在芳族配体上具有包含脂族端基的取代基的二茂锆二茂合物与二当量的正丁基锂反应,通过脂族CH活化反应生成金属环茂锆茂配合物。具有末端脂族基团的ω-烯基取代的二氧化锆茂金属配合物以及具有纯脂族取代基的二氯化锆茂金属配合物也适用于此类金属环的合成。与甲基铝氧烷(MAO)结合使用时,这些金属环对于乙烯聚合而言是极好的催化剂。它们的活性可以是相应的二茂锆二氯化物离析物的活性的三倍半。催化剂25 / MAO能够生产2640 kg PE g -1 Zr h(60°C,戊烷溶液,10 bar乙烯压力)。
Substituted cyclopentadienylchromium(III) complexes containing neutral donor ligands. Synthesis, crystal structures and reactivity in ethylene polymerization
摘要:
Lithium derivatives of substituted cyclopentadiene ligands reacted with CrCl3(THF)(3) in THF solution to afford homodinuclear complexes of the type [{(eta(5)-RCp)CrCl(p-Cl)}2] [R = SiMe3 (1), CH2C(Me)CH2 (2)]. Complex 1 reacts with pyrazole (C3H4N2) to yield the mononuclear half-sandwich complex [(eta(5)-Me3SiCp)CrCl2(pyrazole)] (3). The similar complex [Cp*CrCl2(pyrazole)] (4) was synthesised by reaction of [{Cp*CrCl(mu-Cl)}2] with pyrazole. Complex 2 reacts with bidentate ligands to give binuclear complexes of the type [{(eta(5)-CH2C(Me)CH2Cp)CrCl2}(2)(mu-L-L)] [L-L = Ph2PCH2CH2PPh2 (5), trans-Ph2P(O)CH=CHP(O)Ph-2 (6)]. All complexes were structurally characterised by X-ray diffraction. After reaction with methylaluminoxane these complexes are active in the polymerization of ethylene. At 25 degreesC and 4 bar of ethylene, complex 3 yields polyethylene with a bimodal molecular weight distribution centred at 155,000 and 2000 g/mol. Complex 4 shows similar activity, yielding only the low molecular weight fraction. On the other hand, the binuclear complexes 5 and 6 under the same conditions were three times more active than mononuclear complexes. The melting point of the polymers indicates the formation of linear polyethylene. (C) 2003 Elsevier B.V. All rights reserved.