Homopolymerizations and random copolymerizations of olefins with amino‐substituted cyclopentadienylchromium complexes

Abstract

1-(2-N,N-Dimethylaminoethyl)-2,3,4,5-tetramethylcyclopentadienyl-chromium dichloride (1), (2-N,N-dimethylaminoethyl)cyclopentadienylchromium dichloride (6), and (2-N,N-dimethylaminoethyl)indenylchromium dichloride (7) in the presence of modified methylaluminoxane exhibit high catalytic activities for the polymerization of ethylene with random copolymerizations of ethylene with propylene, ethylene with 1-hexene, and propylene with 1-hexene. These initiators conduct polymerizations to give high molecular weight polymers with low polydispersities. However, the stereoregularities are very poor in these reactions.

Unique catalytic behavior of chromium complexes having halogenated bis(imino)pyridine ligands for ethylene polymerization

“…Very recently, Esteruelas et al19 and Small et al20 have reported that bis(imino)pyridine complexes of chromium were as active as Group 4 metallocenes. We have also been studying polymerization catalysis of bis(imino)pyridinechromium complexes as well as Cp‐amino,21 disiloxanediamido,22 and binaphtholato complexes 23. In this article, we report synthesis of a series of bis(imino)pyridine chromium(III) trichloride complexes and their catalytic behavior for ethylene polymerization.…”

Half-sandwich chromium(iii) complexes bearing β-ketoiminato and β-diketiminate ligands as catalysts for ethylene polymerization

“…Cooling to -30 • C to give blue-green or green solid or crystals. Crystal data for complex 1c: C 22 H 29 ClCrNO, M = 410.91, triclinic, space group P 1, a = 8.976(6), b = 9.965(6), c = 12.294(8) A ˚, a = 83.284(9) • , b = 81.187(9) • , g = 81.543 (10) • , V = 1069.8(12) A ˚3, D c = 1.276 g cm -3 (Z = 2), R 1 = 0.0551 (I > 2s(I)) and wR 2 = 0.1513 (all data), reflections collected/unique = 4472/3714, R int = 0.0749. For complex 2: C 22 H 22 ClCrN 2 , M = 401.87, monoclinic, space group P2 1 /c, a = 14.033( 5), b = 23.567(8), c = 12.120(4) A ˚, b = 90.023(5) • , V = 4008(2) A ˚3, D c = 1.332 g cm -3 (Z = 8), R 1 = 0.0454 (I > 2s(I)) and wR 2 = 0.1041 (all data), reflections collected/unique = 16489/3525, R int = 0.0666.…”

Synthesis and Characterization of Constrained Geometry Oxygen and Sulphur Functionalized Cyclopentadienylchromium Complexes and Their Use in Catalysis for Olefin Polymerization

“…It is mainly because the chemistry of Cr(III) is particularly difficult to study as a result of its paramagnetic nature. In recent years, some of the most significant advances in Cp-based chromium catalyst systems have been made using precatalysts that bear an additional neutral donor and bridged the Cp unit [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ], so-called CGC system (CGC = Constrained Geometry Catalyst). They have already been used as efficient catalyst precursors for ethylene or 1-hexene homo (co)-polymerization, which are listed in Figure 1 .…”