Comment on 'the origin of anomalous bond dissociation energies of V+(H2)n clusters'

In a recent study, we reported experimental determinations of bond dissociation energies and entropies for V + (H 2 ) n ( n = 1 to 6) and suggested that a spin change from quintet to triplet occurs upon addition of the sixth H 2 ligand. A very recent theoretical paper by Niu et al. disputes this and concludes that the experimental results are consistent with purely quintet clusters (J. Niu, B.K. Rao, S.N. Khanna and P. Jena, Chem. Phys. Letters 230 (1994) 299). In this Comment, we restate our reasons for the proposed spin charge and argue that important aspects of the results of Niu et al. are incorrect.