Phung Quan Manh, Domingo Alex, Pierloot Kristine
Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven, 3001, Belgium.
Chemistry. 2018 Apr 6;24(20):5183-5190. doi: 10.1002/chem.201704441. Epub 2017 Nov 30.
The structures and spin-state energetics of two di-iron(II) complexes based on thiadiazole and oxadiazole ligands in different crystals were studied by using density functional theory and second-order perturbation theory based on the density matrix renormalization group approach (DMRG-CASPT2). When taking into account all different contributions to the relative energy, our theoretical approach is capable of providing results that are in excellent agreement with established experimental data. In all cases, we correctly describe the ground state of the complexes as well as predict their spin-crossover behavior. A comparison between the two complexes in the gas phase and in different crystals shows how the structures change by moving from the gas phase to different crystals and reveals a large impact of the crystal stabilization on the relative spin-state energy. This theoretical work also demonstrates the applicability of the DMRG-CASPT2 approach to quantitatively study the spin-state energetics of multinuclear transition-metal complexes.
利用基于密度矩阵重整化群方法的密度泛函理论和二阶微扰理论（DMRG-CASPT2），研究了两种基于噻二唑和恶二唑配体的二价铁（II）配合物在不同晶体中的结构和自旋态能量学。当考虑到对相对能量的所有不同贡献时，我们的理论方法能够提供与已有的实验数据高度吻合的结果。在所有情况下，我们都正确地描述了配合物的基态，并预测了它们的自旋交叉行为。对这两种配合物在气相和不同晶体中的比较表明，从气相到不同晶体时结构是如何变化的，并揭示了晶体稳定化对相对自旋态能量的巨大影响。这项理论工作还证明了DMRG-CASPT2方法在定量研究多核过渡金属配合物自旋态能量学方面的适用性。
