The crystal and molecular structure of anhydrous diacetylhydrazine (–NHCOCH3)2
1960; Wiley; Volume: 13; Issue: 8 Linguagem: Inglês
10.1107/s0365110x60001461
ISSN1600-8642
Autores Tópico(s)Structural and Chemical Analysis of Organic and Inorganic Compounds
ResumoThe crystal of anhydrous diacetylhydrazine is of the symmetry D~-Ccma having four molecules in a unit cell with the dimensions a = 18-30, b = 6"51 and c = 4.79 A. The crystal and molecular structure have been determined to a high degree of accuracy by the three-dimensional Fourier and leastsquares methods.The positions of hydrogen atoms have also been determined.The molecule with a centre of symmetry is planar and lies in the (010) plane except two of the three hydrogen atoms in the methyl group.The N-N bond distance (1.396 /~) is slightly shorter than the average single bond distance and close to that of diformylhydrazine.The C-C bond (1.504 A) is slightly but significantly shorter than the normal C-C single bond, showing influence of the hyperconjugation.According to a nuclear magnetic resonance experiment, it is found that the methyl groups are rotating about the C-C axis at room temperature.The difference map shows, however, clearly the peaks of hydrogen atoms of the methyl group as well as of the amide group.The N-(2 and (2-0 bond lengths are 1.341 and 1.221 A, respectively.The molecules are linked by the N-H-.. O hydrogen bonds (2.877 /~) extended in the c-axis direction, forming molecular belts parallel to the (010) plane.As for the hydrogen bond, the angle N • • • O-C is 168.5 °.The thermal motion of the molecule may be described by the superposition of the libration about the centre of symmetry and the translational vibration, the ellipsoid of which has its principal axes in the directions of the crystallographic axes.The thermal expansion coefficients have also been measured between -150 and 30 °C. by the X-ray method, the average linear expansion coefficients being fla =4"9 × 10 -5, fib =2"0 × 10 -a, flc=3"5 × 10 -5 deg.-1.
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