CRYSTAL-STRUCTURES OF 2 ALLOTROPIC FORMS OF NA2COP2O7

Na2CoP2O7 may be prepared in two allotropic forms: I, rose, M(r) = 278.85, triclinic, P1, a = 9.735(2), b = 10.940(3), c = 12.289(4) angstrom, alpha = 148.78, beta = 121.76(1), gamma = 68.38(2)-degrees, V = 566.8(2) angstrom 3, Z = 4, D(meas) = 3.28(5) g cm-3, D(calc) = 3.267 g cm-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 37.12 cm-1, F(000) = 540, T = 298 K, R = 5.4% for 2911 observed reflections; and II, blue, M(r) = 278.85, orthorhombic, P2(1)cn, a = 7.713(2) angstrom, b = 10.271(4), c = 15.378(6)-degrees, V = 1218.2(8) angstrom 3, Z = 8, D(meas) = 3.06(5) g cm-3, D(calc) = 3.040 g cm-1, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 34.55 cm-1, F(000) = 1080, T = 298 K, R = 9.9% for 1450 observed reflections. Cobalt displays octahedral coordination to six oxygen atoms in the rose form whereas the metal coordination is tetrahedral in the blue form.