# New Quasi-One-Dimensional Organic-Inorganic Hybrid Material: 1,3-Bis(4-piperidinium)propane Pentachlorobismuthate(III) Synthesis, Crystal Structure, and Spectroscopic Studies

Authors: Hela Ferjani; Habib Boughzala
Journal: Journal of Materials
 (2014)

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## Abstract

The organic-inorganic hybrid compound (C13H28N2) BiCl5 was synthesized by solvothermal method. The crystal structure was solved by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic system space group Cmc21 with a=15.826(4) Å, b=18.746(6) Å, c=7.470(3) Å, and Z=4. The crystal structure was refined down to R=0.019. It consists of corrugated layers of [BiCl5]2− chains, separated by organic [H2TMDP]2+ cations (TMDP=1,3-Bis(4-piperidyl)propane = C13H26N2). The crystal cohesion is achieved by hydrogen bonds N–H⋯Cl joining the organic and inorganic layers. The influence of the organic cations' flexibility is discussed. Raman and infrared spectra of the title compound were recorded in the range of 50–400 and 400–4000 cm−1, respectively. Semiempirical parameter model three (PM3) method has been performed to derive the calculated IR spectrum. The crystal shape morphology was simulated using the  Bravais-Friedel and Donnay-Harker model.


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## Body

## 1. Introduction

Halobismuthates organic-inorganic hybrids are interesting systems because of the opportunity to combine the organic and the inorganic materials’ proprieties. Nowadays, these compounds are the subject of intense investigations in many fields like optoelectronics and semiconducting [1–4]. The anionic sublattices of these materials are often built up by distorted [BiX6]3− octahedra (X=halogen). These octahedra can be isolated or linked by corners, edges, or faces leading to low dimensional inorganic framework. It is still a great challenge to control the structure dimensionalities of metal-halide anionic frameworks. In fact, the structural type depends on the experimental conditions, such as the solvent, ratio of reagents, and temperature. The organic cation size, charge, steric encumbrance, and the conformation can have a decisive influence. The organic moiety can be used as physical and electronic barrier, contributing to original electrical and optical behavior [5–8]. In these materials the crystal packing is directed by the interactions between the components constituting the solid such as hydrogen bonding, Van Der Waals, and electrostatic interactions.In this work we present the results of the structural and spectroscopic studies on a new pentachlorobismuthate-based hybrid compound. Semiempirical parameter model three (PM3) computations are used in order to perform the vibrational analysis of the studied structure.


## 2. Materials and Methods

### 2.1. Synthesis

In a 23 mL teflon autoclave, a mixture of bismuth chloride BiCl3 and 1,3-bis(4-pyridyl) propane (TMDP) in molar ratio 1 : 2 was dissolved in 10 mL of absolute ethanol. The autoclave was heated to 140°C for three days. Colorless crystals were isolated from the mixture after cooling to room temperature. A suitable single crystal was selected for the structural determination.


### 2.2. X-Ray Data Collection

The data was collected using an Enraf-Nonious CAD-4 X-Ray diffractometer [10] at 298 K equipped with graphite monochromator and MoKα radiation (λ=0.71073Å) using the ω/2θ scan mode. An empirical psi-scan [11] absorption correction was applied. The structure was refined by Full-matrix least-squares based on F2 using SHELXL-97 [12]. All nonhydrogen atoms were directly located from difference Fourier maps and refined with anisotropic displacement parameters. Hydrogen atoms were located at their idealized positions using appropriate HFIX instructions in SHELXL-97 [12] and included in subsequent least-squares refinement cycles in riding-motion approximation. Molecular graphics were prepared using Diamond 3 [13]. CCDC-800676 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge at http://www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre (CCDC), 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44(0)1223-336033; email: deposit@ccdc.cam.ac.uk. Crystal data and parameters of the final refinement are reported in Table 1.Table 1
Crystal data and structure refinement details for (H2TMDP)BiCl5.
Crystal data
Empirical formula
C13H28N2·BiCl5
Formula weight (g/mol)
598.60
Crystal system, space group
Orthorhombic, Cmc21
a (Å)
15.826(4)
b (Å)
18.746(6)
c (Å)
7.470(3)
V (Å3)
2216.2(13)
Z
4
µ (mm−1)
8.56
Dx (Mg m−3)
1.794
F(000)
1152
Crystal size (mm)
0.56
×
0.31
×
0.24
Crystal habit
Colorless Prism
Data collection
Diffractometer
Enraf Nonius CAD4
Monochromater
Graphite
Radiation type,λ (Å)
Mo Kα, 0.71073
T (K)
298
Indexes range
-
1
≤
h
≤
20; -23≤k≤3; -1≤l≤9
Absorption correction:
psi-scan
Tmin⁡/Tmax⁡
0.675/0.999
Measured reflections
1944
Independent reflections
1541
Observed refl. withI>2σ(I)
1476
Rint⁡
0.014
Refinement
Refinement on
F
2
Data/restraints/parameters
1476/1/104
R[F2>2σ(F2)]
0.019
wR(F2)
0.046
GoF = S
1.10
Δρmax⁡/Δρmin⁡ (e·Å−3)
0.73/−1.02
CCDC deposit number
800676


### 2.3. Physicochemical Characterization Techniques

Room temperature infrared absorption spectrum was recorded in 400–4000 cm−1 frequency range on a Perkin Elmer Paragon 1000 Pc spectrometer by dispersing 2% of the studied compound in KBr discs. Raman scattering was excited by 488 nm wavelength and recorded at room temperature using a JOKIN-YVON (T64000) spectrometer. Optical absorption spectrum of the(C13H28N2) BiCl5 pellets was measured at room temperature using a UV-Visible absorption spectrometer Perkin Elmer Lambda 45. The X-ray powder diffraction measurement was performed on a D8 ADVANCE BRUKER diffractometer using Cu Kα1/α2 radiations and equipped with Lynxeye accelerator.


## 2.1. Synthesis

In a 23 mL teflon autoclave, a mixture of bismuth chloride BiCl3 and 1,3-bis(4-pyridyl) propane (TMDP) in molar ratio 1 : 2 was dissolved in 10 mL of absolute ethanol. The autoclave was heated to 140°C for three days. Colorless crystals were isolated from the mixture after cooling to room temperature. A suitable single crystal was selected for the structural determination.


## 2.2. X-Ray Data Collection

The data was collected using an Enraf-Nonious CAD-4 X-Ray diffractometer [10] at 298 K equipped with graphite monochromator and MoKα radiation (λ=0.71073Å) using the ω/2θ scan mode. An empirical psi-scan [11] absorption correction was applied. The structure was refined by Full-matrix least-squares based on F2 using SHELXL-97 [12]. All nonhydrogen atoms were directly located from difference Fourier maps and refined with anisotropic displacement parameters. Hydrogen atoms were located at their idealized positions using appropriate HFIX instructions in SHELXL-97 [12] and included in subsequent least-squares refinement cycles in riding-motion approximation. Molecular graphics were prepared using Diamond 3 [13]. CCDC-800676 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge at http://www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre (CCDC), 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44(0)1223-336033; email: deposit@ccdc.cam.ac.uk. Crystal data and parameters of the final refinement are reported in Table 1.Table 1
Crystal data and structure refinement details for (H2TMDP)BiCl5.
Crystal data
Empirical formula
C13H28N2·BiCl5
Formula weight (g/mol)
598.60
Crystal system, space group
Orthorhombic, Cmc21
a (Å)
15.826(4)
b (Å)
18.746(6)
c (Å)
7.470(3)
V (Å3)
2216.2(13)
Z
4
µ (mm−1)
8.56
Dx (Mg m−3)
1.794
F(000)
1152
Crystal size (mm)
0.56
×
0.31
×
0.24
Crystal habit
Colorless Prism
Data collection
Diffractometer
Enraf Nonius CAD4
Monochromater
Graphite
Radiation type,λ (Å)
Mo Kα, 0.71073
T (K)
298
Indexes range
-
1
≤
h
≤
20; -23≤k≤3; -1≤l≤9
Absorption correction:
psi-scan
Tmin⁡/Tmax⁡
0.675/0.999
Measured reflections
1944
Independent reflections
1541
Observed refl. withI>2σ(I)
1476
Rint⁡
0.014
Refinement
Refinement on
F
2
Data/restraints/parameters
1476/1/104
R[F2>2σ(F2)]
0.019
wR(F2)
0.046
GoF = S
1.10
Δρmax⁡/Δρmin⁡ (e·Å−3)
0.73/−1.02
CCDC deposit number
800676


## 2.3. Physicochemical Characterization Techniques

Room temperature infrared absorption spectrum was recorded in 400–4000 cm−1 frequency range on a Perkin Elmer Paragon 1000 Pc spectrometer by dispersing 2% of the studied compound in KBr discs. Raman scattering was excited by 488 nm wavelength and recorded at room temperature using a JOKIN-YVON (T64000) spectrometer. Optical absorption spectrum of the(C13H28N2) BiCl5 pellets was measured at room temperature using a UV-Visible absorption spectrometer Perkin Elmer Lambda 45. The X-ray powder diffraction measurement was performed on a D8 ADVANCE BRUKER diffractometer using Cu Kα1/α2 radiations and equipped with Lynxeye accelerator.


## 3. Results and Discussion

### 3.1. X-Ray Diffraction Characterization

The X-ray powder diffraction measurement was carried out to check the title compound purity using the raw X-ray powder diffraction and the structural investigation results. As shown in Figure1, the similarity of the calculated pattern and the observed one confirms the high purity level of the synthesised phase.Figure 1
Observed (red line) and calculated (blue line) powder X-ray diffraction patterns of (H2TMDP)BiCl5.


### 3.2. Structure Description and Comparison

The asymmetric part of the unit cell consists of a half (H2TMDP)2+ cation, one Bi(III) cation, and four Cl- anions as shown in Figure 2. The inorganic secondary building unit consists of a cis corner-sharing BiCl6 distorted octahedra running along the (001) crystallographic direction (Figure 3). The zigzag anionic chains have been observed in several other halobismuthate materials [14, 15]. The shortest Bi–Bi distance characterizing the chain period (Figure 4) has been found to be the significant structural parameter, determining the volume of the cavities occupied by (H2TMDP)2+ cations.Figure 2
The asymmetric unit part of the (H2TMDP)BiCl5 compound showing the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. The superscripts (i) and (ii) indicate the symmetry positions (-x,y,z) and (-x,-y,-1/2+z).Figure 3
View of the structure of (H2TMDP)BiCl5 along the c axis showing the zigzag chains of the BiCl6 octahedra and the cations.Figure 4
Anionic chain and the Bi–Bi distance in (H2TMDP)BiCl5crystal.Therefore, these cations are stacked between the inorganic sheets, forming zigzag chains (Figure3), and linked to them by weak intermolecular hydrogen bonds N–H⋯Cl via terminal nitrogen atoms; N1–H0A⋯Cl3 = 3.35 Å and N1–H0B⋯Cl1 = 3.34 Å (Figure 5(a)). These flexible bidentate cations adopt the anti-anti (TT) conformation, which is the most stable among others [16]. The shortest N–H⋯Cl hydrogen bond geometries are presented in Table 3. The resulting 1D chains of cations and those of anions are packed tightly in alternating mode to form a 3D network (Figure 3). The Cl–Bi–Cl angles vary from 84.77(5)° to 95.49(1)° for cis and 169.52(1)° to 173.70(7)° for trans arrangements (Table 2). The longest Bi–Cl bond lengths fall in the range 2.533(3) Å–3.046(2) Å for the bivalent bridging chlorine. On the other hand, the shortest ones are for the monovalent anions pointing to the organic cationic space (Figure 4). It is worth noting that the H2TMDP is a flexible cation and endowed with many conformations. This flexibility presents an important effect in the formation of the inorganic chains leading to multiple structures [17].Table 2
Selected bond distances (Å) and angles (°) for (H2TMDP)BiCl5.
Bond distances (Å)
Bi–Cl1i
2.6936(14)
C1–C2
1.498(8)
Bi–Cl1
2.6936(14)
C2–C3
1.522(7)
Bi–Cl2
2.533(3)
C3–C4
1.533(9)
Bi–Cl3
2.665(3)
C4–C5
1.520(8)
Bi–Cl4
2.769(3)
C3–C6
1.519(9)
Bi–Cl4ii
3.046(2)
C6–C7
1.580(14)
N–C1
1.497(7)
C3–C4
1.533(9)
N–C5
1.498(7)
Angles (°)
Cl2–Bi–Cl3
95.49(10)
C6–C3–C2
110.7(7)
Cl2–Bi–Cl1
84.77(5)
C6–C3–C4
113.6(8)
Cl3–Bi–Cl1
90.13(7)
C2–C3–C4
109.1(6)
Cl1i–Bi–Cl1
169.52(10)
C5–C4–C3
113.4(6)
Cl2–Bi–Cl4
90.81(9)
N–C5–C4
109.3(6)
Cl3–Bi–Cl4
173.70(7)
N–C1–C2
109.4(5)
Cl1–Bi–Cl4
90.45(6)
C1–C2–C3
113.1(6)
Cl2–Bi–Cl4ii
172.17(8)
C3–C6–C7
111.4(9)
Cl3–Bi–Cl4ii
92.34(8)
C6i–C7–C6
105.8(13)
Cl1–Bi–Cl4ii
95.23(5)
Cl4–Bi–Cl4ii
81.36(3)
Bi–Cl4–Biiii
165.87(10)
C1–N–C5
112.8(5)
Symmetry codes:i-x, y, z; ii-x, -y, z-1/2; iii-x, -y, z+1/2.Table 3
Hydrogen bonds and angles for (H2TMDP)BiCl5 (Å, °).
D–H⋯A
D–H
H⋯A
D⋯A
D–H⋯A
N1–H0A⋯Cl3iv
0.9
2.48
3.357
165
N1–H0B⋯Cl1v
0.9
2.45
3.340
169
Symmetry codes:ivx, y, z+1; v-x, y, z+1.A view showing the N–H⋯Cl (green) interactions in the crystal of (H2TMDP)BiCl5(a) N–H⋯Br (blue) and N–H⋯I (red) in (H2TMDP)BiBr4.01I0.99(b) (Hydrogen bonds shown as dashed lines).
(a)
(b)Goforth et al. [9] synthesized a new compound containing a polymeric mixed haloanion (H2TMDP) BiBr4.01I0.99 and presenting similarities with the title compound. Before making any structural comparison, it is necessary to standardize the networks of the two structures (see Table 4). The presence of two halogen (Br, I) larger size than the chlorine increases the cell volume of about 68 Å3. In spite of the inorganic part arrangement similarities the (H2TMDP) BiBr4.01I0.99 structure exhibits a different organic part organization. In fact, in the title structure the cations penetrate into the anionic chains cavities while in the homologous compound they are located just between these chains (Figure 6).Table 4
The crystallographic parameters of (H2TMDP)BiBr4.01I0.99 and (H2TMDP)BiCl5.
Compound
(H2TMDP)BiBr4.01I0.99
(H2TMDP)BiBr4.01I0.99 [9]
(H2TMDP)BiCl5*
Space group
P 212121
P 212121
Cmc21
Crystal system
Orthorhombic
Orthorhombic
Orthorhombic
a (Å)
8.5189(5)
A
=
14.8988
(
9
)
a
=
1
5.826
(
4
)
b (Å)
14.8988(9)
B
=
17.9984
(
11
)
b
=
18.746
(
6
)
c (Å)
17.9984(11)
C
=
8.5189
(
5
)
c
=
7.470
(
3
)
V (Å3)
2284.4(2)
2284.4
(
2
)
2216.2
(
2
)
Z
4
4
4
Cation conformation
TG
TG
TT
*This work.(001) views of the crystal packing in (H2TMDP)BiCl5 (a) and (H2TMDP)BiBr5-xIx (b) [9].
(a)
(b)The organic cations conformation is probably the main differentiating feature between the two structures. Indeed, in our case (H2TMDP) presents a TT conformation (the N–N distance in the a direction is equal to 10.643 Å), whereas in the homologous compound it adopts a TG conformation with a shorter N–N distance (8.645 Å) (see Figures 5(a) and 5(b)). This induces a closeness between the nearest inorganic layers lodging the organic cations and reducing the parameter a of about 6% (a=15.826(4)A=14.899(9) Å).In addition, these cations are propagated in zigzag chains perpendicular tob axis in the hollow cavities of the anionic chain (in our case) and leaves empty channels (Figure 6(a)) between the organic-inorganic chains, whereas in the homologous compound cations occupy the whole of the empty space between the anionic chains, leading to an elongation of parameter b from B=17.9984(11)b=18.746(6) Å (4%).The observed distortion in the (H2TMDP) BiBr4.01I0.99 octahedra compared to those of the title compound is probably due to the replacement of chloride anions by mixed halogens (Br/I). Indeed, the distance Bi–Brbridging = 3.1258(8) Å [9] is slightly longer than Bi–Clbridging = 3.046(2) Å. In addition, the ammonium group located between the cavities is linked by two hydrogen bonds to the main inorganic framework vertices (N–H0A⋯Cl3, 3.357(6) Å, N–H0B⋯Cl1, 3.340(7) Å). The hydrogen bonds network gets closer to the octahedra chains and decreases the c parameter from 8.5189(5) Å to 7.470(3) Å (12%).


### 3.3. Crystal Morphology

Crystal morphology is a key element in many industrial processes and has an enormous impact in the materials processing stages. Thus, rationalization of the relationships between crystal morphology and the arrangement of atoms in the bulk crystal lattice is of great interest in many areas of science. In this way, we wanted to provide a comprehensive understanding of the crystal structure-morphology relationships in this material.The crystal morphology of the title compound was predicted using the Bravais-Fridel, Donnay-Harker model (BFDH) [18–20] (Figure 7(a)). It uses the crystal lattice and symmetry to generate a list of possible growth faces and their relative growth rates. It allows understanding the crystal growth process. The prediction possessed a needle habit with the most developed ({110},{110},{1-10},{-1-10}) faces. New additional small faces ({020},{0-20}) that do not appear in the observed habit (Figure 7(b)) are also predicted. These calculations allow identifying the physical axes and the crystallographic ones.Growth shape from BFDH rules (a), images of the growth morphologies taken with the optical microscope (b) of (H2TMDP)BiCl5.
(a)
(b)


### 3.4. Vibrational Study

To gain information on the crystal structure, we have carried out a vibrational study using infrared absorption and Raman scattering. The infrared and Raman spectra recorded at room temperature are shown in Figures8(a) and 9, respectively. We have calculated the vibrational spectrum (Figure 8(b)) by using semiempirical PM3 geometry optimization by “CAChe” program [21]. The frequencies of the observed and calculated Raman and infrared peaks are reported in Table 5.Table 5
Observed and calculated vibration frequencies (cm−1) of (H2TMDP)BiCl5 and proposed assignments.
Calculatedinfrared
ObservedFT-Raman
FT-IR
Assignments
—
100
—
Bendingmodes
—
120
—
—
214
—
Bi–Cl (Bridge) stretch
—
240
—
Bi–Cl(external) stretch
—
278
—
—
—
954
δ (C–C)
992
—
1073
ν
s (C–C)
1178
—
1272
ν (C–N)
1368
—
1380
ν
as (C–C)
—
—
1460
δ (CH2)
—
—
1580
δ (NH2)
2489
—
2856
ν
s (C–H)
2899
—
2920
ν
as (C–H)
3029
—
3110
ν
s (NH2)
3428
—
3460
ν
as (NH2)Room temperature IR spectra of (H2TMDP)BiCl5 (a) and PM3 computed IR spectra (b).
(a)
(b)Figure 9
Raman spectra of (H2TMDP)BiCl5recorded at low frequency range.


#### 3.4.1. The Vibration of Piperidinium Cation (H2TMDP)2+

The infrared absorption spectrum of the title compound (H2TMDP) BiCl5 shows corresponding vibration bands of 1,3-bis(4-piperidinium)propane cation. The assignments reported in Table 5 are in agreement with the calculated IR spectrum. These modes are well predicted by the calculation. The shift between the observed wave numbers and the calculated ones is probably due to the approximations used in the computations. However, the groups are assumed to be free whereas actually they are engaged by hydrogen bonds.Heterocyclic compounds containing an N–H group exhibit N–H stretching absorption in the region from 3500 to 3200 cm−1. The stretching vibrations of the N–H group are observed at 3460 and 3110 cm−1. The infrared bands observed at 2980–2850 cm−1 region are assigned CH stretching for piperidine [16, 22]. In the 1,3-bis(4-piperidyl)propane, the stretching of CH modes experimentally are observed at 2920–2856 cm−1 region. The stretching modes of CN are observed around 1180–1100 cm−1 for piperidine [16, 22]. Piperidine ring CC stretching modes are obtained in the range 1350–1073 cm−1 [16, 22]. The C–H stretching absorption of methylene group is centered on 2925 cm−1. The infrared band observed at 2856 cm−1 is assigned to symmetric CH2 for methylene group. The asymmetric stretching mode of methylene group is observed at 2920 cm−1.


#### 3.4.2. The Vibration ofBiCl63-

Based on some studies carried out for previous works and reported on similar compounds containing (BiCl5)2- anions [23, 24], we propose an attempt of assignment of the observed bands. The low Raman frequencies of (H2TMDP) BiCl5 crystal can be assigned to vibrations of BiCl63- octahedral corner sharing. The Bi–Cl stretching modes are observed in the low frequency range between 400 and 100 cm−1. The 278 cm−1 and 240 cm−1 bands are, respectively, assigned to the Bi–Cl external ant-symmetric and symmetric stretching. Raman lines at 214, 120, and 100 cm−1 most likely correspond to the Bi–Cl bridging stretch and the Cl–Bi–Cl deformation.


### 3.5. UV-Visible Spectroscopy

In the UV-Vis absorption the chlorobismuthate(III) anions are characterized by metal centered (MC) sp and Ligand to metal centered transitions (LMCT) at lower wavelengths [25, 26]. In fact, The LMCT may occur only at rather high energies and all long wavelength transitions were assigned to metal-centered transitions [27, 28].The  optical  properties  of  1,3-bis(4-piperidinium)propane  pentachlorobismuthate(III) pellets were assessed by its UV-Vis absorption spectrum shown in Figure10.Figure 10
Diffuse reflectance UV-Visible absorption spectra for (H2TMDP)BiCl5.The (H2TMDP) BiCl5 exhibits two distinct absorptions bands cantered at 287 nm and 410 nm. The highest absorption peak at 410 nm is assigned to the Metal Centered (MC) transition from the 6s to 6s 6p of Bismuth atom. The band at 287 nm can be attributed to Ligand, to metal charge transfer (LMCT) transition from the 5p orbital of Cl to 6p orbital of Bi(III) as described in previous outputs [25–28].


## 3.1. X-Ray Diffraction Characterization

The X-ray powder diffraction measurement was carried out to check the title compound purity using the raw X-ray powder diffraction and the structural investigation results. As shown in Figure1, the similarity of the calculated pattern and the observed one confirms the high purity level of the synthesised phase.Figure 1
Observed (red line) and calculated (blue line) powder X-ray diffraction patterns of (H2TMDP)BiCl5.


## 3.2. Structure Description and Comparison

The asymmetric part of the unit cell consists of a half (H2TMDP)2+ cation, one Bi(III) cation, and four Cl- anions as shown in Figure 2. The inorganic secondary building unit consists of a cis corner-sharing BiCl6 distorted octahedra running along the (001) crystallographic direction (Figure 3). The zigzag anionic chains have been observed in several other halobismuthate materials [14, 15]. The shortest Bi–Bi distance characterizing the chain period (Figure 4) has been found to be the significant structural parameter, determining the volume of the cavities occupied by (H2TMDP)2+ cations.Figure 2
The asymmetric unit part of the (H2TMDP)BiCl5 compound showing the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. The superscripts (i) and (ii) indicate the symmetry positions (-x,y,z) and (-x,-y,-1/2+z).Figure 3
View of the structure of (H2TMDP)BiCl5 along the c axis showing the zigzag chains of the BiCl6 octahedra and the cations.Figure 4
Anionic chain and the Bi–Bi distance in (H2TMDP)BiCl5crystal.Therefore, these cations are stacked between the inorganic sheets, forming zigzag chains (Figure3), and linked to them by weak intermolecular hydrogen bonds N–H⋯Cl via terminal nitrogen atoms; N1–H0A⋯Cl3 = 3.35 Å and N1–H0B⋯Cl1 = 3.34 Å (Figure 5(a)). These flexible bidentate cations adopt the anti-anti (TT) conformation, which is the most stable among others [16]. The shortest N–H⋯Cl hydrogen bond geometries are presented in Table 3. The resulting 1D chains of cations and those of anions are packed tightly in alternating mode to form a 3D network (Figure 3). The Cl–Bi–Cl angles vary from 84.77(5)° to 95.49(1)° for cis and 169.52(1)° to 173.70(7)° for trans arrangements (Table 2). The longest Bi–Cl bond lengths fall in the range 2.533(3) Å–3.046(2) Å for the bivalent bridging chlorine. On the other hand, the shortest ones are for the monovalent anions pointing to the organic cationic space (Figure 4). It is worth noting that the H2TMDP is a flexible cation and endowed with many conformations. This flexibility presents an important effect in the formation of the inorganic chains leading to multiple structures [17].Table 2
Selected bond distances (Å) and angles (°) for (H2TMDP)BiCl5.
Bond distances (Å)
Bi–Cl1i
2.6936(14)
C1–C2
1.498(8)
Bi–Cl1
2.6936(14)
C2–C3
1.522(7)
Bi–Cl2
2.533(3)
C3–C4
1.533(9)
Bi–Cl3
2.665(3)
C4–C5
1.520(8)
Bi–Cl4
2.769(3)
C3–C6
1.519(9)
Bi–Cl4ii
3.046(2)
C6–C7
1.580(14)
N–C1
1.497(7)
C3–C4
1.533(9)
N–C5
1.498(7)
Angles (°)
Cl2–Bi–Cl3
95.49(10)
C6–C3–C2
110.7(7)
Cl2–Bi–Cl1
84.77(5)
C6–C3–C4
113.6(8)
Cl3–Bi–Cl1
90.13(7)
C2–C3–C4
109.1(6)
Cl1i–Bi–Cl1
169.52(10)
C5–C4–C3
113.4(6)
Cl2–Bi–Cl4
90.81(9)
N–C5–C4
109.3(6)
Cl3–Bi–Cl4
173.70(7)
N–C1–C2
109.4(5)
Cl1–Bi–Cl4
90.45(6)
C1–C2–C3
113.1(6)
Cl2–Bi–Cl4ii
172.17(8)
C3–C6–C7
111.4(9)
Cl3–Bi–Cl4ii
92.34(8)
C6i–C7–C6
105.8(13)
Cl1–Bi–Cl4ii
95.23(5)
Cl4–Bi–Cl4ii
81.36(3)
Bi–Cl4–Biiii
165.87(10)
C1–N–C5
112.8(5)
Symmetry codes:i-x, y, z; ii-x, -y, z-1/2; iii-x, -y, z+1/2.Table 3
Hydrogen bonds and angles for (H2TMDP)BiCl5 (Å, °).
D–H⋯A
D–H
H⋯A
D⋯A
D–H⋯A
N1–H0A⋯Cl3iv
0.9
2.48
3.357
165
N1–H0B⋯Cl1v
0.9
2.45
3.340
169
Symmetry codes:ivx, y, z+1; v-x, y, z+1.A view showing the N–H⋯Cl (green) interactions in the crystal of (H2TMDP)BiCl5(a) N–H⋯Br (blue) and N–H⋯I (red) in (H2TMDP)BiBr4.01I0.99(b) (Hydrogen bonds shown as dashed lines).
(a)
(b)Goforth et al. [9] synthesized a new compound containing a polymeric mixed haloanion (H2TMDP) BiBr4.01I0.99 and presenting similarities with the title compound. Before making any structural comparison, it is necessary to standardize the networks of the two structures (see Table 4). The presence of two halogen (Br, I) larger size than the chlorine increases the cell volume of about 68 Å3. In spite of the inorganic part arrangement similarities the (H2TMDP) BiBr4.01I0.99 structure exhibits a different organic part organization. In fact, in the title structure the cations penetrate into the anionic chains cavities while in the homologous compound they are located just between these chains (Figure 6).Table 4
The crystallographic parameters of (H2TMDP)BiBr4.01I0.99 and (H2TMDP)BiCl5.
Compound
(H2TMDP)BiBr4.01I0.99
(H2TMDP)BiBr4.01I0.99 [9]
(H2TMDP)BiCl5*
Space group
P 212121
P 212121
Cmc21
Crystal system
Orthorhombic
Orthorhombic
Orthorhombic
a (Å)
8.5189(5)
A
=
14.8988
(
9
)
a
=
1
5.826
(
4
)
b (Å)
14.8988(9)
B
=
17.9984
(
11
)
b
=
18.746
(
6
)
c (Å)
17.9984(11)
C
=
8.5189
(
5
)
c
=
7.470
(
3
)
V (Å3)
2284.4(2)
2284.4
(
2
)
2216.2
(
2
)
Z
4
4
4
Cation conformation
TG
TG
TT
*This work.(001) views of the crystal packing in (H2TMDP)BiCl5 (a) and (H2TMDP)BiBr5-xIx (b) [9].
(a)
(b)The organic cations conformation is probably the main differentiating feature between the two structures. Indeed, in our case (H2TMDP) presents a TT conformation (the N–N distance in the a direction is equal to 10.643 Å), whereas in the homologous compound it adopts a TG conformation with a shorter N–N distance (8.645 Å) (see Figures 5(a) and 5(b)). This induces a closeness between the nearest inorganic layers lodging the organic cations and reducing the parameter a of about 6% (a=15.826(4)A=14.899(9) Å).In addition, these cations are propagated in zigzag chains perpendicular tob axis in the hollow cavities of the anionic chain (in our case) and leaves empty channels (Figure 6(a)) between the organic-inorganic chains, whereas in the homologous compound cations occupy the whole of the empty space between the anionic chains, leading to an elongation of parameter b from B=17.9984(11)b=18.746(6) Å (4%).The observed distortion in the (H2TMDP) BiBr4.01I0.99 octahedra compared to those of the title compound is probably due to the replacement of chloride anions by mixed halogens (Br/I). Indeed, the distance Bi–Brbridging = 3.1258(8) Å [9] is slightly longer than Bi–Clbridging = 3.046(2) Å. In addition, the ammonium group located between the cavities is linked by two hydrogen bonds to the main inorganic framework vertices (N–H0A⋯Cl3, 3.357(6) Å, N–H0B⋯Cl1, 3.340(7) Å). The hydrogen bonds network gets closer to the octahedra chains and decreases the c parameter from 8.5189(5) Å to 7.470(3) Å (12%).


## 3.3. Crystal Morphology

Crystal morphology is a key element in many industrial processes and has an enormous impact in the materials processing stages. Thus, rationalization of the relationships between crystal morphology and the arrangement of atoms in the bulk crystal lattice is of great interest in many areas of science. In this way, we wanted to provide a comprehensive understanding of the crystal structure-morphology relationships in this material.The crystal morphology of the title compound was predicted using the Bravais-Fridel, Donnay-Harker model (BFDH) [18–20] (Figure 7(a)). It uses the crystal lattice and symmetry to generate a list of possible growth faces and their relative growth rates. It allows understanding the crystal growth process. The prediction possessed a needle habit with the most developed ({110},{110},{1-10},{-1-10}) faces. New additional small faces ({020},{0-20}) that do not appear in the observed habit (Figure 7(b)) are also predicted. These calculations allow identifying the physical axes and the crystallographic ones.Growth shape from BFDH rules (a), images of the growth morphologies taken with the optical microscope (b) of (H2TMDP)BiCl5.
(a)
(b)


## 3.4. Vibrational Study

To gain information on the crystal structure, we have carried out a vibrational study using infrared absorption and Raman scattering. The infrared and Raman spectra recorded at room temperature are shown in Figures8(a) and 9, respectively. We have calculated the vibrational spectrum (Figure 8(b)) by using semiempirical PM3 geometry optimization by “CAChe” program [21]. The frequencies of the observed and calculated Raman and infrared peaks are reported in Table 5.Table 5
Observed and calculated vibration frequencies (cm−1) of (H2TMDP)BiCl5 and proposed assignments.
Calculatedinfrared
ObservedFT-Raman
FT-IR
Assignments
—
100
—
Bendingmodes
—
120
—
—
214
—
Bi–Cl (Bridge) stretch
—
240
—
Bi–Cl(external) stretch
—
278
—
—
—
954
δ (C–C)
992
—
1073
ν
s (C–C)
1178
—
1272
ν (C–N)
1368
—
1380
ν
as (C–C)
—
—
1460
δ (CH2)
—
—
1580
δ (NH2)
2489
—
2856
ν
s (C–H)
2899
—
2920
ν
as (C–H)
3029
—
3110
ν
s (NH2)
3428
—
3460
ν
as (NH2)Room temperature IR spectra of (H2TMDP)BiCl5 (a) and PM3 computed IR spectra (b).
(a)
(b)Figure 9
Raman spectra of (H2TMDP)BiCl5recorded at low frequency range.


### 3.4.1. The Vibration of Piperidinium Cation (H2TMDP)2+

The infrared absorption spectrum of the title compound (H2TMDP) BiCl5 shows corresponding vibration bands of 1,3-bis(4-piperidinium)propane cation. The assignments reported in Table 5 are in agreement with the calculated IR spectrum. These modes are well predicted by the calculation. The shift between the observed wave numbers and the calculated ones is probably due to the approximations used in the computations. However, the groups are assumed to be free whereas actually they are engaged by hydrogen bonds.Heterocyclic compounds containing an N–H group exhibit N–H stretching absorption in the region from 3500 to 3200 cm−1. The stretching vibrations of the N–H group are observed at 3460 and 3110 cm−1. The infrared bands observed at 2980–2850 cm−1 region are assigned CH stretching for piperidine [16, 22]. In the 1,3-bis(4-piperidyl)propane, the stretching of CH modes experimentally are observed at 2920–2856 cm−1 region. The stretching modes of CN are observed around 1180–1100 cm−1 for piperidine [16, 22]. Piperidine ring CC stretching modes are obtained in the range 1350–1073 cm−1 [16, 22]. The C–H stretching absorption of methylene group is centered on 2925 cm−1. The infrared band observed at 2856 cm−1 is assigned to symmetric CH2 for methylene group. The asymmetric stretching mode of methylene group is observed at 2920 cm−1.


### 3.4.2. The Vibration ofBiCl63-

Based on some studies carried out for previous works and reported on similar compounds containing (BiCl5)2- anions [23, 24], we propose an attempt of assignment of the observed bands. The low Raman frequencies of (H2TMDP) BiCl5 crystal can be assigned to vibrations of BiCl63- octahedral corner sharing. The Bi–Cl stretching modes are observed in the low frequency range between 400 and 100 cm−1. The 278 cm−1 and 240 cm−1 bands are, respectively, assigned to the Bi–Cl external ant-symmetric and symmetric stretching. Raman lines at 214, 120, and 100 cm−1 most likely correspond to the Bi–Cl bridging stretch and the Cl–Bi–Cl deformation.


## 3.4.1. The Vibration of Piperidinium Cation (H2TMDP)2+

The infrared absorption spectrum of the title compound (H2TMDP) BiCl5 shows corresponding vibration bands of 1,3-bis(4-piperidinium)propane cation. The assignments reported in Table 5 are in agreement with the calculated IR spectrum. These modes are well predicted by the calculation. The shift between the observed wave numbers and the calculated ones is probably due to the approximations used in the computations. However, the groups are assumed to be free whereas actually they are engaged by hydrogen bonds.Heterocyclic compounds containing an N–H group exhibit N–H stretching absorption in the region from 3500 to 3200 cm−1. The stretching vibrations of the N–H group are observed at 3460 and 3110 cm−1. The infrared bands observed at 2980–2850 cm−1 region are assigned CH stretching for piperidine [16, 22]. In the 1,3-bis(4-piperidyl)propane, the stretching of CH modes experimentally are observed at 2920–2856 cm−1 region. The stretching modes of CN are observed around 1180–1100 cm−1 for piperidine [16, 22]. Piperidine ring CC stretching modes are obtained in the range 1350–1073 cm−1 [16, 22]. The C–H stretching absorption of methylene group is centered on 2925 cm−1. The infrared band observed at 2856 cm−1 is assigned to symmetric CH2 for methylene group. The asymmetric stretching mode of methylene group is observed at 2920 cm−1.


## 3.4.2. The Vibration ofBiCl63-

Based on some studies carried out for previous works and reported on similar compounds containing (BiCl5)2- anions [23, 24], we propose an attempt of assignment of the observed bands. The low Raman frequencies of (H2TMDP) BiCl5 crystal can be assigned to vibrations of BiCl63- octahedral corner sharing. The Bi–Cl stretching modes are observed in the low frequency range between 400 and 100 cm−1. The 278 cm−1 and 240 cm−1 bands are, respectively, assigned to the Bi–Cl external ant-symmetric and symmetric stretching. Raman lines at 214, 120, and 100 cm−1 most likely correspond to the Bi–Cl bridging stretch and the Cl–Bi–Cl deformation.


## 3.5. UV-Visible Spectroscopy

In the UV-Vis absorption the chlorobismuthate(III) anions are characterized by metal centered (MC) sp and Ligand to metal centered transitions (LMCT) at lower wavelengths [25, 26]. In fact, The LMCT may occur only at rather high energies and all long wavelength transitions were assigned to metal-centered transitions [27, 28].The  optical  properties  of  1,3-bis(4-piperidinium)propane  pentachlorobismuthate(III) pellets were assessed by its UV-Vis absorption spectrum shown in Figure10.Figure 10
Diffuse reflectance UV-Visible absorption spectra for (H2TMDP)BiCl5.The (H2TMDP) BiCl5 exhibits two distinct absorptions bands cantered at 287 nm and 410 nm. The highest absorption peak at 410 nm is assigned to the Metal Centered (MC) transition from the 6s to 6s 6p of Bismuth atom. The band at 287 nm can be attributed to Ligand, to metal charge transfer (LMCT) transition from the 5p orbital of Cl to 6p orbital of Bi(III) as described in previous outputs [25–28].


## 4. Conclusions

The pseudo-one-dimensional (1D) organic-inorganic hybrid compound (C13H28N2)BiCl5 consists of polymeric [BiCl5]2− entities with corner sharing BiCl6 octahedral geometry. Piperidinium cations are located in the empty space around BiCl6 chains and linked to the octahedra by hydrogen bonds. The vibrational properties of this structure were studied by Raman scattering and infrared spectroscopy. The assignment of the vibrational bands was performed by comparison with the vibration modes frequencies of homologous compounds and compared with the calculated spectrum. The optical properties were investigated by UV-Visible measurement. The crystal morphology was carried out using the Bravais-Friedel and Donnay-Harker model.



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*Source: 253602-2014-06-02.xml*