Inorganic stereochemistry: Geometric isomerism in bis-tridentate ligand complexes

摘要

In this review, we analyze the stereochemistry of hexacoordinated metal complexes with flexible tridentate ligands. Unlike rigid ligands, which can adopt only specific coordination modes, flexible ligands open more possibilities to fine-tuning the system for a specific application. Bis-tridentate [M(A-B-A)(2)] complexes of flexible ligands can form three geometric isomers: mer, trans-fac, and cis-fac. The analysis of crystallographic data for 844 structures found in the Cambridge Structural Database (CSD) elucidates influences on the formation of different isomers, such as steric and electronic properties of the ligand and metal ion, type and substitution of donor atoms, and the possibility of non-covalent interactions. (C) 2021 Elsevier B.V. All rights reserved.