Synthesis and Characterization of Three New Layered Phosphates, Na2MnP2O7, NaCsMnP2O7, and NaCsMn0.35Cu0.65P2O7

Three new layered phosphates were isolated by employing high-temperature, solid-state reactions. These compounds belong to the AI2BIIP2O7 family. Na2MnP2O7, 1, crystallizes in the triclinic space group P1 (No. 2) with a = 5.316(2) A, b = 6.580(2) A, c = 9.409(3) A, α = 109.65(3)°, β = 95.25(3)°, γ = 106.38(3)°, and Z = 2; NaCsMnP2O7, 2, crystallizes in the orthorhombic space group Cmc21 (No. 36) with a = 5.332(2) A, b = 15.009(2) A, c = 9.808(2) A, and Z = 4; NaCsMn0.35Cs0.65P2O7, 3, also crystallizes in the orthorhombic space group Cmc21 (No. 36) with a = 5.208(2) A, b = 15.073(5) A, c = 9.708(3) A, and Z = 4. 1 possesses a new structure type composed of slabs of fused Mn4P4O26 cages, and 2 and 3 are isostructural with K2CuP2O7. The unique cage structure found in 1 is made of two edge-sharing Mn2O10 dimers and two P2O7 pyrophosphate groups. These units, arranged in parallel with respect to Mn−Mn and P−P vectors, are linked in an alternating fashion through corner-sharing oxygen atoms. Incorporation of l...