Delocalized bonding in tetrahedral organo-transition metal clusters: an EHMO study of metal vertex rotations in Co2Fe(CO)9S, CpMoCo2(CO)8CR, and in Cp2Mo2(CO)4(RCCR)

Molecular orbital calculations at the extended Hückel level are used to rationalize the barriers to vertex rotation in the tetrahedral metal cluster complexes FeCo 2 (CO) 9 S, 2, and (C 5 H 5 )MoCo 2 (CO) 8 CH, 3. It is shown that, in accord with experimental observations on 2, rotation of an Fe(CO) 3 fragment through 60° brings about a weakening of the metal–metal bonding interactions within the FeCo 2 triangle. In the MoCo 2 cluster, 3, …