REACTIONS OF TITANIUM TETRACHLORIDE WITH CARBOXYLIC-ACIDS - CRYSTAL AND MOLECULAR-STRUCTURE OF THE DINUCLEAR TITANIUM OXO COMPOUND [(TICL2(O(2)CBU(T))(BU(T)CO(2)H))O-2]

Reaction of TiCl4 (1 mol) with 2,2-dimethylpropanoic acid (2.5 mol) at room temperature yields the dinuclear oxo-bridged species [{TiCl2(O(2)CBu(t))(Bu(t)CO(2)H)}O-2] 1 which has been fully characterised by an X-ray crystal structure analysis. The two metal atoms are bridged by the oxo and two carboxylate groups, which with a co-ordinated acid molecule and two chlorine atoms on each titanium gives a slightly distorted octahedral environment around each metal centre. At 40 degrees C compound 1 decomposes to the trinuclear species [Ti3Cl3(O(2)CBu(t))(5)O-2], and at higher temperatures (100-120 degrees C) to another dinuclear ore derivative [{TiCl(O(2)CBu(t))(2)}O-2] which can also be obtained from the action of 2.2-dimethylpropanoic anhydride on TiCl4 in refluxing toluene. Acetic acid produces a similar, but less soluble, species to 1. Aromatic acids react differently; para-substituted aryl acids generally yield trinuclear compounds [Ti3Cl3(O(2)CC(6)H(4)X-p)(5)O-2] (X = Cl or Br) although the p-Bu(t) acid forms [{TiCl(O(2)CC(6)H(4)Bu(t)-p)(2)}O-2]. In contrast the ortho- and meta-substituted acids react to give either [Ti3Cl4(O(2)CR)(4)O-2] (R = C6H4Cl-o or -m) or [Ti4Cl5(O(2)CR)(7)O-2] (R = C(6)H(4)Me-o) derivatives