KINETICS OF SUBSTITUTION AT TERNARY TITANIUM(IV) CYCLOPENTADIENYL, PYRONATO OR PYRIDINATO HALIDE OR ALKOXIDE COMPLEXES

Rate laws and kinetic parameters are reported for substitution at tita nium(IV) complexes Ti(LL)2X2, where LLH = cyclopentadiene, the 4-pyron e ethylmaltol, several 4-pyridinones, and related ligands, and X = hal ide or alkoxide, in acetonitrile solution at 298.2 K. Reactivities are discussed in terms of the nature of the leaving group, the entering g roup and the non-leaving ligand LL-. Activation volumes of -15 and -12 cm3 mol-1 have been determined for thiocyanate attack at Ti(cp)2Cl2 a nd Ti(etmalt)2Cl2 respectively. Substitution mechanisms are discussed in the light of the kinetic parameters obtained.