The interaction of (1,8)bis(2-hydroxybenzamido)3,6-diazaoctane (LH2) with iron(III) in acidic medium resulted in the formation of a mononuclear complex, Fe(LH3)4+ which further yielded, [Fe(LH2)]3+, [Fe(LH)]2+, and [FeL]+ due to protolytic equilibria. The formation of [Fe(LH3)]4+ was investigated under varying [H+]T (0.01–0.10 mol dm−3) and [Fe3+]T (1.00 × 10−3–1.70 × 10−2, [L]T = 1.0 × 10−4 mol dm−3) (I = 0.3 mol dm−3, 10% MeOH + H2O, 25.0 °C). The reaction was reversible and displayed monophasic kinetics; the dominant path involved Fe(OH)(OH2) 5 2+ and LH 4 2+ . The mechanism is essentially a dissociative interchange (I d) and the dissociation of the aqua ligand from the encounter complex, [Fe(OH2)5OH2+, H4L2+] is rate limiting. The ligand binds iron(III) in a bidentate ([Fe(H3L)]4+), tetradentate ([Fe(H2L)]3+), pentadentate ([Fe(HL)]2+) and hexadentate fashion ([FeL]+) under varying pH conditions. Iron(III) promoted deprotonation of the amide and phenol moieties and chelation driven deprotonation of the sec-NH 2 + of the trien spacer unit are in tune with the above proposition. The mixed ligand complexes, [FeIII(LH)(X)] (X = N 3 − , NCS−, ACO−) are also reversibly formed in solution thus indicating that there is a replaceable aqua ligand in the complex conforming to its octahedral coordination, [Fe(LH)(OH2)]2+, the bound ligand is protonated at the sec-NH site. Despite the multidentate nature of the ligand the FeIII complexes are prone to reduction by sulfur(IV) and ascorbic acid. The redox reactions of different iron(III) species, FeIII(LHi) which involved ternary complex formation with the reductants have been investigated kinetically as a function of pH, [SIV]T and [ascorbic acid]T. The substantial pK perturbation of the bound ascorbate in [Fe(LH)(HAsc/Asc)]+/0 (ΔpK {[Fe(LH)(HAsc)] − HAsc − } > 6) is considered to be compelling evidence for chelation of HAsc−/Asc2− leading to hepta coordination of iron(III) in the ascorbate complexes. A novel binuclear complex with composition, [FeIII 2C20N4H35O11 (NO3)] has been synthesized and characterized by i.r., u.v.–vis, e.s.r., e.s.i.-Mass, 57Fe Mossbauer spectroscopy and magnetic moment measurements. The complex was isolated as a mixture of two forms C 1 and C 2 with 75.3 and 24.7%, respectively as computed from Mossbauer data. The isomer shift (δ) (quadrupole splitting, ΔE Q) are 0.32 mm s−1 (0.75 mm s−1) and 0.19 mm s−1 (0.68 mm s−1) for C 1 and C 2, respectively. The variable temperature magnetic moment measurements (10–300 K) of the sample showed that C 1 is an oxo dimer exhibiting antiferromagnetic interaction between the iron(III) atoms (S 1 = S 2 = 5/2, J = − 120 cm−1) while the dimer C 2 is a high spin species (S 1 = S 2 = 5/2) and exhibits normal paramagnetism obeying the Curie law. The cyclic voltametry response of the sample (DMF, [TEAP] = 0.1 mol dm−3) displayed quasi-reversible responses at − 0.577 V and − 1.451 V (versus SCE). This is in tune with the fact that the C 2 species reverts rapidly in solution to the relatively more stable oxo-bridged dimer (C 1) which is reduced in two sequential steps: C1 + e− → [FeL]+ + FeII; [FeL]+ + e− → FeIIL, the high labilility of the FeII complex is attributed to the irreversibility. The X-band e.s.r. spectrum of the polycrystalline sample at room temperature displayed a weak (unresolved) band at g = 4.2 and a strong band at g = 2.0 with hyperfine splitting due to the coordinated nitrogen (I = 1). At 77 K the band at g = 4.2 is intensified while that at g = 2 is broadened to the extent of near disappearance in agreement with the presence of the exchange coupled iron(III) centres.