728895-87-2Relevant academic research and scientific papers
Synthesis of a base-free titanium imido and a transient alkylidene from a titanocene dinitrogen complex. Studies on Ti=NR hydrogenation, nitrene group transfer, and comparison of 1,2-addition rates
Hanna, Tamara E.,Keresztes, Ivan,Lobkovsky, Emil,Bernskoetter, Wesley H.,Chirik, Paul J.
, p. 3448 - 3458 (2008/10/09)
The synthesis and reactivity of the end-on bound dinitrogen complex [(η5-C5H3-1,3-(SiMe3)2)2Ti] 2(μ2,η1,η1-N 2) is described. The solid state structure of the dinitrogen compound reveals a weakly activated end-on bound N2 ligand with an N-N bond length of 1.164(5) A. Displacement of the N2 ligand by organic azides has been used to prepare monomeric, base-free titanocene imido complexes, (η5-C5H3-1,3-(SiMe3)2)2Ti=NR (R = SiMe3, 2,4,6-Me3-C6H2). While unreactive toward C-H bonds, the Ti-N linkage is readily hydrogenated and participates in group transfer reactions with unsaturated organic molecules such as carbon monoxide and benzophenone. Reaction of the N2 complex with Ph2CN2 allowed isolation of (η5-C5H 3-1,3-(SiMe3)2)2Ti(N2CPh2), which exists as a mixture of interconverting η2 and n1 isomers in solution. The diazoalkane complex also participates in imido-like reactivity, producing (η5-C 5H3-1,3-(SiMe3)2)2Ti(NHN=CPh2)H upon addition of H2. Changing the diazoalkane to Me3SiCHN 2 resulted in isolation of the double cyclometalated titanocene (η5-C5H3-η1-SiM 2CH2-3-SiMe3)2Ti, arising from facile intramolecular C-H activation of the cyclopentadienyl substituent by a transient titanocene alkylidene.
