Cerium under the lens

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In this month’s ‘in your element’ article (subscription required), Eric Schelter from the University of Pennsylvania draws our attention to cerium, an element that serves a variety of commercial and industrial applications, yet presents chemists with some rather peculiar challenges.



Although it is one of the rare-earth elements, cerium is fairly abundant in the Earth’s crust, and widely used for various purposes. The oxide ceria (CeO2), for example, is a common abrasive for the polishing of surfaces ranging from optical lenses to electronic displays. The reason it is particularly efficient is that, in addition to a mechanical polishing action, it attacks the basic sites of surfaces.

Most of cerium’s applications rely on its interconversion between the +3 and +4 oxidation states. I’ll let you read in the article how “hydrocarbon fuels encounter element 58 at both the beginning and the end of their useful life”, and which cerium compound represents a “drastic ‘nuclear option’ for oxidation reactions” in synthetic chemistry.

There is much to explore regarding the reactivity of cerium, and even in terms of the electronic structure of some of its compounds — this is an aspect that I find particularly intriguing. Take cerocene, a seemingly straightforward complex that consists of a cerium centre sandwiched between two C8H8 ligands to form an eclipsed sandwich complex. Experimental characterization and computational calculations point to a multiconfigurational ground state, for which it’s proving rather difficult to determine unambiguously the Ce(III) and Ce(IV) contributions. As Schelter puts it, “this deceptively simple compound represents a stimulating case where the very human concept of a formal oxidation state fails to capture the essential essence of a molecule.”

Anne Pichon (Senior Editor, Nature Chemistry)

Anne Pichon

Senior Editor, Nature Chemistry, Springer Nature

Anne received a broad training in chemistry at the National Graduate School of Chemistry in Montpellier, France. She then focused on inorganic and supramolecular chemistry and obtained her MPhil and PhD degrees from the Queen's University Belfast, UK, investigating porous coordination polymers for host–guest applications. After an internship with Nature Reviews Drug Discovery, Anne moved to John Wiley and Sons in 2007 as an assistant editor of the Society of Chemical Industry journals. She joined Nature Chemistry in October 2008, and was initially based in Tokyo where she also worked on other publishing projects with Nature Asia-Pacific. In April 2013, Anne relocated to the London office and now works full time on the journal.