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 CHCHMe)

Abstract

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.