Gas-phase infrared photodissociation spectroscopy of tetravanadiumoxo and oxo-methoxo cluster anions

摘要

The infrared spectra of the binary vanadium oxide cluster anions V4O9- and V4O10- and of the related methoxo clusters V4O9(OCH3)(-) and V4O8(OCH3)(2)(-) are recorded in the gas phase by photodissociation of the mass-selected ions using an infrared loser. For the oxide clusters V4O9- and V4O10-, the bonds of the terminal vanadyl oxygen atoms, nu(V-O-t), and of the bridging oxygen atoms, nu(V-O-b-V), are identified clearly. The clusters in which one or two of the oxo groups are replaced by methoxo ligands show additional absorptions which are assigned to the C-O stretch, nu(C-O). Density functional calculations are used as a complement for the experimental studies and the interpretation of the infrared spectra. The results depend in on unusual way on the functional employed (BLYP versus B3LYP), which is due to the presence of both V-O(CH3) single and V=O double bonds as terminal bonds and to the strong multireference character of the latter.