Theoretical and Computational Biomolecular Physics Group, Department of Physics, Purdue University, West Lafayette, Indiana 47907-2036, USA.
J Phys Chem A. 2009 Aug 13;113(32):9150-6. doi: 10.1021/jp8107667.
Iron nitrosyl complexes with {FeNO}7 (S = 3/2) configuration have a complex electronic structure and display remarkable but not fully understood spectroscopic properties. In particular, {FeNO}7 (S = 3/2) complexes have very large zero-field splittings (ZFSs), which arise from strong spin-orbit coupling, a relativistic effect. The accurate prediction and microscopic interpretation of ZFSs in transition metal complexes can aid in the interpretation of a vast amount of spectroscopic (e.g., Mössbauer and electron paramagnetic resonance) and other experimental (e.g., magnetic susceptibility) data. We report the accurate calculation of the sign and magnitude of ZFSs for a set of representative diatomic molecules based on a combined spin density functional theory and perturbation theory (SDFT-PT) methodology. In addition, we apply the SDFT-PT methodology to accurately calculate the magnitude and sign of the ZFS parameters of an {FeNO}7 (S = 3/2) complex and to interpret its spectrocopic data. We find that the principal component Dzz of the ZFS tensor is very closely oriented along the Fe-N(O) bond, indicating that nitric oxide dominates the very intricate electronic structure of the {FeNO}7 (S = 3/2) compound. We find a direct correlation between electronic delocalization along the Fe-N(O) bond, which is due to pi-bonding, and the large ZFS.
具有 {FeNO}7 (S = 3/2) 构型的铁亚硝酰配合物具有复杂的电子结构，并显示出显著但尚未完全理解的光谱性质。特别是，{FeNO}7 (S = 3/2) 配合物具有非常大的零场分裂 (ZFS)，这是由于强自旋轨道耦合，这是一种相对论效应。准确预测和微观解释过渡金属配合物中的 ZFS 可以帮助解释大量光谱（例如穆斯堡尔和电子顺磁共振）和其他实验（例如磁化率）数据。我们报告了基于自旋密度泛函理论和微扰理论 (SDFT-PT) 方法的一组代表性双原子分子的 ZFS 的符号和大小的准确计算。此外，我们应用 SDFT-PT 方法准确计算了 {FeNO}7 (S = 3/2) 配合物的 ZFS 参数的大小和符号，并解释了其光谱数据。我们发现 ZFS 张量的主分量 Dzz 非常紧密地沿着 Fe-N(O) 键取向，表明一氧化氮主导了 {FeNO}7 (S = 3/2) 化合物非常复杂的电子结构。我们发现电子离域沿着 Fe-N(O) 键的直接相关性，这是由于 pi 键合引起的，与大的 ZFS 有关。
