Intermolecular activation of C-X (X = H, O, F) bonds by a TiCtBu linkage

The transient titanium alkylidyne complex (PNP)(TiCBu)-Bu-t (PNP = N[2-P(CHMe2)(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)(TiCBu)-Bu-t to afford the disubstituted alkylidene methoxide (PNP)TiC[Bu-t(C6F5)](OCH3). Likewise, intermediate (PNP)(TiCBu)-Bu-t can also promote the intermolecular C-F activation of C6F6 and CF3C6F5 to generate disubstituted alkylidene fluorides (PNP)Ti[Bu-t(Ar-F)](F) (Ar-F = C6F5, C6F4CF3). In the case of Ar = C6F4CF3, 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.