Resolving the Chemical Formula of Nesquehonite via NMR Crystallography, DFT Computation, and Complementary Neutron Diffraction
Abstract
Nesquehonite is a magnesium carbonate mineral relevant to carbon sequestration envisioned for carbon capture and storage of CO₂. Its chemical formula remains controversial today, assigned as either a hydrated magnesium carbonate [MgCO₃)OH ⋅ 2H₂O]. The resolution of this controversy is central to understanding this material's thermodynamic, phase, and chemical behavior. In an NMR crystallography study, using rotational-echo double-resonance ¹³C{¹H} (REDOR), ¹³C−¹H distances are determined with precision, and the combination of ¹³C static NMR lineshapes and density functional theory (DFT) calculations are used to model different H atomic coordinates. [MgCO₃ ⋅ 3H₂O] is found to be accurate, and evidence from neutron powder diffraction bolsters these assignments. Refined H positions can help understand how H-bonding stabilizes this structure against dehydration to MgCO₃. More broadly, these results illustrate the power of NMR crystallography as a technique for resolving questions where X-ray diffraction is inconclusive.
Additional Information
This work is supported as part of the DIBBS project funded by the U.S. National Science Foundation (NSF), under Award Number 1640899. This research used the Savio computational cluster resource provided by the Berkeley Research Computing program at the University of California, Berkeley (supported by the UC Berkeley Chancellor, Vice Chancellor for Research, and Chief Information Officer). SIMPSON simulation was performed using the facilities of Washington University Center for High-Performance Computing. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We acknowledge the support of the National Institute of Standards and Technology, U. S. Department of Commerce, in providing the neutron research facilities used in this work. Prof. Craig M. Brown is also acknowledged for a scientific discussion about neutron diffraction refinement.Additional details
- Eprint ID
- 118863
- Resolver ID
- CaltechAUTHORS:20230119-170204800.1
- OAC-1640899
- NSF
- DE-AC02-06CH11357
- Department of Energy (DOE)
- Created
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2023-02-24Created from EPrint's datestamp field
- Updated
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2023-02-24Created from EPrint's last_modified field