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Data for An XRD and NMR crystallographic investigation of the structure of 2,6-lutidinium hydrogen fumarate Emily K. Corlett (8275893) Helen Blade (1600069) Leslie P. Hughes (1357650) Philip J. Sidebottom (3060630) David Walker (36297) Richard I. Walton (1328463) Steven P. Brown (1296819) Fumaric acid -- Research Crystallography Magnetic resonance Migrated from ePrints Fumarate is a pharmaceutically acceptable counterion often used to modify the biophysical properties of active pharmaceutical ingredients (APIs) through salt formation. With 2,6-lutidine (2,6-dimethylpyridine), fumaric acid forms the salt 2,6-lutidinium hydrogen fumarate. An NMR crystallography approach was employed to investigate the salt structure and the intermolecular interactions involved in its formation and stability. The crystallographic unit cell was determined by both single crystal XRD (SXRD) and synchrotron powder X-ray diffraction (PXRD) to contract at low temperature with a skew in the β angle. Density functional theory (DFT)-based geometry optimisations were found partially to replicate this. A second room temperature structure was also identified which exhibited a similar skew of the β angle as the low temperature structure. DFT calculation was also employed, alongside 2D 1H double-quantum (DQ) magic angle spinning (MAS) and 14N-1H HMQC MAS NMR spectra, to investigate the hydrogen bonding network involved in the structure. DFT-based gauge-including projector-augmented wave (GIPAW) calculations highlighted both strong N+-H···O− and O-H···O intermolecular hydrogen bonds between the molecules, as well as several weaker CH···O hydrogen bonds. Both PXRD and solid-state MAS NMR, supported by thermal gravimetric analysis (TGA) and solution-state NMR analysis, show formation of fumaric acid within samples over time. This was evidenced by the identification of reflections and peaks associated with crystalline fumaric acid in the PXRD pattern and in 1H MAS and 13C cross polarization (CP) MAS solid-state NMR spectra, respectively.<br><br>The names of all raw data files from the solid-state NMR measurements and different calculations are presented: 1.Raw files for the PXRD experiments 2.Raw files from NMR experiments 3.For the calculations, the initial CIF file, the CIF file after geometry optimisation (with and without varying unit cell) and the magres-files for the full crystal structure and isolated molecules 4.TGA and DSC data 2019-05-20T00:00:00Z Dataset Dataset 10.82444/warw.33779686.v1 https://figshare.com/articles/dataset/Data_for_An_XRD_and_NMR_crystallographic_investigation_of_the_structure_of_2_6-lutidinium_hydrogen_fumarate/33779686 CC BY 4.0