"Gold(I) Complexes Bearing Mixed-Donor Ligands Derived from N-Heterocyclic Carbenes"

Eugene Y. Chia, Saira Naeem, Lionel Delaude, Andrew J. P. White, and James D. E. T. Wilton-Ely

Journal Cover
          source: Dalton Transactions
            year: 2011
          volume: 40
      first page: 6645
       last page: 6658
             doi: 10.1039/c0dt01613f

graphical abstract

Abstract: 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)Au2(SCNPh·IMes)]2+, while reaction of [L2(AuCl)2] with two equivalents of IMes·CSNPh results in [(L2){Au(SCNPh·IMes)}2]2+ (L2 = dppb, dppf, or dppa; dppb = 1,4-bis(diphenylphosphino)butane, dppf = 1,1'-bis(diphenylphosphino)ferrocene, dppa = 1,2-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, CNtBu). 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, [(Ph3P)Au(SCNPh·IMes)]PF6 and [Au(AgOTf)2(SCNPh·IMes)2]OTf were characterized crystallographically.

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