Dehydrogenation of hydrocarbons with metal-carbon multiple bonds and trapping of a titanium(II) intermediate.

Reacting (PNP)Ti[double bond, length as m-dash]CH(t)Bu(CH2(t)Bu) with 2,2'-bipyridine (bipy) in cyclohexane or heptane results in dehydrogenation, cleanly producing cyclohexene and 1-heptene, respectively, and a Ti(II) intermediate that is trapped by bipy to produce [(PNP)Ti(III)(CH2(t)Bu)(bipy˙(-))] (1). This titanium(ii) intermediate reduces the bipy ligand upon coordination to form a Ti(III) center, where the unpaired electron is antiferromagnetically coupled to the electron of the reduced [bipy˙(-)] π-radical moiety, giving an overall diamagnetic species. Complex 1 has been characterized by NMR and UV-vis spectroscopies as well as single crystal X-ray diffraction studies.