Solid-State NMR characterization of a superactive supported ziegler–natta catalyst

The formation of CH-type catalysts has been investigated by high-resolution and solid-state NMR. These catalysts are prepared from a soluble MgCl₂ and 2-ethyl-1-hexanol adduct (MgCl₂·3EH) by reaction with phthalic anhydride (PA) to form dioctylphthalate (DOP) and then with TiCl₄ in the presence of di-i-butylphthalate (BP). In the model systems MgCl₂·3EH/PA, MgCl₂/BP, and MgCl₂/TiCl₄/BP, the ester is complexed with MgCl₂ and /or TiCl₄ in two or more states. Only single-ester C?O and OCH₂ resonances are seen in TiCl₄/BP, probably due to exchange of ester coordinations. CH-catalysts prepared by three different procedures exhibit a single mode of bonding for the ester. The chemical shift values are consistent for ester complexed with MgCl₂. The most active and stereoselective catalyst has the most shielded chemical shift values for the C?O and —OCH₂— carbons, shortest T^H₁ and T^H_1p, and longest T_CH relaxation times. These parameters change monotonically with the decrease of activity and stereoselectivity of the catalyst preparation. © 1993 John Wiley & Sons, Inc.