MOLECULAR-STRUCTURE OF ISOPROPYL ENYL-4-PHENYLHYDRAZONO-5-OXO-3-PYRAZOLECARBOXYLATE

The new azopyrazolone dye has been synthesized and its crystal structu re has been investigated. Crystals of C19H18N4O3 are triclinic: P $$($ ) over bar 1, a = 7.484(1), b = 10.646(1), c = 11.897(1)Angstrom, alph a = 82.28(1), beta = 72.86(1), gamma = 86.83(1)degrees, Z = 2. The str ucture has been solved by direct methods and refined by full-matrix le ast-squares techniques to R = 0.050 for 2622 unique reflections. The t automeric form of the molecules has been determined as a hydrate form. Delocalization of the C5=O3 and C4=N3 pi-electrons and delocalization of the lone-pair electrons of N1, N3, and N4 atoms has been observed. The intramolecular N-H...O hydrogen bond forms the six-membered ring C2N2H...O condensed with the pyrazolone ring. The molecules are connec ted by intramolecular C-H...O hydrogen bonds.