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NMR Crystallography: Evaluation of Hydrogen Positions in Hydromagnesite by 13 C{ 1 H} REDOR Solid‐State NMR and Density Functional Theory Calculation of Chemical Shielding Tensors
Author(s) -
Cui Jinlei,
Olmsted David L.,
Mehta Anil K.,
Asta Mark,
Hayes Sophia E.
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201813306
Subject(s) - density functional theory , solid state nuclear magnetic resonance , chemistry , hydrogen , crystallography , anisotropy , nuclear magnetic resonance spectroscopy , chemical shift , carbon 13 nmr , nuclear magnetic resonance , computational chemistry , stereochemistry , physics , organic chemistry , quantum mechanics
Solid‐state NMR measurements coupled with density functional theory (DFT) calculations demonstrate how hydrogen positions can be refined in a crystalline system. The precision afforded by rotational‐echo double‐resonance (REDOR) NMR to interrogate 13 C– 1 H distances is exploited along with DFT determinations of the 13 C tensor of carbonates (CO 3 2− ). Nearby 1 H nuclei perturb the axial symmetry of the carbonate sites in the hydrated carbonate mineral, hydromagnesite [4 MgCO 3 ⋅Mg(OH) 2 ⋅4 H 2 O]. A match between the calculated structure and solid‐state NMR was found by testing multiple semi‐local and dispersion‐corrected DFT functionals and applying them to optimize atom positions, starting from X‐ray diffraction (XRD)‐determined atomic coordinates. This was validated by comparing calculated to experimental 13 C{ 1 H} REDOR and 13 C chemical shift anisotropy (CSA) tensor values. The results show that the combination of solid‐state NMR, XRD, and DFT can improve structure refinement for hydrated materials.