Geometric and electronic structures of V2C2− and V2C2 studied by photoelectron spectroscopy and density-functional calculations

The electronic and geometric structures of V2C2− were investigated by photoelectron spectroscopy (PES) and density-functional theory (DFT). The experimental PES spectrum was compared with the simulated ones for several low-energy isomers obtained by the structural optimization procedure. The spectrum is found to be best reproduced by the most stable isomer, which has a doublet spin multiplicity and a planar distorted four-membered-ring geometry with a transannular V–C bonding. The VC2 subunit in V2C2− is almost identical with the optimized structure of free VC2. The DFT study of V2C2 shows that it has the singlet ground state with a geometry similar to that of the anion.