Experimental Electron Density Studies for Investigating the Metal π-Ligand Bond: the Case of Bis(1,5-cyclooctadiene)nickel
Experimental Electron Density Studies for Investigating the Metal π-Ligand Bond: the Case of Bis(1,5-cyclooctadiene)nickel
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用于研究金属 π-配体键的实验电子密度研究：以双（1,5-环辛二烯）镍为例
DOI：
10.1021/ja972558l
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发表时间：
1998
影响因子：
15
通讯作者：
A. Sironi
中科院分区：
文献类型：
--
作者：
P. Macchi;D. Proserpio;A. Sironi
用x射线衍射（T = 125 K， 2θ≤96°反射17 051次）测定了晶体二（5-环二烯）镍Ni(COD)2的精确实验电子密度，并用分子中原子量子理论（QTAM）对其进行了解释。采用CCD面积检测器测量数据，并对其性能进行了测试。本文对π配体η - 2与金属原子配位的电子密度进行了实验研究，旨在测试杜瓦-查特-邓坎森（DCD）键合形式，为π配合物与金属环的二分法提供进一步的信息。QTAM分析显示，在NiC2三角形内，两个C（sp2）之间有一个键临界点，Ni与每个碳之间有两个键临界点，在其中心有一个环临界点。拓扑结构为凹环π配合物，整体成键图与DCD模型一致：Ni−C键路径中存在σ给能键和π反成键，在Ni−C键路径中存在σ给能键和π反成键。
The accurate experimental electron density of crystalline bis(5-cyclooctadiene)nickel, Ni(COD)2, has been determined by X-ray diffraction (T = 125 K, 17 051 reflections measured for 2θ ≤ 96°) and it has been interpreted in terms of quantum theory of atoms in molecules (QTAM). The data were measured with a CCD area detector, whose performances were tested. This experimental electron density study of a π-ligand η2-coordinated to a metal atom is intended to test the Dewar−Chatt−Duncanson (DCD) bonding formalism providing further information about the π-complex vs metallacycle dichotomy. QTAM analysis, within the NiC2 triangle, shows a ring structure with a bond critical point between the two C(sp2), two bond critical points between Ni and each carbon, and one ring critical point in its center. Topology speaks for a π-complex with a concave ring structure and the overall bonding picture is in agreement with the DCD model: σ-donation and π-back-bonding are recognized in the Ni−C bond paths, which are inwardly...