A series of novel Mo(W)/Cu/S heterobimetallic clusters containing SBut− linkages. Synthesis, structure and spectroscopic characterisation

Abstract

Six new copper(I) clusters, [Et₄N]₂[{MOS₃}₂Cu₄(μ-SBu^t)₂] (1a: M = Mo; 1b: M = W), [Et₄N][{MOS₃}₂Cu₆(μ-SBu^t)₃] (2a: M = Mo; 2b: M = W) and [Bu₄N]₂[{MOS₃}₃Cu₉(μ-SBu^t)₃(μ₃-SBu^t)][I] (3a: M = Mo; 3b: M = W) have been prepared by the reactions of thiomolybdates and thiotungstates with CuSBu^t under various conditions. The [{MOS₃}₂Cu₄(μ-SBu^t)₂]²⁻ dianions in 1a and 1b represent the first examples of double butterfly-shaped Mo(W)/Cu/S clusters. Addition of more Cu atoms to 1a or 1b resulted in the formation of incomplete double cubane-like clusters 2a or 2b. Single crystal structural studies showed that the anions of 2a and 2b are formed in a mouth-to-mouth fashion by two incomplete cubanes [MOS₃Cu₃] (M = Mo, W) with three μ-SBu^t− linkages. In the molecular structure of 3b, the SBu^t− ligands act as μ- and μ₃-bridges which link three WOS₃Cu₃ incomplete cubane-like fragments. An iodide ion crystallises in the cavity defined by the three incomplete cubanes in 3b. The spectroscopic and electrochemical properties of all the clusters are also studied.