Studies of the oxovanadium(IV)—oxalate system: syntheses and crystal structures of binuclear (Ph 4P) 2[(VO) 2(H 2O) 2(C 2O 4) 3]·4H 2O and of the one-dimensional chain material, (Ph 4P)[VOCl(C 2O 4)

Abstract

The hydrothermal reactions of (Ph 4P)[VO 2Cl 2] and H 2C 2O 4 at 150 and 125°C yield (Ph 4P) 2[V 2O 2(H 2O) 2(C 2O 4) 3]·4H 2O ( 1) and (Ph 4P)[VOCl(C 2O 4)] ( 2), respectively. The structure of the molecular anion of 1 consists of a binuclear unit of oxovanadium(IV) octahedra bridged by a bisbidentate oxalate group. The VO 6 coordination geometry at each vanadium site is defined by a terminal oxo group, an aquo ligand, and four oxygen donors — two from the bisbidentate bridging oxalate and two from the terminal bidentate oxalate. The structure of 2 consists of discrete Ph 4P + cations occupying regions between [VOCl(C 2O 4)] − ∞ spiral chains. The structure of the one-dimensional anionic chain exhibits V(IV) octahedra bridged by bisbidentate oxalate groups. Crystal data: 1·4H 2O, monoclinic P2 1/n, a = 12.694(3), b = 12.531(3), c = 17.17(3) A ̊ , β = 106.32(2)°, V = 2621.3(13) A ̊ 3, Z = 2, D calc = 1.501 g cm −3 , structure solution and refinement converged at a conventional residual of 0.0518; 2, tetragonal P4 3, a = 12.145(2), c = 15.991(3) A ̊ , V = 2358.7(12) A ̊ 3, Z = 4, R = 0.0452 .