Novel eta(3)-allyl complexes of titanium

Treatment of TiCl4(dmpe) (1a) and TiCl4(depe) (1b) with two equivalents of C3H5MgCl in toluene at -30 degrees C affords two novel allyl-titanium compl exes: a dinuclear mixed-valent Ti-2(5+) species Ti-2(mu-Cl)(2)Cl-2(dmpe)(2) (mu(2)-eta(3)-C3H5) (2) and a mononuclear Ti-III complex, TiCl(depe)(eta(3) -C3H5)(2) (3). Syntheses and crystal structures of 1b, 2 and 3 are presente d. In complex 2, in addition to two bridging chloride ligands a eta(3)-ally l group spans two titanium atoms with a Ti ... Ti separation of 2.908(1) An gstrom. The allyl bridge is symmetrical with each terminal carbon atom havi ng a Ti-C distance of 2.154(6) Angstrom, while the central carbon atom is e quidistant from the titanium atoms, Ti-C-cent, 2.430(6) Angstrom. Each Ti a tom in 2 is further coordinated by a chelating dmpe ligand and a chloride i on. In the mononuclear complex 3 two eta(3)-allyl groups are bound to the T i-III center and the coordination is completed by a chelating diphosphine l igand and one chloride ion. The Ti-C distances in 3 vary from 2.286(3) to 2 .478(3) Angstrom. (C) 2000 Elsevier Science S.A. All rights reserved.