DIASTEREOSELECTIVE SYNTHESIS, MOLECULAR-STRUCTURE, AND SOLUTION DYNAMICS OF HYLENEBIS(4,7-DIMETHYL-ETA(5)-1-INDENYL])ZIRCONIUM AND HYLENEBIS(4,7-DIMETHYL-ETA(5)-1-INDENYL])ZIRCONIUM DICHLORIDE ISOMERS AND CHAIN TRANSFER-REACTIONS IN PROPENE POLYMERIZATION WITH THE RAC ISOMER
L. Resconi et al., DIASTEREOSELECTIVE SYNTHESIS, MOLECULAR-STRUCTURE, AND SOLUTION DYNAMICS OF HYLENEBIS(4,7-DIMETHYL-ETA(5)-1-INDENYL])ZIRCONIUM AND HYLENEBIS(4,7-DIMETHYL-ETA(5)-1-INDENYL])ZIRCONIUM DICHLORIDE ISOMERS AND CHAIN TRANSFER-REACTIONS IN PROPENE POLYMERIZATION WITH THE RAC ISOMER, Organometallics, 15(23), 1996, pp. 5046-5059
The known hylenebis(4,7-dimethyl-eta(5)-1-indenyl)]ZrCl2(2r) and its m
eso isomer (2m) have been compared with the prototypal chiral isospeci
fic rac-[ethylenebis(eta(5)-1-indenyl)]ZrCl2 (1r) and its aspecific me
so isomer Im in terms of molecular structures, solution dynamics, and
ligand substitution effect on polymerization performance. in Liquid pr
opene at 50 degrees C, 2r/MAO produces iPP with appreciably higher iso
tacticity but lower molecular weight and regiospecificity than 1r/MAO.
The lower molecular weight obtained with 2r in liquid monomer is due
to predominant chain transfer to the monomer after a secondary propene
insertion, producing >90% cis-2-butenyl- end groups. At lower propene
concentration, 2r/MAO allows both beta-hydrogen transfer after a prim
ary insertion and beta-methyl transfer, The low-activity 2m/MAO cataly
st produces low molecular weight aPP. The diastereoselective synthesis
of 2r,m via the corresponding rac- and 4,7-dimethy-1-(trimethylsilyl)
-3-indenyl)ethane,is reported. The crystal and molecular structures of
(4,7-dimethyl-1-(trimethylsilyl)-3-indenyl)ethane, 2r,m, have been de
termined.