Structural chemistry of complexes of (n − 1)d10nsm metal ions with β-N-donor substituted thiolate ligands (m = 0, 2)

The molecular structures of several d10 metal ion complexes with 2-amino or 2-imino substituted thiolate ligands, derived from 2-aminoethanethiol, 2-(mercaptomethyl)pyridine, 2-aminobenzenethiole, and 8-mercaptoquinoline, are presented. Since ligand field stabilization energy is absent, the complexes display a large variety of co-ordination numbers and geometries around the metal centers. Distortions from ideal tetrahedral or trigonal bipyramidal configurations are discussed in terms of special structural parameters. In contrast to thiolate ligands that lack additional donor atoms and thus form oligo- or poly-nuclear complexes, the β-N donor group stabilizes mono-nuclear complexes in many cases. In that respect, the number of donor atoms available per metal centre is decisive. Due to its importance for biological systems as compared to the other elements dealt with in this review, there are many more structurally characterized complexes with N,S-donor ligands for Zn2+ than for any other d10 ion. Significant structural differences concerning co-ordination number and structural parameters occur between Zn2+ on one hand and Cd2+/Hg2+ complexes on the other. With tetraco-ordinate d10 s2 ions pseudo trigonal bipyramidal structures occur as well as pseudo square pyramidal structures.