The Reaction of Alkenes with Triangulo-Clusters [Pt3(μ-CO)3(PR3)3]

The reactions of the cluster complexes [Pt3(μ-CO)3L3], where L=PPh3 1a, PPh2Bz 1b and PCy3 1c, with activated mono-olefins have been studied under preparative and equilibrium conditions. At low temperature the olefins react quantitatively giving the adducts [Pt3(μ-CO)3L3(olefin)] (olefin=trans-dicyanoethene, DCE 2a–2c, maleic anhydride, MA 3a–3c). The stereo-chemistry of these unstable clusters has been deduced from low temperature 31P, 13C, 195Pt-NMR and I.R. spectra. At higher temperature these adducts in presence of excess of olefin convert quantitatively to stable mononuclear Pt(0) complexes [Pt(CO)L(olefin)] (olefin=DCE 4a–4c, MA 5a–5c, maleimide, MI 6a–6c and 1–4-naphthoquinone, NQ 7a, 7c).