Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States.
Inorg Chem. 2020 Oct 19;59(20):15410-15420. doi: 10.1021/acs.inorgchem.0c02405. Epub 2020 Oct 8.
The oxidation state (OS) of metals and ligands in inorganic complexes may be defined by carefully curated rules, such as from IUPAC, or by computational procedures such as the effective oxidation state (EOS) or localized orbital bonding analysis (LOBA). Such definitions typically agree for systems with simple ionic bonding and innocent ligands but may disagree as the boundary between ionic and covalent bonds is approached, or as the role of ligand noninnocence becomes nontrivial, or high oxidation states of metals are supported by heavy dative bonding, and so on. This work systematically compares IUPAC, EOS, and LOBA across a series of complexes where OS assignment is challenging. These systems include high-valent transition metal oxides, transition metal complexes with noninnocent ligands such as dithiolate and nitrosyl, metal sulfur dioxide adducts, and two transition metal carbene complexes. The differences in OS assignment by the three methods are carefully discussed, demonstrating the synergy between EOS and LOBA. In addition, a clarity index for LOBA OS assignments is introduced that provides an indication of whether or not its predictions are close to the ionic-covalent boundary.
金属和无机配合物中配体的氧化态（OS）可以通过精心制定的规则来定义，例如 IUPAC 规则，或者通过有效氧化态（EOS）或局域轨道成键分析（LOBA）等计算程序来定义。对于具有简单离子键和无辜配体的系统，这些定义通常是一致的，但随着离子键和共价键之间的界限接近，或者配体非中性的作用变得重要，或者高价金属由重的给予键支持，等等，它们可能会产生分歧。这项工作系统地比较了 IUPAC、EOS 和 LOBA 在一系列 OS 赋值具有挑战性的配合物中。这些系统包括高价过渡金属氧化物、具有非无辜配体的过渡金属配合物，如二硫代和亚硝酰基、金属二氧化硫加合物以及两个过渡金属卡宾配合物。三种方法在 OS 赋值上的差异进行了仔细的讨论，展示了 EOS 和 LOBA 之间的协同作用。此外，还引入了 LOBA OS 赋值的清晰度指数，该指数提供了其预测是否接近离子-共价边界的指示。
