Iridium(III) Amine Complexes as High-Stability Structure-Directing Agents for the Synthesis of Metal Phosphates

Abstract

The metal complexes Ir(en)33+ and M((±)chxn)33+ (en = 1,2-diaminoethane, chxn = trans-1,2-diaminocyclohexane, M = Ir or Co) have been used to synthesize the layered compound Δ,Λ-Ir(en)3[Al3P4O16]·xH2O (x ≈ 3.45) and the chain compounds M(chxn)3[Al2P3O12]·xH2O (x ≈ 4). The chain compounds contain two of the eight possible isomeric forms of the cation, Λ(lel2ob)-[M(S,S-chxn)2(R,R-chxn)]3+ and its mirror image Δ(lel2ob)-[M(R,R-chxn)2(S,S-chxn)]3+. Microcrystals of the Ir(en)33+ and Ir(chxn)33+ containing AlPOs were structurally characterized using synchrotron radiation. Δ,Λ-Ir(en)3[Al3P4O16]·xH2O is isomorphous with the previously reported material Δ,Λ-Co(en)3[Al3P4O16]·xH2O. The materials prepared using Co((±)chxn)33+ and Ir((±)chxn)33+ are also isostructural with one another and contain a new type of aluminophosphate chain. The use of Ir(III) in the structure-directing metal complex enabled the use of much harsher hydrothermal conditions for the metal phosphate synthesis than could be employed with the corresponding Co(III) complexes. Ir(C2N2H8)3[Al3P4O16]·3.45H2O: Mr = 895.5, orthorhombic, Pnna, a = 8.548(5), b = 21.983(14), c = 13.970(9) Å, V = 2625(3) Å3, Z = 4, ρcalc = 2.266 g cm-3, λ = 1.1167 Å, μ = 14.03 mm-1, F(000) = 1762, T = 293 K, RF = 0.128 for 954 reflections I >2σ(I). Ir(C6N2H14)3Al2P3O12·4H2O: Mr = 945.7, triclinic, P1̄, a = 9.649(5), b = 12.365(9), c = 16.083(8) Å, α =100.02(6), β = 101.64(5), γ = 104.75(6)°, V = 1765(2) Å3, Z = 2, ρcalc = 1.779 g cm-3, λ = 1.1167 Å, μ = 9.747 mm-1, F(000) = 952, T = 293 K, RF = 0.128 for 966 reflections I > 2σ(I).