Associative versus dissociative binding of CO to 4d transition metal trimers: A density functional study

✍ Scribed by Matthew A. Addicoat; Mark A. Buntine; Brian Yates; Gregory F. Metha

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 218 KB
• Volume: 29
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.20912

✦ Synopsis

Abstract

Density functional calculations were performed to determine equilibrium geometrical structures, transition states and relative energies for M~3~ clusters (M = Nb, Mo, Tc, Ru, Rh, Pd, Ag) reacting with CO, leading to proposed reaction pathways. For the Nb~3~, Mo~3~, and Tc~3~ clusters, the lowest energy structure correlates to dissociated CO, with the C and O atoms bound on opposite sides of the metal triangle. For all other trimers, the lowest energy structures maintain the CO moiety. In the case of Pd~3~ and Ag~3~ the dissociated geometries lie higher in energy than the sum of the separated reactants. In most cases, several multiplicities were found to be similar in energy and for Mo~3~CO and Pd~3~CO singlet‐triplet minimum energy crossing points were identified. In the case of Rh~3~CO, minimum energy crossing points for the doublet, quartet, and sextet reaction pathways were determined and compared. The electron densities of pertinent M~3~CO species were investigated using Natural Bond Order calculations. It was found that the effect of the metal trimer on the energy of the pure p‐type π* antibonding orbital of carbon monoxide directly correlates with the occurrence of CO dissociation. © 2008 Wiley Periodicals, Inc.J Comput Chem, 2008.