Synthesis, crystal structure, physico-chemical characterization and dielectric properties of a new hybrid material, 1-Ethylpiperazine-1,4-diium tetrachlorocadmate

Accepted Manuscript Synthesis, Crystal structure, Physico-Chemical Characterization and Dielectric Properties of a new hybrid material, 1-Ethylpiperazine-1,4-diium tetrachlorocadmate A.C. Dhieb, A. Valkonen, M. Rzaigui, W. Smirani PII:

S0022-2860(15)30232-5

DOI:

10.1016/j.molstruc.2015.08.044

Reference:

MOLSTR 21776

To appear in:

Journal of Molecular Structure

Received Date: 6 July 2015 Revised Date:

14 August 2015

Accepted Date: 18 August 2015

Please cite this article as: A.C. Dhieb, A. Valkonen, M. Rzaigui, W. Smirani, Synthesis, Crystal structure, Physico-Chemical Characterization and Dielectric Properties of a new hybrid material, 1Ethylpiperazine-1,4-diium tetrachlorocadmate, Journal of Molecular Structure (2015), doi: 10.1016/ j.molstruc.2015.08.044. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

Synthesis, Crystal structure, Physico-Chemical Characterization and Dielectric Properties of a new hybrid material, 1-Ethylpiperazine-1,4-diium

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tetrachlorocadmate

A. C. Dhieba, A.Valkonenb, M. Rzaiguia and W. Smirania*

Tunisia

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a- Laboratoire de chimie des matériaux, Faculté des Sciences de Bizerte, Université de Carthage, 7021 zarzouna,

b- Department of Chemistry and Bioengineering, Tampere University of Technology, P. O. Box 541, 33101

Corresponding author: [email protected]

Abstract

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Tampere, Finland

A new organic-inorganic hybrid metal complex, 1-Ethylpiperazine-1,4-diium tetrachlorocadmate was

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synthesized and the structure is determined by single crystal X-Ray diffraction analyses. The title compound crystallizes in the orthorhombic system with space group Pbca. The unit cell parameters are a=11.5129 (2) Å, b=9.7801 (2) Å, c=23.8599 (4) Å with Z=8 and V=2686.56 (8) Å3. The examination of the structure shows that Cd(II) is coordinated by 4 chlorine atoms and adopt a tetrahedral geometry. Three-dimensional frameworks of

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the title compound are produced by N-H...Cl and C-H...Cl hydrogen bonding. IR, Raman and UV-Visible spectroscopies were also used to characterize this complex. Moreover, the fluorescent properties of the compound have been investigated in the solid state at room temperature. Solid state

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C MAS NMR

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spectroscopy results are in agreement with the X-ray structure. Differential scanning calorimetry (DSC) has revealed a structural phase transition of the order-disorder type around 373 K, and dielectric measurements were performed to discuss the mechanism of this phase transition. The evolution of dielectric constant as a function of temperature of the sample has been investigated in order to determine some related parameters. Keywords: X-Ray diffraction, IR-Raman spectroscopies, NMR spectroscopy, Photoluminescence, Phase transition, Dielectric properties.

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ACCEPTED MANUSCRIPT Introduction Nowadays, a great interest has been dedicated to the wide family of organic-inorganic hybrid materials due to their excellent properties and their potential applications in the field of magnetism, luminescence, biochemistry and material science [1-5]. Among these materials, metal halide complexes such as halocadmates (II) have been the center of growing interest for their structural flexibility. The structural chemistry of halocadmates in the solid state is exceptionally diverse in fact they can arise as simple tetrahedral anion CdCl42- or form the backbone of

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chain polymers. In this area the Cd(II) being (d10), presents a variety of coordination numbers and geometries, depending on crystal packing and ligands (octahedral and tetrahedral typically being observed) as well as halide dimensions [6]. Recently various complexes of Cd(II) have been studied by X-ray diffraction and a large part of them have been reported to be formed by polynuclear anions with various polymerization geometries where the anionic sub-lattice of the crystal may consist of either a simple discrete octahedral, one-dimensional chain, or a

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two-to three-dimensional anionic framework [7-10].

Synthesis of (C6H16N2)CdCl4

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Experimental

All chemicals were purchased from Aldrich and were used without further purification. 1-Ethylpiperazine (1 mmol, 0.112 g) and CdCl2.3H2O (1 mmol, 0.237 g), were dissolved in dilute HCl (10 ml, 1 M) and the then stirred for 2 hours. The resultant mixture was slowly evaporated at room temperature. Colorless single crystals of

Materials and Measurements

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the title compound were isolated after 3 days.

The infrared spectrum was recorded in the range 4000–400 cm-1 with a Nicolet IR200 FT-IR Spectrometer at ambient temperature using a sample dispersed in spectroscopically pure KBr pellet. The UV absorption and

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optical diffuse reflectance spectra were measured at room temperature with a Perkin Elmer Lambda 11 UV/Vis spectrophotometer in the range of 200 - 700 nm. As for the Raman spectra, it was recorded on a HORIBA JOBIN–YVON (T64000) spectrometer in the region 50–3500 cm-1. The spectra slit widths were set to maintain a

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resolution of approximately 3 cm-1 and the excitation light was 633 nm. The 13C CP-MAS NMR spectrum was recorded by use of cross polarization from protons (contact time 5 ms) on a Bruker ULTRASHIELD PLUS 500 spectrometer operating at 125.78 MHz with a classical 4 mm probehead allowing spinning rates up to 10 kHz. The chemical shifts are given relative to tetramethylsilane ( δ = 0.0 ppm). Potoluminescence analyses were performed at 25 °C using a SAFAS FLX-Xenius Spectrofluorimeter and the intensities were corrected for the screening effect. The differential scanning calorimetric measurements were performed with the use of the multimodule 92 Setaram analyzer apparatus in the 273-700 K temperature range in the argon flow. The rate of heating was 5 °C. min-1; the mass of the sample was 13.83 mg.

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ACCEPTED MANUSCRIPT The AC conductivity data and electrical measurements of the real and imaginary components of the impedance parameters (Z' and Z'') were made over a range of temperatures (313–403) K. These measurements were performed by using an hp 4192A impedance analyzer. To assure electrical contacts, the two parallel surfaces of the sample (having a cylindrical shape) were coated by a layer of silver paint. The platinum wires and the sample were held in contact by a weak mechanical pressure controlled by a screw/spring system and transmitted by an alumina rod.

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Single-Crystal X-ray Diffraction Measurements

X-ray data were collected at 173 K on an Agilent Super-Nova diffractometer with Atlas detector using mirrormonochromatized Mo-Kα (λ = 0.71073 Å) radiation. The structure was solved and refined using SHELXL-97 [11]. A direct-methods solution was calculated that provided most of the non-hydrogen atoms from the E-map.

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Full-matrix least squares/difference Fourier cycles were performed that located the remaining non-hydrogen atoms. All non-hydrogen atoms were refined with anisotropic displacement parameters. The final full-matrix least squares refinement gave R = 0.030 and wR = 0.071 (w =1/[σ2(Fo2) + (0.0291P)2 +0.7375P] where P =

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(Fo2 + 2Fc2)/3, S = 1.05, ∆ρmax = 0.45 e Å−3and ∆ρmin = −0.99 e Å−3. Results and Discussion

Crystal structure of 1-Ethylpiperazine-1,4-diium tetrachlorocadmate

The X-ray diffraction of the title compound revealed that the asymmetric unit is formed by one (C6H16N2)2+

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cation and one CdCl42- anionic unit (Fig. S1). Further details of the structure analysis are reported in Table 1. Selected angles and bond lengths are presented in Table S1. The hydrogen bonds are given in Table 2. The examination of the structure has shown that the main feature of the atomic arrangement in this compound is the existence of infinite ribbons composed of anionic and cationic groups, spreading along x = 0 and x = 1/2 and

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linked together by one type of hydrogen bond C-H...Cl. The van der Waals interactions between these ribbons

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give rise to a three-dimensional network and add stability to the structure (Fig. S2). In the [CdCl4]2– anion, generally, the Cd-Cl bonds lengths and Cl-Cd-Cl bond angles are not equal to one another, but vary with the environment around the Cl atoms. The value of the Cd-Cl bond lengths are in the range 2.4109(7) Å and 2.5007(6) Å. The Cl-Cd-Cl angles values vary from 103.21(2) ° to 121.98(2) °. Owing to the obvious differences in the Cd-Cl bond lengths and the Cl-Cd-Cl angles (Table S1), these values agree well with those previously reported for Cd(II) salts containing isolated [CdCl4]2- [9,12]. The average values of the Baur distortion indices (ID) of the CdCl42- tetrahedral are calculated using the previous equations (1) and (2) [13]. 



 | − | | − |
 −  −  =  
 −  =         

  

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(1)

(2)

The obtained values are: ID(Cl-Cd-Cl) = 0.0472; ID(Cd-Cl) = 0.0120. These values are in good agreement with those reported previously, clearly indicating that the [CdCl4]2- anion has a slightly distorted tetrahedral stereochemistry [14]. (Fig. 1) shows that the anionic [CdCl4]2- tetrahedra are linked by pairs via four organic cation to form ribbons

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which extend along b direction at z = 0 and z = 1/2. This anionic entities are linked via two types of hydrogen bonds N(1)-H...Cl and C-H...Cl (Table 2). This association generate different hydrogen bonding motifs such as R24(12) and R42(10).

The piperazinium ring adopts a chair conformation as evidenced by the mean deviation (±0.0365 Å) from the

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least square plane defined by the four constituent atoms C1, C2, C3 and C4 and the remaining atoms N1 and N2 displaced from the plane by -0.552 and 0.539 Å, respectively, with the ethyl group occupying an equatorial position. The conformation of the piperazine six-membered ring can be described in terms of Cremer & Pople

0.5663, θ = 2.76 and φ = -3.12.

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Vibrational study of (C6H16N2)CdCl4

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puckering coordinates [15]. In the title compound, the puckering parameters are QT = 0.5670, q2 = 0.0273 q3 =

To obtain more information on the crystal structure of the title compound, we addressed vibrational study using infrared spectroscopy and Raman scattering. The tentative assignment of the observed bands in the IR and Raman spectra of the title compound was assisted by the theoretically predicted frequencies and compared with

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data previously reported for similar compounds [16-22].

The solid state FTIR and Raman spectra at room temperature of (C6H16N2)CdCl4 were recorded in the internal

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vibration region of the 1-Ethylpiperazinium (4,000–400 cm-1) and in the region of the anionic sublattice vibration (400–50 cm-1) (Figs. 2, S3 and S4). The Raman and infrared peaks frequencies are quoted in Table 3. The high frequency domain in the spectra is characterized by N-H and C-H stretching mode, harmonics and combination bands, yet the bands situated at the region 3136-2760 cm-1 and 3150-2790 cm-1 in IR and Raman respectively are ascribed to the stretching mode of NH2+, NH+, CH2, and CH3. The bands observed in the range of 2530-2000 cm-1 in the IR are attributed to the harmonic combination bands, those latter are not detected in the Raman spectra. While the bands observed at 1550-1400 cm-1 and 1560-1450 cm-1 in IR and Raman respectively are attributed to δas(C-N-H) asymmetric bending , and also it can be assigned to N-H bending mode of NH2+ and NH+ . The series of the bands at 1410-1330 cm-1 in Raman spectra are assigned to δ(C-N-H), δ(C-C-H), δ(N-CH) and out of plane bending of (CH2)pip. The weak band at 1304 cm-1 in FTIR spectra is characterized by (C-N)

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ACCEPTED MANUSCRIPT asymmetric stretching vibration the later is detected in Raman spectra at 1310 cm-1 with a strong intensity. The bands observed at 1290-1210 cm-1 in Raman are attributed to out of plane bending and in plane rocking of CH3. However the bands detected at 1200-980 cm-1 and 1200-990cm-1 in IR and Raman respectively are ascribed to stretching vibration of νs (C-C), νas (C-C), νs (C-N) and the deformation δ(C-H). The series of bands observed at the range of 930-540 cm-1 in IR are assigned to rocking deformation ρ(NH2) and

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to the deformation of δ(C-C), δ(C-N) and δ(C-C-N) while the bands observed in the same region of Raman spectra are assigned to Torsion of (CH2)pip, out of plane deformation of (NH2), in plane deformation of (CH2)pip and rocking deformation ρ(NH2) and ρ(CH2)pip.

modes of (C-C-N) and (C-N-C).

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The bands observed at 470-340 cm-1 in Raman spectra are attributed to asymmetric and symmetric bending

According to previous works containing the chlorocadmate anion, the internal vibrational modes of [CdCl4]2-

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anion appear below 300 cm-1 in Raman spectra [6, 23-24].

The asymmetric and symmetric stretching vibration of (Cd-Cl) appeared at 283 and 264 cm-1. The band situated at 137 cm-1 is assigned to the bending mode of (Cd-Cl). However the bands corresponding to the bending mode of Cl-Cd-Cl arise in the region of 130-100 cm-1. The lattice modes can be observed in the Raman spectrum between 95 and 50 cm-1.

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UV Absorption of (C6H16N2)CdCl4

The UV absorption spectrum of (C6H16N2)CdCl4 in water shows one broad band at λ = 304 nm and which extends to λ = 385 nm (Fig. 3a). The origin of this band can be found beyond the classical concepts for the electronic properties in the d10 complexes as it has been pointed out in many studies of similar systems [25, 26].

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Optical diffuse reflectance spectrum (Fig. 3b) indicates an optical band gap of 3.76 eV. The result indicates that the title compound is a semiconductor with wide band gap [27].

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Luminescent properties

It is known that Cd(II) complexes have high photoluminescence quantum yields [28], so to explore the potential application as luminescent materials, solid-state fluorescent properties for the title compound was studied. The PL spectrum of 1-Ethylpiperazine-1,4-diium tetrachlorocadmate at room temperature is represented in Fig. 4. The title compound reveals an intense photoluminescence, and the maximum emission wavelength is at 423 nm upon excitation at 310 nm, this luminescence probably may originate from the ligand-to-metal charge-transfer (LMCT) transition [29]. NMR spectroscopy

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ACCEPTED MANUSCRIPT The 13C NMR spectrum of (C6H16N2)CdCl4 is shown in Fig. S5. It exhibits four signals with respect to six carbon atoms of different chemical environments. The presence of only four lines in this resonance region is due to the fact that some of crystallographically independent carbons have similar chemical environments. This result proves the presence of only one organic cation in the asymmetric unit of the compound. From the spectrum, the peak at δ= 10.20 ppm is due to the presence of C(6)H3 methyl group. The signal of 49.83 ppm is attributed to the C5 carbon atom of the ethyl group. The peaks situated at 43.20 and 52.24 ppm is assigned to C1, C2, C3 and C4

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carbon atoms of the piperazine ring. These results are in good agreement with the crystallographic data. Calorimetric study

The thermal analysis results are reported in Fig. 5. The curve shows two endothermic and one exothermic peak during heating. The shape of the observed scanning anomaly at 373 K suggests the existence of phase transition

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of the 1-Ethylpiperazine-1,4-diium tetrachlorocadmate. The second peak corresponds to the melting of the title compound; this result is confirmed by measure of this temperature by Kofler heating Bank.

and it releases a nauseating gas. Dielectric study

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The exothermic peak observed at 523 K is assigned to degradation of organic groups gives rise to a black residue

The dielectric studies are an important characteristic that can be used to bring information about conduction processes, since it allows the determination of the origin of dielectric losses, electrical and dipolar relaxation

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times and the activation energy [30].

Figs. 6 and 7 show the thermal variation of permittivity ε' and ε'' respectively at different frequencies. An overview of the results from these curves, we can observe one anomaly at about 373 K, attributed to the phase

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transitions detected by DSC.

The permittivity around Ttr =373 K increases considerably as the frequency decrease; this is in agreement with

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the contribution of conductivity in this material [31]. The variation of the loss tangent, Tanδ, with angular frequency at different temperatures is given in Fig. 8, This figure shows the occurrence of one well defined peak that increases from low temperature and presents a maximum below Ttr = 373 K ± 1, then decreases and presents a minimum in the vicinity of Ttr. This transition is characterized by a maximum of ε' and ε'' at 373 K corresponding to a maximum of Tanδ. This dielectric behavior rules out the existence of a ferroelectric phase at high temperature[32], and this transition is manifested by a strong jump in the conductivity plot. So, by increasing the temperature, as a consequence of the disordering of the Cl atoms, the reorientation of the NH2+ and NH+ ions becomes more excited, which contributes to the high conductivity of the material [33].

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ACCEPTED MANUSCRIPT The complex impedance spectra (-Z’’ versus Z’) of the (C6H16N2)(CdCl4) recorded at different temperatures are represented in Fig. 9. As the temperature increases, the semicircles move to a lower value of resistance. So, the complex impedance spectrum shows that the title compound follows the Cole–Cole law [34]. In order to understand the conduction phenomena, we used the Arrhenius modeling equation: σT = A exp (Ea/kbT), where Ea is the activation energy, A is the pre-exponential factor, Kb is the Boltzmann constant, and T

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is the temperature. The thermal evolution of the specific conductivity (log(σT) vs 1,000/T) of the 1-Ethylpiperazine-1,4-diium tetrachlorocadmate is shown in Fig. 10, indicating an Arrhenius-type behavior. We note a change in the slope around the temperature 373 K where two regions of conductivity indicated as A and B are observed. The obtained results confirm the existence of a phase transition in the title compound around the inflection point as

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shown in Fig. 5. However, the activation energy values are relatively weak (Ea1 = 0.11 and Ea2 = 0.058 eV) and are in favour of an electronic conductivity. In all the studied temperature range, this conductivity increases with

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the temperature showing that this material has semiconductor behavior [35].

Dielectric studies confirm the presence of transition phase already detected by thermal analysis using DSC measurement. These led us to believe that the dielectric maximum corresponds to the presence of a transition phase of an order-disorder mechanism. This disordering process is probably related to the lattice dynamic properties, indicating that the cation motions are directly involved in the disordering process [36].

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Conclusion

The present work is devoted to the synthesis and physical–chemical properties of 1-Ethylpiperazine-1,4-diium tetrachlorocadmate, (C6H16N2)CdCl4. The X-Ray diffraction shows the existence of infinite ribbons composed of anionic and cationic groups, spreading along x = 0 and x = 1/2 and linked together by one type of hydrogen bond

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C-H...Cl. The piperazine cations are diprotoned and the CdCl4 tetrahedra are slightly distorted. Moreover, the title compound exhibits a strong fluorescence property at room temperature. The vibrational properties of this structure were studied by Raman scattering and infrared spectroscopy. UV indicates that our compound is a

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semiconductor with wide band gap. The 13C CP-MAS NMR spectrum is in agreement with the X-ray structure. Differential scanning calorimetric and dielectric measurement studies were showed the appearance of phase transition at 373 K.

Supplementary Data

Crystallographic data for the title compound have been deposited at the Cambridge Crystallographic Data Center as supplementary publication (CCDC 1047545). These data can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Center, 12, Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223/336 033; mailto: [email protected]). References

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ACCEPTED MANUSCRIPT 1. K. K. Bisht, A. C. Kathalikkattil, S. Eringathodi. J. Mol. Struct. 1013 (2012) 102 2. J. Jin, M. J. Jia, Y. C. Wang, J. H. Yu, Q. F. Yang, J. Q. Xu. Inorg. Chem. Commun. 14 (2011) 1681. 3. K. Edwards, S. N. Herringer, A. R. Parent, M. Provost, K. C. Shortsleeves, M. M. Turnbull, L. N. Dawe. Inorg. Chem. Acta. 368 (2011) 141.

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4. Y. Jin, C. H. Yu, W. X. Wang, S. C. Li, W. Zhang. Inorg. Chem. Acta. 413 (2014) 97. 5. A. Vishwakarma, P. Ghalsasi, A. Navamoney, Y. Lan, A. Powell. Polyhedron. 30 (2011) 1565. 6. I Chaabane, F. Hlel, K. Guidara. PMC Physics B, 1 (2008) 11.

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7. J. Pons, J. G. Antón, M. F. Bardia, T. Calvet, J. Ros. Inorg Chim Acta. 362 (2009) 2698. 8. I. D. Olekseyuk, L. D. Gulay, I. V. Dydchak, L. V. Piskach, O. V. Parasyuk, O. V. Marchuk. J Alloys Compd.

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14. M. M. Al-Ktaifani, M. K. Rukiah. Chem. Pap. 65 (2011) 469. 15. D. Cremer, J. A. Pople. J. Am. Chem. Soc. 97 (1975) 1354. 16. W. Smirani, C. Ben Nasr, M. Rzaigui. Mat. Res. Bull. 39 (2004) 1103. 17. S. Gunasekaran, B. Anita. Indian J. Pure Appl. Phys. 46 (2008) 833. 18. J. Orive, E. S. Larrea, R. F. De Luis, M. Iglesias, J. L. Mesa, T. Rojoc, M. I. Arriortua. Dalton Trans. 42 (2013) 4500. 19. M. Silverstein, G. C. Basseler, and C. Morill, Spectrometric identification of organic compound (3rd ed, Wiley, New York, 1974).

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ACCEPTED MANUSCRIPT 20. P. Krishnan, K. Gayathri, G. Bhagavannarayana, S. Gunasekaran, G. Anbalagan. Spectrochim. Acta Part A. 102 (2013) 379. 21. V. Krishnakumar, S. Seshadri. Spectrochim. Acta Part A 68 (2007) 833. 22. H. Khili, N. Chaari, A. Madani, N. Ratel-Ramond, J. Jaud, S. Chaabouni. Polyhedron. 48 (2012) 146.

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ACCEPTED MANUSCRIPT Table captions

Table 1: Crystal data and structure refinement

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Table 2: Principal intermolecular hydrogen bonding geometry (Å, °) for (C6H16N2)CdCl4

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Table 3: Observed vibration frequencies (cm-1) and band assignments for (C6H16N2) CdCl4.

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ACCEPTED MANUSCRIPT Table 1: Crystal data and structure refinement C6H16Cl4CdN2

Formula weight

370.41 (g.mol-1)

Temperature (K)

170

Wavelength (Å)

0.71073

Crystal system

orthorhombic

Space group

Pbca

a (Å)

11.5129 (2)

b (Å)

9.7801 (2)

c (Å)

23.8599 (4)

Volume (Å3)

2686.56 (8)

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Empirical formula

Z

8

1.832

Absorption coefficient

2.38 (mm-1)

F(000)

1456

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Dcalc (g.cm-3)

Theta range for data

2.5 to 30.6 deg

collection

Crystal size (mm3)

0.34 × 0.20 × 0.19 –15 <= h <= 9

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Limiting indices

–14 <= l <= 32 7910

reflections observed

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Goodness-of-fit on F²

1.05

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Reflections collected

Final R indices

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–12 <= k<= 13

R1=0.030 and wR2= 0.071

[I > 2 sigma (I)]

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Table 2: Principal intermolecular hydrogen bonding geometry (Å, °) for (C6H16N2)CdCl4 D—H

H···A

D···A

D—H···A

N1—H1···Cl1

0.90

2.34

3.1915

157

N2—H2C···Cl1

0.89

2.49

3.2326

142

N2—H2D···Cl2

0.91

2.29

3.1764

164

C1—H1B···Cl2

0.99

2.78

3.7148

158

C2—H2A···Cl1

0.99

2.81

3.5781

135

C6—H6A···Cl4

0.98

2.82

3.5717

134

C6—H6C···Cl2

0.98

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D—H···A

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2.78

3

3.7554

171

ACCEPTED MANUSCRIPT Table 3: Observed vibration frequencies (cm-1) and band assignments for (C6H16N2) CdCl4. Assignment

90 s 103 sh 137 m 264 s 283 vw

Lattice modes δ(Cl-Cd-Cl) δ(Cd-Cl) νs(Cd-Cl) νas(Cd-Cl)

348 vw 376 w 433 w 470 vw

δ(C-C-N) δ(C-N-C)

902 m

565 w 771 m 819 vw 850 vw 884 vw 905 vw

δ(C-C), δ(C-N) δ(C-C-N) Τ(CH2)pip δop(NH2) δip(CH2)pip ρ(NH2), ρ(CH2)pip

1005 m 1036 vw 1091 m 1194 vw

1001 vw 1047 m 1105 vw 1195 w

νs (C-C) νas (C-C) νs (C-N) δ(C-H)

1227 vw 1276 vw

ρip (CH3) δop(CH3)

1310 s

νas(C-N)

847 vw

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1304 vw

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556 m 776 vw

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Raman (cm-1)

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FT-IR (cm-1)

δ(C-N-H), δ(N-C-H) δ(C-C-H) δop(CH2)pip

1456 w 1470 w 1555 w

δ(NH2+) δ(NH+) δas(C-N-H)

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1421s 1461 m 1548 m

1340 vw 1365 vw 1403 vw

2438 vw

2761 vw 2805 m

3012 s 3163 m

harmonic combination bands

νs(CH3) , νas(CH3) νs(CH2) , νas(CH2)

2801 vw 2888 w 2943 w 2967 vs 2984 w 2996 w 3150 vw

νs (NH+ ) , νas(NH+ ) νs (NH2+) , νas (NH2+)

4

ACCEPTED MANUSCRIPT Figure captions Fig. 1 View of the ribbons showing the R42(10) and R42(12) motifs. Hydrogen bonds are shown as dotted lines

Fig. 3a UV-Visible absorption spectrum of (C6H16N2)CdCl4 Fig. 3b UV diffuse reflectance spectrum for (C6H16N2)CdCl4

RI PT

Fig. 2 Raman spectrum of the (C6H16N2)CdCl4 in the range 50–500 cm-1

SC

Fig. 4 View of the excitation and emission spectra for the title compound in the solid state at room temperature.

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Fig. 5 DSC thermogram of (C6H16N2)CdCl4

Fig. 6 Temperature dependence of the real part of the complex electric permittivity at different frequencies for (C6H16N2)CdCl4

Fig. 7 Temperature dependence of the imaginary part of the complex electric permittivity at

TE D

different frequencies for (C6H16N2)CdCl4

Fig. 8 Variation of the dielectric loss factor (Tan δ) as a function of temperature at various

EP

frequencies for the (C6H16N2)CdCl4

AC C

Fig. 9 Complex impedance diagrams (-Z’’ vs. Z’) for (C6H16N2)CdCl4 at various temperatures Fig. 10 Temperature dependence of the conductivity of (C6H16N2)CdCl4

1

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R2,4(12)

AC C

EP

TE D

R2,4(10)

Fig. 1

2

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TE D

Fig. 2

3

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Fig. 3b

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TE D

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Fig. 3a

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AC C

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TE D

Fig. 4

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AC C

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TE D

Fig. 5

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AC C

EP

TE D

Fig. 6

7

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AC C

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TE D

Fig. 7

8

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AC C

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Fig. 8

9

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AC C

EP

TE D

Fig. 9

10

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AC C

EP

TE D

Fig. 10

11

ACCEPTED MANUSCRIPT New hybrid compound, (C6H16N2)CdCl4, was synthesized at room temperature by slow evaporation. The atomic arrangement shows three-dimensional network. This material was also investigated by IR, Raman and CP-MAS NMR spectroscopies, optical and photoluminescence.

AC C

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The thermogram DSC and the dielectric measurements revealed a phase transition

ACCEPTED MANUSCRIPT Table S1: Bond lengths (Å) and angles (°) for (C6H16N2)CdCl4 (Å)

Bond angles

(°)

Cd(1)−Cl(1)

2.5007(6)

Cl(1)−Cd(1)−Cl(2)

105.43(2)

Cd(1)−Cl(2)

2.4654 (6)

Cl(1)−Cd(1)−Cl(3)

105.63(2)

Cd(1)−Cl(3)

2.4371 (6)

Cl(1)−Cd(1)−Cl(4)

103.21(2)

Cd(1)−Cl(4)

2.4109 (7)

Cl(2)−Cd(1)−Cl(3)

C1-C2

1.520 (3)

Cl(2)−Cd(1)−Cl(4)

C3-C4

1.513 (4)

Cl(3)−Cd(1)−Cl(4)

C5-C6

1.503 (4)

C1−N1−C4

C1-N1

1.496 (3)

C1−N1−C5

C4-N1

1.493(3)

C4−N1−C5

C5-N1

1.512(3)

C2-N2

1.487(3)

C3-N2

1.484 (3)

111.97(2) 121.98(2)

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111.08(19) 112.2(2)

109.22(19) 111.3(2)

C2−C1−N1

111.5 (2)

C3−C4−N1

111.70(19)

C6−C5−N1

112.4 (2)

C1−C2−N2

109.85 (19)

TE D EP

107.18(2)

C2−N2−C3

C4−C3−N2

AC C

RI PT

Bond lengths

110.1 (2)

TE D

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Fig.S1 Asymmetric unit of (C6H16N2)CdCl4 with displacement ellipsoids plotted at 50%

AC C

EP

probability level

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Fig. S2 View of the atomic arrangement of the title compound with hydrogen bonds as dotted lines

TE D

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Fig. S3 IR absorption spectrum of (C6H16N2)CdCl4

TE D

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Fig. S4 Raman spectrum of the (C6H16N2)CdCl4 in the range 500–3500 cm-1

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TE D

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AC C

Fig. S5 13C NMR spectrum of (C6H16N2)CdCl4