Methane activation and exchange by titanium-carbon multiple bonds

We demonstrate that a titanium-carbon multiple bond, specifically an alkylidyne ligand in the transient complex, (PNP)Ti≡C^(t)Bu (A) (PNP^− = N[2-P(CHMe_2)_(2)-4-methylphenyl]_2), can cleanly activate methane at room temperature with moderately elevated pressures to form (PNP)Ti=CHtBu(CH_3). Isotopic labeling and theoretical studies suggest that the alkylidene and methyl hydrogens exchange, either via tautomerization invoking a methylidene complex, (PNP)Ti=CH_(2)(CH_(2)^(t)Bu), or by forming the methane adduct (PNP)Ti≡C^(t)Bu(CH_4). The thermal, fluxional and chemical behavior of (PNP)Ti=CH^(t)Bu(CH_3) is also presented in this study