Synthesis of anionic pentafluorophenyl platinum-silver acetylide complexes. Molecular structures of (NBu 4[Pt(C 6F 5) 2(μ-CCPh) 2Ag(PPh 3)] and (NBu 4) 2[{Pt(C 6F 52(μ-CCPh) 2Ag} 2(μ-dppe)

Abstract

Heterobinuclear alkynyl-bridged complexes (NBu 4)[Pt(C 6F 5) 2(μ-CCR) 2AgL] (R=1cr;Ph or tBu; L=1cr;PPh 3 or PEt 3) ( 1- 4) are obtained by treating the anionic tetranuclear platinum-silver derivatives (NBu 4) 2[Pt 2Ag 2(C 6F 5) 4(CCR) 4] (R=1cr;Ph or tBu) with PPh 3 or PEt 3 (molar ratio 1:2 or 1:4), whereas treatment with the bidentate 1,2-bis(diphenylphosphino) ethane (dppe) (molar ratio 1:1) gives tetranuclear complexes (NBu 4) 2[{Pt(C 6F 5) 2(μ-CCR) 2Ag} 2(μ-dppe)] (R=1cr;Ph 5; R=1cr; tBu 6). The structures of (NBu 4)[Pt(C 6F 5) 2(μ-CCPh) 2AgPPh 3]( 1) and (NBu 4) 2[{Pt(C 6F 5) 2(μ-CCPh) 2A} 2(μ-dppe)] ( 5) have been established by singlecrystal X-ray diffraction studies. In the solid state, the structure of the anion of complex 1 reveals that the two metal atoms [Pt⋯Ag 3.059(1) Å] are asymmetrically bridged by two phenylacetylide groups, each of which forms a σ-bond to platinum and a side-on π-bond to silver. The anion of compound 5, which possesses an inversion centre, is formed by two identical {Pt(C 6F 5) 2 (μ-CCPh) 2Ag} units connected through a dppe ligand. Each silver atom is asymmetrically π-bonded to each acetylide group and completes their trigonal coordination by bonding to a phosphorus atom of the dppe. 1H, 19F, 31P NMR data indicate that all complexes exhibit dynamic behaviour in solution.