Synthesis and Structure of a CuI3S Cluster Unsupported by Other Bridging Ligands

The facile synthesis of a {LCuI}3(μ3-S) cluster supported by monodentate N-heterocyclic carbene ligands has been accomplished through an approach in which two-coordinate (NHC)­Cu+ centers are installed sequentially on a sulfido ligand. The reaction between (IPr)­CuCl (IPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene) and S­(SiMe3)2 yields (IPr)­Cu­(SSiMe3) (2). Treatment of 2 with [(IPr)­Cu­(NCMe)]­[BF4] produces the dicopper cluster [{(IPr)­Cu}2(μ-SSiMe3)]­[BF4] (3[BF4]), which undergoes subsequent reaction with (IPr)­CuF to afford [{(IPr)­Cu}3(μ3-S)]­[BF4] (1[BF4]) in high yield. The X-ray crystal structure of 1[BF4] establishes it as a rare example of a CuIn(μn-S)­Lm cluster, and the first that is not also supported by other bridging ligands.