Protonolyses of (dfepe)Pt(Me)X (dfepe ) (C 2 F 5 ) 2 PCH 2 CH 2 P(C 2 F 5 ) 2 ; X ) O 2 CCF 3 , OSO 2 H, OSO 2 CF 3 , OSO 2 F) complexes in their respective neat acid solutions cleanly yield (dfepe)-Pt(X) 2 products with rates dependent on relative acid strengths. No (dfepe)Pt(Me)(X) 2 (H) + intermediates were observed by variable-temperature NMR in dichloromethane. The (perfluoroaryl)phosphine analogue (dfppe)Pt(Me) 2 (dfppe ) (C 6 F 5 ) 2 PCH 2 CH 2 P(C 6 F 5 ) 2 ) is much less resistant to protonolysis and rapidly converts to (dfppe)Pt(OTf) 2 in HOTf at 20 °C. Kinetic studies for protonolysis in CF 3 CO 2 H(D) and CF 3 SO 3 H(D) solvents were carried out. Examination of ionic strength and chloride anion effects in trifluoroacetic acid indicate that prior association of anion to (dfepe)Pt(Me)X systems is not kinetically important. k H /k D values were obtained from competitive protonolysis studies (CF 3 CO 2 H, 9 ( 2 (20 °C); H 2 SO 4 , 7 ( 2 (100 °C); CF 3 SO 3 H, 2.7 ( 0.7 (100 °C)). In the case of CF 3 CO 2 H, separate kinetic runs in protio and deuterio acids gave a lower k H /k D value of 3.6(4). The data obtained in these studies do not differentiate between limiting S E 2 and S E (oxidative) protonolysis mechanisms.

An extension of prior protonolysis studies of platinum−carbon bonds to Pt−aryl bonds is reported. The protolytic stability of (dfepe)Pt(Ph)(O2CCF3) (dfepe = (C2F5)2PCH2CH2P(C2F5)2) in trifluoroacetic acid is found to be much less than (dfepe)Pt(Me)(O2CCF3), indicating that a concerted SE2 protonolysis mechanism is most likely operative in these electron-poor platinum systems. VT NMR experiments show that benzene coordination to the (dfepe)Pt2+ center in neat fluorosulfonic acid to form (dfepe)Pt(η6-C6H6)2+ at −80 °C is competitive with benzene dissociation in this weakly coordinating medium.