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Three-Dimensional Open-Framework Cobalt(II) Phosphates by Novel Routes

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posted on 07.03.2000, 00:00 by Srinivasan Natarajan, S. Neeraj, Amitava Choudhury, C. N. R. Rao
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) Å3, 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)o V = 4223.4 (2) Å3, 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.