title: Revisiting the solution structure of ceric ammonium nitrate.
abstract: Ceric ammonium nitrate (CAN) is a single-electron-transfer reagent with unparalleled utility in organic synthesis, and has emerged as a vital feedstock in diverse chemical industries. Most applications use CAN in solution where it is assigned a monomeric [Ce(IV) (NO3 )6 ](2-) structure; an assumption traced to half-century old studies. Using synchrotron X-rays and Raman spectroscopy we challenge this tradition, converging instead on an oxo-bridged dinuclear complex, even in strong nitric acid. Thus, one equivalent of CAN is recast as a two-electron-transfer reagent and a redox-activated superbase, raising questions regarding the origins of its reactivity with organic molecules and giving new fundamental insight into the stability of polynuclear complexes of tetravalent ions.
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439 (USA).
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Demars
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439 (USA).
authors.forename: Mrinal K
authors.initials: MK
authors.lastname: Bera
authors.affiliation: APS X-Ray Division, Argonne National Laboratory, Lemont, IL 60439 (USA).
authors.forename: Soenke
authors.initials: S
authors.lastname: Seifert
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439 (USA).
authors.forename: Mark R
authors.initials: MR
authors.lastname: Antonio
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439 (USA). rellis@anl.gov.
authors.forename: Ross J
authors.initials: RJ
authors.lastname: Ellis
keywords: Raman spectroscopy; X-ray absorption spectroscopy; cerium; small-angle X-ray scattering; structure elucidation