Novel, 1:2 Ni(II) complexes of 1,3-substituted phenyl-5-phenylformazans were synthesized. The formazans contained -NO2, -Cl, -Br, -CH3 -OCH3 groups at the o-, m-, p-positions of the 1-phenyl ring and -NO2 and -OCH3 groups at the m- and p-positions of the 3-phenyl ring. Their structures were identified by elemental analyses, FTIR, H-1 NMR, C-13 NMR, UV-vis and GC-mass spectra. UV-vis spectra indicated that their A a was shifted to an extent that depended upon the type and position of the substituent on the ring. A linear correlation was obtained between Hammett substituent coefficients and lambda(max) values. (c) 2007 Elsevier Ltd. All rights reserved.