Organically templated three-dimensional open-framework metal selenites with a diamondoid network

Three-dimensional open-framework metal selenites of the formula, [H(2)N(CH(2))(4)NH(2)](0.5)[M(HSeO(3))(Se(2)O(5))] (M = Zn, Co or Ni), containing both selenite and diselenite units and intersecting 10-membered channels, have been prepared hydrothermally in the presence of piperazine. The compounds are isomorphous and crystallize in the P-1 space group. The structure is built up of MO(6) dimers along with Se(2)O(5) and HSeO(3) units, the first two forming sheets, which are connected by the selenite units to yield a three-dimensional non-interpenetrating diamondoid network. The 10-membered channels have an unusual structure, being formed by 4-membered (M(2)Se(2)) and 6-membered (M(2)Se(4)) rings.