Monocyclopentadienyl Chloro Bisphenoxo Ti(η⁵-C₅H₄SiMe₂Cl)(η²-MBMP)Cl Derivative:  Ti−Cl, Ti−O, and Si−Cl Reactivity. Crystal Structure of Ti(η⁵-C₅H₄SiMe₃)(η²-MBMP)Cl and Ti(η⁵-C₅H₄SiMe₂-η¹-MBMP)(CH₂Ph)₂

Abstract

The monocyclopentadienyl η2-bisphenoxo chloro compound Ti(η5-C5H4SiMe3)(η2-MBMP)Cl (3), containing the bidentate dianionic η2-MBMP ligand coordinated to the titanium center, has been prepared in good yield by reaction of 1 equiv of Li2(MBMP) with Ti(η5-C5H4SiMe3)Cl3 in hexane, at −78 °C. The compound Ti(η5-C5H4SiMe2Cl)(η2-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 η2-bisphenoxo derivatives Ti(η5-C5H4SiMe2X)(η2-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(η5-C5H4SiMe2-η1-MBMP)(CH2Ph)2 (8), depending on the reaction conditions. ansa-Monocyclopentadienylphenoxo dialkyl complexes Ti(η5-C5H4SiMe2-η1-MBMP)R2 [R = CH2Ph (8), Me (9)] can be alternatively synthesized by treatment of Ti(η5-C5H4SiMe2-η1-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.