Cage-size effects on the encapsulation of P 2 by fullerenes.

The classic pnictogen dichotomy stands for the great contrast between triply bonding very stable N 2 molecules and its heavier congeners, which appear as dimers or oligomers. A banner example involves phosphorus as it occurs in nature as P 4 instead of P 2 , given its weak π-bonds or strong σ-bonds. The P 2 synthetic value has brought Lewis bases and metal coordination stabilization strategies. Herein, we discuss the unrealized encapsulation alternative using the well-known fullerenes' capability to form endohedral and stabilize otherwise unstable molecules. We chose the most stable fullerene structures from C n (n = 50, 60, 70, 80) and experimentally relevant from C n (n = 90 and 100) to computationally study the thermodynamics and the geometrical consequences of encapsulating P 2 inside the fullerene cages. Given the size differences between P 2 and P 4 , we show that the fullerenes C 70 -C 100 are suitable cages to side exclude P 4 and host only one molecule of P 2 with an intact triple bond. The thermodynamic analysis indicates that the process is favorable, overcoming the dimerization energy. Additionally, we have evaluated the host-guest interaction to explain the origins of their stability using energy decomposition analysis.