Synthesis of anionic pentafluorophenyl platinum-silver acetylide complexes. Molecular structures of (NBu4)[Pt(C6F5)2(mu-C=CPh)2AgPPh3] and (NBu4)2[{Pt(C6F5)2(mu-C=CPh)2Ag}2(mu-dppe)]

Résumé

Heterobinuclear alkynyl-bridged complexes (NBu4)[Pt(C6F5)2(μ-CCR)2AgL] (R=1cr;Ph or tBu; L=1cr;PPh3 or PEt3) (1-4) are obtained by treating the anionic tetranuclear platinum-silver derivatives (NBu4)2[Pt2Ag2(C6F5)4(CCR)4] (R=1cr;Ph or tBu) with PPh3 or PEt3 (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 (NBu4)2[{Pt(C6F5)2(μ-CCR)2Ag}2(μ-dppe)] (R=1cr;Ph 5; R=1cr;tBu 6). The structures of (NBu4)[Pt(C6F5)2(μ-CCPh)2AgPPh3](1) and (NBu4)2[{Pt(C6F5)2(μ-CCPh)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(C6F5)2 (μ-CCPh)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. © 1993.