Obeng Augustine, Autschbach Jochen
Department of Chemistry, University at Buffalo State University of New York Buffalo, New York 14260-3000, United States.
J Chem Theory Comput. 2024 Jun 25;20(12):4965-4976. doi: 10.1021/acs.jctc.4c00404. Epub 2024 Jun 10.
The "dative" covalent interactions between metals and ligands in coordination compounds, i.e., metal-to-ligand and ligand-to-metal donation, are manifestations of electron delocalization and subject to errors in approximate calculations. This work addresses the extent of dative bonding/donation in a series of closed-shell transition metal complexes. Several Kohn-Sham density functionals, representing different "rungs" of approximations, along with post-Hartree-Fock methods are assessed in comparison to CCSD(T). Two widely used nonhybrid and global hybrid density functionals (B3LYP, PBE0) tend to produce notably too strong donation. Global hybrids with elevated fractions of exact exchange (40 to 50%) and the range-separated exchange functional CAM-B3LYP tend to perform better for the description of the donation. The performance of a double-hybrid functional is found to be quite satisfactory, correcting errors seen in MP2 calculations. A fast approximate coupled-cluster model (DLPNO-CCSD) also gives a reasonable description of the donation, with a tendency to underestimate its extent.
配位化合物中金属与配体之间的“给体”共价相互作用，即金属到配体和配体到金属的电子给予，是电子离域的表现，并且在近似计算中容易出现误差。这项工作研究了一系列闭壳层过渡金属配合物中给体键合/电子给予的程度。与CCSD(T)相比，评估了几种代表不同近似“层级”的Kohn-Sham密度泛函以及后Hartree-Fock方法。两种广泛使用的非杂化和全局杂化密度泛函（B3LYP、PBE0）往往会产生明显过强的电子给予。具有较高精确交换分数（40%至50%）的全局杂化和范围分离交换泛函CAM-B3LYP在描述电子给予方面往往表现更好。发现双杂化泛函的性能相当令人满意，纠正了MP2计算中出现的误差。一种快速近似耦合簇模型（DLPNO-CCSD）也能对电子给予给出合理描述，但有低估其程度的趋势。
