MgCl2-supported Ziegler-Natta catalysts: synthesis and X-ray diffraction characterization of some MgCl2-Lewis Bases adducts

Some adducts of MgCl2 and Lewis bases (or donors) B were examined, having a composition MgCl2 • 2B, where B = Ethyl (Et) formate, Et acetate, Et propionate, Et benzoate, Et crotonate, acetone, 2-butanone and EtOH. The crystallographic investigation of these adducts, carried out on polycrystalline powders and some single crystals, shows some remarkable structural analogies for all examined donors. In particular, the X-ray diffraction patterns of the adducts indicate the total absence of the close-packing of chlorine which characterizes α-MgCl2 and the presence of covalent Cl-Mg-Cl chains. The obtained data are correlated with the preparation of active supports for Ziegler-Natta olefin polymerization: after total elimination of B, a disordered structure of MgCl2 is obtained, which is coincident with the reported one for the mechanically activated (by ball-milling) MgCl2 and previously described both in the scientific and in the patent literature.