Expanding the Concepts Trans Influence and Back-Donation: Hybrid and Side Donations in [Cp*M^III(L)XY] (M = Rh, Ir) Complexes with CO, CN^–, and CNR Ligands. A Window to Cis Influence

Analysis of the bonding contributions in molecules [MIIICp*(L)XY] (M = Rh, Ir; Cp* C5Me5; L CO, CN–, CNR) has uncovered a rich variety types interaction that seem to have escaped detection so far, spite continuous popularity cyclopentadienyl transition-metal complexes since 1970s. At variance with M—C≡O bond square-planar systems, which shows typical metal-to-CO π-back-donation, nonorthogonal arrangement plane and Rh—C≡O fragment pseudooctahedral geometry lead observation many direct lateral donations from other ligands do not involve metal orbitals, we name side donations, for instance, → π*(CO), Cl F π*(CO). Hybrid partially involving metal, M–Caryl are also observed. The summation multiple than back-donation can easily account about 20% electron donation π*(C≡O) orbitals.