Bonding in square-planar MCl(CX)[P(i-Pr) 3] 2 complexes of rhodium and iridium (X = O and CH 2) studied by UV photoelectron spectroscopy and DV-Xα calculations

Abstract

The electronic structure of square-planar rhodium(I) and iridium(I) complexes of general composition trans-MCl(CX)[P(i-Pr) 3] 2 (X = O and CH 2) has been investigated by means of gas-phase UV photoelectron spectroscopy (UPS). The results, which are supported by discrete variational DV-Xα calculations, confirm that carbon monoxide and vinylidene act as ligands with very similar properties. The spacing of d orbitals in the iridium complexes seems to be different from that in the rhodium analogues, probably owing to a more significant interaction between the d xz level of iridium and the empty d orbitals of the phosphine ligands.