Preparation and properties of some chlorotitanium carboxylates. X-Ray crystal and molecular structures of [{TiCl 3 (O 2 CCMe 3 )} 3 ] and [Ti 2 Cl 7 (O 2 CR)(RCO 2 H)](R =p-ClC 6 H 4 or CHCHMe)

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, CHCHPh or CHCHMe). 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 P, R= 0.059 for 3718 observed [I/σ(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 P, R= 0.078 for 1727 observed [I/σ(I) > 2.0] reflections} and 3(R = CHCHMe){triclinic space group, P, R= 0.070 for 1219 observed [I/σ(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.