Tri-, tetra- and octa-metallic vanadium(III) clusters from new, simple starting materials: interplay of exchange and anisotropy effects

The crystal structure of the monomeric vanadium(III) species mer-[V(bipy) Cl-3(MeCN)] (1; bipy = 2,2'-bipyridine) is reported. The solvothermal reaction of [V(bipy)Cl-3(MeCN)] with Na(O2CPh) yields the T-shaped cluster [V-3(O)Cl-3(O2CPh)(2)(bipy)(2)(OEt)(2)], magnetic studies of which show strong intramolecular antiferromagnetic coupling giving a well isolated S = 1 ground state. Solvothermal treatment of 1 with triols yields a series of polymetallic clusters [V4Cl6(thme)(2)(bipy)(3)], [V3Cl4(Hcht)(2)(bipy)(2)]Cl and [V-8(OH)(2)Cl-4(cht)(4)(O2CPh)(6)(bipy)(2)], structurally related to previously reported {M-4} centred triangles. Magnetic studies of this series reveal very weak intramolecular antiferromagnetic exchange and very strong local zero-field splitting effects.