Abstract: The interaction of Cr(II) and Sr(II) with a series of four novel N-heterocycles viz. 2-(1,3-dioxisoindoline-2-yl)-N-(4-oxo-2-phenylquinozolin3(4H)-yl), 1-(2-((4-oxo-2-phenylquinozolin-3(4H)-yl) carbomoyl), diethyl 1-(2-(1,3-dioxoisoindolin-2-yl)-3-methylbutanoyl)-2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate, diethyl 1-(2-(1,3-dioxoisoindolin-2-yl)butanoyl)-2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate studied by spectrophotometric technique at 0.01 M ionic strength and 28°C in 70% dioxane-water mixture. The data obtained used to estimate the stability constant of the complexes. Investigation of Cr(II) and Sr(II) complexes with these ligands shows 1 : 1 complex formation. The values of conditional stability constants of Sr(II) complexes are greater than the corresponding Cr(II) complexes. The results obtained of stability constants are in good agreement with the structure of ligand and reactivity pattern of metal ion. These can be of interest for specialists in the field of coordination chemistry. [ABSTRACT FROM AUTHOR]