The biggest contributors to this family are polymetallic clusters of V, principally investigated for their catalytic properties. The first reported example was the dimer [RNH3][V V 2O2(H1TBC [8])] (1), published in 1990. Complex 1 (Fig. ) was synthesised from the reaction of [VO(O i Pr)3] with H8TBC [8] in THF. The core of the complex describes a [V2O2] dimer with the two metal ions bridged by two µ-O(Ph) atoms from the heptadeprotonated H1TBC [8] ligand. The latter is in the 'saddle-shaped' conformation, twisting in such a way as to provide five O-atoms to each octahedral V V centre, the sixth coordination site on each metal ion being occupied by a terminally bonded oxide (O 2-) ion.