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 sp(3)-sp(3) coupling products (ethane and [NCN]Pt(OTf), 3) and an sp(2)-sp(3) 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)).