Georgieva Ivelina, Trendafilova Natasha, Aquino Adélia J A, Lischka Hans
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Inorg Chem. 2007 Dec 10;46(25):10926-36. doi: 10.1021/ic7016616. Epub 2007 Nov 9.
The interaction of lanthanide(III) cations (Ln(III) = Sm(III), Eu(III), and Tb(III)) with the deprotonated form of the coumarin-3-carboxylic acid (cca-) has been investigated by density functional theory (DFT/B3LYP) and confirmed by reference MP2 and CCSD(T) computations. Solvent effects on the geometries and stabilities of the Ln(III) complexes were computed using a combination of water clusters and a continuum solvation model. The following two series of systems were considered: (i) Ln(cca)2+, Ln(cca)2+, Ln(cca)3 and (ii) Ln(cca)(H2O)2Cl2, Ln(cca)2(H2O)2Cl, Ln(cca)3. The strength and character of the Ln(III)-cca- bidentate bonding were characterized by calculated Ln-O bond lengths, binding energies, ligand deformation energies, energy partitioning analysis, sigma-donation contributions, and natural population analyses. The energy decomposition calculations predicted predominant electrostatic interaction terms to the Ln-cca bonding (ionic character) and showed variations of the orbital interaction term (covalent contributions) for the Ln-cca complexes studied. Electron distribution analysis suggested that the covalent contribution comes mainly from the interaction with the carboxylate moiety of cca-.
通过密度泛函理论（DFT/B3LYP）研究了镧系元素（III）阳离子（Ln(III) = Sm(III)、Eu(III) 和 Tb(III)）与香豆素 - 3 - 羧酸去质子化形式（cca-）的相互作用，并通过参考 MP2 和 CCSD(T) 计算进行了确认。使用水簇和连续介质溶剂化模型的组合计算了溶剂对 Ln(III) 配合物几何结构和稳定性的影响。考虑了以下两个系列的体系：（i）Ln(cca)2+、Ln(cca)2+、Ln(cca)3 和（ii）Ln(cca)(H2O)2Cl2、Ln(cca)2(H2O)2Cl、Ln(cca)3。通过计算 Ln - O 键长、结合能、配体变形能、能量划分分析、σ - 给体贡献和自然布居分析，对 Ln(III) - cca- 双齿键合的强度和性质进行了表征。能量分解计算预测 Ln - cca 键合主要是静电相互作用项（离子特征），并显示了所研究的 Ln - cca 配合物轨道相互作用项（共价贡献）的变化。电子分布分析表明，共价贡献主要来自与 cca- 的羧基部分的相互作用。
