Vincenzini Brett D, Yu Xiaojuan, Paloc Sébastien, Smith Patrick W, Gupta Himanshu, Pandey Pragati, Kent Greggory T, Ordonez Osvaldo, Keller Taylor, Gau Michael R, Bacon Alexandra M, Minasian Stefan G, Hayton Trevor W, Autschbach Jochen, Schelter Eric J
Vagelos Laboratory for Energy Science and Technology, Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.
Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY, USA.
Nat Chem. 2025 Apr 23. doi: 10.1038/s41557-025-01791-2.
Metal-ligand bonding interactions for f-element compounds are typically highly polarized with only minor covalent character. Whereas the 5d/6d orbitals are known to be chemically accessible for dative bonding, recent quantum chemical and spectroscopic analyses have indicated appreciable 4f/5f-orbital involvement in certain metal-ligand bonds. However, 4f-orbital covalency has not been compellingly linked to distinctive modes of chemical reactivity via rigorous comparative study and mechanistic investigation. Here a series of M-cyclopropenyl complexes (M = Ti, Zr, Ce, Hf, Th) are described, wherein the cerium congener exhibits a 4f-covalent Ce=C interaction, causing a ring-opening isomerization reaction through a single-crystal-to-single-crystal transformation. The results provide evidence for 4f-orbital covalency by demonstrating its expression in the reactivity of an f-element complex within an isostructural series of tetravalent d- and f-block metal complexes. They also provide new directions for the study of orbital covalency effects of molecular compounds in solid-state chemical transformations.
f 元素化合物的金属 - 配体键合相互作用通常具有高度极化性，仅具有轻微的共价特征。虽然已知 5d/6d 轨道可用于配位键合的化学过程，但最近的量子化学和光谱分析表明，在某些金属 - 配体键中 4f/5f 轨道也有显著参与。然而，通过严格的比较研究和机理研究，4f 轨道的共价性尚未与独特的化学反应模式形成令人信服的联系。本文描述了一系列 M - 环丙烯基配合物（M = Ti、Zr、Ce、Hf、Th），其中铈的同系物表现出 4f 共价的 Ce = C 相互作用，通过单晶到单晶的转变引发开环异构化反应。这些结果通过在同结构的四价 d 族和 f 族金属配合物系列中展示 f 元素配合物的反应性中的 4f 轨道共价性表达，为 4f 轨道共价性提供了证据。它们还为研究分子化合物在固态化学转化中的轨道共价性效应提供了新的方向。
