Compounds 1 (C17H22N2, M-r = 254.37) and 2 (C13H16N2, Mr = 200.28) have been synthesized and their crystal structures were determined by single-crystal X-ray diffraction. Crystal 1 belongs to triclinic, space group P (1) over bar with a = 6.524(2), b = 8.987(3), c = 12.746(5) angstrom, alpha= 95.220(7), beta = 90.055(6),. = 104.431(6)degrees, V = 720.5(4) angstrom(3), Z = 2, D-c = 1.173 g/cm(3), mu(MoK alpha) = 0.069 mm(-1), F(000) = 276, R = 0.0578 and wR = 0.1221 for 1487 observed reflections I > 2 sigma(I). Crystal 2 is of tetragonal system, space group I4(1)/a with a = 20.763(10), b = 20.763(10), c = 11.427(6) angstrom, V = 4926(4) angstrom(3), Z = 16, Dc = 1.080 g/cm(3), mu(MoKa) = 0.065 mm-1, F(000) = 1728, R = 0.0581 and wR = 0.1288 for 1408 observed reflections with I > 2 sigma(I). Although the two compounds are similar with the same pyrazole and benzene ring units, X-ray analysis reveals that their structures are completely different maybe caused by steric effects.