Tadyszak Krzysztof, Rudowicz Czesław, Ohta Hitoshi, Sakurai Takahiro
NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 14, 61-614 Poznań, Poland; Institute of Molecular Physics, Polish Academy of Sciences, ul. M. Smoluchowskiego 17, 60-179 Poznań, Poland.
Visiting Professor: Faculty of Chemistry, A. Mickiewicz University, Umultowska 89B, 61-614 Poznań, Poland; On leave of absence from: Modeling in Spectroscopy Group, Institute of Physics, West Pomeranian University of Technology Szczecin, Al. Piastów 17, 70-310 Szczecin, Poland.
J Inorg Biochem. 2017 Oct;175:36-46. doi: 10.1016/j.jinorgbio.2017.06.006. Epub 2017 Jun 28.
The spin Hamiltonian (SH) parameters experimentally determined by EMR (EPR) may be corroborated or otherwise using various theoretical modeling approaches. To this end semiempirical modeling is carried out for high-spin (S=2) manganese (III) 3d ions in complex of tetraphenylporphyrinato manganese (III) chloride (MnTPPCl). This modeling utilizes the microscopic spin Hamiltonians (MSH) approach developed for the 3d and 3d ions with spin S=2 at orthorhombic and tetragonal symmetry sites in crystals, which exhibit an orbital singlet ground state. Calculations of the zero-field splitting (ZFS) parameters and the Zeeman electronic (Ze) factors (g=g, g=g=g) are carried out for wide ranges of values of the microscopic parameters using the MSH/VBA package. This enables to examine the dependence of the theoretically determined ZFS parameters b (in the Stevens notation) and the Zeeman factors g on the spin-orbit (λ), spin-spin (ρ) coupling constant, and the ligand-field energy levels (Δ) within the D multiplet. The results are presented in suitable tables and graphs. The values of λ, ρ, and Δ best describing Mn(III) ions in MnTPPCl are determined by matching the theoretical second-rank ZFSP b(D) parameter and the experimental one. The fourth-rank ZFS parameters (b, b) and the ρ (spin-spin)-related contributions, which have been omitted in previous studies, are considered for the first time here and are found important. Semiempirical modeling results are compared with those obtained recently by the density functional theory (DFT) and/or ab initio methods.
通过电子磁共振（电子顺磁共振）实验测定的自旋哈密顿量（SH）参数，可以使用各种理论建模方法进行验证或其他处理。为此，对四苯基卟啉氯化锰（III）（MnTPPCl）配合物中的高自旋（S = 2）锰（III）3d离子进行了半经验建模。该建模采用了为晶体中正交和四方对称位点上自旋S = 2的3d和3d离子开发的微观自旋哈密顿量（MSH）方法，这些离子呈现轨道单重态基态。使用MSH/VBA软件包，针对微观参数的广泛取值范围，计算了零场分裂（ZFS）参数和塞曼电子（Ze）因子（g = g，g = g = g）。这使得能够研究理论确定的ZFS参数b（采用史蒂文斯符号）和塞曼因子g对自旋轨道（λ）、自旋 - 自旋（ρ）耦合常数以及D多重态内配体场能级（Δ）的依赖性。结果以合适的表格和图表形式呈现。通过使理论二阶零场分裂参数b（D）与实验值匹配，确定了最能描述MnTPPCl中Mn（III）离子的λ、ρ和Δ值。此前研究中被忽略的四阶ZFS参数（b，b）和与ρ（自旋 - 自旋）相关的贡献，在此首次被考虑，并发现其很重要。将半经验建模结果与最近通过密度泛函理论（DFT）和/或从头算方法获得的结果进行了比较。
