Hybrid Inorganic‐Organic Frameworks: Synthesis and Crystal Structures of RbFe(SO4)(C2O4)0.5·H2O and CsM(SO4)(C2O4)0.5·H2O (M = Mn,Fe)

Three new alkali metal transition metal sulfate‐oxalates, RbFe(SO₄)(C₂O₄)_0.5 · H₂O and CsM(SO₄)(C₂O₄)_0.5 · H₂O (M = Mn, Fe) were prepared through hydrothermal reactions and characterized by single‐crystal X‐ray diffraction, solid state UV/Vis/NIR diffuse reflectance spectroscopy, infrared spectra, thermogravimetric analysis, and powder X‐ray diffraction. The title compounds all crystallize in the monoclinic space group P2₁/c (no. 14) with lattice parameters: a = 7.9193(5), b = 9.4907(6), c = 8.8090(6) Å, β = 95.180(2)°, Z = 4 for RbFe(SO₄)(C₂O₄)_0.5 · H₂O; a = 8.0654(11), b = 9.6103(13), c = 9.2189(13) Å, β = 94.564(4)°, Z = 4 for CsMn(SO₄)(C₂O₄)_0.5 · H₂O; and a = 7.9377(3), b = 9.5757(4), c = 9.1474(4) Å, β = 96.1040(10)°, Z = 4 for CsFe(SO₄)(C₂O₄)_0.5 · H₂O. All compounds exhibit three‐dimensional frameworks composed of MO₆] octahedra, SO₄]^2– tetrahedra, and C₂O₄]^2– anions. The alkali cations are located in one‐dimensional tunnels.