Hexaplatinum Clusters with Carbonyl and Diphosphine Ligands and the Trapping of Mercury(0) and Thallium(I)

Hexaplatinum cluster complexes have been prepared by reduction of [PtCl 2 (SMe 2 ) 2 ] with NaBH 4 in the presence of CO and the diphosphine ligands Ph 2 P(CH 2 ) n PPh 2, n = 2 (dppe), 3 (dppp), 4 (dppb), 5 (dpppe), and 6 (dpph). The products are the closed cluster [Pt 6 (μ-CO) 6 (μ-dppe) 3 ], 2b, and the open cluster [Pt 6 (μ-CO) 6 (μ-dppp) 2 (dppp) 2 ], 9, but the reactions failed to give isolable products when n = 4−6. Cluster 9 can encapsulate mercury(0) or thallium(I) with loss of dppp to give the closed clusters [Pt 6 (μ 6 -Hg)(μ-CO) 6 (μ-dppp) 3 ], 10a, or [Pt 6 (μ 6 -Tl)(μ-CO) 6 (μ-dppp) 3 ] +, 11a, respectively. The Pt 6 (μ-CO) 6 (μ-dppp) 3 unit acts as a cryptand and evidence is presented that the cluster 10a must open to allow reaction with thallium(I) to give 11a . Reduction of [PtCl 2 (SMe 2 ) 2 ] with NaBH 4 in the presence of CO, the diphosphine ligands Ph 2 P(CH 2 ) n PPh 2, and mercury can give [Pt 6 (μ 6 -Hg)(μ-CO) 6 {μ-Ph 2 P(CH 2 ) n PPh 2 } 3 ], 10a − d, n = 3−6, respectively, directly, but clusters [Pt 6 (μ 6 -Hg)(μ-CO) 6 (CO) 2 {μ-Ph 2 P(CH 2 ) n PPh 2 } 2 ], 12, are also formed in some cases. Cluster 2b reacts with [Ph 3 PAu] + to give [Pt 6 (μ-CO) 6 (μ-dppe) 3 (μ 3 -AuPPh 3 ) 2 ] 2+ .