Cd(II) and Zn(II) coordination networks involving 6-fold acentric diamondoid structures

Two novel three-dimensional coordination polymers of Zn(II) and Cd(II) with 1,4-bis(4-carboxypyridinium)butane (L), namely {(CdL2).4H(2)O.2ClO(4)}(n) 1 and {(ZnL2).4H(2)O.2ClO(4)}(n) 2, have been prepared by the reactions of Zn(ClO4)(2).6H(2)O and Cd(ClO4)(2).6H(2)O with L in aqueous solution, and structurally characterized. The results show that, although 1 and 2 have the same stoichiometric formula, they crystallize in different space groups with 1 in P (4) over bar n2 and 2 in P4(2)22. In both compounds, the metal atoms are each linked by L bridges to four adjacent metal centres, thus forming diamondoid networks with 6-fold penetration. The large void spaces formed in the network are filled with perchlorate anions and (H2O)(4) clusters.