Molecules of C 1 2 H 4 F 8 N 2 crystallize in the orthorhombic space group P2 1 2 1 2 1 with cell constants a=9.200(1), b=10.896(1), c=23.178(3) 9 and V=2323.4(5) 9 3 . There are two molecules in the asymmetric unit which have D 2 symmetry. However these two molecules have C 2 symmetry in central C-C bonds, separately. Intramolecular steric repulsions between F atoms and N-H...F hydrogen bonds have very much affected the molecular conformation. The mean dihedral angle between intramolecular phenyl rings is 119.2(1) o . The N-C bonds have lengths 1.363(4)-1.407(4) 9 with a mean of 1.388 9. This is shorter than the conventional C-N (1.47(1) 9) bond length due to π-electron delocalizations (F.H. Allen, O. Kennard, D.G. Watson, L. Brammer, A.G. Orpen, R. Taylor, J. Chem. Soc. Perkin Trans. II (1987) S1-S19).The molecular structure of the title compound was also investigated by IR spectroscopy. It was shown that the IR spectra are in agreement with the crystal structure. On the other hand, theoretical and semi-emprical molecular mechanic calculations were carried out to obtain the most probable low-energy conformations by using MM3, PM3 and AM1 programs.