Structure and Magnetism of Dibridged Vanadium(IV) Hydrotris(pyrazolyl)borate Dimers

Abstract

The synthesis and characterization of four dinuclear V(IV) complexes are described: 1, [LVO(μ-(Ph)2PO2)LVO]; 2, [LVO(μ-(Ph)HPO2)2LVO]; 3, [LVO(μ-OH)2LVO]; and 4, [LVO(μ-OH)(μ-OAc)LVO] (where L = hydrotris(pyrazolyl)borate). X-ray crystal structural analysis of 1−4 gave the following parameters: 1, C46H46B2N14O6P2V2, P1̄, a = 12.249(2) Å, b = 13.951(3) Å, c = 16.391(3) Å, α = 93.95(3)°, β = 100.53(3)°, γ = 110.01(3)°, Z = 2; 2, C47H48B2N19O9P3V3, P1̄, a = 9.927(2) Å, b = 12.307(2) Å, c = 24.878(3) Å, α = 98.12(1)°, β = 100.79(1)°, γ = 91.05(1)°, Z = 2; 3, C22H28B2N14O4V2, Pbca, a = 10.698(1) Å, b = 15.414(3) Å, c = 17.865(3) Å, Z = 4; 4, C24H24B2N12O5V2, C2/c, a = 34.252(4) Å, b = 14.623(2) Å, c = 15.387(2) Å, β = 102.32(1)°, Z = 8. Magnetic measurements indicate that all the compounds except 4 are moderately antiferromagnetically coupled. A rationalization for the magnetic behavior of these and other complexes of this type based on a direct overlap model modulated by the conformation of the eight-membered V(μ-OXO)2V ring is proposed.