Low Heat of Adsorption of Ethylene Achieved by Major Solid-State Structural Rearrangement of a Discrete Copper(I) Complex
Angew. Chem. 2018, 57 (50), 16442-16446
The trinuclear copper(I) pyrazolate complex [Cu3] rearranges to the dinuclear analogue [Cu2 (C2H4)2] when exposed to ethylene gas. Remarkably, the [Cu3]↔[Cu2 (C2H4)2 ] rearrangement occurs reversibly in the solid state. Furthermore, this transformation emulates solution chemistry. The bond-making and breaking processes associated with the rearrangement in the solid-state result in an observed heat of adsorption (-13±1 kJ mol-1 per Cu-C2H4 interaction) significantly lower than other Cu-C2H4 interactions (≥-24 kJ mol-1). The low overall heat of adsorption, "step" isotherms, high ethylene capacity (2.76 mmol g-1 ; 7.6 wt % at 293 K), and high ethylene/ethane selectivity (136:1 at 293 K) make [Cu3] an interesting basis for the rational design of materials for low-energy ethylene/ethane separations.