Synthesis and IR and NMR spectroscopic studies of amino derivatives of oxo-, thio-, and selenopyrazole. Crystal and molecular structure of 1-phenyl-3-methyl-4-methylene-(N-8-aminoquinoline)-5-oxopyrazole

Three compounds of the pyrazole series-o-oxo, thio, and seleno derivatives- have been synthesized and characterized by IR and NMR spectroscopy. The cry stal structure of the oxo derivative is determined (Syntex P2(1) diffractom eter, MoKalpha radiation, graphite monochromator, theta/2 theta scan mode, 2 theta(max) = 57 degrees, direct method, anisotropic-isotropic (H) least-s quares refinement for 2015 reflections, R = 0.043, wR2 = 0.1084). The cryst als are monoclinic, a = 7.543(1) Angstrom, b = 7.850(2) Angstrom, c = 27.90 9(6) Angstrom, beta = 93.79(3)degrees, Z = 2, and space group P2(1)/c. It i s found that the o-hydroxyazomethine derivatives of the pyrazolone series e xist in the crystal as 4-aminomethylene-5-oxo tautomers. The proton is loca lized at the exocyclic N atom. It lies in the plane of the main molecular f ragment and participates in the intramolecular bifurcate N-H ... O(N) hydro gen bond, which closes the six-membered and five-membered II-rings, respect ively. (C) 2000 MAIK "Nauka/Interperiodica".