Gold(I) Complexes with Bulky Phosphanes: A Dual Approach to Triplet Harvesting and Hydroamination Catalysis

Abstract

Two families of mononuclear gold(I) complexes featuring Au-chromophore units, with chromophores being carbazole (a), phenanthrene (b), or dibenzofuran (c), were synthesized. The Au(I) atoms are coordinated to two phosphanes, either $PMe_{2}Ar^{Xyl2}(Ar^{Xyl2} = 2,6-C_{6}H{_3}-(2,6-C_{6}H{3}-Me_{2})_{2})$ (P1) or the bulkier $PCyp_{2}Ar^{Xyl2}(Cyp = cyclopentyl)$ (P2). The photophysical properties of these complexes were extensively studied, with a particular focus on the effects of phosphane bulkiness and chromophore electron-donating capacity on triplet state quantum yields ($\Phi_{T}$). Nanosecond-laser flash photolysis measurements were employed to calculate $\Phi_{T}$. Time-dependent density functional theory (TD-DFT) calculations supported the absorption and emission assignments, providing insights into the electronic state gaps involved in photophysical processes and their relative populations. The parent complex AuCl (P2) in combination with ${NaBAr_{4}}^F$, as a chloride scavenger, served as an efficient catalyst for the hydroamination of a variety of alkynes and amines, under mild conditions and with low Au loading (0.1–0.2 mol %). Luminescent studies allowed us to check the active catalytic species.