Platinum(0) Complexes with Alkynylphosphane Ligands

The reactivity of the Pt0 derivative [Pt2(dba)3] (dba = trans,trans‐dibenzylideneacetone) towards PPh2C≡CR [R = Ph, tolyl (Tol), C5H4N‐2] and PPh2C≡CPPh2 (dppa) has been explored. Treatment of [Pt2(dba)3] with PPh2C≡CR (8 equiv.) in THF gave the tetrahedral complexes [Pt(PPh2C≡CR)4] [R = Ph (1), Tol (3), C5H4N‐2 (5)], whereas reactions with a molar ratio of 1:4 afforded the binuclear derivatives [{Pt(PPh2C≡CR)(μ‐κP:η2‐PPh2C≡CR)}2] [R = Ph (2), Tol (4) X‐ray, C5H4N‐2 (6)], which were shown to be generated through the mononuclear complexes 1, 3 and 5 as intermediate species. An analogous reaction using 4 equiv. of PPh2C≡CPPh2 afforded [Pt2(PPh2C≡CPPh2)2(μ‐κ2PP′‐PPh2C≡CPPh2)3] (7), in which two “Pt(PPh2C≡CPPh2)” fragments are joined through three bridging dppa ligands (μ‐κ2PP′‐PPh2C≡CPPh2). Attempts to crystallize 7 at –30 °C afforded crystals of [Pt2{PPh2C≡CP(O)Ph2}2(μ‐κ2PP′‐PPh2C≡CPPh2)3] (8) by oxidation of the free end of the terminal dppa ligands. The compound was characterized by X‐ray diffraction. Tetrahedral Pt0 complexes [Pt(PPh2C≡CR)4], which evolve into binuclear derivatives [{Pt(PPh2C≡CR)(μ‐κP:η2‐PPh2C≡CR)}2] [R = Ph, tolyl, C5H4N‐2], and binuclear compounds stabilized by a (μ‐PPh2C≡CPPh2)3 triply bridging system have been prepared and fully characterized.