Analysis of the supramolecular structures of Sb(III) and Sb(V) catecholate complexes from the viewpoint of ligand solid angles

Abstract

The ligand solid angle approach has been successfully applied to the analysis of the catecholate complexes of Sb(III) and Sb(V). The Sb(III) complexes possess an electron lone pair that influences their molecular structure but does not behave as a classic “ligand” when intermolecular interactions are concerned. The Sb(III) complexes in solid state form numerous intermolecular interactions that effectively increase metal shielding, and herein we analyze the effects of the lone pair of electrons on the complex coordination geometry. In the five-coordinate R3CatSb(V) complexes (Cat = catecholate ligand, R = Ph, Me, Cl) the metal is shielded by 87(3)% and multiple intermolecular contacts are observed. The central metal in the six-coordinate antimony(V) complexes R3CatSb(V) · L is shielded to the extent of 89(2)% and no strong attractive intermolecular interactions are detected in solid state. Thus, the metal shielding in excess of 85% is required to prevent complex dimerization or additional ligation of the central atom by a nucleophile.