Gold(I) complexes bearing mixed-donor ligands derived from N-heterocyclic carbenes

The new 2-phenylthiocarbamoyl-1,3-dimesitylimidazolium inner salt (IMes.CSNPh) reacts with [AuCl(L)] in the presence of NH4PF6 to yield [(L)Au(SCNPh.IMes)]+(L = PMe3, PPh3, PCy3, CNBut). The carbene-containing precursor [(IDip) AuCl] reacts with IMes.CSNPh under the same conditions to afford the complex [(IDip)Au(SCNPh.IMes)](+) (IDip = 1,3-bis(2,6-diisopropylphenyl) imidazol-2-ylidene). Treatment of the diphosphine complex [(dppm)(AuCl)(2)] with one equivalent of IMes.CSNPh yields the digold metallacycle, [(dppm)Au-2(SCNPh.IMes)](2+), while reaction of [L-2(AuCl)(2)] with two equivalents of IMes.CSNPh results in [(L-2){Au(SCNPh.IMes)}(2)](2+) (L2 = dppb, dppf, or dppa; dppb = 1,4-bis(diphenylphosphino)butane, dppf = 1,1'-bis(diphenylphosphino) ferrocene, dppa = 1,4-bis(diphenylphosphino)acetylene). The homoleptic complex [Au(SCNPh.IMes)(2)] is formed on reaction of [AuCl(tht)] (tht = tetrahydrothiophene) with two equivalents of the imidazolium-2-phenylthiocarbamoyl ligand. This product reacts with AgOTf to yield the mixed metal compound [AuAg(SCNPh.IMes)(2)](2+). Over time, the unusual trimetallic complex [Au(AgOTf)(2)(SCNPh.IMes)(2)](+) is formed. The sulfur-oxygen mixed-donor ligands IMes.COS and SIMes.COS (SIMes = 1,3-bis(2,4,6-trimethylphenyl) imidazolin-2-ylidene) were used to prepare [(L)Au(SOC.IMes)](+) and [(L)Au(SOC.SIMes)](+) from [(L)AuCl] (L = PPh3, (CNBu)-Bu-t). The bimetallic examples [(dppf){Au(SOC.IMes)}(2)](2+) and [(dppf){Au(SOC.SIMes)}(2)](2+) were synthesized from the reaction of [(dppf)(AuCl)(2)] with the appropriate ligand. Reaction of [(tht)AuCl] with one equivalent of IMes.COS or SIMes.COS yields [Au(SOC.IMes)(2)](+) and [Au(SOC.SIMes)(2)](+), respectively. The compounds [(Ph3P)Au(SCNPh.IMes)]PF6, [(Cy3P)Au(SCNPh.IMes)]PF6 and [Au(AgOTf)(2)(SCNPh.IMes)(2)]OTf were characterized crystallographically.