The crystal structure of n-phenyl-2,4,6-triphenyl perchlorate has been determined using the direct methods technique and refined to R, = 0.055 and R, = 0.056 for 1321 unique reflections measured

The crystal of ES-I belongs to the orthorhombic system, space group Pbca. Unit cell parameters were determinedbyleastsquaresmethodandfound to be:a = 16.256(8), b = 15.359(8),andc = 9.918(5)A. The structure was solved by direct methods using the program SHELX86. The refinement was carried out using isotropic thermal parameters then followed by several cycles of anisotropic least squares to a final value of Ro = 0.073 for 1226 observed reflections. The hydrogen atoms were located from a difference Fourier map. Torsion angles calculation showed that rings A and B are planar as expected. All the calculations were carried out on a PC-Computer at physics department, Tanta University.

The crystal and molecular structure of 3-Hydrazino-1-Hydrazinothiocarbonyl pyrazoline (TNT3), C 4 H 10 N 6 S has been determined with MoK α α diffractometer data by direct methods. The compound crystallized in the monoclinic space group P2 1 /c, with a = 6.925(1), b=13.675(3), c=8.190(2)Ǻ and β=108.14(3)º. The structure was refined by full matrix least squares methods to R=0.047 using 917 reflections. The pyrazoline ring was found to be planner and delocalized. The amino groups connected to N7 and to N9 is extended and trans.

Crystal Structure of 1-(2-Pyridylmethyl)-2,4,6-Triphenyl- Pyridinium PerchlorateThe crystals of 1-(2-pyridymethyl)-2,4,6-triphenylpyridinium perchlorate are monoclinic, space group P 2Jb. The unit cell parameters arc a = 18.941(5), b = 19.502(6), c = 15.135(5), y = 115.99'(2), Z = 8, do = 1.31(3), d, = 1.319g/cm3. The structure has been determined by direct methods and refined by block diagonal least squares to R, = 0.08 for 2520 reflections. The phenyl rings in both molecules (I) and (11) are planar. These rings are twisted with respect to the central pyridyl rings.

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