功能化三联吡啶衍生物的合成及其对Fe~(2+)识别研究

设计合成了一种功能化三联吡啶衍生物(L),采用红外、核磁、质谱对其结构进行了表征。L具有聚集诱导发射增强性质。在Et OH-H2O介质中,L与Fe2+结合后显红色,且不受其他离子影响,是一种具有高度选择性和灵敏性的Fe2+比色识别探针。Fe2+紫外滴定实验表明,在557 nm处产生一个由金属-配体电荷转移引起的特征吸收峰,检测限为0.24μmol·L-1,可以实现对Fe2+的痕量检测。Job′s plot曲线得到L与Fe2+的结合比为2∶1。识别性能不受p H影响,且基于L的试纸可对水中Fe2+作出快速简便的识别,有一定的实际应用价值。     

A reversible fluorescent chemosensor for Fe~(3+) and H_2PO_4~- with “on-off-on” switching in aqueous media

To realize highly selective relay recognition of Fe3+ and H2PO4- ions, a simple benzimidazole-based fluorescent chemosensor(L) was designed and synthesized. Sensor L displays rapid, highly selective, and sensitive recognition to Fe3+ in H2O/DMSO(1:1, v/v) solutions. The in situ-generated L-Fe3+ complex solution exhibits a fast response and high selectivity toward dihydrogen phosphate anion via the Fe3+ displacement approach. The detection limits of sensor L to Fe3+ and L-Fe3+complex to H2PO4- anion were estimated to be 1.0 × 10-9 mol/L. Notably, the sensor was retrievable to indicate dihydrogen phosphate anions with Fe3+, and H2PO4-, in turn, increased. This successive recognition feature of sensor L makes it a potential utility for Fe3+ and H2PO4- anion detection in aqueous media.     

Fe~(2+)/H_2O_2对脲醛树脂胶ζ电位及其稳定性的影响

采用胶体化学的方法对Fe2+/H2O2影响脲醛树脂(UF)胶ζ电位及其稳定性的因素进行了研究。结果表明,在pH=8.0时,脲醛树脂胶粒的ζ电位平均值约-32.5mV,粒子带负电,并以单分散形式存在。随着Fe2+离子或H2O2加入量的增加,脲醛树脂胶ζ电位的绝对值迅速减小,从而使胶粒间排斥势垒降低,胶粒发生聚集,体系粘度随之增大并最终产生凝胶。其中,Fe2+离子对脲醛树脂胶粒的ζ电位和粘度η变化的影响幅度比H2O2更为明显。pH值对胶体稳定性的影响主要表现在,pH值约为9时,体系具有最大的ζ电位,除此之外,pH值增大或减小ζ电位的绝对值均迅速减小,其中pH9时ζ电位的绝对值下降幅度更为明显。采用胶体的双电层理论对Fe2+/H2O2影响脲醛树脂胶稳定性的机理进行了探讨。     

Fe~(3+)离子对二氧化钛光电化学催化性能的影响

应用电化学阳极氧化法制备Ti上多孔状纳米晶TiO2薄膜,以及不同Fe3+离子掺杂量的二氧化钛薄膜.研究了Fe3+离子掺杂对二氧化钛薄膜吸收光谱和光催化活性的影响,发现Fe3+的掺杂使薄膜的吸收带边发生红移,在可见光照射下其光催化活性也有一定的提高.     

无机阴离子、异丙醇及TiO_2对Fe~(3+)诱导全氟辛酸光化学降解影响的研究

254nm紫外光辐照下,溶解性Fe3+的存在有效促进了全氟辛酸(PFOA)的光化学降解.Fe3+浓度为30μmol·L-1时,Fe2(SO4)3,FeCl3和Fe(NO3)3三种溶解性铁盐对PFOA的降解和脱氟没有显著的差别.过量的SO24-与Fe3+具有较强的形成配合物的能力,由软件Visual MINTEQ2.52计算得出,Fe3+与过量的SO42-形成Fe(SO4)+和Fe(SO4)-2两种形态的配合物,其分配比的总和占16.32%,从而减少了PFOA与铁离子形成配合物的机会,进而抑制了其有效的光化学降解;过量的Cl-与Fe3+形成一配位的FeCl2+,其生成量仅占所有铁物种形态总和的0.12%,对PFOA的降解没有明显的影响,理论计算与实验结果相一致.羟基自由基捕获剂-异丙醇的加入未抑制PFOA的降解,二氧化钛的存在亦未促进其降解,进一步表明Fe3+诱导PFOA的光化学降解不是羟基自由基直接作用的结果.     

电泳中介微分析法测定铁(Ⅱ)和铜(Ⅱ)

利用电泳中介微分析通过与邻菲罗啉的络合反应完成了对Fe2+与Cu2+的同时测定。在压差作用下,淌度较小的邻菲罗啉在金属离子区带之前首先进样,加高电压后,两区带电泳在磷酸缓冲液中 (pH=4. 5)混合、反应形成络合物并实现电泳分离。研究了缓冲液pH、试剂和样品区带长度对分离效果的影响。对于Fe2+与Cu2+两离子,方法的检出限(S/N=3)分别为 1. 6和 11μmol/L;线性范围分别为 5. 0×10-6 ~3. 0×10-4 mol/L(r=0. 9979)和 8. 0×10-5 ~3. 0×10-4 mol/L(r=0. 9996)。采用标准矿样验证了测定Fe2+的可行性。     

一种基于共振瑞利散射和荧光增强并对Fe~(3+)和Fe~(2+)具有高识别作用的荧光方法的研究

本文合成了4-甲基哌嗪-1,8-萘酰亚胺修饰的β-环糊精,该化合物对Fe3+和Fe2+展现出良好的选择性识别能力。当适量的氨水加入到该化合物水溶液中后,溶液体系的荧光被完全猝灭。然而,当Fe3+和Fe2+加入到该溶液体系后,520nm处的荧光信号和416nm处的共振瑞利散射峰均逐渐增强。Fe3+和Fe2+引起的荧光强度和共振瑞利散射强度比值的差异可用于鉴别Fe3+和Fe2+,同时,该方法还展现了较高的灵敏度。本文建立的方法对Fe3+检测的线性范围为1.5×10-5~2.2×10-5mol/L,检测限为1.1×10-5mol/L;对Fe2+检测的线性范围为0.5×10-5~4.2×10-5mol/L,检测限为0.6×10-5mol/L。     

新型二维草酸根桥联配合物 {[Cu(en)~2]~4[KFe(C~2O~4)~3]~4}~n的合成、结构 和磁性

合成了一个新型草酸根桥联的二维配合物{[Cu(en)2]4[KFe(C2O4)3]4}n,并进行了晶体结构测试和磁性研究.晶体结构分析显示:K+离子为罕见的八配位环境,2个C2O42-和2个或1个K+离子长程桥联2个FeⅢ离子,形成一个二维网状的[KFe(C2O4)3]n2n-骨架,[Cu(en)2]2+单元通过(en)N-H…O(C2O4)氢键与[KFe(C2O4)3]n2n-骨架连接.变温磁化率测量表明:FeⅢ与FeⅢ间存在着弱的磁相互作用,J=-0.17cm-1.     

可见光下Fe~（3＋）掺杂对K2La2Ti3O（10）分解水制氢性能的影响

采用溶胶-凝胶法制备了Fe3+掺杂的Fe-K2La2Ti3O10.光催化剂,并通过X射线衍射(XRD)、紫外-可见漫反射(DRS)、X射线光电子能谱(XPS)等技术对其进行了表征和分析,考察了不同掺杂量对K2La2Ti3O10的性质及光催化分解水制氢活性的影响.结果表明,Fe-K2La2Ti3O10.在400-650 nm范围内显示强吸收,光谱响应扩展到可见光区(λ>400 nm),掺杂Fe3+后,K2La2Ti3O10.的可见光区的光催化制氢活性显著提高,掺杂量为nPe/nn=0.04时活性最佳,当催化剂用量为0.1 g,反应液为CH3OH(30 mL)+H2O(90 mL)时,产氢量达到1.92 μmol·h-1,为未掺杂时的4倍.     

一种新型氧化还原电解液电化学电容器体系

以含有Fe3+/Fe2+离子对的H2SO4溶液为电解液, 以多孔炭做电极材料, 就Fe3+/Fe2+离子对在多孔炭纳米孔隙中的电化学行为及准电容效应进行了探讨. 循环伏安测试结果表明, Fe3+/Fe2+离子对在多孔炭电极纳米孔隙中发生了可逆的电化学反应. 恒流充放电结果发现, 加入Fe3+/Fe2+使得充放曲线出现对称的充放电平台, 有效地提高了电化学电容器(EC)的电能存储容量, 其单电极比电容最高达174 mAh•g−1, 比单纯的H2SO4电解液的比电容高109 mAh•g−1, 且有着良好的循环稳定性. 根据实验现象及结果, 探讨了Fe3+/Fe2+离子对在EC电极上的充放电机理, 并提出了一种新的概念——氧化还原电解液电化学电容器.     

Model Compounds for Iron Proteins. Structures and Magnetic, Spectroscopic, and Redox Properties of Fe(III)M(II) and [Co(III)Fe(III)](2)O Complexes with (&mgr;-Carboxylato)bis(&mgr;-phenoxo)dimetalate and (&mgr;-Oxo)diiron(III) Cores

A series of heterobimetallic complexes of the type [Fe(III)M(II)L(&mgr;-OAc)(OAc)(H(2)O)](ClO(4)).nH(2)O (2-5) and [{Fe(III)Co(III)L(&mgr;-OAc)(OAc)}(2)(&mgr;-O)](ClO(4))(2).3H(2)O (6) where H(2)L is a tetraaminodiphenol macrocyclic ligand and M(II) = Zn(2), Ni(3), Co(4), and Mn(5) have been synthesized and characterized. The (1)H NMR spectrum of 6 exhibits all the resonances between 1 and 12 ppm. The IR and UV-vis spectra of 2-5 indicate that in all the cases the metal ions have similar coordination environments. A disordered crystal structure determined for 3 reveals the presence of a (&mgr;-acetate)bis(&mgr;-phenoxide)-Ni(II)Fe(III) core, in which the two metal ions have 6-fold coordination geometry and each have two amino nitrogens and two phenolate oxygens as the in-plane donors; aside from the axial bridging acetate, the sixth coordination site of nickel(II) is occupied by the unidentate acetate and that of iron(III) by a water molecule. The crystal structure determination of 6 shows that the two heterobinuclear Co(III)Fe(III) units are bound by an Fe-O-Fe linkage. 6 crystallizes in the orthorhombic space group Ibca with a = 17.577(4) ?, b = 27.282(7) ?, c = 28.647(6) ?, and Z = 8. The two iron(III) centers in 6 are strongly antiferromagnetically coupled, J = -100 cm(-1) (H = -2JS(1).S(2)), whereas the other two S(1) = S(2) = (5)/(2) systems, viz. [Fe(2)(III)(HL)(2)(&mgr;-OH)(2)](ClO(4))(2) (1) and the Fe(III)Mn(II) complex (5), exhibit weak antiferromagnetic exchange coupling with J = -4.5 cm(-1) (1) and -1.8 cm(-1) (5). The Fe(III)Ni(II) (3) and Fe(III)Co(II) (4) systems, however, exhibit weak ferromagnetic behavior with J = 1.7 cm(-1) (3) and 4.2 cm(-1) (4). The iron(III) center in 2-5 exhibits quasi-reversible redox behavior between -0.44 and -0.48 V vs Ag/AgCl associated with reduction to iron(II). The oxidation of cobalt(II) in 4 occurs quasi-reversibly at 0.74 V, while both nickel(II) and manganese(II) in 3 and 5 undergo irreversible oxidation at 0.85 V. The electrochemical reduction of 6 leads to the generation of 4.     

Iron(III) activation hits a [4 + 4] macrocycle

The tetranuclear complex [Fe(III)2(L')(OH)(CH3O)]2, 1, has been synthesised from the reaction of either ferrous [in excess as 4:1 or stoichiometric 2:1 iron(II) : H4L] or ferric ions [4:1 iron(III) : H4L] with the large macrocycle, H4L, using aerobic conditions in methanol in the presence of triethylamine. The structure of 1 was determined by single-crystal X-ray diffraction. These reaction conditions lead to the modification of the original macrocycle through the incorporation of a methylene group between two amine groups to give an imidazolidine ring in (L')4-. The controlled addition of formaldehyde into the reaction system results in a significantly improved yield of 1, suggesting that it is involved in the reaction mechanism. The (L')4- macrocycle binds to two, well-separated, iron(III) centres [Fe(1)...Fe(1a) > 8 A]. Each iron(III) centre is further linked via hydroxy and methoxy bridges to equivalent iron(iii) centres contained in a second macrocycle. Overall this gives a structure containing two {Fe(OH)(CH(3)O)Fe} dimers [Fe(1)...Fe(2)ca. 3.2 A] sandwiched by two (L')4- macrocycles. The complex was further characterised by SQUID magnetic measurements and can be interpreted in terms of two isolated antiferromagnetically coupled Fe(III) dimers (J=-23.75 K).     

Selective extraction of iron(III) from aqueous nitrate solution in the presence of cobalt(II), copper(II) and nickel(II) ions using bis(delta2-2-imidazolinyl)-5,5'-dioxime.

The feasibility of using bis(delta2-2-imidazolinyl)-5,5'-dioxime (H2L) for the selective extraction of iron(III) from aqueous solutions was investigated by employing an solvent-extraction technique. The extraction of iron(III) from an aqueous nitrate solution in the presence of metal ions, such as cobalt(II), copper(II) and nickel(II), was carried out using H2L in binary and multicomponent mixtures. Iron(III) extraction has been studied as a function of the pH, equilibrium time and extractant concentration. From the extracted complex species in the organic phase, iron(III) was stripped with 2 M HNO3, and later determined using atomic-absorption spectrometry. The extraction was found to significantly depend on the aqueous solution pH. The extraction of iron(III) with H2L increases with the pH value, reaching a maximum in the zone of pH 2.0, remaining constant between 2 and 3.5 and subsequently decreasing. The quantitative extraction of iron(III) with 5 x 10(-30 M H2L in toluene is observed at pH 2.0. H2L was found to react with iron(III) to form ligand complex having a composition of 1:2 (Fe:H2L).     

Unravelling the intrinsic features of NO binding to iron(II)- and iron(III)-hemes

Electrospray ionization of appropriate precursors is used to deliver [Fe (III)-heme] (+) and [Fe (II)-hemeH] (+) ions as naked species in the gas phase where their ion chemistry has been examined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. In the naked, four-coordinate [Fe (II)-hemeH] (+) and [Fe (III)-heme] (+) ions, the intrinsic reactivity of iron(II)- and iron(III)-hemes is revealed free from any influence due to axial ligand, counterion, or solvent effects. Ligand (L) addition and ligand transfer equilibria with a series of selected neutrals are attained when [Fe (II)-hemeH] (+), corresponding to protonated Fe (II)-heme, is allowed to react in the FT-ICR cell. A Heme Cation Basicity (HCB) ladder for the various ligands toward [Fe (II)-hemeH] (+), corresponding to -Delta G degrees for the process [Fe (II)-hemeH] (+) + L --> [Fe (II)-hemeH(L)] (+) and named HCB (II), can thus be established. The so-obtained HCB (II) values are compared with the corresponding HCB (III) values for [Fe (III)-heme] (+). In spite of pronounced differences displayed by various ligands, NO shows a quite similar HCB of about 67 kJ mol (-1) at 300 K toward both ions, estimated to correspond to a binding energy of 124 kJ mol (-1). Density Functional Theory (DFT) computations confirm the experimental results, yielding very similar values of NO binding energies to [Fe (II)-hemeH] (+) and [Fe (III)-heme] (+), equal to 140 and 144 kJ mol (-1), respectively. The kinetic study of the NO association reaction supports the equilibrium HCB data and reveals that the two species share very close rate constant values both for the forward and for the reverse reaction. These gas phase results diverge markedly from the kinetics and thermodynamic behavior of NO binding to iron(II)- and iron(III)-heme proteins and model complexes in solution. The requisite of either a very labile or a vacant coordination site on iron for a facile addition of NO to occur, suggested to explain the bias for typically five-coordinate iron(II) species in solution, is fully supported by the present work.     

Spectrophotometric studies on ion-pair extraction equilibria of the iron(ii) and iron(III) complexes with 4-(2-pyridylazo)resorcinol

The ion-pair extraction equilibria of the iron(II) and iron(III) chelates of 4-(2-pyridylazo)resorcinol (PAR, H(2)L) are described. The anionic chelates were extracted into chloroform with benzyldimethyltetradecylammonium chloride (QC1) as counter-ion. The extraction constants were estimated to be K(ex1)(Fe(II)) = [Q{Fe(II)(HL)L}](0)/[Q(+)][{Fe(II)(HL)L}(-)] = 10(8.59 +/- 0.11), K(ex2)(Fe(II)) = [Q(2){Fe(II)L(2)}](o)/ [Q(+)](2)[{Fe(II)L(2)}(2-)] = 10(12.17 +/- 0.10) and K(ex1)(Fe(III)) = [Q{Fe((III))L(2)}](o)/(Q(+)][{Fe(III)L(2)}(-)] = 10(6.78 +/- 0.15) at I = 0.10 and 20 degrees , where [ ](o) is concentration in the chloroform phase. Aggregation of Q{Fe(III)L(2)} in chloroform was observed and the dimerization constant (K(d) = [Q(2){Fe(III)L(2)}(2)](o)/[Q{Fe(III)L(2)}](o)(2)) was evaluated as log K(d) = 4.3 +/- 0.3 at 20 degrees . The neutral chelates of {Fe(II)(HL)(2)} and {Fe(III)(HL)L}, and the ion-pair of the cationic chelate, {Fe(III)(HL)(2)}ClO(4), were also extracted into chloroform or nitrobenzene. The relationship between the forms and extraction properties of the iron(II) and iron(III) PAR chelates are discussed in connection with those of the nickel(II) and cobalt(III) complexes. Correlation between the extraction equilibrium data and the elution behaviour of some PAR chelates in ion-pair reversed-phase partition chromatography is also discussed.     

Polymer Supported Schiff Base Complexes of Iron(III), Cobalt(II) and Nickel(II) Ions and their Catalytic Activity in Oxidation of Phenol and Cyclohexene

The polymer supported transition metal complexes of N,N′‐bis (o‐hydroxy acetophenone) hydrazine (HPHZ) Schiff base were prepared by immobilization of N,N′‐bis(4‐amino‐o‐hydroxyacetophenone)hydrazine (AHPHZ) Schiff base on chloromethylated polystyrene beads of a constant degree of crosslinking and then loading iron(III), cobalt(II) and nickel(II) ions in methanol. The complexation of polymer anchored HPHZ Schiff base with iron(III), cobalt(II) and nickel(II) ions was 83.30%, 84.20% and 87.80%, respectively, whereas with unsupported HPHZ Schiff base, the complexation of these metal ions was 80.3%, 79.90% and 85.63%. The unsupported and polymer supported metal complexes were characterized for their structures using I.R, UV and elemental analysis. The iron(III) complexes of HPHZ Schiff base were octahedral in geometry, whereas cobalt(II) and nickel(II) complexes showed square planar structures as supported by UV and magnetic measurements. The thermogravimetric analysis (TGA) of HPHZ Schiff base and its metal complexes was used to analyze the variation in thermal stability of HPHZ Schiff base on complexation with metal ions. The HPHZ Schiff base showed a weight loss of 58% at 500°C, but its iron(III), cobalt(II) and nickel(II) ions complexes have shown a weight loss of 30%, 52% and 45% at same temperature. The catalytic activity of metal complexes was tested by studying the oxidation of phenol and epoxidation of cyclohexene in presence of hydrogen peroxide as an oxidant. The supported HPHZ Schiff base complexes of iron(III) ions showed 64.0% conversion for phenol and 81.3% conversion for cyclohexene at a molar ratio of 1∶1∶1 of substrate to catalyst and hydrogen peroxide, but unsupported complexes of iron(III) ions showed 55.5% conversion for phenol and 66.4% conversion for cyclohexene at 1∶1∶1 molar ratio of substrate to catalyst and hydrogen peroxide. The product selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was 90.5% and 96.5% with supported HPHZ Schiff base complexes of iron(III) ions, but was found to be low with cobalt(II) and nickel(II) ions complexes of Schiff base. The selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was different with studied metal ions and varied with molar ratio of metal ions in the reaction mixture. The selectivity was constant on varying the molar ratio of hydrogen peroxide and substrate. The energy of activation for epoxidation of cyclohexene and phenol conversion in presence of polymer supported HPHZ Schiff base complexes of iron(III) ions was 8.9 kJ mol^?1 and 22.8 kJ mol^?1, respectively, but was high with Schiff base complexes of cobalt(II) and nickel(II) ions and with unsupported Schiff base complexes.     

Iron(II) complexes with tetradentate bis(aminophenolate) ligands: synthesis and characterization, solution behavior, and reactivity with O(2)

Tetradentate bis(aminophenolate) ligands H(2)salan(X) and H(2)bapen(X) (where X refers to the para-phenolate substituent = H, Me, F, Cl) react with [Fe{N(SiMe(3))(2)}(2)] to form iron(II) complexes, which in the presence of suitable donor ligands L (L = pyridine or THF) can be isolated as the complexes [Fe(salan(X))(L)(2)] and [Fe(bapen(X))(L)(2)]. In the absence of donor ligands, either mononuclear complexes, for example, [Fe(salan(tBu,tBu))], or dinuclear complexes of the type [Fe(salan(X))](2) are obtained. The dynamic coordination behavior in solution of the complexes [Fe(salan(F))(L)(2)] and [Fe(bapen(F))(L)(2)] has been investigated by VT (1)H and (19)F NMR spectroscopy, which has revealed equilibria between isomers with different ligand coordination topologies cis-α, cis-β and trans. Exposure of the iron(II) salan(X) complexes to O(2) results in the formation of oxo-bridged iron(III) complexes of the type [{Fe(salan(X))}(2)(μ-O)] or [{Fe(salan(X))(L)}(2)(μ-O)]. The lack of catalytic activity of the iron(II) salan and bapen complexes in the oxidation of cyclohexane with H(2)O(2) as the oxidant is attributed to the rapid formation of stable and catalytically inactive oxo-bridged iron(III) complexes.     

Iron (III) Ion Selective Electrode Based on Dithia 12-Crown-4

An iron (III) ion selective PVC membrane electrode based on 1,7-dithia 12-crown-4 as a neutral carrier was prepared. Monovalent responses with a Nerstian slope of 56+1 mV/decade was observed for the Fe (III) ion-selective electrode within the concentration range 10^?3–10^?5 M Fe (NO₃)₃. The monovalent responses may be attributed to the formation of Fe (OH)₂⁺ or Fe (OH)₂(H₂O)⁺₄ species in aqueous solutions and the absorption of these ions into the PVC electrode membrane. The electrode exhibited good selectivity for Fe (III) in comparison with various alkali, alkali-earth and some heavy metal ions. The effects of the composition of the membrame, addition of STPB (sodium tetraphenyl borate), the concentration of internal solution of the electrode and anions in the test solutions were discussed.     

Electrochemical Behavior of Iron(III)/Iron(II) Couple in Dimethylformamide

The electrochemical behavior of the iron(III)/iron(II) couple was investigated in both complexing (Cl⁻) and noncomplexing (ClO⁻₄) media in dimethylformamide (DMF), and the results were compared with the results obtained in aqueous solutions. The diffusion coefficients for iron(III) and iron(II) in DMF are larger in complexing medium than in noncomplexing medium, contrary to the results obtained in aqueous solutions. The heterogeneous electron transfer rate constants for the iron(III)/iron(II) couple obtained in DMF were found to be smaller in DMF solution as a result of the specific adsorption of DMF. The formal potential of the Fe(III)/Fe(II) couple in DMF is about 0.2 V less positive in noncomplexing medium as a result of the greater stabilization of iron(III) by the strongly cation-solvating DMF. The formal potential of the same couple in complexing medium (Cl⁻) was found to be 0.5 V less positive due to a combination of solvation and complexation effects. Cyclic voltammetric investigations show a quasi-reversible electron transfer without any coupled chemical reaction.     

Redox properties of NN′-X-phenylenebis(Y-salicyli-deneiminato)iron(II) complexes and reactivity of the corresponding iron(III) complexes towards catecholates

The electrochemical behaviour of a series of iron(II) complexes with the tetradentate ligand NN′-1,2-phenylenebis(salicylideneimine), [Fe(II)L], was studied in non-aqueous solvents. The redox properties of the complexes were related to the nature of the substituents in the aromatic rings. Attention was devoted to dioxygen reactivity of the complexes. The electrode activity of the catechol—[NN′-1,2-phenylenebis(salicylidene-iminato) iron(III)] system, [Fe(III)L(catH)], was also studied; the results gave evidence that both the electrochemical oxidation and the chemical oxidation by dioxygen of [Fe(II)L] in the presence of catechol lead to the complex [Fe(III)L(catH)].