An yttrium-based system to evaluate Lewis base coordination to an electropositive metal in a metallocene environment
An yttrium-based system to evaluate Lewis base coordination to an electropositive metal in a metallocene environment
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DOI：
10.1021/om010908d
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发表时间：
2002-04-29
期刊：
影响因子：
2.8
通讯作者：
Ziller, JW
中科院分区：
文献类型：
--
作者：
Evans, WJ;Fujimoto, CH;Ziller, JW
非溶剂化的钇络合物（C5 Me 5）（2）Y（mu-Cl）Y（C5 Me 5）（2）Cl（1）提供了一个方便的平台，在此平台上比较氧供体配体和单体与刘易斯酸性金属离子的配位化学。I与2当量的含氧底物反应形成单体络合物（C_5Me_5）（2）YCl（L）（L = THF（2），二苯甲酮（3），甲基丙烯酸甲酯（4），ε-己内酯（5），六甲基磷酰胺（6），己内酰胺（7），1-甲基-2-吡咯烷酮（8），N，N '-二甲基亚丙基脲（9））。每一种都很容易结晶，这允许比较固态下的Y-O相互作用。X-射线数据表明，Y-O键长的大小顺序为THF >二苯甲酮>甲基丙烯酸甲酯> ε-己内酯>六甲基磷酰胺> ε-己内酰胺> 1-甲基-2-吡咯烷酮> NW-二甲基亚丙基脲，尽管这些键长的范围很小，有些键长在实验误差范围内是相同的。在ε-己内酰胺的情况下，双加合物（C5 Me 5）（2）YCl（ε-己内酰胺）（2）（10）可以从I和过量ε-己内酰胺的反应中分离出来。1H-1 NMR光谱表明，在溶液中与2-9的（C5 Me 5）（2）YCl（L）/L'配体置换反应遵循与键长一致的趋势，除了（C5 Me 5）（2）YCl（ε-己内酰胺）（7），其中L参与与氯化物的氢键合。
The unsolvated bimetallic yttrium complex (C5Me5)(2)Y(mu-Cl)Y(C5Me5)(2)Cl (1) provides a convenient platform upon which to compare the coordination chemistry of oxygen-donor ligands and monomers with Lewis acidic metal ions. Reaction of I with 2 equiv of oxygen-containing substrates formed the monomeric complexes (C5Me5)(2)YCl(L) (L = THF (2), benzophenone (3), methyl methacrylate (4), epsilon-caprolactone (5), hexamethylphosphoramide (6), c-caprolactam (7), 1-methyl-2-pyrrolidinone (8), N,N'-dimethylpropyleneurea (9)). Each of these readily crystallize, which allows comparison of the Y-O interaction in the solid state. The X-ray data show that the numerical values of the measured Y-O lengths decrease in the order THF > benzophenone > methyl methacrylate > epsilon-caprolactone > hexamethyl-phosphoramide > E-caprolactam > 1-methyl-2-pyrrolidinone > NW-dimethylpropyleneurea, although these bond lengths span only a short range and some are the same within experimental error. In the case of epsilon-caprolactam, a bis adduct, (C5Me5)(2)YCl(epsilon-caprolactam)(2) (10), can be isolated from the reaction of I and excess E-caprolactam. H-1 NMR spectroscopy indicates that (C5Me5)(2)YCl(L)/L' ligand displacement reactions in solution with 2-9 follow a trend consistent with the bond lengths except for (C5Me5)(2)YCl(epsilon-caprolactam) (7), in which L participates in hydrogen bonding to the chloride.