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, (eta(5)-C5Me4R)(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 H-2 at 55 degrees C resulted in hydrogenolysis of the metal-carbon bond to form the titanium amido hydride compounds, (eta(5)-C5Me4R)2Ti(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 (eta(5)-C5Me4SiMe3)(2)Ti or (eta(5)-C(5)Me(4)iPr)(2)Ti yielded the corresponding titanocene amido hydrides along with the titanocene(III) amides, (eta(5)-C5Me4R)(2)TiNH2, arising from formal deprotonation by unreacted sandwich from the putative titanocene ammonia complex. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)