*2.3. Single-Crystal X-ray Diffraction (SC-XRD)*

Crystals of **TS3w** suitable for SC-XRD analysis were obtained alternatively from slow evaporation of an EtOH solution of **TS3w** and from stratification of diethylether over an EtOH solution of **TS3w**.

Single crystal data were collected at 220 K with a Bruker (US) D8 Venture diffractometer equipped with a Photon II detector, using a CuKα microfocus radiation source (λ = 1.54184 Å). The intensity data were integrated from several series of exposure frames

covering the sphere of reciprocal space. Data reductions were performed with APEX3 (III). Absorption corrections were applied using the program SADABS [27]. The structures were solved by intrinsic phasing with the program SHELXT (1.0.825/28 January 2017). Fourier analysis and refinement were performed by the full-matrix least-squares methods based on F<sup>2</sup> using SHELXL-2017 [28,29] implemented in Olex2 software (1.3) [30]. Non-H atoms were refined anisotropically, H atoms were placed in calculated positions and refined with a riding model. Crystallographic data can be found in Supplementary Materials, Table S1.

CCDC 2124344 contains the supplementary crystallographic data for this paper.
