Synthesis, structure, and electrochemical characteristics of a homologous series of gold(I) complexes featuring phosphine and phosphido–borohydride ligands.

A homologous series of linear, mononuclear gold(I) phosphine/phosphido-borohydride complexes, encompassing [Au(PR₃)₂]⁺ 1, [Au(PR₃)(PR₂BH₃)] 2 and [Au(PR₂BH₃)₂]^– 3 (R = tBu, Ad), has been prepared and structurally characterized. Strong intramolecular dispersion interactions are evident in the complexes with Ad-substituted ligands, which adopt eclipsed conformations in the solid state exclusively while there is no clear preference for the tBu-substituted analogues. Despite the disparate donor properties of the phosphine and phosphido-borohydride ligands, there are no statistically significant differences in Au–P bond length (≈2.33 Å) across the series. This difference is, however, manifested in the redox characteristics of the gold(I) complexes, which are more readily oxidized in the order 1 < 2 < 3.