Single crystal X-ray diffraction data were collected at 160.0(1) K on a Rigaku OD Supernova/Atlas diffractometer for compounds 2 and 8 using the Cu Kα radiation (λ = 1.54184 Å) from a dual wavelength X-ray source and an Oxford Instruments Cryojet XL cooler. For each analysis the selected suitable single crystal was mounted using polybutene oil on a flexible loop fixed on a goniometer head and immediately transferred to the diffractometer. Pre-experiment, data collection, data reduction and analytical absorption correction 1 were performed with the program suite CrysAlisPro (version 1.171.43.143a, Rigaku Oxford Diffraction Ltd, Yarnton, Oxfordshire, England). Using Olex2, 2 the structure was solved with the SHELXT 3 small molecule structure solution program and refined with the SHELXL program package 4 by full-matrix least-squares minimization on F 2 . PLATON 5 was used to check the result of the X-ray analysis.