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Two Neptunium(III) Mellitate Coordination Polymers: Completing the Series Np-Cf of Trans-Uranic An(III) Mellitates.

Nicholas B BeckZhuanling BaiJacob P BrannonDaniela Gomez MartinezDennis GrödlerBrian N LongTodd N PoeBrian M RotermundThomas E Albrecht SchmittJoseph M Sperling
Published in: Inorganic chemistry (2022)
Two neptunium(III) mellitates, 237 Np 2 (mell)(H 2 O) 9 ·1.5H 2 O ( Np-1α ) and 237 Np 2 (mell)(H 2 O) 8 ·2H 2 O ( Np-1β ), have been synthesized from 237 NpCl 4 (dme) 2 by reduction with KC 8 and subsequent reaction with an aqueous solution of mellitic acid (H 6 mell). Characterization by single-crystal X-ray crystallography and UV-vis-NIR spectroscopy confirms that the neptunium is in its +3 oxidation state and both polymorphs are isostructural to the previously reported plutonium mellitates. Of the two morphologies, Np-1α is indefinitely stable in air, while Np-1β slowly oxidizes over several months. This is due to the change in the energy of the metal-ligand charge-transfer absorption exhibited by these compounds attributed to differing numbers of carboxylate bonds to Np(III), where in Np-1β the energy is low enough to result in spontaneous oxidation.
Keyphrases
  • high resolution
  • aqueous solution
  • hydrogen peroxide
  • nitric oxide
  • mass spectrometry