N-heterocyclic carbenes as effective ligands for the preparation of stabilized copper- and silver-t-butylthiolate clusters.

The ligation of N-heterocyclic carbenes (NHCs) to [CuS(t)Bu] and [AgS(t)Bu] was developed as an alternative to PR3 ligands as solubilizing reagents for these coordination polymers in order to form polynuclear copper and silver t-butylthiolate clusters. 1,3-Di-isopropylbenzimidazol-2-ylidene ((i)Pr2-bimy) and 1,3-di-isopropyl-4,5-dimethylimidazol-2-ylidene ((i)Pr2-mimy) were ligated to [CuS(t)Bu] and [AgS(t)Bu] forming [Cu4(S(t)Bu)4((i)Pr2-bimy)2] 1, [Cu4(S(t)Bu)4((i)Pr2-mimy)2] 2, [Ag4(S(t)Bu)4((i)Pr2-bimy)2] 5 and [Ag5(S(t)Bu)6][Ag((i)Pr2-mimy)2] 6. For comparison, the trialkyl phosphines P(n)Pr3 and P(i)Pr3 were also used to solubilize [AgS(t)Bu] and [CuS(t)Bu] to form copper and silver t-butylthiolate clusters. [Cu4(S(t)Bu)4(P(n)Pr3)2] 3, [Cu4(S(t)Bu)4(P(i)Pr3)2] 4, [Ag4(S(t)Bu)4(P(n)Pr3)2] 7 and [Ag6(S(t)Bu)6(P(i)Pr3)2] 8 were thus formed upon reaction with [CuS(t)Bu] and [AgS(t)Bu]. The synthesized complexes have been characterized via spectroscopic and crystallographic methods. The molecular structures of the clusters, which can vary according to the ligand type, are described.