Experimental and theoretical charge density study of chemical bonding in a Co dimer complex.
Experimental and theoretical charge density study of chemical bonding in a Co dimer complex.
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Co二聚体复合物中化学键合的实验和理论电荷密度研究。
DOI：
10.1021/ja076152c
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发表时间：
2008
影响因子：
15
通讯作者：
B. Iversen
中科院分区：
文献类型：
--
作者：
J. Overgaard;H. Clausen;J. Platts;B. Iversen
Co2（CO）6（HC[三键] CC 6 H10 OH）（1）在结晶状态下的电荷密度已经使用（i）在非常低的温度（15 K）下使用同步加速器源和（ii）在中间温度（100 K）下使用晶体的常规源收集的单晶X射线衍射数据的多极细化来确定。通过完整的活性空间和密度泛函理论计算增强了X射线电荷密度模型。不同的电荷分布的拓扑分析表明，这两个钴原子是不成键的原子在分子中的量子理论（QTAIM）意义上的词。然而，源函数和总能量密度的行为表明，在Co-Co相互作用中存在一些键的性质。桥连炔片段提供了一种不寻常的键合情况，两个Co-C键临界点和“CoC 2”环临界点之间的电子密度差异极小。因此，该结构接近拓扑突变点。从两个衍射数据集和从头算理论得到的结果的比较表明，在这个特殊的原子环境中的实验电子密度的拓扑结构是高度敏感的测量误差和潜在的缺陷的多极模型的微妙影响，或晶体场的影响。因此，即使在不对称单元中的两个相同的分子也显示出改变的键合模式。
The charge density of Co2(CO)6(HC[triple bond]CC6H10OH) (1) in the crystalline state has been determined using multipolar refinement of single-crystal X-ray diffraction data collected (i) with a synchrotron source at very low temperatures (15 K) and (ii) using a conventional source with the crystal at intermediate temperature (100 K). The X-ray charge density model is augmented by complete active space and density functional theory calculations. Topological analyses of the different charge distributions show that the two Co atoms are not bonded to each other in the quantum theory of atoms in molecules (QTAIM) sense of the word. However, the behavior of the source function and the total energy density indicate that there is some bond-like character in the Co-Co interaction. The bridging alkyne fragment provides an unusual bonding situation, with extremely small electron density differences between the two Co-C bond critical points and the "CoC2" ring critical point. Thus, the structure is close to a topological catastrophe point. Comparison of the results obtained from the two diffraction data sets and ab initio theory suggests that the topology of the experimental electron density in this special atomic environment is highly sensitive to subtle effects of measurement errors and potential shortcomings of the multipole model, or to effects of the crystal field. Thus, even the two identical molecules in the asymmetric unit show altered bonding patterns.