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

Abstract

Three-dimensional open-framework metal selenites of the formula, [H₂N(CH₂)₄NH₂]_0.5[M(HSeO₃)(Se₂O₅)] (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 MO₆ dimers along with Se₂O₅ and HSeO₃ 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 (M₂Se₂) and 6-membered (M₂Se₄) rings.