The compounds [TiCl,(dmpe)R] (R = Me, CH,D, or Et; dmpe = Me,PCH,CH,PMe,) have been prepared. An X-ray crystal structure determination of [TiCl,(dmpe) Et] shows that the TiC -C a of the Ti-Et moiety is 86.3(6)". Variable-temperature n.m.r. studies show the molecule to be fluxional at room temperature. At-9 0 "C the n.m.r. spectra correspond to the structure found i rgle I the crystal and J(C-H) for the ethyl CH, hydrogens is 150.2 Hz. It is concluded that the ethyl group is bonded by a fi-CH,CH,-k system. The crystal structure of [TiCl,(dmpe) Me] has beer determined from X-ray and neutron diffraction data. The data show the methyl group to be distorted such that it is tilted with respect to the TiC vector and one hydrogen atom closely approaches the TI centre giving an angle for TiC -H of 93.5(2)* (neutron data). Variabletemperature n.m.r. studies show that [TiCl,(dmpe) R] (R = CH, or CH,D) are fluxional but provide * [ 1 ,2-Bis(dimethylphosphino)ethane]trichloro-(ethyl-Cu,H 8)titan~um and-(met hyl)titanium. SuppIementar~dutauvuiIahIe(No. SUP56535,6pp.): thermal parameters. See Instructions for Authors, J. Chem. SOC., Dalton Trans., 1986, Issue 1, pp. xvii-xx. Structure factors are available from the editorial office. of the literature in the light of these constraints led us to select the compounds [TiCl,(dmpe)R] [R = Et (2) or Me (3); dmpe = Me,PCHzCHzPMez]. The synthesis and characterisation of these compounds is described below. Preliminary reports of a part of these studies have Results The long-known' compound TiC1,Et (1) is an extremely airand moisture-sensitive liquid which decomposes steadily at room temperature. Hydrocarbon solutions at room temperature decompose more slowly. Compound (1) may be distilled in U~C U O but the vapour is photosensitive. Treatment of (1) with 1,2-bis(dimethyIphosphino)ethane (dmpe) gave black-red crystals of [TiCl,(dmpe)Et] (2). Compound (2) is also extremely air-and moisture-sensitive but it is considerably more thermally stable than (1) and the solid can be kept at room temperature. Solutions of (2) in toluene decompose steadily at room temperature yielding a dull-red insoluble powder. Crystals of [TiCl,(dmpe)Et] suitable for X-ray diffraction were prepared by slow crystallisation at-5 "C from toluene. It was essential to remove any traces of TiO, formed by contact with the glass. The complex [TiCl,(dmpe)Me] (3) was prepared by treatment of a light petroleum (b.p. 40-60 "C) solution of TiCI,Me* with dmpe at-1 5 "C. The orange-red precipitate was recrystallized from toluene as red-black crystals. These were extremely air-and moisture-sensitive but less thermally sensitive than the ethyl analogue (2). Solutions may be allowed to stand at room temperature for several days before decomposition becomes substantial. The decomposition product was a red powder identical in appearance and behaviour to that obtained from thermal decomposition of (2). Crystal Structures of(2) and(3).-The molecular structures of (2) and (3) were determined from X-ray data at room temperature C(3X)J an...
