Departamento de Física, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires , Ciudad Universitaria 1428 , Buenos Aires , Argentina.
Instituto de Física de Buenos Aires , Consejo Nacional de Investigaciones Científicas y Técnicas , Ciudad Universitaria 1428 , Buenos Aires , Argentina.
Inorg Chem. 2018 Jul 2;57(13):7763-7769. doi: 10.1021/acs.inorgchem.8b00815. Epub 2018 Jun 12.
We analyze the magnetic properties of three mononuclear Co(II) coordination complexes using quantum chemical complete active space self-consistent field and N-electron valence perturbation theory approaches. The complexes are characterized by a distorted tetrahedral geometry in which the central ion is doubly chelated by the icosahedral ligands derived from 1,2-(HS)-1,2-CBH (complex I), from 1,2-(HS)-1,2-CBH and 9,12-(HS)-1,2-CBH (complex II), and from 9,12-(HS)-1,2-CBH (complex III), which are two positional isomers of dithiolated 1,2-dicarba- closo-dodecaborane (complex I). Complex I was realized experimentally recently (Tu, D.; Shao, D.; Yan, H.; Lu, C. Chem. Commun. 2016, 52, 14326) and served to validate the computational protocol employed in this work, while the remaining two proposed complexes can be considered positional isomers of I. Our calculations show that these complexes present different axial and rhombic zero-field splitting anisotropy parameters and different values of the most significant components of the g tensor. The predicted axial anisotropy D = -147.2 cm for complex II is twice that observed experimentally for complex I, D = -72.8 cm, suggesting that this complex may be of interest for practical applications. We also analyze the temperature dependence of the magnetic susceptibility and molar magnetization for these complexes when subject to an external magnetic field. Overall, our results suggest that o-carborane-incorporated Co(II) complexes are worthwhile candidates for experimental exploration as single-ion molecular magnets.
我们使用量子化学完全活性空间自洽场和 N 电子价层微扰理论方法分析了三个单核 Co(II) 配位配合物的磁性。这些配合物的特征是扭曲的四面体形几何结构，其中中心离子被来自 1,2-(HS)-1,2-CBH 的五角形配体（配合物 I）、来自 1,2-(HS)-1,2-CBH 和 9,12-(HS)-1,2-CBH 的双螯合（配合物 II）和来自 9,12-(HS)-1,2-CBH 的单螯合（配合物 III）所稳定，后者是二硫代 1,2-二碳杂 closo-十二硼烷（配合物 I）的两个位置异构体。配合物 I 最近在实验上得到了实现（Tu, D.; Shao, D.; Yan, H.; Lu, C. Chem. Commun. 2016, 52, 14326），并用于验证本工作中使用的计算方案，而其余两个提出的配合物可以被认为是 I 的位置异构体。我们的计算表明，这些配合物具有不同的轴向和菱形零场分裂各向异性参数以及 g 张量最重要分量的不同值。预测的配合物 II 的轴向各向异性参数 D = -147.2 cm-1 是实验观察到的配合物 I 的 D = -72.8 cm-1 的两倍，这表明该配合物可能对实际应用感兴趣。我们还分析了这些配合物在受到外磁场时的磁化率和摩尔磁化随温度的变化。总体而言，我们的结果表明，o-碳硼烷合 Co(II) 配合物是作为单离子分子磁体进行实验探索的有价值候选物。
