Increased CO adsorption on supported VIB and IB metals

Unusual support effect on metal–CO interaction is shown occurring when an electron occupies an antibonding level in the metal–CO system. Then, the presence of a reducible support increases the interaction since the unpaired electron is formally transferred towards the support. Such effect is manifest for metal elements from columns VIB and IB. A reducible support allows a formal electronic transfer, oxidizing the metal adsorbed. Accordingly, the metal–CO interaction should be considered as the interaction between CO and a metal cation (M+) which is much stronger than the interaction with the neutral atom. Spin localization confirms our analysis. This effect has consequences on the geometry of adsorption, decreasing the M–C distances.