Reversible Activation of Water by an Air‐ and Moisture‐Stable Frustrated Rhodium Nitrogen Lewis Pair

[Cp*Rh(κ3N,N′,P‐L)][SbF6] (Cp*=C5Me5), bearing a guanidine‐derived phosphano ligand L, behaves as a “dormant” frustrated Lewis pair and activates H2 and H2O in a reversible manner. When D2O is employed, a facile H/D exchange at the Cp* ring takes place through sequential C(sp3)−H bond activation. And the beast wakes up! The dormant FLP complex (see scheme) can be isolated as an air‐ and moisture‐stable solid. But, in solution, the dissociated active FLP state is easily accessible and the complex activates H2O and H2, under soft conditions, in a reversible manner. Concurrently, a facile H/D exchange at the Cp* ligand, associated with water activation, was observed.