Gardner Joel G, Schneider Joseph E, Anderson John S
Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States.
Inorg Chem. 2021 Sep 20;60(18):13854-13860. doi: 10.1021/acs.inorgchem.1c01022. Epub 2021 Jul 1.
Late-transition-metal oxo and imide complexes play an important role in the catalytic functionalization and activation of small molecules. An emerging theme in this area over the past few decades has been the use of lower coordination numbers, and pseudotetrahedral geometries in particular, to stabilize what would otherwise be highly reactive species. However, the bonding structure in d oxo and imide complexes in this geometry is ambiguous. These species are typically depicted with a triple bond; however, recent experimental evidence suggests significant empirical differences between these complexes and other triply bonded complexes with lower d counts. Here we use a suite of computational orbital localization methods and electron density analyses to probe the bonding structure of isoelectronic d Co oxo and imide complexes. These analyses suggest that a triple-bond description is inaccurate because of a dramatically weakened σ interaction. While the exact bond order in these cases is necessarily dependent on the model used, several metrics suggest that the strength of the metal-O/N bond is most similar to that of other formally doubly bonded complexes.
晚期过渡金属氧代和亚胺配合物在小分子的催化官能团化和活化中起着重要作用。在过去几十年里，该领域一个新兴的主题是使用较低的配位数，特别是假四面体几何结构，来稳定那些否则会具有高反应活性的物种。然而，这种几何结构的d-氧代和亚胺配合物中的键合结构尚不明确。这些物种通常被描述为具有三键；然而，最近的实验证据表明，这些配合物与其他具有较低d电子数的三键配合物之间存在显著的经验差异。在这里，我们使用一系列计算轨道定域化方法和电子密度分析来探究等电子d钴氧代和亚胺配合物的键合结构。这些分析表明，由于σ相互作用显著减弱，三键描述并不准确。虽然在这些情况下的确切键级必然取决于所使用的模型，但一些指标表明，金属 - O/N键的强度与其他形式上为双键的配合物最为相似。
