Intermolecular Activation of C−X (X = H, O, F) Bonds by a Ti⋮CtBu Linkage

The transient titanium alkylidyne complex (PNP)Ti⋮C t Bu (PNP = N[2-P(CHMe 2 ) 2 -4-methylphenyl] 2 - ) can readily activate, in some cases regioselectively, the aromatic C−H bond of anisole and fluoro-substituted anisoles to generate titanium alkylidene complexes having a substituted aryl group. Intermolecular C−O bond activation occurs when perfluoroanisole reacts with (PNP)Ti⋮C t Bu to afford the disubstituted alkylidene methoxide (PNP)Ti C[ t Bu(C 6 F 5 )](OCH 3 ). Likewise, intermediate (PNP)Ti⋮C t Bu can also promote the intermolecular C−F activation of C 6 F 6 and CF 3 C 6 F 5 to generate disubstituted alkylidene fluorides (PNP)Ti [ t Bu(Ar F )](F) (Ar F = C 6 F 5, C 6 F 4 CF 3 ). In the case of Ar = C 6 F 4 CF 3, the product resulting from para -aryl C−F activation was isolated. For the latter two C−F bond activation reactions, mixtures of alkylidene rotamers exist in solution. Complexes resulting from C−H, C−O, and C−F (including the rotamers for the latter reaction) activation have been characterized by single-crystal X-ray diffraction methods.