The fact that the stable mononuclear vanadium carbonyl V(CO)(6) fails to satisfy the 18-electron rule has led to an investigation of the binuclear vanadium carbonyls V-2(CO)(n) (n = 10-12) using methods from density functional theory. There are several important experimental studies of these homoleptic binuclear vanadium carbonyls. The global minimum for V-2(CO)(12) is a singlet structure having two V(CO)(6) units linked by a long V-V single bond (3.48 angstrom by B3LYP or 3.33 angstrom by BP86) without any bridging CO groups. For V-2(CO)(11) the global minimum is a singlet structure V-2(CO)(10)(eta(2)-mu-CO) with a four-electron pi-donor bridging CO group. For V-2(CO)(10) the global minimum is an unsymmetrical singlet (OC)(4)VV(CO)(6) structure with three semibridging CO groups and a V-V distance of 2.54 angstrom (B3LYP) or 2.51 A (BP86), suggesting a VV triple bond. The theoretical nu(CO) frequencies of this V-2(CO)(10) isomer agree approximately with those assigned by Ishikawa et al. (J. Am. Chem. Soc. 1987, 109, 6644) to a V-2(CO)(10) isomer produced in the photolysis of gas-phase V(CO)(6). In contrast, the laboratory bridging nu(CO) frequency assigned to V-2(CO)(12) by Ford et al. (Inorg. Chem. 1976, 15, 1666) seems more likely to arise from the lowest-lying triplet isomer of V-2(CO)(11).