Theoretical investigation of (MgCl2)xpolynuclear species formed during preparation of MgCl2-supported Ziegler–Natta catalysts from solid solvates

A novel approach for the study of the nature of the active species in Ziegler–Natta catalysis is described. This approach is based on the study of reliable structural models for disordered (MgCl2)xpolynuclear species which develop during the preparation of MgCl2-supported catalysts starting from MgCl2–Lewis-base adducts, and the calculation of X-ray diffraction patterns of these models. A method for the calculation of the X-ray powder diffraction patterns of the model structures is devised. This diffraction modelling method may be useful for the correct interpretation of the nature of some diffraction features in the X-ray diffraction patterns recorded during the structural evolution of MgCl2–Lewis-base adducts, which occurs in the preparation of the catalyst systems used for Ziegler–Natta polymerization of olefins.