Structure and vibrational spectra of a new trihydrate diphosphate, MnNH4NaP2O7.3H2O

The new trihydrate diphosphate, MnNH(4)NaP(2)O(7)(.)3H(2)O, were synthesized and investigated by X-ray diffraction and vibrational spectroscopy. Single crystal structure has been obtained using 1361 reflections with a final R value of 0.0564. This salt crystallizes in the monoclinic system, space group Cc, with Z = 4 and the following unit-cell parameters: a = 10.1125(12), b = 16.4370(3), c = 5.5987(7) Angstrom, beta = 104.314degrees(9), V = 901.7 Angstrom(3). The atomic arrangement is a three-dimensional framework built from P2O74- diphosphate anions linked by MnO6, NaO6 and NH4O6 octahedra. The P2O74- anion shows bent eclipsed configuration with bridge angle P-O-P of 125.9(4)degrees. The infrared and Raman spectra of this salt have been recorded and interpreted using factor group analysis. Most of the bands are observed in both infrared and Raman spectra, which confirms a non-centrosymmetric space group. The apparence of upsilon(as) POP and upsilon(s) POP in infrared and Raman spectra point to a bent POP bridge in MnNH(4)NaP(2)O(7)(.)3H(2)O.