Gold(I) Complexes with Bulky Phosphanes

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 PMe2ArXyl2 (ArXyl2 = 2,6-C6H3-(2,6-C6H3-Me2)2) (P1) or the bulkier PCyp2ArXyl2 (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 (ΦT). Nanosecond-laser flash photolysis measurements were employed to calculate ΦT. 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 AuClP2 in combination with NaBAr4F, 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.