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Purification of C2H4 from an C2H4 /C2H6 mixture is one of the most challenging separation processes, which is achieved mainly through energy‐intensive, cryogenic distillation in industry. Sustainable, non‐distillation methods are highly desired as alternatives. We discovered that the fluorinated bis(pyrazolyl)borate ligand supported copper(I) complex {[(CF3)2Bp]Cu}3 has features very desirable in an olefin–paraffin separation material. It binds ethylene exclusively over ethane generating [(CF3)2Bp]Cu(C2H4). This molecular compound exhibits extremely high and record ideal adsorbed solution theory (IAST) C2H4 /C2H6 gas separation selectivity, affording high purity (>99.5 %) ethylene that can be readily desorbed from separation columns. In‐situ PXRD provides a "live" picture of the reversible conversion between [(CF3)2Bp]Cu(C2H4) and the ethylene‐free sorbent in the solid‐state, driven by the presence or removal of C2H4. Molecular structures of trinuclear {[(CF3)2Bp]Cu}3 and mononuclear [(CF3)2Bp]Cu(C2H4) are also presented. [ABSTRACT FROM AUTHOR]

A structural study of the complex aminated stereotriads [(tert-butyldimethylsilyl)oxy]-4-ethynyl-4-(1-fluorohexyl)-1,2,3-oxathiazocane-2,2-dione (1) and its reduced analogue [(tert-butyldimethylsilyl)oxy]-4-ethenyl-4-(1-fluorohexyl)-1,2,3-oxathiazocane-2,2-dione (2) revealed a k12-type second-order phase transition in 1 and phase stability of 2 over the temperature range 100-298 K. The observed phase change in 1 has been linked to the partial ordering of the extensive positional disorder of the high temperature phase upon cooling as revealed by single-crystal X-ray diffraction. The ordering breaks the translational symmetry, introduces differences in the molecular volumes of the packed species, and results in a low-temperature crystal structure with Z' = 12. The in situ powder X-ray diffraction studies suggest that the transition occurs between 237 and 180 K upon cooling, but complete amorphization in the range of 244-274 K during heating complicated the assignment of the transition temperature. The observed loss of crystallinity has been linked to the phase transition and implies that the loss of long-range order is due to the crystallites undergoing the transformation independently from one another. [ABSTRACT FROM AUTHOR]