New chromogens of the ferroin type-VI: some derivatives of 1- and 3-cyanoisoquinoline and substituted 2-cyanopyridines

The chromogenic reactions with iron(II), copper(I) and cobalt(II) of 32 recently synthesized pyridazines, triazines, tetrazines and certain other compounds containing the ferroin grouping have been examined spectrophotometrically. Some interesting examples were found of steric and donor-atom selectivities in chelation of iron by ligands containing several ferroin groups. Of the various chromogens studied, the pyridyl and isoquinolyl derivatives of phenyl or pyridyl substituted 1,2,4-triazine show the most promising analytical utility.