Gases with sufficient Lewis acidity or basicity form weak and reversible complexes with carefully selected ionic liquids. We have prepared ionic liquid complexes with PH3 and BF3 that provide large gas capacities in the liquid phase at low pressures.

We present a combined theoretical and experimental study on weak chemical complexation between PH(3) and a few selected Cu(I)- and Al-based ionic liquids (ILs). PH(3) molecules were found to covalently bind with the cationic sites of the ILs. Effects of cations, anions, ion pairing, and solvents on the binding strength were systematically examined. The weak coordination of PH(3) on the ILs allows the PH(3) gas to be stored at near ambient conditions with a high capacity.