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Synthesis and Crystal Structure of a μ-Methylene-μ-hydrido-dialanate [R2Al(μ-CH2)(μ-H)AlR2]? (R = CH(SiMe3)2) tert-Butyl lithium reacts with the recently synthesized methylene bridged dialuminium compound [(Me3Si)2CH]2Al? CH2? Al[CH(SiMe3)2]2 2 in the presence of TMEDA under β-elimination; the thereby formed hydride anion is bound in a chelating manner by both unsaturated aluminium atoms forming a 3c–2e–Al? H? Al bond. The crystal structure of the product shows two independent molecules differing only slightly in bond lengths and angles, but significantly in conformation. While one of the Al2CH heterocycles deviates little from planarity with a rough C2 symmetry for the whole anion, the other one is folded with an angle of 21.1° and the arrangement of the substituents is best described by Cs symmetry. 相似文献
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Guo‐Ming Wang Hai‐Lan Huang Hui Li Qing‐Hua Zheng 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(11):m531-m533
The two isomorphous lanthanide coordination polymers, {[Ln2(C6H4NO2)2(C8H4O4)(OH)2(H2O)]·H2O}n (Ln = Er and Tm), contain two crystallographically independent Ln ions which are both eight‐coordinated by O atoms, but with quite different coordination environments. In both crystal structures, adjacent Ln atoms are bridged by μ3‐OH groups and carboxylate groups of isonicotinate and benzene‐1,2‐dicarboxylate ligands, forming infinite chains in which the Er...Er and Tm...Tm distances are in the ranges 3.622 (3)–3.894 (4) and 3.599 (7)–3.873 (1) Å, respectively. Adjacent chains are further connected through hydrogen bonds and π–π interactions into a three‐dimensional supramolecular framework. 相似文献