Germanium coordination compounds: Classification and analysis of crystallographic and structural data

Abstract

This review covers the crystallographic and structural data for almost two hundred coordination compounds of germanium. In the majority the oxidation number of germanium is +4, with about one quarter being +2. Up to ten Ge atoms are found in anionic clusters. Coordination numbers from four to six with geometries of tetrahedral, trigonal bipyramidal, square pyramidal, octahedral and pseudo-octahedral for the Ge(IV) derivatives, and two to four with geometries governed by a lone pair of electrons. The most common donor atoms are N and O. Distortion or configurational isomerism is reported in about 10% of the derivatives. Relationships between ligands, bond distances and bond angles are discussed in terms of steric and electronic influences.