Vinyltitanium complexes containing the [2-(N,N-dimethylamino)ethyl]tetramethylcyclopentadienyl ligand Cp-*N. Generation and reactivity of the vinylidene intermediate [(Cp-*N)(Cp*)Ti=C=CH2] (Cp-*N=eta(5)-C5Me4(CH2)(2)NMe2, Cp*=eta(5)-C5Me5)

The reaction of [CpTiCl2](n) and Cp*TiCl2(thf) with Cp*Li-N (Cp*(N), C5Me4CH2CH2NMe2; Cp*, C5Me5) leads to Cp*(CpTiCl)-Cp-N(7) and Cp*Cp-N*TiCl(8), respectively. The monochlorides are oxidized by PbCl2 to give Cp*(CpTiCl2)-Cp-N (9) and Cp*Cp-N*TiCl2(10). The molecular structures of 7 and 10 have been determined by X-ray diffraction analysis, which reveals a chelating bonding mode of the Cp*(N)-ligand in 7 (Ti-N, 2.437(3) Angstrom) and noncoordination of the NMe2 group in 10. The fulvene complex Cp*(N)(C5Me4CH2)TiCH=CH2 (18) and the titanacyclobutane Cp*Cp-N*TiCH2CH2C=CH2 (14), respectively, are formed under mild conditions via the titanocenevinylidene intermediate [Cp*Cp-N*Ti=C=CH2] (17), generated by alpha-H transformation from the vinyl complexes Cp*Cp-N*Ti(CH=CH2)(CH3) (15) and Cp*Cp-N*Ti(CH=CH2)(2) (12). The formation of 14 is suggested to be influenced by the nitrogen-containing side chain in the Cp*(N)-ligand. A stabilization of 17 by intramolecular Ti-N coordination is not observed under the reaction conditions. Intermolecular trapping of 17 with transition metal carbonyls M(CO)(6) leads to the heterobinuclear titanaoxetanes Cp*Cp-N*TiOC(=M(CO)(5))C = CH2 (21, M = Cr (a), W (b)).