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

Abstract

Reacting (PNP)TiCH^tBu(CH₂^tBu) 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^tBu)(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.