Cubic and rhombohedral heterobimetallic networks constructed from uranium, transition metals, and phosphonoacetate: new methods for constructing porous materials

Four heterobimetallic U(VI)/M(II) (M = Mn, Co, Cd) carboxyphosphonates have been synthesized. M-2[(UO2)(6)(PO3CH2CO2)(3)O-3(OH)(H2O)(2)]center dot 16H(2)O (M = Mn(II), Co(II), and Cd(II)) adopt cubic three-dimensional network structures with large cavities approximately 16 angstrom in diameter that are filled with co-crystallized water molecules. [Cd-3(UO2)(6)(PO3CH2CO2)(6)(H2O)(13)]center dot 6H(2)O forms a rhombohedral channel structure with hydrated Cd(II) within the channels. The cubic compound (Co) displays differential gas absorption with a surface area for CO2 uptake of 40 m(2) g(-1) at 273 K, and no uptake of N-2 at 77 K.