In addition to the structural/chemical space, we examined the performance space occupied by the K-C2 dataset to understand the current state of the literature. Examining the ethane and ethylene adsorption behavior, we observe that some K-C2 structures exhibit high uptakes (> 6 mmol/g) at 101 kPa and 273 K for both adsorbates, enabling the potential for high swing capacities (Figure ). Swing, or working, capacity is the difference in the amount adsorbed under adsorption and desorption conditions. This amount is not necessarily equal to the total amount adsorbed since conditions sufficient for complete regeneration are not typically obtained in real operations. Despite the high uptakes, the highest ideal ethane selectivity in the dataset is only 1.7, underscoring the difficulty of making ethane-selective adsorbents. We note that higher selectivities have been reported, such as the current state-of-the-art iron-peroxo MOF reported by Li et al. Articles associated with this MOF were not found in our initial search of the literature during dataset curation, a limitation of the present data set, but such articles will be included in future updates. Surprisingly, the average ethane adsorption is higher than the average ethylene adsorption (3.25 and 2.79 mmol/g, respectively), even though ethane has a kinetic diameter of 4.4 Å and ethylene has a kinetic diameter of 4.2 Å. This is likely because there is not complete overlap between structures for which ethane adsorption and structures for which ethylene adsorption were measured. There is also variability in the manner in which adsorption occurs. Most structures exhibit either Henry-like or Langmuir-like behavior (Figure ). We note that we cannot definitively assign an isotherm classification for any isotherm in our dataset since adsorption is not measured up to the saturation pressure of the adsorbate. Despite this limitation, we note that some structures also exhibit more complex adsorption behaviors such as a stepped Type IV-like shape (Figure , lower left) or convex Type V-like shape (Figure