A Class of Trinuclear Clusters with Carbonyl Bridging

Abstract

Abstract The impetus for this work was the structure of a trinuclear complex with two carbonyl groups showing incipient triple bridging ‐ Cp 2 Rh 3 (CO) 4 − . Its structure, barrier to rotation of one Rh(CO) 2 − piece vs. the rest of the molecule, and the nature of the bridging carbonyl interaction are analyzed. Isolobal analogies form an interesting connection between this complex and a bridged isomer of the recently synthesized carbene complexes, Cp 2 Rh 2 (CO) 2 CR 2 , one isomer of Cp 2 Rh 3 (CO) 3 , and hypothetical carbyne complexes Cp 2 Rh 2 (CO) 2 CH +,− . A general bonding model for Cp 2 Rh 2 (μ‐CO) 2 X complexes is constructed. The model, rich in geometrical detail, allows minima for the bridging carbonyl groups bending toward and away from the bonded ligand X.