Structural Investigations of Platinum(II) Styrene and Styryl Complexes and Mechanistic Study of Vinylic Deprotonation

The X-ray structures of the π-complex [Pt(PNP)(CH2CHPh)](BF4)2 and the σ-complex [Pt(PNP)((E)-CHCHPh)]BF4 are reported (PNP = 2,6-bis(diphenylphosphinomethyl)pyridine). The styrene complex undergoes vinylic deprotonation by reaction with the weakly basic nucleophiles ROH (R = Me, Et, H), which was monitored by 1H and 31P NMR. The mechanistic pathway includes nucleophilic addition of the oxygen donor nucleophiles to the coordinated styrene. The resulting addition products [Pt(PNP)(CH2CHPhOR)]BF4 transformed to the styryl complex only when protons are present. Similarly, the related 1-vinylnaphthalene complex [Pt(PNP)(CH2CHC10H7)](BF4)2 undergoes vinylic deprotonation in the presence of methanol, forming the corresponding σ-complex [Pt(PNP)((E)-CHCHC10H7)]BF4.