Three-dimensional open-framework cobalt (II) phosphates by novel routes

Abstract

Two new three-dimensional open-framework cobalt phosphates, [C₂N₂H₁₀]₂[Co₄(PO₄) ₄]H₂O, I, and [C₄N₃H₁₆] ₃[Co₆(PO₄)₅(HPO₄)₃ ]H₂O, II, have been prepared by the reaction of amine phosphates with Co²⁺ salts. I could also be prepared by the reaction of the cobalt tris amine complex with H₃PO₄. The crystal data for I and II are as follows: phosphate I, orthorhombic, space group P2₁2₁2₁ (no. 19), a = 10.277 (1) Å, b = 10.302 (1) Å, c = 18.836 (1) Å, V = 1994.2 (2) ų, Z = 4; phosphate II, monoclinic, space group P2₁/c (No. 14), a = 31.950 (1) Å, b = 8.360 (1) Å, c = 15.920 (1) Å, β = 96.6 (1)° V = 4223.4 (2) ų, Z = 4. The structures of both I and II are constructed from alternating CoO₄ and PO₄ tetrahedra. The connectivity leads to the formation of eight-membered channels in all the crystallographic directions resembling the aluminosilicate zeolite, merlinoite in the case of I and to a rather large, one-dimensional 16-membered channel in II. Strong hydrogen-bond interactions involving the amine and framework oxygens are present in both I and II.