The synthesis and spectroscopic characterization of Ni(II) complexes of 1-substituted phenyl-3,5-diphenylformazans

Novel Ni(II) complexes of formazans containing –NO2, –COOH, –Cl, –Br, –CH3 groups in the o-, m-, p-positions of the 1-phenyl ring were synthesized. The dyes were characterized using elemental analysis, FTIR, 1H NMR, 13C NMR, UV–vis and GC–mass spectra. UV–vis spectra indicated that their λmax was shifted to an extent that depended upon the type and position of the substituent on the ring; a broad absorption band was observed at 426–446 nm in CH2Cl2 at 25 °C. A linear correlation was obtained between Hammett substituent coefficients and λmax values.