Organolanthanide and organoyttrium enolate chemistry. Synthesis of [(C5H4R)2Ln(.mu.-OCH:CH2)]2 complexes and the molecular structure of [(CH3C5H4)2Y(.mu.-OCH:CH2)]2
Organolanthanide and organoyttrium enolate chemistry. Synthesis of [(C5H4R)2Ln(.mu.-OCH:CH2)]2 complexes and the molecular structure of [(CH3C5H4)2Y(.mu.-OCH:CH2)]2
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DOI：
10.1021/om00138a002
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发表时间：
1986-07
期刊：
影响因子：
2.8
通讯作者：
W. Evans;Raul. Dominguez;T. Hanusa
中科院分区：
文献类型：
--
作者：
W. Evans;Raul. Dominguez;T. Hanusa
讨论正如导言中所讨论的，无论是简单的静电考虑，还是分子轨道计算，17或空间效应都不能预测茂金属(CBMeB)2Sm和(C6Me5)2Eu的弯曲结构。从所有这些观点来看，类似于在(CsMe5)2Fe中发现的平行环结构是可以预期的。46.(C_5Me_5)_2Sm和(C_5Me_6)_2Eu结构的相似性表明，不能用特定的4f®或4F7电子组态来解释弯曲结构。这些分子中的相对4f电子组态显然没有产生结构上可识别的影响。这一结果与以前的观察结果一致，即f电子构型对有机稀土络合物的结构影响很小。可以想象，(C6Me5)2Sm和(C5Me5)2Eu的弯曲结构是分子间相互作用和晶体堆积效应的结果。当然，晶体中存在着一些比正常短的分子间距离。Ln-C(11)‘距离是分子间金属碳接触中最短的，它最有可能是具有结构后果的相互作用的候选者。奇怪的是，如果存在这种相互作用，它发生在弯曲结构的一侧，而不是从更容易立体接触的前端。尚不清楚，为什么这样的“相互作用”不能发生在平行的环结构中，在这种结构中，不利的分子内甲基-甲基键将减少。此外，
Discussion As discussed in the Introduction, neither simple elec-trostatic considerations, nor molecular orbital calcula-tions, 17 nor steric effects predict the bent structure observed for metallocenes (CBMeB) 2Sm and (C6Me5) 2Eu. From all of these viewpoints, a parallel ring structure like that found in (CsMe5) 2Fe might be expected. 46 The sim-ilarity of the structures of (C5Me5) 2Sm and (C5Me6) 2Eu indicates that the bent structure cannot be explained on the basis of the specific 4f® or 4f7 electron configuration. The relative 4f electron configurations in these molecules evidently exert no structurally discernible effect. Such a result is consistent with previous observations that the f electron configuration has a minimal effect on the structure of organolanthanide complexes. 13It is conceivable that the bent structures of (C6Me5) 2Sm and (C5Me5) 2Eu result from intermolecular interactions and crystal packing effects. Certainly, some intermolecular distances exist in the crystal which are shorter than nor-mal. The Ln-C (ll)'distance, the shortest of the inter-molecular metal carbon contacts, would be the most likely candidate for an interaction with structural consequences. It is curious that this “interaction”, if it exists, occurs from the side of the bent structure rather than from the more sterically accessible front end. It is not clear, why such an “interaction” could not occur in a parallel ring structure in which unfavorable intramolecular methyl-methyl con-tacts would be diminished. In addition, the length of the