STUDIES ON COORDINATE BONDS IN POLYNUCLEAR COMPLEXES

多核配合物中配位键的研究

• 批准号: 05640638
• 负责人: SAKAI Yoichi
• 金额: $ 0.7万
• 依托单位: DAIDO INSTITUTE OF TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05640638/
• 关键词: Polynuclear Complex; Dinuclear Oxoanion; Oxo-bridge; Methy1-bridge; 5-Coordinate Carbon; bond angle; Angular Overlap Model; Linear Coordination Polymer; メチル架橋錯体; 配位構造; 配位結合; 二核錯体; 酸素架橋錯体; 七酸化二塩素; ピロ硫酸イオン; 二クロム酸イオン

The electroinic structure of bridging bonds in polynuclear complexes was cprrelated with their geometrical structure. The two following types of complexes were examined.1. The relationship between the electronic structure of the bridging bond and the bond angle at the bridging oxygen in R_2O_7^<n->-type dinuclear complexes was examined by using hybridized orbitals, localized molecular orbitals, linear combinations of the localized molecular orbitals, and delocalized molecular orbitals. In every case, the results of calculation showed a tendency that the bond angle increases with decreasing electronegativity of the central (R) atom, in agreement with the observed tendency. The bond angles obtained from calculations with reasonable parameter values were slightly smaller than the experimental bond angles. This deviation was taken as a token of partial ionic character of the bonds. Among the types of orbitals used in the calculation, the localized ones should be preferred at an elementary … More stage ; with simple delocalized molecular obirtals (without cinfigulation interactions), the bond energy only slightly depended on the bond angle.2. The peculiar structure of five-coordinate carbon atom observed in the methy1 bridge of linear polymers, [Be(CH_3)_2]_*, [Mg(CH_3)_2]_*, and [LiAl(C_2H_5)_4]_*, was investtigated. Because of unlikeliness of five covalency of carbon, an ionic model with metal ions and CH_3^-(C_2H_5^-)ligands was first examined. In every complex, electrostatic interaction between ions including long-range interactions stabilized the polymer. However, the calculated bond angle of the CH_3-bridge was much greater than the observed. On the other hand, an angular overlap treatment of convalent bond energies (relative values) gave too small bond angles in the Be and Mg complexes, where a molecuar orbital treatment allowing for ionic contribution gave reasonable bond angles. In the Li-Al complex, a model where the C-Al covalent bond is much stronger than the C-Li one, i.e.a model approximated by Li^+[Al(CH_3)_4]_-, gave a bond angle consistent with the observed angle. Less

多核配合物中桥键的电离子结构与其几何结构有关。对以下两种类型的复合物进行了检查。用<n->杂化轨道、定域分子轨道、定域分子轨道线性组合和离域分子轨道研究了R_2O_7^ -型双核配合物中桥键的电子结构与桥氧键角的关系。计算结果表明，在每种情况下，键角都随中心（R）原子电负性的减小而增大，这与观察到的趋势一致。计算得到的键角与合理的参数值略小于实验键角。这种偏离被认为是键的部分离子特征的表征。在计算中使用的轨道类型中，定域轨道应在初等轨道上优先使用。 ...更多信息 阶段;对于简单的离域分子轨道（没有束缚相互作用），键能仅轻微地依赖于键角。本文研究了线型聚合物[Be（CH_3）_2]_*、[Mg（CH_3）_2]_* 和[LiAl（C_2H_5）_4]_* 甲基桥中五配位碳原子的特殊结构。由于碳原子的五个共价键的不相似性，首次考察了金属离子与CH_3^-（C_2H_5^-）配体的离子模型。在每个复合物中，离子之间的静电相互作用（包括长程相互作用）使聚合物稳定。然而，计算的CH_3-桥键角远大于实测值。另一方面，角重叠处理的共价键能（相对值）得到太小的键角在Be和Mg配合物，其中的分子轨道处理允许离子的贡献给出合理的键角。在Li-Al络合物中，C-Al共价键比C-Li共价键强得多的模型，即Li^+[Al（CH_3）_4]_-模型，给出的键角与实验结果一致。少