Cerium oxidation state and covalent 4f-orbital contributions in the ground state of bis(η8-pentalene)cerium
Cerium oxidation state and covalent 4f-orbital contributions in the ground state of bis(η8-pentalene)cerium
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DOI：
10.1016/j.jorganchem.2015.05.063
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发表时间：
2015-10-01
影响因子：
2.3
通讯作者：
Moossen, Oliver
中科院分区：
文献类型：
--
作者：
Dolg, Michael;Moossen, Oliver
用相对论量子化学从头算方法研究了夹心配合物双（η（8）-并环戊二烯）铈Ce（C8 H6）（2），分析了Ce 4f与配体π轨道相互作用的性质.它示出了一个多构型的基态波函数的完整的活性空间品种，通过在强相互作用轨道的空间中的轨道旋转的装置，它是可能的，以产生几乎纯的Ce 4f和配体π轨道，而不改变总能量。这些轨道每个被一个电子占据，导致开壳层4f（1）pi（1）基态构型。能量更高的闭合壳层4f（0）pi（2）构型的混合物导致单重基态，使该络合物成为基于Ce（III）的晶格近藤系统的分子类似物的另一个例子。进一步的分析表明，Ce 4f-配体π相互作用对应于一个显著拉伸的共价键：轨道和构型混合系数以及局部自旋和占据数波动与氢二聚体H-2在原子间距离约为平衡距离的两倍时非常相似。(C)2015 Elsevier B. V.版权所有。
The sandwich complex bis(eta(8)-pentalene)cerium Ce(C8H6)(2) was investigated by relativistic quantum chemical ab initio methods and the nature of the interaction between the Ce 4f and ligand pi orbitals was analyzed. It is shown for a multi-configurational ground state wavefunction of the complete active space variety that by means of an orbital rotation in the space of the strongly interacting orbitals it is possible to generate nearly pure Ce 4f and ligand pi orbitals without changing the total energy. These orbitals are occupied by one electron each, leading to an open-shell 4f(1) pi(1) ground state configuration. The admixture of the energetically higher closed-shell 4f(0) pi(2) configuration leads to a singlet ground state, making the complex another example for a molecular analog of a Ce(III)-based lattice Kondo system. A further analysis using local spin and occupation number fluctuations in a two-electron two-orbital description reveals that the Ce 4f-ligand pi interaction corresponds to a significantly stretched covalent bond: orbital and configuration mixing coefficients as well as local spin and occupation number fluctuations are very similar to those of hydrogen dimer H-2 at an interatomic distance of about two times the equilibrium distance. (C) 2015 Elsevier B.V. All rights reserved.