Kinetics and Mechanism of the Autocatalytic Oxidation of Bis(terpyridine)iron(II) by Peroxomonosulfate Ion (Oxone) in Acidic Medium

Abstract

The autocatalytic oxidation of the bis(terpyridine)iron(II) complex, Fe(tpy) by peroxomonosulfate ion (PMS) proceeds via the formation of the corresponding iron(III) complex (Fe(tpy)) as the primary oxidation product. The proton-assisted dissociation of Fe(tpy) and subsequent oxidation of Fe are side reactions in this system. In the initial stage of the reaction, a 1:1 adduct is formed between PMS and bis(terpyridine)iron(II), which decomposes in an intramolecular electron transfer reaction step. The autocatalytic role of Fe(tpy) was also confirmed in the overall process. This effect is interpreted by considering the formation of an additional adduct between PMS and Fe(tpy). The decomposition of the adduct yields two strong oxidizing intermediates, an Fe(IV) species and SO, which consume the iron(II) complex in rapid reaction steps. A detailed kinetic model was postulated for the overall oxidation of Fe(tpy) by PMS. The equilibrium constants for the formation of the adducts between PMS and complexes Fe(tpy) and Fe(tpy) were estimated as 129 ± 18 M and 87 ± 10 M, respectively. In contrast to the closely related Fe(phen)-PMS reaction, the N-oxide derivative of the ligand (tpyO) does not have any kinetic role in the overall process because of the very slow formation of the N-oxide in the reaction.

Metal‐Terpyridine Complexes in Catalytic Application – A Spotlight on the Last Decade

“…The kinetics and the mechanism of the oxidation of Fe(II)‐tpy bis‐complexes by oxone were analyzed by Beller et al . ; these authors confirmed the formation of such Fe(IV) species in the rate‐determine step of the autocatalytic formation of Fe(III) ions and oxidized tpy ligands.…”

Ligational, DFT modeling and biological properties of some new metal complexes with 3‐(bromoacetyl)coumarin and 1,10‐phenanthroline

“…Numerous studies of mixedligand containing Phen with various ligands are reported in the literature. [9][10][11][12][13] Also, a lot of literature data revealed that elements of biological relevance, Co (II), Ni (II), Cu (II), and Zn (II) take part in diverse functions and structures within biological systems these elements, in combination with various ligands have demonstrated a great cytotoxic activity. [14][15][16][17] To continue the investigation in the field of mixed ligand metal complexes, [18][19][20] the present work is concerned with the preparation of some new Mn (II), Fe (II), Co (II), Ni (II), Cu (II) and Zn (II) complexes of BAC and Phen, the complexes were identified on the basis of the data obtained from different analytical and spectroscopic tools to throw some light on the bonds formed and on their structures, also, DFT calculation and biological activity of the mixed ligand complexes has been investigated.…”

Reversible Assembly of Microgels by Metallo‐Supramolecular Chemistry

“…Indeed, it is reported that iron(III)/ bis-terpyridine complexes are not kinetically stable and exhibit av ery high lability so that microgel aggregates disassembly can be expected. [14] 3p resents UV/Vis and DLS experiments performed on microgels aggregates samples prior and after addition of KPS.T he absorption band at 567 nm characteristic of the [Fe II Tpy 2 ] 2+ complex at the molecular scale disappears after adding the oxidant molecules (Figure 3a). Accordingly,atthe microgel scale,D LS measurements show that the microgel aggregates break into individual microgels (Figure 3b)a fter 3h (Supporting Information, Figure S11).…”