2.2. Single crystal X-ray diffraction (SXRD)

A good quality optically clear 0.21 × 0.2 × 0.18 mm³ sized crystal was selected for the intensity data collection using Bruker kappa APEX II diffractometer using the MoKα radiation (λ = 0.71073 Å) source. The intensity data were collected at 20 °C. Absorption correction was carried out using the SADABS program with multi-scan method. Full-matrix least-squares refinement procedure was used for solving structures using SHELXL [³³]. All the non-hydrogen atoms were refined anisotropically and hydrogen atoms were positioned from the difference fourier maps and refined isotropically. Hydrogen atoms were placed in calculated positions, with C–H = 0.93–0.98 Å and N–H = 0.86 Å, and allowed to ride on their respective carrier atoms, U_iso(H) = 1.2U_eq(C) for CH₂, CH and NH groups.

Initial structural solution of Ib showed co-crystallized completely disordered solvent molecule (DMSO) which was modeled and refined using PART command along with a free variable. The solvent molecule is disordered over two sets of sites in a 0.515(2):0.485(3) ratio. The final refined structure was validated using PLATON [³⁴] and CheckCIF routine from IuCr. Thermal ellipsoidal image and molecular packing diagrams were generated using ORTEP [³⁵] and Mercury [³⁶]. CCDC 1997850 (Ia) and CCDC 1997851 (Ib) contain the supplementary crystallographic data. The data can be obtained free of charge from The Cambridge Crystallographic Data Center via www.ccdc.cam.ac.uk/structures. The crystallographic data and refinement parameters were listed in Table 1 .

Crystallographic table of Compounds Ia and Ib.