[η3‐methallyl‐nickel‐dad]PF6 complex: new catalyst precursor for ethylene polymerization
[η3‐methallyl‐nickel‐dad]PF6 complex: new catalyst precursor for ethylene polymerization
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[η3-甲代烯丙基-镍-dad]PF6配合物：新型乙烯聚合催化剂前体
DOI：
10.1002/marc.1997.030180907
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发表时间：
1997
影响因子：
4.6
通讯作者：
Alessandro Cavagnolli
中科院分区：
文献类型：
--
作者：
R. F. Souza;R. S. Mauler;L. Simon;Fernanda Nunes;Daniela V. S. Vescia;Alessandro Cavagnolli
[q3-methallyl-nickel-dad] PF6是一种新型的乙烯聚合催化剂前体。该体系在常见的有机铝化合物如氯化二乙基铝存在下，在低的AUNi比和温和的反应条件下（温度在-10 °C和25 ° C之间，乙烯分压从1至15个大气压）是活性的。聚合物显示出广泛的甲基支化，其含量由反应参数如温度和乙烯压力控制。大量的学术和技术努力致力于合成具有受控的支链的高分子量聚乙烯。金属茂催化剂的出现已被认为是对该领域的主要贡献4 "。最近，Brookhart等人（536）已经表明，含有大体积二亚胺配体dad（ArN = C（R）C（R）= NAr，其中Ar = 2，6C6H3（i-Pr）2和R = H或Me）的阳离子Pd（I1）和Ni（I1）配合物在乙烯聚合中具有显著的活性。用这些催化剂生产的聚乙烯范围从高度线性到适度支化。这些发现被认为是均相催化聚合这一新兴领域的基石。尽管取得了这样的成功，但主要的缺点是络合物的复杂性，此外，需要大量过量的昂贵的甲基铝氧烷（MAO）助催化剂。在这项工作中，我们描述了[q3-methallyl-nickel-dad] PF6（1）与常见的有机铝化合物如二乙基氯化铝（DEAC）在低Al/Ni比下组合在温和的反应条件下（温度在-10 °C和25 "C之间，乙烯分压从1到15 atm）在乙烯聚合中是活性的。
SUMMARY The complex [q3-methallyl-nickel-dad]PF6 is a new catalyst precursor for ethylene polymerization. The system is active in the presence of usual organoaluminium compounds like diethylaluminium chloride, at low AUNi ratios and under mild reaction conditions (temperatures between -10°C and 25"C, ethylene partial pressure from 1 to 15 atm). The polymers show extensive methyl branching, whose content is controlled by reaction parameters like temperature and ethylene pressure. Large academic and technologic efforts have been devoted to the synthesis of high molecular weight polyethylene with controlled bran~hingl-~). The advent of metallocene catalysts has been recognized as a major contribution to this field4'. Recently Brookhart et al.536) have shown that cationic Pd(I1) and Ni(I1) complexes containing the bulky diimine ligands dad (ArN=C(R)C(R)=NAr, where Ar = 2,6C6H3(i-Pr)2 and R = H or Me) are remarkably active in ethylene polymerization. Polyethylenes produced with these catalysts range from highly linear to moderately branched. These findings have been considered as keystones in the emerging field of polymerization by homogeneous catalysis. In spite of such success, major drawbacks are the sophistication of the complexes and, moreover, the need of large excess of expensive methylaluminoxane (MAO) co-catalysts. In this work we describe that [q3-methallyl-nickel-dad]PF6 (1) combined with usual organoaluminium compounds like diethylaluminium chloride (DEAC) at low AI/Ni ratios is active in ethylene polymerization under mild reaction conditions (temperatures between -10°C and 25"C, ethylene partial pressure from 1 to 15 atm).