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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Formation and structure of Co_2O_4: A combined IR matrix isolation and theoretical study
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Formation and structure of Co_2O_4: A combined IR matrix isolation and theoretical study

机译：Co_2O_4的形成与结构：红外矩阵分离与理论研究相结合

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The formation and structure of dicobalt tetroxide (Co_2O _4) has been investigated using matrix isolation in solid neon and argon coupled to infrared spectroscopy and quantum chemical methods. It is found that Co_2O_4 can be formed by dimerization of cobalt dioxide without activation energy by diffusion of ground state CoO_2 molecules at 9 K in the dark. The IR data on eight fundamentals, isotopic effects and quantum chemical calculations are both consistent with a centro-symmetrical structure with two pairs of equivalent oxygen atoms, engaged in a stronger terminal Co-O bond and in a weaker bridging Co-O-Co position. Evidence for other, metastable states is also presented, but the data are not conclusive. The electronic structure and formation pathway has been investigated using the Tao-Perdew-Staroverov-Scuseria/triple-zeta valence polarived basis set (TPSS/TZVP) and broken symmetry unrestricted density functional theory (BS-UDFT) approach and the ground electronic state is predicted to be an open shell ~1A_g singlet with the quintet, triplet, septet, and nonet states above by 3.3, 4.9, 9.3, and 27.7 kcal/mol, respectively, but certainly has a complex multireference character that hinders the use of more precise multireference approaches. Different formation pathways have been considered, and the 2(O=Co=O) → Co_2O_4 dimerization reaction is found to be the only barrierless channel and to be strongly exothermic. Comparisons with another transition metal (TM) oxide system (V _2O_4) suggests that the difference in predicted ground state geometries in TM_2O_4 systems might be due in HOMO-LUMO shapes of the isolated dioxide subunits and optimal overlap configurations.
机译：使用固体氖气和氩气中的基质分离，红外光谱和量子化学方法研究了四氧化二钴（Co_2O _4）的形成和结构。发现在黑暗中9 K时基态CoO_2分子的扩散可以通过二氧化钴的二聚而形成无活化能的Co_2O_4。八个基本原理，同位素效应和量子化学计算的红外数据都与具有两对等效氧原子的中心对称结构一致，它们参与更强的末端Co-O键和较弱的Co-O-Co桥联位置。还提供了其他亚稳态的证据，但数据不是结论性的。电子结构和形成途径已使用Tao-Perdew-Staroverov-Scuseria /三重zeta价极化基集（TPSS / TZVP）和破对称非限制密度泛函理论（BS-UDFT）方法进行了研究，基态电子态为预计将是一个开放的壳〜1A_g单重态，其五重态，三重态，septet和nonet状态分别高于3.3、4.9、9.3和27.7 kcal / mol，但肯定具有复杂的多引用特征，这妨碍了更精确的使用。多参考方法。已经考虑了不同的形成途径，并且发现2（O ＝ Co ＝ O）→Co_2O_4二聚反应是唯一的无障碍通道并且强烈放热。与另一种过渡金属（TM）氧化物系统（V _2O_4）的比较表明，TM_2O_4系统中预测的基态几何形状的差异可能归因于孤立的二氧化亚基的HOMO-LUMO形状和最佳重叠构型。

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