Hydrogen adsorption in dehydrated variants of the cyano-bridged framework compounds A(2)Zn(3)[Fe(CN)(6)](2)center dot xH(2)O (A = H, Li, Na, K, Rb)

The impact of coordinatively-unsaturated alkali- metal ions on hydrogen adsorption is studied in dehydrated variants of the compounds A(2)Zn(3)[Fe(CN)(6)](2 center dot)xH(2)O (A = H, Li, Na, K, Rb), revealing maximum adsorption enthalpies that vary from 7.7 kJ mol(-1) for A = Na to 9.0 kJ mol(-1) for A = K.