THE CRYSTAL-STRUCTURES OF 1,1'-DINITROBICYCLOPENTYL, 1,1'-DINITROBICYCLOHEXYL AND 1,1'-DINITROBICYCLOHEPTYL

The crystal and molecular structures of 1,1'-dinitrobicyclopentyl 1, 1,1'-dinitrobicyclohexyl 2 and 1,1'-dinitrobicycloheptyl 3 have been determined by X-ray diffraction methods. Compound 1 crystallizes in the monoclinic space group, C2/c, a = 16.247(2), b = 6.453 5(5), c = 11.161(2) angstrom, beta = 103.36(1) degree, Z = 4; compound 2 in the monoclinic space group, C2/c, a = 6.461(1), b = 11.012(2), c = 17.978(3) angstrom, beta = 90.73(1) degree, Z = 4; and compound 3 in the monoclinic space group, P21/n, a = 6.430 6(9), b = 11.544(2), c = 19.322(3) angstrom, beta = 90.12(1) degree, Z = 4. All three structures adopt gauche conformations with the nitro groups in close proximity. As the ring size increases the strain arising from contacts between the nitro groups increases and is reflected in increasing inter-ring and C-N bond lengths.