Synthesis, Spectroscopic, Spectrophotometric and Crystallographic Investigations of 4-{[(1E)-(3,4-dimethoxyphenyl)methylene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one and 4-{[(1E)-(2-hydroxy-5-methoxyphenyl)methylene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H- pyrazol-3-one

Two new Schiff base ligands 4-{[(1E)-(3,4-dimethoxyphenyl) methylene] amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (1) and 4-{[(1E)-(2-hydroxy-5-methoxyphenyl) methylene] amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (2) have been prepared and characterized using elemental analysis, UV-vis, FT-IR, (1)H and (13)C NMR spectroscopy, and X-ray crystallographic technique. Tautomeric equilibria (phenol-imine, O-H(center dot center dot center dot)N and keto-amine, O(center dot center dot center dot)H-N forms) have been studied by using UV-vis absorption spectra for the compound 2 in some solutions. Crystal structure analyses showed that the title molecules 1 and 2 crystallize in the monoclinic space group P2(1/c) and P2(1) with the unit cell parameters: a = 12.5665(3) angstrom and 5.6666(2) angstrom; b = 10.4791(2) angstrom and 12.2444(5) angstrom; c = 14.6240(3) angstrom and 12.1556(4) angstrom; V = 1820.65(7) angstrom(3) and 826.84(5) angstrom(3); D(x) = 1.282 g.cm(-3) and 1.355 g. cm(-3); and Z = 4 and 2, respectively.