SYNTHESIS AND PROPERTIES OF IRON(II) AND IRON(III) COMPLEXES WITH PROPYLIDENE-HYDRAZINO)-5,6-DIPHENYL-1,2,4-TRIAZINE (DCPT)

Proton-ligand formation constants of DCPT and metal-ligand formation c onstants of its complexes with Fe(II) and Fe(III) have been determined potentiometrically at 10, 20, 30, and 40 degrees C in 75% (v/v) dioxa ne-water at 0.10 M ionic strength (KNO3,). The thermodynamic parameter s Delta G, Delta H, and Delta S have also been evaluated. The possibil ity of forming M(HL), M(HL)(2), and M(HL)(3) species was substantiated from potentiometric and electronic absorption measurements. The value s of the stability constants logK(M)(HL), logK(M)(HL)(2), and logK(M)( HL)(3) derived from the spectrophotometric method are in good agreemen t with those obtained from potentiometric data. The use of DCPT as an analytical reagent for the spectrophotometric determination of iron is discussed. The solid complexes have been characterized by chemical an alysis and magnetic susceptibility, IR, NMR, and electronic spectral d ata.