Structures and Magnetic Properties of Dinuclear Vanadium(III) Complexes with Alkoxo Bridge

Several dinuclear vanadium(III) complexes were prepared using a heptadentate dinucleating ligand containing a bridging alkoxo group. The structures of [V2(dpot)(m-hbza)(H2O)2]·H2O (1b), [V2(bza)(OH)(tphpn)(H2O)2]Cl3·8H2O (2), and [V2(hpnbpda)2]·12H2O (3a) were determined by X-ray crystallography (dpot: 2-oxo-1,3-diaminopropane-N,N,N′,N′-tetraacetate, m-hbza: m-hydroxybenzoate, bza: benzoate, tphpn: N,N,N′,N′-tetrakis(2-pyridylmethyl)-2-oxo-1,3-propanediamine, hpnbpda: N,N′-bis(2-pyridylmethyl)-2-oxo-1,3-propanediamine-N,N′-diacetate). Each vanadium(III) center of 1b adopts a distorted octahedral structure, and the two vanadium centers are bridged by an alkoxo group of dpot and a carboxylato group of m-hbza bridge. Each vanadium center of 2 and 3a, however, takes a heptacoordinate structure. The coordination polyhedron of 2 can be regarded as a capped octahedron, while that of 3a as a pentagonal bipyramid. The two vanadium(III) centers are ferromagnetically coupled in 1b (J = 23.7 cm−1) and 2 (J = 14.6 cm−1), whereas in 3a they are antiferromagnetically coupled (J = −35.2 cm−1). The electrochemistry of the dpot and hpnbpda complexes has also been investigated.