SYNTHESIS AND CHARACTERIZATION OF 3 NEW LAYERED PHOSPHATES, NA2MNP2O7, NACSMNP2O7, AND NACSMN0.35CU0.65P2O7

Three new layered phosphates were isolated by employing high-temperatu re, solid-state reactions. These compounds belong to the A(2)(I)B(II)P (2)O(7) family. Na2MnP2O7, 1, crystallizes in the triclinic space grou p <P(1)over bar> (No. 2) with a = 5.316(2) Angstrom, b = 6.580(2) Angs trom, c = 9.409(3) Angstrom, alpha = 109.65(3)degrees, beta = 95.25(3) degrees, gamma = 106.38(3)degrees, and Z = 2; NaCsMnP2O7, 2, crystalli zes in the orthorhombic space group Cmc2(1) (No. 36) with a = 5.332(2) Angstrom, b = 15.009(2) Angstrom, c = 9.808(2) Angstrom, and Z = 4; N aCsMn0.35Cs0.65P2O7, 3, also crystallizes in the orthorhombic space gr oup Cmc2(1) (No. 36) with a = 5.208(2) Angstrom, b = 15.073(5) Angstro m, c = 9.708(3) Angstrom, and Z = 4. 1 possesses a new structure type composed of slabs of fused Mn4P4O26 cages, and 2 and 3 are isostructur al with K2CuP2O7. The unique cage structure found in 1 is made of two edge-sharing Mn2O10 dimers and two P2O7 pyrophosphate groups. These un its, arranged in parallel with respect to Mn-Mn and P-P vectors, are l inked in an alternating fashion through corner-sharing oxygen atoms. I ncorporation of larger Cs+ cations leads to a different structure in 2 and 3, while substituting similarly sized Cu2+ for Mn2+ cations in 3 does not alter the structure type. Magnetic susceptibility measurement s as well as bond valence sum calculations confirm the valence states of cations, including the high-spin, d(5) Mn2+ cation. UV-vis and IR s pectra of 1 and 2 are presented. In this report, the discrete nature o f the manganese oxide lattices is discussed.