Luminescent Au(III)-M(I) (M = Cu, Ag) Aggregates Based on Dicyclometalated Bis(alkynyl) Gold Anions†

The syntheses and structures of a series of complexes based on the C^∧C-chelated Au(III) unit (C^∧C = 4,4'-bis(t-butyl) 2,2'-biphenyl-1,1'-diyl) are reported, namely, [{(C^∧C)Au(C≡CBu)₂}₂M₂], (C^∧C)Au(C≡CR)(C≡NXyl), and [{(C^∧C)Au(C≡CR)₂}{M(C≡NXyl)}] (M = Ag, Cu; R = Bu, C₆H₄Bu-4, C₆H₄OMe-4; Xyl = 3,5-Me₂C₆H₃). The X-ray structures reveal a broad range of dispositions determined by the different coordination modes of Ag(I) or Cu(I). The complexes are bright photoemitters in the solid state and in poly(methyl methacrylate) (PMMA) films. The photoluminescence is dominated by ³IL(C^∧C) transitions, with indirect effects from the rest of the molecules, as supported by theoretical calculations. This work opens up the possibility of accessing Au(III) carbon-rich anions to construct photoluminescent aggregates.