Structure and bonding in late transition metal dinuclear complexes with local trigonal planar geometries

Abstract

A study of the structures preferred by the M₂X₂ rings in the dinuclear complexes of late transition metals of types [M₂(μ-XR₂)₂L₂] and [M₂(μ-XR₃)₂L₂] is presented, based on qualitative orbital arguments supported by DFT calculations on model compounds. The main conclusions agree well with the results of a structural database analysis. With the simplified electron counting scheme applied, complexes with six or four electrons available for bonding of the M₂X₂ framework are predicted to have two possible minimum energy structures, with either a short M–M or X–X distance, whereas compounds with eight framework electrons are expected to present no short through-ring distance. Such behavior is consistent with the framework electron counting rules reported earlier for compounds with different coordination spheres and provides a general description of the structure and bonding in a variety of compounds with M₂X₂ diamonds.