in toluene (inert atmosphere); slow addn. of AlEtCl2 in toluene at -78°C toa soln. of Ti complex in toluene, stirring (low temp., 2 h); quenching (pyridine), warming to room temp., removal of volatiles (vac.), washing (hexane), mixing the residual gum with toluene, isoln. of theproduct from hexane and toluene solns.; yield almost quantitative;