- Email: [email protected]
Spectroscopy, crystal structure and molecular conformation of 1-bromo-2, 3, 5, 6- tetra-methylbenzene
Accepted Manuscript Spectroscopy, crystal structure and molecular conformation of 1-bromo-2, 3, 5, 6tetra-methylbenzene Noudjoud Hamdouni, Ali Boudjada, Mohamed Larbi Medjroubi PII:
S0022-2860(19)30918-4
DOI:
https://doi.org/10.1016/j.molstruc.2019.07.074
Reference:
MOLSTR 26827
To appear in:
Journal of Molecular Structure
Received Date: 11 March 2019 Revised Date:
14 July 2019
Accepted Date: 16 July 2019
Please cite this article as: N. Hamdouni, A. Boudjada, M.L. Medjroubi, Spectroscopy, crystal structure and molecular conformation of 1-bromo-2, 3, 5, 6- tetra-methylbenzene, Journal of Molecular Structure (2019), doi: https://doi.org/10.1016/j.molstruc.2019.07.074. 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.
Spectroscopy, crystal structure and molecular conformation of 1-bromo-2, 3, 5, 6ACCEPTED MANUSCRIPT tetra-methylbenzene Noudjoud Hamdouni a, *, Ali Boudjada a, Mohamed Larbi Medjroubi a a
Laboratoire de Cristallographie, Département de Physique, Université Mentouri-Constantine, 25000 Constantine, Algérie
A B S T R A C T
SC
RI PT
The results of SXRD analysis indicate that the 1-Bromo-2,3,5,6-tetramethylbenzene, also known as bromodurene (C10H13Br) has two stable crystalline phases: One below 310K, called α phase, crystallizes in to orthorhombic system, the other above of this temperature, called β phase, crystallizes in to monoclinic system. At room temperature 293 K, this compound crystallizes into orthorhombic system with space group P 212121 symmetry and Z = 4. The crystal structure parameters are a = 5.4241 (7) Å, b =12.0361 (1) Å, c =14.6106 (2) Å, the plane structure of the molecules constituting the asymmetric unit of this compound has been confirmed by X-ray diffraction. An agreement between the DFT calculations and the X -ray diffraction is almost perfect (96% for bond lengths and 85% for bond angles). Then, we show the experimental Raman and FT- IR spectra of bromodurene measured in the range 100-3500 cm-1 and 500-3500 cm-1, respectively. The molecular conformation and vibrational spectra of bromodurene have been investigated theoretically using MPW1PW91 correlation exchange functional and the DGDZVP basis set. The small difference between experimental and calculated modes has been interpreted by intermolecular interactions in the crystal. The Molecular Frontiers Orbitals (FMOS) calculation is carried out to determine the charge transfer within the molecule.
M AN U
Key words: Crystal structure, X-ray diffraction, DFT calculation, spectroscopy, internal modes.
1. Introduction
AC C
EP
TE D
This work is a part of a systematic study about the crystal structure, the molecular conformation and the spectroscopic behavior of the halogenomethylbenzene in the solid state. One of the interests of these materials lies in the fact that they allow to study in details the influence of the molecular environment to perturb their symmetry and in particular the consequences on the spectroscopic properties. The fundamental problems in the molecular crystals are the dynamics of protons, the influence of rotators such as the methyl group (CH3) in structural phase transitions and couplings between rotators. These compounds have found various applications in the agrochemical fields, the pharmacology, the medicinal chemistry [1-3] and in the synthetic textile fibers. This study particularly concerns the understanding of the methyl group’s behavior submitted to different environments from highly symmetrical molecules. The substitution by strongly donor groups CH3 or by acceptor groups (F, Br, I, Cl ...) gives a modification of the hexagonal geometry of the benzene ring by acting on the angles and the bond lengths of the ring [4-8]. Among the benzenic products hexasubstituted by halogens and methyls already studied by our group, the trihalogeno-mesitylenes: trichloromesitylene [9], tribromomesitylene [10], triiodomesitylene [11] and dibromoiodomesitylene [12], all these highly symmetrical molecules, crystallize in the group space of lower symmetry P-1 with the number of molecule per cell Z = 2. These products present disordered phases (order - disorder and vice-versa) according to the temperature, at high temperature the planar molecules make continuous rotations with respect to the axis perpendicular to their mean plane. Generally, in halogen-methylbenzene products, the steric hindrance between halogens and methyls does not appear, since no significant deviation of the atoms from the mean plane of the molecule is observed. We recall that the crystalline structure of the bromodurene established from a powder crystallizes in two different phases [13, 14]: A crystalline phase α established at a temperature below than 310K and corresponds to the orthorhombic crystalline system with Z = 4 and a phase β established at a temperature greater than 310K and corresponds to a monoclinic system with Z = 4. These derivatives are solid at 293 K and their dielectric behavior depends on the nature of the substituent, and in particular of its mass and volume. The dielectric study of Balcou & al [15, 16] on bromodurene showed, around 310 K, the possibility of a phase change, with a high permittivity phase. In order to elucidate the structural properties and conformational behaviors of a molecule, quantum mechanics calculations are very important. Because the interpretation of the experimental results is based on conformational stability [17], they have proved to be an essential tool for the interpretation of experimental results and the prediction of vibrational spectra [18, 19]. In the case of molecules with methyl groups (CH3) surrounded by a heavy substituent atom (Cl, Br or I), a difficulty appears in the assignment of the torsion frequencies of CH3, since they appear in the same frequency range as network vibrations and some internal modes. Herein, we report on one hand the synthesis and crystal structure of bromodurene (C10H13Br) established by X-ray diffraction at 293 K for molecules stacked in a crystal, and on the other hand the molecular conformation and the vibrational modes of this compound from calculations of density functional theory (DFT) [20]. The geometrical optimization study using MPW1PW91 correlation exchange functional, the DGDZVP basis set and the spectral study using FT-IR, FT-Raman analysis were conducted in order to confirm whether a certain correlation exists between molecular structure and vibrational frequencies of bromodurene.
based on the density functional theory (DFT) has very precisely molecular conformations adopted by the isolated molecule of 1-bromo -2, 3, 5 , 6-tetramethylbenzene.
2. Experimental procedures
ACCEPTED MANUSCRIPT led to the likely
2.2. Single crystal X-ray diffraction (SXRD) Data collections of patterns (SXRD) were performed at room temperature, using X calibur diffractometer, equipped with a CCD detector using graphite-monochromatized Mo Kα radiation ( λ = 0.71073 Å). Data reduction was done by CrysAlisPro program. To solve crystalline structure, the SIR 97 [25] program is used. The refinement structure was performed by the full-matrix least square method using the CRYSTALS program [26]. Anisotropic displacement parameters were determined for non-hydrogen atoms. H-atoms were visible on the Fourier difference maps, but placed by geometry and allowed to refine riding on the parent atom. Structure was visualized by the Mercury Software [27]. 2.3. FT-IR spectroscopy
3.1. Crystal structure of bromodurene obtained from X-rays at room temperature The crystal structure of bromodurene was solved by the direct methods; the refinements of the structural factors were carried out by least squares refinements and covered 101 parameters. The compound crystallizes into orthorhombic system with space group P212121 symmetry and Z = 4, as in the isotype iododurene product, detailed in our previous work [33]. At 293 K, the crystal structure parameters are a = 5.4241 (7) Å, b =12.0361 (1) Å, c =14.6106 (2) Å (Table 1) are close to those found by Charbonneau et al. [13, 14]. The detailed fractional atomic coordinates and the equivalent isotropic displacement parameters were deposited in CCDC with the reference number 1904475. The dielectric study of Balcou et al. [15, 16] on bromodurene showed, around 310 K, the possibility of a phase change, with a high permittivity phase. The molecular structure of this compound is illustrated in Fig.1. Calculated and experimental bond angles and lengths are presented in Tables 2 and 3. The stacking molecules are parallel between them following the direction [010]. In the crystal, the Car-Car-Car endocyclic angles opposite to methyls are not equivalent, as observed in the crystal structure of iododurene [33]. The planes defined by atoms C9, C5, C2 and C7 form an angle of 37.7 °. The C10-C6 and C3-C8 bonds have an angle of 17.9 °. The largest endocyclic angle C2-C3-C4 = 123.8 ° is opposite to the methyl Cm8 (Table 2). A difference of 3.1 ° is observed for these two angles located on either side of the CarBr bond length. For a molecule with hexagonal symmetry this difference of 2.7 ° is found for Car-Car-Car endocyclic angles, but in this time on both sides of the Car-H bond. The bond lengths of the carbon-bromine was found to be 1.914 (7) Å. The value of the C3-C4 bond length is 1.349 (4) Ǻ, it is the shortest relative to the other bond lengths of the benzene ring and relative to that found in iododurene (C3-C4 = 1.386 (7)) Å. The average value of Car - Cm bond lengths is 1.505 (4) Å. This mean Car-Cm bond length is slightly longer compared to those found in iododurene. All these values correspond to the values usually found in the literature (Table 3). Among the four Cm-H bonds eclipsed in the mean plane of the molecule as is generally found in the literature in isotype products such as chlorodurene and iododurene, a difference of 10.28 ° is observed for the torsion angle of C5-C6-C10-H102 compared to other dihedral angles C3-C2-C7-H72, C4-C5-C9-H92 and C4-C3-C8-H92 which make, respectively, 1.61, 1.76 and 0.81 °. The plane structure of the molecules constituting the asymmetric unit of this compound has been confirmed by X-ray diffraction compared with those of isotype products (benzene products substituted by halogens and methyls) already found in the literature. Unlike the dihalogénodurenes in this case the dichlorodurene (DCD) [34], the dibromodurene (DBD) [35] and the diiododurene (DID) [36] which present disorders a priori of dynamic origin, the bromodurene (crystalline phase (α)) and the iododurene [32] do not present any disorder. In the case of the dibromdurene, the crystalline study at 293K presents a reorientational disorder which is manifested by leaps of 2π / 3 of the molecule in its mean plane around the axis C3 perpendicular to this plane while passing by its center. In 2002 Britton & al. [36] have determined that the crystalline structure
M AN U
The FT-IR spectra (500-3500 cm-1 region) were recorded on the Jasco (FT/IR-6300) spectrometer at room temperature with with 4.0 cm-1 resolution. Each band is characterized by its value of ν at the maximum of absorption.
3. Results and discussion
RI PT
The compound 1-bromo -2,3,5,6-tetramethylbenzene (BD) was synthesized from durene following Smith and Tohl methods [21-24]. The obtained product was purified after several successive recrystallizations, from an alcoholic solution, then, submitted to a series of zone melting cycles until obtaining perfectly transparent crystals, having needles form.
SC
2.1. Synthesis
2.4. Raman spectroscopy
2.5. Quantum chemical calculations
TE D
The Raman spectra were made with µ-Raman Bruker Senterra in the range of 3500 to 100 cm-1, equipped with a 100 mW laser source operated at λ =785 nm, and aperture setting about 20 ×1000 µm . The raw data collected from the spectrometers are analyzed and processed by the Origin program [28].
AC C
EP
In the present work, the density functional theory (DFT) was used to perform theoretical calculations on the studied compound. Generally, The quantum chemistry methods allow the calculation of the systems electronic structure such as atoms, neutral molecules, ions, surfaces of solids etc…The DFT method has been extensively used due to their accuracy and low computational cost to calculate a wide variety of molecular properties and provided reliable results which are in accordance with experimental data. The geometry of bromodurene was fully optimised with the Gaussian09 program [29] using B3LYP [30] and MPW1PW91 [31] correlation exchange functional and the DGDZVP bases set, which has proven to give a very groundstate geometry and illustrated by Gauss View software program [32]. The vibrational frequency analysis, determined, show that the obtained conformations are at the stationary points corresponding to local minima without any imaginary frequency. The Gauss View software [32] was used for visualization purposes.
The determined vibrational frequency analysis, show that the obtained conformations are corresponding, at the minimal formations energies without any imaginary frequency The calculated vibrational frequencies were compared with the obtained experimental results, simulated, and the observed spectra were also analyzed in detail. Atomic charges of the title compounds computed by Mulliken method and at the MPW1PW91/DGDZVP level of calculation and the DGDZVP base set. A series of calculations
slightly longer compared to those found experimentally (C3-C4 MANUSCRIPT
SC
RI PT
= 1.349 (4) Ǻ and C4-C5 = 1.392 (4) Ǻ (Table 3, Fig. 4). There is a slight difference in the values of the endocyclic and exocyclic angles of the benzene ring for a regular hexagon for each of the two conformations (Table 2). The largest endocyclic angle is 124.77 ° in face of the carbon bonded to the bromine atom for B3LYP and 124.67 ° for MPW1PW91. In each of the two calculated conformations, the Car-Car-Car angles opposite the methyls have a difference of the order of 2 °. The largest exo-cyclic angle is C2-C3-C8, it is adjacent to the C3-C8 bond and is 121.85 ° for B3LYP and 121.71 ° for MPW1PW91 (Fig.4). Largest deviations from the experimental results in the bond angles are observed in Car-Car-Cm. The greatest difference obtained by the two functional (1.86° B3LYP) and (1.96° MPW1PW91) corresponds to the angle C5-C6-C10. The computational and experimental results gave two CmH bonds eclipsed in the mean plane of the molecule and both pointing towards the Car-H bond itself contained in this same plane. In contrast to what is found in the calculations, it is observed in the experiment for the other two methyls a Cm-H bond out of the plane with a dihedral angle of 10.04 °. Experimentally, the crystal structure of BD exhibits bond length and bond angle values much closer to those of the C2v symmetry conformation obtained from the functional MPW1PW91 / DGDZVP. Consequently the calculations of internal vibration modes were undertaken from this functional.
TE D
M AN U
of diiododurene is characterized by the presence of a disorder ACCEPTED of a priori dynamic origin which is manifested by jumps of the molecule in its mean plane. The best mean plane passing through the carbon and the bromine atoms, calculated with the CRYSTALS Molax program, indicates that the angle between the normal at this mean plane is 47.5 °, 72.9 ° and 24.4°, respectively, with respect to the axis a, b and c. In the crystal of title compound, the molecules are stacked along the a axis. Along this direction, the molecules interact with each other by means of Br … Br, Cm … Br, Cm … Cm and C m … Car interactions. At each layer (Fig. 2), the shortest intermolecular distances are as follows: 4.015Å for Br1 ... Car, 3.878 Å for Br1 ... Cm (rBr + rC = 3.55Å (VdW)), 3.778Å for Car ... Cm and 3.712 Å for Cm ... Cm (rC + rC = 3.4 Å (VdW)). The minimum contact distance observed Cm ... Cm is 3.712 Å is responsible for the cohesion of the crystal at the level of the layers stacked along the axis b. The geometry of Br1…Br1 interaction in bromodurene is similar to that observed in iododuren, this distance is larger than the sum of van der Waals radii (rBr = 1.85 Å) (Table 4). For the molecules in different layers, no-coplanar (Fig. 3), the crystalline cohesion is ensured by the interactions between a Cm atom of the methyl and a Car atom of the benzene ring C10 C2 (3.732 Å). This distance is slightly longer than the C9 - C7 (3.712 Å) distance which lies inside coplanar layers. All these distances are close to those of van der Waals at these layers. It is found that in this compound, the interaction of type Cm ... Cm in the same layer, plays an important role in the crystalline stack while in the product isotype iododurene it is the interaction of type Cm ... Car in different layers (noncoplanar layers) that is responsible for the cohesion of the crystal. This difference in the forces at the origin of the cohesion of the crystal between these two derivatives can be at the origin of their different behavior with temperature. Indeed, the number of crystalline phases observed for the BD is greater than in the CD and the ID. 3.2. Molecular conformation of bromodurene obtained from DFT compared to experimental results
AC C
EP
In parallel, we performed calculations based on density functional theory (DFT) to determine very precisely the likely molecular conformations adopted by the isolated bromodurene molecule (C10H13Br). The calculation results from two functionals B3LYP and MPW1PW91 and the DGDZVP base set led to two different conformations of C2v and Cs symmetry with neighboring minimal formation energies. The calculations confirmed that the molecular conformation of C2v symmetry obtained from the functional MPW1PW91 / DGDZVP is the most stable form of this molecule with a conformational energy equal to -10595.65502 eV while that calculated from the functional B3LYP / DGDZVP has a minimum energy of -10592.80933eV. The optimized molecular conformation of bromodurene from DFT is shown in Fig.4. Optimized parameters (bond length and bond angles) calculated by DFT / B3LYP; MPW1PW91 with the DGTZVP base are compared with the experimental data Tables 2 and 3. The correlations between the experimental and the calculated geometric parameters obtained by two methods sets are shown in Fig.(5,6). A comparison between the calculated and the experimental bond lengths and bond angles shows that there is a good correlation. The shorter Car-Car bond lengths of the aromatic ring are adjacent to the Car-H41 bond and correspond to C3-C4 = C4-C5 = 1.399 Ǻ for B3LYP and 1.394 Ǻ for MPW1PW91, but they are
3.3. Frequencies of calculated and experimental vibration modes of bromodurene.
Here we present the results of TFIR and Raman spectroscopy, obtained from the DFT using the functional MPW1PW91 and the basic set DGDZVP that we compare with the experimental results observed in TFIR and Raman. The spectra are reproduced in part in Figures 7 and 8. From the experimental spectrum we have found in part, the calculated frequencies with deviations of a few cm-1. These deviations are due to the thermal agitation of the atoms at room temperature, which are the conditions in which our handling was conducted. These results are acceptable compared to what is generally found in the literature. In Table 5 are given the frequencies of the normal modes calculated, their symmetries and the experimental values. The BD molecule consists of 24 atoms, that is, 66 modes of vibration. This compound is characterized by the presence of four methyl groups, which makes the attribution of their vibrational modes difficult because of the presence of the low frequency modes attributed to the torsion movements CH3. Among the 66 modes of vibration, 41 modes are in the plane and the other 25 are out of the plane. The modes of vibration in the plane are specified by symmetries A1 and B2 and out-ofplane vibration modes by A2 and B1: Г3N-6 = 21A1 + 20B2 + 11A2 + 14B1. 24 modes are active in TFIR and Raman, 10 are active only in Raman, 8 are active only in IR and the other 24 are not active. From an overall point of view, three frequency domains can be distinguished: 18 frequency modes below 600 cm -1, 35 between 600 and 1700 cm-1, and 13 frequency modes above 1700 cm -1 (Table 5). 3.3.1. Vibrations in and out of the methyl group plane According to the literature relative to hexamethylhalogenobenzene compounds, it is reported that the stretching movement of the C-H bond of the CH3 group is around 2900 cm -1. In our case, the anti-symmetric "stretching" motion is located in the frequency range 3145-3152 cm-1 and the symmetrical one is located in the range 3064-3076 cm-1 and 3169-3198 cm-1 in Table 5. These movements are observed experimentally between 2400 and 3000 cm-1 (TFIR and Raman).
respectively. The difference between them was the energy gap. MANUSCRIPT
TE D
3.4. Other molecular properties 3.4.1. Charge analysis
An internal vibrational study of bromodurene (BD) based on a precise determination of the crystal structure by the use of X-ray diffraction was presented. At room temperature, X-ray diffraction established that the C10H13Br structure is much closer to C2v symmetry obtained from MPW1PW91 / DGDZVP functional. The plane structure of the molecules constituting the asymmetric unit of bromoduene was confirmed by X-ray diffraction compared with those of iso types (benzene products substituted by halogens and methyls) already found in the literature. The interaction of type Cm ... Cm in the same layer plays an important role in the crystal growth along the axis a. The results obtained show an agreement of 96% between the bond lengths and bond angles calculated by the functional MPW1PW91/DGDZVP and those obtained by the experience. Geometry optimization using B3LYP and MPW1PW91 correlation exchange functional with the DGDZVP basis set allowed a complete study of the influence of the choice of the base on geometries and vibration frequencies. The vibrational frequencies, infrared intensities, and the Raman activities of the compound are calculated by MPW1PW91/DGDZVP and compared with experimental data. Theoretical calculations of IR and Raman spectroscopy allowed the assignment of 66 internal modes of bromodurene. The small difference between calculated and experimental wave numbers could be a consequence of the presence of vibrations of the intermolecular interactions in the crystals that were completely missing in the DFT calculation.
M AN U
For aromatic products, fundamental harmonics in the plane or out of the molecular plane, the literature locates them in the 840-980 cm-1 range .The frequencies and intensities of these modes are slightly sensitive to the stoichiometry of the nearneighbor atoms. For our case the swing in the plane of the CH3, breathing of the aromatic nucleus as well as the rocking of CH3 occurs between 846 and 1023 cm-1 (symmetry A1 and B2). The bands observed at IR (835 and 984 cm-1) are quite intense but weak at Raman (1020 cm-1). A frequency of 874 cm-1 found in IR corresponds to the out-of-plane swings of the C-H, which is significantly close to that predicted by the calculation of the 888 cm-1 DFT. In the 353-1681 cm-1 region, the observed and calculated BD internal modes are attributed to tangential displacement motions of the aromatic ring and are specified by B2 symmetry. The radial movements of the different bounds are specified by the symmetry A1 and correspond to the following frequencies: 251, 688, 822, 1219, 1325 and 1627 cm-1. At the frequencies 1325 cm-1 and 1627cm-1 calculated and observed correspond the breathing of the benzene nucleus, the Car-Car stretching movements and the umbrella movement of the CH3 table 5.
4. Conclusion
RI PT
3.3.2. Vibration in and out of the molecular plane of the rest of the skeleton of the molecule
It is found to be 6.423 eV.
SC
In the region 84 to 200 cm-1 there areACCEPTED both torsionally induced excitations of the methyl groups, network modes and some internal modes of molecular vibration, are specified by symmetries A1 and B2. These excitations of various origins do not facilitate their attributions because of their coupling, in particular between the methyl rotators and the molecular vibrations. The frequencies calculated by the DFT are generally intense and superior to those observed experimentally.
EP
Atomic charges of the title compounds computed by Mulliken method MPW1PW91/DGDZVP level of calculation are illustrated in Table 6. The magnitudes of the carbon atomic charges for the compound were found to be both positive and negative. These magnitudes were obtained to change between 0.050479 eV and - 0.085968 eV. 3.4.2. Molecular Electrostatic Potential (MEP)
AC C
Electrostatic potential maps, also known as electrostatic potential energy maps, or molecular electrical potential surfaces, illustrate in three dimensionally the charge distributions of molecules. These maps allow us to visualize variably charged regions of a molecule. Knowledge of the charge distributions can be used to determine how molecules interact with one another. In this work, the molecular electrostatic potential surface and the contour map of electrostatic potential of BD have been constructed by the DFT method and is shown in Fig.9. This figure also confirms the different negative and positive potential sites of the molecule in accordance with the total electron density surface. The electrostatic potential of the title compound is in the range - 2.3410-2 V to + 2.34 10-2 V.
Acknowledgement This work was supported by the Laboratoire de Cristallographie, Departement de Physique, Universite´ Constantine1. Algeria, in collaboration with the laboratory of chemical sciences of the University of Rennes 1. We would like to thank Professor J.MEINNEL, who will find here all our gratitude for his contribution and his precious advices for the making of this work. We greatly appreciate the constructive comments of the reviewers. The authors are grateful for his beneficial discussions and suggestions to improve the manuscript and we are very thankful for the help in improving the language of this manuscript.
References [1] [2] [3] [4] [5] [6] [7] [8]
3.4.3. Frontier molecular orbitals (FMOS)
[9]
Both HOMO and LUMO (Fig.10) contribute to chemical reaction. The gap between HOMO and LUMO characterizes the molecular chemical stability. This gap is a measure of electron conduction and hence a decisive parameter in electrical transport properties. The calculated energies values of HOMO and LUMO were -6.667 eV and -0.244 eV,
[10] [11] [12] [13]
K.D. Karlin, Progress in Inorganic Chemistry, vol. 47, 1998, pp. 371e510. NewYork. K. Maeda, Micro. Meso. Mater. 73 (2004) 47e55. J.G. Mao, Coord. Chem. Rev. 251 (2007) 1493e1506. K. Lonsdale. Proc. Roy. Soc. (1929). A 123, 449. K. Lonsdale.. Proc. Roy. Soc. (1931). A 133, 536. K. Takazawa, M.Fujii & M. Ito, J. Phys. Chem. (1993). 99, 3205-3217. E. Richard, R. Walker & J.Weisshar. J. Phys. Chem. (1996). 99, 44514469. E. Richard, R. Walker, K-T Lu & J. Weisshar. J. Phys. Chem. (1995).99, 12422-12433. M. Tazi, J. Meinnel, M. Sanquer, M. Nusimovici, F. Tonnard and R. Carrie. Acta Cryst. (1995). B51, 838-847. J. Meinnel, M. Mani, A.Cousson, F.Boudjada, W.Paulus, M.Johnson.. Chemical Physics. (2000). 261. 165-187. J. Meinnel, A. Boudjada, A. Boucekkine, F. Boudjada, A. Moréac and S. F. Parker.The Journal of Physical Chemistry A (2008). 112 (44). 24- 41. S. Ghanemi, O. Hernandez, A. Boudjadaa and J. Meinnel. Acta Cryst. (2009). C65, o498–o501. G. Charbonneau, J. Baudour, J. C. Messager & J. Meinnel. (1964). Acta Cryst. 17, 780–781.
[22] [23] [24] [25]
[26] [27]
[28] [29]
[30] [31] [32] [33] [34] [35] [36]
RI PT
[21]
SC
[20]
M AN U
[19]
TE D
[18]
EP
[15] [16] [17]
ACCEPTED MANUSCRIPT
G. Charbonneau, J. Baudour, J. C. Messager & J. Meinnel. (1964). Bull. Soc.Fr. Mine´ral. Cristallogr. (1965). 88, 147–148. Y. Balcou, P. Gregoire, J. Meinnel, J. Chem. Phys. (1965). 5, 536. Y. Balcou, J. Meinnel, J. Chem. Phys. (1966). 1, 114. E. Taşal, İ. Sıdır, Y.Gülseven, C.Öğretir, T.Önkol,Journal of Molecular Structure 923 (2009) 141–152. B.A. Hess Jr., J. Schaad, P. Carsky, R. Zahraduik, Chem. Rev. 86 (1986) 709. P. Pulay, X. Zhou, G. Fogarasi, R. Fransto (Ed.), NATO AS Series, vol. C, 406, Kluwer, Dordrecht, (1993), p. 99 R. G. Parr & W. Yang. Density Functional Theory of Atoms and Molecules. Oxford University Press, Oxford. (1989). Smith et al. J. Amer. Chem. Soc. (1933). 55, 1676. Tohl. Berichte. (1892). 25, 1523. Tohl et al. Berichte. (1893). 26, 2944. Smith et al. J. Amer. Chem. Soc. (1936) 7, 58. G. Cascarano, A. Altomare, C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, D.Siliqi, M.C. Burla, G. Polidori , J. Appl. Cryst. (2005).38, 381-388. P. W. Betteridge, J.R. Carruthers, R. I. Cooper, C.K. Prout & D. J. Watkin. J. Appl. Cryst. (2003). 36, 487. C. F. Macrae, I. J. Bruno, J. A. Chisholm, P. R. Edgington, P. McCabe, E. Pidcock, L. Rodriguez- Monge, R. Taylor, J. van de Streek and P. A. Wood, J. Appl. Cryst. (2008). 41, 466- 470. Origin, Microsoft Software, INS. One Rounthouse Palse Nothempton .1110160 USA. Gaussian 03 (Revision A.5), M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, V.G. Zakrzewski, J.A. Montgomery, R.E. Stratmann, J.C. Burant, S. Dapprich, J.M. Millam, A.D. Daniels, K.N. Kudin, M.C. Strain, O. Farkas, J. Tomasi, V. Barone, M. Cossi, R. Cammi, B. Menucci, C. Pomelli, C. Adamo, S. Clifford, J. Ochterski, G.A. Petersson, P.Y. Ayala, Q. Cui, K. Morokuma, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J. Cioslowski, J.V. Ortiz, B.B. Stefanov, G. Liu, A. Liashenko, P. Pikorz, I. Komaromi, R. Gomperts, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, C. Gonzales, M. Challacombe, P.M.W. Gill, B.G. Johnson, W. Chen, M.W. Wong, J.L. Andres, M. Head-Gordon, E. S. Replogle, and J.A. Pople, Gaussian, Inc., Pittsburgh, PA, (2003). A.D. Becke, J. Chem. Phys. (1993). 98. 5648. C. Lee,W. Yang, R.G. Parr, Phys. Rev. (1998). B 37. 785. W. Gaussview, AE. Frisch, A.B. Nielsen, A.J. Holder, Gaussian Inc., Cernegie Office Park, Building 6. Pittsburg, PA 15106, USA. N. Hamdouni, O. Brihi, M. L. Medjroubi, J. Meinnel and A. Boudjada. Iododurene. Acta Cryst. (2012). E68, o3391. J. C. Messager, J. Blot, C. R. A. S. (1971). Paris, 272,684. N. Hamdouni, Spectroscopy, crystal structure of dibromodurene, S.M. Thesis, Dpt. Physical. Frères Mentouri, Univ., Constantine, Algeria, 2008. D. Britton, W. B. Gleson, Acta Cryst. (2003) C59, 0439.
AC C
[14]
Table 1 Crystallographic data and structure refinement parameters. Empirical formula
C10H13Br
Crystal system Molar mass Space group a (Å) b (Å) c (Å) Temperature (K) V (Å3) Z λMoKα (Å) Dcalc (mg/m3) µ(mm-1) F(000) Crystal size (mm3) Crystal color/habit hkl ranges h k l Measured reflections Independent reflections Observed reflections Rint% (sin θ /λ)max (Å-1) Goodness-of-fit on F2 R[F2 > 2 σ (F2)] wR(F2) No. of reflections No. of parameters ∆ ρ max, ∆ ρ min (e Å_3)
Orthorhombic 213.12 P 21 21 21 5.4241(7) 12.0361(1) 14.6106 (2) 293 953.85 (19) 4 0.71073 1.48 4.25 432 0.10×0.08×0.06 White /Needle
RI PT
ACCEPTED MANUSCRIPT
M AN U
SC
-7 → 7 -14→ 14 -19→ 19 2772 1264 1101 0.068 0.672 1.1431 0.0480 0.0551 919 101 0.42, -0.29
Table 2 Some important experimental (X-ray) and theoretical bond length [Å] for Bromodurene
Br1 - C1 C1 - C2 C1 - C6 C2 - C3 C3 - C4 C4 - C5 C5 - C6 C2 - C7 C3 - C8 C5 - C9 C6 - C10 C4 - H41
1.914(7) 1.409(4) 1.387(4) 1.407(4) 1.349(4) 1.392(4) 1.385(4) 1.487(4) 1.523(4) 1.484(4) 1.526(4) 0.927
Calc. B3LYP/ DGDZVP 1.941 1.405 1.405 1.412 1.399 1.399 1.412 1.513 1.516 1.516 1.513 1.088
Bond
MPW1PW91/ DGDZVP 1.916 1.400 1.400 1.405 1.394 1.394 1.405 1.504 1.507 1.507 1.504 1.087
Exp.
B3LYP/ DGDZVP
MPW1PW91/ DGDZVP
0.962 0.957 0.958 0.957 0.961 0.958 0.958 0.960 0.954 0.961 0.959 0.959
1.095 1.090 1.095 1.095 1.093 1.096 1.096 1.093 1.096 1.095 1.090 1.095
1.093 1.089 1.093 1.094 1.091 1.094 1.094 1.091 1.094 1.093 1.089 1.093
C7 - H71 C7 - H72 C7 - H73 C8 - H81 C8 - H82 C8 - H83 C9 - H91 C9 - H92 C9 - H93 C10 - H101 C10 - H102 C10 - H103
Table 3 Some important experimental (X-ray) and theoretical bond angles [°] for Bromodurene
Exp.
Calc.
AC C
Angles
X-ray
Calc.
B3LYP/DGDZVP
MPW1PW91/DGDZVP
Endocyclic Angles
C2-C1-C6 C1-C2-C3 C2-C3-C4 C4-C5-C6 C5- C6 -C1 C3-C4-C5
123,9 (7) 115,6 (7) 120,1(8) 117,4 (8) 118,7 (7) 124,3 (7)
124,77 117,02 119,05 119,05 117,02 123,1
124,67 117,09 119,02 119,02 117,09 123,10
Exocyclic Angles C2-C1-Br1 C6-C1-Br1 C1-C2-C7 C3-C2-C7 C2-C3-C8 C4-C3-C8 C4-C5-C9 C6-C5-C9 C5-C6-C10 C1-C6-C10
117,1 (6) 119.0 (6) 121,8 (8) 122,6 (8) 119,8 (9) 120.0 (9) 119,8(8) 122,7 (8) 119,3 (8) 121,9 (8)
117,61 117,61 121,46 121,52 121,85 119,10 119,10 121,85 121,52 121,46
Table 4 Distances of intermolecular interactions in the crystalline structure of bromodurene
Calc.
X-ray
TE D
Exp. X-ray
EP
Bond
117,67 117,67 121,27 121,64 121,71 119,26 119,26 121,71 121,64 121,27
ACCEPTEDDifferences MANUSCRIPT
Atome
(rXw+ryw)
Interaction distance
X, Y
(Å)
d (Å) In the same layers
Br1-Br1 Br1-Br1 Br1-C3 Br1-C8 C5-C10 C9-C7
3,7 3,7 3,55 3,55 3,4 3,4
7,473 6,082 4,015 3,878 3,778 3,712
Br1-Br1 Br1-C7 C10-Br1 C9-C3 C6-C7 C10-C2
3,7 3,55 3,55 3,4 3,4 3,4
(Å) 3,773 2,382 0,465 0,328 0,378 0,312
5,424 4,437 4,239 3,74 3,734 3,732
1,724 0,887 0,689 0,34 0,334 0,332
rw : Rayon de Van der Waals ; rCw= 1.70 Å,rBrw= 1.85 Å Table 5 Experimental and theoretical vibration frequencies using MPW1PW91/DGDZVP and assignments of Bromodurene
Calculated frequencies (cm_1)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
B1 A2 B1 A2 B1 A2 B2 B1 A1 B1 A1 B2 A2 A1 B2 A1 B1 B2 A2 A1 B1 A1 B2 B1 A1 A1 B2 A2 B1 B1 A2 B2 B2 A1 B2 A1 B2 A1 B2 B2 A1 A1 A1 B2 A2 B1 B2 B1 A2 A1 B2 A1 B2 B2 A1 B2 A1 A2 B1 B1 A2 A1
84.0606 103.2428 128.2006 128.5509 165.7681 200.5049 200.9571 216.5089 251.3294 283.4961 323.9574 352.7649 357.0154 367.3943 443.0147 525.9558 540.4284 561.3335 588.9529 688.0848 729.5574 821.9191 845.7277 887.6289 1014.7537 1023.0117 1038.4989 1042.9516 1047.5653 1067.0520 1071.1199 1071.3350 1104.3573 1219.2187 1274.8221 1324.7388 1341.2491 1413.2391 1426.2567 1433.2715 1435.9367 1451.3961 1496.1981 1496.2998 1503.1126 1503.5450 1523.2487 1526.8543 1527.1415 1534.9278 1540.1443 1627.1472 1680.7028 3064.3835 3064.8542 3075.6026 3076.1546 3144.6064 3144.7614 3151.7089 3151.8504 3169.0695
Calculated Intensity IR
Raman 0.1061 0.0153 0.5684 0.3089 0.0019 0.1457 0.8059 0.3855 3.3086 1.4098 0.2397 0.5065 3.0892 2.5438 5.6083 26.0735 0.7185 0.0585 0.1737 3.3986 2.0383 9.5339 0.1173 0.4110 3.4933 4.3553 0.0204 2.6121 0.3034 1.0970 0.0047 0.0126 1.1370 2.7040 1.2108 22.4944 6.0218 0.4943 15.6473 0.1550 27.0137 2.9251 7.8481 2.2942 18.4107 3.9746 1.0874 10.4071 0.6247 4.6761 0.2666 25.6044 30.4701 20.3204 366.2606 18.5560 335.8467 150.9507 1.4079 77.6739 26.6873 103.1145
IR
EP
AC C
Raman 67 110
209
252 297 352
441
TE D
0.0104 0.0000 1.2566 0.0000 4.2878 0.0000 0.0000 0.2594 2.1505 1.2857 0.1617 0.2929 0.0000 0.0010 0.0441 3.4579 1.8892 0.6771 0.0000 0.8123 0.5436 24.3407 0.0227 9.4274 21.9110 21.6908 7.1753 0.0000 3.8804 0.5863 0.0000 1.9658 1.2371 9.3070 0.8211 5.7667 2.0075 0.1870 0.4397 1.9650 2.4761 8.7200 2.4685 0.1837 0.0000 31.6382 4.3025 0.3151 0.0000 37.1130 37.7712 14.7772 5.0846 52.0728 20.9083 33.0369 8.0217 0.0000 29.4766 12.9848 0.0000 31.5998
Experimental frequencies (cm_1)
Assignments
SC
Sym.
CH3 twist Cm-H Car-Br, Car-Hand ring wagging Cm-H ,Car-H and ring rocking Cm-H and ring rocking Cm-H stretching and ring breathing Cm-H and ring rocking Cm-H ,Car-Br and ring rocking Cm-H, ring rocking Car-Br stretching, Ring breathing Cm-H Car-H and ring Rocking Car-Br stretching,CH3 rocking and ring breathing Cm-H Rocking, ring breathing Cm-H twisting, ring bending Car-Br stretching, Car-H Rocking, ring breathing Cm-H, Car-H and ring wagging Cm-H and ring breathing Cm-H Car-Hand ring wagging Cm-H, Car-H and ring rocking Cm-H and ring wagging Cm-H and ring breathing Cm-H,Car-H and ring rocking Car-Br , Car-H stretching, Cm-H and ring wagging Cm-H ,Car-H rocking and ring stretching Cm-H twisting ,Car-H rocking Cm-H and Car-H twisting, ring breathing CH3and ring wagging Cm-H ,Car-H and ring rocking Cm-H scissors and Ring bending Cm-H, Car-Hand Ring rocking Cm-H ,Car-H and ring wagging Cm-H ,Car-H and ring wagging Cm-H Car-Hand ring wagging Cm-H, Car-Hand Ring rocking CH3 rockine, Ring ip deformation Car-H bending Ring stretching Ring breathing Cm-H,Car-H rocking ,Ring ip deformation Cm-H ,Car-H wagging,Ring ip deformation CH3 umbrella deformation CH3 umbrella deformation , Ring rocking CH3 umbrella deformation ,Car-H, Ring rocking CH3 umbrella deformation,Car-H and ring wagging Cm-H rocking, Car-H ip bend, ring deformation Cm-H wagging Car-H bending Cm-H wagging CH3 umbrella defor,Car-H ip bend,Ring wagging Cm-H rocking Cm-H rocking CH3 umbrella deformation CH3 umbrella deformation, Car-H, Ring rocking CH3 umbrella deformation,Ring stretching Car-H ip bending, Ring stretching Cm-H stretching Cm-H stretching Cm-H stretching Cm-H stretching Cm-H twisting Cm-H twisting Cm-H twisting Cm-H twisting Cm-H stretching
M AN U
No
RI PT
In different layers
796
674 798
874 984 1020
1177 1270 1385 1390
1456 1458 1472
1542
1444
1545 1604
1655
2922
2921 2947
63 64 65 66
B2 B2 A1 A1
47.7201 ACCEPTED MANUSCRIPT
3169.1403 3197.8002 3198.1098 3203.8991
2.6707 27.2286 5.6922 23.2356
0.1135
50.8362 95.5097
Cm-H stretching Cm-H stretching Cm-H stretching Car-H stretching
Table 6 The charges of the atoms determined from natural bond orbital analysis (NBO) by PW1PW91/DGDZVP method MPW1PW91⁄DGDZVP Mulliken
EP
TE D
M AN U
SC
RI PT
0.040924 0.100922 0.149379 -0.503859 0.149379 0.100922 0.219007 -0.755686 0.254228 0.251938 0.251938 -0.755686 0.251938 0.251938 0.254228 -0.762233 0.237536 0.237536 0.242120 -0.762233 0.237536 0.237536 0.242120 -0.171431
AC C
Atoms C C C C C C H C H H H C H H H C H H H C H H H Br
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 2.View of a molecular layer of bromodurene projected in the plane (100) at
TE D
293K. Molecular stacking in the same layer is provided by distance C9··· C7.
Fig. 1.The molecular structure of bromodurene, with atom numbering. The
AC C
EP
displacement ellipsoids are drawn at the 50% probability level.
Fig. 3.View of interactions between parallel molecules of different layers in the crystal structure of C10H13Br. (Codes of symmetry: i) x, y, z; ii) 1 + xy, z. The molecular stacking in different layers is ensured by the distance C10··· C2 (3,732 Å, rc= 1,70 Å).
RI PT
ACCEPTED MANUSCRIPT
Fig. 5. Correlation graphic of calculated and experimental molecular bond
TE D
M AN U
SC
lengths of bromodurene compound.
Fig. 4. Molecular conformation of bromodurene (C2v symmetry) obtained from
AC C
EP
the calculation of the DFT: a) B3LYP / DGDZVP; b) MPW1PW91 / DGDZVP.
Fig. 6. Correlation graphic of calculated and experimental molecular bond angles of bromodurene compound.
RI PT
ACCEPTED MANUSCRIPT
Fig. 7. Experimental and MPW1PW91 / DGDZVP IR spectra of
Fig. 8. Experimental and MPW1PW91 / DGDZVP Raman spectra of Bromodurene.
M AN U
SC
Bromodurene.
(b) The total electron density mapped with electrostatic potential of bromodurene.
AC C
EP
TE D
Fig. 9. (a) The contour map of electrostatic potential of the total density
Fig. 10. HOMO and LUMO plot of bromodurene.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT High lights
EP
TE D
M AN U
SC
RI PT
The compound bromodurene was synthesized from durene. X-ray diffraction was applied to solve molecular structure. Spectral studies using IR, Raman spectroscopy was carry out. The DFT calculation of compound and MEP were examined. The DFT theoretical results were compared with the experimental results.
AC C
S0022-2860(19)30918-4
DOI:
https://doi.org/10.1016/j.molstruc.2019.07.074
Reference:
MOLSTR 26827
To appear in:
Journal of Molecular Structure
Received Date: 11 March 2019 Revised Date:
14 July 2019
Accepted Date: 16 July 2019
Please cite this article as: N. Hamdouni, A. Boudjada, M.L. Medjroubi, Spectroscopy, crystal structure and molecular conformation of 1-bromo-2, 3, 5, 6- tetra-methylbenzene, Journal of Molecular Structure (2019), doi: https://doi.org/10.1016/j.molstruc.2019.07.074. 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.
Spectroscopy, crystal structure and molecular conformation of 1-bromo-2, 3, 5, 6ACCEPTED MANUSCRIPT tetra-methylbenzene Noudjoud Hamdouni a, *, Ali Boudjada a, Mohamed Larbi Medjroubi a a
Laboratoire de Cristallographie, Département de Physique, Université Mentouri-Constantine, 25000 Constantine, Algérie
A B S T R A C T
SC
RI PT
The results of SXRD analysis indicate that the 1-Bromo-2,3,5,6-tetramethylbenzene, also known as bromodurene (C10H13Br) has two stable crystalline phases: One below 310K, called α phase, crystallizes in to orthorhombic system, the other above of this temperature, called β phase, crystallizes in to monoclinic system. At room temperature 293 K, this compound crystallizes into orthorhombic system with space group P 212121 symmetry and Z = 4. The crystal structure parameters are a = 5.4241 (7) Å, b =12.0361 (1) Å, c =14.6106 (2) Å, the plane structure of the molecules constituting the asymmetric unit of this compound has been confirmed by X-ray diffraction. An agreement between the DFT calculations and the X -ray diffraction is almost perfect (96% for bond lengths and 85% for bond angles). Then, we show the experimental Raman and FT- IR spectra of bromodurene measured in the range 100-3500 cm-1 and 500-3500 cm-1, respectively. The molecular conformation and vibrational spectra of bromodurene have been investigated theoretically using MPW1PW91 correlation exchange functional and the DGDZVP basis set. The small difference between experimental and calculated modes has been interpreted by intermolecular interactions in the crystal. The Molecular Frontiers Orbitals (FMOS) calculation is carried out to determine the charge transfer within the molecule.
M AN U
Key words: Crystal structure, X-ray diffraction, DFT calculation, spectroscopy, internal modes.
1. Introduction
AC C
EP
TE D
This work is a part of a systematic study about the crystal structure, the molecular conformation and the spectroscopic behavior of the halogenomethylbenzene in the solid state. One of the interests of these materials lies in the fact that they allow to study in details the influence of the molecular environment to perturb their symmetry and in particular the consequences on the spectroscopic properties. The fundamental problems in the molecular crystals are the dynamics of protons, the influence of rotators such as the methyl group (CH3) in structural phase transitions and couplings between rotators. These compounds have found various applications in the agrochemical fields, the pharmacology, the medicinal chemistry [1-3] and in the synthetic textile fibers. This study particularly concerns the understanding of the methyl group’s behavior submitted to different environments from highly symmetrical molecules. The substitution by strongly donor groups CH3 or by acceptor groups (F, Br, I, Cl ...) gives a modification of the hexagonal geometry of the benzene ring by acting on the angles and the bond lengths of the ring [4-8]. Among the benzenic products hexasubstituted by halogens and methyls already studied by our group, the trihalogeno-mesitylenes: trichloromesitylene [9], tribromomesitylene [10], triiodomesitylene [11] and dibromoiodomesitylene [12], all these highly symmetrical molecules, crystallize in the group space of lower symmetry P-1 with the number of molecule per cell Z = 2. These products present disordered phases (order - disorder and vice-versa) according to the temperature, at high temperature the planar molecules make continuous rotations with respect to the axis perpendicular to their mean plane. Generally, in halogen-methylbenzene products, the steric hindrance between halogens and methyls does not appear, since no significant deviation of the atoms from the mean plane of the molecule is observed. We recall that the crystalline structure of the bromodurene established from a powder crystallizes in two different phases [13, 14]: A crystalline phase α established at a temperature below than 310K and corresponds to the orthorhombic crystalline system with Z = 4 and a phase β established at a temperature greater than 310K and corresponds to a monoclinic system with Z = 4. These derivatives are solid at 293 K and their dielectric behavior depends on the nature of the substituent, and in particular of its mass and volume. The dielectric study of Balcou & al [15, 16] on bromodurene showed, around 310 K, the possibility of a phase change, with a high permittivity phase. In order to elucidate the structural properties and conformational behaviors of a molecule, quantum mechanics calculations are very important. Because the interpretation of the experimental results is based on conformational stability [17], they have proved to be an essential tool for the interpretation of experimental results and the prediction of vibrational spectra [18, 19]. In the case of molecules with methyl groups (CH3) surrounded by a heavy substituent atom (Cl, Br or I), a difficulty appears in the assignment of the torsion frequencies of CH3, since they appear in the same frequency range as network vibrations and some internal modes. Herein, we report on one hand the synthesis and crystal structure of bromodurene (C10H13Br) established by X-ray diffraction at 293 K for molecules stacked in a crystal, and on the other hand the molecular conformation and the vibrational modes of this compound from calculations of density functional theory (DFT) [20]. The geometrical optimization study using MPW1PW91 correlation exchange functional, the DGDZVP basis set and the spectral study using FT-IR, FT-Raman analysis were conducted in order to confirm whether a certain correlation exists between molecular structure and vibrational frequencies of bromodurene.
based on the density functional theory (DFT) has very precisely molecular conformations adopted by the isolated molecule of 1-bromo -2, 3, 5 , 6-tetramethylbenzene.
2. Experimental procedures
ACCEPTED MANUSCRIPT led to the likely
2.2. Single crystal X-ray diffraction (SXRD) Data collections of patterns (SXRD) were performed at room temperature, using X calibur diffractometer, equipped with a CCD detector using graphite-monochromatized Mo Kα radiation ( λ = 0.71073 Å). Data reduction was done by CrysAlisPro program. To solve crystalline structure, the SIR 97 [25] program is used. The refinement structure was performed by the full-matrix least square method using the CRYSTALS program [26]. Anisotropic displacement parameters were determined for non-hydrogen atoms. H-atoms were visible on the Fourier difference maps, but placed by geometry and allowed to refine riding on the parent atom. Structure was visualized by the Mercury Software [27]. 2.3. FT-IR spectroscopy
3.1. Crystal structure of bromodurene obtained from X-rays at room temperature The crystal structure of bromodurene was solved by the direct methods; the refinements of the structural factors were carried out by least squares refinements and covered 101 parameters. The compound crystallizes into orthorhombic system with space group P212121 symmetry and Z = 4, as in the isotype iododurene product, detailed in our previous work [33]. At 293 K, the crystal structure parameters are a = 5.4241 (7) Å, b =12.0361 (1) Å, c =14.6106 (2) Å (Table 1) are close to those found by Charbonneau et al. [13, 14]. The detailed fractional atomic coordinates and the equivalent isotropic displacement parameters were deposited in CCDC with the reference number 1904475. The dielectric study of Balcou et al. [15, 16] on bromodurene showed, around 310 K, the possibility of a phase change, with a high permittivity phase. The molecular structure of this compound is illustrated in Fig.1. Calculated and experimental bond angles and lengths are presented in Tables 2 and 3. The stacking molecules are parallel between them following the direction [010]. In the crystal, the Car-Car-Car endocyclic angles opposite to methyls are not equivalent, as observed in the crystal structure of iododurene [33]. The planes defined by atoms C9, C5, C2 and C7 form an angle of 37.7 °. The C10-C6 and C3-C8 bonds have an angle of 17.9 °. The largest endocyclic angle C2-C3-C4 = 123.8 ° is opposite to the methyl Cm8 (Table 2). A difference of 3.1 ° is observed for these two angles located on either side of the CarBr bond length. For a molecule with hexagonal symmetry this difference of 2.7 ° is found for Car-Car-Car endocyclic angles, but in this time on both sides of the Car-H bond. The bond lengths of the carbon-bromine was found to be 1.914 (7) Å. The value of the C3-C4 bond length is 1.349 (4) Ǻ, it is the shortest relative to the other bond lengths of the benzene ring and relative to that found in iododurene (C3-C4 = 1.386 (7)) Å. The average value of Car - Cm bond lengths is 1.505 (4) Å. This mean Car-Cm bond length is slightly longer compared to those found in iododurene. All these values correspond to the values usually found in the literature (Table 3). Among the four Cm-H bonds eclipsed in the mean plane of the molecule as is generally found in the literature in isotype products such as chlorodurene and iododurene, a difference of 10.28 ° is observed for the torsion angle of C5-C6-C10-H102 compared to other dihedral angles C3-C2-C7-H72, C4-C5-C9-H92 and C4-C3-C8-H92 which make, respectively, 1.61, 1.76 and 0.81 °. The plane structure of the molecules constituting the asymmetric unit of this compound has been confirmed by X-ray diffraction compared with those of isotype products (benzene products substituted by halogens and methyls) already found in the literature. Unlike the dihalogénodurenes in this case the dichlorodurene (DCD) [34], the dibromodurene (DBD) [35] and the diiododurene (DID) [36] which present disorders a priori of dynamic origin, the bromodurene (crystalline phase (α)) and the iododurene [32] do not present any disorder. In the case of the dibromdurene, the crystalline study at 293K presents a reorientational disorder which is manifested by leaps of 2π / 3 of the molecule in its mean plane around the axis C3 perpendicular to this plane while passing by its center. In 2002 Britton & al. [36] have determined that the crystalline structure
M AN U
The FT-IR spectra (500-3500 cm-1 region) were recorded on the Jasco (FT/IR-6300) spectrometer at room temperature with with 4.0 cm-1 resolution. Each band is characterized by its value of ν at the maximum of absorption.
3. Results and discussion
RI PT
The compound 1-bromo -2,3,5,6-tetramethylbenzene (BD) was synthesized from durene following Smith and Tohl methods [21-24]. The obtained product was purified after several successive recrystallizations, from an alcoholic solution, then, submitted to a series of zone melting cycles until obtaining perfectly transparent crystals, having needles form.
SC
2.1. Synthesis
2.4. Raman spectroscopy
2.5. Quantum chemical calculations
TE D
The Raman spectra were made with µ-Raman Bruker Senterra in the range of 3500 to 100 cm-1, equipped with a 100 mW laser source operated at λ =785 nm, and aperture setting about 20 ×1000 µm . The raw data collected from the spectrometers are analyzed and processed by the Origin program [28].
AC C
EP
In the present work, the density functional theory (DFT) was used to perform theoretical calculations on the studied compound. Generally, The quantum chemistry methods allow the calculation of the systems electronic structure such as atoms, neutral molecules, ions, surfaces of solids etc…The DFT method has been extensively used due to their accuracy and low computational cost to calculate a wide variety of molecular properties and provided reliable results which are in accordance with experimental data. The geometry of bromodurene was fully optimised with the Gaussian09 program [29] using B3LYP [30] and MPW1PW91 [31] correlation exchange functional and the DGDZVP bases set, which has proven to give a very groundstate geometry and illustrated by Gauss View software program [32]. The vibrational frequency analysis, determined, show that the obtained conformations are at the stationary points corresponding to local minima without any imaginary frequency. The Gauss View software [32] was used for visualization purposes.
The determined vibrational frequency analysis, show that the obtained conformations are corresponding, at the minimal formations energies without any imaginary frequency The calculated vibrational frequencies were compared with the obtained experimental results, simulated, and the observed spectra were also analyzed in detail. Atomic charges of the title compounds computed by Mulliken method and at the MPW1PW91/DGDZVP level of calculation and the DGDZVP base set. A series of calculations
slightly longer compared to those found experimentally (C3-C4 MANUSCRIPT
SC
RI PT
= 1.349 (4) Ǻ and C4-C5 = 1.392 (4) Ǻ (Table 3, Fig. 4). There is a slight difference in the values of the endocyclic and exocyclic angles of the benzene ring for a regular hexagon for each of the two conformations (Table 2). The largest endocyclic angle is 124.77 ° in face of the carbon bonded to the bromine atom for B3LYP and 124.67 ° for MPW1PW91. In each of the two calculated conformations, the Car-Car-Car angles opposite the methyls have a difference of the order of 2 °. The largest exo-cyclic angle is C2-C3-C8, it is adjacent to the C3-C8 bond and is 121.85 ° for B3LYP and 121.71 ° for MPW1PW91 (Fig.4). Largest deviations from the experimental results in the bond angles are observed in Car-Car-Cm. The greatest difference obtained by the two functional (1.86° B3LYP) and (1.96° MPW1PW91) corresponds to the angle C5-C6-C10. The computational and experimental results gave two CmH bonds eclipsed in the mean plane of the molecule and both pointing towards the Car-H bond itself contained in this same plane. In contrast to what is found in the calculations, it is observed in the experiment for the other two methyls a Cm-H bond out of the plane with a dihedral angle of 10.04 °. Experimentally, the crystal structure of BD exhibits bond length and bond angle values much closer to those of the C2v symmetry conformation obtained from the functional MPW1PW91 / DGDZVP. Consequently the calculations of internal vibration modes were undertaken from this functional.
TE D
M AN U
of diiododurene is characterized by the presence of a disorder ACCEPTED of a priori dynamic origin which is manifested by jumps of the molecule in its mean plane. The best mean plane passing through the carbon and the bromine atoms, calculated with the CRYSTALS Molax program, indicates that the angle between the normal at this mean plane is 47.5 °, 72.9 ° and 24.4°, respectively, with respect to the axis a, b and c. In the crystal of title compound, the molecules are stacked along the a axis. Along this direction, the molecules interact with each other by means of Br … Br, Cm … Br, Cm … Cm and C m … Car interactions. At each layer (Fig. 2), the shortest intermolecular distances are as follows: 4.015Å for Br1 ... Car, 3.878 Å for Br1 ... Cm (rBr + rC = 3.55Å (VdW)), 3.778Å for Car ... Cm and 3.712 Å for Cm ... Cm (rC + rC = 3.4 Å (VdW)). The minimum contact distance observed Cm ... Cm is 3.712 Å is responsible for the cohesion of the crystal at the level of the layers stacked along the axis b. The geometry of Br1…Br1 interaction in bromodurene is similar to that observed in iododuren, this distance is larger than the sum of van der Waals radii (rBr = 1.85 Å) (Table 4). For the molecules in different layers, no-coplanar (Fig. 3), the crystalline cohesion is ensured by the interactions between a Cm atom of the methyl and a Car atom of the benzene ring C10 C2 (3.732 Å). This distance is slightly longer than the C9 - C7 (3.712 Å) distance which lies inside coplanar layers. All these distances are close to those of van der Waals at these layers. It is found that in this compound, the interaction of type Cm ... Cm in the same layer, plays an important role in the crystalline stack while in the product isotype iododurene it is the interaction of type Cm ... Car in different layers (noncoplanar layers) that is responsible for the cohesion of the crystal. This difference in the forces at the origin of the cohesion of the crystal between these two derivatives can be at the origin of their different behavior with temperature. Indeed, the number of crystalline phases observed for the BD is greater than in the CD and the ID. 3.2. Molecular conformation of bromodurene obtained from DFT compared to experimental results
AC C
EP
In parallel, we performed calculations based on density functional theory (DFT) to determine very precisely the likely molecular conformations adopted by the isolated bromodurene molecule (C10H13Br). The calculation results from two functionals B3LYP and MPW1PW91 and the DGDZVP base set led to two different conformations of C2v and Cs symmetry with neighboring minimal formation energies. The calculations confirmed that the molecular conformation of C2v symmetry obtained from the functional MPW1PW91 / DGDZVP is the most stable form of this molecule with a conformational energy equal to -10595.65502 eV while that calculated from the functional B3LYP / DGDZVP has a minimum energy of -10592.80933eV. The optimized molecular conformation of bromodurene from DFT is shown in Fig.4. Optimized parameters (bond length and bond angles) calculated by DFT / B3LYP; MPW1PW91 with the DGTZVP base are compared with the experimental data Tables 2 and 3. The correlations between the experimental and the calculated geometric parameters obtained by two methods sets are shown in Fig.(5,6). A comparison between the calculated and the experimental bond lengths and bond angles shows that there is a good correlation. The shorter Car-Car bond lengths of the aromatic ring are adjacent to the Car-H41 bond and correspond to C3-C4 = C4-C5 = 1.399 Ǻ for B3LYP and 1.394 Ǻ for MPW1PW91, but they are
3.3. Frequencies of calculated and experimental vibration modes of bromodurene.
Here we present the results of TFIR and Raman spectroscopy, obtained from the DFT using the functional MPW1PW91 and the basic set DGDZVP that we compare with the experimental results observed in TFIR and Raman. The spectra are reproduced in part in Figures 7 and 8. From the experimental spectrum we have found in part, the calculated frequencies with deviations of a few cm-1. These deviations are due to the thermal agitation of the atoms at room temperature, which are the conditions in which our handling was conducted. These results are acceptable compared to what is generally found in the literature. In Table 5 are given the frequencies of the normal modes calculated, their symmetries and the experimental values. The BD molecule consists of 24 atoms, that is, 66 modes of vibration. This compound is characterized by the presence of four methyl groups, which makes the attribution of their vibrational modes difficult because of the presence of the low frequency modes attributed to the torsion movements CH3. Among the 66 modes of vibration, 41 modes are in the plane and the other 25 are out of the plane. The modes of vibration in the plane are specified by symmetries A1 and B2 and out-ofplane vibration modes by A2 and B1: Г3N-6 = 21A1 + 20B2 + 11A2 + 14B1. 24 modes are active in TFIR and Raman, 10 are active only in Raman, 8 are active only in IR and the other 24 are not active. From an overall point of view, three frequency domains can be distinguished: 18 frequency modes below 600 cm -1, 35 between 600 and 1700 cm-1, and 13 frequency modes above 1700 cm -1 (Table 5). 3.3.1. Vibrations in and out of the methyl group plane According to the literature relative to hexamethylhalogenobenzene compounds, it is reported that the stretching movement of the C-H bond of the CH3 group is around 2900 cm -1. In our case, the anti-symmetric "stretching" motion is located in the frequency range 3145-3152 cm-1 and the symmetrical one is located in the range 3064-3076 cm-1 and 3169-3198 cm-1 in Table 5. These movements are observed experimentally between 2400 and 3000 cm-1 (TFIR and Raman).
respectively. The difference between them was the energy gap. MANUSCRIPT
TE D
3.4. Other molecular properties 3.4.1. Charge analysis
An internal vibrational study of bromodurene (BD) based on a precise determination of the crystal structure by the use of X-ray diffraction was presented. At room temperature, X-ray diffraction established that the C10H13Br structure is much closer to C2v symmetry obtained from MPW1PW91 / DGDZVP functional. The plane structure of the molecules constituting the asymmetric unit of bromoduene was confirmed by X-ray diffraction compared with those of iso types (benzene products substituted by halogens and methyls) already found in the literature. The interaction of type Cm ... Cm in the same layer plays an important role in the crystal growth along the axis a. The results obtained show an agreement of 96% between the bond lengths and bond angles calculated by the functional MPW1PW91/DGDZVP and those obtained by the experience. Geometry optimization using B3LYP and MPW1PW91 correlation exchange functional with the DGDZVP basis set allowed a complete study of the influence of the choice of the base on geometries and vibration frequencies. The vibrational frequencies, infrared intensities, and the Raman activities of the compound are calculated by MPW1PW91/DGDZVP and compared with experimental data. Theoretical calculations of IR and Raman spectroscopy allowed the assignment of 66 internal modes of bromodurene. The small difference between calculated and experimental wave numbers could be a consequence of the presence of vibrations of the intermolecular interactions in the crystals that were completely missing in the DFT calculation.
M AN U
For aromatic products, fundamental harmonics in the plane or out of the molecular plane, the literature locates them in the 840-980 cm-1 range .The frequencies and intensities of these modes are slightly sensitive to the stoichiometry of the nearneighbor atoms. For our case the swing in the plane of the CH3, breathing of the aromatic nucleus as well as the rocking of CH3 occurs between 846 and 1023 cm-1 (symmetry A1 and B2). The bands observed at IR (835 and 984 cm-1) are quite intense but weak at Raman (1020 cm-1). A frequency of 874 cm-1 found in IR corresponds to the out-of-plane swings of the C-H, which is significantly close to that predicted by the calculation of the 888 cm-1 DFT. In the 353-1681 cm-1 region, the observed and calculated BD internal modes are attributed to tangential displacement motions of the aromatic ring and are specified by B2 symmetry. The radial movements of the different bounds are specified by the symmetry A1 and correspond to the following frequencies: 251, 688, 822, 1219, 1325 and 1627 cm-1. At the frequencies 1325 cm-1 and 1627cm-1 calculated and observed correspond the breathing of the benzene nucleus, the Car-Car stretching movements and the umbrella movement of the CH3 table 5.
4. Conclusion
RI PT
3.3.2. Vibration in and out of the molecular plane of the rest of the skeleton of the molecule
It is found to be 6.423 eV.
SC
In the region 84 to 200 cm-1 there areACCEPTED both torsionally induced excitations of the methyl groups, network modes and some internal modes of molecular vibration, are specified by symmetries A1 and B2. These excitations of various origins do not facilitate their attributions because of their coupling, in particular between the methyl rotators and the molecular vibrations. The frequencies calculated by the DFT are generally intense and superior to those observed experimentally.
EP
Atomic charges of the title compounds computed by Mulliken method MPW1PW91/DGDZVP level of calculation are illustrated in Table 6. The magnitudes of the carbon atomic charges for the compound were found to be both positive and negative. These magnitudes were obtained to change between 0.050479 eV and - 0.085968 eV. 3.4.2. Molecular Electrostatic Potential (MEP)
AC C
Electrostatic potential maps, also known as electrostatic potential energy maps, or molecular electrical potential surfaces, illustrate in three dimensionally the charge distributions of molecules. These maps allow us to visualize variably charged regions of a molecule. Knowledge of the charge distributions can be used to determine how molecules interact with one another. In this work, the molecular electrostatic potential surface and the contour map of electrostatic potential of BD have been constructed by the DFT method and is shown in Fig.9. This figure also confirms the different negative and positive potential sites of the molecule in accordance with the total electron density surface. The electrostatic potential of the title compound is in the range - 2.3410-2 V to + 2.34 10-2 V.
Acknowledgement This work was supported by the Laboratoire de Cristallographie, Departement de Physique, Universite´ Constantine1. Algeria, in collaboration with the laboratory of chemical sciences of the University of Rennes 1. We would like to thank Professor J.MEINNEL, who will find here all our gratitude for his contribution and his precious advices for the making of this work. We greatly appreciate the constructive comments of the reviewers. The authors are grateful for his beneficial discussions and suggestions to improve the manuscript and we are very thankful for the help in improving the language of this manuscript.
References [1] [2] [3] [4] [5] [6] [7] [8]
3.4.3. Frontier molecular orbitals (FMOS)
[9]
Both HOMO and LUMO (Fig.10) contribute to chemical reaction. The gap between HOMO and LUMO characterizes the molecular chemical stability. This gap is a measure of electron conduction and hence a decisive parameter in electrical transport properties. The calculated energies values of HOMO and LUMO were -6.667 eV and -0.244 eV,
[10] [11] [12] [13]
K.D. Karlin, Progress in Inorganic Chemistry, vol. 47, 1998, pp. 371e510. NewYork. K. Maeda, Micro. Meso. Mater. 73 (2004) 47e55. J.G. Mao, Coord. Chem. Rev. 251 (2007) 1493e1506. K. Lonsdale. Proc. Roy. Soc. (1929). A 123, 449. K. Lonsdale.. Proc. Roy. Soc. (1931). A 133, 536. K. Takazawa, M.Fujii & M. Ito, J. Phys. Chem. (1993). 99, 3205-3217. E. Richard, R. Walker & J.Weisshar. J. Phys. Chem. (1996). 99, 44514469. E. Richard, R. Walker, K-T Lu & J. Weisshar. J. Phys. Chem. (1995).99, 12422-12433. M. Tazi, J. Meinnel, M. Sanquer, M. Nusimovici, F. Tonnard and R. Carrie. Acta Cryst. (1995). B51, 838-847. J. Meinnel, M. Mani, A.Cousson, F.Boudjada, W.Paulus, M.Johnson.. Chemical Physics. (2000). 261. 165-187. J. Meinnel, A. Boudjada, A. Boucekkine, F. Boudjada, A. Moréac and S. F. Parker.The Journal of Physical Chemistry A (2008). 112 (44). 24- 41. S. Ghanemi, O. Hernandez, A. Boudjadaa and J. Meinnel. Acta Cryst. (2009). C65, o498–o501. G. Charbonneau, J. Baudour, J. C. Messager & J. Meinnel. (1964). Acta Cryst. 17, 780–781.
[22] [23] [24] [25]
[26] [27]
[28] [29]
[30] [31] [32] [33] [34] [35] [36]
RI PT
[21]
SC
[20]
M AN U
[19]
TE D
[18]
EP
[15] [16] [17]
ACCEPTED MANUSCRIPT
G. Charbonneau, J. Baudour, J. C. Messager & J. Meinnel. (1964). Bull. Soc.Fr. Mine´ral. Cristallogr. (1965). 88, 147–148. Y. Balcou, P. Gregoire, J. Meinnel, J. Chem. Phys. (1965). 5, 536. Y. Balcou, J. Meinnel, J. Chem. Phys. (1966). 1, 114. E. Taşal, İ. Sıdır, Y.Gülseven, C.Öğretir, T.Önkol,Journal of Molecular Structure 923 (2009) 141–152. B.A. Hess Jr., J. Schaad, P. Carsky, R. Zahraduik, Chem. Rev. 86 (1986) 709. P. Pulay, X. Zhou, G. Fogarasi, R. Fransto (Ed.), NATO AS Series, vol. C, 406, Kluwer, Dordrecht, (1993), p. 99 R. G. Parr & W. Yang. Density Functional Theory of Atoms and Molecules. Oxford University Press, Oxford. (1989). Smith et al. J. Amer. Chem. Soc. (1933). 55, 1676. Tohl. Berichte. (1892). 25, 1523. Tohl et al. Berichte. (1893). 26, 2944. Smith et al. J. Amer. Chem. Soc. (1936) 7, 58. G. Cascarano, A. Altomare, C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, D.Siliqi, M.C. Burla, G. Polidori , J. Appl. Cryst. (2005).38, 381-388. P. W. Betteridge, J.R. Carruthers, R. I. Cooper, C.K. Prout & D. J. Watkin. J. Appl. Cryst. (2003). 36, 487. C. F. Macrae, I. J. Bruno, J. A. Chisholm, P. R. Edgington, P. McCabe, E. Pidcock, L. Rodriguez- Monge, R. Taylor, J. van de Streek and P. A. Wood, J. Appl. Cryst. (2008). 41, 466- 470. Origin, Microsoft Software, INS. One Rounthouse Palse Nothempton .1110160 USA. Gaussian 03 (Revision A.5), M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, V.G. Zakrzewski, J.A. Montgomery, R.E. Stratmann, J.C. Burant, S. Dapprich, J.M. Millam, A.D. Daniels, K.N. Kudin, M.C. Strain, O. Farkas, J. Tomasi, V. Barone, M. Cossi, R. Cammi, B. Menucci, C. Pomelli, C. Adamo, S. Clifford, J. Ochterski, G.A. Petersson, P.Y. Ayala, Q. Cui, K. Morokuma, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J. Cioslowski, J.V. Ortiz, B.B. Stefanov, G. Liu, A. Liashenko, P. Pikorz, I. Komaromi, R. Gomperts, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, C. Gonzales, M. Challacombe, P.M.W. Gill, B.G. Johnson, W. Chen, M.W. Wong, J.L. Andres, M. Head-Gordon, E. S. Replogle, and J.A. Pople, Gaussian, Inc., Pittsburgh, PA, (2003). A.D. Becke, J. Chem. Phys. (1993). 98. 5648. C. Lee,W. Yang, R.G. Parr, Phys. Rev. (1998). B 37. 785. W. Gaussview, AE. Frisch, A.B. Nielsen, A.J. Holder, Gaussian Inc., Cernegie Office Park, Building 6. Pittsburg, PA 15106, USA. N. Hamdouni, O. Brihi, M. L. Medjroubi, J. Meinnel and A. Boudjada. Iododurene. Acta Cryst. (2012). E68, o3391. J. C. Messager, J. Blot, C. R. A. S. (1971). Paris, 272,684. N. Hamdouni, Spectroscopy, crystal structure of dibromodurene, S.M. Thesis, Dpt. Physical. Frères Mentouri, Univ., Constantine, Algeria, 2008. D. Britton, W. B. Gleson, Acta Cryst. (2003) C59, 0439.
AC C
[14]
Table 1 Crystallographic data and structure refinement parameters. Empirical formula
C10H13Br
Crystal system Molar mass Space group a (Å) b (Å) c (Å) Temperature (K) V (Å3) Z λMoKα (Å) Dcalc (mg/m3) µ(mm-1) F(000) Crystal size (mm3) Crystal color/habit hkl ranges h k l Measured reflections Independent reflections Observed reflections Rint% (sin θ /λ)max (Å-1) Goodness-of-fit on F2 R[F2 > 2 σ (F2)] wR(F2) No. of reflections No. of parameters ∆ ρ max, ∆ ρ min (e Å_3)
Orthorhombic 213.12 P 21 21 21 5.4241(7) 12.0361(1) 14.6106 (2) 293 953.85 (19) 4 0.71073 1.48 4.25 432 0.10×0.08×0.06 White /Needle
RI PT
ACCEPTED MANUSCRIPT
M AN U
SC
-7 → 7 -14→ 14 -19→ 19 2772 1264 1101 0.068 0.672 1.1431 0.0480 0.0551 919 101 0.42, -0.29
Table 2 Some important experimental (X-ray) and theoretical bond length [Å] for Bromodurene
Br1 - C1 C1 - C2 C1 - C6 C2 - C3 C3 - C4 C4 - C5 C5 - C6 C2 - C7 C3 - C8 C5 - C9 C6 - C10 C4 - H41
1.914(7) 1.409(4) 1.387(4) 1.407(4) 1.349(4) 1.392(4) 1.385(4) 1.487(4) 1.523(4) 1.484(4) 1.526(4) 0.927
Calc. B3LYP/ DGDZVP 1.941 1.405 1.405 1.412 1.399 1.399 1.412 1.513 1.516 1.516 1.513 1.088
Bond
MPW1PW91/ DGDZVP 1.916 1.400 1.400 1.405 1.394 1.394 1.405 1.504 1.507 1.507 1.504 1.087
Exp.
B3LYP/ DGDZVP
MPW1PW91/ DGDZVP
0.962 0.957 0.958 0.957 0.961 0.958 0.958 0.960 0.954 0.961 0.959 0.959
1.095 1.090 1.095 1.095 1.093 1.096 1.096 1.093 1.096 1.095 1.090 1.095
1.093 1.089 1.093 1.094 1.091 1.094 1.094 1.091 1.094 1.093 1.089 1.093
C7 - H71 C7 - H72 C7 - H73 C8 - H81 C8 - H82 C8 - H83 C9 - H91 C9 - H92 C9 - H93 C10 - H101 C10 - H102 C10 - H103
Table 3 Some important experimental (X-ray) and theoretical bond angles [°] for Bromodurene
Exp.
Calc.
AC C
Angles
X-ray
Calc.
B3LYP/DGDZVP
MPW1PW91/DGDZVP
Endocyclic Angles
C2-C1-C6 C1-C2-C3 C2-C3-C4 C4-C5-C6 C5- C6 -C1 C3-C4-C5
123,9 (7) 115,6 (7) 120,1(8) 117,4 (8) 118,7 (7) 124,3 (7)
124,77 117,02 119,05 119,05 117,02 123,1
124,67 117,09 119,02 119,02 117,09 123,10
Exocyclic Angles C2-C1-Br1 C6-C1-Br1 C1-C2-C7 C3-C2-C7 C2-C3-C8 C4-C3-C8 C4-C5-C9 C6-C5-C9 C5-C6-C10 C1-C6-C10
117,1 (6) 119.0 (6) 121,8 (8) 122,6 (8) 119,8 (9) 120.0 (9) 119,8(8) 122,7 (8) 119,3 (8) 121,9 (8)
117,61 117,61 121,46 121,52 121,85 119,10 119,10 121,85 121,52 121,46
Table 4 Distances of intermolecular interactions in the crystalline structure of bromodurene
Calc.
X-ray
TE D
Exp. X-ray
EP
Bond
117,67 117,67 121,27 121,64 121,71 119,26 119,26 121,71 121,64 121,27
ACCEPTEDDifferences MANUSCRIPT
Atome
(rXw+ryw)
Interaction distance
X, Y
(Å)
d (Å) In the same layers
Br1-Br1 Br1-Br1 Br1-C3 Br1-C8 C5-C10 C9-C7
3,7 3,7 3,55 3,55 3,4 3,4
7,473 6,082 4,015 3,878 3,778 3,712
Br1-Br1 Br1-C7 C10-Br1 C9-C3 C6-C7 C10-C2
3,7 3,55 3,55 3,4 3,4 3,4
(Å) 3,773 2,382 0,465 0,328 0,378 0,312
5,424 4,437 4,239 3,74 3,734 3,732
1,724 0,887 0,689 0,34 0,334 0,332
rw : Rayon de Van der Waals ; rCw= 1.70 Å,rBrw= 1.85 Å Table 5 Experimental and theoretical vibration frequencies using MPW1PW91/DGDZVP and assignments of Bromodurene
Calculated frequencies (cm_1)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
B1 A2 B1 A2 B1 A2 B2 B1 A1 B1 A1 B2 A2 A1 B2 A1 B1 B2 A2 A1 B1 A1 B2 B1 A1 A1 B2 A2 B1 B1 A2 B2 B2 A1 B2 A1 B2 A1 B2 B2 A1 A1 A1 B2 A2 B1 B2 B1 A2 A1 B2 A1 B2 B2 A1 B2 A1 A2 B1 B1 A2 A1
84.0606 103.2428 128.2006 128.5509 165.7681 200.5049 200.9571 216.5089 251.3294 283.4961 323.9574 352.7649 357.0154 367.3943 443.0147 525.9558 540.4284 561.3335 588.9529 688.0848 729.5574 821.9191 845.7277 887.6289 1014.7537 1023.0117 1038.4989 1042.9516 1047.5653 1067.0520 1071.1199 1071.3350 1104.3573 1219.2187 1274.8221 1324.7388 1341.2491 1413.2391 1426.2567 1433.2715 1435.9367 1451.3961 1496.1981 1496.2998 1503.1126 1503.5450 1523.2487 1526.8543 1527.1415 1534.9278 1540.1443 1627.1472 1680.7028 3064.3835 3064.8542 3075.6026 3076.1546 3144.6064 3144.7614 3151.7089 3151.8504 3169.0695
Calculated Intensity IR
Raman 0.1061 0.0153 0.5684 0.3089 0.0019 0.1457 0.8059 0.3855 3.3086 1.4098 0.2397 0.5065 3.0892 2.5438 5.6083 26.0735 0.7185 0.0585 0.1737 3.3986 2.0383 9.5339 0.1173 0.4110 3.4933 4.3553 0.0204 2.6121 0.3034 1.0970 0.0047 0.0126 1.1370 2.7040 1.2108 22.4944 6.0218 0.4943 15.6473 0.1550 27.0137 2.9251 7.8481 2.2942 18.4107 3.9746 1.0874 10.4071 0.6247 4.6761 0.2666 25.6044 30.4701 20.3204 366.2606 18.5560 335.8467 150.9507 1.4079 77.6739 26.6873 103.1145
IR
EP
AC C
Raman 67 110
209
252 297 352
441
TE D
0.0104 0.0000 1.2566 0.0000 4.2878 0.0000 0.0000 0.2594 2.1505 1.2857 0.1617 0.2929 0.0000 0.0010 0.0441 3.4579 1.8892 0.6771 0.0000 0.8123 0.5436 24.3407 0.0227 9.4274 21.9110 21.6908 7.1753 0.0000 3.8804 0.5863 0.0000 1.9658 1.2371 9.3070 0.8211 5.7667 2.0075 0.1870 0.4397 1.9650 2.4761 8.7200 2.4685 0.1837 0.0000 31.6382 4.3025 0.3151 0.0000 37.1130 37.7712 14.7772 5.0846 52.0728 20.9083 33.0369 8.0217 0.0000 29.4766 12.9848 0.0000 31.5998
Experimental frequencies (cm_1)
Assignments
SC
Sym.
CH3 twist Cm-H Car-Br, Car-Hand ring wagging Cm-H ,Car-H and ring rocking Cm-H and ring rocking Cm-H stretching and ring breathing Cm-H and ring rocking Cm-H ,Car-Br and ring rocking Cm-H, ring rocking Car-Br stretching, Ring breathing Cm-H Car-H and ring Rocking Car-Br stretching,CH3 rocking and ring breathing Cm-H Rocking, ring breathing Cm-H twisting, ring bending Car-Br stretching, Car-H Rocking, ring breathing Cm-H, Car-H and ring wagging Cm-H and ring breathing Cm-H Car-Hand ring wagging Cm-H, Car-H and ring rocking Cm-H and ring wagging Cm-H and ring breathing Cm-H,Car-H and ring rocking Car-Br , Car-H stretching, Cm-H and ring wagging Cm-H ,Car-H rocking and ring stretching Cm-H twisting ,Car-H rocking Cm-H and Car-H twisting, ring breathing CH3and ring wagging Cm-H ,Car-H and ring rocking Cm-H scissors and Ring bending Cm-H, Car-Hand Ring rocking Cm-H ,Car-H and ring wagging Cm-H ,Car-H and ring wagging Cm-H Car-Hand ring wagging Cm-H, Car-Hand Ring rocking CH3 rockine, Ring ip deformation Car-H bending Ring stretching Ring breathing Cm-H,Car-H rocking ,Ring ip deformation Cm-H ,Car-H wagging,Ring ip deformation CH3 umbrella deformation CH3 umbrella deformation , Ring rocking CH3 umbrella deformation ,Car-H, Ring rocking CH3 umbrella deformation,Car-H and ring wagging Cm-H rocking, Car-H ip bend, ring deformation Cm-H wagging Car-H bending Cm-H wagging CH3 umbrella defor,Car-H ip bend,Ring wagging Cm-H rocking Cm-H rocking CH3 umbrella deformation CH3 umbrella deformation, Car-H, Ring rocking CH3 umbrella deformation,Ring stretching Car-H ip bending, Ring stretching Cm-H stretching Cm-H stretching Cm-H stretching Cm-H stretching Cm-H twisting Cm-H twisting Cm-H twisting Cm-H twisting Cm-H stretching
M AN U
No
RI PT
In different layers
796
674 798
874 984 1020
1177 1270 1385 1390
1456 1458 1472
1542
1444
1545 1604
1655
2922
2921 2947
63 64 65 66
B2 B2 A1 A1
47.7201 ACCEPTED MANUSCRIPT
3169.1403 3197.8002 3198.1098 3203.8991
2.6707 27.2286 5.6922 23.2356
0.1135
50.8362 95.5097
Cm-H stretching Cm-H stretching Cm-H stretching Car-H stretching
Table 6 The charges of the atoms determined from natural bond orbital analysis (NBO) by PW1PW91/DGDZVP method MPW1PW91⁄DGDZVP Mulliken
EP
TE D
M AN U
SC
RI PT
0.040924 0.100922 0.149379 -0.503859 0.149379 0.100922 0.219007 -0.755686 0.254228 0.251938 0.251938 -0.755686 0.251938 0.251938 0.254228 -0.762233 0.237536 0.237536 0.242120 -0.762233 0.237536 0.237536 0.242120 -0.171431
AC C
Atoms C C C C C C H C H H H C H H H C H H H C H H H Br
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 2.View of a molecular layer of bromodurene projected in the plane (100) at
TE D
293K. Molecular stacking in the same layer is provided by distance C9··· C7.
Fig. 1.The molecular structure of bromodurene, with atom numbering. The
AC C
EP
displacement ellipsoids are drawn at the 50% probability level.
Fig. 3.View of interactions between parallel molecules of different layers in the crystal structure of C10H13Br. (Codes of symmetry: i) x, y, z; ii) 1 + xy, z. The molecular stacking in different layers is ensured by the distance C10··· C2 (3,732 Å, rc= 1,70 Å).
RI PT
ACCEPTED MANUSCRIPT
Fig. 5. Correlation graphic of calculated and experimental molecular bond
TE D
M AN U
SC
lengths of bromodurene compound.
Fig. 4. Molecular conformation of bromodurene (C2v symmetry) obtained from
AC C
EP
the calculation of the DFT: a) B3LYP / DGDZVP; b) MPW1PW91 / DGDZVP.
Fig. 6. Correlation graphic of calculated and experimental molecular bond angles of bromodurene compound.
RI PT
ACCEPTED MANUSCRIPT
Fig. 7. Experimental and MPW1PW91 / DGDZVP IR spectra of
Fig. 8. Experimental and MPW1PW91 / DGDZVP Raman spectra of Bromodurene.
M AN U
SC
Bromodurene.
(b) The total electron density mapped with electrostatic potential of bromodurene.
AC C
EP
TE D
Fig. 9. (a) The contour map of electrostatic potential of the total density
Fig. 10. HOMO and LUMO plot of bromodurene.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT High lights
EP
TE D
M AN U
SC
RI PT
The compound bromodurene was synthesized from durene. X-ray diffraction was applied to solve molecular structure. Spectral studies using IR, Raman spectroscopy was carry out. The DFT calculation of compound and MEP were examined. The DFT theoretical results were compared with the experimental results.
AC C