1. Single brown plate crystals of 1 were recrystallised from a mixture of acetonitrile and isopropanol by vapour diffusion. A suitable crystal with dimensions 0.15 × 0.12 × 0.04 mm 3 was selected and mounted on a MITIGEN holder in Paratone oil on a Diamond Light Source I-19 EH1 diffractometer. The crystal was kept at a steady T = 100.0 K during data collection. The structure was solved with the Superflip solution program using iterative methods and by using Olex2 as the graphical interface. The model was refined with ShelXL 2018/3 using full matrix least squares minimisation on F 2 . 1a. Single dark brown block-shaped crystals of 1a were recrystallised from a mixture of diethyl ether and acetonitrile by vapour diffusion. A suitable crystal 0.17 × 0.09 × 0.06 mm 3 was selected and mounted on a MITIGEN holder in Paratone oil on an Rigaku Oxford Diffraction SuperNova diffractometer. The crystal was kept at a steady T = 120.0 K during data collection. The structure was solved with the ShelXT structure solution program using the Intrinsic Phasing solution method and by using Olex2 as the graphical interface. The model was refined with version 2018/3 of ShelXL using Least Squares minimisation.