REACTIVITY OF A VINYLIDENETITANOCENE INTERMEDIATE WITH PROTIC AGENTS - SELECTIVE SYNTHESIS OF 1-ALKENYLTITANOCENE COMPOUNDS

A variety of proton donating substrates (ROH, H2O) react with the vinylidenetitanocene intermediate [Cp(2)*Ti=C=CH2] (3), which is formed in situ by thermolysis of Cp(2)*TiC(=CH2)CH2CH2 (4) or Cp(2)*Ti(CH=CH2)(CH3) (5), to yield vinyltitanium derivatives {Cp(2)*Ti(CH=CH2)(OR), R=CH3 (8a), C2H5 (8b), n-C3H7 (8c), i-C3H7 (8d), H (11)}. The formation and properties of other Cp(2)*Ti(CH=CH2)(X) derivatives (X = F (13a), Cl (13b), Br, (13c), NH2 (14)), formed directly from the corresponding Cp(2)*TiX(2) complexes and vinyllithium or by anion exchange from Cp(2)*Ti(CH=CH2)(Cl) (13b), are discussed in the light of the H-1 and C-13-NMR data. The structure of vinyltitanocenefluoride, Cp(2)*Ti(CH=CH2)F (13a), has been determined: monoclinic, space group P2(1)ln, lattice constants a = 8.628(5), b = 15.49(1), c = 15.23(1) Angstrom, beta = 100.28(5)degrees. The Ti-C(sigma) bond length is 2.098(6) Angstrom and the C(sigma)-Ti-F angle is 93.5(8)degrees. In the course of attempts to build up cationic [Cp(2)*TiCH=CH2](+) complexes from 4 Cp(2)*Ti(OSO2CF3)(Cl) (17) can be isolated as a subsequent product, characterised by X-ray structure determination.