Novel diphosphine platinum cations: NMR and Mössbauer spectra and catalytic studies

Abstract

The reaction of PtCl 2(diphosphine) with mono and bidentate phosphines has been investigated by NMR spectroscopy. [Pt(diphosphine) (PMe 3) 2] 2+, [Pt(diphosphine) 2] 2+ and [Pt(( S, S)-bdpp)(( S, S)-chiraphos)] 2+ cations have been characterized by 31P NMR and conductivity measurements. The presence of tin(II) chloride promotes the formation of the complex cations. Evidence for coordination of the diphosphine in monodentate mode has benn obtained by NMR spectroscopy. The platinum species possessing a platinum-tin bond and ionic complexes with an SnCl 3 − counterion can easily be distinguished by 119Sn Mössbauer spectroscopy. Asymmetric hydroformylation of styrene with [Pt(( S, S)-bdpp) 2] 2+(SnCl 3 −) 2 as catalyst precursor gave chemo-, regio- and enantio-selectivities different from those obtained with the covalent PtCl(SnCl 3)(( S, S)-bdpp) as catalyst precursor.