1376 1382 

24 1405 1398 1398 1394 1403 1413 1406 1409 1399 1405 1391 1392 1389 

25 1458 1458 1458 1456 1456 1459 1459 1459 1456 1456 1456 1456 1456 

26 1484 1481 1481 1479 1477 1485 1485 1485 1483 1484 1471 1471 1472 

27 1492 1486 1486 1483 1479 1492 1491 1491 1492 1492 1479 1480 1484 

28 1499 1493 1487 1487 1486 1496 1496 1496 1495 1495 1490 1494 1492 

29 1506 1498 1502 1496 1501 1507 1507 1508 1504 1501 1501 1502 1503 

30 1520 1520 1526 1523 1525 1520 1519 1519 1524 1524 1524 1527 1526 

31 2233 2236 2226 2236 2235 2237 2228 2228 2227 2235 2234 2234 2227 

32 2902 2918 2913 2944 2941 2942 2929 2943 2952 2948 2983 2976 2986 

33 2931 2939 2937 2986 2945 2950 2942 2949 3021 2994 2992 3008 2996 

34 3010 3019 3013 3026 2998 3012 3029 3039 3029 3033 3015 3015 3012 

35 3051 3056 3053 3045 3054 3051 3058 3056 3048 3038 3027 3053 3045 

36 3060 3072 3071 3066 3060 3058 3074 3059 3067 3048 3055 3060 3052 

37 3102 3100 3113 3088 3071 3078 3100 3100 3093 3078 3063 3071 3087 

38 3110 3101 3121 3106 3119 3099 3125 3119 3100 3092 3088 3091 3098 

39 3555 3564 3546 3568 3550 3561 3558 3558 3541 3541 3537 3545 3536 
27

Table A-5. Geometric parameters for CPAZ group 11 conformers. 

CPAZ Conformer 

Parameter A11 B11 C11 D11 E11 F11 G11 H11 I11 J11 L11 

Bond Length (Å) 

H5-C3 1.093 1.093 1.093 1.093 1.093 1.093 1.093 1.091 1.092 1.092 1.091 

C3-N1 1.439 1.441 1.439 1.440 1.441 1.441 1.441 1.440 1.439 1.439 1.440 

N1-C4 1.457 1.459 1.458 1.459 1.461 1.460 1.461 1.457 1.457 1.457 1.457 

H6-N1 1.016 1.016 1.016 1.016 1.016 1.016 1.016 1.014 1.014 1.015 1.015 

C4-C5 1.528 1.528 1.526 1.519 1.524 1.531 1.531 1.542 1.534 1.532 1.539 

H7-C4 1.105 1.105 1.105 1.103 1.102 1.104 1.102 1.093 1.094 1.095 1.096 

H8-C4 1.096 1.093 1.096 1.095 1.093 1.093 1.094 1.095 1.094 1.094 1.096 

C5-N2 1.480 1.476 1.487 1.486 1.481 1.480 1.480 1.481 1.483 1.484 1.484 

H9-C5 1.091 1.098 1.095 1.096 1.095 1.089 1.095 1.097 1.098 1.096 1.090 

H10-C5 1.097 1.091 1.090 1.095 1.098 1.097 1.091 1.089 1.096 1.097 1.097 

N2-N3 1.227 1.230 1.229 1.228 1.228 1.229 1.229 1.229 1.228 1.228 1.229 

N3-N4 1.136 1.135 1.136 1.135 1.136 1.136 1.136 1.136 1.136 1.136 1.136 

Simple Angle (degrees) 

H5-C3-N1 116.9 116.9 116.9 116.9 116.9 116.9 116.9 118.1 118.2 118.0 117.9 

C3-N1-C4 114.4 114.8 114.3 114.1 114.2 114.4 114.3 116.9 117.1 116.2 116.1 

N1-C4-C5 112.3 111.2 111.0 111.0 109.9 110.0 109.8 115.2 115.3 116.4 116.6 

H6-N1-C4 110.8 110.5 109.9 109.4 110.4 110.5 110.3 111.9 111.9 110.3 110.6 

C4-C5-N2 115.5 113.2 112.3 108.5 108.2 112.3 112.4 112.3 108.0 108.3 112.4 

H7-C4-C5 107.0 108.2 109.3 108.9 109.1 109.6 109.1 108.7 108.8 108.0 107.8 

H8-C4-C5 109.9 108.9 108.2 108.2 109.1 108.9 109.5 109.0 108.5 108.4 108.9 

C5-N2-N3 116.9 117.2 116.2 116.2 116.2 116.5 116.4 116.5 116.1 116.2 116.3 

H9-C5-N2 104.6 110.4 110.2 109.6 110.7 106.0 111.0 110.3 109.9 109.9 105.3 

H10-C5-N2 109.5 105.4 105.3 109.9 109.7 110.2 105.1 105.1 109.9 109.9 110.4 

N2-N3-N4 173.1 171.9 173.3 173.9 173.6 173.0 173.0 173.0 173.8 173.9 173.3 

Dihedral Angle (degrees) 

H5-C3-N1-C4 56.8 57.2 56.6 56.4 56.3 56.7 56.4 62.7 62.9 61.7 61.9

C3-N1-C4-C5 179.7 168.8 –178.2 179.5 171.5 171.4 172.0 –67.6 –66.9 –65.7 –66.2

N1-C4-C5-N2 –56.6 –68.0 63.5 64.6 177.9 –178.3 176.1 177.9 –178.5 –60.8 –60.0

H6-N1-C4-C5 –53.8 –66.0 –53.2 –56.5 –64.3 –64.0 –63.7 62.8 63.8 61.8 61.0

C4-C5-N2-N3 –47.4 81.3 83.9 –172.0 176.7 –78.3 78.7 77.1 –177.5 175.3 –82.6

H7-C4-C5-N2 178.4 166.9 –61.8 –60.4 52.9 56.8 51.1 55.9 59.4 177.0 178.1

H8-C4-C5-N3 63.5 50.9 –177.6 –176.5 –63.6 –59.8 –65.7 –60.4 –56.6 61.1 62.6

C5-N2-N3-N4 178.9 168.8 174.0 –179.2 –179.8 –174.3 175.5 174.1 –179.7 179.5 –174.2

H9-C5-N2-N3 –169.2 –43.1 –39.6 67.9 56.3 162.0 –45.0 –46.4 62.4 53.9 156.7

H10-C5-N2-N3 76.2 –159.1 –156.8 –51.9 –62.9 45.5 –161.4 –162.6 –56.5 –65.0 40.5
28

Table A-6. Geometric parameters for CPAZ group 21 conformers. 

CPAZ Conformer 

Parameter A21 B21 C21 D21 E21 F21 G21 H21 I21 J21 L21 

Bond Length (Å) 

H5- C3 1.094 1.093 1.093 1.092 1.093 1.093 1.093 1.091 1.092 1.088 1.089 

C3-N1 1.440 1.441 1.444 1.444 1.442 1.442 1.442 1.440 1.439 1.442 1.442 

N1-C4 1.458 1.460 1.463 1.464 1.462 1.462 1.463 1.457 1.457 1.457 1.455 

H6-N1 1.014 1.013 1.013 1.014 1.013 1.013 1.013 1.014 1.014 1.014 1.015 

C4-C5 1.532 1.531 1.533 1.526 1.527 1.535 1.535 1.542 1.534 1.532 1.541 

H7-C4 1.105 1.104 1.104 1.102 1.101 1.103 1.101 1.094 1.094 1.097 1.097 

H8-C4 1.095 1.093 1.095 1.094 1.093 1.093 1.094 1.095 1.094 1.093 1.095 

C5-N2 1.479 1.477 1.481 1.483 1.483 1.481 1.481 1.481 1.483 1.483 1.482 

H9-C5 1.089 1.095 1.098 1.097 1.095 1.089 1.095 1.095 1.096 1.098 1.091 

H10-C5 1.097 1.091 1.089 1.095 1.095 1.094 1.088 1.091 1.098 1.098 1.098 

N2-N3 1.227 1.229 1.227 1.226 1.227 1.229 1.229 1.229 1.228 1.228 1.228 

N3-N4 1.136 1.135 1.137 1.137 1.136 1.136 1.136 1.136 1.136 1.136 1.136 

Simple Angle (degrees) 

H5-C3-N1 116.5 116.0 116.1 116.2 116.3 116.3 116.3 118.1 118.1 117.8 117.7 

C3-N1-C4 115.7 115.5 116.4 116.4 115.4 115.5 115.3 117.0 117.1 117.6 117.6 

N1-C4-C5 113.5 112.6 114.4 114.3 111.4 111.5 111.3 115.3 115.3 117.6 117.9 

H6-N1-C4 110.1 110.6 109.5 109.1 109.9 110.0 110.0 111.8 111.9 111.7 111.5 

C4-C5-N2 115.2 112.6 115.2 110.4 107.8 111.6 112.0 112.0 108.0 110.6 114.8 

H7-C4-C5 106.5 107.9 109.2 108.2 108.7 109.1 108.6 108.4 108.5 106.4 106.5 

H8-C4-C5 109.3 108.1 106.2 106.9 108.3 108.1 108.8 109.3 108.8 109.2 109.5 

C5-N2-N3 117.0 117.4 116.5 116.2 116.2 116.6 116.5 116.5 116.1 116.0 116.3 

H9-C5-N2 104.8 110.7 109.2 108.5 110.5 106.0 110.9 110.2 109.9 109.7 105.0 

H10-C5-N2 109.6 105.3 105.3 110.7 109.9 110.4 105.3 105.3 109.9 109.6 109.8 

N2-N3-N4 173.1 171.9 173.1 173.7 173.7 173.1 173.1 173.1 173.8 173.8 173.3 

Dihedral Angle (degrees) 

H5-C3-N1-C4 –51.5 –49.2 –48.9 –45.1 –49.1 –49.6 –49.4 –62.9 –62.9 –60.4 –62.3 

C3-N1-C4-C5 –72.5 –87.4 –88.3 –80.9 –82.2 –82.8 –82.1 67.1 66.8 79.7 72.7 

N1-C4-C5-N2 –55.0 –68.1 72.4 80.3 –178.6 –176.1 178.4 176.5 178.5 –67.7 –67.6 

H6-N1-C4-C5 161.3 146.6 147.0 154.8 152.9 151.9 152.8 –63.5 –63.8 –51.0 –57.5 

C4-C5-N2-N3 –48.1 83.1 68.1 –163.9 –178.5 –82.2 78.0 80.3 177.5 177.8 –73.4 

H7-C4-C5-N2 180.0 167.5 –54.6 –46.3 56.7 59.3 53.7 54.6 56.6 170.7 171.1 

H8-C4-C5-N3 65.2 51.7 –169.1 –161.5 –59.4 –57.0 –62.8 –61.6 –59.3 55.7 56.4 

C5-N2-N3-N4 179.9 168.7 178.0 178.5 –179.6 –174.4 175.2 174.9 179.7 –179.8 –176.7 

H9-C5-N2-N3 –170.1 –41.4 –55.0 76.8 61.8 158.7 –45.1 –43.9 56.5 56.3 165.6 

H10-C5-N2-N3 74.8 –157.9 –171.3 –42.4 –57.8 41.7 –162.0 –160.2 –62.5 –61.9 50.2 
29

Table A-7. Geometric parameters for CPAZ group 12 conformers. 

CPAZ Conformer 

Parameter A12 B12 C12 D12 E12 F12 G12 

Bond Length (Å) 

H5-C3 1.086 1.086 1.087 1.087 1.086 1.086 1.086 

C3-N1 1.440 1.441 1.440 1.441 1.442 1.442 1.442 

N1-C4 1.456 1.459 1.458 1.459 1.460 1.460 1.461 

H6-N1 1.014 1.015 1.015 1.015 1.015 1.015 1.015 

C4-C5 1.528 1.528 1.526 1.519 1.524 1.531 1.531 

H7-C4 1.104 1.104 1.104 1.102 1.101 1.103 1.101 

H8-C4 1.096 1.094 1.096 1.095 1.094 1.094 1.095 

C5-N2 1.479 1.476 1.487 1.486 1.481 1.480 1.480 

H9-C5 1.092 1.098 1.095 1.096 1.095 1.089 1.095 

H10-C5 1.097 1.091 1.090 1.095 1.098 1.098 1.091 

N2-N3 1.227 1.230 1.229 1.228 1.228 1.229 1.229 

N3-N4 1.136 1.134 1.136 1.135 1.136 1.136 1.136 

Simple Angle (degrees) 

H5-C3-N1 112.4 112.3 112.5 112.5 112.3 112.3 112.3 

C3-N1-C4 114.6 114.9 114.6 114.4 114.4 114.5 114.5 

N1-C4-C5 112.3 111.2 110.9 110.8 109.8 109.9 109.8 

H6-N1-C4 111.3 110.9 110.2 109.7 110.8 110.9 110.7 

C4-C5-N2 115.6 113.2 112.2 108.4 108.2 112.3 112.4 

H7-C4-C5 107.2 108.5 109.6 109.2 109.4 109.9 109.3 

H8-C4-C5 109.7 108.7 108.0 108.0 108.9 108.7 109.3 

C5-N2-N3 116.9 117.2 116.2 116.2 116.2 116.5 116.4 

H9-C5-N2 104.6 110.5 110.2 109.6 110.8 106.0 111.0 

H10-C5-N2 109.6 105.4 105.3 109.9 109.7 110.2 105.1 

N2-N3-N4 173.1 171.9 173.3 173.9 173.6 173.0 173.1 

Dihedral Angle (degrees) 

H5-C3-N1-C4 –72.4 –72.0 –72.1 –72.2 –72.3 –72.2 –72.6 

C3-N1-C4-C5 179.5 167.2 –178.9 178.8 170.0 170.3 170.8 

N1-C4-C5-N2 –56.7 –68.1 63.6 64.5 178.3 –178.1 176.2 

H6-N1-C4-C5 –53.1 –66.4 –52.5 –55.9 –64.3 –63.9 –63.5 

C4-C5-N2-N3 –48.4 81.1 83.9 –172.7 176.9 –78.3 78.7 

H7-C4-C5-N2 178.1 166.6 –61.9 –60.6 53.1 56.8 51.0 

H8-C4-C5-N3 63.3 50.7 –177.7 –176.7 –63.3 –59.7 –65.7 

C5-N2-N3-N4 179.3 168.8 173.9 –179.1 179.9 –174.5 175.6 

H9-C5-N2-N3 –170.2 –43.3 –39.5 67.3 56.4 161.9 –45.1 

H10-C5-N2-N3 75.2 –159.2 –156.8 –52.5 –62.8 45.4 –161.5 
30

Table A-8. Geometric parameters for CPAZ group 22 conformers. 

CPAZ Conformer 

Parameter A22 B22 C22 D22 E22 F22 G22 

Bond Length (Å) 

H5-C3 1.086 1.086 1.084 1.083 1.086 1.086 1.086 

C3-N1 1.440 1.440 1.444 1.444 1.442 1.442 1.442 

N1-C4 1.456 1.458 1.461 1.463 1.461 1.460 1.461 

H6-N1 1.012 1.011 1.012 1.012 1.011 1.011 1.011 

C4-C5 1.532 1.532 1.533 1.525 1.527 1.535 1.535 

H7-C4 1.104 1.103 1.103 1.100 1.100 1.102 1.100 

H8-C4 1.095 1.093 1.095 1.094 1.093 1.093 1.094 

C5-N2 1.479 1.476 1.484 1.484 1.482 1.480 1.481 

H9-C5 1.090 1.096 1.097 1.098 1.095 1.089 1.095 

H10-C5 1.097 1.091 1.089 1.095 1.096 1.095 1.090 

N2-N3 1.227 1.230 1.228 1.227 1.227 1.229 1.229 

N3-N4 1.136 1.135 1.136 1.136 1.136 1.136 1.136 

Simple Angle (degrees) 

H5-C3-N1 113.2 113.6 113.0 112.9 113.4 113.4 113.4 

C3-N1-C4 116.4 116.6 116.6 116.3 116.3 116.3 116.2 

N1-C4-C5 113.1 112.1 113.3 113.2 110.8 110.9 110.7 

H6-N1-C4 111.3 112.0 110.5 110.6 111.1 111.3 111.3 

C4-C5-N2 115.4 112.8 114.2 110.0 108.0 111.9 112.2 

H7-C4-C5 106.4 107.9 109.2 109.0 108.8 109.2 108.8 

H8-C4-C5 109.4 108.2 106.6 106.6 108.3 108.2 108.9 

C5-N2-N3 117.1 117.1 116.3 116.1 116.2 116.6 116.5 

H9-C5-N2 104.8 110.5 109.5 109.1 110.6 106.1 111.0 

H10-C5-N2 109.6 105.5 105.3 110.0 109.8 110.2 105.1 

N2-N3-N4 173.0 171.9 173.2 173.8 173.7 173.0 173.1 

Dihedral Angle (degrees) 

H5-C3-N1-C4 79.4 78.2 75.8 72.6 78.6 78.6 78.3 

C3-N1-C4-C5 –68.6 –81.5 –81.7 –89.5 –81.1 –81.1 –80.9 

N1-C4-C5-N2 –54.2 –66.2 70.4 70.4 –179.9 –177.4 177.3 

H6-N1-C4-C5 161.8 148.0 151.0 143.6 150.4 150.2 150.6 

C4-C5-N2-N3 –46.7 82.0 75.5 –171.2 –179.7 –80.8 77.9 

H7-C4-C5-N2 –179.1 169.5 –56.0 –55.3 55.6 58.3 52.8 

H8-C4-C5-N3 65.7 53.3 –171.3 –170.9 –60.9 –58.4 –64.1 

C5-N2-N3-N4 –180.0 167.9 175.5 –180.0 –179.7 –174.2 175.3 

H9-C5-N2-N3 –168.8 –42.5 –47.8 68.9 60.3 159.8 –45.4 

H10-C5-N2-N3 76.5 –158.7 –164.5 –50.6 –59.1 43.0 –162.0 
31

Table A-9. Geometric parameters for CPAZ group 13 conformers. 

CPAZ Conformer 

Parameter A13 B13 C13 D13 E13 F13 G13 

Bond Length (Å) 

H5-C3 1.085 1.085 1.085 1.085 1.085 1.085 1.085 

C3-N1 1.447 1.450 1.448 1.448 1.450 1.450 1.450 

N1-C4 1.453 1.456 1.454 1.456 1.458 1.457 1.458 

H6-N1 1.015 1.016 1.016 1.016 1.016 1.016 1.016 

C4-C5 1.529 1.530 1.527 1.520 1.525 1.533 1.533 

H7-C4 1.105 1.104 1.105 1.103 1.101 1.103 1.101 

H8-C4 1.095 1.092 1.094 1.093 1.092 1.092 1.093 

C5-N2 1.479 1.475 1.486 1.486 1.481 1.479 1.480 

H9-C5 1.091 1.098 1.095 1.096 1.095 1.089 1.094 

H10-C5 1.097 1.091 1.090 1.095 1.098 1.097 1.091 

N2-N3 1.228 1.231 1.229 1.228 1.228 1.229 1.229 

N3-N4 1.136 1.134 1.135 1.135 1.136 1.136 1.136 

Simple Angle (degrees) 

H5-C3-N1 110.5 109.9 110.4 110.2 109.9 109.9 109.9 

C3-N1-C4 118.9 119.0 118.7 118.5 118.5 118.6 118.6 

N1-C4-C5 111.5 110.4 110.1 110.1 109.1 109.2 109.0 

H6-N1-C4 110.3 109.5 109.2 108.7 109.4 109.5 109.3 

C4-C5-N2 115.5 113.2 112.4 108.5 108.1 112.2 112.3 

H7-C4-C5 106.3 108.0 108.7 108.4 108.8 109.3 108.7 

H8-C4-C5 109.3 108.0 107.5 107.4 108.3 108.1 108.7 

C5-N2-N3 116.8 117.2 116.2 116.2 116.1 116.5 116.4 

H9-C5-N2 104.6 110.5 110.2 109.6 110.8 106.1 111.1 

H10-C5-N2 109.7 105.4 105.4 109.9 109.7 110.2 105.2 

N2-N3-N4 173.0 171.7 173.3 173.9 173.6 173.0 173.0 

Dihedral Angle (degrees) 

H5-C3-N1-C4 –167.1 178.7 –169.2 –171.6 179.5 –180.0 –178.8 

C3-N1-C4-C5 –175.6 167.0 –176.5 –179.2 170.4 170.1 172.1 

N1-C4-C5-N2 –55.9 –68.6 63.4 64.6 –182.1 –178.5 175.8 

H6-N1-C4-C5 –48.1 –67.6 –50.4 –54.2 –65.0 –64.9 –63.2 

C4-C5-N2-N3 –49.5 80.3 83.5 –172.6 177.1 –79.0 79.6 

H7-C4-C5-N2 178.8 179.7 –62.3 –60.7 52.9 56.6 50.8 

H8-C4-C5-N3 64.2 50.7 –177.8 –176.5 –63.3 –59.7 –65.8 

C5-N2-N3-N4 179.7 168.3 173.9 –179.2 –180.0 –174.0 175.5 

H9-C5-N2-N3 –171.3 –44.1 –39.8 67.4 56.8 161.4 –44.0 

H10-C5-N2-N3 74.0 –160.1 –157.2 –52.5 –62.5 44.8 –160.6 
32

Table A-10. Normal mode frequencies (cm-1) for CPAZ group 11 conformers. 

 Conformer 

Mode A11 B11 C11 D11 E11 F11 G11 H11 I11 J11 L11 

1 24 39 30 32 28 34 36 37 27 29 32 

2 49 62 57 60 67 50 47 51 62 52 41 

3 95 74 80 88 82 80 77 65 84 80 66 

4 138 148 139 131 98 131 134 111 93 149 138 

5 185 173 171 185 153 145 147 210 161 179 178 

6 209 267 225 202 191 245 238 244 232 214 249 

7 302 302 328 292 294 320 318 298 302 304 328 

8 401 394 411 411 346 329 332 333 326 401 401 

9 426 429 433 432 439 441 441 438 437 457 458 

10 519 515 506 507 482 482 482 525 523 533 528 

11 562 557 553 558 549 555 557 557 550 556 556 

12 684 652 658 638 658 677 677 680 656 628 660 

13 723 741 755 760 756 754 756 682 684 723 714 

14 778 779 778 785 777 775 776 755 756 760 761 

15 821 824 816 821 812 812 815 790 790 807 807 

16 841 838 840 842 830 830 829 828 827 841 837 

17 845 843 842 849 843 843 843 842 842 847 841 

18 888 912 892 895 939 927 923 921 937 884 872 

19 952 959 948 947 950 940 941 944 948 946 939 

20 997 986 989 1004 999 991 996 971 971 981 963 

21 1005 1003 1041 1042 1043 1043 1043 1010 1043 1022 1021 

22 1045 1045 1050 1060 1070 1059 1056 1044 1049 1043 1044 

23 1073 1073 1070 1070 1086 1071 1071 1071 1071 1071 1071 

24 1101 1093 1100 1094 1099 1102 1098 1094 1091 1091 1099 

25 1131 1130 1131 1131 1128 1128 1129 1127 1126 1128 1125 

26 1147 1147 1140 1144 1142 1151 1155 1150 1142 1144 1139 

27 1188 1187 1190 1188 1188 1186 1186 1186 1186 1183 1185 

28 1195 1195 1194 1194 1194 1194 1194 1195 1195 1195 1195 

29 1241 1240 1235 1239 1224 1236 1234 1240 1235 1232 1234 

30 1250 1253 1242 1241 1241 1241 1241 1252 1247 1251 1256 

31 1281 1279 1282 1285 1310 1300 1305 1306 1327 1297 1289 

32 1331 1344 1334 1337 1328 1327 1316 1335 1332 1337 1333 

33 1378 1380 1371 1373 1344 1354 1359 1356 1339 1372 1374 

34 1400 1386 1387 1390 1396 1391 1394 1397 1399 1390 1391 

35 1412 1412 1412 1414 1421 1417 1417 1409 1410 1409 1408 

36 1455 1455 1454 1454 1454 1454 1454 1454 1454 1454 1454 

37 1479 1476 1483 1481 1482 1482 1483 1479 1480 1470 1472 

38 1499 1495 1488 1484 1497 1498 1498 1487 1487 1487 1489 

39 1506 1497 1504 1501 1508 1507 1508 1503 1501 1494 1496 

40 1515 1513 1512 1511 1521 1519 1519 1507 1507 1510 1510 

41 2233 2236 2229 2238 2238 2228 2230 2226 2235 2237 2229 

42 2916 2922 2917 2940 2955 2932 2954 3006 2994 3001 3013 

43 3014 3003 3029 3010 2995 3007 3036 3028 3035 3030 3023 

44 3033 3040 3036 3038 3042 3042 3042 3050 3041 3044 3053 

45 3038 3070 3043 3054 3047 3071 3051 3076 3050 3048 3058 

46 3092 3103 3118 3058 3074 3124 3100 3118 3085 3076 3113 

47 3125 3125 3124 3123 3124 3125 3125 3125 3125 3124 3124 

48 3129 3129 3129 3129 3129 3129 3129 3130 3130 3129 3129 

49 3207 3207 3206 3205 3206 3207 3207 3208 3207 3206 3206 

50 3220 3220 3219 3219 3219 3220 3220 3221 3220 3220 3220 

51 3507 3499 3511 3509 3501 3502 3502 3526 3528 3527 3525 
33

Table A-11. Normal mode frequencies (cm-1) for CPAZ group 21 conformers. 

 Conformer 

Mode A21 B21 C21 D21 E21 F21 G21 H21 I21 J21 L21 

1 27 48 25 23 30 38 34 39 28 33 32 

2 56 54 40 38 71 47 53 44 63 43 47 

3 88 76 103 92 78 79 74 71 85 96 92 

4 141 115 107 113 90 94 90 113 93 103 120 

5 199 236 202 184 154 232 224 220 162 178 211 

6 256 259 249 240 260 258 266 244 232 244 238 

7 300 300 339 317 310 292 279 293 302 278 313 

8 408 401 407 403 327 347 354 330 326 389 394 

9 435 445 413 411 419 418 418 437 437 445 444 

10 530 514 505 506 517 517 519 523 523 510 516 

11 559 555 559 551 551 556 558 555 550 554 557 

12 683 649 660 630 650 675 678 677 656 628 655 

13 716 719 716 726 735 728 729 680 684 680 688 

14 774 766 753 762 764 761 762 758 756 763 764 

15 816 813 799 801 797 799 797 791 789 806 803 

16 834 831 837 835 826 827 827 827 827 842 837 

17 838 841 841 848 838 839 838 843 842 847 845 

18 880 902 887 896 937 924 923 919 937 883 876 

19 955 949 952 962 960 946 946 943 948 949 940 

20 972 982 966 967 968 960 966 973 971 973 964 

21 995 990 1043 1041 1043 1040 1040 1009 1044 1020 1009 

22 1048 1044 1053 1057 1068 1052 1050 1044 1049 1041 1042 

23 1075 1075 1069 1068 1073 1072 1072 1072 1071 1068 1070 

24 1096 1091 1088 1087 1092 1092 1093 1091 1091 1095 1085 

25 1130 1132 1116 1121 1131 1132 1131 1128 1126 1127 1132 

26 1145 1139 1130 1128 1137 1145 1141 1155 1142 1141 1145 

27 1187 1185 1189 1189 1183 1189 1189 1186 1186 1187 1187 

28 1197 1196 1193 1194 1195 1196 1195 1195 1195 1195 1196 

29 1236 1239 1241 1241 1234 1237 1237 1240 1235 1240 1240 

30 1266 1264 1262 1246 1257 1262 1261 1252 1247 1248 1254 

31 1291 1303 1314 1319 1327 1315 1309 1313 1327 1311 1303 

32 1335 1347 1338 1349 1331 1331 1332 1330 1332 1335 1332 

33 1377 1377 1376 1379 1343 1356 1355 1359 1339 1379 1378 

34 1399 1386 1388 1383 1390 1386 1390 1395 1399 1386 1390 

35 1415 1415 1417 1416 1420 1417 1417 1408 1410 1407 1406 

36 1456 1455 1456 1454 1455 1455 1455 1454 1454 1454 1454 

37 1488 1481 1480 1479 1485 1482 1482 1479 1480 1472 1470 

38 1492 1482 1485 1480 1493 1491 1492 1487 1487 1479 1483 

39 1496 1493 1489 1492 1504 1505 1505 1504 1501 1492 1495 

40 1507 1505 1507 1506 1509 1509 1510 1507 1507 1508 1509 

41 2231 2234 2226 2234 2237 2228 2228 2227 2235 2234 2228 

42 2918 2936 2937 2952 2959 2940 2959 3024 2994 2984 2997 

43 3011 3035 3005 3001 3018 3039 3036 3033 3036 3014 3015 

44 3030 3036 3039 3051 3040 3042 3041 3052 3041 3025 3055 

45 3050 3071 3053 3056 3057 3074 3056 3070 3050 3077 3086 

46 3123 3101 3123 3064 3080 3123 3124 3101 3085 3098 3098 

47 3124 3125 3124 3123 3123 3124 3129 3125 3125 3123 3124 

48 3128 3130 3133 3129 3128 3129 3130 3130 3130 3128 3129 

49 3207 3208 3206 3204 3206 3206 3206 3208 3207 3205 3206 

50 3221 3222 3225 3219 3219 3219 3219 3221 3220 3218 3219 

51 3534 3544 3531 3526 3538 3536 3535 3528 3528 3523 3523 
34

Table A-12. Normal mode frequencies (cm-1) for CPAZ group 12 conformers. 

 Conformer 

Mode A12 B12 C12 D12 E12 F12 G12 

1 25 44 28 37 28 35 32 

2 45 53 61 48 65 50 51 

3 90 73 76 85 85 84 77 

4 136 129 141 132 90 113 115 

5 178 175 173 197 143 151 150 

6 200 252 228 202 193 241 243 

7 296 290 321 284 296 299 299 

8 400 409 391 389 329 334 333 

9 441 439 436 435 433 436 436 

10 507 502 516 518 491 490 491 

11 562 557 554 556 548 556 557 

12 664 651 657 638 658 675 672 

13 682 694 709 723 711 710 715 

14 763 763 765 767 764 763 763 

15 807 808 808 808 805 803 809 

16 840 828 814 823 809 809 810 

17 846 853 860 868 850 852 848 

18 885 913 893 894 938 921 920 

19 940 940 942 939 943 939 940 

20 988 990 988 992 985 977 978 

21 1004 998 1006 1031 1035 1035 1035 

22 1034 1034 1035 1035 1065 1053 1053 

23 1066 1064 1067 1066 1073 1066 1066 

24 1081 1068 1106 1094 1095 1091 1087 

25 1125 1125 1125 1124 1123 1123 1124 

26 1133 1129 1134 1136 1125 1126 1129 

27 1189 1189 1188 1189 1182 1189 1189 

28 1196 1194 1191 1196 1189 1194 1195 

29 1241 1238 1234 1234 1232 1236 1235 

30 1271 1275 1255 1252 1263 1263 1263 

31 1282 1284 1290 1296 1313 1303 1306 

32 1332 1343 1334 1336 1324 1325 1316 

33 1357 1362 1357 1361 1344 1352 1353 

34 1397 1386 1382 1381 1376 1375 1381 

35 1415 1407 1411 1416 1423 1415 1416 

36 1461 1462 1461 1461 1462 1462 1462 

37 1489 1485 1488 1482 1494 1493 1494 

38 1500 1495 1495 1495 1497 1499 1499 

39 1511 1501 1508 1503 1514 1514 1514 

40 1516 1517 1512 1512 1519 1517 1518 

41 2233 2237 2229 2239 2237 2229 2230 

42 2926 2931 2928 2950 2964 2942 2963 

43 3013 3001 3026 3010 2994 3006 3036 

44 3027 3063 3037 3045 3046 3063 3043 

45 3091 3102 3113 3059 3068 3113 3099 

46 3112 3113 3117 3113 3113 3118 3113 

47 3118 3118 3118 3117 3118 3125 3118 

48 3123 3126 3120 3120 3125 3126 3125 

49 3191 3191 3191 3191 3191 3191 3192 

50 3206 3206 3206 3206 3206 3206 3206 

51 3529 3519 3528 3525 3521 3522 3521 
35

Table A-13. Normal mode frequencies (cm-1) for CPAZ group 22 conformers. 

 Conformer 

Mode A22 B22 C22 X22 D22 E22 F22 G22 

1 27 39 31 20 32 27 36 33 

2 41 52 52 39 45 55 47 50 

3 78 73 88 54 85 82 66 55 

4 137 116 109 92 113 90 99 96 

5 190 208 214 225 175 154 227 213 

6 234 249 235 242 242 239 251 257 

7 310 309 319 289 289 307 281 282 

8 398 393 393 371 383 319 335 336 

9 470 478 457 468 462 439 442 442 

10 503 490 500 482 496 509 508 510 

11 560 555 556 550 553 550 555 558 

12 631 631 649 594 623 625 634 637 

13 691 651 665 648 666 680 690 690 

14 760 756 751 753 750 754 753 753 

15 812 809 802 804 805 793 794 793 

16 825 830 815 813 816 816 818 816 

17 848 843 857 851 859 841 840 840 

18 879 898 890 906 899 940 925 922 

19 942 941 933 937 938 947 943 949 

20 968 978 968 970 970 961 952 952 

21 985 986 1016 993 1018 1034 1022 1022 

22 1034 1035 1035 1035 1033 1049 1037 1037 

23 1069 1068 1066 1066 1064 1067 1068 1067 

24 1085 1079 1096 1087 1095 1097 1096 1095 

25 1133 1128 1112 1119 1118 1127 1127 1125 

26 1138 1130 1133 1129 1131 1131 1139 1136 

27 1191 1189 1188 1188 1188 1184 1189 1189 

28 1193 1191 1191 1190 1192 1191 1191 1193 

29 1241 1242 1245 1246 1243 1238 1243 1242 

30 1275 1270 1256 1262 1251 1259 1262 1261 

31 1285 1297 1312 1307 1317 1330 1317 1311 

32 1335 1346 1334 1353 1341 1334 1334 1332 

33 1375 1371 1377 1376 1373 1343 1356 1361 

34 1395 1388 1384 1381 1387 1375 1376 1375 

35 1404 1399 1401 1397 1405 1414 1407 1410 

36 1462 1462 1462 1461 1461 1462 1462 1462 

37 1489 1479 1479 1475 1475 1487 1486 1487 

38 1495 1492 1487 1484 1478 1496 1495 1495 

39 1501 1494 1496 1493 1495 1504 1505 1505 

40 1512 1510 1513 1510 1515 1511 1510 1510 

41 2232 2235 2227 2234 2235 2237 2228 2228 

42 2927 2942 2940 3004 2971 2972 2952 2971 

43 3011 3020 3012 3025 2998 3010 3028 3036 

44 3051 3073 3054 3050 3053 3051 3074 3057 

45 3110 3100 3112 3090 3062 3079 3114 3114 

46 3114 3114 3117 3113 3111 3114 3119 3115 

47 3119 3118 3122 3118 3116 3119 3122 3119 

48 3127 3121 3153 3131 3161 3123 3125 3126 

49 3192 3193 3191 3193 3190 3193 3193 3193 

50 3207 3208 3206 3207 3205 3208 3208 3208 

51 3567 3578 3556 3584 3558 3571 3570 3568 
36

Table A-14. Normal mode frequencies (cm-1) for CPAZ group 13 conformers. 

 Conformer 

Mode A13 B13 C13 D13 E13 F13 G13 

1 26 28 26 23 27 26 23 

2 31 56 41 40 49 46 43 

3 88 81 91 83 82 81 80 

4 142 126 135 139 91 107 101 

5 176 208 188 180 143 154 159 

6 206 254 219 218 189 255 246 

7 293 289 320 281 319 289 290 

8 377 398 385 385 368 390 389 

9 454 438 440 439 395 399 399 

10 547 548 550 548 522 522 523 

11 562 559 557 559 548 555 557 

12 682 652 658 641 661 674 673 

13 694 719 729 734 737 736 739 

14 757 757 762 767 757 755 756 

15 797 793 798 797 799 799 799 

16 829 815 818 821 806 805 811 

17 845 844 843 854 828 831 829 

18 873 894 880 880 911 909 913 

19 929 943 927 928 946 930 923 

20 994 991 984 999 995 985 990 

21 1006 995 1029 1033 1034 1034 1034 

22 1034 1036 1052 1061 1060 1051 1050 

23 1069 1065 1068 1067 1067 1066 1066 

24 1087 1077 1090 1077 1094 1072 1070 

25 1114 1106 1108 1112 1111 1124 1124 

26 1135 1130 1134 1134 1130 1132 1134 

27 1189 1188 1188 1189 1186 1189 1189 

28 1195 1191 1196 1196 1191 1193 1195 

29 1247 1251 1236 1238 1226 1237 1235 

30 1270 1262 1267 1269 1267 1265 1266 

31 1287 1285 1284 1285 1314 1302 1309 

32 1330 1345 1332 1338 1331 1331 1317 

33 1387 1383 1377 1377 1344 1354 1360 

34 1401 1392 1395 1399 1411 1406 1408 

35 1410 1415 1410 1412 1415 1412 1412 

36 1463 1463 1464 1463 1463 1463 1463 

37 1491 1485 1488 1482 1495 1496 1497 

38 1503 1496 1499 1499 1499 1500 1501 

39 1513 1505 1509 1505 1519 1516 1518 

40 1524 1526 1522 1522 1525 1525 1525 

41 2234 2237 2230 2239 2238 2228 2230 

42 2913 2927 2917 2941 2960 2937 2957 

43 3014 3003 3031 3011 2996 3009 3039 

44 3043 3085 3050 3059 3052 3085 3064 

45 3092 3102 3119 3063 3087 3120 3102 

46 3118 3119 3120 3120 3120 3127 3120 

47 3129 3128 3127 3127 3128 3129 3129 

48 3134 3142 3134 3134 3139 3139 3138 

49 3196 3196 3197 3197 3197 3197 3198 

50 3213 3211 3212 3212 3212 3212 3213 

51 3511 3503 3510 3508 3504 3505 3503 
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 ADELPHI MD 20783-1197 

 1 DIRECTOR 

 US ARMY RESEARCH LAB 

 AMSRD ARL CS IS R 

 2800 POWDER MILL RD 

 ADELPHI MD 20783-1197 

 3 DIRECTOR 

 US ARMY RESEARCH LAB 

 AMSRD ARL CI OK TL 

 2800 POWDER MILL RD 

 ADELPHI MD 20783-1197 

 3 DIRECTOR 

 US ARMY RESEARCH LAB 

 AMSRD ARL CS IS T 

 2800 POWDER MILL RD 

 ADELPHI MD 20783-1197 

ABERDEEN PROVING GROUND

 1 DIR USARL 

 AMSRD ARL CI OK TP (BLDG 4600) 
NO. OF 

COPIES ORGANIZATION 

38

 29 DIR USARL 

 AMSRD ARL WM BD 

 W R ANDERSON 

 R A BEYER 

 A L BRANT 

 S W BUNTE 

 C F CHABALOWSKI 

 L M CHANG 

 T P COFFEE 

 J COLBURN 

 P J CONROY 

 B E FORCH 

 B E HOMAN 

 S L HOWARD 

 S KARNA 

 P J KASTE 

 A J KOTLAR 

 M LEADORE 

 C LEVERITT 

 R LIEB 

 K L MCNESBY 

 M MCQUAID 

 A W MIZIOLEK 

 J B MORRIS 

 J A NEWBERRY 

 M J NUSCA 

 R A PESCE RODRIGUEZ 

 G P REEVES 

 B M RICE 

 R C SAUSA 

 A W WILLIAMS