Kaneko Masashi, Nakashima Satoru
Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4, Shirakata, Tokai-mura, Ibaraki 319-1195, Japan.
Natural Science Center for Basic Research and Development, Hiroshima University, 1-4-2, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
Inorg Chem. 2021 Sep 6;60(17):12740-12752. doi: 10.1021/acs.inorgchem.1c00239. Epub 2021 Aug 19.
In the present study, density functional theory (DFT) calculation was applied to Vaska's complexes of formula -[IrX(CO)(PPh)] and their oxidative adducts with small molecules (YZ) including H, i.e., -[IrClYZ(CO)(PPh)], to successfully correlate the electronic states of the complexes with the corresponding Ir Mössbauer spectroscopic parameters. After confirming the reproducibility of the DFT methods for elucidating the equilibrium structures and Ir Mössbauer isomer shifts of the octahedral Ir complexes, the isomer shifts and quadrupole splitting values of Vaska's complexes and their oxidative adducts were calculated. A bond critical point analysis revealed that the tendency in the isomer shifts was correlated with the strength of the covalent interaction in the coordination bonds. In an electric field gradient (EFG) analysis of the oxidative adducts, the sign of the principal axis was found to be positive for the complex with YZ = Cl and negative for the complex with YZ = H. This reversal of the sign of the EFG principal axis was caused by the difference in the electron density distribution for the coordination bonds between Ir and YZ, according to a density of states analysis.
在本研究中，密度泛函理论（DFT）计算被应用于化学式为 -[IrX(CO)(PPh)] 的瓦卡斯配合物及其与包括H在内的小分子（YZ）形成的氧化加合物，即 -[IrClYZ(CO)(PPh)]，以成功地将配合物的电子态与相应的铱穆斯堡尔光谱参数相关联。在确认了DFT方法用于阐明八面体铱配合物的平衡结构和铱穆斯堡尔同质异能位移的可重复性之后，计算了瓦卡斯配合物及其氧化加合物的同质异能位移和四极分裂值。键临界点分析表明，同质异能位移的趋势与配位键中共价相互作用的强度相关。在对氧化加合物的电场梯度（EFG）分析中，发现对于YZ = Cl的配合物，主轴的符号为正，而对于YZ = H的配合物，主轴的符号为负。根据态密度分析，EFG主轴符号的这种反转是由铱与YZ之间配位键的电子密度分布差异引起的。
