1 H and 13 C NMR Spectroscopic Study of Titanium(IV) Species Formed by Activation of Cp 2 TiCl 2 and [(Me 4 C 5 )SiMe 2 N t Bu]TiCl 2 with Methylaluminoxane (MAO)

Using 13 C and 1 H NMR spectroscopy, the products of the reaction of Cp 2 TiCl 2 with methylaluminoxane (MAO) at Al:Ti ratios of 5:1 to 300:1 have been identified as Cp 2 TiMeCl, Cp 2 TiMe 2, [Cp 2 TiMe(μ-Cl)Cp 2 TiCl] + [Me-MAO] - ( II 1 ), [Cp 2 TiMe(μ-Cl)Cp 2 TiMe] + [Me-MAO] - ( II 2 ), [Cp 2 TiMe(μ-Me)Cp 2 TiMe] + [Me-MAO] - ( II 3 ), the heterobinuclear ion pair [Cp 2 Ti(μ-Me) 2 AlMe 2 ] + [Me-MAO] - ( III ), and a “zwitterion-like” intermediate, formulated as Cp 2 TiMe + ←Me-Al - ⋮MAO ( IV ). In contrast, [(Me 4 C 5 )SiMe 2 N t Bu]TiCl 2 /MAO gives only zwitterion-like, not heterobinuclear, species.