Ionization of TiCl4 and MgCl2 during the Formation of a High-Activity α-Olefin Polymerization Catalyst. Crystal Structures of [cis-{C2H4(CO2Et)2}2Cl2Ti][SbCl6]2·CH2Cl2 and [Mg{C2H4(CO2Et)2}3][MgCl4]·2CH2Cl2

Abstract

The cis-dichlorobis(diethyl succinate)titanium(IV) bis(hexachloroantimonate(V))−dichloromethane(1/1) salt, [cis-{C2H4(CO2Et)2}2Cl2Ti][SbCl6]2·CH2Cl2 (1), was prepared by direct reaction of TiCl4, diethyl succinate, and SbCl5 in CH2Cl2. catena-(μ-Diethyl succinate-O,O‘)bis(diethyl succinate-O,O‘)magnesium(II) tetrachloromagnesate(II)−dichloromethane(1/2), [Mg{C2H4(CO2Et)2}3][MgCl4]·2CH2Cl2 (2), was formed by substitution of ethyl acetate in [MgCl2(CH3CO2Et)] for diethyl succinate. Both species have been structurally characterized. Complex 1 crystallized in the space group Pnn2, with a = 16.178(5), b = 12.784(4), and c = 10.427(2) Å. Compound 2 belongs to the C2/c space group with a = 26.121(6), b = 10.086(2), c = 17.947(4) Å and β = 116.76(3)°. In the [cis-{C2H4(CO2Et)2}2Cl2Ti]2+ cation, the titanium atom is octahedrally coordinated by two mutually cis chlorine atoms and four carbonyl oxygen atoms of two chelating diethyl succinate molecules. The ([Mg{C2H4(CO2Et)2}3]2+)∞ cation in the crystalline state is a linear polymer formed by the [Mg{C2H4(CO2Et)2}2]2+ units linked by other diethyl succinate ligands. In this cation, each magnesium atom is octahedrally coordinated by six carbonyl oxygen atoms of ethyl succinate molecules. Catalytic activity was found for ethylene polymerization by 1.