Metals in organic syntheses. XI. 31P NMR and reactivity studies on the system trans-[PtCl(CO-n-hexyl)(PPh3)2]/SnCl2, an active intermediate in the catalytic hydroformylation of 1-hexene

Article abstract of DOI:10.1016/0022-328X(85)87240-5

The system trans-[PtCl(CO-n-hexyl)(PPh₃)₂]/SnCl₂ has been investigated by ³¹P NMR spectroscopy. In CD₂Cl₂ or acetone-d₆ solutions two species (in equilibrium with the starting Pt complex) are observed at low temperature: one set of signals is attributed to the complex trans-[Pt(SnCl₃)(CO-n-hexyl)(PPh₃)₂]; the other set does not show SnP coupling and it is tentatively attributed to a complex having chloride bridging the Pt and Sn metal centers. Formation of the complex trans-[Pt(SnCl₃)(CO-n-hexyl)(PPh₃)₂] is prevented when ethanol is added to the CD₃Cl₂ are acetone-d₆ solutions. Treatment of the CD₂Cl₂ or acetone-d₆ solution with molecular hydrogen give n-heptanal and hydroplatinum species; this reaction does not occur in the presence of ethanol, where only a complex having chloride bridging the Pt and Sn metal centers seems to be present. The result are discussed in connection with the catalytic cycle of olefin hydroformylation promoted by the [PtCl₂(PPh₃)₂]/SnCl₂ system.