N-H group transfer and oxidative addition chemistry promoted by isolable bis(cyclopentadienyl)titanium sandwich complexes

Addition of propylenimine (2-methylaziridine) to the bis(cyclopentadienyl) titanium sandwich complexes, (η⁵-C₅Me ₄R)₂-Ti (R = iPr, SiMe₃), resulted in rapid [NH] group transfer followed by C-H activation of a cyclopentadienyl methyl group to yield the corresponding cyclometalated titanocene amido compounds. Exposure of these molecules to 4 atm of H₂ at 55°C resulted in hydrogenolysis of the metal-carbon bond to form the titanium amido hydride compounds, (η⁵-C₅Me₄R)₂- Ti(NH₂)H. Deuteriolysis with DCl gas confirmed exclusive cyclometalation from the positions adjacent to the isopropyl and trimethylsilyl substituent. Oxidative addition of the N-H bonds of amines has also been observed. Addition of NH₃ to either (η⁵-C ₅Me₄SiMe₃)₂Ti or (η⁵-C₅Me₄iPr)₂Ti yielded the corresponding titanocene amido hydrides along with the titanocene(III) amides, (η⁵-C₅Me₄R)₂TiNH₂, arising from formal deprotonation by unreacted sandwich from the putative titanocene ammonia complex.