Platinum(0) Complexes with Alkynylphosphane Ligands

Abstract

Abstract The reactivity of the Pt 0 derivative [Pt 2 (dba) 3 ] (dba = trans , trans ‐dibenzylideneacetone) towards PPh 2 C≡CR [R = Ph, tolyl (Tol), C 5 H 4 N‐2] and PPh 2 C≡CPPh 2 (dppa) has been explored. Treatment of [Pt 2 (dba) 3 ] with PPh 2 C≡CR (8 equiv.) in THF gave the tetrahedral complexes [Pt(PPh 2 C≡CR) 4 ] [R = Ph ( 1 ), Tol ( 3 ), C 5 H 4 N‐2 ( 5 )], whereas reactions with a molar ratio of 1:4 afforded the binuclear derivatives [{Pt(PPh 2 C≡CR)(μ‐κ P :η 2 ‐PPh 2 C≡CR)} 2 ] [R = Ph ( 2 ), Tol ( 4 ) X‐ray, C 5 H 4 N‐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 PPh 2 C≡CPPh 2 afforded [Pt 2 (PPh 2 C≡CPPh 2 ) 2 (μ‐κ 2 PP′ ‐PPh 2 C≡CPPh 2 ) 3 ] ( 7 ), in which two “Pt(PPh 2 C≡CPPh 2 )” fragments are joined through three bridging dppa ligands (μ‐κ 2 PP′ ‐PPh 2 C≡CPPh 2 ). Attempts to crystallize 7 at –30 °C afforded crystals of [Pt 2 {PPh 2 C≡CP(O)Ph 2 } 2 (μ‐κ 2 PP′ ‐PPh 2 C≡CPPh 2 ) 3 ] ( 8 ) by oxidation of the free end of the terminal dppa ligands. The compound was characterized by X‐ray diffraction.