Rearrangement of a σ-2-(Cycloprop-2-enyl)vinyl- to an η³-Cyclopentadienylplatinum(II) Complex. Selective Protonolysis of the Platinum−Methyl Bond

The σ-2-(cycloprop-2-enyl)vinylplatinum(II) complex (PEt3)2Pt(Me)(CHCH-cyclo-C3HPh2) (5) was prepared and characterized by NMR spectroscopy and X-ray crystallography. Treatment of 5 with Bronsted acids results in selective splitting of the Pt−methyl bond to give chloro derivative (PEt3)2Pt(Cl)(CHCH-cyclo-C3HPh2) (6), or the rearranged η3-diphenylcyclopentadienyl cation 7+, depending on the acid employed. Formation of cation 7+ could also be accomplished by treatment of 6 with TlPF6. Monitoring the protonolysis reactions by NMR spectroscopy at −60 °C, however, showed no evidence for platinabenzene or platinabenzvalene intermediates.