STRUCTURE OF 11,3-DIAMMONIUMPROPANE-BIS(DIHYDROGEN MONOPHOSPHATE)

1,3-Propanediammonium bis(dihydrogenmonophosphate), C3H12N2(2+).2H2PO4-, M(r)- 270.12, monoclinic, Cc, a = 18.543 (3), b = 4.561 (4), c = 15.342 (3) angstrom, beta = 129.14 (1)-degrees, V = 1006.5 (7) angstrom 3, Z = 4, D(m) = 1.729, D(x) = 1.782 Mg m-3, lambda(Ag K-alpha) = 0.56087 angstrom, mu = 2.356 mm-1, F(000) = 568. T = 298 K, final R = 0.027 for 3362 independent reflexions. The structure shows a layer arrangement parallel to the b axis: planes of [H2PO4]- tetrahedra alternate with planes of [(CH2)3(NH3)2]2- groups. [H2PO4]- tetrahedra are connected through OH-O hydrogen bonds so that infinite chains of composition [H2PO4]n(n-) are formed parallel to the b axis. The chains are themselves interconnected by means of weak N-H-O hydrogen bonds originating from the [(CH2)3(NH3)2]2+ dications, forming a three-dimensional network. The 1,3-propanediammonium group has a trans configuration with a non-crystallographic inversion centre.