The dependence of metal–ligand bond lengths on the nature of ligand groups: centroids of overlap density in metal–ligand bonds

Abstract

Bond lengths in several complexes of third-row transition-metal halides with tertiary phosphines (ML₂Cl₄ where M = W^IV, Re^IV, Os^IV, Ir^IV, and Pt^IV) are discussed in relation to a maximum overlap criterion. Theoretical metal bond radii, defined as the distances from the metal to the centroid of overlap density of the metal–ligand bonds, agree well with the variations in bond lengths. Some comments are made on the Cl n.q.r. spectra of the complexes. The problem of ‘d’ orbital involvement in phosphorus pentafluoride and phosphorus pentachloride is discussed with special reference to the differing strengths of axial and equatorial bonds.