The new high-quality crystal structure of the pirEt-alpha isomer of compound in its high-pressure phase has been determined by means of single-crystal X-ray diffraction at 1.1 GPa, using tailor-made, theoretically calculated aspherical atomic scattering factors.
The dataset consists of 1 zip file with
a) the final structure model obtained from X-ray diffraction data in crystallographic format (a .cif file)
and
b) the final set of atomic scattering factors tabularized in a .tscb file.
The set of two files together is necessary to automatically repeat the aspherical crystal structure refinement by uploading them into Olex2.
Olex2 in its standard version is open-source software, distributed under BSD licence (https://www.olexsys.org/olex2/docs/getting-started/installing-olex2/open-source/) and thus free to use.
##Structure solution and refinement
Structures were solved using SXELXS/SHELXT and refined using SHELXL (Sheldrick, 2015) within Olex2 graphical environment (Dolomanov et al., 2009; Bourhis et al., 2015). The hydrogen atom positions were constrained to their closest carbons and had their atomic displacement parameters defined using the riding approximation. In the case of the multi-crystal approach, no further restraints or constraints were necessary. The structure of the new monoclinic pyrEt-α phase at 1.10(3) GPa was finally subjected to the Hirshfeld Atom Refinement (HAR) using NoSpherA2, an implementation of NOn-SPHERical atomic form factors in Olex2 (Kleemiss et al., 2021). The electron density was calculated from a Gaussian basis set single determinant SCF wavefunction for a fragment covering twice the monoclinic asymmetric unit in the exact experimental geometry. Calculations were performed with ORCA 5.0 (Neese et al., 2020) using the DFT approach with R2SCAN functional, x2c-TZVP basis set, and DKH2 relativistic correction. The hydrogen atom positions remained constrained using the riding approximation.
