Infrared Photodissociation Spectroscopy of Vanadium Oxide-Carbonyl Cations

Mass selected vanadium oxide carbonyl cations of the form VOm(CO)(n)(+) (m = 0-3 and n = 3-6) are studied via infrared laser photodissociation spectroscopy in the 600-2300 cm(-1) region. Insight into the structure and bonding of these complexes is obtained from the number of infrared active bands, their relative intensities and their frequency positions. Density functional theory calculations are carried out in support of the experimental data. The effect of oxidation on the carbonyl stretching frequencies of VO(CO)(n)(+), VO2(CO)(n)(+), and VO3(CO)(n)(+) complexes is investigated. All of these oxide-carbonyl species have C-O stretch vibrations blue-shifted from those of the pure vanadium ion carbonyls. The V-O stretches of these complexes are also investigated, revealing the effects of CO coordination on these vibrations. The oxide-carbonyls all have a hexacoordinate core analogous to that of V(CO)(6)(+). The fully coordinated vanadium monoxide carbonyl species is VO(CO)(5)(+), and those of the dioxide and trioxide are VO2(CO)(4)(+) and VO3(CO)(3)(+), respectively.