Actinide-Oxygen Multiple Bonds from Air: Synthesis and Characterization of a Thorium Oxo Supported by Redox-Active Ligands

J Am Chem Soc. 2022 Sep 28;144(38):17423-17431. doi: 10.1021/jacs.2c04947. Epub 2022 Sep 19.

Abstract

The first non-uranyl, f-element oxo complex synthesized from dioxygen in dry air is presented in this work. The synthesis was accomplished by treating the redox-active thorium amidophenolate complex, [Th(dippap)3][K(15-c-5)2]2 (1-ap crown), with dioxygen in dry air, forming a rare terminal thorium oxo, [O═Th(dippisq)2(dippap)][K(15-c-5)2]2 (2-oxo). Compound 1-ap crown was regenerated by treating 2-oxo with potassium graphite. X-ray crystallography of 2-oxo revealed a comparatively longer bond length for the thorium-oxygen double bond when compared to other thorium oxos. As such, several thorium-oxygen single bonds were synthesized for comparison, including Th(dippisq)2(OSiMe3)2(THF) (4-OSiMe3), Th(OSiMe3)4(bipy)2 (5-OSiMe3), and [Th(OH)2 (dippHap)4][K(15-c-5)2]2 (6-OH). Full spectroscopic and structural characterization of the complexes was performed via 1H NMR spectroscopy, X-ray crystallography, EPR spectroscopy, and electronic absorption spectroscopy as well as SQUID magnetometry, which all confirmed the electronic structure of these complexes.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Graphite*
  • Ligands
  • Oxidation-Reduction
  • Oxygen / chemistry
  • Pentamidine / analogs & derivatives
  • Potassium
  • Thorium* / chemistry

Substances

  • Ligands
  • 1,3-di(4-imidazolinophenoxyl)propane
  • Thorium
  • Pentamidine
  • Graphite
  • Potassium
  • Oxygen