Crystal Structure and Spectrum Properties of a Manganese Complex with Schiff Base Ligand，Mn（bzacen）（pyrimidine）（NCS）

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Cyan-Blue Luminescence and Antiferromagnetic Coupling of CN-Bridged Tetranuclear Complex Based on Manganese(III) Schiff Base and Hexacyanoferrate(III)

A new tetranuclear cyanide-bridged Mn^III–Fe^III complex based on manganese(III) Schiff base and hexacyanoferrate(III) units, [Mn(L)(MeOH)₂][{Mn(L)}{Fe(CN)₆}{Mn(L)(MeOH)}].2MeOH, [H₂L?=?N,N′-bis(2-hydroxy-1-naphthalidenato)-1,2-diaminopropane] (1), has been synthesized and characterized by elemental analysis, UV–Vis, FT-IR, PXRD, single crystal X-ray analyses, magnetic and photoluminescence measurements. Complex 1 consist of one trinuclear cyanido-bridged anion, in which [Fe(CN)₆]^3? anion bridge [Mn(L)]⁺ and Mn(L)(MeOH)}]⁺ cations via two C≡N groups in the cis positions, and also one isolated manganese [Mn(L)(MeOH)₂]⁺ cation. DC magnetic susceptibility and magnetization studies showed that complex 1 indicates an antiferromagnetic coupling between low-spin Fe(III) and high-spin Mn(III) through the cyanide bridges. In addition, the complex 1 displays a strong cyan-blue luminescence emission in the solid state condition at room temperature. This behavior might be seen easily from the chromaticity diagram. Thus, the complex may be a good promising cyan-blue OLED developing electroluminescent materials for flatted or curved panel display applications due to the fact that it has such features.     

Antiferromagnetic Coupling in a New Mn(III) Schiff Base Complex with Open-Cubane Core: Structure,Spectroscopic and Luminescence Properties

A new open-cubane Mn^III, [{(H₂O)Mn^IIIL}{Mn^IIIL}]₂·2(CH₃OH).2(CH₃CH₂OH)·2Cl, 1 where H ₂ L=[N-(2-hydroxyethyl)-3-methoxysalicylaldimine] has been synthesized and characterized by element analysis, FT-IR, solid UV–Vis spectroscopy and single crystal X-ray diffraction. The crystal structure determination shows an open-cubane tetranuclear complex. The Mn1 (Mn1ⁱ) ions is hexacoordinate by NO₅ donor sets while the Mn2 (Mn2ⁱ) is pentacoordinate by NO₄ donor sets. The solid state photoluminescence properties of complex 1 and its ligand H ₂ L have been investigated under UV light at 349 nm in the visible region. H ₂ L exhibits blue emission while complex 1 shows orange-red emission at room temperature. Variable-temperature magnetic susceptibility measurements on the complex 1 in the range 2–300 K indicate an antiferromagnetic interaction.     

Synthesis and Crystal Structure of a Salicylaldehyde Ethylene Diamine Schiff Base Manganese (Ⅲ) Complex

1 INTRODUCTION Manganese is one of several first-row transition metal elements that have been found to play an important role in most biological systems. Perhaps the best known is in the process of photosynthesis during which water is oxidized to yield dioxygen, and it is generally believed that the process is related to a tetranuclear manganese cluster[1]. Other aspects of biological chemistry of manganese, such as three mononuclear manganese enzymes: manganese superoxide dismutase, per…     

Versatile Catalytic Applications of Manganese(II,III) Schiff Base Complexes (Review)

Russian Journal of General Chemistry - Manganese forms a big number of complexes with Schiff bases that are extensively used as catalysts of oxidation, epoxidation, decarboxylation, coupling...     

Catalytic Oxidative Decarboxylation of Some Benzylcarboxylic Acid Derivatives by a New Iron(III) Schiff Base Complex

A quadridentate Schiff base ligand of N,N’-bis(2-hydroxy-α-methylbenzylidene)ethylenediamine (HMBEDA) and its new iron(III) complex were synthesized and identified by analytical, spectral data (1H NMR, 13C NMR FT-IR and UV-visible) and molar conductance. A rapid and efficient homogeneous oxidative decarboxylation of some benzylcarboxylic acid derivatives was carried out by a catalytic amount of iron(III) Schiff base complex in chloroform, using tetrabutylammonium periodate as a mild oxidant in good to excellent yields at room temperature.     

Langmuir-Blodgett Films from Schiff Base Aluminium (Ⅲ) Complex

The characteristics of the LB films of Schiff base aluminium(Ⅲ), tris(2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium(Ⅲ)[Al(TA12)_3], were studied. The surface pressure-area(π-A) isotherm of Al(TA12)_3 in the pure water subphase was investigated. The molecular area, 0.48 nm~2, is one-third of the expected value that indicates the formation of an aggregate. The Langmuir-Blodgett(LB) films of Al(TA12)_3 were transferred and characterized. The UV-Vis spectra and the AFM image both confirmed that the J-aggregates formed. The polarized UV-Vis spectra indicated that the complex plane had to be oriented with an angle of about 30° to the substrate surface. The IR spectra suggested that the complexation took place between aluminium ions and the oxygen atoms of the ligand rather than the nitrogen atom.     

Efficient Oxidation of Hantzsch 1,4-Dihydropyridines with Tetrabutylammonium Peroxomonosulfate Catalyzed by Manganese(III) Schiff Base Complexes: The Effect of Schiff Base Complex on the Product Selectivity

Efficient and rapid oxidation of Hantzsch 1,4-dihydropyridine with tetrabutylammonium peroxomonosulfate (TBAO) is reported. The Mn(salophen)/monopersulfate catalytic system efficiently converts 1,4-dihydropyridines (DHPs) to their corresponding pyridine derivatives under mechanical stirring and microwave irradiation in CH₂Cl₂. The ability of various Schiff base complexes to oxidize DHPs was also investigated. The results showed that in the presence of manganese Schiff complex, no by-product was obtained.     

三核锰配合物[Mn3O(O2CCH=CHCH3)6(py)3]ClO4·py的合成,晶体结构及磁性

The reaction of N-n-Bu4MnO4 with Mn(Oac) 2 · 4H2O and butenoic acid in nonaqueous solvents leads to the formation of the complex [Mn3O(O2CCH = CHCH3) 6(py) 3] ClO4 · py (1). The crystal structure was determined.The complex crystallizes in hexagonal, space group P63/m, unit cell parameters, a = 1. 2456(1)nm, b = 1. 2456(1) nm, c = 1. 8741(1) nm, V=2. 5181(3) nm3, Z =2, and final R1 =0. 0565, wR2 =0. 1465. Variable tem-perature solid tate magnetic susceptibility study shows that the complex [Mn3O(O2CCH = CHCH3)6(py)3] ClO4 (2) has an antiferromagnetic exchange interaction.     

PNPP Hydrolysis Catalyzed by Manganese(III) Complexes with Crowned Salicylaldimine Schiff Base Ligand

Four manganese(III) complexes (MnL¹Cl, MnL²Cl, MnL⁴₂Cl, MnL⁵₂Cl) with a crowned salicylaldimine Schiff base ligand have been synthesized and employed as models to mimic hydrolase in the hydrolysis of p-nitrophenyl picolinate (PNPP). The kinetics and mechanism of catalytic PNPP hydrolysis have been investigated. The kinetic mathematical model of PNPP cleavage catalyzed by these complexes has been proposed. The effects of the ligand structure and crown ether ring in complexes, and the reactive temperature on the rate of catalytic PNPP hydrolysis have been also examined. The results show that compared with the crown-free analogous MnL³Cl and MnL⁶₂Cl, the crowned Schiff base manganese(III) complexes, MnL¹Cl, MnL²Cl, MnL⁴₂Cl and MnL⁵₂Cl, exhibit more high catalytic activity, which follow the order: MnL¹Cl >MnL²Cl >MnL⁴₂Cl >MnL⁵₂Cl >MnL³Cl >MnL⁶₂Cl; the pseudo-first-order-rate (k_obs) for the PNPP hydrolysis catalyzed by the complex MnL¹Cl containing three crown ether rings is highest among six complexes and is 1.81 times that of MnL³Cl, 1.49 × 10³ times that of spontaneous hydrolysis of PNPP, respectively, at pH = 7.00, [S] = 2.0 × 10⁻⁴ mol dm⁻³.     

混合价双核锰[Mn2(cyclen)2(μ-O)2](ClO4)3·4H2O的晶体结构和表征

The mixed-valence manganese(Ⅲ/Ⅳ) complex [Mn2(cyclen)2(μ-O)2](ClO4)3-4H2O (1) (cyclen=1,4,7,10-tetraazacyclododecan) with chemical formula C16H48Cl3Mn2N8O18 has been synthesized and characterized by single crystal X-ray diffraction analysis, elemental analysis, IR and electronic spectra. The results showed that the manganese(Ⅲ/Ⅳ) ions were six-coordinated by four nitrogen atoms from cyclen and two oxygen atoms from the oxygen bridge, forming a distorted octahedron geometry. There were two very strong peaks in the range of 400-700 nm in electronic spectrum, which was similar to Mn catalase and Mn ribonucleotide reductase extracted from organisms.Electrochemical study indicated that the complex underwent a quasi-reversible one-electron reduction and oxidation at E1/2=0.827 V in acetonitrile.     

Solvent Effects on the Electrochemical Behavior of Iron(III) Schiff Base Complex

Electrochemical reduction of Fe^IIILCl where L is a Schiff base has been investigated in various aprotic solvents. From a plot of the half wave potential E _1/2 for the reduction of these complexes vs. E _1/2 for the oxidation of ferrocene, the solvent–solute interactions were studied: the E _1/2 variation is found to be a function of Lewis-type acceptor–donor interactions. The diffusion coefficients D in the different solvents were also been determined by linear sweep voltammetry. The variation of D is discussed in terms of viscosity and dielectric constant.     

Studies on the Phenol Oxidation with H2O2 Catalyzed by Metallomicelle Made from Crowned Schiff Base Mn(III) Complexes

Metallomicelles made from two Schiff base manganese(III) complexes (MnL¹ and MnL²) and surfactants (CTAB and Brij35) were used as mimetic peroxidase in the catalytic oxidation of phenol by H₂O₂. The catalytic activity of the complexes (MnL¹ and MnL²) were investigated. The mechanism and a kinetic mathematic model of the phenol catalytic oxidation were also studied. The results show the optimum acidity of the enzyme-like system in the paper is ca. pH 7.0, the optimum temperature which is ca. 35°C and the optimum molar ratio of H₂O₂ to the complex is ca. 30 in the complexes-H₂O₂-buffered solution; the Schiff base manganese(III) complexes and their metallomicelles as peroxidase mimics exhibit good catalytic activity and similar catalytic character to natural enzyme.     

Manganese(III) complexes with tetradentate (N2O2) Schiff bases and dicyanamide

New Mn(III) complexes with Schiff bases and dicyanamide are synthesized: [Mn(Salpn)N(CN)₂] _n (two polymorphous modifications, Ia and Ib), {[Mn(5-BrSalen)N(CN)₂] · CH₃OH} _n (II), and [Mn(3-MeOSalen)N(CN)₂(H₂O)] (III), where SalpnH₂ = N,N′-bis(salicylidene)-1,3-diaminopropane, 5-BrSalenH₂ = N,N′-bis(5-bromosalicylidene)-1,2-diaminoethane, and 3-MeOSalenH₂ = N,N′-bis(3-methoxysalicylidene)-1,2-diaminoethane. Complexes Ia, Ib, and II have the polymer structure in which the dicyanamide anion binds the paramagnetic Mn(III) complexes with the Schiff bases into one-dimensional chains. Unlike them, in complex III the monomer units containing water and the dicyanamide anion as terminal ligands form dimers due to hydrogen bonds. The study of the magnetic properties of complexes Ia and II shows a weak antiferromagnetic interaction between the Mn³⁺ ions through the dicyanamide bridges in these complexes.     

Evidence of a Photo‐Radical Pathway Responsible of the Rearrangement of a Manganese(III)‐Schiff Base Complex in Solution

A new Mn^III‐Schiff base complex, [MnL(OH₂)](ClO₄) ( 1 ) (H₂L = N, N′‐bis‐(3‐Br‐5‐Cl‐salicylidene)‐1, 2‐diimino‐2‐methylethane), an inorganic model of the catalytic center (OEC, Oxygen Evolving Complex) in photosystem II (PSII), has been synthesized and characterized by elemental analysis, IR and EPR spectroscopy, mass spectrometry, magnetic susceptibility measurement and the study of its redox properties by cyclic and normal pulse voltammetry. This complex mimics reactivity (showing a relevant photolytic activity), and also some structural characteristics (parallel‐mode Mn^III EPR signal from partially assembled OEC cluster) of the natural OEC. The complex 1 was found to rearrange in solution into a crystallographically solved square‐pyramidal complex, [MnLL′] ( 2 ) (HL′ = 6‐bromo‐4‐chloro‐2‐cyanophenol), through a process, which probably liberates radical species (detected by EPR), and provokes a C—N bond cleavage in the ligand. A photo‐radical mechanism is discussed to explain this rearrangement.     

Asymmetric Schiff Base (N 2 O 3 ) Complexes as Ligands Towards Mn(II), Fe(III) and Co(II), Synthesis and Characterization

Heterobi- and tri-nuclear complexes [LMM'Cl] and [(LM) 2 M'](M=Ni or Cu and M'=Mn, Fe or Co) have been synthesised. The heteronuclear complexes were prepared by stepwise reactions using two mononuclear Ni(II) and Cu(II) complexes of the general formula [HLM]·1/2H 2 O, as ligands towards the metal ions, Mn(II), Fe(III) and Co(II). The asymmetrical pentadentate (N 2 O 3 ) Schiff-base ligands used were prepared by condensing acetoacetylphenol and ethylenediamine, molar ratio 1 1, to yield a half-unit compound which was further condensed with either salicylaldehyde or naphthaldehyde to yield the ligands H 3 L 1 and H 3 L 2 which possess two dissimilar coordination sites, an inner four-coordinate N 2 O 2 donor set and an outer three-coordinated O 2 O set. 1 H NMR and IR spectra indicate that the Ni(II) and Cu(II) ions are bonded to the inner N 2 O 2 sites of the ligands leaving their outer O 2 O sites vacant for further coordination. Different types of products were obtained according to the type of metal ion. These products differ in stoichiometry according to the type of ligand in the parent compound. Electronic spectra and magnetic moments indicate that the structures of the parent Ni(II) and Cu(II) complexes are square-planar while the geometry around Fe(III), Mn(II) and Co(II) in their products are octahedral as elucidated from IR, UV-visible, ESR, 1 H NMR, mass spectrometry and magnetic moments.     

一个锰(Ⅲ)Schiff碱配合物[Mn(napn)(CH_3OH)_2]ClO_4的合成与晶体结构

合成了一个新配合物[Mn(napn)(CH3OH)2]ClO4 (C26H26 Cl N2O8Mn,Mr = 584.88,H2napn = 双a-萘酚醛缩乙二胺),并测定了其晶体结构。晶体属于三斜晶系,空间群P ,a = 7.813(1),b = 13.025(2),c = 14.089(2) ? = 64.89(3), = 83.98(3), = 78.11(3)海琕 = 1270.16 ?,Z = 2, Dc = 1.529 g/cm3, F(000) = 604, R = 0.0837, wR = 0.1636。锰(Ⅲ)离子的配位构型为拉长的八面体。Schiff碱配体napn2-中的N2O2在赤道平面与锰(Ⅲ)形成四配位,2个CH3OH中的O原子分别在赤道平面两侧轴向位置与锰(Ⅲ)配位。由于Jahn-Teller效应,轴向上的MnO平均键长为2.52 拧A硗猓О写嬖诜肿幽诤头肿蛹淝饧?