Synthesis, structure, and reactions of a copper-sulfido cluster comprised of the parent CuS unit: {(NHC)Cu}(μ-S).

The synthesis of the first CuI2(μ-S) complex, {(IPr*)Cu}(μ-S) (IPr* = 1,3-bis(2,6-(diphenylmethyl)-4-methylphenyl)imidazol-2-ylidene; ), has been accomplished three synthetic routes: (1) salt metathesis between (IPr*)CuCl and NaS; (2) silyl-deprotection reaction between (IPr*)Cu(SSiMe) and (IPr*)CuF; and (3) acid-base reaction between (IPr*)Cu(SH) and (IPr*)Cu(O Bu). The X-ray crystal structure of exhibits two two-coordinate copper centers connected by a bent Cu-S-Cu linkage. Application of these synthetic routes to analogous precursors containing the sterically smaller ligand IPr (1,3-bis(2,6-di-isopropylphenyl)imidazol-2-ylidene), in place of IPr*, resulted in the formation of a transient product proposed as {(IPr)Cu}(μ-S) (), which decomposes quickly in solution. The instability of probably results from the insufficient steric protection provided by IPr ligands to the unsaturated Cu(μ-S) core; in contrast, is stable both in solution and solid state for weeks. The nucleophilic sulfido ligand in reacts with haloalkyl electrophiles (benzyl halides and dibromoalkanes) with formation of C-S bonds, affording (IPr*)Cu(SCHPh) and cyclic thioethers, respectively.