PREPARATION AND PROPERTIES OF SOME CHLOROTITANIUM CARBOXYLATES - X-RAY CRYSTAL AND MOLECULAR-STRUCTURES OF [(TICL3(O2CCME3))3] AND [TI2CL7(O2CR)(RCO2H)] (R = P-CLC6H4 OR CH = CHME)

Reactions of TiCl4 with carboxylic acids yield the trichloro(carboxylate) compounds [TiCl3(O2CR)] (R = Ph, p-MeC6H4, o-MeC6H4, 2,4,6-Me3C6H2, CMePh2, CHMe2, Me3C 1, C9H6N, CH = CHPh or CH = CHMe). The air-sensitive pivalate 1 is trimeric from crystal-structure analysis, with all carboxylates symmetrically bridging between two Ti atoms, and with one double and one triple bridging Cl {triclinic, space group P1BAR, R = 0.059 for 3718 observed [I/-sigma-(I) > 3.0] reflections}. Spectroscopic data suggest similar carboxylate bonding modes in the remaining compounds. Some reactions of the [TiCl3(O2CR)] compounds are described. Under more moderate conditions intermediates of composition [Ti2Cl7(O2CR)(RCO2H)] are obtained. Single-crystal X-ray analyses have been obtained for two such products, 2 (R = p-ClC6H4) {triclinic, space group P1BAR, R = 0.078 for 1727 observed [I/-sigma-(I) > 2.0] reflections} and 3 (R = CH = CHMe) {triclinic space group, P1BAR, R = 0.070 for 1219 observed [I/-sigma-(I) > 2.0] reflections}. They show similar structures, with each having a carboxylate anion bridging a bent Ti2Cl6 unit, and the sixth position of the octahedral titanium atom occupied by Cl and the co-ordinated neutral acid molecule.