Platinum(0) complexes with alkynylphosphane ligands

Abstract

The reactivity of the Pt 0 derivative [Pt 2(dba) 3] (dba = trans,trans-dibenzylideneacetone) towards PPh 2C≡CR [R = Ph, tolyl (Tol), C 5H 4N-2] and PPh 2C≡CPPh 2 (dppa) has been explored. Treatment of [Pt 2(dba) 3] with PPh 2C≡CR (8 equiv.) in THF gave the tetrahedral complexes [Pt(PPh 2C≡CR) 4] [R = Ph (1), Tol (3), C 5H 4N-2 (5)], whereas reactions with a molar ratio of 1:4 afforded the binuclear derivatives [{Pt(PPh 2C≡CR)(μ-κP:η 2-PPh 2C≡CR)} 2] [R = Ph (2), Tol (4) X-ray, C 5H 4N-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 2C≡CPPh 2 afforded [Pt 2(PPh 2C≡CPPh 2) 2(μ- κ 2PP'-PPh 2C≡CPPh 2) 3] (7), in which two "Pt(PPh 2C≡CPPh 2)" fragments are joined through three bridging dppa ligands (μ- κ 2PP'-PPh 2C≡CPPh 2). Attempts to crystallize 7 at -30 °C afforded crystals of [Pt 2{PPh 2C≡CP(O)Ph 2} 2(μ- κ 2PP'-PPh 2C≡CPPh 2) 3] (8) by oxidation of the free end of the terminal dppa ligands. The compound was characterized by X-ray diffraction. Tetrahedral Pt 0 complexes [Pt(PPh 2C≡CR) 4], which evolve into binuclear derivatives [{Pt(PPh 2C≡CR)(μ-κP: η 2-PPh 2C≡CR)} 2] [R = Ph, tolyl, C 5H 4N-2], and binuclear compounds stabilized by a (μ-PPh 2C≡CPPh 2) 3 triply bridging system have been prepared and fully characterized. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.