The influence of the ligands on the formation and stability of µ-oxo-bridged Ti(IV) complexes has been studied. Reaction of LTiCl3 (1) and LAlMe(OLi) (L = HC(CMeN(2,6-iPr2C6H3))2, “NacNac”) afforded intermediate LTiCl2(µ-O)AlMeL (5) in solution, which was converted to LTiCl(µ-O)2TiClL (6) and LAlMeCl within 2 days. The decomposition of 5 was estimated to be thermodynamically favorable. The interaction of LTiMe3 (3) and LAlMe(OH) yielded the intermediate LTiMe2(µ-O)AlMeL (7). Complex 7 decomposes in solution giving the titanium oxo complex LTiMe(O) (8) and LAlMe2. The calculated ΔG298 for this reaction is −128 kJ mol−1. The degradation of LTiMe2(µ-O)AlMeL is slow and follows first order kinetics with k2 = 4.09(7) × 10−7 s−1. The dimeric complex LTiMe(µ-O)2TiMeL–toluene (9a) was isolated from the reaction of 3 with LAlMe(OH) in toluene and LTiMe(µ-O)2TiMeL–hexane (9b) from hexane. The dimerization of 8 yielding LTiMe(µ-O)2TiMeL (9) is marginally endothermic, with a calculated ΔG298 of +27 kJ mol−1. The formation of the solid 9 is due to the lattice stabilization. The solid µ-oxo-bridged complex 9 and Mes3Ga were obtained from the reaction of LTiMe3 with [Mes2Ga(OH)]2–THF in toluene, and 9 was also isolated from the reaction of LTiMe3 with 1 equiv. of H2O in toluene. Compounds LTiCl3 (1), LTiCl(µ-O)2TiClL (6), 9a and 9b have been characterized by X-ray single crystal structure, NMR, IR, EI-MS and elemental analysis. Complexes 5, 7 and 8 have been characterized by NMR. Compounds 3, 6 and 9 possess moderate catalytic activity in the polymerization of ethylene.
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