TITANIUM OXO CARBOXYLATE COMPOUNDS - CRYSTAL AND MOLECULAR-STRUCTURES OF [(TICL2(O(2)CET)(ETCO2H)2O] AND [TI3CL3O2(O(2)CET)(5)] AND AN UNUSUAL QUANTITATIVE CONVERSION OF A TI2O TO A TI3O2 OXO DERIVATIVE

Reaction of TiCl4 with alkyl carboxylic acids RCO(2)H (R = Me, Et or Bu(t)) using a 1:1 (Ti:acid) molar ratio at 0 degrees C yielded the dinuclear chloro,carboxylates [Ti2Cl7(O(2)CR) (RCO(2)M)] (R = Et or Bua(t)). When a 1:2.5 ratio is used at 25 degrees C oxygen abstraction occurs to yield [{TiCl2(O(2)CR)(RCO(2)H)}O-2] (R = Me, Et or Bu(t)). When R = Et another product, [Ti2Cl3O(O(2)CEt)(3)(EtCO(2)H)], was also obtained. At 40-70 degrees C the oxo compounds (R = Et or Bu(t)) decompose quantitatively to form the trinuclear species [Ti3Cl3O2(O(2)CR)(5)], but the compound with R = Me remains unchanged up to 110 degrees C. The co-ordinated acid in [{TiCl2-(O(2)CR)(RCO(2)H)}O-2] is displaced by tetrahydrofuran (thf) to yield [{TiCl2(O(2)CR)(thf)}O-2] (R = Me, Et or Bu(t)), and;in contrast to the former, these species are stable up to 110 degrees C. The crystal structures of [{TiCl2(O(2)CEt) (EtCO(2)H)}O-2] and [Ti3Cl3O2(O(2)CEt)(5)] have been determined, and show [Ti(mu-O)(mu-O(2)CR)(2)Ti] and [Ti-3(mu-O)(mu(3)-O)] cores respectively. The comparative reactivity of alkyl and aryl acids towards TiCl4 is discussed.