Molecular structures, relative energies, vibrational spectra and bond dissociation energies of the seven-coordinate, 18-valence-electron vanadium carbonyl complex, V(CO)(7)(+), are predicted theoretically. A C-3v symmetry capped octahedral structure is found to be the global minimum and predicted CO vibrational frequencies range from 2023 to 2122 cm(-1), generally consistent with experiment for known cationic carbonyl complexes. The lowest energy structure of V(CO)(6)(+) is also determined, a triplet D-3d structure. The resulting bond dissociation energy, D-e, for CO ligand loss is predicted to be 11 kcal mol(-1) with B3LYP, in good agreement with experiment, while BP86 and MP2 predict much higher values of 30 and 39 kcal mol(-1). (C) 2008 Published by Elsevier B.V.