A series of yttrium, ytterbium, and lanthanum hexa-or heptacoordinate complexes were prepared and their catalytic activities tested in the hetero Diels–Alder reaction between crotonaldehyde and ethyl vinyl ether. It was found that a pKa below 7 of the ligand was necessary but not sufficient for catalytic activity. It was determined that the ligand should possess a perfluoromethyl-β-diketonate functionality. Other factors such as bite angle and hinging motion may also play a determining role. Keywords: lanthanide, catalyst, hetero Dielsis–Alder, yttrium, ytterbium, lanthanum.
一系列的
钇、
镱和
镧的六或七配位配合物已被制备并在
丁烯醛和乙基
乙烯醚的杂Diels-Alder反应中测试了它们的催化活性。发现
配体的pK
a低于7是必要的但不足以保证催化活性。确定了
配体应具有
全氟甲基-
β-二酮酸酯功能。其他因素,如咬合角度和铰链运动,也可能发挥决定性作用。关键词:
镧系元素、催化剂、杂Diels-Alder、
钇、
镱、
镧。