Dinuclear Manganese Complex Research Articles

Design and synthesis of new water-soluble dinuclear manganese(II) complexes as monosaccharide binding models

The present article describes the design, synthesis, physicochemical characterization and monosaccharide binding events of two new water-soluble dinuclear manganese(II) complexes [Mn2(phpda)(µ-Cl)]·2H2O (1) and [Mn2(phpda)(µ-OAc)]·2H2O (2) of carboxylate and pyridyl-functionalized multidentate ligand, H3phpda (H3phpda = N,N′-bis[2-pyridylmethyl]-2-hydroxy-1,3-propanediamine-N,N′-dipropionic acid). FTIR, UV–Vis, ESI-MS, microanalysis, molar conductivity, cyclic voltammetry and room-temperature magnetic data establish their compositions. Structural features of 1 and 2 obtained from theoretical calculations indicate a self-assembled and well-packed array with average Mn···Mn separation of 2.952 Å. Both 1 and 2 have been studied towards 1:1 binding interactions with biologically important monosaccharides, such as d-glucose, d-xylose and d-glucosamine by employing UV–Vis spectroscopy and DFT computation. The binding constant values of monosaccharide-bound manganese(II) complexes evaluated from UV–Vis titration data are 2.145 x 103 M−1, 2.156 x 103 M−1, 2.652 x 103 M−1, 1.388 x 103 M−1, 1.793 x 103 M−1 and 2.146 x 103 M−1 for 1/d-glucose, 1/d-xylose, 1/d-glucosamine, 2/d-glucose, 2/d-xylose and 2/d-glucosamine assemblies, respectively. The possible metal centers engaged in the binding events have been ascertained by calculating the Fukui functions (fk+) on the manganese sites, including HOMOs and LUMOs. A comparative assessment of sugar-binding properties, in particular, suggests that the order of binding ability of monosaccharides with 1 and 2 is found to be d-glucosamine > d-xylose > d-glucose.

Trinuclear manganese and zinc clusters and a dinuclear manganese complex with multiple oxo-bridges: Syntheses, structures, and magnetic properties of the MnII compounds and luminescent property of the ZnII complex

Two trinuclear clusters [Mn3(L1)2] (1) and [Zn3(L1)2] (2) have been prepared from the reactions of Mn(CH3COO)2·4H2O and Zn(CH3COO)2·4H2O, respectively, with a hydroxy-rich Schiff-base ligand H3L1 (H3L1 = 2-{[bis(2-hydroxy-3-methoxybenzyl)(amino-ethyl)amino]methyl}phenol). One dinuclear compound [Mn2(HL2)Cl2] (3) was synthesized from the treatment of MnCl2·4H2O with another hydroxy-rich Schiff base ligand H3L2 (H3L2 = 2-{[bis(2-hydroxy-3-methoxybenzyl)(amino-ethyl)amino]ethyl}phenol). Complexes 1–3 were characterized by single-crystal X-ray diffraction analysis. The structural analyses indicated that complexes 1 and 2 are isostructural and contain linear MnII–MnII–MnII and ZnII–ZnII–ZnII cores. In compounds 1–3, the metal centers are doubly bridged by phenoxido groups of the ligands. Variable temperature magnetic measurements of 1 and 3 revealed the presence of antiferromagnetic intramolecular couplings, and the magnetic susceptibility data are consistent with S = 5/2 of the MnII ions. The luminescent property of compound 2 was investigated. The 3d10 zinc compound 2 exhibited strong luminescence with λmax = 491 nm (for λex = 418 nm).

Mechanistic Insights into Superoxide Dismutation Driven by Dinuclear Manganese Complexes: The Role of the Mn2-Core

The dinuclear Mn2(II,II)L2-core (HL = 2-{[[di(2-pyridyl)methyl](methyl)amino]-methyl}phenol) has been recently reported to be the most active dual superoxide dismutase (SOD) and catalase (CAT) functional analogue, enabling cascade detoxification of the superoxide radical anion. Here, we investigated the mechanism of catalytic O2•– decomposition by two stereoisomers with the Mn2(II,II)L2-core, Mn2L2Ac and Mn2L2, in order to (i) precisely determine the catalytic SOD activity of the complexes, (ii) characterize the key intermediates involved in the dismutation process, and (iii) discriminate between single- and di-Mn center catalysis in relation to the configuration of the Mn2-core. The conclusions drawn from low-temperature mass spectrometry, stopped-flow kinetics, cyclic voltammetry, water exchange 17O nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) analyses were supported by the structural characterization and quantum chemical analysis of the proposed reaction intermediates. This study allows us to determine kcat for Mn2L2Ac and Mn2L2 (4.6 × 107 and 2.2 × 107 M–1 s–1, respectively, in 3-(N-morpholino)propanesulfonic acid (MOPS) at pH = 7.4) and detect the key intermediates involved in the catalytic cycle driven by these Mn2-SOD mimics, highlighting the formation of a side-on η2–Mn2(III,II)–peroxo, as an initial intermediate. The effects of the Mn2(II,II)-core configuration on the SOD activity were discussed.

Water Oxidation by a Neoteric Dinuclear Mn(II) Electrocatalyst in Aqueous Medium

AbstractThe employment of manganese complexes towards electrocatalytic water oxidation has gained immense interest among the scientific communities. In this present study, the reaction of Mn(CH3COO)2⋅4H2O with the novel ligand (2‐([2,2′:6′,2“‐terpyridin]‐4′‐yl)quinoline‐8‐ol) (8hq‐tpy) affords a dinuclear manganese complex, [MnII(8hq‐tpy)(H2O)]2(PF6)2 (Mn 1). Various spectroscopic techniques have been implemented for characterization purposes, and Mn 1 is employed as electrocatalysts towards water oxidation catalysis in the aqueous medium. Electrocatalytic responses in the aqueous medium at pH 6.0 lead to the electrodeposition of heterogeneous species (MnOX) which enables the oxidation event at an applied potential of 1.24 V vs. NHE with O2 liberation of 50.2 μmol/L. The XPS analysis performed after executing bulk electrolysis, provide evidence for the generation of MnIV=O as the active species formed by the catalyst precursor complex Mn 1, contributing to O2 evolution during the electrocatalytic water oxidation process.

A new phenolato-bridged dinuclear manganese(II) complex as a turn-on fluorosensor for Zn2+ ions via Mn2+ ion replacement

A new synthesized and structurally characterized phenolato bridged di-nuclear manganese(II) complex, formulated as [Mn2L(OAc)2(DMF)2]PF6 (1) (where HL = 4-methyl-2,6-bis-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol and OAc = acetate anion), can act as a turn-on Zn2+ sensing probe through the in situ formation of the corresponding dinuclear Zn(II) complex, [Zn2L(OAc)2]PF6 (2) via direct Mn2+ ion replacement in MeOH/DMF (1/14) medium. The selective and specific fluorescent change due to addition of Zn2+ ions to a solution of 1 enables the detection of Zn2+ ions in dimethylformamide (DMF). The fluorescent dinuclear zinc(II) complex 2 has also been produced through the direct reaction between Zn2+ ions and HL. Both complexes 1 and 2 have been characterized by using physico-chemical and spectroscopic tools, and finally by single crystal X-ray crystallography for a detailed structural determination. The crystallographic investigation indicates that the Mn(II) and Zn(II) ions in the complexes exhibit a distorted octahedral and distorted trigonal bipyramidal coordination geometry, respectively. Interestingly, complex 1 showed very weak fluorescence in solution and no emission in the solid state, whereas complex 2 gave a strong bluish-green coloured fluorescence in both solution and in the solid state, which may be due to the distinct packing of complex 2 compared to 1, as well as to intermolecular hydrogen bonding and CH---π, CH---N and CH---O interactions in the crystal packing, likely playing crucial roles for the fluorescence behavior.

Crystal Structure of a μ-Phenolato-μ-oxido-bridged Dinuclear Manganese(III) Complex with Dinucleating Schiff-base Ligand Having Three Phenolate Groups

Crystal Structure of a μ-Phenolato-μ-oxido-bridged Dinuclear Manganese(III) Complex with Dinucleating Schiff-base Ligand Having Three Phenolate Groups

A New Phenolato-Bridged Dinuclear Manganese(II) Complex as a Turn-On Fluorosensor for Zn <sup>2</sup>+ Ions Via Mn <sup>2</sup>+ Ion Replacement

A new synthesized and structurally characterized phenolato bridged di-nuclear manganese(II) complex, formulated as [Mn2L(OAc)2(DMF)2]PF6 (1) (where HL = 4-methyl-2,6-bis-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol, and OAc = acetate anion) can act as a turn-on Zn2+ sensing probe through in situ formation of the correspondent dinuclear Zn(II) complex, [Zn2L(OAc)2]PF6 (2) via direct Mn2+ ion replacement in in MeOH/DMF (1/14) medium. This selective and specific fluorescent change due to addition of Zn2+ ions to the solution of 1 enables to detect Zn2+ ion in dimethylformamide (DMF). The fluorescent dinuclear zinc(II) complex 2 has been achieved also through the direct reaction between Zn2+ ions and HL. Both the complexes 1 and 2 have been characterized using physico-chemical and spectroscopic tools, and finally by single crystal X-ray crystallography for a detailed structural determination. The crystallographic investigation indicates that the Mn(II) and Zn(II) in the complexes exhibit a distorted octahedral and distorted trigonal bipyramidal coordination geometry, respectively. Interestingly, complex 1 showed a very weak fluorescence in solution and no emission in solid state, whereas complex 2 gave a strong bluish-green coloured fluorescence in both solution and solid state, which may be due to the distinct packing of complex 2 compared to 1, as well as to the intermolecular hydrogen bonding and C–H---π, C–H---N, C–H---O interactions in the crystal packing, likely playing crucial roles for the fluorescence behavior.

Model Dimeric Manganese(IV) Complexes Featuring Terminal Tris-hydroxotetraazaadamantane and Various Bridging Ligands.

A series of model dinuclear manganese(IV) complexes of the general formula [(H3COH)(L')MnIV(μ-L)2MnIV(L')(HOCH3)] is presented. These compounds feature capping 4,6,10-trihydroxo-3,5,7-trimethyl-1,4,6,10-tetraazaadamantane ligands derived from a polydentate oxime compound (L'). The bridging ligands L include azide (1), methoxide (2), and oxalate (3) anions. The magnetic properties and high-field (HF) EPR spectra of 1-3 were studied in detail and revealed varying weak antiferromagnetic coupling and modest zero-field splitting (ZFS) of the local quartet spin sites. Our HF EPR studies provide insight into the dimer ZFS, including determination of the corresponding parameters by giant spin approach for methoxido-bridged complex 2. Furthermore, the physicochemical properties of 1-3 were studied using IR, UV-vis, and electrochemical (cyclic voltammetry) methods. Theoretical exchange coupling constants were obtained using broken-symmetry (BS) density functional theory (DFT). Computational estimates of the local quartet ground spins state ZFSs of 1-3 were obtained using coupled-perturbed (CP) DFT and complete active space self-consistent field (CASSCF) calculations with n-electron valence state perturbation theory (NEVPT2) corrections. We found that the CP DFT calculations which used the B3LYP functional and models derived experimental structures performed best in reproducing both the magnitude and the sign of the experimental D values. Moreover, our computational investigation of 1-3 suggests that we observe metals sites which have an increased +3 character and are supported by redox noninnocent 4,6,10-trihydroxo-3,5,7-trimethyl-1,4,6,10-tetraazaadamantane ligands. The latter conclusion is further corroborated by the observation that the free ligand can be readily oxidized to yield a NO-based radical.

Conversion of (µ-OH)2Mn2(II,II) complex to (µ-O)2Mn2(III,III) core supported by a quinoxaline-based tetranitrogen ligand

Quinoxaline-based tetranitrogen ligand, N,N’-bis(2-quinoxalylmethyl)-N,N’-dimethylethylenediamine (L9), stabilizes the bis(µ-hydroxo) dinuclear manganese(II,II) core. Oxidation of the complex with hydrogen peroxide in methanol suspension affords the bis(µ-oxo) dinuclear manganese(III,III) complex. The quinoxaline-based tripod ligand, tris(2-quinoxalylmethyl)amine (L11), did not afford corresponding bis(hydroxo) dimanganese(II,II) complex due to the subsequent atmospheric oxygen-promoted oxidation in the reaction solution similar to its quinoline counterpart, tris(2-quinolylmethyl)amine (L10). The solid state structures of [Mn(II)Cl2(L9)], [(µ-OH)2Mn2(II,II)(L9)2]2+, [(µ-O)2Mn2(III,III)(L9)2]2+, [(µ-O)2Mn2(III,III)(L11)2]2+, and [(µ-O)2Mn2(III,III)(L10)2]2+ complexes were determined by X-ray crystallography. The magnetic susceptibility measurement of (µ-OH)2Mn2(II,II) complex and electrochemical oxidation of (µ-O)2Mn2(III,III) complexes were performed to evaluate the tetramine ligand effect stabilizing the low oxidation states of dinuclear metal center supported by two oxygen atom bridges.

Assessment of Double-Hybrid Density Functional Theory for Magnetic Exchange Coupling in Manganese Complexes

Molecular systems containing magnetically interacting (exchange-coupled) manganese ions are important in catalysis, biomimetic chemistry, and molecular magnetism. The reliable prediction of exchange coupling constants with quantum chemical methods is key for tracing the relationships between structure and magnetic properties in these systems. Density functional theory (DFT) in the broken-symmetry approach has been employed extensively for this purpose and hybrid functionals with moderate levels of Hartree–Fock exchange admixture have often been shown to perform adequately. Double-hybrid density functionals that introduce a second-order perturbational contribution to the Kohn–Sham energy are generally regarded as a superior approach for most molecular properties, but their performance remains unexplored for exchange-coupled manganese systems. An assessment of various double-hybrid functionals for the prediction of exchange coupling constants is presented here using a set of experimentally characterized dinuclear manganese complexes that cover a wide range of exchange coupling situations. Double-hybrid functionals perform more uniformly compared to conventional DFT methods, but they fail to deliver improved accuracy or reliability in the prediction of exchange coupling constants. Reparametrized double-hybrid density functionals (DHDFs) perform no better, and most often worse, than the original B2-PLYP double-hybrid method. All DHDFs are surpassed by the hybrid-meta-generalized gradient approximation (GGA) TPSSh functional. Possible directions for future methodological developments are discussed.

Tetra- and dinuclear manganese complexes of xanthene-bridged O,N,O-Schiff bases with 3-hydroxypropyl or 2-hydroxybenzyl groups: ligand substitution at a triply bridging site

Complexation properties of U-shaped ligands, L1 and L2, which are Schiff bases of 5,5'-(9,9-dimethylxanthene-4,5-diyl)bis(salicylaldehyde) (H2xansal) with 3-amino-1-propanol or 2-hydroxybenzylamine, respectively, were investigated to construct polynuclear manganese complexes. In these ligands, two O,N,O-Schiff bases are bridged by a xanthene backbone. The reactions of H4L1 or H4L2 with manganese salts afforded tetra- and dinuclear manganese complexes, including the tetramanganese(ii,ii,iii,iii) complex [Mn4(L1)2(μ-OAc)2] with a Mn4O6 core exhibiting an incomplete double-cubane structure. In the Mn4O6 core, phenolate and alkoxide O atoms bridge the manganese ions. Deprotonated 3-hydroxypropyl groups were crucial to the assembly of four manganese ions because the phenolate-bridged dimanganese(iii,iii) complex [Mn2(H2L1)2]2+ was obtained in the absence of a base, and H4L2, which has 2-hydroxybenzyl groups instead of 3-hydroxypropyl groups in H4L1, afforded the cyclic dimanganese(iv,iv) complex [Mn2(L2)2]. We disclosed that [Mn4(L1)2(μ-OAc)2] was converted to the oxo-bridged tetramanganese(iii,iii,iii,iii) complex [Mn4(L1)(HL1)(μ3-O)(μ-OAc)2]+ by treating with NH4PF6 or NH4BF4: a triply bridging alkoxide was protonated and replaced by an oxide ligand. The cyclic voltammograms of [Mn4(L1)(HL1)(μ3-O)(μ-OAc)2]+ suggested that the reverse reaction forming [Mn4(L1)2(μ-OAc)2] occurred in the electrochemical processes and was assisted by protonation.

Dinuclear manganese(iii) complexes with bioinspired coordination and variable linkers showing weak exchange effects: a synthetic, structural, spectroscopic and computation study.

Three dimanganese(iii) complexes have been synthesised and fully characterised by standard spectroscopic methods and spectroelectrochemistry. Each MnIII ion is chelated by a salen type ligand (H2L), but there is variation in the bridging group: LMn(OOCCH[double bond, length as m-dash]CHCOO)MnL, LMn(OOCC6H4COO)MnL, and LMn(OOCC6H4C6H4COO)MnL. X-ray diffraction revealed an axial compression of each six-coordinate high-spin d4 MnIII ion, which is a Jahn-Teller-active ion. Temperature dependent magnetic susceptibility and variable temperature-variable field (VTVH) magnetisation measurements, as well as high-frequency and -field EPR (HFEPR) spectroscopy were used to accurately describe the magnetic properties of the complexes, not only the single-ion spin Hamiltonian parameters: g-values and zero-field splitting (ZFS) parameters D and E, but also the exchange interaction constant J between the two ions, which has been seldom determined for a di-MnIII complex, particularly when there is more than a single bridging atom. Quantum chemical calculations reproduced well the electronic and geometric structure of these unusual complexes, and, in particular, their electronic absorption spectra along with the spin Hamiltonian and exchange parameters.

Dinuclear manganese alkoxide complexes as catalysts for C-N bond cleavage of simple tertiary N,N-dialkylamides to give esters.

Amide bonds are stable due to the resonance between the nitrogen lone pair and the carbonyl moiety, and therefore the chemical transformation of amides, especially tertiary amides, involving C-N bond fission is considered one of the most difficult organic reactions, unavoidably requiring harsh reaction conditions and strong acids or bases. We report the catalytic C-N bond cleavage of simple tertiary N,N-dialkylamides to give corresponding esters using a catalyst system (2 mol% based on Mn atoms) of a tetranuclear manganese alkoxide, [Mn(acac)(OEt)(EtOH)]4 (1c), combined with four equivalents of 4,7-bis(dimethylamino)-1,10-phenanthroline (L1: Me2N-Phen). Regarding the reaction mechanism, we isolated a dinuclear manganese complex, [Mn(acac)(OEt)(Phen)]2 (6c), which was revealed as the catalytically active species for the esterification of tertiary amides.

Non-redox metal ions accelerated oxygen atom transfer by Mn-Me3tacn complex with H2O2 as oxygen resource

This work demonstrates a novel strategy that the introduction of non-redox metal ions as Lewis acids to the classic dinuclear manganese complex [MnIV2(μ-O)3(Me3tacn)2](PF6)2 can greatly promote the alkene epoxidation efficiency under mild conditions with H2O2 as the solely terminal oxidant because of its economic and environmental advantages. When [MnIV2(μ-O)3(Me3tacn)2](PF6)2 was used as the catalyst in the absence of Lewis acids, only 16.4% conversion of cyclooctene with 6.2% yield of epoxide was obtained and the obvious decomposition of H2O2 was observed. However, the oxygen transfer efficiency of the catalyst was sharply improved with 100% conversion and 90.2% yield of epoxide under identical conditions when the non-redox metal ion, such as Sc3+, was introduced to the catalytic system. The novel strategy was successfully applied to the epoxidation reactions of different types of alkenes. Through UV–vis, FT-IR, EPR and CV characterizations, it was evidenced that the non-redox metal ions with high positive charge as Lewis acids could dissociate the sluggish dinuclear Mn-(μ-O)3-Mn core and the open-loop dinuclear manganese complex, HO-MnIII-(μ-O)-MnIV = O or O = MnIV-(μ-O)-MnIV = O, was proposed as the active species, which was capable of the alkene epoxidation process. This work illustrated an alternative protocol to manipulate the reactivity of those sluggish catalysts by the introduction of non-redox metal ions and provided clues to understand the role of non-redox metal ions in metalloenzymes and heterogeneous catalysts.

Synthesis, Crystal Structures, and Catalytic Properties of Dinuclear Manganese(III) Complexes Derived from N,N′-Bis(5-Methylsalicylidene)propane-1,2-Diamine

Two centrosymmetric dinuclear manganese(III) complexes, [Mn2L2(N3)2] (I) and [Mn2L2(NCS)2] (II), where L is the deprotonated form of N,N'-bis(5-methylsalicylidene)propane-1,2- diamine (H2L), have been prepared and structurally characterized by elemental analysis, IR and UV-Vis spectra and single crystal X-ray diffraction (СIF files CCDC nos. 1553014 (I), 1553015 (II)). The Mn atoms are in octahedral coordination. Catalytic properties for epoxidation of styrene by the complexes using PhIO and NaOCl as oxidant have been studied.

Toward an automated analysis of exchange pathways in spin-coupled systems.

Understanding (super-)exchange coupling between local spins is an important task in theoretical chemistry and solid-state physics. We show that a Green's-function approach introduced earlier (Liechtenstein et al., J. Phys. F 1984, 14, L125; Steenbock et al., J. Chem. Theory Comput. 2015, 11, 5651) can be used for analyzing exchange coupling pathways in an automated fashion rather than by visual inspection of molecular orbitals. We demonstrate the capabilities of this approach by comparing it to previously published pathway analyses for hydroxy-bridged dinuclear copper complexes and an oxo-bridged dinuclear manganese complex, and employ it for discriminating between through-space and through-bond pathways in a naphthalene-bridged bisnickelocene complex. © 2017 Wiley Periodicals, Inc.

Synthesis and structural characterization of a new high-valent bis(oxo)-bridged manganese(IV) complex and its catechol oxidase activity

The work in this report presents the synthesis, structural and spectroscopic characterization of a new type of high-valent bis(oxo)-bridged dimanganese(IV) complex 1 supported by a pyridine and phenol based tetradentate flexible N3O donor HL ligand (where HL=2-benzyl-6-((bis(pyridin-2-ylmethyl)amino)methyl)-4-chlorophenol). Complex 1 possess unique Mn2(μ-O)2 core with short Mn⋯Mn distances (2.65Å) and Mn–O distance (1.80Å). This dinuclear manganese(IV) complex show excellent catecholase-like activity for the aerobic oxidation of 3,5-di-tert-butylcatechol to the corresponding o-quinone in acetonitrile at 25°C. Kinetic measurements suggest that the rate of catechol oxidation follows saturation kinetics with respect to the substrate and first order kinetics with respect to the catalyst.

Synthesis, crystal structure, and antimicrobial activity of a novel chlorido-bridged dinuclear manganese(III) complex derived from N,N′-bis(5-methylsalicylidene)diethylenetriamine

ABSTRACTA novel chlorido-bridged dinuclear manganese(III) complex, [Mn2L2(μ-Cl)Cl2)]·Cl·0.5CH3OH, where L is the zwitterionic form of N,N’-bis(5-methylsalicylidene)diethylenetriamine, has been prepared and characterized by elemental analyses, IR, and single-crystal X-ray crystallographic determination. The crystal of the complex is monoclinic: space group C2/c, a = 20.0300(9), b = 22.8494(8), c = 22.127(1) Å, β = 112.882(3)°, V = 9330.0(7) Å3, Z = 8. The asymmetric unit of the compound contains two dinuclear manganese complex cations, two chloride anions, and one methanol solvate. The Schiff base ligand coordinates to two Mn atoms through the phenolate O and imine N atoms, with the amine N atom protonated. The effect of the complex on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans was studied.

Synthesis and magnetic properties of a dinuclear manganese(II) complex with two manganese(II) ions of C2-twisted octahedral geometry

A dinuclar manganese(II) complex [Mn2(sym-hcp)2](BPh4)2·2acetone·2H2O (1) was synthesized with a new dinucleating ligand, 4-chloro-2,6-bis[(2-hydroxyethyl)methylaminomethyl]phenol [H(sym-hcp)], for the purpose of studying the magnetic properties. The single-crystal X-ray analysis revealed a bis-μ-phenolato-dimanganese(II) core structure containing two distorted octahedral manganese(II) ions of C2 symmetry. The order of the coordination bond lengths is Mn–O(phenolato)<Mn–O(hydroxy)<Mn–N. Magnetic susceptibility data for 1 was fitted well with the parameters 2J=−0.93cm−1 and g=2.03, indicating weak antiferromagnetic interaction.

A mononuclear nickel(II) complex and a dinuclear manganese(III) complex derived from N,N'-bis(5-methoxysalicylidene)-1,2-ethanediamine: Synthesis, crystal structures and catalytic epoxidation property

Synthesis and characterization of a mononuclear nickel(II) complex [NiL] · CH3OH (I) and a dinuclear manganese(III) complex [Mn2L2(NCS)2] (II) derived from the bis-Schiff base N,N'-bis(5-methoxysalicylidene)-1,2-ethanediamine (H2L) are reported. The complexes were characterized by elemental analyses, IR spectra and molar conductivity. Single crystal X-ray structures of the complexes have been determined (CIF files CCDC nos. 1056778 (I) and 1056688 (II)). The Ni atom in I is in a square planar coordination, and the Mn atom in II is in an octahedral coordination. Catalytic property for epoxidation of styrene by the complexes using PhIO and NaOCl as oxidant has been studied. As a result, complex II is efficient for the styrene epoxidation.