Ligand-based control of nuclearity in (NHC)gold(<scp>i</scp>) sulfides

N-Heterocyclic carbene (NHC) ligands support gold(I) sulfide complexes of varying nuclearity and charge. For sterically undemanding ligands, gold(I) chlorides react with sulfide to form trigold μ3-sulfido cations as the first observed products. The ligand IMes [1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] supports a monomeric cation, whereas the ICy-(1,3-dicyclohexylimidazol-2-ylidene-) supported cation crystallises as a dimer linked through an aurophilic interaction. The more sterically demanding IDipp [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] supports a terminal hydrosulfide, a (μ-hydrosulfido)digold cation, and a μ3-sulfido cation. Use of the expanded-ring NHC 7Dipp [1,3-bis(2,6-diisopropylphenyl)-4,5,6,7-tetrahydro-1,3-diazepin-2-ylidene] allows the isolation of a neutral digold sulfide.