STRUCTURES AND MAGNETIC-PROPERTIES OF DINUCLEAR VANADIUM(III) COMPLEXES WITH ALKOXO BRIDGE

Several dinuclear vanadium(III) complexes were prepared using a heptad entate dinucleating ligand containing a bridging alkoxo group. The str uctures of [V-2(dpot)(m-hbza)(H2O)(2)]. H2O (1b), [V-2(bza)(OH)(tphpn) (H2O)(2)]Cl-3 . 8H(2)O (2), and [V-2(hpnbpda)(2)]. 12H(2)O (3a) were d etermined by X-ray crystallography t-2-oxo-1,3-diaminopropane-N,N,N',N '-tetraacetate, m-hbza: m-hydroxybenzoate, bza: benzoate, tphpn: etrak is(2-pyridylmethyl)-2-oxo-1,3-propanediamine, hpnbpda: lmethyl)-2-oxo- 1,3-propanediamine-N,N'-diacetate). Each vanadium(III) center of Ib ad opts a distorted octahedral structure, and the two vanadium centers ar e 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 heptacoord inate structure. The coordination polyhedron of 2 can be regarded as a capped octahedron, while that of 3a as a pentagonal bipyramid. The tw o vanadium(III) centers are ferromagnetically coupled in Ib (J=23.7 cm (-1)) and 2 (J=14.6 cm(-1)), whereas in 3a they are antiferromagnetica lly coupled (J=-35.2 cm(-1)). The electrochemistry of the dpot and hpn bpda complexes has also been investigated.