The dialkoxo titanium complexes TiCp‘(η2-MBMP)Cl [Cp‘ = η5-C5H5 (1); η5-C5Me5 (2)] have been prepared in good yields by reaction of Li2(MBMP) with the corresponding monocyclopentadienyltrichloro titanium derivative. In a similar reaction the addition of 1 equiv of Li2(MBMP) to Ti(η5-C5H4SiMe2Cl)Cl3 generates the analogous titanium compound Ti(η5-C5H4SiMe2Cl)(η2-MBMP)Cl (3), while the ansa-cyclopentadienylalkoxo complex Ti(η5-C5H4SiMe2-η1-MBMP)Cl2 (4) is formed when MBMPH2 is treated with Ti(η5-C5H4SiMe2Cl)Cl3 in the presence of NEt3 in 1:1:2 molar ratio. Compounds 1, 2 and 4 have been characterized by single-crystal X-ray crystallography. DFT calculations were performed in order to elucidate the energies and geometries for these compounds. Upon addition of methylaluminoxane (MAO), the bisphenoxo complexes are active in the polymerization of α-olefins.

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The monocyclopentadienyl η 2-bisphenoxo chloro compound Ti(η 5-C5H4SiMe3)(η 2-MBMP)Cl (3), containing the bidentate dianionic η 2-MBMP ligand coordinated to the titanium center, has been prepared in good yield by reaction of 1 equiv of Li2(MBMP) with Ti(η 5-C5H4SiMe3)Cl3 in hexane, at −78 °C. The compound Ti(η 5-C5H4SiMe2Cl)(η 2-MBMP)Cl (1) reacts with alkylating reagents MgClR [R = Me, CH2Ph] or LiMe, in hexane or toluene, at low or room temperature, to afford the monocyclopentadienyl η 2-bisphenoxo derivatives Ti(η 5-C5H4SiMe2X)(η 2-MBMP)R [R = Me, X = Cl (4); R = X = Me (5); R = CH2Ph, X = Cl (6); R = X = CH2Ph (7)] or the ansa-monocyclopentadienylphenoxo dibenzyl complex Ti(η 5-C5H4SiMe2-η 1-MBMP)(CH2Ph)2 (8), depending on the reaction conditions. ansa-Monocyclopentadienylphenoxo dialkyl complexes Ti(η 5-C5H4SiMe2-η 1-MBMP)R2 [R = CH2Ph (8), Me (9)] can be alternatively synthesized by treatment of Ti(η 5-C5H4SiMe2-η 1-MBMP)Cl2 (2) with 2 equiv of MgCl(CH2Ph) or MgClMe. Compounds 3 and 8 have been characterized by single-crystal X-ray crystallography. Upon addition of methylaluminoxane, these bisphenoxo complexes are active in the polymerization of ethylene and styrene.

The mono(alkyl)bis(phenoxido)titanium complexes [TiRЈ(η 5 -C 5 R 5 )(η 2 -mbmp)] [R = H, RЈ = Me (4), CH 2 Ph (5), Ph (6), CH 2 SiMe 3 (7); R = Me, RЈ = Me (8), CH 2 Ph (9), CH 2 SiMe 3 (10); η 2 -mbmp = 2,2Ј-methylenebis(6-tert-butyl-4-methylphenoxido)] have been prepared in good yields by reaction of the appropriate alkylating reagent with the corresponding chlorido(cyclopentadienyl)bis(phenoxido)titanium derivative. Compound 6 reacts in toluene with traces of water to afford the µ-oxidotitanium complex {Ti(η 5 -C 5 H 5 )(η 2 -mbmp)} 2 (µ-O) (11). Compounds 8, 9 and 11 have been characterised by single-crystal X-ray crystallography, and density functional calculations have been performed in order to elucidate the energetic and structural properties of these compounds. The activity of these complexes in the presence of methylaluminoxane (MAO), B(C 6 F 5 ) 3 or [Ph 3 C][B(C 6 F 5 ) 4 ] as co-catalysts in the polymerisation of propylene and styrene has been studied. In an effort to model the nature of the catalytic species generated from these precursors, the reactions of the mono(cyclopentadienyl)bis(phenoxido)chlorido-and

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