Multimetallic arrays: bi-, tri-, tetra-, and hexametallic complexes based on gold(I) and gold(III) and the surface functionalization of gold nanoparticles with transition metals.

Reaction of [AuCl(PPh(3))] with the zwitterion S(2)CNC(4)H(8)NH(2) yields [(Ph(3)P)Au(S(2)CNC(4)H(8)NH(2))]BF(4). Treatment of this species with NEt(3) and CS(2) followed by [AuCl(PPh(3))] leads to [{(Ph(3)P)Au}(2)(S(2)CNC(4)H(8)NCS(2))], which can also be obtained directly from [AuCl(PPh(3))] and KS(2)CNC(4)H(8)NCS(2)K. A heterobimetallic variant, [(dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2))Au(PPh(3))](+), can be prepared by the sequential reaction of [(dppm)(2)Ru(S(2)CNC(4)H(8)NH(2))](2+) with NEt(3) and CS(2) followed by [AuCl(PPh(3))]. Reaction of the same ruthenium precursor with [(dppm)(AuCl)(2)] under similar conditions yields the trimetallic complex [(dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2))Au(2)(dppm)](2+). Attempts to prepare the compound [(dppm)Au(2)(S(2)CNC(4)H(8)NH(2))](2+) from [(dppm)(AuCl)(2)] led to isolation of the known complex [{(dppm)Au(2)}(2)(S(2)CNC(4)H(8)NCS(2))](2+) via a symmetrization pathway. [{(dppf)Au(2)}(2)(S(2)CNC(4)H(8)NCS(2))](2+) was successfully prepared from [(dppf)(AuCl)(2)] and crystallographically characterized. In addition, a gold(III) trimetallic compound, [{(dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2))}(2)Au](3+), and a tetrametallic gold(I) species, [{(dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2))Au}(2)](2+), were also synthesized. This methodology was further exploited to attach the zwitterionic (dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2)) unit to the surface of gold nanoparticles, which were generated in situ and found to be 3.4 (+/-0.3) and 14.4 (+/-2.5) nm in diameter depending on the method employed. Nanoparticles with a mixed surface topography were also explored.