Early-Transition-Metal Ketenimine Complexes:  Synthesis, Reactivity, and Structure of Ketenimine-Containing Titanocene and Zirconocene Complexes

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)(PMe3) (M = Ti (1); Zr (2)). The ketenimine ligand reacts in the s...

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Veröffentlicht in:Organometallics 1997-11, Vol.16 (24), p.5283-5288
Hauptverfasser: Fandos, Rosa, Lanfranchi, Maurizio, Otero, Antonio, Pellinghelli, María Angela, Ruiz, M. José, Teuben, Jan H
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Sprache:eng
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Zusammenfassung: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)(PMe3) (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) CPh2) (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.
ISSN:0276-7333
1520-6041
DOI:10.1021/om970568p