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

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 (N-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 trans-influencer than is the alkynyl,
but the alkynyl is more electron-releasing. These results suggest
that trans-influences in two-coordinate gold­(I) complexes
can be more than a simple matter of ligand donicity.