Single crystal X-ray diffraction. Single crystals of 1 (CCDC 2321385), 2 (CCDC 2321386), 3 (CCDC 2321387) and 4 (CCDC 2321388) were analyzed by single crystal X-ray diffraction. For each compound, a single crystal of suitable quality was collected with a loop, cryoprotected by dipping it in glycerol, and then frozen in liquid nitrogen for storage. Using the facility's robot, single crystals of 1, 2 and 4 were measured at 100 K at XRD1 beamline (Elettra, Trieste, Italy), while 3 was measured at 100 K at XRD2 beamline (Elettra, Trieste, Italy). The rotating crystal method was used to collect diffraction data using synchrotron radiation with a wavelength 0.7000 Å for the data collected at XRD1 and 0.6199 Å for the data collected at the XRD2. For further details on the structure solution and refinement, see ESI. Mercury 26 was used as a crystal structure drawing tool. to draw Deposition Numbers CCDC 2321385-8 refer to the crystallographic data deposited at the Cambridge Crystallographic Data Centre (CCDC).