Novel η3-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 complexes: 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 presented. In complex 2, in addition to two bridging chloride ligands a eta(3)-allyl group spans two titanium atoms with a Ti ... Ti separation of 2.908(1) Angstrom. The allyl bridge is symmetrical with each terminal carbon atom having a Ti-C distance of 2.154(6) Angstrom, while the central carbon atom is equidistant from the titanium atoms, Ti-C-cent, 2.430(6) Angstrom. Each Ti atom in 2 is further coordinated by a chelating dmpe ligand and a chloride ion. In the mononuclear complex 3 two eta(3)-allyl groups are bound to the Ti-III center and the coordination is completed by a chelating diphosphine ligand 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.