Synthesis and Photophysical Properties of Au(III)-Ag(I) Aggregates

Cyclometalated gold(III) complexes of the type (C∧N∧C)AuX [HC∧N∧CH = 2,6-bis(4-Bu^tC₆H₄)pyrazine; 2,6-bis(4-Bu^tC₆H₄)pyridine, or 2,6-bis(4-Bu^tC₆H₄)4-Bu^tpyridine; X = CN, CH(COMe)₂, or CH(CN)₂] have been used as building blocks for the construction of the first family of Au^III/Ag^I aggregates. The crystal structures of these aggregates reveal the formation of complex architectures in which the Ag⁺ cations are stabilized by the basic centers present on each of the Au precursors. The photophysical properties of these aggregates are reported. Compared to mononuclear pincer complexes, a general red-shift and an increase in the emission intensity are observed. In agreement with DFT calculations, the lowest energy absorption and the emission are assigned to ¹IL(C∧N∧C) and ³IL(C∧N∧C) transitions dominated by the HOMO and the LUMO orbitals.