Two new ammonium diphosphates:: crystal structure of Mn0.5NH4H2P2O7•H2O and MnNaNH4P2O7•3 H2O

Two new ammonium diphosphates, Mn0.5NH4H2P2O7 . H2O (1) and MnNaNH4P2O7.3 H2O (2), have been synthesized and investigated by single crystal X-ray diffraction. Compound (1) crystallizes in the triclinic space group P (1) over bar, and the unit cell dimensions are a = 7.0029(2) Angstrom, b = 7.4401(2) Angstrom, c = 7.8771(2) Angstrom, alpha = 80.444(1)degrees, beta = 71.359(1)degrees, gamma = 87.408(1)degrees, V = 383.48(2)Angstrom(3), Z=2; compound (2) crystallizes in the monoclinic space group Cc, with the following unit cell dimensions: a=10.1124(4) Angstrom, b = 16.4448(7) Angstrom, c = 5.6000(3) Angstrom, beta = 104.304(2)degrees, V = 902.39(7)Angstrom(3), Z = 4. Final residuals are: R - 0.0281 and w(R) = 0.0769, by using 2356 reflections with I > 2sigma(I), for (1); R = 0.0301 and w(R) = 0.0682, by using 2322 reflections with I > 2sigma(I), for (2). The crystal packing of Mn0.5NH4H2P2O7.H2O consists of layers parallel to ac plane formed by MnO6 regular octahedra, H2P2O7 double tetrahedra and ammonium cations. Strong hydrogen bonds embed the dihydrogendiphosphate groups in the framework. The crystal packing of MnNaNH4P2O7.3H(2)O is made up of layers Of P2O7 double tetrahedra, NaO7 monocapped octahedra and MnO6 regular octahedra down c. Water and ammonium cations molecules fill up the cavities between the above mentioned polyhedra. Strong hydrogen bonds complete the network.