Mechanistic Study of Competitive sp3-sp3 and sp2-sp3 Carbon−Carbon Reductive Elimination from a Platinum (IV) Center and the Isolation of a C−C Agostic Complex

The addition of methyl triflate to an [NCN]PtCH3 pincer complex 1 ([NCN] = 2,6-bis(diethylaminomethyl)phenyl) results in kinetically controlled competitive reductive eliminations to generate both sp3-sp3 coupling products (ethane and [NCN]Pt(OTf), 3) and an sp2-sp3 coupling product, [[NC(CH3)N]PtCH3][OTf] (4). The last is a cationic complex that could either be formulated as an arenium species or, more likely, as a C−C agostic complex. The addition of CD3OTf to 1 affords 3, CH3CD3, and 4-d 3, with the deuterated label in 4-d 3 distributed between the arene methyl group and the platinum-bound methyl group, implicating the intermediacy of the five coordinate intermediate [[NCN]Pt(CH3)(CD3)]+ (I-d 3).