Theoretical studies on the electronic and thermodynamic properties of several electronic states are presented for the VC2 molecule, the VC2- anion, and the VC2+ cation employing state-of-the-art techniques that included up to 12 million configurations. The ground and the low-lying electronic states of these three species have been found to have C-2v triangular structures. On the basis of our computed results, we have suggested an assignment of the observed anion photodetachment spectra of VC2- and predicted transitions that were not observed. Our computed electron affinity is in excellent agreement with experiment. The observed thermodynamic properties of reactions involving VC2, VC2-, and VC2+ are corrected using the computed gas phase properties of the molecule and the partition functions. The bent quartet states of VC2 exhibit large dipole moments (8.65-9.3 D). (C) 2003 American Institute of Physics.