Loading…

Elucidation of the Structure and Vibrational Spectroscopy of Synthetic Metaschoepite and Its Dehydration Product

We confirm that synthetic uranyl hydroxide hydrate metaschoepite [(UO)­24O­(OH)6]·5H2O is unstable against dehydration under dry conditions, and we present a structural and vibrational spectroscopic study of synthetic metaschoepite and its ambient temperature dehydration product. Complementary struc...

Full description

Saved in:
Bibliographic Details
Published in:Inorganic chemistry 2019-06, Vol.58 (11), p.7310-7323
Main Authors: Kirkegaard, Marie C, Niedziela, J. L, Miskowiec, Andrew, Shields, Ashley E, Anderson, Brian B
Format: Article
Language:English
Subjects:
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We confirm that synthetic uranyl hydroxide hydrate metaschoepite [(UO)­24O­(OH)6]·5H2O is unstable against dehydration under dry conditions, and we present a structural and vibrational spectroscopic study of synthetic metaschoepite and its ambient temperature dehydration product. Complementary structural (X-ray diffraction and neutron diffraction) and vibrational spectroscopic techniques (Raman spectroscopy, infrared spectroscopy, and inelastic neutron scattering) are used to probe different components of these species. Analysis of the dehydration product suggests that it contains both pentagonally coordinated and hexagonally coordinated uranyl ions, necessitating that some uranyl ions undergo a coordination change during the dehydration of pentagonally coordinated metaschoepite. Vibrational spectra of metaschoepite and its dehydration product are interpreted with power spectra generated from ab initio molecular dynamics trajectories, allowing assignment of all major features. We identify the uranyl symmetric stretching modes of the four distinct uranyl ions in synthetic metaschoepite and clarify the assignment of lower energy Raman modes in both structures. The coanalysis of experimental and computational data reveals a strong coupling between the uranyl stretching modes and hydroxide bending modes in the anhydrous structure, leading to the presence of several high-energy combination bands in the inelastic neutron scattering data.
ISSN:0020-1669
1520-510X
DOI:10.1021/acs.inorgchem.9b00460