Chemical Physics Letters vol:320 issue:5-6 pages:575-581
DFT (B3LYP) calculations have been performed to study the CoC2 molecule in its different geometric conformations and electronic states. The energies have been refined using ab initio multiconfigurational CASSCF/CASPT2 calculations. Both approaches are in a good semi-quantitative agreement between themselves and predict the symmetric triangular (C-2 nu) structure to be more stable than the linear (C-infinity nu) conformation. The ground state has been found to be a quartet, which can formally be regarded as an ionic Co2+-C-2(2-) complex, resulting from a transfer of the two 4s electrons of the cobalt atom to the 3 sigma(g) orbital of the C-2 ligand and distributing the remaining seven valence electrons over the split 3d orbitals. (C) 2000 Elsevier Science B.V. All rights reserved.