A ternary Cu–Sn–S cluster complex—(NBu4)[Cu19S28(SnPh)12(PEt2Ph)3]

Abstract

Reaction of a mixture of CuCl, PhSnCl₃ and PEt₂Ph with S(SiMe₃)₂ in THF resulted initially in the unexpected synthesis of the ionic, mixed copper–tin sulfide cluster [Li(thf)₄][Cu₁₉S₂₈(SnPh)₁₂(PEt₂Ph)₃] in low yields. However, by adding NBu₄Cl to the reaction solutions we were able to selectively synthesize the structurally similar cluster ion in (NBu₄)[Cu₁₉S₂₈(SnPh)₁₂(PEt₂Ph)₃]. Structural characterization by single crystal X-ray analysis reveals that the cluster anions consist in principle of a copper sulfide core decorated by PhSn³⁺ groups. Although additional phosphine ligands are attached to copper atoms the clusters possess an open ‘Cu₃S₃’ face mostly protected by the [Li(thf)₄]⁺ and (NBu₄)⁺ counterions in the crystal structure. The cluster (NBu₄)[Cu₁₉S₂₈(SnPh)₁₂(PEt₂Ph)₃] displays near-infrared, temperature-dependent photoluminescence at ∼820–930 nm in the solid state, which is especially bright at temperatures below ∼100 K.