SOLID-STATE NMR CHARACTERIZATION OF A SUPERACTIVE SUPPORTED ZIEGLER-NATTA CATALYST

The formation of CH-type catalysts has been investigated by high-resol ution and solid-state NMR. These catalysts are prepared from a soluble MgCl2 and 2-ethyl-1-hexanol adduct (MgCl2-3EH) by reaction with phtha lic anhydride (PA) to form dioctylphthalate (DOP) and then with TiCl4 in the presence of di-i-butylphthalate (BP). In the model systems MgCl 2.3EH/PA, MgCl2/BP, and MgCl2/TiCl4/BP, the ester is complexed with Mg Cl2 and/ or TiC4 in two or more states. Only single-ester C = 0 and OC H2 resonances are seen in TiCl4/BP, probably due to exchange of ester coordinations. CH-catalysts prepared by three different procedures exh ibit a single mode of bonding for the ester. The chemical shift values are consistent for ester complexed with MgCl2. The most active and st ereoselective catalyst has the most shielded chemical shift values for the C = 0 and -OCH2- carbons, shortest T1H and T1rho(H)H, and longest T(CH) relaxation times. These parameters change monotonically with th e decrease of activity and stereoselectivity of the catalyst preparati on.