Ab initio MO calculations were carried out on transition-metal ions (Sc~+ , V~+ , Mn~+ , Co~+ , and Cu~+ ) with carbene (CH-2) at RHF/6- 311G level. In order to gain additional insight into the nature of bonding in these complexes, energy decomposition analyses were performed in detail using a one-electron shift operator. With this method the coupling term in the energy decomposition analyses could be eliminated completely. According to our calculations, the bond of Sc~ + -CH-2 formed by the a and TC donating interactions and the TT back- donating interaction, but the bond of Cu ~+ -CH is composed of the a donating interaction and the a and TT back-donating interactions. The bonds in other complexes were also discussed in brief.

Key words: CARBENE, AB INITIO CALCULATION, SCANDIUM COMPLEX, VANADIUM COMPLEX, MANGANESE COMPLEX, COBALT COMPLEX, COPPER COMPLEX, ELECTRONIC STATES