Novel η3-allyl complexes of titanium

Treatment of TiCl4(dmpe) (1a) and TiCl4(depe) (1b) with two equivalents of C3H5MgCl in toluene at −30°C affords two novel allyl–titanium complexes: a dinuclear mixed-valent Ti25+ species Ti2(μ-Cl)2Cl2(dmpe)2(μ2-η3-C3H5) (2) and a mononuclear TiIII complex, TiCl(depe)(η3-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 η3-allyl group spans two titanium atoms with a Ti…Ti separation of 2.908(1) Å. The allyl bridge is symmetrical with each terminal carbon atom having a Ti–C distance of 2.154(6) Å, while the central carbon atom is equidistant from the titanium atoms, Ti–Ccent, 2.430(6) Å. Each Ti atom in 2 is further coordinated by a chelating dmpe ligand and a chloride ion. In the mononuclear complex 3 two η3-allyl groups are bound to the TiIII 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) Å.