Isolation and crystal structure of trans-2,2′,4,4′-tetramethyl-6,6′-dinitro azobenzene

Trans-2,2',4,4'-tetramethyl-6,6'-dinitro azobenzene (C16H16N4O4, M-r = 328.32) was isolated from benzene extract of the leaves of Aconitum sungpanense Hand. Mazz. as a new compound, and characterized by spectral methods and X-ray diffraction analysis. It crystallizes in monoclinic system, space group P2(1)/c with a = 8.544(l), b = 13.997(2), c = 7.161(1) Angstrom, beta = 112.97(1), V = 788.4(2) Angstrom(3), Z = 4 , D-c = 1.383 g/cm(3) , F(000) = 344 and mu(MoKalpha) = 0.102 mm(-1). The final R = 0.0395 and wR = 0.1140 for 1913 independent reflections with R-int = 0.0109 and 1329 observed reflections with I > 2sigma(I). The molecule is composed of two phenyl rings through trans N=N.