SYNTHESIS AND CHARACTERIZATION OF NEW DIMERIC AND TETRAMERIC VANADIUMINTERMEDIATES OF OLEFIN POLYMERIZATION CATALYSTS - CRYSTAL-STRUCTURESOF [V-2(MU-CL)(2)CL-4(MECO(2)ET)(4)] AND (VOCL2[CH2(CO(2)ET)(2)])(4)]CENTER-DOT-2CH(2)CL(2)

The direct reaction of VCl3 and ethyl acetate yields [V-2(mu-Cl)(2)Cl- 4(MeCO(2)Et)(4)] 1. The compound [V-2(mu-Cl)(2)Cl-4{CH2(CO(2)Et)(2)}(2 )] 2 was obtained in dichloromethane via the substitution of MeCO(2)Et in 1 by ethyl malonate. During crystallization of 2, under the influe nce of dioxygen and moisture, the tetrameric compound [{VOCl2[CH2(CO(2 )Et)(2)]}(4)]. 2CH(2)Cl(2) 3 was formed. The crystal structures of 1 a nd 3 have been determined by single-crystal X-ray diffraction studies . The dimeric compound 1 exhibits six-co-ordinate V-III centres [separ ated by a V ... V distance of 3.590(1) Angstrom] surrounded by two ter minal Cl atoms, two carbonyl oxygen atoms of co-ordinated ethyl acetat e molecules and linked by two bridging Cl atoms. In the tetrameric spe cies 3, the four vanadium(IV) atoms have equivalent octahedral geometr ies. being bonded by two mutually cis chlorine atoms, two mutually cis carbonyl oxygen atoms of chelate ethyl malonate and two mutually cis oxygen atoms. High catalytic activity was found for 1, 2 and [V-2(mu-C l)(2)Cl-4(thf)(4)] (thf = tetrahydrofuran).