198063-57-9Relevant academic research and scientific papers
Early-transition-metal ketenimine complexes: Synthesis, reactivity, and structure of ketenimine-containing titanocene and zirconocene complexes
Fandos, Rosa,Lanfranchi, Maurizio,Otero, Antonio,Pellinghelli, María Angela,Ruiz, M. José,Teuben, Jan H.
, p. 5283 - 5288 (1997)
Reaction of Cp2M(PMe3)2 complexes (M = Ti, Zr; Cp = η5-C5H5) with the N-(p-tolyl)-diphenylketenimine Ph′N=C=CPh2 (Ph′ = p-MeC6H4) in a 1:1 molar ratio affords the ketenimine-containing metallocene derivatives Cp2M(η2-(C,N)-Ph′N=C=CPh2)(PMe 3) (M = Ti (1); Zr (2)). The ketenimine ligand reacts in the same way with the Cp*2M species (Cp* = η5-C5Me5) generated from the reduction of the corresponding Cp*2MCl2 complexes with LitBu (1:2 molar ratio) to give the related complexes Cp*2M(η2-(C,N)-Ph′N=C=CPh2) (M = Ti (3); Zr (4)). The molecular structure of 3 shows a titanium atom bonded to two η5-cyclopentadienyl rings and a η2 -(C,N)-bonded ketenimine ligand. Reaction of Cp*2Ti with the ketenimine ligand in a 1:2 molar ratio gives 1,1,5,5-tetraphenyl-3-(p-tolyl)-2-(p-toluidino)-3-aza-1,4-pentadiene, which probably results from the coupling, followed by hydrolysis, of two ketenimine molecules coordinated to one titanocene moiety. Protonation of 3 with Et3NHCl or H2O (1:1 molar ratio) affords the intermediate species Cp*2Ti(X)(η2-(C,N)-Ph′N=C(H)-CPh 2) (X - Cl (5); OH (6)), which on hydrolysis evolves to give the enamine Ph′N(H)-CH=CPh2 as the final product. Finally, 3 reacts reversibly with H2 to give the hydride enamidate complex Cp*2Ti(H)(η1-Ph′N-CH-CPh2) (7). The structures of the different compounds have been determined by IR and NMR spectroscopic methods.
