Zhao‐Hui Zhou, H. Wan, Shengzhi Hu
Sep 1, 1995
Citations
0
Influential Citations
44
Citations
Journal
Inorganica Chimica Acta
Abstract
Abstract The two dimers potassium-ammonium dioxocitratovanadate (V), K2(NH4)4[VO2(cit)]2·6H2O (1) and sodium oxocitratovanadate (IV), Na4[VO(cit)]2·6H2O (2) have been prepared by the reactions of citric acid and metavanadate in neutral solution. Complex 1 crystallizes in the triclinic space group P 1 with unit cell parameters: α = 8.894(1), b = 9.783(1), c = 9.930(2) A , σ = 70.00(1), β = 88.09(1), γ = 68.42(1)°, V = 750.8 A 3 , Z = 1, R = 0.035 for 2622 observed reflections. The dimeric anion contains a centrosymmetric planar four-member V2O2 ring with the bridging hydroxyl oxygens. The citrate ion is coordinated via oxygen atoms of the hydroxyl and α-carboxylato groups, and the two acetato branches are not coordinated to vanadium. The principal V-O dimensions are: V-O(hydroxy), 1.961(2), 2.005(2) A; V-O(σ-carboxy), 1.981(3) A. Complex 2 crystallizes in the monoclinic space group P21/n with unit cell parameters: a = 10.120(2), b = 10.822(4), c = 11.934(4) A , β = 111.57(2)°, V = 1215.4 A 3 , Z = 2, R = 0.035 for 2255 observed reflections. The dimer contains a similar planar V2O2 ring with bridging hydroxyl oxygens. The tetradentate citrato ligands coordinate via hydroxyl and α-carboxylato oxygens to one vanadium, and via two acetato branches to the two vanadiums in the dimer. The principal V-O dimensions are: V-O(hydroxy), 1.971(2), 2.206(2) A; V-O (α-carboxy), 2.038(2) A: V-O(β-carboxy), 2.017(2), 2.032(2) A. The coordination number of the vanadium ions in complex 1 and complex 2 is therefore five and six, respectively.