Metal complex formazans. Part II. The reaction of copper salts with certain tetradentate formazans

1,5-Di-(2-hydroxyphenyl)- and 1-(2-hydroxyphenyl)-5-(2-carboxyphenyl)-3-substituted formazans react with both cupric acetate and cuprous chloride in methanol to give square planar copper(II) complexes. In contrast, under comparable conditions, 1,5-di-(2-carboxyphenyl)-3-substituted formazans give copper(II) complexes containing two molecules of water, which are probably octahedral. With cupric chloride in methanol two competing reactions occur, metal complex formation and oxidation of the formazan to tetrazolium salt. The relative importance of these reactions is governed by the substituents on the formazan.