Bis- and tris-phosphinostannane gold complexes featuring Au → Sn dative interactions: Synthesis, structures, and DFT calculations

Abstract

As part of our interest in the coordination chemistry of heavy Group 14 elements, we have synthesized complexes of general formula [(o-(Ph2P)C6H4)2SnClPh]AuX (X=Cl (2-Cl), X=Br (2-Br), and X=I (2-I)) in which the chlorostanane unit acts as a σ-acceptor ligand toward gold. The existence of a Au→Sn dative bond is evidenced by a trigonal bipyramidal geometry about the tin atom as well as a distorted square planar geometry about the gold center. While the measured Au–Sn bond distances are crystallographically indistinguishable in this series, theoretical investigations reveal that the strength of the Au→Sn interaction increases in the order 2-I<2-Br<2-Cl. These results suggest that the Au→Sn interaction is affected by the ligands around gold. Lastly, we also report the tripodal complex [(o-(Ph2P)C6H4)3SnCl]AuSnCl3 (4) in which the gold atom is concomitantly coordinated to a Z-type tin ligand and an X-type tin ligand.