H2L2 Ligands Research Articles

Unexpected structural complexity of d-block metallosupramolecular architectures within the benzimidazole-phenoxo ligand scaffold for crystal engineering aspects

Design of metallosupramolecular materials encompassing more than one kind of supramolecular interaction can become deceptive, but it is necessary to better understand the concept of the controlled formation of supramolecular systems. Herein, we show the structural diversity of the bis-compartmental phenoxo-benzimidazole ligand H3L1 upon self-assembly with variety of d-block metal ions, accounting for factors such as: counterions, pH, solvent and reaction conditions. Solid-state and solution studies show that the parent ligand can accommodate different forms, related to (de)protonation and proton-transfer, resulting in the formation of mono-, bi- or tetrametallic architectures, which was also confirmed with control studies on the new mono-compartmental phenoxo-benzimidazole H2L2 ligand analogue. For the chosen architectures, structural variables such as porous character, magnetic behaviour or luminescence studies were studied to demonstrate how the form of H3L1 ligand affects the final form of the supramolecular architecture and observed properties. Such complex structural variations within the benzimidazole-phenoxo-type ligand have been demonstrated for the first time and this proof-of-concept can be used to integrate these principles in more sophisticated architectures in the future, combining both the benzimidazole and phenoxide subunits. Ultimately, those principles could be utilized for targeted manipulation of properties through molecular tectonics and crystal engineering aspects.

Impedance Spectroscopy as a Powerful Tool for Researching Molybdenum-Based Materials with Schiff Base Hydrazones.

Molybdenum coordination complexes are widely applied due to their biological and pharmacological potential, as well as their performance in different catalytic processes. Parent dioxidomolybdenum Schiff base complexes were prepared via the reaction of [MoO2(acac)2] with a hydrazone Schiff-base tetradentate ligand. A new hydrazone-Schiff base (H2L1 and 2) and its corresponding mononuclear and polynuclear dioxidomolybdenum(VI) complex were synthesized and characterized by spectroscopic methods and elemental analyses, and their thermal behavior was investigated by thermogravimetry. The crystal and molecular structures of H2L2 ligands and the complexes [MoO2(L1)(H2O)], [MoO2(L2)(H2O)], [MoO2(L1)(MeOH)]∙MeOH, [MoO2(L1)(EtOH)]∙EtOH, [MoO2(L1)(2-PrOH)]∙2-PrOH, and [MoO2(L1)]n were determined by single-crystal X-ray diffraction. Using the in situ impedance spectroscopy method (IS), the structural transformations of chosen complexes were followed, and their electrical properties were examined in a wide range of temperatures and frequencies.

M(II) (M=Cu, Ni) Assisted C−S Bond Cleavage and Oxidative Dehydrogenation of Amine on Non‐Innocent Salen Type Ligand Platforms by Varying Nitrogen vs. Sulfur Coordination Atoms

AbstractHerein, we report two newly synthesized salen‐type ligands, 2,3‐bis((3,5‐di‐tert‐butyl‐2‐hydroxybenzyl)thio)maleonitrile (H2L1) and 2,3‐bis((3,5‐di‐tert‐butyl‐2‐hydroxybenzyl)amino)malenonitrile (H4L2), bearing different coordination sites (sulfur vs amine) at maleonitrile tethered moiety to investigate metal mediated non‐innocence chemistry of these ligands. Upon metallation, ligand H2L1 did not yield simple metal‐ligand complex, rather ligand was split into two organic fragments, dithiolene moiety (mnt)2− and phenol moiety via C−S bond cleavage wherein (mnt)2− formed a stable metal complex [M(mnt)2]2−. The C−S bond cleavage was interpreted in terms of strong p(π) … d(π) interaction between metal and dithiolene moiety in H2L1 ligand that invoked the intramolecular rearrangement facilitating C−S bond cleavage. Interestingly, the phenol moiety further transformed to either unprecedented 2,4‐di‐tert‐butyl‐6‐methylenecyclohexa‐2,4‐dienone (i. e. spiro compound; 5) or 2,4‐di‐tert‐butyl‐6‐(hydroxymethyl)phenol (6) depending on the temperature of reaction and type of metal ion used which was further predicted using DFT calculation. On the other hand, combined experimental and DFT studies explained that upon metallation, ligand H4L2 yielded non‐cleavage [M(H2L2)] (3 for M=Cu(II) and 4 for M=Ni(II) ) complex, which slowly oxidized at −NH−CH2‐(amine) region to −N=CH− (imine) in H2L2 ligand under aerobic environment via C−H bond activation, yielding [CuII(L3)] (1) (or [NiII(L3)] (2) complex (H2L3=oxidatively dehydrogenated product of H4L2 ligand.

Synthesis, cytotoxic activity, competitive 7Li NMR studies of potentially N6O2 macroacyclic Schiff base ligands and corresponding manganese (II), zinc (II) and cadmium (II) complexes

Abstract Two potentially N6O2 macroacyclic Schiff base ligands (H2L1 and H2L2) were derived from the condensation of a new polyamine, 2,2′-(4,4′-(propane-1,3-diyl)bis(piperazine-4,1-diyl))diethanamine (A), with 2-Hydroxy- benzaldehyde or 2-hydroxy-3-methoxybenzaldhyde respectively. In the presence of appropriate metal ions, six manganese (II), zinc (II) and cadmium (II) macroacyclic Schiff-base complexes were obtained. All products were characterized by elemental analysis, mass spectrometry and FT-IR, 1H and 13C NMR. Competitive 7Li NMR measurements were employed to monitor the stability of Cd2+, Zn2+ and Mn2+ ions complexes with H2L1 and H2L2 Ligands in methanol and acetonitrile separately. The variation of 7Li chemical shift with [H2L]/[M2+] mole ratios indicated the formation of 1:1 complexes. The formation constants of the resulting complexes were found to be in the order M2+-H2L1 > M2+-H2L2 and Cd2+-H2L > Zn2+-H2L > Mn2+-H2L. The resulting complexes are more stable in acetonitrile than in methanol. The cytotoxic properties of complexes were studied.

New complexes constructed based on (1H-tetrazol-5-yl)phenol: Synthesis, structures and properties

Four new complexes [Ni3(L1)3(H2O)10] (1), [Zn3(L2)3(H2O)]n (2), [Cd(L2)(H2O)]n (3) and [Cd2(HL2)4(H2O)4] (4) have been synthesized by the reaction of 4-(1H-tetrazol-5-yl)phenol (H2L1) and 2-(1H-tetrazol-5-yl)phenol (H2L2) with nickel, zinc, cadmium salts. Complex 1 was synthesized by H2L1 ligand at room temperature conditions, 2 and 3 are synthesized by H2L2 ligand in situ reaction under hydrothermal conditions, 4 is synthesized by H2L2 ligand at room temperature reflux conditions. All of them were characterized by elemental analysis and single-crystal X-ray diffraction, infrared spectrosopy, powder X-ray diffraction and thermogravimetric analysis (TGA). Complexes 1 and 4 are the small-size clusters, the structure of complexes 2 and 3 reveal 2D coordination network. Topologically, complexes 2 and 3 show that binodal networks with a 4-connected and the point symbol of (44·62). In addition, magnetic, fluorescence, and UV–Vis properties of these complexes have been studied.

Studies in stability constants of schiff base hydrazone complexes with transition metal ions. Effect of ligand on seed germination

Spectrophotometric investigation of Cu (II), Ni(II), Co(II), and Fe(III) complexes with 2,4-dihydroxyacetophonone 2,4-dichlorobenzoylhydrazone (H2L1) and 2,4-didydroxy-5-nitroacetophenone 2,4-dichlorobenzoylhydrazone (H2L2) shows 1: 1 and 1: 2 complex formation between the pH range of 3.0 to 6.0 and also studied by jobs variation method at 0.1 M ionic strength at 30 ± 1°C specrtophotometrically. The conditional stability constants are determined for 1: 1 complexes. Effect of H2L1 and H2L2 ligand and its complexes on seed germination is studied.

Two novel mono- and heptanuclear Ni(II) complexes constructed from new unsymmetric and symmetric Salamo-type bisoximes – Synthetic, structural and spectral studies

Two novel mono- and heptanuclear Ni(II) complexes, [Ni(HL1)2(EtOH)2]·2EtOH (1) and [Ni7(L2)3(μ3-OMe)2(μ3-OH)6(MeOH)6] (2), have been synthesized by the reaction of Ni(II) acetate with H2L1 and H2L2, respectively. In the Ni(II) complex 1, the ligand H2L1 was partially deprotonated, only NO donor atoms of one salicylidene moiety of the (HL1)− unit coordinate to Ni(II) atom. While all the three H2L2 ligands in the Ni(II) complex 2 were completely deprotonated. The seven Ni(II) atoms are all hexa-coordinated, and have two coordination environments. The fluorescence properties of the ligands, the Ni(II) complexes 1 and 2 have been discussed.

Geometrical, molecular docking and potentiometric studies of sulfoxine and its new azo derivative with their metal complexes

A new azo sulfoxine ligand was produced from coupling reaction between 8-hydroxyquinoline-5-sulfonic acid (H2L1) and 4-amino antipyrene. The structure of the new azo ligand, 7-azo(-4-antipyrene)-8-hydroxyquinoline-5-sulfonic acid (H2L2), was confirmed by various physico-chemical techniques. The molecular structures of H2L1 and its azo derivative (H2L2) were optimized theoretically and the quantum chemical parameters were calculated. Molecular docking was used to predict the efficiency of binding between each ligand and the breast cancer mutant receptor (3hb5-Oxidoreductase). The acid dissociation constants (pKH) of H2L1 and H2L2 ligands have been determined potentiometrically at different temperatures. The stability constants (log K) of some transition metal ions (Mn2+, Co2+, Ni2+ and Cu2+) with the investigated ligands have been determined. The effect of the azo group on both, the dissociation constants of H2L2 ligand and the stability constants of its complexes has been discussed. The thermodynamic parameters (ΔG, ΔH and ΔS) were derived and discussed at different temperatures. The formation of the metal complexes was found to be spontaneous, endothermic and entropically favorable. The relationships between the stability constants and ΔG values of all investigated complexes and their ionic radii have been discussed and correlated.

Substituent and Temperature Effect on the Assemblies of Three Lead(II) Coordination Polymers based on Asymmetrical Biphenyl Tritopic Ligands

AbstractThree Pb‐based metal‐organic frameworks, [Pb6(L1)4]·H2O (1), [Pb2(L2)2(H2O)]·H2O (2), and [Pb(L2)(H2O)]·H2O (3) were constructed based on two asymmetrical tritopic ligands, 3‐(2′,5′‐dicarboxylphenyl)benzoic acid (H3L1) and 3‐(2′,5′‐dicarboxylphenyl)pyridine acid (H2L2), under hydrothermal conditions. The substituents on the two ligands and the induced temperature had effects on the resulting structures. All of the complexes were structurally characterized by X‐ray diffraction analyses and further identified by infrared spectra, elemental analyses, powder X‐ray diffraction, and thermogravimetric analyses. Complexes 1 and 3 are 3D frameworks, which construct from 1D inorganic Pb–O–Pb rod‐shaped secondary building units (SBUs) and H3L1/H2L2 ligands as pillars. Complex 2 is a 3D framework based on discrete tetranuclear Pb4(COO)8 clusters SBUs and H2L2 ligands. The effects of both the substituent groups on the aromatic rings and the reaction temperature are discussed in details. The fluorescence properties and thermal stabilities of complexes 1–3 were also measured.

Synthesis, spectral, X-ray diffraction, antimicrobial studies, and DNA binding properties of binary and ternary complexes of pentadentate N2O3 carbohydrazone ligands

Two pentadentate carbohydrazone ligands, H2L1 and H2L2, were prepared by the reaction of the bifunctional compound carbohydrazide with 2-hydroxy-5-nitrobenzaldehyde and 2-hydroxy-1-naphthaldehyde, respectively. Reactions of the ligands with oxovanadium(IV), cerium(III), thorium(IV), and dioxouranium(VI) ions yielded binary complexes. Reactions of the ligands with the dioxouranium(VI) ion in the presence of secondary ligands (8-hydroxyquinoline, glycine, salicylaldehyde, or benzoylacetone) yielded ternary complexes. The ligands and metal complexes were characterized by different techniques such as elemental and thermal analyses, IR, 1H and 13C NMR, electronic, ESR, mass spectra, and powder XRD as well as magnetic susceptibility and conductivity measurements. The coordinating sites are phenolic oxygen, azomethine nitrogen, and carbonyl oxygen. In complexes, the ligands act as dibasic pentadentate except ternary dioxouranium(VI) complexes, obtained using glycine or benzoylacetone, in which the ligands act as monobasic pentadentate. The XRD patterns for the H2L1 ligand, its binary dioxouranium(VI) complex, and its 8-hydroxyquinoline ternary complex indicate crystalline nature and the grain size was estimated. The H2L1 ligand and its binary complex have triclinic systems while the ternary complex has a monoclinic system with different unit-cell parameters. The ligands and some of their metal complexes showed antimicrobial activity toward some Gram-positive and Gram-negative bacteria, yeast (Candida albicans), and fungus (Aspergillus fumigatus), and MIC values were determined. The DNA binding properties of the oxovanadium(IV) complexes of H2L1 and H2L2 ligands were investigated by electronic absorption spectroscopy and viscosity measurements. The results indicated that these complexes bind to DNA via an intercalation binding mode with an intrinsic binding constant K b of 2.55 × 104 and 3 × 104 M−1, respectively.

Mono- and binuclear copper(II) complexes of new hydrazone ligands derived from 4,6-diacetylresorcinol: Synthesis, spectral studies and antimicrobial activity

Two new hydrazone ligands, H2L1 and H2L2, were synthesized by the condensation of 4,6-diacetylresorcinol with 3-hydrazino-5,6-diphenyl-1,2,4-triazine and isatin monohydrazone, respectively. The structures of the ligands were elucidated by elemental analyses, IR, 1H NMR, electronic and mass spectra. Reactions of the ligands with several copper(II) salts, including AcO−, NO3-, SO42-, Cl− and Br− afforded mono- and binuclear metal complexes. Also, the ligands were allowed to react with Cu(II) ion in the presence of a secondary ligand (L′) [N,O-donor; 8-hydroxyquinoline, N,N-donor; 1,10-phenanthroline or O,O-donor; benzoylacetone]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and ESR spectra as well as conductivity and magnetic susceptibility measurements. The ESR spin Hamiltonian parameters of some complexes were calculated. The spectroscopic data showed that the H2L1 ligand acts as a neutral or monobasic tridentate ligand while the H2L2 ligand acts as a bis(monobasic tridentate) ligand. The coordination sites with the copper(II) ion are phenolic oxygen, azomethine nitrogen and triazinic nitrogen (H2L1 ligand) or isatinic oxygen (H2L2 ligand). The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligands and some metal complexes showed antimicrobial activity.

Synthesis, structural characterization and in vitro cytotoxicity of diorganotin complexes with Schiff base ligands derived from 3‐hydroxy‐2‐naphthoylhydrazide

A series of diorganotin complexes with Schiff base ligands, (E)‐N′‐(5‐bromo‐2‐hydroxybenzylidene)‐3‐hydroxy‐2‐naphthohydrazide, H2L1, and (E)‐N′‐(5‐chloro‐2‐hydroxybenzylidene)‐3‐hydroxy‐2‐naphthohydrazide, H2L2, were synthesized and characterized by elemental analysis, IR, 1H, 13C and 119Sn NMR spectroscopy. The molecular structures of the complexes, [(5‐bromo‐2‐oxidobenzylidene)‐3‐hydroxy‐2‐naphthohydrazidato]di(o‐chlorobenzyl)tin(IV) 6 and [(5‐chloro‐2‐oxidobenzylidene)‐3‐hydroxy‐2‐naphthohydrazidato]dibutyltin(IV) 9, were determined through single‐crystal X‐ray diffraction and revealed a distorted trigonal‐bipyramidal configuration. The in vitro cytotoxic activity of the Schiff bases and their diorganotin complexes was also evaluated against several human carcinoma cell lines, namely HT29 (human colon carcinoma cell line), SKOV‐3 (human ovarian cancer cell line), MCF7 (hormone‐dependent breast carcinoma cell line) and MRC5 (non‐cancer human fibroblast cell line). [(5‐Bromo‐2‐oxidobenzylidene)‐3‐hydroxy‐2‐naphthohydrazidato]dibutyltin(IV) 2 and [(5‐bromo‐2‐oxidobenzylidene)‐3‐hydroxy‐2‐naphthohydrazidato]dibenzyltin(IV) 5 were the most active diorganotin complexes of H2L1 ligand. Among the diorganotin complexes of H2L2 ligand, [(5‐chloro‐2‐oxidobenzylidene)‐3‐hydroxy‐2‐naphthohydrazidato]dicyclohexyltin(IV) 11 showed good cytotoxic activity against all the tested cell lines. As such, the above compounds can be considered agents with potential anticancer activities, and can therefore be investigated further in in vitro or in vivo anticancer studies. Copyright © 2012 John Wiley & Sons, Ltd.

Spectral, thermal and biological studies of Mn(II) and Cu(II) complexes with two thiosemicarbazide derivatives

Two derivatives of thiosemicarbazide were prepared. Their complexes were prepared using Mn(II) and Cu(II) salts. All the isolated complexes are characterized using the following spectra: IR, UV–Vis, Mass, 1H NMR and X-ray diffraction. Magnetic measurements and thermal analysis are the other additive tools for complete investigation. Mononuclear and binuclear complexes are proposed based on elemental analysis mainly. The IR spectra offer the mode of coordination of each ligand with each metal ion. The electronic spectra and magnetic measurements are proposing the structural geometry of the investigated complexes. The octahedral geometry proposed for Mn(II) complexes but the square–planar for Cu(II) complexes. The 1H NMR spectra were done for all organic compounds used in this study and displaying the most suitable tautomer of them. X-ray diffraction of H2L1 and its complexes show their amorphous nature but H2L2 ligand and its complexes show their nanocrystalline nature. The TG analysis was used to prove the presence of solvent molecules attached with the complexes as covalently or physically. Finally, the biological investigation was carried out for H2L2 ligand and its complexes and displaying the inhibition activity of Cu(II) complex than the Mn(II) one.

Spectral characterization and biological evaluation of Schiff bases and their mixed ligand metal complexes derived from 4,6-diacetylresorcinol

In the present study two new series of Copper(II), Nickel(II) and Cobalt(II) complexes with two newly synthesized Schiff base ligands 4,6-bis(1-(4-bromophenylimino)ethyl)benzene-1,3-diol (H2L1), 4,6-bis(1-(4-methoxyphenylimino) ethyl)benzene-1,3-diol (H2L2) and organic ligands 8-hydroxy quinoline, 1,10-phenanthroline have been prepared. The Schiff bases H2L1 and H2L2 ligands were synthesized by the condensation of 4,6-diacetyl resorcinol with 4-bromo aniline and 4-methoxy aniline. The ligands and their metal complexes have been characterized by FT-IR, Mass, 1H NMR, UV–Vis., elemental analysis, ESR and Thermal gravimetric analysis. The Schiff base and their metal complexes were tested for antimicrobial activity against gram positive bacteria Staphylococcus aureus, Streptococcus pyogenes and gram negative bacteria Escherichia coli, Pseudomonas aeruginosa and fungus Candida albicans, Aspergillus niger and Aspergillus clavatus using Broth Dilution Method.

Pd-Salen and Pd-Salan complexes: Characterization and application in styrene polymerization

Abstract Two new Pd2+ complexes based on the Salen-type H2L1 or Salan-type H2L2 ligand (H2L1 = N,N′-Bis(3-methoxy-salicylidene)phenylene-1,2-diamine), H2L2 = 1,2-Bis(2-hydroxyl-3-methoxy-phenyl)methylamino-benzene), were synthesized and characterized by FT-IR, 1H NMR and X-ray crystallography. They were shown to catalyze the polymerization of styrene, giving the syndio-enriched atactic polystyrenes with moderate molecular weights and narrow molecular weight distributions. The detailed stereoregular analysis of the polymeric products shows that the slight increase in electrophilicity or Lewis acidity of active species by the reduction from Salen-type to Salan-type ligand endows the distinctive increase of the stereoselectivities besides the increase of the catalytic activities.

Synthesis and spectroscopic studies of new binuclear transition metal complexes of Schiff bases derived from 4,6-diacetylresorcinol

Two new series of copper(II), nickel(II), cobalt(II), zinc(II), iron(III), chromium(III), vanadyl(IV) and uranyl(VI) complexes with two bifunctional tridentate Schiff base, H4L1 and H2L2 ligands have been prepared. The Schiff base, H4L1 and H2L2, ligands were synthesized by the condensation of 4,6-diacetylresorcinol with o-aminophenol or o-phenylenediamine. The ligands are either di- or tetra-basic with two symmetrical sets of either OON or NNO tridentate chelating sites. The ligands and their metal complexes have been characterized by elemental analysis, 1H-n.m.r., FT-IR, mass, electronic, esr spectra and thermal gravimetric analysis and magnetic susceptibility. With the exception of CoII ion with H2L2 which afforded a trinuclear complex, a variety of binuclear complexes for the rest of the metal complexes were obtained with the ligands in its di- or tetra-deprotonated forms. The bonding sites are the azomethine and amino nitrogen atoms, and phenolic oxygen atoms. The metal complexes exhibit different geometrical arrangements such as square planar, tetrahedral, square pyramid and octahedral arrangement.

A family of mixed-ligand oxovanadium(V) complexes incorporating tridentate ONO donor hydrazone ligands derived from acetylhydrazide and 2-hydroxybenzaldehyde/2-hydroxyacetophenone

In the title family the tridentate ONO donor ligands are the fully deprotonated forms of acetylhydrazones of 2-hydroxybenzaldehyde (H2L1) and 2-hydroxyacetophenone (H2L2) (general abbreviation H2L), while bidentate mononegative OO donor ligands are the deprotonated salicylaldehyde (Hsal), vanillin (Hvan) and monodeprotonated 1,2-ethanediol (H2ed) (general abbreviation HB). The reaction of VIVO(acac)2 with H2L and Hsal or Hvan in equimolar ratio in MeOH afforded the complexes of the type [VVO(L)(B)], (1)–(4). The reaction of VIVO(acac)2 with H2L1 (in an equimolar ratio) and an excess of H2ed in MeOH yielded the complex [VVO(L1)(Hed)], (5) but the similar reaction with H2L2 ligand failed to produce such a type of complex. Complexes have been characterized by elemental analyses and by i.r., n.m.r. and u.v.-vis. spectroscopies. All the complexes are diamagnetic and display only LMCT bands. 1H-n.m.r. spectral data indicate that complexes (1)–(4) exist in two isomeric forms [(1A), (1B); (2A), (2B); (3A), (3B) and (4A), (4B)] in different ratios in CDCI3 solution. Complexes (1)–(4) display a quasi-reversible one electron reduction peak in the −0.06 to +0.05 V versuss.c.e. region in CH2CI2 solution and (5) displays an irreversible reduction peak at −0.46 V versuss.c.e. in DMF solution. The trend in the redox potential values has been correlated with the basicity of both the primary and auxiliary ligands.

Complexes of iron(II), iron(III) and zinc(II) with condensation derivatives of 2-acetylpyridine and oxalic or malonic dihydrazide. Crystal structure of tris[(1-(2-pyridyl)ethylidene)hydrazine]iron(II) perchlorate

Complexes of zinc and iron with N′, N′2-bis[(1E)-1-(2-pyridyl)ethylidene]ethanedihydrazide (H2L1) and N′ ,N′2-bis[(1E)-1-(2-pyridyl)ethylidene]propanedihydrazide (H2L2) were prepared. ZnII complexes with both ligands have an octahedral geometry. In the complex of ZnII with H2L1, the ligand is coordinated as a tridentate species in the monoanionic form, building two five-membered rings around ZnII. Three remaining coordination sites are occupied by water molecules, and in the outer sphere there is a ClO 4− ion. In the other ZnII complex, the H2L2 ligand is coordinated in the enol form as a tetradenate species, forming a five-memebered, a six-membered and a seven-membered ring, the remaining coordination sites being occupied by water molecules, while in the outer sphere there are two ClO 4− ions. The FeIII complex with H2L2 is a high-spin octahedral complex. The ligand is coordinated in the enol form, in a tetradentate fashion via pyridine and hydrazone nitrogens. The remaining two coordination sites in the complex are occupied by water molecules and a Cl− ion, and in the outer sphere there are two Cl− anions. The octahedral FeIII complex obtained from the reaction of FeCl3·6H2O and H2L1 in absolute ethanol has the formula [Fe(HL1)Cl2(H2O)]·1.5H2O. However, during coordination of the H2L1 ligand to FeIII in water, oxidative degradation of the side chain (–CO–CO–) and reduction of FeIII to FeII occurs, affording octahedral tris(1-(2-pyridyl)ethylidenehydrazine] ironII perchlorate, as confirmed by X-ray structure analysis.