КООРДИНАЦИОННАЯ ХИМИЯ, 2015, том 41, № 9, с. 552-558
УДК 541.49
SYNTHESIS AND X-RAY STRUCTURES OF DI- AND MONO-NUCLEAR OXOVANADIUM(V) COMPLEXES DERIVED FROM AROYLHYDRAZONES
© 2015 X. Z. Zhang1, T. Wang2, X. F. Chen1, J. Li1, H. H. Li2, Z. L. You2, *, and H. L. Zhu1, *
1School of Life Sciences, Shandong University of Technology, ZiBo, 255049 P.R. China 2Department of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029 P.R. China *E-mail:youzhonglu@126.com; hailiang_zhu@163.com Received February 23, 2015
A new methanolato-bridged dinuclear oxovanadium(V) complex [VO(L)(OMe)]2 (I) derived from N'-(2-hy-droxy-5-methylbenzylidene)-2-methylbenzohydrazide (H2L) and a new mononuclear oxovanadium(V) complex [VO(L')(OMe)(MeOH)] (II) derived from 3-chloro-N'-(2-hydroxy-3-methylbenzylidene)benzo-hydrazide (H2L') were prepared and characterized by infrared spectra and single crystal X-ray determination (CIF files CCDC nos. 974793 (I) and 974792 (II)). Complex I crystallizes as triclinic space group P1 with unit cell dimensions a = 8.5063(4), b = 9.5367(4), c = 11.2445(5) Â, a = 71.740(1)°, в = 72.341(1)°, у = = 74.509(1)°, V = 810.37(6) Â3, Z = 1, R1 = 0.0527, wR2 = 0.1316, S = 0.969. The complex possesses a crys-tallographic inversion center symmetry between two V atoms. Complex II crystallizes as triclinic space group P1 with unit cell dimensions a = 7.4257(3), b = 9.9475(4), c = 13.1021(5) Â, a = 71.954(1)°, в = 85.657(1)°,
Y = 84.127(1)°, V= 914.38(6) Â3, Z = 2, R1 = 0.0365, wR2 = 0.0957, S = 1.039. The tridentate aroylhydrazone ligands coordinate to the V center through azomethine nitrogen, phenolate oxygen and enolate oxygen. The
V atoms in the complexes are in octahedral coordination. Crystal structures of the complexes are stabilized by hydrogen bonds and n---n interactions.
DOI: 10.7868/S0132344X1509011X
INTRODUCTION
Coordination chemistry of vanadium has attracted considerable attention due to its biochemical significance [1—3] as well as for the efficient catalytic properties in several organic synthesis procedures [4—7]. Aroylhydrazones are a kind of interesting ligand in coordination chemistry [8—10]. In recent years, a number of oxovanadium complexes with aroylhydrazones as ligands have been reported. During the search of literature, we found that most of the oxovanadium complexes with aroylhydrazone ligands are mononuclear, with solvent molecules or bidentate ligands completed the octahedral coordination [11—15]. Only a few examples are bridged by methanolate groups [16, 17]. Considering oxovanadium complexes with aroylhy-drazone ligands have been reported to possess interesting biological activities [18, 19] and catalytic properties [20, 21], exploration of the synthesis and their detailed structures seems to be of particular importance. In this paper, a new methanolato-bridged dinuclear oxovanadium(V) complex [VO(L)(OMe)]2 (I) and a new mononuclear oxovanadium(V) complex [VO(L')(OMe)(MeOH)] (II), where L and L' are the dianionic form of N'-(2-hydroxy-5-methylben-zylidene)-2-methylbenzohydrazide (H2L) 3-chloro-N'-(2-hydroxy-3-methylbenzylidene)benzohydrazide (H2L'), respectively, are presented.
EXPERIMENTAL
Materials and measurements. Commercially available 5-methylsalicylaldehyde, 3-methylsalicylaldehyde, 2-methylbenzohydrazide and 3-chlorobenzohy-drazide were purchased from Aldrich and used without further purification. [VO(Acac)2] was purchased from Shenyang Haizhongtian Chemical Company. Other solvents and reagents were made in China and used as obtained. C, H, and N elemental analyses were performed with a PerkinElmer elemental analyser. Infrared spectra were recorded on a Nicolet AVATAR 360 spectrometer as KBr pellets in the 4000—400 cm-1 region. Thermal stability analysis was performed on a PerkinElmer Pyris Diamond TG-DTA thermal analyses system.
Synthesis of H2L. 5-Methylsalicylaldehyde (1.0 mmol, 0.14 g) and 2-methylbenzohydrazide (1.0 mmol, 0.15 g) were dissolved in methanol (30 mL) with stirring. The mixture was stirred for about 30 min at room temperature to give colorless solution. The solution was left still in air to slow evaporate of most of the solvent, to give crystalline product of H2L. The product was isolated by filtration and washed with cold methanol. The yield was 87%.
Selected IR data (KBr; v, cm-1): 3237 (N-H), 1641 (C=O), 1616 (C=N).
For C16H16N2O2
anal. calcd., %: C, 71.62; H, 6.01; N, 10.44. Found, %: C, 71.53; H, 6.12; N, 10.55.
Synthesis of H2L'. 3-Methylsalicylaldehyde (1.0mmol, 0.14 g) and 3-chlorobenzohydrazide (1.0 mmol, 0.17 g) were dissolved in methanol (30 mL) with stirring. The mixture was stirred for about 30 min at room temperature to give colorless solution. The solution was left still in air to slow evaporate of most of the solvent, to give crystalline product of H2L. The product was isolated by filtration and washed with cold methanol. The yield was 81%.
Selected IR data (KBr; v, cm-1): 3228 (N-H), 1645 (C=O), 1613 (C=N).
For C15H13ClN2O2
anal. calcd., %: C, 62.40; H, 4.54; N, 9.70. Found, %: C, 62.23; H, 4.65; N, 9.82.
Synthesis of I. A methanolic solution (10 mL) of [VO(Acac)2] (0.1 mmol, 27.0 mg) was added to a methanolic solution (10 mL) of H2L (0.1 mmol, 26.8 mg) with stirring. The mixture was stirred for 30 min to give a deep brown solution. The resulting solution was allowed to stand in air for a few days. Brown block-shaped crystals suitable for X-ray single crystal analysis were formed at the bottom of the vessel. The isolated product was washed three times with cold methanol and dried in a vacuum over anhydrous CaCl2. The yield was 67%.
Selected IR data (KBr; v, cm-1): 1607 (C=N), 976 (V=O).
For C34H34N4O8V2
anal. calcd., %: C, 56.05; H, 4.70; N, 7.69. Found, %: C, 55.89; H, 4.77; N, 7.54.
Synthesis of II. A methanolic solution (10 mL) of [VO(Acac)2] (0.1 mmol, 27.0 mg) was added to a methanolic solution (10 mL) of H2L (0.1 mmol, 28.9 mg) with stirring. The mixture was stirred for 30 min to give a deep brown solution. The resulting solution was allowed to stand in air for a few days. Brown block-shaped crystals suitable for X-ray single crystal analysis were formed at the bottom of the vessel. The isolated product was washed three times with cold methanol and dried in a vacuum over anhydrous CaCl2. The yield was 55%.
Selected IR data (KBr, v, cm-1): 1608 (C=N), 974 (V=O).
For C34H34N4O8V2
anal. calcd., %: C, 49.00; H, 4.35; N, 6.72.
Found, %: C, 48.82; H, 4.51; N, 6.63.
X-ray diffraction. Diffraction intensities for the complexes I, II were collected at 298(2) K using a Bruker D8 VENTURE PHOTON diffractometer with MoZa radiation (X = 0.71073 Â). The collected data were reduced using SAINT [22], and multi-scan absorption corrections were performed using SADABS [23]. Structures of the complexes were solved by direct method and refined against F2 by full-matrix least-squares methods using SHELXTL [24]. All of the non-hydrogen atoms were refined anisotropically. The methanol H atom in complex II was located from a difference Fourier map and refined isotropically with N-H distance restrained to 0.90 Â. The remaining H atoms were placed in idealized positions and constrained to ride on their parent atoms. Crystallograph-ic data for the complex are summarized in Table 1. Selected bond lengths and angles are given in Table 2.
Supplementary material has been deposited with the Cambridge Crystallographic Data Centre (CCDC nos. 974793 (I) and 974792 (II); deposit@ccdc. cam.ac.uk or http://www.ccdc.cam.ac.uk).
RESULTS AND DISCUSSION
The aroylhydrazone compounds were readily prepared by reaction of 5-methylsalicylaldehyde with 2-methylbenzohydrazide, and 3-methylsalicylalde-hyde with 3-chlorobenzohydrazide in methanol. Replacement of two acetylacetonate ligands in [VO(Acac)2] by aroylhydrazone ligands resulted in the oxovanadium(V) complexes. The dinegative aroylhy-drazone ligands coordinated to the V atoms through the azomethine nitrogen, phenolate oxygen and eno-late oxygen. The complexes are soluble in methanol, ethanol and acetonitrile. Molar conductance of complexes I and II at concentration of 10-4 mol/L are 45 and 30 fi-1 cm2 mol-1, indicating their non-electrolyte nature [25].
Molecular structure and atom numbering scheme of complex I are shown in Fig. 1a. The complex possesses a crystallographic inversion center symmetry between two V atoms. The V atom in the complex is in octahedral coordination, with the azomethine N, phenolate O, and enolate O atoms of the aroylhydrazone ligand, as well as one methanolate O atom defining the equatorial plane, and with the other methano-late O atom and an oxo O atom locating at the axial positions. The V atoms deviate from the least-squares planes defined by the equatorial atoms by 0.333(1) Â. Coordinate bond lengths in complex I are similar to those observed in vanadium complexes with aroylhy-
Table 1. Crystallographic and experimental data for complexes I and II
Parameter Value
I II
Fw 728.5 416.7
Crystal shape/color Block/brown Block/brown
Crystal size, mm 0.17 x 0.15 x 0.15 0.13 x 0.10 x 0.10
Crystal system Triclinic Triclinic
Space group P1 p1
a, Â 8.5063(4) 7.4257(3)
b, Â 9.5367(4) 9.9475(4)
c, Â 11.2445(5) 13.1021(5)
a, deg 71.740(1) 71.954(1)
ß, deg 72.341(1) 85.657(1)
Y, deg 74.509(1) 84.127(1)
V, Â3 810.37(6) 914.38(6)
Z 1 2
^(MoÄ"a), mm-1 0.636 0.719
p, g cm-3 1.493 1.514
Reflections/parameters 2912/220 3706/241
Independent reflections 2701 3453
Restraints 0 1
Index ranges h, k, l -9 < h < 10 -11 < k < 10 -13 < l < 13 -9 < h < 8 -12 < k < 12 -16 < l < 14
F(000) 376 428
TmvcJ Tmax 0.8996/0.9107 0.9123/0.9316
Goodness of fit on F2 0.969 1.039
R1, wR2 (I> 2a(I))* 0.0527, 0.1316 0.0365, 0.0957
R1, wR2 (all data)* 0.0561, 0.1350 0.0392, 0.0983
* R1 = ZilFoi - !^c!!/E|/oi, wR2 = [Zw(/o2 - Fc2)2/Zw(Fo2)2]1/2.
drazone ligands [16, 17]. Distortion of the octahedral coordinatio
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