Structures, relative energies, vibrational spectra, and ESR parameters of the 17e(-) molecule V(CO)(6) in O-h, D-3d, D-4h, and D-2h symmetry have been computed with density functional and high-level ab initio methods. At all theoretical levels applied, the same energetic order is obtained, D-3d < D-2h < D-4h < O-h, with the D-2h structure as a transition state connecting equivalent D-3d species. At the RCCSD(T)/AE2 level using UBP86/AE2 geometries, the energies of the D-2h, D-4h and O-h species relative to that of D-3d minimum are predicted to be 210, 535, and 731 cm(-1), respectively. According to molecular dynamics simulations on the UBP86/AE1 potential energy surface, the D3d minimum is preserved at very low temperatures (around 16 K), whereas at 300 K the molecule is highly fluxional with an averaged structure indistinguishable from that of [V(CO)6](-) with its O-h symmetric ground state. Nearly complete IR and Raman spectra Of V(CO)(6) and V((CO)-C-13)(6) have been recorded at 300 K for the first time in the gas phase, in solution, and at cryogenic temperatures in Ne and Ar matrices. The spectra show a pronounced temperature dependence, especially for the Jahn-Teller active modes, E-g and T-2g. The observed infrared matrix spectra generally agree well with the calculated spectrum (BP86/AE2 level) for the D-3d structure and much less with that of the D-4h isomer. The A(1g) modes in the Raman spectra are reasonably well reproduced computationally in the harmonic approximation, whereas this approximation breaks down for the E-g and T-2g bands, as expected. Further evidence for the D-3d symmetry Of V(CO)(6) is obtained from a reanalysis of the experimental ESR spectrum that is reported in the literature. The observed ordering of the hyperfine coupling constants A(\\) and A(perpendicular to) is reproduced theoretically only when distortion to D-3d symmetry is assumed. In addition, the bonding properties Of V(CO)(6) are compared to those Of [V(CO)6](-) and Cr(CO)(6).