CRYSTAL-STRUCTURE AND HALOGEN NQR OF DIAMMONIUMALKANE HALIDES

The crystal structures of the isomorphous compounds 1,3-diammoniumpropyl dibromide and diiodide are reported. The structure was found to be: monoclinic, C-2h(4) - P2/n, Z = 4. The lattice constants of [H3N(CH2)(3)NH3](2+).2Br(-) are a = 1343.8 pm, b = 457.9 pm, c = 1347.1 pm and beta = 109.14 degrees; those for [H3N(CH2)(3)NH3](2+).2I(-) are a = 1421.3 pm, b = 478.0 pm, c = 1419.6 pm and beta = 110.10 degrees. The diammoniumpropyl cations are centrosymmetric and there are two formula units in the asymmetric unit. Hydro en bonds N-H...X(-) (X = Br or I) were observed. The discrepancy in the Br-79 and I-127 NQR spectra which showed no isomorphism, is removed by reinvestigation of the Br-79,Br-81 NQR spectra. At 77 K, upsilon(1) (Br-79) = 24.432 MHz and upsilon(2) (Br-79) = 14.042 MHz. The structures and the NQR spectra are compared and discussed.