Three-dimensional yttrium oxalates possessing large channels

Abstract

Two new open-framework yttrium oxalates have been prepared, for the first time, employing hydrothermal methods in the presence of organic amines. The crystal data for these oxalates are as follows: I, [C₆N₂H₁₆]_0.5[Y(H₂O) (C₂O₄)₂]·2H₂O, triclinic, space group P(-1) (no. 2), a = 8.229(3), b = 9.739(1), c = 9.754(3) Å, α = 60.74(1), β = 72.36(1), γ = 84.67(1)°, V = 648.5(1) ų, Z = 2, M = 377.1, D_calc = 1.931 g cm^-3, μ= 4.554 mm^-1, Mo Kα, R₁ = 0.054, wR₂ = 0.13; II, [C₅N₂H₁₂] [Y(C₂O₄)₂], monoclinic, space group Cc (no. 9), a = 11.552(1), b = 17.168(1), c = 8.719(1) Å, β = 130.64(1)°, V = 1312.1(1) ų, Z = 2, M = 365.1, D_calc = 1.848 g cm^-3, μ = 4.48 mm^-1, Mo Kα, R₁ = 0.023, wR₂ = 0.057. The Y atom is 9-coordinated in I, forming a D_3h triply capped trigonal prism, and 8-coordinated in II, forming a square antiprism. The three-dimensional framework structures of I and II are built up by in-plane linkages between the Y and the oxalate moieties, forming layers with 12-membered honeycomb-like apertures, pillared by another oxalate in an out-of-plane manner. While I possesses channels along all the crystallographic directions, II has channels only in one direction. Adsorption studies indicate that water and methanol can be reversibly adsorbed in I.