η5-Cyclopentadienyl and η5-methylcyclopentadienyl 1,2-bis(dimethylphosphino)ethane complexes of titanium(II). The crystal structure of Ti(C5H4Me)2(dmpe)

Abstract

The interaction of the titanium(II) complex trans-TiCl₂(dmpe)₂ with 2 equivalents of Na(C₅H₅) or Na(C₅H₄Me) in diethyl ether gives the dark orange cyclopentadienyl compounds Ti(C₅H₄R)₂(dmpe)(R = H or Me, dmpe = Me₂PCH₂CH₂PMe₂). These diamagnetic 18-electron species give n.m.r. spectra consistent with a bent metallocene structure, confirmed by the X-ray structure analysis of Ti(C₅H₄Me)₂(dmpe) for which Ti–P 2.533(6)Å(mean), Ti–C 2.310(5)–2.441 (6)Å, P–Ti–P 76.9(2)°, and centroid-Ti-centroid = 135.3(2)°. The cyclopentadienyl rings are very slightly tilted towards the dmpe ligand due to non-bonding contacts between the ring-bound methyl groups.