O R I G I N A L P A P E R
Synthesis, Crystal Structure, Spectroscopic and Electronic
Properties of
(E)-Trans-2-(2-(Biphenyl-4-
ylmethylene)Hydrazinyl)-4-(3-Methyl-3-Phenylcyclobutyl)Thiazole
C¸ ig˘dem Yu¨ksektepe•Nezihe C¸ alis¸kan•
Ibrahim Yilmaz•Alaaddin C¸ ukurovali
Received: 18 November 2009 / Accepted: 13 May 2010 / Published online: 26 May 2010 Ó Springer Science+Business Media, LLC 2010
Abstract A new compound of (C27H25N3S) has been
synthesized and characterized by1H NMR,13C NMR, IR, UV-Visible spectroscopy, and single crystal X-ray dif-fraction. The compound crystallizes in the monoclinic space group P21/c and crystals of (I) were found
approxi-mately 0.5:0.5 ratio to be twinned. The crystal structure is stabilized by N–HN inter molecular hydrogen bonding. In addition to the molecular geometry and dimeric structure from X-ray experiment, the optimized molecular geometry for monomer and dimer, vibrational frequencies, atomic charges distribution, and total energies of the title com-pound in the ground state have been calculated using ab initio method. Density Functional Theory (B3LYP) and Hartree-Fock (HF) methods with basis sets 6-31G(d, p) and 3-21G were used in the calculations. Calculated frequen-cies are in good agreement with the corresponding exper-imental data. UV-Vis absorption spectra of the compound have been ascribed to their corresponding molecular structure and electrons orbital transitions.
Keywords Hydrazine Single crystal ab initio calculations
Introduction
Schiff bases constitute an interesting class of chelating agents, capable of coordination with one or more metal ions to form mononuclear as well as polynuclear metal complexes [1, 2]. Some of these applications could be found in analytical chemistry and serve as biochemical models [3, 4]. Most Schiff bases have antibacterial, anti-cancer, anti-inflammatory and antitoxic activities and the sulfur-containing Schiff bases are particularly effective [5]. The aim of this work is to describe and investigate molecular and crystal structure of the new synthesize hydrazine derivative by a complex of the physical and chemical methods including IR- and UV-spectroscopy and X-ray single-crystal analysis and ab initio quantum chem-ical calculations of with formula C27H25N3S. IR
spectros-copy and Homo–Lumo energy gap are usually considered as important experimental and theoretical methods for chemists and physicist. In this paper, we report here the crystal structure with the formula, C27H25N3S, (I), the
molecular geometry for monomer and dimer, vibrational spectra and frontier molecular orbital properties, the Mul-liken charge distribution of the atoms of this compound have been reported by using ab initio calculations as Har-tree-Fock and Density Functional Theory (DFT/B3LYP) with 6-31G (d, p) and 3-21G basis sets.
Result and Discussion
X-Ray Crystallography
The data collection was performed at 293 K on a Stoe-IPDS-2 diffractometer equipped with a graphite monochromated Mo-Karadiation (k = 0.71073 A˚´ ). The structure was solved
C¸ . Yu¨ksektepe (&) N. C¸alis¸kan
Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayis University, 55139 Kurupelit, Samsun, Turkey e-mail: yuksekc@yahoo.com
I. Yilmaz
Department of Chemistry, Faculty of Science,
Karamanoglu Mehmetbey University, 70100 Karaman, Turkey A. C¸ ukurovali
Department of Chemistry, Faculty of Science, Firat University, 23119 Elazig˘, Turkey DOI 10.1007/s10870-010-9793-8
by direct methods using SHELXS-97 and refined by a full-matrix least-squares procedure using the program SHELXL-97 [6]. All non-hydrogen atoms were easily found from the difference Fourier map and refined anisotropically. All hydrogen atoms were included using a riding model and refined isotropically with C–H = 0.93 - 0.97 A˚ and N–H = 0.86 A˚ . Uiso(H) = 1.2Ueq(C, N), Uiso(H) = 1.5Ueq
(for methyl group).
DFT and HF Calculations
Starting geometries of compound (1) were taken from X-ray refinement data. The molecular structures of the title compound (C27H25N3S) in the ground state (in vacuo) are
optimized by Hartree-Fock (HF) and Density Functional Theory (DFT) methods to include correlation corrections with the 6-31G(d, p) and 3-21G basis sets. Furthermore, the geometry of two molecules linked by N–HN hydrogen bonding were taken from the experimental X-ray data and a full geometry optimization on the molecules named as a dimer was carried out with the DFT method by a B3LYP/3-21G basis set. In DFT calculation, hybrid functional are also used, the Becke’s three-parameter functional (B3) [7] which defines the exchange functional as the linear com-bination of Hartree-Fock, local and gradient-corrected exchange terms. The B3 hybrid functional was used in combination with the correlation functionals of Lee, Yang and Parr [8]. Two sets of vibrational frequencies, Mulliken charges and LUMO–HOMO energy differences for these species are calculated with these methods. All the calcu-lations are performed by using Gauss-View molecular visualization program [9] and GAUSSIAN-03 program package on personal computer [10].
Details of crystal parameters, data collection, structure solution and refinement are given in Table1. Selected bond distances and angles for X-ray, DFT and HF models are listed in Table2. Hydrogen bonds geometries are described in Table3. The calculated IR frequencies with the experi-mental data of (1) are compared in Table4. Mulliken charges for the compound (1) are listed in Table5and energies of frontier (HOMO, LUMO) orbitals in (1) are listed in Table6. Chemical diagram of (1) is introduced in Scheme1. ORTEP drawing diagram of the molecular structure is shown in Fig.1. Packing diagram with hydrogen bonding interaction is presented in Fig.2, Plots of the compounds with monomer and dimer in Fig.3a, b, The FT-IR spectrum of the title compound is shown in Fig.4. The frontier orbitals of monomer and dimer with its energy are plotted in Fig.5a, b.
Description of the Crystal Structure
The compound (I) crystallizes in the monoclinic, space group P21/c with unit cell parameters a = 17.201 A˚ ,
b = 5.873 A˚ , c = 24.791 A˚, b = 115.618. The title com-pound contains thiazole, hydrazine, three phenyls and cylobutane moieties. The crystal structure with the formula, C27H25N3S, (I) shown in Fig.1. The central five-member
thiazole ring is essentially planar, to within 0.0041 A˚ . The dihedral angles between the phenyl rings (C1 through C6), (C16 through C21), (C22 through C27), cyclobutane ring and thiazole ring are equal to 77.79(27)°, 14.52(44)°, 20.21(42)°, 53.71(30)°, respectively. As shown in Table2, in thiazole ring, it can be said that the C12–N1, S1–C13 and S1–C14 bond distances of 1.414(7), 1.709(7), 1.729(6) A˚ are showing the values of single bond character and it is worth noting that the C14–N1 and C12–C13 bond distance values of 1.296(7) A˚ and 1.350(8) A˚ are falling in to the C=N and C=C double bond distance region.
In structure of this compound, the thiazole and phenyl ring (C16 through C21) are linked by hydrazine group and the NH–N=CH–C fragment is strictly planar, N2–N3= C15–C16 torsion angle being -175.0(5)°. In hydrazine group, it can be said that the observed C15–N3 bond dis-tance of 1.255(7) A˚ is falling in to the C=N double bond distance region also N2–N3 and N2–C14 bond distances of 1.366(6) and 1.369(7) A˚ are showing the values of single Table 1 Crystallographic data of (1)
Empirical formula C27 H25 N3 S
Molecular weight 423.57
Temperature T (K) 296
Wavelength (A˚ ) 0.71073
Crystal system Monoclinic
Crystal size (mm3) 0.650 9 0.343 9 0.040 Space group P21/c a (A˚ ) 17.201 b (A˚ ) 5.873 c (A˚ ) 24.791 a (°) 90 b (°) 115.61 c (°) 90 Volume V (A˚3) 2258.3 Z 4 Tmin, Tmaks 0.9325, 0.9919 Calculated density (Mg m-3) 1.246 h range (8) 1.23–27.22 Index ranges h = -21 ? 21, k = -7 ? 7, l = -29 ? 29 Measured reflections 14917 Independent reflections 2658 Observed reflections (I [ 2r) 1119 Goodness-of-fit on F 2 0.95 R1 indice (I [ 2r) 0.078 wR2 indice (I [ 2r) 0.163
bond character. The steric interaction between the sub-stituent groups on the cyclobutane ring means that this ring deviates significantly from planarity. In this paper, the
C8/C9/C10 plane forms a dihedral angle of 18.58(56)° with the C10/C7/C8 plane.
In the crystal packing, the molecules are linked head to head by N–HN hydrogen bonding. In this hydrogen bonding the atoms N2 at (x, y, z) and (-x, y - 1/2, -z) acts as a donor to atoms N1 at (-x, 1 - y, -z) and (x, 1/2 - y, 1/2 ? z) generating a centrosymmetric R22(8) rings centred
at (0, 1/2, 0) and (0, 0, 1/2). The R22(8) rings formed by
hydrogen bonds are centred at [1, 0, n] and [1, 1/2, n ? 1/2] Table 3 Hydrogen bond interaction of (1) (A˚ , 8)
Hydrogen bond(A˚ , °) D–H HA DA D–HA
N2–H2AN1 0.86 2.31 3.090(7) 151
Symmetry code: -x, 1 - y, -z
Table 2 Selected geometrical parameters for X-ray structure, DFT and HF models Experimental Monomer B3LYP/3-21G Monomer B3LYP/6-31G** Monomer HF/6-31G** Dimer B3LYP/3-21G Bond lengths (A˚ ) N1–C14 1.296(7) 1.296 1.302 1.277 1.314 N1–C12 1.414(7) 1.412 1.389 1.387 1.415 N2–C14 1.369(7) 1.365 1.373 1.361 1.349 N2–N3 1.366(6) 1.383 1.346 1.348 1.396 N3–C15 1.255(7) 1.294 1.289 1.256 1.294 S1–C14 1.729(6) 1.837 1.758 1.739 1.834 S1–C13 1.709(7) 1.819 1.752 1.746 1.819 C1–C7 1.469(10) 1.515 1.517 1.518 1.515 C9–C12 1.495(9) 1.492 1.497 1.496 1.497 C12–C13 1.350(8) 1.355 1.363 1.339 1.352 C15–C16 1.455(8) 1.459 1.459 1.473 1.460 C19–C22 1.466(9) 1.486 1.483 1.490 1.486 Bond angles (°) C12–N1–C14 108.8(5) 111.6 110.3 110.7 112.1 N1–C14–N2 124.7(5) 124.4 122.3 122.0 124.9 C14–N2–N3 113.9(5) 119.2 121.2 119.1 116.2 N2–N3–C15 119.6(5) 118.1 118.2 118.5 117.5 N3–C15–C16 121.1(6) 121.4 122.2 122.3 121.1 C9–C12–N1 119.5(5) 117.4 117.8 117.1 117.9 N1–C12–C13 114.8(6) 115.8 115.3 115.4 115.3 C13–S1–C14 88.5(3) 85.3 87.3 87.6 86.1 N1–C14–S1 116.5(5) 115.8 116.2 116.0 114.6 C12–C13–S1 111.3(5) 111.5 110.8 110.3 112.0 C8–C9–C12 116.5(6) 116.2 118.3 118.1 117.8 C10–C9–C12 117.5(6) 118.9 120.2 120.3 118.2 C9–C12–C13 125.7(5) 126.9 126.9 127.5 125.6 Torsion angles (°) C9–C12–N1–C14 177.9(6) 179.3 179.6 179.7 178.5 C12–N1–C14–N2 -177.5(5) -179.7 -179.9 -178.4 -177.1 N1–C14–N2–N3 -176.7(5) -179.6 -179.5 -171.7 -175.7 C14–N2–N3–C15 176.3(6) 179.6 179.6 172.5 177.5 N2–N3–C15–C16 -175.0(5) -179.9 -179.9 -179.2 -179.8 N3–C15–C16–C17 -7.4(10) 0.2 0.1 0.1 0.4 N3–C15–C16–C21 171.3(7) 179.7 179.9 179.9 179.6 C13–S1–C14–N2 178.2(5) 179.8 179.9 178.4 -178.0 S1–C13–C12–C9 -177.7(6) -179.3 -179.7 -.179.4 -180.0
(n is zero or integer). As a result of these interactions formed hydrogen bonded dimer of graph set motif R2
2
(8) ring at (n, m ? 1/2, k) and (n, m, k ? 1/2) by similarly N–HN hydrogen bonding [11] (Table3, Fig.2) at (n, m, k), (where n, m and k are integer). These dimers are running along the a axis of the monoclinic cell. Beside of these dimers, the
C–Hp and p–p interactions are stabilize to crystal packing. Crystals of (I) were found approximately 0.5:0.5 ratio to be twinned, and the twinned cell can be obtained by the unit-cell transformation atwin vector = a vector, btwin vector = -b
vector, ctwinvector = -c vector, therefore the twinning axis,
which is two-fold, is along [100] direction. Table 4 Vibrational frequencies for X-ray structure, DFT and HF models
Frequencies Experimental B3LYP
6-31G** Monomer HF 6-31G** Monomer B3LYP 3-21G Monomer B3LYP 3-21G Dimer tstr(NH) 3155 3515 3824 3437 2699–2617 tstr(CH) thiazole 3120 3279 3444 3316 3318–3311 tstr(CH) sym aromatic 3056 3218–3202 3387–3364 3229–3210 3229–3210 tstr(CH) asym aromatic 3024 3200–3171 3359–3331 3205–3182 3209–3179 tstr(CH2) asym 2953 3127–3118 3272–3265 3159–3150 3159–3151 tstr(CH3) asym 2932 3111–3108 3250–3247 3113–3110 3108 tstr(CH2) sym 2909 3069–3060 3219–3208 3094/3086 3094–3083 tstr(CH) sym in cyclobutane 3024 055 3215 3089 3123/3073
tstr(CH) sym in schiff base 2858 3049 3242 3064 3119/3113
tstr(CH3) sym 2793 3035 3178 3043 3043 tstr(C=N) ? tstr(CC) 1602 1681 1914 1644 1643–1642 tstr(CC) 1599 1661–1634 1820–1778 1633 1633–1630 tstr(C=N) ? tstr(CN) 1572 1627 1775 1635 1615–1613 tstr(CC) 1537 1600 1750 1631–1608 1612–1608 tstr(C=C) 1487 1580 1762 1576–1573 1598–1587 trock(CH) 1467 1561–1533 1694–1658 1557 1575/1557 tsci(CH2) ? tsci(CH3) 1434 1515 1639 1561 1561/1519 tbend(CH3) 1406 1506–1504 1624–1623 1537 1554 tbend(CH) in plane 1360 1491–1487 1615 1547–1543 1548–1542 tbend(CH2) in plane 1317 1486 1610 1547 1539–1535 tbend(NH) ? tbend(CH) 1307 1474 1606 1469 1687/1530 trock(CH3) 1278 1419 1546 1454 1457–1456 trock(NH) ? trock(CH) 1265 1402–1384 1512/1556 1449 1679 trock(CH) in aromatic 1230 1366–1362 1468–1461 1395–1367 1502 tbreath(Ring) – 1349 – 1314–1307 1314–1298 twag(CH3) ? twag(CH2) 1196 1330 1457 1333/1265 1268 tbend(N=C–N) ? trock(CH) 1135 1320 1413 1285 1287/1398 tstr(CN) 1109 1297 – 1278 – ttwist(CH2) 1077 1266 1403–1365 1255–1251 1261 tsci(CH) in aromatic 1028 1214–1186 1344–1297 1243–1230 1450–1451 tstr(NN) 1006 1185 1251 1073 – trock(CH3) ? ttwist(CH2) ? 950 1181 1288 1192 1333–1331 tsci(CH) twag(CH) 918 1175 1125 1035 1000 tstr(CSC) 838 793 858 774 752
tbend(CH) out of plane 698 741–715 857 767 1032–1021
tbend(NH) out of plane 763 – – 623 1094–1090
Table 5 Mulliken charges for DFT and HF models Atoms Monomer B3LYP/6-31G** Monomer HF/6-31G** Dimer B3LYP/3-21G Monomer B3LYP/3-21G C1 0.12 0.01 0.06 0.06 C2 -0.12 -0.15 -0.20 -0.19 H2 0.08 0.15 0.18 0.18 C3 -0.09 -0.14 -0.18 -0.18 H3 0.08 0.15 0.18 0.18 C4 -0.09 -0.16 -0.19 -0.19 H4 0.08 0.14 0.18 0.18 C5 -0.09 -0.14 -0.18 -0.18 H5 0.08 0.14 0.18 0.18 C6 -0.12 -0.15 -0.19 -0.20 H6 0.08 0.14 0.18 0.18 C7 -0.03 -0.11 -0.18 -0.18 C8 -0.16 -0.18 -0.32 -0.30 H8A 0.09 0.12 0.18 0.19 H8B 0.10 0.13 0.21 0.21 C9 -0.13 -0.15 -0.31 -0.29 H9 0.11 0.14 0.21 0.21 C10 -0.18 -0.20 -0.31 -0.32 H10A 0.10 0.13 0.22 0.21 H10B 0.09 0.12 0.19 0.18 C11 -0.30 -0.29 -0.51 -0.50 H11A 0.10 0.11 0.18 0.18 H11B 0.11 0.12 0.19 0.18 H11C 0.10 0.12 0.20 0.19 C12 0.31 0.30 0.36 0.33 C13 -0.35 -0.44 -0.61 -0.60 H13 0.12 0.17 0.22 0.22 S1 0.23 0.28 0.53 0.51 N1 -0.51 -0.61 -0.64 -0.57 C14 0.34 0.43 0.34 0.31 N2 -0.25 -0.29 -0.31 -0.30 H2A 0.27 0.32 0.38 0.33 N3 -0.39 -0.52 -0.62 -0.57 C15 0.09 0.17 0.11 0.12 H15 0.07 0.13 0.21 0.18 C16 0.10 -0.06 -0.04 -0.04 C17 -0.12 -0.13 -0.17 -0.17 H17 0.11 0.19 0.22 0.22 C18 -0.12 -0.15 -0.18 -0.18 H18 0.09 0.16 0.19 0.19 C19 0.07 -0.01 -0.00 -0.00 C20 -0.12 -0.15 -0.19 -0.19 H20 0.09 0.16 0.19 0.19 C21 -0.14 -0.15 -0.21 -0.19 H21 0.08 0.15 0.20 0.18 C22 0.06 -0.01 -0.01 -0.01 C23 -0.11 -0.15 -0.19 -0.19
Eventually, when the observed some bond distances in the structure of this compound are compared with analogous bonds in related compounds, it can be said that the S–C bond distances are shorter than the accepted value for an S–C sp2 single bond with 1.76 A˚ [12], the C14–N1 double bond is shorter than the C=N double bond distance found in related
thiazole ring structure [13–16] also the C15–N3 double bond is shorter than the C=N bond distance found related hydrazine structures, i.e. 1.2810(19) A˚ in [17] and 1.272(2) A˚ in [18]. In addition to these, the value for the puckering of the cyclobu-tane ring of this structure is found to be differ than literature values being 29.03(13)° in [19] and 26.8(2)° in [20]. Geometry Optimization of (1)
In this work, we performed full geometry optimization of the title compound (see Fig.3a, b for monomer and dimer). For monomer and dimer, some selected geometric Table 5 continued Atoms Monomer B3LYP/6-31G** Monomer HF/6-31G** Dimer B3LYP/3-21G Monomer B3LYP/3-21G H23 0.09 0.16 0.19 0.19 C24 -0.09 -0.15 -0.18 -0.18 H24 0.09 0.15 0.19 0.19 C25 -0.08 -0.15 -0.18 -0.18 H25 0.09 0.15 0.19 0.19 C26 -0.09 -0.15 -0.18 -0.18 H26 0.09 0.15 0.19 0.19 C27 -0.11 -0.15 -0.19 -0.19 H27 0.09 0.15 0.19 0.19
Table 6 Energies molecular orbital for DFT and HF models
Energies B3LYP/6-31G** Monomer HF/6-31G** Monomer B3LYP/3-21G Monomer B3LYP/3-21G Dimer Homo (a.u.) -0.192 -0.279 -0.197 -0.195 Lumo (a.u.) -0.057 0.082 -0.057 -0.057
D (a. u.) (eV) 0.134 (3.657) 0.362 (9.828) 0.140 (3.809) 0.138 (3.757)
Total Energies (a.u.) -1606.370 -1597.855 -1597.719 -3195.482
Homo-1(a.u.) -0.227 -0.309 -0.231 -0.198
Homo-2(a.u.) -0.234 -0.316 -0.238 -0.232
Lumo?1 (a.u.) -0.009 0.136 -0.006 -0.056
Lumo?2(a.u.) -0.006 0.140 -0.004 -0.009
Fig. 1 ORTEP drawing of the basic crystallographic unit, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii N S CH N NH H3C Scheme 1
parameters experimentally obtained and theoretically cal-culated by B3LYP with 6-31G** and 3-21G and by HF with 6-31G** where ** is shown (d, p) as the basic set are listed in Table2. In present study, we have also compared with a dimer structure of compound using the density functional B3LYP theory with 3-21G basis set in Table2. These calculated geometric parameters generally give bond lengths which are slightly larger than the experimental values, due to the fact that the theoretical calculations
belong to isolated molecules in a gaseous phase and the experimental results belong to molecules in the solid state. It was found that the bond angles calculated by B3LYP methods are consisted with those by HF method. However the bond lengths calculated by HF method are little shorter than those obtained by B3LYP method. For example, the optimized bond lengths of N–C in thiazole and hydrazine groups fall in the range 1.256–1.387 A˚ for HF and 1.289– 1.412 A˚ for B3LYP method which are in good agreement with those of experimental bond lenghts [1.255(7)– 1.414(7) A˚ ]. Torsion angles in dimer provided by B3LYP/ 3-21G method are closer than an isolate structure in experimental values (Table2), as the molecule in dimer contains the intermolecular interactions.
The crystal structure exhibits N–HN intermolecular hydrogen bond as shown in Table3. N–HN bond lengths and angle were calculated theoretically for compared with experimental ones. N–H length is calculated 1.07 A˚ , NN length is calculated 2.801 A˚ and N–HN bond angle is calculated 1728. Compared to the experimental in Table3
and calculated in above values, N–H bond length (ca.) is longer than experimentally one. But NN bond length obtained by computational method shows good agreement with the experimental value.
FT-IR Spectra
Experimentally, the FT-IR spectrum of the title compound is shown in Fig.4. In order to investigate that intermo-lecular hydrogen bond influences on the vibrational fre-quencies, we have calculated the theoretical harmonic vibrational spectra of monomer and dimer molecules by using B3LYP and HF methods with 6-31G** and 3-21G basis set. Theoretical and experimental results of the title compound are shown in Table4. It is known that ab initio calculations systematically overestimate the vibrational wavenumbers and discrepancies. We noted that the experimental results belong to solid phase and theoretical calculations belong to gaseous phase. All the calculated spectra are in good agreement with the experimental data. All DFT methods are superior to HF method in terms of realistic reproduction of both band intensity distribution and general spectral features.
The characteristic tCH stretching vibrations of
hetero-aromatic structures are expected to appear in 3000– 3100 cm-1frequency ranges [21,22]. In the present study, tCH stretching vibrations of the title compound are
observed at 3120, 3056, 3024 and 2858 cm-1. Besides, the calculated band at 1467/1365/1230/1135, 1360, 1028/950, 918, 698 cm-1are attributed to four rocking, one bending, two scissorsing, one wag and one bending out of plane which are in good agreement with the calculated frequen-cies at for HF and B3LYP methods.
Fig. 2 A partial packing diagram for the compound, showing the N–HN interaction as broken lines. Hydrogen atoms not involved in hydrogen bonding have been omitted. [Symmetry code: -x, 1 - y, -z]
Fig. 3 a Gaussian03View drawing of the title compound with monomer. b Gaussian03View drawing of the title compound with dimer
As shown in Table4, experimentally determined vibrational bands of the compound were found to be sig-nificantly lower than calculated values, however, tNH
stretching vibrations are observed at 3155 and 2699– 2617 cm-1 and bending vibrations are observed at 1307 and 1687/1530 cm-1for experimental and theoretical (for dimer) values, respectively. Due to N–HN inter molec-ular hydrogen bonding, it can be said that experimental mNH
bending vibration is increasing while mNH strecthing
vibration is decreasing.
For the assignments of CH3 group frequencies, seven
fundemental vibrations can be associated to CH3groups.
Two stretching, one scissorsing, one bending, two rocking and one wag vibration mode designated the motion of the methyl group. The CH3antisymmetric stretching vibration
is established at 2932 cm-1 and the CH3 symmetric
stretching vibration is established at 2793 cm-1 in the spectra. In the present study various vibrations of CH3
group are summarized in Table4and are also supported by the literature [21,22].
The antisymmetric CH2stretching vibrations are
gener-ally observed in the region 3100–3000 cm-1, while the symmetric stretching vibrations are generally observed in the region 3000–2900 cm-1[23]. In the spectra, the CH2
anti-symmetric stretching vibration is established at 2953 cm-1, whereas CH2symmetric stretching vibration is established at
2909 cm-1, for HF method, the CH2 antisymmetric and
symmetric stretching vibrations are calculated at 3272– 3265 cm-1and 3219–3208 cm-1, respectively, for B3LYP/ 6-31G** method, the CH2 antisymmetric and symmetric
stretching vibrations are calculated at 3127–3118 cm-1and 3069–3060 cm-1, respectively, for B3LYP/3-21G method,
the CH2antisymmetric and symmetric stretching vibrations
are calculated at 3159–3150 cm-1 and 3094–3086 cm-1, respectively, for B3LYP/3-21G (dimer) method, the CH2
antisymmetric and symmetric stretching vibrations are cal-culated at 3159–3151 cm-1and 3094–3083 cm-1, respec-tively. The other vibrations bands are summarized in Table4.
The identification of C–N vibrations is a difficult task, since the mixing of vibrations is possible in this region. In this study, the C–N and C=N stretching vibrations are observed at 1572, 1109 and 1602, 1572 cm-1respectively, and it is calculated at 1175 and 1914, 1775 cm-1 for HF, and at 1627, 1297 cm-1and 1671, 1627 cm-1, for B3LYP/ 6-31G**, and at 1635, 1278 and 1644, 1635 cm-1 for B3LYP/3-21G, and at 1615, 1613 and 1643, 1642, 1615, 1613 cm-1 for B3LYP/3-21G (dimer) methods, respec-tively. The observed C–C stretching, N=C–N bending and C–S–C stretching vibrations are at 1602, 1599, 1537, 1135 and 838 cm-1, respectively. The theoretically calculated modes have been found to be consistent with the recorded spectral values. The observed frequency for the C–S–C stretching vibration is found to be higher in calculation, while the other calculated vibrations are some higher than observed values.
The Mulliken charge distribution of the atoms in the compound is listed in Table5. As can be seen from Table5, the negative charges on the nitrogen atoms are significantly bigger than the other atoms, but the positive charges are expected to be localized on the protonated nitrogen atoms. However, the calculations show that the positive charges are on hydrogens bound to the N2 atom is found to be much bigger than those of other hydrogen
3155.86, 49.57 3056.79, 45.12 3024.00, 47.34 2953.73, 39.52 2932.64, 40.81 2858.30, 45.17 2793.54, 51.05 1602.31, 54.56 1571.91, 20.59 1537.01, 46.24 1487.73, 44.46 1434.75, 46.74 1360.27, 48.51 1406.13, 56.49 1278.56, 58.24 1265.26, 58.69 1230.61, 63.59 1196.48, 69.16 1135 .23, 48.61 1109. 58, 49.28 1006.39, 56.35 918.08, 66.90 871.88, 71.07 838.18, 61.62 763.97, 34.05 698.04, 37.67 720.89, 56.24 542. 403, 69.2 489.58, 73.80 500 1000 1500 2000 2500 3000 3500 4000 20 30 40 50 60 Wavenumbers % Transmittance 80 70
atoms in the title compound, indicating that the positive charges are delocalized between the nitrogen and hydrogen atoms.
Absorption Spectra
The calculations indicate that the compound and the dimeric structure have 112 and 224 occupied molecular orbitals (MOs), respectively. The highest occupied molecular orbital (HOMO) energies, the lowest unoccupied molecular orbital (LUMO) energies, the energy gap and total energies for mentioned molecules in above have calculated and given in Table6.
An electronic system with a larger HOMO–LUMO gap should be less reactive than one having a smaller gap [24].
The HOMO–LUMO gap values of the molecules are between 3.657, 9.828 [If the electron correlations had not been included, the energy difference HOMO–LUMO would be nearly 10 eV], 3.809 and 3.757 eV for B3LYP/6-31G**, HF, B3LYP/3-21G (monomer and dimer) methods, respectively, as seem in Table6.
The UV-Vis absorption spectra of the title compound were recorded in the CHCl3 solutions. The Compound
exhibits absorption peaks in the UV-Visible region. The absorption peaks are observed at 348, 270 nm for the title compound. It can be seem that these peaks equal to n ? p* and p ? p* transitions. The frontier molecular orbitals of the compound and dimeric structure have been investigated basing on the B3LYP/3-21G calculations. 3D plots of the
HOMO-2, HOMO-1, HOMO, LUMO, LUMO?1,
LUMO?2 and the corresponding energy levels for the title compound and the dimeric form are shown in Fig.5a and b, respectively. The theoretically electronic transfer (ET) peaks for the compound B3LYP/6-31G** and B3LYP/3-21G basis sets are at 339, 269 and 326, 262 nm to corre-spond to the UV-Vis spectral absorption peaks, and the corresponding electronic transfers happened between HOMO and LUMO, HOMO-1 and LUMO, respectively. The same UV-Vis spectral fact as the compound has been investigated in the dimeric form with 3-21G basis set, the theoretically calculated ET peaks are at 331, 324 nm to correspond to the experimental absorption ones. Basing on the investigation on the frontier molecular orbitals (FMOs) energy levels of dimer, we can find that the corresponding electronic transfers happened between HOMO and LUMO (or HOMO and LUMO?1), HOMO and LUMO?2, respectively. The bigger theoretical absorption wave-lengths of the compound have slight blue-shifts comparing with the corresponding experimental ones. Besides, the deviation of energy gap for monomer and dimer form with the same basis set may be due to the intermolecular interactions have a significant influence in decreasing the HOMO–LUMO gaps in solids [25,26].
Natural population analysis indicates that the electronic transitions are mainly derived from the contributions of bands p ? p* as reported literature [27]. As shown from Fig.5, the electron clouds of the HOMOs and HOMO-1s are localized on the thiazole and phenyl rings connected with hydrazine bridge. The HOMOs and HOMO-1s for monomer and dimer have approximately similar shapes and seem to be the p- bonding type orbital, but HOMO-2s are different shapes. The electronic distribution for monomer and dimer is localized similar regions. The LUMOs, LUMO?1s and LUMO?2s for monomer and dimer have same figures. For monomer and dimer, LUMOs, LUMO?1s and LUMO?2s orbitals are found mainly localized on the N atom and phenyl ring. In all cases, LUMOs are p*-anti-bonding orbitals.
LUMO+2: -0.100 eV LUMO+2: -0.237 eV LUMO+1: -0.170 eV LUMO+1: -1.527 eV LUMO: -1.560 eV LUMO: -1.552 eV HOMO: -5.369 eV HOMO: -5.309 eV HOMO-1: -6.295 eV HOMO-1: -5.391 eV HOMO-2: -6.472 eV HOMO-2: -6.328 eV a b
Fig. 5 a Plots of the frontier orbitals of the compound with monomer. b Plots of the frontier orbitals of the compound with dimer
Experimental Section
Measurement
IR spectra were recorded on an ATI Unicam-Mattson 1000 FT-IR spectrophotometer using KBr pellets.1H NMR and
13C NMR spectra were obtained by using a Bruker
300 MHz spectrometer. The UV spectra of the compound were performed on a Schimadzu UV-1700 spectrometer in CHCl3solvent.
Synthesis of Compound (E)-Trans-2-(2-(Biphenyl-4-
ylmethylene)Hydrazinyl)-4-(3-Methyl-3-Phenylcyclobutyl)Thiazole
The compound was synthesized as in Scheme1 by the following procedure. To a solution of 4-biphenyl-carbox-yaldehyde (1.8222 g, 10 mmol) in 50 mL of ethanol, thi-osemicarbazide (0.9113 g, 10 mmol) was added portions. Subsequently, a solution of 1-methyl-1-phenyl-3-(2-chloro-1-oxoethyl) cyclobutane (2.2271 g, 10 mmol) in 20 mL of absolute ethanol was added. After the addition of the a-haloketone, the temperature was raised to 323–328 K and kept at this temperature for about 2 h. The solution was cooled to room temperature and then made alkaline with an aqueous solution of NH3 (5%), and yellow precipitate
separated by suction. washed with aqueous NH3solution
several times and dried in air. Suitable single crystals for crystal structure determination were obtained by slow evaporation of its ethanol solution. The compound was obtained in a yield of 74%, melting point: 466 K. Char-acteristic 1H NMR shifts (CDCl3, d, ppm): 1.53 (s, 3H, –CH3on cyclobutane), 2.53 (d, j = 9.16 Hz, 4H, –CH2– in cyclobutane), 3.67 (q, j = 8.8 Hz, 1H, [C–H in cyclobu-tane), 6.25 (s, 1H, = CH-S in thiazole), 7.13–7.77 (m, 14H, aromatics), 7.82 (s, 1H, -N=CH–, azomethine), 9.58 (s, 1H, –NH–). Characteristic13C NMR shifts (CDCl3, d, ppm): 168.73, 156.34, 152.46, 142.40, 141.24, 140.66, 133.40, 129.08, 128.44, 127.85, 127.60, 127.36, 127.23, 125.54, 124.96, 102.38, 40.52, 39.09, 31.06, 30.33. Conclusions
The crystal structure of C27H25N3S, (I), is investigated with
X-ray diffraction and observed values as bond lengths and angles are compared with the calculated values. The the-oretical vibrational spectrum assignments of C27H25N3S,
(I), monomer and dimer have been calculated and the experimental vibrational spectrum assignments of (I) are compared with theoretical results, besides of these, the optimized molecular geometry, frontier molecular orbital properties and the Mulliken charge distribution of the
atoms of this compound have been calculated by using ab initio calculations as Hartree-Fock and Density Func-tional Theory (DFT/B3LYP) with 6-31G** and 3-21G basis sets. As a consequence, all the calculated spectra, bond lengths and angles of this structure are in good agreement with the experimental data.
Supplementary Data
Crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic Data Cen-tre, CCDC No 734726 Copies of this information may be obtained free of charge from the Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: ?44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
Acknowledgements The authors wish to acknowledge the Faculty of Arts and Sciences, Ondokuz Mayis University, Turkey, for the use of the STOE IPDS-II diffractometer (purchased under grant F.279 of the University Research Fund).
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