The reaction of Cu(ClO4)2·6H2O with t-BuP(O)(OH)2 and 3,5-(CF3)2PzH in the presence of triethylamine afforded the dodecanuclear cage {[Et 3NH]2[Cu12(μ-3,5-(CF3) 2Pz)6(μ3-OH)6(μ-OH) 3(μ3-t-BuPO3)2(μ6- t-BuPO3)3][t-BuPO2OH]-[C6H 5CH3]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(NO 3)2·3H2O, t-BuP(O)(OH)2, 3,5-dimethylpyrazole, and triethylamine afforded another dodecanuclear cage [Cu12(μ-DMPz)8(η1-DMPzH) 2(μ4-O)2(μ3-OH) 4(μ3-t-BuPO3)4]·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. © 2008 American Chemical Society.