Template Synthesis and Structure of a Three-Dimensional Bimetallic Phosphate

Introducing cobalt into the Zn-P-O-amine system and using oxalates as starting materials, an amine-containing open-framework zinc cobalt phosphate, C₂N₂H₁₀]Co_4.2Zn_1.8 (PO₄)₄(HPO₄)]·H₂O (1), has been hydrothermally synthesized. It crystallizes in monoclinic space group C2/c (No. 15) with cell parameters a=19.214(8) Å, b=5.0152(17) Å, c=21.175(8) Å, β=103.06(3)°, V=1987.7(13) ų, Z=4, D_cal=3.078 g cm⁻³. The structure contains two sets of M-O-M linkage: M-O-M dimer and unusual infinite helical -M-O-M- chain. Connecting the dimers by phosphates leads to three-membered ring chains. The linking of the helical chains by PO₄ groups results in a sheet structure. Using the three-membered ring chains as pillars, stacking of the sheets gives rise to a three-dimensional tunnel structure.