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Monomeric Oxovanadium(IV) Compounds of the General Formula cis-[VIV(O)(X)(LNN)2]+/0 {X = OH-, Cl-, SO42- and LNN = 2,2‘-Bipyridine (Bipy) or 4,4‘-Disubstituted Bipy}

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journal contribution
posted on 12.01.2004, 00:00 by Georgios D. Triantafillou, Evagelos I. Tolis, Aris Terzis, Yiannis Deligiannakis, Catherine P. Raptopoulou, Michael P. Sigalas, Themistoklis A. Kabanos
Reaction of [VIVOCl2(THF)2] in aqueous solution with 2 equiv of AgBF4 or AgSbF6 and then with 2 equiv of 2,2‘-bipyridine (bipy), 4,4‘-di-tert-butyl-2,2‘-bipyridine (4,4‘-dtbipy), or 4,4‘-di-methyl-2,2‘-bipyridine (4,4‘-dmbipy) affords compounds of the general formula cis-[VIVO(OH)(LNN)2]Y {where LNN = bipy, Y = BF4- (1), LNN = 4,4‘-dtbipy, Y = BF4- (2·1.2H2O), LNN = 4,4‘-dmbipy, Y = BF4- (3·2H2O), and LNN = 4,4‘-dtbipy, Y = SbF6- (4)}. Sequential addition of 1 equiv of Ba(ClO4)2 and then of 2 equiv of bipy to an aqueous solution containing 1 equiv of VIVOSO4·5H2O yields cis-[VIVO(OH)(bipy)2]ClO4 (5). The monomeric compounds 15 contain the cis-[VIVO(OH)]+ structural unit. Reaction of 1 equiv of VIVOSO4·5H2O in water and of 1 equiv of [VIVOCl2(THF)2] in ethanol with 2 equiv of bipy gives the compounds cis-[VIVO(OSO3)(bipy)2]·CH3OH·1.5H2O (6·CH3OH·1.5H2O) and cis-[VIVOCl(bipy)2]Cl (7), respectively, while reaction of 1 equiv of [VIVOCl2(THF)2] in CH2Cl2 with 2 equiv of 4,4‘-dtbipy gives the compound cis-[VIVOCl(4,4‘-dtbipy)2]Cl·0.5CH2Cl2 (8·0.5CH2Cl2). Compounds cis-[VIVO(BF4)(4,4‘-dtbipy)2]BF4 (9), cis-[VIVO(BF4)(4,4‘-dmbipy)2]BF4 (10), and cis-[VIVO(SbF6)(4,4‘-dtbipy)2]SbF6 (11) were synthesized by sequential addition of 2 equiv of 4,4‘-dtbipy or 4,4‘-dmbipy and 2 equiv of AgBF4 or AgSbF6 to a dichloromethane solution containing 1 equiv of [VIVOCl2(THF)2]. The crystal structures of 2·1.2H2O, 6·CH3OH·1.5H2O, and 8·0.5CH2Cl2 were demonstrated by X-ray diffraction analysis. Crystal data are as follows:  Compound 2·1.2H2O crystallizes in the orthorhombic space group Pbca with (at 298 K) a = 21.62(1) Å, b = 13.33(1) Å, c = 27.25(2) Å, V = 7851(2) Å3, Z = 8. Compound 6·CH3OH·1.5H2O crystallizes in the monoclinic space group P21/a with (at 298 K) a = 12.581(4) Å, b = 14.204(5) Å, c = 14.613(6) Å, β = 114.88(1)°, V = 2369(1), Z = 4. Compound 8·0.5CH2Cl2 crystallizes in the orthorhombic space group Pca21 with (at 298 K) a = 23.072(2) Å, b = 24.176(2) Å, c = 13.676(1) Å, V = 7628(2) Å3, Z = 8 with two crystallographically independent molecules per asymmetric unit. In addition to the synthesis and crystallographic studies, we report the optical, infrared, magnetic, conductivity, and CW EPR properties of these oxovanadium(IV) compounds as well as theoretical studies on [VIVO(bipy)2]2+ and [VIVOX(bipy)2]+/0 species (X = OH-, SO42-, Cl-).