CRYSTAL-STRUCTURE AND IR AND RAMAN-SPECTRA OF THE BIS(ETHYLENEDIAMMONIUM) DIPHOSPHATE (NH3(CH2)2NH3)2.P2O7

Abstract: Classical methods extensively known for the synthesis of inorganic condensed phosphates are used to give compounds that are intermediate between inorganic and organic. We prepared the title compound to examine the possibility of using, in this new field, the ion exchange resin and Boulle ́'s methods. Chemical preparation, crystal structure, and vibrational studies are given for a new diphosphate. The bis(ethylenediammonium) diphosphate salt is monoclinic with the unit cell dimensions a = 8.724(1), b = 13.511(2), c = 10.039(1)Å, β = 96.25(1)°, V = 1176.3(5)Å3, Dm = 1.673Mg m-3, Dx = 1.684Mg m-3, μ = 2.163 mm-1, space group C2c with Z = 4. The structure was solved by the Patterson method and refined to a final R value of 0.059 for 2602 observed independent reflections. The P{single bond}O(L){single bond}P bridge is symmetrical with a P{single bond}O(L) distance of 1.570(1)Åand a POP angle of 141.94(7)°. The P2O4-7 anions are located around the twofold axis. The ethylenediammonium dications have a trans configuration. Half of them, having a crystallographic inversion center, are located in channels delimited by the diphosphate anions. The others, located around the twofold axis, are sandwiched along the c axis between two diphosphate anions. The cohesion and the stability of the atomic arrangement result from the N{single bond}H···O hydrogen bonds. The IR and Raman spectra of [NH3(CH)2NH32 · P2O7 are recorded and analyzed. From the spectra it is inferred that the P2O4-7 anion has a C2 symmetry in the crystal; all the POP modes (stretching and bending) are active in IR and Raman. © 1992 Academic Press, Inc. All rights reserved.