Formazan tetradentate ligand

The preparation of chromium(III) and cobalt(III) complexes of tetradentate formazans in which the coordination sphere of the metal is completed by a variety of neutral ligands has been reported116 and these (185) were claimed to be very stable towards acids. By analogy with copper complexes, however, some doubt must exist regarding the structures assigned to those complexes derived from l,5-bis(2-carboxyphenyl)formazans. Various dyestuff and pigment applications have... 

Metal Containing Tetradentate Formazans. Formazans with two complex-forming groups in the 2- and 2 -positions of the N1- and N5-aryl substituents are potential quadridentate ligands. They form 1 1 coordination complexes with four- and six-coordinate metals ... 

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