Assembly of silver(i)–copper(i) bimetallic thiolate complexes assisted by phenylacetylene stabilizers

Abstract

Ag^I/Cu^I bimetallic clusters have been widely reported, but synthesis of such clusters via simple self-assembly of heterometallic ions in air remains challenging due to the susceptibility of Cu^I ions to oxidation. In this study, protected by the phenylacetylene auxiliary ligand, we utilized [Cu(CH₃CN)₄]PF₆ in conjunction with the (ⁱPrSAg)_n polymer to form Ag(I)–Cu(I) oligomer precursors, serving as the starting point for constructing a new [Ag_11−xCu_x(ⁱPrS)₉(DPPM)₃](PF₆)₂ cluster (DPPM = bis(diphenylphosphino)methane, Ag_11−xCu_x, x = 5–9). When the (ⁱPrSAg)_n precursor was replaced by (^tBuSAg)_n, another cluster [Ag₂₁Cu₄S₂(^tBuS)₁₈(CH₃CN)₄](CH₃OH)₂(H₃O)(PF₆)₄ (Ag₂₁Cu₄) was obtained. By combining crystallographic data and electrospray ionization mass spectrometry (ESI-MS) results, the compositions and structures of these two new clusters were determined. Additionally, the optical physical properties of the luminescent Ag_11−xCu_x were investigated, showing red phosphorescence emission in both solid-state and solution phases. The solid-state phosphorescence quantum yield (QY) is 8%, with a lifetime of 7.2 μs. These findings suggest that phenylacetylene auxiliary ligands can effectively stabilize Cu^I ions and guide the assembly of silver-copper bimetallic thiolate motifs into new compounds under ambient conditions.