Azido, Triazolyl, and Alkynyl Complexes of Gold(I): Syntheses, Structures, and Ligand Effects

Abstract

Gold­(I) triazolyl complexes are prepared in [3 + 2] cycloaddition reactions of (tertiary phosphine)­gold­(I) azides with terminal alkynes. Seven such triazolyl complexes, not previously prepared, are described. Reducible functional groups are accommodated. In addition, two new (<i>N</i>-heterocyclic carbene)­gold­(I) azides and two new gold­(I) alkynyls are described. Eight complexes are crystallographically authenticated; aurophilic interactions appear in one structure only. The packing diagrams of gold­(I) triazolyls all show intermolecular hydrogen bonding between N-1 of one molecule and N-3 of a neighbor. This hydrogen bonding permeates the crystal lattice. Density-functional theory calculations of (triphenylphosphine)­gold­(I) triazolyls and the corresponding alkynyls indicate that the triazolyl is a stronger <i>trans</i>-influencer than is the alkynyl, but the alkynyl is more electron-releasing. These results suggest that <i>trans-</i>influences in two-coordinate gold­(I) complexes can be more than a simple matter of ligand donicity