INTRAMOLECULAR AND INTERMOLECULAR C-H ACTIVATION AT A CATIONIC PT-II CENTER

Syntheses and C-H bond activation reactions of the novel electrophilic Pt-II complexes [(tmeda)Pt(CH3)(OEt2)][BArf], [(tmeda)Pt(CH3) (THF)] [BArf], and [(tmeda)Pt(CH3)(NC5F5)] [BArf] are described {[BArf](-) = [(3,5-C6H3(CF3)(2))(4)B](-)} (tmedais N,N,N',N'-tetramethylethylenedia mine). [(tmeda)Pt(CH3)(OEt2)][BArf] and [(tmeda)Pt(CH3)(THF)][BArf] ar e unstable at room temperature, yielding methane and the Fischer carbe ne Pt-II hydrides, [(tmeda)Pt(=C(CH3) (OCH2CH3))(H)] [BArf] and [(tmed a)Pt(=CCH2CH2CH2O) (H)] [BArf]. The methane liberated from [(tmeda)Pt( CH3) (OEt2-d(10))] [BArf] consists of an isotopomeric mixture, (CH4, C H3D, CH2D2, and CHD3), indicating a multiple H/D exchange reaction fol lowing the C-D activation and prior to methane loss. [(tmeda)Pt(CH3) ( THF-d(8))][BAr] liberates CH4 and CH3D. Methane-C-13, cyclohexane, tol uene, and benzene react with [(tmeda)Pt(CH3) (NC5F5)][BArf] to yield m ethane and new organoplatinum complexes. Deuterated alkanes and arenes react with [(tmeda)Pt(CH3) (NC5F5)] [BArf] to give a mixture of metha ne isotopomers. The relevance of these results to the oxidation of alk anes by aqueous platinum complexes is discussed. (C) 1998 Elsevier Sci ence S.A.