Solvothermal syntheses of high-nuclearity vanadium(III) clusters

Superheating alcohol solutions of simple trimetallic vanadium(III) precursors gives the octa- and decametallic vanadium(III) clusters [V-8(OEt)(8)(OH)(4)(O2CPh)(12)] (1) and [V-10(OMe)(20-)(O2CMe)(10)] (2) Cluster 2 is the largest vanadium(III) cluster synthesised to date. Thus solvothermal synthetic techniques are an excellent route to high-nuclearity vanadium(III) clusters. Both 1 and 2 consist of a planar or near-planar array of V-III ions. The metal ions in 1 are bridged by either a p2-hydroxide and two mu(2)-benzoate groups or two mu(2)-ethoxides and a mu(2)-benzoate groups, the two bridging arrangements alternating around the ring. In 2 each pair of neighbouring metal ions is bridged by two mu(2)-methoxides and a mu(2)-acetate, and this molecule is the V-III. analogue of Lippard's famous ferric wheel. Preliminary magnetic susceptibility studies show the exchange coupling in both complexes to be anti-ferromagnetic in nature, with the coupling stronger in 1 than in 2.