Iron Complexes Research Articles

Redox-Neutral, Iron-Mediated Directed C-H Activation: General Principles and Mechanistic Insights.

Experimental and computational studies have been conducted and established the general principles for enabling redox-neutral C-H activation by iron(II) complexes. The idealized octahedral iron(II) dimethyl complex, (depe)2Fe(CH3)2 (depe = 1,2-bis(diethylphosphino)ethane) promoted the directed, regioselective ortho C(sp2)-H methylation of pivalophenone. The rate of the iron(II)-mediated C(sp2)-H functionalization depended on the lability of L-type phosphine ligands, the spin state of the iron center, and the size of the X-type ligands (halide, hydrocarbyl) in P4FeIIX2 complexes. The C(sp2)-H alkylation reaction proved general among multiple substrates with directing groups including carbonyl, imines and pyridines. Among these, ketones and aldehydes were identified as optimal and were compatible with various steric environments and presence of acidic α-hydrogens. With stronger nitrogen donors, higher barriers for product-forming reductive elimination were observed. The effect of orbital hybridization on the chemoselectivity of C-H activation through a σ-CAM pathway by dn>0 transition metals was also established by studying the stoichiometric reactivity of the differentially substituted (depe)2Fe(Me)R complexes (R = alkyl, aryl), where the Fe-R bond with greater s-character preferentially promoted selective C-H activation. Deuterium labeling and kinetic studies, coupled with computational analysis, supported a pathway involving phosphine dissociation and rate-determining C-H bond activation, leading to the observed products.

Speciation Controls the Kinetics of Iron Hydroxide Precipitation and Transformation at Alkaline pH.

The formation of energetically favorable and metastable mineral phases within the Fe-H2O system controls the long-term mobility of iron complexes in natural aquifers and other environmentally and industrially relevant systems. The fundamental mechanism controlling the formation of these phases has remained enigmatic. We develop a general partial equilibrium model, leveraging recent synchrotron-based data on the time evolution of solid Fe(III) hydroxides along with aqueous complexes. We combine thermodynamic considerations and particle-morphology-dependent kinetic rate equations under full consideration of the aqueous phase in disequilibrium with one or more of the forming minerals. The new model predicts the rate of amorphous 2-line ferrihydrite precipitation, dissolution, and overall transformation to crystalline goethite. It is found that the precipitation of goethite (i) occurs from solution and (ii) is limited by the comparatively slow dissolution of the first forming amorphous phase 2-line ferrihydrite. A generalized transformation mechanism further illustrates that differences in the kinetics of Fe(III) precipitation are controlled by the coordination environment of the predominant Fe(III) hydrolysis product. The framework allows modeling of other iron(bearing) phases across a broad range of aqueous phase compositions.

Dyeing behaviour of iron(III)-gallic acid complexes on wool as function of pH-dependent iron(III)-complex stoichiometry

Iron complexes with polyphenolics e.g. gallotannins and flavonoids have been used since ancient times for coloration of textiles, painting and preparation of inks. The composition of iron gall inks on historical artefacts has been investigated with modern instrumental methods. However the dyeing behaviour of iron-complexes with polyphenols still bases on empirical knowledge. In this study Fe(III)-complexes with gallic acid were used as model system to elucidate their pH dependent sorption and dyeing behaviour on wool. At dyebath pH 3 high sorption of Fe(III)-gallic acid complexes was observed, however darker dyeings were obtained at dyebath pH 4. Model calculations for the complex species present in the dyebath indicated the presence of the binary complex [Fe(III)(GA2−)]+ as main species at pH 3, while at pH 4 the ternary species [Fe(III)(GA2−)2]- prevails. The dye sorption bases on Van-der-Waals forces, while ionic interactions between Fe(III)-complex and keratin are of minor relevance. The elaborated theoretical model also explains the influence of dyebath pH in dyeing with gallotannins, polyphenols and flavonoids in presence of iron salts and thus is of particular relevance for improved utilisation of these natural colorants.

Gradual spin crossover behavior encompasing room temperature in an iron(II) complex based on a heteroscorpionate ligand.

In this paper, we report the synthesis of six novel triazole-based heteroscorpionate ligands based on heterocycle metathesis reactions and their iron(II) complexes. Single crystal structure analyses were performed, the spectroscopic and magnetic properties of the obtained complexes were studied and their spin crossover-structural relationships were compared to those obtained for their pyrazole-based analogues reported in the literature. In particular, the amino derivative complex bis[hydrobis(pyrazol-1-yl)(3-amino-1,2,4-triazol-1-yl)]iron(II) obtained by post-synthetic catalytic nitro-group reduction under pressure of hydrogen in an autoclave presents a scarce gradual spin crossover behavior at room temperature. The profile of the SCO curve can be explained by the presence of only relatively weak H bonds, spreading only in one dimension. Among the interesting spin transition behaviors observed for the different complexes, such stable, complete and gradual spin crossover at room temperature makes this neutral complex a good candidate for sublimation and future investigation as an active element notably for thermoreflectance-based surface microthermometry applications.

Homeostatic nanomedicine: Protein S-nitrosylation dyshomeostasis dominated oncotherapy based on a tumor-microenvironment-activated nanoparticle

Nitric oxide (NO) holds promise as a therapeutic agent in oncotherapy, yet its efficacy is hindered by low bioavailability, concentration-dependency, and tumor resistance to nitrosative stress. To overcome these limitations, herein, we propose a novel strategy aimed at specifically breaking the protein S-nitrosylation homeostasis of tumors. An acid-responsive nanoplatform comprising amorphous iron / mesoporous silica (AMSP) is constructed to orchestrate synergistic anti-tumor effect of Fe2+ and NO. Activating by the tumor microenvironment, nanopores of AMSP facilitate the in-situ generation of dinitrosyl iron complexes, promoting the physiological stability of NO and protein S-nitrosylation via transnitrosylation. Moreover, the released Fe2+ accelerate reactive oxygen species accumulation in tumor cells, which not only derives stronger nitrating reagents, but also inhibits the denitrosylation reaction triggered by tumor-expressed reducing species. The multiple effects of AMSP induce excessive cellular S-nitrosylation, thereby guiding an untraditional apoptotic pathway, glyceraldehyde-3-phosphate dehydrogenase S-nitrosylation mediated nuclear translocation and protein degradation. Overall, our findings offer a new paradigm of homeostatic nanomedicine, potentially advancing oncotherapy modalities.

Stereoelectronic Tuning of Bioinspired Nonheme Iron(IV)-Oxo Species by Amide Groups in Primary and Secondary Coordination Spheres for Selective Oxygenation Reactions.

Two mononuclear iron(II) complexes, [(6-amide2-BPMEN)FeII](OTf)2 (1) and [(6-amide-Me-BPMEN)FeII(OTf)](OTf) (2), supported by two BPMEN-derived (BPMEN = N1,N2-dimethyl-N1,N2-bis(pyridine-2-yl-methyl)ethane-1,2-diamine) ligands bearing one or two amide functionalities have been isolated to study their reactivity in the oxygenation of C-H and C═C bonds using isopropyl 2-iodoxybenzoate (iPr-IBX ester) as the oxidant. Both 1 and 2 contain six-coordinate high-spin iron(II) centers in the solid state and in solution. The 6-amide2-BPMEN ligand stabilizes an S = 1 iron(IV)-oxo intermediate, [(6-amide2-BPMEN)FeIV(O)]2+ (1A). The oxidant (1A) oxygenates the C-H and C═C bonds with a high selectivity. Oxidant 1A, upon treatment with 2,6-lutidine, is transformed into another oxidant [{(6-amide2-BPMEN)-(H)}FeIV(O)]+ (1B) through deprotonation of an amide group, resulting in a stronger equatorial ligand field and subsequent stabilization of the triplet ground state. In contrast, no iron-oxo species could be observed from complex 2 and [(6-Me2-BPMEN)FeII(OTf)2] (3) under similar experimental conditions. The iron(IV)-oxo oxidant 1A shows the highest A/K selectivity in cyclohexane oxidation and 3°/2° selectivity in adamantane oxidation reported for any synthetic nonheme iron(IV)-oxo complexes. Theoretical investigation reveals that the hydrogen bonding interaction between the -NH group of the noncoordinating amide group and Fe═O core smears out the equatorial charge density, reducing the triplet-quintet splitting, and thus helping complex 1A to achieve better reactivity.

Synergistic inhibition effect of Chlorella sp. and benzotriazole on the corrosion of Q235 carbon steel in alkaline artificial seawater

The interaction of microalgae on the reinforced concrete with corrosion inhibitor is not well understood. Moreover, the inhibition role of microalgae on corrosion has been reported in recent years. In this study, the corrosion inhibition behavior of Q235 carbon steel (CS) due to the presence of Chlorella sp. and benzotriazole (BTA) in alkaline artificial seawater was investigated by means of weight loss, electrochemical measurements including open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization curves, and surface analysis including scanning electron microscopy, energy dispersion spectrometer, and X-ray photoelectron spectroscopy. The results of reduced corrosion rates in the algae-BTA system demonstrated that Chlorella sp. could facilitate the corrosion inhibition efficiency of BTA on the CS specimens. Moreover, polarization measurement showed the algae-BTA system had a mixed-type corrosion inhibition effect. The mechanisms of inhibition were proposed to be the precipitation of iron complexes such as Fe-BTA-EPS and Fe-BTA and iron compounds on the steel surface in the presence of the microalgae and BTA–. This study highlights the application of CS corrosion control by combining biological and chemical approaches that can be used for future research and practice, rather than purely chemical approaches.

Examining the Effects of Ailing Ajaokuta Steel Plant on Industrialization and Technological Growth in Nigeria

Nigeria, out of the exigency to feed her bulging population established a mega iron and steel complex in Ajaokuta, Kogi state to drive technological innovation for productive activities in the country. The steel project was designed to serve as a catalyst for growth and development of industries as well as other sectors of the Nigerian economy. While the existing literature is replete with studies focusing on the factors undermining the operations of Ajaokuta Steel Plant, the effects of underutilized Ajaokuta Steel Plant on the Nigerian economy has received less academic attention. It is against this backdrop that the study examined the effects of ailing Ajaokuta Steel Plant on industrialization and development of technology in Nigeria. The study relied on documentary method of data collection and qualitative descriptive method of data analysis. The study revealed among others that the ailing state of Ajaokuta Steel Plant has adversely affected the growth of indigenous technologies and industries in Nigeria. The failure of the Ajaokuta Steel Plant to produce iron and steel products for the creation of indigenous means of labour has made the Nigerian economy an outrageous consumer of foreign techs and manufactured products. This has not only halted country’s quest for industrialization but has truncated its ability to manufacture what it consumes.

Mechanistic insights into multimetal synergistic and electronic effects in a hexanuclear iron catalyst with a [Fe3(μ3-O)(μ2-OH)]2 core for enhanced water oxidation.

Multinuclear molecular catalysts mimicking natural photosynthesis have been shown to facilitate water oxidation; however, such catalysts typically operate in organic solutions, require high overpotentials and have unclear catalytic mechanisms. Herein, a bio-inspired hexanuclear iron(III) complex I, Fe6(μ3-O)2(μ2-OH)2(bipyalk)2(OAc)8 (H2bipyalk = 2,2'-([2,2'-bipyridine]-6,6'-diyl)bis(propan-2-ol); OAc = acetate) with desirable water solubility and stability was designed and used for water oxidation. Our results showed that I has high efficiency for water oxidation via the water nucleophilic attack (WNA) pathway with an overpotential of only ca. 290 mV in a phosphate buffer of pH 2. Importantly, key high-oxidation-state metal-oxo intermediates formed during water oxidation were identified by in situ spectroelectrochemistry and oxygen atom transfer reactions. Theoretical calculations further supported the above identification. Reversible proton transfer and charge redistribution during water oxidation enhanced the electron and proton transfer ability and improved the reactivity of I. Here, we have shown the multimetal synergistic and electronic effects of catalysts in water oxidation reactions, which may contribute to the understanding and design of more advanced molecular catalysts.

Co-Delivery of Renal Clearable Cerium Complex and Synergistic Antioxidant Iron Complex for Treating Sepsis.

The mononuclear phagocytic system clears the circulating inorganic nanomaterials from the bloodstream, which raises concerns about the chronic toxicity of the accumulated metal species. A better understanding of the behavior of each metal after systemic injection is thus required for clinical translations. This study investigates the significance of the metal-ligand interaction on the accumulation of cerium and demonstrates that only the form in which cerium is coordinated to a multidentate chelator with a strong binding affinity does not accumulate in major organs. Specifically, cerium complexed with diethylenetriamine pentaacetic acid (DTPA) forms renally excretable nanoparticles in vivo to circumvent the leaching of cerium ions, whereas weakly coordinated cerium-based nanomaterials produce insoluble precipitates upon encountering physiological phosphate anions. Ceria-based renally clearable nanoparticles (CRNs) derived from cerium-DTPA are utilized as the antioxidant pair with iron-DTPA, in which their combination leverages the Fenton reaction to synergistically scavenge hydrogen peroxide. This reduces the gene expression of pro-inflammatory factors in the macrophages activated with lipopolysaccharide as well as improves the survival rate of septic mice by alleviating the systemic inflammatory response and its downstream tissue injury in the liver, spleen, and kidneys. This study demonstrates that CRNs combined with iron-DTPA can be utilized as nonaccumulative nanomedicines for treating systemic inflammation, thereby overcoming the limitations of conventional ceria nanoparticle-based treatments.

Highly Stable Alkaline All‐Iron Redox Flow Batteries Enabled by Disulfonated Ligands Chelation

AbstractAlkaline all‐iron flow batteries possess intrinsic safety and low cost, demonstrating great potential for large‐scale and long‐duration energy storage. However, their commercial application is hindered by the issue of capacity decay resulting from the decomposition of iron complexes and ligand crossovers. In this paper, an robust anolyte Fe(TEA‐2S) is reported, which is formed by chelating iron ions with the sulfonate‐enriched ligand (TEA‐2S) in alkaline environment. By skillfully designing the ligands, the binding energy of the iron complexes increases and ligand crossovers are suppressed, making the iron complexes highly stable in the charge–discharge cycles. Alkaline all‐iron flow batteries coupling with Fe(TEA‐2S) and the typical iron‐cyanide catholyte perform a minimal capacity decay rate (0.17% per day and 0.0014% per cycle), maintaining an average coulombic efficiency of close to 99.93% over 2000 cycles along with a high energy efficiency of 83.5% at a current density of 80 mA cm−2. In addition, Fe(TEA‐2S) exhibits high solubility of up to 1.85 м (with a theoretical capacity of up to 49.58 Ah L−1), even at low temperatures as extreme as −30 °C. This work demonstrates a promising pathway toward achieving long‐duration and large‐scale energy storage.

Synthesis, Urease Inhibition, Molecular Docking, and Optical Analysis of a Symmetrical Schiff Base and Its Selected Metal Complexes.

Designing and developing small organic molecules for use as urease inhibitors is challenging due to the need for ecosystem sustainability and the requirement to prevent health risks related to the human stomach and urinary tract. Moreover, imaging analysis is widely utilized for tracking infections in intracellular and in vivo systems, which requires drug molecules with emissive potential, specifically in the low-energy region. This study comprises the synthesis of a Schiff base ligand and its selected transition metals to evaluate their UV/fluorescence properties, inhibitory activity against urease, and molecular docking. Screening of the symmetrical cage-like ligand and its metal complexes with various eco-friendly transition metals revealed significant urease inhibition potential. The IC50 value of the ligand for urease inhibition was 21.80 ± 1.88 µM, comparable to that of thiourea. Notably, upon coordination with transition metals, the ligand-nickel and ligand-copper complexes exhibited even greater potency than the reference compound, with IC50 values of 11.8 ± 1.14 and 9.31 ± 1.31 µM, respectively. The ligand-cobalt complex exhibited an enzyme inhibitory potential comparable with thiourea, while the zinc and iron complexes demonstrated the least activity, which might be due to weaker interactions with the investigated protein. Meanwhile, all the metal complexes demonstrated a pronounced optical response, which could be utilized for fluorescence-guided targeted drug delivery applications in the future. Molecular docking analysis and IC50 values from in vitro urease inhibition screening showed a trend of increasing activity from compounds 7d to 7c to 7b. Enzyme kinetics studies using the Lineweaver-Burk plot indicated mixed-type inhibition against 7c and non-competitive inhibition against 7d.

Synthesis and Magnetic Properties of Spherical Maghemite Nanoparticles with Tunable Size and Surface Chemistry.

We report the synthesis of uniform populations of spherical maghemite nanoparticles by thermal decomposition of iron precursors with tunable diameters centered at 3.3, 7.5, and 12.0 nm and tunable surface chemistry. The three stabilizing ligands were fatty acids with three different alkyl chain lengths (18, 12, and 8 carbon atoms). The unprecedented accurate control of the surface chemistry is made possible by the use of three types of iron complexes, that is, iron oleate (C18), iron dodecanoate (C12), and iron octanoate (C8), associated with fatty acid ligands having the same alkyl chain length, that is, oleic acid (C18), dodecanoic acid (C12), and octanoic acid (C8). Since the thermal decomposition of the iron precursor varies with the chain length, no general rules can be applied to control the nanoparticle size, but optimal synthesis conditions have been investigated to induce the growth of nanoparticles with three different surface chemistries, keeping the diameters centered at 3.3, 7.5, and 12.0 nm. Finally, structural characterization of the nine populations of maghemite nanoparticles was performed by transmission electron microscopy and X-ray diffraction, and magnetic properties were determined by using SQUID magnetometry.

A Mixed Aryl/Amide Complex of Iron(II)

The combined incorporation of a labile and a stabilizing ligand in a metal‐organic precursor is of interest for the synthesis of low valent ligated (hetero)metallic clusters. The heteroleptic aryl/amide iron (II) complex [Fe2(Mes)2(BTSA)2] (1) was synthesized by equimolar mixing of [Fe2(Mes)4] with [Fe2(BTSA)4]. (VT)‐NMR‐, UV‐Vis‐ and SC‐XRD‐analysis combined with DFT calculations revealed a dimeric structure with terminal bis(trimethylsilyl)amide‐ and bridging mesityl‐ligands in solution and as well in the solid phase. The treatment of [Fe2(BTSA)4] with the carbenoid group 13 metallo‐ligand GaCp* is known to yield simply adducts. In contrast, monitoring the reactions of [Fe2(Mes)4] and [Fe2(Mes)2(BTSA)2] (1) with GaCp* by liquid injection field desorption mass spectrometry (LIFDI‐MS) suggest formation of a broader variety of bimetallic Fe‐Ga‐species with iron formally reduced to iron (I) or iron (0). However, the product distribution obtained using the heteroleptic compound 1 indicates combined reactivity of the homoleptic congeners by showing larger species with variations of Fe/Ga ratios towards the formation of Fe/Ga clusters. This blended behavior is assigned to the more labile mesityl ligand and the more stabilizing BTSA‐ligand.

Assessing and applying DFT approaches for geometries and UV–Vis absorption spectra of tetragonal iron(II) complexes

Assessing and applying DFT approaches for geometries and UV–Vis absorption spectra of tetragonal iron(II) complexes

A new insight on the effects of Schiff Base Iron (III) complexes in breast cancer cells for clinical radiotherapy

PurposeBreast cancer is a significant global health concern, and researchers strive to enhance radiotherapy outcomes while minimizing the side effects. Schiff Base Iron (III) Complexes are one of the prospective elements that can be used as radiosensitizer or radioprotective agents in cancer radiotherapy. This study investigates the potential effects of Schiff base (ligand 2; L2) with Fe(III) in MCF-7 breast cancer cells under clinical radiotherapy treatment. MethodsThe effects of the Schiff Base Iron (III) Complexes were measured using clonogenic assay with MCF-7 breast cancer cells. The cells were irradiated with megavoltage 6 MV photon, 6 MeV electron and high dose rate (HDR) brachytherapy with 192Ir source at different doses. Intercellular localization of Fe(III)-L2 complexes and antioxidant activities were also investigated. ResultsThe Fe(III)-L2 complexes were observed to be internalized by cellular nuclei without any effects on the cells. Interestingly, the Fe(III)-L2 complexes indicate radioprotective effects which provide intriguing insight towards application of metal ions complexes as radioprotector in cancer radiotherapy. The Fe(III)-L2 complexes also exhibit scavenging activities of free radical which further proved the antioxidative properties and radioprotective effects. ConclusionThe Fe(III)-L2 complexes show the radioprotective effects and antioxidant properties in MCF-7 cells, particularly for HDR brachytherapy. The findings suggest potential applications of the Fe(III)-L2 complexes as radioprotector agents in clinical radiotherapy.

A bis-Phenolate Carbene-Supported bis-μ-Oxo Iron(IV/IV) Complex with a [FeIV(μ-O)2FeIV] Diamond Core Derived from Dioxygen Activation.

The diiron(II) complex, [(OCO)Fe(MeCN)]2 (1, MeCN = acetonitrile), supported by the bis-phenolate carbene pincer ligand, 1,3-bis(3,5-di-tert-butyl-2-hydroxyphenyl)benzimidazolin-2-ylidene (OCO), was synthesized and characterized by single-crystal X-ray diffraction, 1H nuclear magnetic resonance, infrared (IR) vibrational, ultraviolet/visible/near-infrared (UV/vis/NIR) electronic absorption, 57Fe Mössbauer, X-band electron paramagnetic resonance (EPR) and SQUID magnetization measurements. Complex 1 activates dioxygen to yield the diferric, μ-oxo-bridged complex [(OCO)Fe(py)(μ-O)Fe(O(C═O)O)(py)] (2) that was isolated and fully characterized. In 2, one of the iron-carbene bonds was oxidized to give a urea motif, resulting in an O(CNHC═O)O binding site, while the other Fe(OCO) unit remained unchanged. When the reaction is performed at -80 °C, an intensively colored, purple intermediate is observed (INT, λmax = 570 nm; ε = 5600 mol L-1 cm-1). INT acts as a sluggish oxidant, reacting only with easily oxidizable substrates, such as PPh3 or 2-phenylpropionic aldehyde (2-PPA). The identity of INT can be best described as a dinuclear complex containing a closed diamond core motif [(OCO)FeIV(μ-O)2FeIV(OCO)]. This proposal is based on extensive spectroscopic [UV/vis/NIR electronic absorption, 57Fe Mössbauer, X-band EPR, resonance Raman (rRaman), X-ray absorption, and nuclear resonance vibrational (NRVS)] and computational studies. The conversion of the diiron(II) complex 1 to the oxo diiron(IV) intermediate INT is reminiscent of the O2 activation process in soluble methane monooxygenases (sMMO). Most importantly, the low reactivity of INT supports the consensus that the [FeIV(μ-O)2FeIV] diamond core in sMMO is kinetically inert and needs to open up to terminal FeIV═O cores to react with the strong C-H bonds of methane.

Mixed-Valence Iron Complexes Containing End-On Bridging Cyaphide Ions.

Iron cyanide compounds are among the oldest known synthetic coordination compounds, dating back to the early 18th century. By contrast, iron complexes of the cyaphide ion (C≡P-)─a heavy valence isoelectronic analog of the cyanide ion─are unknown. Herein we report the synthesis of highly stable mono- and bis-cyaphide complexes of iron(II), namely Fe(depe)2(Cl)(CP) and Fe(depe)2(CP)2 (depe = 1,2-bis(diethylphosphino)ethane). These iron(II) cyaphide complexes are capable of further coordination to iron(I) in a hitherto unknown linear coordination geometry, affording the conjugated multimetallic mixed-valence complexes [{Fe(depe)2}2(μ-CP)(N2)][BArF4]2 and [{Fe(depe)2}3(μ-CP)2][OTf]2.

Antifungal Activity of Some New Binuclear Complexes

Three complexes of copper(II) and iron(II) with mixed ligands acetylacetonebis(thio-semicarbazone)- ABTSH2 and benzaldazine- BA have been prepared and characterized using different physico-chemical techniques including the determination of metal contents, mole-cular weight, measurement of molar conductivity, magnetic moment, molar refraction, infrared and electronic spectra. Accordingly, octahedral complexes having general formulaes [Cu2(ABTSH2)2(BA)2Cl2]Cl2 and [M2(ABTSH2)2(BA)2(SO4)2] {M= Cu(II) or (Fe(II)} have been proposed. The resulted complexes screened for antifungal activity in vitro against the citrus pathogen Aspergillus niger and Fusarium sp. which caused root rot of sugar and the beans pathogen Alternaria sp. All the complexes exhibited significant antifungal activities against these pathogens. The antifungal activity of these complexes were comparable with the standard fungicides in ethanol. The complex [Cu2(ABTSH2)2(BA)2Cl2]Cl2 had the best antifungal activity against Alternaria sp.

Synthesis, characterization and antimicrobial Studies of complexes of some metal ions with 5(2-hydroxy benzylidine) -2-thio ether -1, 3, 4-thiadiazole

A new series of Fe (III) , Co (II) , Ni (II) and Cu (II) complexes of the Schiff base, 5 (2-hydroxy benzylidine) -2-thio ether -1, 3, 4-thiadiazole were prepared and characterized .The imine behaves as a bidentate. The nature of bonding and the stereochemistry of the complexes were deduced from metal analyses, infrared, electronic spectra,magnetic susceptibility and conductivity measurements, an octahedral geometry was suggested for all complexes except the copper complex has a square planar geometry .preliminary in vitro tests for antimicrobial activity show that all the prepared compounds except iron complex display good activity to gram positive Staphelococcus aures and gram negative Escherchia coli.