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

Six new copper(I) clusters, Et4N]2(MOS3)2Cu4(mu-SBu(t))2](1a: M = Mo; 1b: M = W), Et4N](MOS3)2Cu6(mu-SBu(t))3](2a: M = Mo; 2b: M = W) and Bu4N]2(MOS3)3Cu9(mu-SBu(t))3(mu3-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(mu-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 mu-SBu(t-) linkages. In the molecular structure of 3b, the SBu(t-) ligands act as mu- and mu3-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.