bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory of space-charge-limited current with one blocking electrode
Authors: Bonham JS , Jarvis DH
Published: September 2010

Numerically calculated
space-charge-limited current-voltage curves are presented for an insulator with
one ohmic electrode (infinite injected charge density) and one blocking
electrode (finite injected charge density). Charge-carrier diffusion is included,
and traps in the insulator are assumed to be absent, shallow, or exponentially
distributed in energy. The transition from bulk to surface limitation of the
current (when the charge density is large but finite at the injecting
electrode) is discussed with reference to the validity of the diffusion-free
theory. A modification of the constant-field approxi-
mation is shown to give a good description of the
current-voltage curve when the injected charge density at the blocking
electrode is small, and the current lies well below the purely space-charge-limited
current which would flow if both electrodes were ohmic.
The crystal structure of 1α,4aβ,6β,9aα-Tetrahydroxy-4a,5aα,9a,10aβ-tetrahydrodibenzo[b,e][1,4]dioxin-2,7(1H,6H)-dione - A dimeric oxidation product of quinol
Authors: Cannon JR , Patrick VA , White AH
Published: September 2010

A single-crystal structure
determination has revealed that the product obtained by oxidation of quinol
with sodium chlorate and osmium tetroxide and crystallized from dimethyl
sulfoxide is a solvate of 1α,4aβ,6β,9aα-tetrahydroxy-4a,5aα,9a,10aβ-tetrahydrodibenzo[b,e][1,4]dioxin-2,7(1H,6H)-dione. The crystals of C12H12O8,2(CH3)2SO
are monoclinic, P21/n, a 7.859(5), b 9.774(7), c 13.14(1) Ǻ,
β 93.08(6)°, Z 2, with each molecule of the dione centred on a
crystallographic centre of symmetry. The solvent molecules are disordered. The
structure was refined by least squares to a residual of 0.046 for 1361
'observed' reflections.
The structure and synthesis of cytokinin metabolites. III. 13C N.M.R. of cytokinin glycosides
Authors: Duke CC , Macleod JK
Published: September 2010

The 13C N.M.R.
spectra of the cytokinins (1)-(3) and cytokinin glycosides (4)-(11) are
reported and complete assignments made by correlation with related compounds
and with the aid of deuterium labelling. The results show that previously
derived 13C N.M.R. correlations on simpler purine derivatives can be
extended to the cytokinin glucosides for the determination of the substitution
positions on the adenine ring. As well, the structure of the substituents and
the stereochemistry of the N-glu-cosyl linkages can
be confirmed from 13C chemical shift values.
Nucleophilic alkenes. VI. Addition of 1,1-dimethoxyethene to 1,2-naphthoquinones and 9,10-phenanthraquinones
Authors: Cameron DW , Deutscher KR , Feutrill GI
Published: September 2010

1,2-Naphthoquinone
underwent 1 : 2-addition of 1,1-dimethoxyethene to give 1,3-dimethoxy-9,10-phenanthraquinone,
a process having analogy in the 1,4-quinone series. 1,2-Naphthoquinonesand 9,10-phenanthraquinones
also underwent direct attack at the carbonyl carbon. This latter process has no
observed analogy in the 1,4-quinone series and presumably is assisted by
unfavoured juxtaposition of the two carbonyl groups. Mixtures of products were
generally obtained and five different reaction types were identified-vinylogous
1 : 1- and 1 : 2-addition, direct 1 : 1- and 1 : 2-addition, and dioxole
formation through bridging of the carbonyl oxygens.
The conformations as solutes of 2-Halogenomethyl- and 2-Cyanomethyl-oxirans
Authors: Aroney MJ , Calderbank KE , Stootman HJ
Published: September 2010

Electric dipole moments and molar Kerr constants are reported for the substituted oxirans (A; X = H, F, Cl, Br, I or CN). The data are analysed to obtain information on the relative abundances of conformational forms, each of which has a staggered arrangement of the CH2X and oxiran groups.
The synthesis and mass spectra of some Dihydrofuro[2,3-b]pyridines
Authors: Ducker JW , Williams BK
Published: September 2010

The synthesis and mass
spectra of the dihydrofuropyridines (1) are reported.
Polarization at the (U0.7Y0.3)O2+x/YSZ interface by impedance dispersion analysis
Authors: Badwal SPS , de Bruin HJ
Published: September 2010

UO2+x. and Y2O3
form fluorite-type solid solutions (U2Y1-z)O2+x,
which show promise as electrode materials for high-temperature fuel or electrolysis
cells. The impedance dispersion behaviour for one such composition has been
studied in cells of the type (U0.7Y0.3)02+x/YSZ/(U0.7Y0.3)O2+x,
in air, at temperatures between 500 and 900°C, and in the frequency range 5
Hz-500 kHz. The semi-circular arc due to electrode dispersion in the complex
impedance plane is depressed substantially below the real axis. Simulation
calculations show such behaviour to be due to a strong frequency dependence of
the resistor(s) in the equivalent circuit for the electron-transfer reaction.
We attribute such behaviour to a complex series of reaction steps at the
electrode/electrolyte interface.
Circular dichroism spectra of tetraamminecobalt(III) complexes of amino alcohols
Authors: Hawkins CJ , Lawrance GA , Palmer JA
Published: September 2010

The circular dichroism
spectra are reported for tetraamminecobalt(III) complexes with the chiral amino
alcohols 2-aminopropan-1-ol, 2- aminobutan-1-ol, 1-aminopropan-2-ol,
2-amino-1-phenyl-ethanol, ψ- ephedrine and ephedrine with the alcohol
groups protonated (OH) and deprotonated (O-). The solvent dependence of the
chemical shifts of the NH protons was investigated to determine the effects of
stereoselective solvation on the circular dichroism, but, in contrast to some
other related systems, the chemical shift difference between the two NH2
protons was relatively insensitive to solvent. Consistent with this, the
circular dichroism spectra of the tetraphenylborate salts of the deprotonated
complexes were found not to be markedly dependent on solvent. Tetraammine-{(-)-ψ-ephedrine)cobalt(III)
and tetraammine{(-)- ephedrine}cobalt(III) were found to have the same signs of
Cotton effects for the various d-d transitions, whereas bis{(-)-ψ-
ephedrine}copper(II) and bis{(-)-ephedrine}copper(II) had opposite signs. This
has been explained in terms of different conformer populations in the
cobalt(III) and copper(II) systems.
Crystal structure of a polychloroquinone soil pigment
Authors: Cameron DW , Raston CL , White AH
Published: September 2010

The crystal structure of
the title compound, C20H4Cl6O5,C6H6,
has been determined by single-crystal X-ray diffraction at 298 K. Crystals are
monoclinic, C2/c, a 7.258(4), b 19.530(7), c 17.027(11) Ǻ, β
93.59(3)°, Z 4. Both pigment and solvent molecules are located about crystallographic
2 axes; the pigment molecule is considerably distorted as a result of
interaction between substituent chlorine atoms on adjacent rings.
Isomerizations akin to the Dimroth rearrangement. IV. Formation of simple s-Triazolo[1,5-c]pyrimidines via their [4,3-c] isomers
Authors: Brown DJ , Nagamatsu T
Published: September 2010

Pyrimidin-4-ylhydrazines
and simple orthoesters are used in combination (1) to give N-ethoxyalkyl-idene-N'-pyrimidinylhydrazines (2) and thence
s-triazolo[4,3-c]pyrimidine (3a) and its 3-, 5-, 7- or 8-alkylated derivatives
(3b-s). In glacial acetic acid, these undergo rearrangement into the
corresponding s-triazolo[1,5-c]pyrimidines (5) via the
acylaminoalkenyltriazoles (4); in aqueous buffers, these reactions stop at the
triazoles (4) except in the presence of a 7-methyl group which stimulates completion
of the sequence. The ring-fission step, (3) → (4), is retarded markedly
by 5- and/or 8-methyl groups but accelerated slightly by 3- and/or 7-alkyl
groups; the slower ring-fission of triazolo[1,5-c]-pyrimidines (5) to the same
triazoles (4) is retarded by 2-, 5- or 8-alkylation and precluded totally by a
7-methyl group. The recorded u.v. and N.M.R. spectra afford a ready means of
distinguishing between the systems (3)-(5).
The base-catalysed equilibration of 6α-Nitrocholest-4-ene and 6β-Nitrocholest-4-ene
Authors: Pinhey JT , Smith GC
Published: September 2010

Treatment of 6β-nitrocholest-4-ene
with a catalytic amount of sodium methoxide in methanol gave an equilibrium
mixture which contained the starting material and the 6α-epimer in a 1 : 1
ratio. The unusual stability of the 6β-epimer is explained by electronic
factors.
Ion-molecule reactions of formic acid. II. Rearrangement reactions
Authors: Freeman CG , Harland PW , McEwan MJ
Published: September 2010

Rate coefficients for a
number of rearrangement reactions of positive ions with HCOOH are reported.
These reactions may be represented by the general equation �������������������������� Y+ +
HCOOH → products
Most reactant ions resulted
in the fragmentation product HCO+ and five reactant ions, N+,
O+, CN+, N2+ and CO+,
were observed to have rate coefficients much greater than predicted by the ADO
model. An explanation for the high rates observed for these reactant ions is
proposed and involves dissociative charge transfer by a non-orbiting
electron-jump mechanism.
An infrared investigation of Pyrrolidine-2-thione and -2-selenone
Authors: Devillanova FA , Verani G
Published: September 2010

Pyrrolidine-2-thione and
-2-selenone together with their N-deutero and S- and Se-methiodide derivatives
have been studied by i.r. spectroscopy over the range
4000-200 cm-1. C=S and C=Se contribute to the bands at around 1000
cm-1 and below 600 cm-1. In pyrrolidine-2-selenone, the
band at 1005 cm-1 has been attributed to v(CSe).
This value is the highest wave number for all similar pentaatomic rings, which
we have previously investigated, and indicates a greater double-bond character
in CSe. In the low-frequency region two bands at 497
and 334 cm-1 in pyrrolidine-2- thione and two others at 352 and 280
cm-1 in the selenium analogue are undoubtedly attributable to the C=S
and C=Se modes respectively.
Carbon-13 N.M.R. chemical shifts and rotational barriers of ortho-substituted N,N-dimethylbenzamides
Authors: Fong CW , Lincoln SF , Williams EH
Published: September 2010

The barriers to rotation
about the carbon-nitrogen bond and the carbon- 13 N.M.R. chemical shifts of a
series of 2-substituted N,N- dimethylbenzamides have been measured. The
substituent effects have been examined by a multi-substituent parameter method
incorporating a steric effect parameter. The barriers to rotation are subject
to a large steric effect, whilst the carbon-13 chemical shifts of the carbonyl
group and the methyl groups are dominated by the resonance effect.
Stereochemical studies. IV. The role of carbocations in the oxidation of alkylhydrazines
Authors: McLean CD , Middleton S
Published: September 2010

A study of the oxidation of
two neopentylhydrazines by iodine in the presence of base has shown that
carbocations are only involved to a minor extent as intermediates in alkyl
iodide formation, but are likely to be involved to a considerable extent in the
formation of alkenes and alcohols. A comparison is made between the course of
oxidation of a given alkylhydrazine and deamination of the corresponding amine.
Saponins of Acacia pulchella
Authors: Alexander R , Croft KD , Kagi RI , Shea S
Published: September 2010

Acid hydrolysis of the
saponins isolated from the roots of Acacia pulchella R. Br, gave two triterpene
aglycones of known structure and a mixture of monosaccharides. The triterpenes
have been identifiedas oleanolic acid (1) and
echinocystic acid (3). The monosaccharide mixture contained glucose, galactose,
arabinose, xylose and rhamnose. Preliminary results of the effects of the
saponin fraction upon the pathogenic fungus Phytophthora cinnamomi Rands. are reported.
Halogenated Terpenoids. XVI. The Tetrabromides of γ-Terpinene
Authors: Carman RM , Maynard JKL
Published: September 2010

Four tetrabromo
compounds, (1RS,6RS,8RS)-1,6,8,9-tetrabromo-p-menth-3-ene (3), its (8SR) isomer (6), (1RS,2RS,4SR,SRS)-l,2,4,5-tetrabrorno-p-menthane (10), and (1RS,2RS,4RS,5SR)-
1,2,5,8-tetrabromo-p-menthane (7)
together with the dibromide (1RS,6RS)-1,6-dibromo-p-menth- 3-ene (11), are obtained from
the bromination of γ-terpinene.
The Measurement of the Apparent Nuclear Spin-Spin Relaxation Times of N.Q.R. Signals in the Very-High-Frequency Region
Authors: Bryant PJ , Hacobian S
Published: September 2010

The Doolan-Hacobian
n.q.r. double pulse detection technique is described
for the measurement of n.q.r, apparent spin-spin
relaxation times as applied to a v.h.f. lecher line
super-regenerative spectrometer. Results are presented for the linewidths of
the 79Br and 81Br resonances in p-dibromobenzene. It was found that
crystal-field inhomogeneities produce significant
broadening of the n.q.r. signal.
Fluorescence Decay of Pyrene in a Hydrogenated Pyrene Matrix
Authors: Harris CM , Selinger BK
Published: September 2010

Pyrene, 4,5-dihydropyrene and 4,5,9,10-tetrahydropyrene
have been found to form a true solid solution over a range of composition. The
measured fluorescence decay lifetime of pyrene in a hydrogenated pyrene matrix
has been found to depend on the wavelength at which the emission is monitored,
but not on the wavelength of excitation.
A Luminescent Probe Study of Water/Acetonitrile Mixtures
Authors: Easteal AJ
Published: September 2010

Luminescence spectra for
1.0 × 10-2 mol dm-3 solutions of salicylic acid in water,
acetonitrile and water/acetonitrile
mixtures have been determined. In the wavelength range 300-600 nm, all spectra
showed a single broad emission band. The variations of the wavelength of
maximum luminescence intensity (λmax)
and luminescence band half-width (Δ�) with solvent composition
are similar to the composition dependence of these parameters observed
previously for solutions of salicylic acid in water/alcohol mixtures. The
invariance of Δ� with acetonitrile
content up to approximately 15 mole% supports earlier conclusions that up to c.
15 mole% acetonitrile is accommodated within cavities
in the water structure. The rapid increase in near 15 mole% acetonitrile
provides further evidence for a progressive destruction of the water structure
as the acetonitrile content is increased beyond c. 15
mole%.
Crystal Structure of Disodium(I) cis-Bis(ethane-1,2-diamine)disulfitocobaltate(III) Perchlorate Trihydrate
Authors: Raston CL , White AH , Yandell JK
Published: September 2010

The crystal structure of
the title compound, Na2C104 [CO(C2N2H8)2(SO3)2],3H2O,
has been determined by single-crystal X-ray diffraction at 295(1) K and refined
by least squares to a residual of 0.033 for 2693 'observed' reflections.
Crystals are monoclinic, P21/c, a
16.271(3), b 12.298(2), c 9.567(2) �, β 105.85(1)�, Z 4.
The Co-S distances differ significantly, probably a consequence of interaction
of the sulfite oxygen atoms with adjacent sodium ions [Co-S, 2.206(1), 2.233(1)
�]; the Co-N distances trans to the
sulfite groups are significantly longer [2.015(3), 2.003(4) �] than those trans to each other [1.964(4), 1.959(3) �].
Crystal Structure of Sodium O,O'-Nitritonitroargentate(I)
Authors: Skelton BW , White AH
Published: September 2010

The crystal structure of
the title compound, NaAg(NO2)2,
has been determined by single-crystal X-ray diffraction at 295(1) K and refined
by full-matrix least squares to a residual of 0.043 for 449 'observed'
reflections. Crystals are orthorhombic, space group Fd2d, a 7.913(2), b
10.721(2), c 10.857(3) �, Z 8. The
structure is closely related to that of sodium and silver nitrites; the silver
environment is dominated by the 'linear' coordination of a nitro group (Ag-N
2.25(2) �) and a 'chelating' pair of oxygen atoms from another NO2-
species (Ag-O 2.422(8)�), the O2N-Ag-O2N group containing
a crystallographic 2 axis.
Synthesis of Orthotrithioformates and Related Compounds. Carbanion Formation and Evaluation for 1,4 Addition Reactions with α,β-Unsaturated Ketones
Authors: Smith RAJ , Lal AR
Published: September 2010

The syntheses of potential α-sulfur-substituted
carbanion precursors (2a-h) are reported and the results of their subsequent
reactions with strong bases are presented. The relatively stable carbanions
(3a-d) were made to react with a variety of α,β-unsaturated ketones
and the yields of 1,4 and 1,2 addition products were determined.
Towards the 6,11-Dioxasteroids
Authors: Davis M , Pettett M
Published: September 2010

A synthetic route from m-methoxyphenol
to the tetracycles (cis-13,14)-3-methoxy-6,11-dioxa-9β,13ζ14ζ-estra-1,3,5(10)-triene (7; X = H2) and (cis-13,14)-3-methoxy-6,11-dioxa-9/β,13ζ,l4ζ-estra-1,3,5(10)-trien-12-one
(11) is described in which all the skeletal carbon atoms except the oneat position 7 are joined
together in the first step.
Relationship Between Dipole Moments and Inductive Substituent Constants
Authors: Poh B
Published: September 2010

A linear relationship
between μ/d (where μ is the
C-X bond dipole moment and d is a
distance parameter) and the inductive substituent constant, σ1
for substituted acetic acids, XCH2COOH, is derived from a
combination of Taft and Kirkwood-Westheimer equations.
This linear relationship is similar to the empirical relationship relating μ/d
and σ1, observed in monosubstituted alkanes.
Bis(thioimidates): Structure and Reactivity
Authors: Ewin G , Hill JO
Published: September 2010

Dimethyl N,N'-ethylenebis(thiobenzimidate),
dimethyl N,N'-trimethylenebis(thiobenzimidate),
N,N'-di[morpholino(phenyl)methylene]ethane-1,2-diamine,
N,N'-di[morpholino(phenyl)methylene]-
propane-1,3-diamine, and the zinc complex of dimethyl N,N'-ethylenebis(thiobenzimidate) have been synthesized and
characterized by melting point, microanalysis, and infrared and mass spectral
analysis. The N.M.R. spectra of the thiobenzimidates are discussed in terms of
the various possible isomers resulting from restricted rotation within the
thioimidate group.
Synthesis of some 3-Nitro-L-tyrosine peptides by means of active polyester intermediates derived from the nitrophenol side chain
Authors: Stewart FHC
Published: September 2010

The action of N,N'-dicyclohexylcarbodiimide
on amino-protected derivatives of 3-nitro-L-tyrosine results in
self-condensation with formation of active polyester intermediates, which
proved to be useful coupling components for the synthesis of peptides containing
this amino acid. The products obtained include the pentapeptide
precursor of a 3-amino-L-tyrosine analogue of the opiate agonist leucine-enkephalin.
Excess Volumes and Isentropic Compressibilities of Binary Mixtures of an Alcohol and Isobutyl Methyl Ketone
Authors: Reddy KS , Naidu PR
Published: September 2010

Excess volumes and
isentropic compressibilities for the binary mixtures
of propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol with isobutyl methyl ketone
were determined at 303.15 and 313.15 K. Excess volumes of the four mixtures are
negative over the whole range of compositions at both the temperatures.
Deviations in isentropic compressibility are also negative in all cases, except
for propan-1-ol + isobutyl methyl ketone. In this system, the deviation in
isentropic compressibility shows an inversion in sign at 303.15 K.
An Improved Synthesis of 5α-Androst-3-en-17β-yl Acetate by the Caglioti Reaction
Authors: Cambie RC , Rutledge PS , Scott DW , Woodgate PD
Published: September 2010

A study of the Caglioti reaction (B2H6/Ac2O)
on testosterone has led to an improved procedure for the formation of 5α-androst-3-en-17β-yl
acetate.
Coordinating Properties of Aromatic and Aliphatic Sulfur with Bivalent Metals in Aqueous Solution. A Calorimetric Study
Authors: Aruga R
Published: September 2010

Heats and entropies of
complex formation of the thiophen-2-carboxylate ion with Ni2+, Cu2+,
Zn2+ and Cd2+ have been determined by direct calorimetry, the formation constants being known from the
literature. The measurements were carried out in aqueous medium at 25�C and an
ionic strength of 1. The values of the thermodynamic quantities for
thiophen-2-carboxylate, compared with those for (ethylthio)acetate
and (phenylthio)acetate obtained previously, indicate a greater tendency for
aromatic sulfur to form bonds with the above metals than for aliphatic sulfur.
The causes of this behaviour are discussed.
Studies in the Tricyclooctane Series. I. Dehydrohalogenation of Some Bis-halogenocarbene Adducts of Cyclohexadienes
Authors: Banwell MG , Halton B
Published: September 2010

Reaction between
4,4,8,8-tetrachloro-cis-transoid-cis-tricyclo[5,1,0,03,5]octane
(1d) and potassium t-butoxide leads to the (E)- and (Z)-β-t-butoxy-4-chlorostyrenes (8a,b). The epimeric
4,4,8-trichloro analogues (1e,f) behave similarly to
give (E)-β-t-butoxystyrene
(8c) as the sole isolable product in low yield. Under the same conditions the
corresponding tri- and tetra-chloro-cis-transoid-cis-tricyclo[5,1,0,02,4]octanes (7d-f) yield complex product mixtures. Evidence is
presented which suggests the non-involvement of halogenocyclooctatetraenes
in these reactions.
Oxidation of Copper Sulfides in Aqueous Ammonia. I. Formation of Sulfur
Authors: Filmer AO , Parker AJ , Wadley LGB
Published: September 2010

Elemental sulfur, rather
than sulfate or thiosulfate ions, is the major
sulfur-containing product when CuS or Cu2S
are oxidized at temperatures below 40� with oxygen in a large excess of aqueous
ammonia containing ammonium sulfate at pH 10-10.5. At temperatures above 60�,
or in solutions containing low proportions of ammonia or ammonium sulfate, very
little sulfur is formed. Higher partial pressures of oxygen lead to higher
proportions of sulfur. These observations are explained in terms of concurrent
and consecutive reactions involving copper polysulfides.
The high proportion of ammonia to soluble copper ions which is required imposes
some practical limitations on any potential leaching process aimed at producing
sulfur. Proportions of sulfur from metal sulfide oxidation in aqueous ammonia
decrease in the series of metal sulfides, Cu2S > CuS > NiS > FeS > ZnS > CoS. Some aspects of the chemistry of sulfur in aqueous
ammonia are discussed.
Cyclopentadienyl-ruthenium and -osmium Chemistry. VII. Complexes Containing Nitriles, Tertiary Phosphines or Phosphites Formed by Addition or Displacement Reactions
Authors: Ashby GS , Bruce MI , Tomkins IB , Wallis RC
Published: September 2010

Cationic complexes were obtained from RuCl(PPh3)2(η-C5H5) and a variety of nitriles, tertiary
phosphines and phosphites. Nitriles afforded the cations [Ru(NCR)(PPh3)2(η-C5H5)]+ (R = CH2Cl,
CH2 = CH2 CH2 = CCl, Ph, C6F5, CH2CN, CH2CO2Et, 2-NCC,6H4, 2-NCC6F4 or 4-NH2C6H4) and
{R[(CN)Ru(PPh3)2(η-C5H5)]2}2+ (R = 1,2-C2H4, 1,3-C6H4 or 1,4-C6F4). Displacement of PPh3
from RUCI(PPh3)2(η-C5H5) or OsBr(PPh3)2(η-C5H5) by tertiary phosphines or phosphites has given
the complexes Rul(L2)(η-C5H5) [L = P(OMe)3; L2 = dppm, dppe], OsBr(L)(PPh3)(η-C5H5)
[L = P(OMe)3, P(OPh)3] and OsBr(L2)(η-C5H5) [L = P(OMe)3, P(OPh)3; L2 = dppm]. The
cationic complexes {Ru(PPh3)2[P(OMe)3](η-C5H5)}+, [Ru(L2)(PPh3)(η-C5H5)l+ (L2 = dppm or
dppe), {[M(PPh3)2(η-C5H5)]2(L2)}2+ [M = Ru, L2 = C2(PPh2)2; M = Os, L2 = dppe], [Ru(L3)-
(η-C5H5)]+ [L = P(OMe)3; L3 = MeC(CH2PPh2)3 or EtC(CH2PPh2)3] and [OS(NCMe)(PPh3)2
(η-C5H5)]+ are also described.
Syntheses of Haptens Related to the Benzenoid and Indole Portions of Sporidesmin A; 13C N.M.R. Spectra of Indole Derivatives
Authors: Blunt JW , Erasmuson AF , Ferrier RJ , Munro MHG
Published: September 2010

The syntheses of
2-amino-5-chloro-3,4-dimethoxybenzyl alcohol (2) and 5-chloro-6,7-dimethoxy-N- methyl-1H-indol-3-yloxoacetic acid (22), potential haptens
related to the benzenoid and indole portions of the mycotoxin sporidesmin, are
described. 13C N.M.R. assignments for the latter and ten related indole compounds are given.
Cyclophanes. XIII. Approaches to the Synthesis of Corannulene
Authors: Davy JR , Iskander MN , Reiss JA
Published: September 2010

The
dithia[3,3](2,7)naphthalenoparacyclophanes (12) and (13) were synthesized and
then ring-contracted either by Wittig or Stevens rearrangements to the
[2,2]cyclophanes (17), (18) and (20).Elimination of the sulfur
functional groups gave [2,2](2,7)naphthalenoparacyclophane-1,11-diene(6) and
1,12-dimethy1[2,2](2,7)naphthalenoparacyclophane-1,11-diene (7) which were
characterized and their stereochemistry in solution determined from their 1H
N.M.R. spectra. The [2,2]cyclophane (8) was prepared by photochemical
elimination of sulfur from the dithiacyclophane (12) in trimethyl phosphite.
Attempts to convert the cyclophanes (6), (7) and (8) into corannulenes are
described.The stereochemistry of
compounds (8) and (13) is also discussed together with the effect of the methyl
groups in cyclophanes such as compound (13) on the subsequent ring-contraction
and elimination reactions.
Luminescence of Salicylic Acid in Concentrated Aqueous ZnCl2 + LiCl Solutions
Authors: Easteal AJ
Published: September 2010

The luminescence of 1.158 ×
mol dm-6 solutions of salicylic acid in (1-X)ZnCl2,4H2O
+ XLiCl,4H2O has been
investigated. The luminescence band half-width (Δ�) and (λmax)wavelength of maximum
intensity (λmax) have been determined
as a function of the relative proportions of the components ZnCl2,4H2O
and LiCl,4H2O. Both Δ� and λmax
are invariant or almost invariant within experimental precision in the
approximate composition regions O ≤ X ≤ 0.4 and 0.6 ≤ X ≤
1. λmax shifts to shorter wavelength
and Δ� decreases sharply, in the approximate composition range
0.4 ≤ X ≤ 0.6. The results are interpreted
as indicating that addition of LiCl,4H2O to ZnCl2,4H2O
causes initially depolymerization of species in which
both water and chloride are coordinated to zinc, and that replacement of H2O
by Cl- in the primary coordination sphere of zinc
begins to occur at about X = 0.4 and is complete at a composition close to that
corresponding to the tetrachlorozincate anion
stoichiometry.
Electron-Transfer Reactions in Non-Aqueous Media. IV. A Temperature-Dependence Study of the Reduction of CoCl(NH3)52+ by Iron(II) in N,N-Dimethylformamide
Authors: Beckham KR , Watts DW
Published: September 2010

A detailed study has been
made of the temperature dependence of the rate of reduction of CoCl-(NH3)52+
by iron(II) in N,N-dimethylformamide. The observed rate constants (kobs)
for this reaction are complex functions of an equilibrium constant (K) for the formation of a bridged
intermediate, the rate constant for electron transfer in this bridged
intermediate (k), and the iron(II)
concentration. From studies of the dependence of kobs on iron(II)
concentration at five temperatures the temperature dependences of both K and k have been resolved, yielding
respectively ΔH� -20k�12 kJ mol-1,
ΔS� -44�40 J K-1 mol-1 and ΔH* 107�4 kJ mol-1, ΔS*
57�16 J K-1 mol-1. The results are interpreted in terms
of a bridged intermediate in which the iron atom is tetrahedrally coordinated.
The Chemistry of Aryllead(IV) Tricarboxylates. Synthesis
Authors: Bell HC , Kalman JR , Pinhey JT , Sternhell S
Published: September 2010

Syntheses of a number of
aryllead(IV) tricarboxylates are reported. Some of these compounds have been
prepared by the known methods of direct plumbylation, and reaction of a
diarylmercury compound with lead tetraacetate in a halogenated acetic acid. Two
further methods of preparation of aryllead tricarboxylates are reported and the
scope of each of these has been explored. The methods involve the reaction of
an arylmercury trifluoroacetate with lead tetrakistrifluoroacetatein trifluoroacetic acid,
and the reaction of aryltrimethylsilanes with lead tetraacetate in
trifluoroacetic acid.
Encephalitogenic Peptides: Synthesis and 13C N.M.R. of a Pentapeptide Fragment of Myelin Basic Protein of the (65-74) Region
Authors: Pasaribu SJ
Published: September 2010

The synthesis, by stepwise
conventional method, of a fully protected pentapeptide, Boc-Ser(OBzl)-
Leu-Pro-Gln-Lys(N8-Cbz)-OBzl, a fragment of the MBP 65-74 region, is
described. 13C N.M.R. of the intermediates are discussed, and it was
observed that proline gave rise only to the trans-
conformation. The benzyl ether protecting group of the serine side chain was
found to cause the β-carbon to
resonate at a lower field, whereas the α-carbon
experienced an upfield shift.
The Synthesis of Methoxy- and Hydroxy-Substituted Cinnamaldehydes and Their Corresponding Epoxides. II. The Epoxides
Authors: Olstein R , Stephenson EFM
Published: September 2010

The formation and stability
of the epoxides of 4-hydroxy-3,5-dimethoxycinnamaldehyde, 3,4,5-
trimethoxycinnamaldehyde, 4-hydroxy-3-methoxycinnamaldehyde and
3,4-dimethoxycinnamaldehyde and the diacetates of these aldehydes have been
studied under a variety of epoxidation conditions. m-Chloroperbenzoic acid in chloroform was the most successful
epoxidizing agent. The epoxidation of 3,4,5-trimethoxycinnamylidene and
4-methoxycinnamylidene diacetates was followed, in each case, by ring cleavage
of the newly formed epoxide diacetate. The epoxidation of 4-acetoxy-3,5-
dimethoxycinnamylidene and 4-acetoxy-3-methoxycinnamylidene diacetates
proceeded normally with the formation of the corresponding epoxides. Hydrolysis
of these epoxides with magnesium hydroxide suspension gave a mixture of
cleavage products, e.g. the α,β-dihydroxy aldehydes (26) and (27)
from 4-acetoxy-3-methoxycinnamylidene diacetate epoxide.
Alkaloids of Bellendena montana
Authors: Bick IRC , Gillard JW , Leow H
Published: September 2010

Fourteen alkaloids have
been isolated from Bellendena montana,
a monotypic proteaceous plant endemic in Tasmania. The structures of ten of
these, bellendine (1), isobellendine (2), darlingine (3),5,11-dihydroisobellendine
(5), 2,3-dihydrobellendine (6), 2,3-epidihydrobellendine (7),
2,3-dihydrodarlingine(8), 3α-acetoxy-6β-isobutoxytropane (9), 6β-acetoxy-3α-isobutoxytropane
(10) and 3α-acetoxy-6β-hydroxytropane
(11), have been established.
Model Calculations of Isotope Effects. III. Isotope Effects in Hydrogen Transfer Reactions, and Transition State Force Fields
Authors: McLennan DJ
Published: September 2010

Model calculations of
kinetic isotope effects for the reactions:

C2H6+·CH3
→ ·C2H5+CH4

CH4 + ·CF3
→ ·CH3+CHF3

are reported. Transition
state geometries were those calculated by Dewar and coworkers using the MNDO
semiempirical method. Transition state force fields were formulated from
empirical expressions for stretching, bending, linear bending and interaction
valence force constants by using bond orders as disposable parameters. Although
it proved impossible to assign a best force field to either reaction, the
calculated isotope effects generally were in satisfactory agreement with
experiment, and were better than those calculated from the MNDO potential
energy surface. Hydrogen tunnelling is apparently implicated in the CH4+
CF3 reaction.
Model Calculations of Isotope Effects. IV. Transition State Structures and the Question of Tunnelling in Proton Transfer Reactions
Authors: McLennan DJ
Published: September 2010

Model calculations of primary hydrogen isotope effects in proton transfer reactions are reported.
The geometries and force fields of transition state models have been systematically varied with respect
to both reactant-like and product-like character and to tight against loose character. The models
include both hypothetical cut-off molecules and 2-nitropropane. Values of kH/kD greater than 17 are
calculated for loose, symmetrical transition states in which the sum of the bond orders pertaining to
the transferring proton is set at 0.6, and higher than normal values of (ED-EH) and ADIAH are also
associated with such transition states. It is suggested that transition state looseness is a consequence
of repulsive donor-acceptor steric interactions, and that several sets of experimental results which
have hitherto been rationalized by the invocation of proton tunnelling may equally well be explained
by postulating loose transition states.
Nitrones and Oxaziridines. XXVII. Reaction of C-Cyanooxaziridines with Iron(II) Sulfate: A New Route to Pyrrolidin-2-ones and 3-Pyrrolin-2-ones
Authors: Black DSC , Blackman NA
Published: September 2010

Iron(II) sulfate converts
cyanooxaziridines, derived either from 2-cyano-1-pyrroline 1-oxides or from
5-cyano-2H-pyrrole 1-oxides, into
pyrrolidin-2-ones or 2-pyrrolin-2-ones respectively.
Alkaloids of Agastachys odorata
Authors: Bick IRC , Gillard JW , Leow HM , Preston NW
Published: September 2010

The Tasmanian endemic
proteaceous plant Agastachys odorata
contains the known alkaloid (-)-6β-acetoxy-3α-tigloyloxytropane,
and 3α-(p-hydroxybenzoyloxy)trop-6-ene,
the first naturally occurring tropene base.
Single-Photon Decay Spectroscopy. II. The Pile-up Problem
Authors: Harris CM , Selinger BK
Published: September 2010

When Rutherford and Geiger
tested the independence of simultaneous α particle emissions their results
showed only general agreement with expectation. The main failure in retrospect
appears to be the neglect of dead time, the processing time of the ocular system
for counting flashes, which we find from their results to be about 0.5 s. This
paper deals with pile-up in photon counting and related fields. We deal with
multichannel scaling and the measurement of time-dependent fluorescence
processes for sources of various characteristics. Both mathematical and
electronic methods of dealing with the problem are discussed.
Rates of Formation and Decay of Radical Species During Reaction of Titanium(III) and Hydrogen Peroxide
Authors: Irvine MJ , Wilson IR
Published: September 2010

The kinetics of formation
and decay of the radical species are examined, mainly for solutions in aqueous
hydrochloric acid.
Theoretical Study of the H-+CH3Cl SN2 Reaction
Authors: Talaty ER , Woods JJ , Simons G
Published: September 2010

A theoretical study of the
C3v reaction path of the
H- + CH3Cl → CH4+Cl-
SN2 reaction
with the use of the GAUSSIAN 70 program reveals an earlier departure of the
leaving group than in other ab initio studies of similar reactions involving poorer
leaving groups, and predicts an intermediate planar structure that is highly
ionic and which should be represented as a tight ion triplet, H-[CH3+]Cl-.
1H N.M.R. Studies of Protonation in Pyridazin-3 (2H)-one and 6-Hydroxypyridazin-3 (2H)-one
Authors: Barlin GB , Fenn MD
Published: September 2010

A 1H N.M.R.
study of protonation in pyridazin-3-ol and
pyridazine-3,6-diol revealed that the processes were not simple and suggests
that a mobile tautomeric equilibrium may be involved also.
Acyl Sphingoids and Related Oxazolines
Authors: George EE , Polya JB
Published: September 2010

Oxazolines prepared from sphingoids
or analogues and imidic esters were obtained as
mixtures in which the isomer with heterocyclic oxygen derived from O1
of the parent sphingoid predominated in the case of
erythro sphingoids, and that with original O3
in the case of threo
sphingoids. The separated dry oxazolines
were stable at 0� but isomerized in alcohol, ether or chloroform solution.Hydrolysis of the oxazolines in acid gave the salts of the expected O-acyl compounds or the free O-acyl compounds at pH 5-6, while N-acyl compounds were formed at pH 8;
these transformations occurred without change of configuration except for some
inversion of oxazolines containing the original O3
of erythro sphingenine. O-Acyl compounds changed into N-acyl
isomers in neutral or alkaline media, but the conversion of N-acyl compounds into O-acyl isomers occurred in traces only.
Oxazolines could not be detected as intermediates in the transacylation of O-
or N-acyl sphingoids.� Changes of aged ceramide solutions are
ascribed to photooxidation rather than transacylation.
Chemistry of the Group 1B Elements. XIII. Complexes of Copper(I) or Silver(I) Containing Only Poly(pyrazolyl)borate Ligands
Authors: Bruce MI , Walsh JD
Published: September 2010

The preparation and
properties of the complexes [ML]n [M = Cu or Ag; L = H2B(pz)2, Ph2B(pz)2,
HB(pz)3, HB(Me2pz)3
or B(pz)4] are described.
Kinetic studies on the substitution reactions of (Pyridine-2-carbaldehyde 2'-pyridylhydrazone)nickel(II). A study of stacking interactions in outer-sphere complexes
Authors: Renfrew RW , Osvath P , Weatherburn DC
Published: September 2010

Kinetics of the formation
reactions of the mono and bis complexes of
pyridine-2-carbaldehyde 2'-pyridylhydrazone (paphy)
with nickel((II), the mono complex of 6-methylpyridine-2-carbaldehyde2'-pyridylhydrazone
(mpaphy) with nickel(II), and of the ternary complexes
of Ni(paphy)2+ with terpy, bpy, phen and pada
and Ni(paphy)2+ and Ni(phen)2+
with mpaphy have been studied inaqueous
solution at 25°C and ionic strength 0.1 mol dm-3 (NaNO3).
The rates of the formationreactions of the mono
complexes are slower than expected on the basis of the usual water-loss mechanism, and ring closure probably contributes to the
observed rates. The formation of the bisand ternary
complexes is usually more rapid than predicted by the water-loss mechanism. The
enhanced rates are attributed to large outer-sphere association constants due
to 'stacking' interactions between the incoming and bound ligands.
Pyrimidine N-oxides, III. The oxidation of 5-nitrosopyrimidine-4,6-diamine
Authors: Cowden WB , Jacobson NW
Published: September 2010

The oxidation of
5-nitrosopyrimidine-4,6-diamine by hydrogen peroxide in trifluoroacetic acid
has been reexamined and the products shown to be 4,6-diamino-5-nitropyrimidin-2-ol,
5-nitropyrimidine-4,6-diamine and 5-nitropyrimidine-4,6-diamine 1,3-dioxide.
Quinones and quinone methides. VI. Reactions of 2-Arylmethyl- and 2-(1-Arylethyl)- 1,4-benzoquinones with 4-hydroxy-2H-1-benzopyran-2-one
Authors: Jurd L , Wong RY
Published: September 2010

In alcoholic potassium
hydroxide 2-methoxy-5-(4-methoxyphenylmethyl)- 1,4-benzoquinone (I) reacts with
4-hydroxy-2H-1-benzopyran-2-one (7) to yield the quinol (8a). In pyridine,
however,(1) tautomerizes to the ortho-quinone methide which combines with (7) to
yield (17a). 2-(1- Arylethyl-1,4-benzoquinones yield quinols related to (8a) in
both alcoholic potassium hydroxide and pyridine solutions; this indicates that
quinones methides which might be formed from these quinones are relatively
unreactive to nucleophiles.
Chemistry of the Podocarpaceae. LV. Conversion of 8α, 13-Epoxylabd-14-en-2-one into 3β-Hydroxy-13, 14, 15, 16-tetranorlabd-8(17)-en-12-oic acid
Authors: Cambie RC , Leong SH , Palmer BD , Preston AF
Published: September 2010

8α,13-Epoxylabd-14-en-2-one
(2-oxomanoyl oxide) (1) has been converted into 3β-hydroxy-13,14,15,16-tetranorlabd-8(17)-en-12-oic
acid (7), a compound with potential as an optically active intermediate for
synthesis. Attempts to couple the acid (7) electrolytically to form α-onocerin
are reported. Coupling of 2-methylenecyclohexylacetic acid (40) gives the dimer
1,2-bis(2-methyl-enecyclohexyl)ethane (43) in 45% yield.
The influence of oxygen pressure on lead oxidation kinetics
Authors: Hope GA
Published: September 2010

The dependence of the
oxidation rate of lead films on the pressure of oxygen was investigated by
ellipsometric and resistance techniques for oxygen pressures between 200 Pa and
100 kPa and in the temperature range 323-423 K.
Measurements of the pressure dependence were obtained by studying the change in
oxidation rate following an abrupt change in pressure. The results of all
experiments indicated a small positive dependence, though significant
variations in the values were observed both with extent of oxidation, and
between experiments conducted at different temperatures. During the first few
minutes of the reaction an unusual trend was noted in the observed kinetics
which could be interpreted as being due to absorption of oxygen, by the metal
close to the metal-oxide interface, resulting in changes to the metal
conductivity and the refractive index, determined by ellipsometry,
of the lead substrate.
The chemistry of pyrrolic compounds. XLIV. The preparation and comparative spectroscopic study of some isomeric diformyldeuteroporphyrins
Authors: Clezy PS , Fookes CJR
Published: September 2010

A comparative study of the
electronic and 1H n.m.r. spectra of five isomeric diformyldeuteroporphyrins has been carried out. Clear
distinctions can be recognized in the electronic spectra of the diformyldeuteroporphyrins, depending on the relative
positions of the two formyl groups. Since many different substituents can be
converted into the formyl group, it is suggested that this correlation between
substituent distribution and spectroscopic pattern may be employed as an aid in
problems of structure determination. As an illustration, the method has been
used to elucidate the structure of an acrylate by- product formed during the
synthesis of intermediates leading to the protoporphyrins
having vinyl groups in opposite pyrrolic ring systems.
The synthesis of 2-(5-Phenylthiazol-4-y1)benzoic acids
Authors: Teitei T
Published: September 2010

The four-step synthesis of
2-(5-phenylthiazol-4-yl)benzoic acid (2a), and its 2-amino derivatives (2b),
required for testing as potential plant growth regulators, is described. The
α-bromo ketone (9b)
was conveniently prepared from commercially available 3- benzylidenephthalide
(8) in two steps, and in turn formed the thiazole esters (12) on treatment with
either a mixture of formamide and phosphorus pentasulfide
or thiourea. Hydrolysis of the esters (12) furnished
the above benzoic acids.
An improved method for the synthesis of 2,2-disubstituted and 2-monosubstituted 1,3-benzodioxoles
Authors: Cole ER , Crank G , Minh HTH
Published: September 2010

The reactions of catechol with ketones and aldehydes
have been studied and convenient procedures have been developed for the
preparation of the title compounds in high yields. These products undergo
virtually quantitative nitration at position 5, thus providing a source of
derivatives substituted in the benzene ring.
Orbital interactions. VIII. Competition kinetic measurements of the Birch reduction of some compounds having the bicyclo[2,2,1]heptadiene framework as a means of investigating orbital interactions through space in these systems
Authors: Paddon-Row MN , Hartcher R
Published: September 2010

Relative rate constants for
the Birch reduction (Li/liq. NH3/t-butyl
alcohol) of norbornadiene (1),1,4-dihydro-1,4-methanonaphthalene
(3), 9-(1-methylethylidene)-1,4-dihydro-1,4-methanonaphthalene(5), 1,4- dihydro-1,4-epoxynaphthalene
(7), lithium benzoate, α-methylstyrene, and the hexahydrobenzenomethanoanthracene(20a), were obtained and
compared with that obtained for the reduction of norbornene from an earlier
study. Compounds (1), (3) and (5) were some 105 times
more readily reduced than norbornene. These results are best explained in terms
of the presence of through-space interactions operating between the two lowest
unoccupied molecular orbitals in these molecules. The Birch reduction of (7)
gave mainly 1,4-dihydronaphthalene (17).A mechanism for this reaction is
presented.
Chemistry of the Group 1B metals. XIV. Some poly(pyrazolyl)borate derivatives containing gold
Authors: Borkett NF , Bruce MI , Walsh JD
Published: September 2010

Reactions of
poly(pyrazolyl)borate anions with HAuCl4 have given the complexes
AuCl2[(pz)2BPh2],
AuCl2[(pz)3BH], AuCl2[(Me2pz)3BH]
and AuCl2[(pz)4B] (pz = pyrazolyl, C3H3N2; Me2pz
= 3,5-dimethylpyrazolyl); AuCl2[(Me2pz)3BH]
decomposes rather easily to form [AuCl2(Me2pz)]3,
while Au(pz)[P(OMe)3]
was obtained from a reaction between AuCl2[(pz)4B]
and P(OMe)3.
Crystal structure of trans-Amminebis(ethane-1,2-diamine)sulfitocobalt(III) perchlorate
Authors: Raston CL , White AH , Yandell JK
Published: September 2010

The crystal structure of
the title compound, trans- [Co(C2N2H8)2(NH3)(SO3)]
ClO4, has been determined by single-crystal X-ray diffraction
methods at 295(1)K and refined by least squares to a residual of 0.061 for 2989
'observed' reflections. Crystals are monoclinic, P21/n, a 6.863(3),
b 14.713(6), c 13.279(8) Ǻ, β 104.45(4)°, Z 4. Whereas the Co-S bond
has the common value of 2.227(2) Ǻ, Co-N is remarkably long, being
2.070(3) Ǻ, this being ascribed to a structural trans effect.
Some metal-ion complexes with ligands formed by reactions of amines with aliphatic carbonyl compounds. VIII. Some copper(II) β-Imino alcohol and β-Imino-olato compounds
Authors: Martin JWL , Curtis NF
Published: September 2010

Compounds of copper(II)
with chelated β-imino alcohols are formed by
reaction of 4-hydroxy-4-methylpentan-2-one, hmp, with
copper(II) compounds of ethane-1,2-diamine, 2-methylpropane-1,2-diamine,
meso-1,2- diphenylethane-1,2-diamine, 2-(pyridin-2-yl)ethanamine, 3-azapentane-
1,5-diamine and 4-azaheptane-1,7-diamine. A dinuclear, spin-coupled di- μ-olato bridged derivative of a β-imino
alkoxide, formed by reaction of hmp with 2-(pyridin-2-yl)ethanaminecopper(II),
has a spin-coupling constant J of -286 cm-1, based on magnetic
susceptibility data over the 100-300 K temperature range. A related compound
formed by N,N- diethylethane-1,2-diamine, which could have an analogous
structure containing water, or an isomeric structure with the β-imino
alcohol and with di-μ-hydroxide bridging, has a
J value of about -130 cm-1, similarly determined. The preparation of
a copper(11) compound with the tetradentate ligand
4,6-trimethyl-1,9-bis(pyridin-2-yl)-3,7-diazanon-3- ene,
by reaction of bis[2-(pyridin-2-yl)ethanamine]copper(II) perchlorate with
acetone, is reported.
Compounds of cobalt(II), nickel(II) and copper(II) with 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene
Authors: Martin JWL , Curtis NF
Published: September 2010

Compounds of the macrocycle
2,4,4,9-tetramethyl-1,5,9-triazacyclododec- 1-ene (dla)
with cobalt(II), nickel(II) and copper(II) are formed by reaction with acetone
of complexes of these ions with 4-methyl-4- azaheptane-1,7-diamine. The
preparations of M(dla)(NCS)2, (M = CoII, NiII
and CuII), [M(dla)-(en)]
(ClO4)2, [{M(dla)(OH)}2]
(ClO4)2, [{M(dla)}2CO3]
(ClO4]2, [M(dla)(acac)] ClO4, [{M(dla)}2-
C2O4] (ClO4)2 (M = NiII, CuII),
and [{Ni(dla)Cl}2](ClO4)2
are reported. The compounds are all assigned five-coordinate structures. The
compounds [{M(dla)}2CO3] (ClO4)2,
[{Cu(dla)(OH)}2]-(ClO4)2
and [{Cu(dla)}2C2O4](ClO4)2
show appreciable antiferromagnetic spin-coupling.
The reactivity of p-nitrophenyl esters with surfactants in nonaqueous solvents. IV. p-Nitrophenyl acetate in benzene solutions of dodecylammonium phenoxides
Authors: O'Conner CJ , Ramage RE
Published: September 2010

The rate of decomposition
of p-nitrophenyl acetate, pnpa, has been measured at
298 K in benzene solutions of a series of dodecylammonium 4-substituted
phenoxide salts, CH3(CH2)11NH3+
-OC6H4X-p (where X = H, Cl, Br,
Me or MeO). Absorbance measurements indicate that
aggregation of these compounds occurs at concentrations greater than 10-4
mol dm-3 in benzene. The observed rate constants of aminolysis are
affected by the basicity of the phenol. In the presence of solubilized water
the rate of decomposition of pnpa is increased
slightly due to an increase in the effective concentration of the free amine
and due to the occurrence of hydrolysis. The effect of an increase in
temperature and of a change in solvent (to toluene) has been studied.
Chromatographic separations of diastereoisomers of the 5,7,12,14-tetramethyl-1,4,8,11 -tetraazacyclotetradeca-4,11-dienenickel(II) cation, and characterization of the nickel(II) complex of the new macrocyclic ligand 5,7,7,12,14-pentamethyl- 1,4,8,11 -tetraazacyclotetradeca-4,11-diene
Authors: Searle GH , Hay RW , Jeragh B
Published: September 2010

Planar nickel(II) complexes
of different macrocyclic tetraazacyclotetradeca-4,11-diene ligands and
diastereoisomers which differ in chiral carbon configurations have been
separated by cation- exchange chromatography on SP-Sephadex C-25 resin. Of the
limited number of successful eluents, sodium glycinate is the most effective.
The separations are considered to result from differential associations between
the glycinate anion and the complex cations. The technique has been
successfully applied to the separation of the C-racemic and C-meso
diastereoisomers of [Ni(ttcd)]2+ (ttcd = 5,7,12,14-tetramethyl-1,4,8,11-
tetraazacyclotetradeca-4,11-diene). Diastereoisomers arising from chiral NH
centres cannot be separated by this technique since the effective eluents are
generally basic, causing epimerization. The use of 1H and 13C
n.m.r. spectra in these studies is discussed, and the isolation of the
nickel(II) complex of the new macrocyclic ligand ptcd
(5,7,7,12,14-pentamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) by column
chromatography described. The isolated [Ni(ptcd)]-(ClO4)2
is a mixture of the diastereoisomers C-axial,N-racemic and C-axial,N-meso.