Hydrothermal reaction of diaminomaleonitrile and copper salts under different conditions resulted in copper cyanide coordination polymers {[Cu(H2O)(NH3)(4)][Cu-3(CN)(5)] center dot H2O}(n) (1), {(CH3)(4)N[Cu(H2O)(NH3)(4)][Cu-4(CN)(7)]}(n) (2), and {(CH3OH2)(2)[Cu-2(CN)(3)]}(n) (3). 1 and 2 are new mixed-valence Cu(I,II), two 3D organic-inorganic molecular framework complexes that exhibit ionic inclusion. 3 is an open copper cyanide framework hosting a guest molecule. Cyanides in 1, 2, and 3 are produced by in situ C-C bond cleavage of diaminomaleonitrile, and then the remaining product is oxidized to form an oxalate group. The potential porosity of the hydrated coordination polymer 3 was estimated using a computational method based on Connolly's algorithm.