Synthesis, crystal structures, and modifications of novel framework gallium diphosphonates

The framework gallium diphospohonates Ga2[O3PC 2H4PO3](H2O)2F 2·2H2O (1) (triclinic, P1, a = 5.0432(2) Å, b = 7.2468(3) Å, c = 8.3499(4) Å, α = 107.489(2)°, β = 92.444(2)°, γ = 109.338(2)°, Z = 1) and Ga2[O 3PCH2(C6H4)CH2PO 3](H2O)2F2 (2) (triclinic, P1, a = 4. 9673(1) Å, b = 7. 0898(2) Å, c = 10.1220(3) Å, α = 92.698(2)°, β = 93.153(2)°, γ = 109.122(2)°, Z = 1) and the solid-solution series Ga2{[O3PCH2(C 6H4)CH2PO3]1-x(HPO 3)2x}(H2O)2F2 (0 ≤ x ≤ 0.146) x = 0.541 (3) and x = 0.144 Ga2{[O3PCH 2(C6H4)CH2PO3] 0.853(6)(HPO3)0.29(1)}(H2O) 2F2 (4) (triclinic, P1, a = 4.959(2) Å, b = 7.078(2) Å, c = 10.024(3) Å, α = 92.404(5)°, β = 92.955(5)°, γ = 109.187(5)°, Z = 1) have been synthesized by solvothermal methods and their structures determined using X-ray diffraction data. All the materials contain linear chains of corner-sharing GaO 4F2 octahedra that are linked by the diphosphonate groups to form framework structures. The channels of 1 are found to contain two water molecules per unit cell while those in 2 are too narrow to contain extraframework species. The apertures created in the phosphite-substituted derivatives of 2 (3 and 4) are shown, by crystallographic methods, to be considerably larger than those in 2 and, by thermogravimetric methods, to create more open structures. The synthetic conditions or form of the diphosphonate group are found to play a defining role in the adoption of this particular configuration of the inorganic component in the reported compounds and provide an additional strategy for the rational design of framework hybrid organicinorganic solids.