New ternary complexes of Mn(II) with py, bipy, and terpy as primary ligand (L1) and 20,40,50,70-tetraiodofluorescein (I4FlCOOH) as secondary ligand (L2) were prepared. The stoichiometry for these complexes was found to be Mn(II):L1:L2 = 1:2:1, and the complex formula proposed is [Mn(L1)2(I4FlCOO)]?. The effect of substituent groups of L2 and the nitrogen atoms of L1 on
complex formation with Mn(II) was studied. Moreover, the interference of some cations and anions in the determination of Mn(II) by this method was investigated and the interferences of Cu(II) and Fe(III) with Mn(II) in their corresponding alloys were considered. A simple, rapid, and sensitive spectrophotometric method for determination of Mn(II) in its salts and Mn in its alloys is suggested.