Using reversible polymerization and depolymerization reactions in a single crystal state, we achieved a reversible transformation from a naonocluster to a coordination polymer During the interconversion. the structural frameworks switched between nonporous hexanuclear clusters and porous double-zigzag chains; the magnetic behaviors switched between paramagnetism and metamagnetism, respectively. The microporous framework, which had 1D channels 1.9 angstrom x 3.6 angstrom in size, exhibited selective as adsorption of H-2 and CO2 over N-2.