Single crystal-to-single crystal transformations induced by ammonia–water equilibrium changes

Reversible single crystal-to-single crystal transformations were observed for the Ni(ii) complex with 5-methyl-5-phenylhydantoin. Moreover, the symmetry changes from triclinic (P1) to monoclinic (P2(1)/c). The change is induced by a disturbance of the ammonia-water equilibrium between the [solid state-solution-gas] phases, which causes an exchange of the solvent in the crystal structure.