TWO ISOMERIC STRUCTURES OF OXOVANADIUM(V) COMPLEXES WITH HYDRAZONE AND 8-HYDROXYQUINOLINE LIGANDS
Two new oxovanadium(V) complexes [VOL1(HQ)] (1) and [VOL2(HQ)] (2) are prepared by the reaction of [VO(acac)2] (where acac = acetylacetonate), 8-hydroxyquinoline (HHQ) with 4-bromo-Nc-(3-ethoxy-2-hydroxybenzylidene)benzo2hydrazide (H2L1) and 2-bromo-Nc-(3ethoxy-2-hydroxybenzylidene)benzohydrazide (H2L ), respectively, in methanol. Crystal and molecular structures of the complexes are determined by elemental analysis, infrared spectroscopy, and single crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic space group P21/c, with unit cell dimensions a = 12.5236(13) Å, b = 22.5260(15) Å, c = 16.7029(13) Å, E = 90.054(2)q, V = 4712.0(7) Å3, Z = 8, GOOF = 1.024, R1 = 0.0586 and wR2 = 0.0835. Complex 2 crystallizes in the triclinic space group P-1, with unit cell dimensions a = 7.4344(12) Å, b = 10.8677(16) Å, c = 14.687(2) Å, D = 85.327(5)q, E = 77.357(5)q, J = 84.896(5)q,V = 1150.9(3) Å3, Z = 2, GOOF = 1.153, R1 = 0.0917 and wR2 = 0.3014. The V atoms are in the octahedral coordination. Thermal stability of the complexes is also studied.
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The V atoms are in the octahedral coordination. <...> Thermal stability of the complexes is also studied. <...> Recently, our research group has reported a few vanadium complexes with biological activities [ 12, 13 ]. 8-Hydroxyquinoline (HQ) is a widely known bidentate ligand in coordination chemistry [14—16 ], however, only two HQ coordinated oxovanadium complexes with hydrazone ligands have been reported so far [ 17, 18 ]. <...> In the present paper, two new oxovanadium(V) complexes with hydrazone and HQ ligands, [VOL1(HQ)] (1) and [VOL2(HQ)] (2) (H2L1 = 4-bromo-N-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide, H2L2 = 2-bromo-N-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide; Scheme 1), have been presented. Sheng G.-H., Cheng X.-S., You Z.-L., Zhu H.-L., 2015 ethoxy-2-hydroxybenzylidene)benzohydrazide (H2L2), respectively, in methanol. <...> Crystal and molecular structures of the complexes are determined by elemental analysis, infrared spectroscopy, and single crystal X-ray diffraction. <...> C, H, and N elemental analyses were performed with a Perkin-Elmer elemental analyzer. <...> Thermal stability analysis was performed on a Perkin-Elmer Pyris Diamond TGA-DTA thermal analysis system. <...> Brown block-shaped crystals suitable for X-ray single crystal diffraction formed at the bottom of the vessel. <...> All of the nonhydrogen atoms were refined anisotropically. <...> The molecular structures and atom numbering schemes of complexes 1 and 2 are shown in Figs. 1a, b and 2, respectively. <...> ORTEP plot of the molecular structure of 2. <...> The V atoms in the complexes are in the octahedral coordination, with three donor atoms of the hydrazone ligands and the hydroxy O atom of the HQ ligand defining the equatorial plane, and with one oxo O atom and the pyridine N atom of the HQ ligand occupying the axial positions. <...> In both complexes the bond lengths are comparable to each other, and also similar to those observed in the mononuclear oxovanadium(V) complexes with the octahedral coordination [ 17, 18 ]. <...> Differential thermal (DTA) and thermal gravimetric analyses (TGA) were conducted to examine the stability of the complexes under the air atmosphere and with the standard corundum crucible sample holder (Fig. 3, a for 1 and Fig. 3, b for 2). <...> DTA-TGA curve of 1 (a) and DTA-TGA curve of 2 (b) CONCLUSIONS In summary, two new <...>
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