Smartlab x ray diffraction system

X-ray diffraction was performed on bulk samples using a Rigaku Smartlab X-ray diffraction system with Cu K- $\alpha$ radiation to identify the compositions. Phase purity of the samples was confirmed via peak matching within the ICSD database. Lattice parameters were obtained via Rietveld refinement using the PDXL2 software (version 2) for samples both before and after annealing. The values and uncertainties of the lattice parameters are included in Supplemental Tables S1–S4.

The single‐crystal diffraction data of [3.2.1‐abco]ReO₄ at 373, 300, 253, and 100 K by using Rigaku Oxford diffractometer with Cu‐Kα radiation (λ = 1.54178 Å) was obtained. The structures by direct methods and refined them by the full‐matrix method based on the SHELXTL software package was solved. The C, N, Re, and O atoms were refined anisotropically. The X‐ray crystallographic structures have been deposited at the Cambridge Crystallographic Data Centre (deposition numbers CCDC 2252194–2252197) and can be obtained free of charge from the CCDC via www.ccdc.cam.ac.uk/getstructures. Powder X‐ray diffraction (PXRD) patterns were collected by using a Rigaku Smartlab X‐ray diffraction system with Cu Kα radiation. For PXRD patterns, the recorded 2θ angles range is 5–50°, and the step size was 0.02°.