The reaction of Cu(CIO4)(2)center dot 6H(2)O with t-BuP(O)(OH)(2) and 3,5-(CF3)(2)PzH in the presence of triethylamine afforded the dodecanuclear cage {[Et3NH](2)[Cu-12(mu-3,5-(CF3)(2)PZ)(6)(mu(3)-OH)(6)(mu-OH)(3)(mu(3)-t-B uPO3)(2)(mu(6)-t-BuPO3)(3)][t-BuPO2OH][C6H5CH3](2)) (2). The molecular structure of this cage revealed that it possesses a barrel-shaped architechture. The cage structure is built by the cumulative coordination action of phosphonate, hydroxide, and pyrazolyl ligands. A similar reaction involving Cu(NO3)(2)center dot 3H(2)O, t-BuP(O)(OH)(2), 3,5-dimethylpyrazole, and triethylamine afforded another dodecanuclear cage [Cu-12(mu-DMPz)(8)(eta(1)-DMPzH)(2)(mu(4)-O)(2)(mu(3)-OH)(4)(mu(3)-t-BuP O3)(4)]center dot 3MeOH (3). The latter is crown-shaped and is built by the coordination of pyrazole, pyrazolyl, phosphonate, hydroxide, oxide, and methanol ligands. Both of the dodecanuclear cages are efficient nucleases in the presence of magnesium monoperoxyphthalate.