Crystal Structure of cis-Dichlorobis-(1,10-phenanthroline) Manganese(Ⅱ)

1INTRODUCTIONRecently,considerableattentionhasbeenpaidtotheinvestigationofcoordinationchemistryofmanganeseindifferentoxidationstatesnotonlybecauseofthediscoveryoftightlyboundmanganeseatomsinvariousbiomolecules[libutalsobecauseoftheirinterestingstructural,magneticandspectroscopicfeatures.Wehavepreparedseveralcomplexesofmanganese(n)withdifferentligands.Thestructuresandfeaturesofthesecompoundsarestudiedsystematically.Inthispaperwedescribethestructureofthecomplexwiththeligandsofphenanthroline…     

Synthesis and Crystal Structure of a New Dinuclear Manganese(Ⅱ) Manganese(Ⅲ) Complex of a Macrocyclic Ligand

A mixed-valence dinuclear manganese complex, [MnⅡMnⅢL](ClO4)·1/2MeOH, where L is a macrocyclic ligand derived from the cyclocondensation of sodium 2,6-diformyl-4-methylphenolate with N,N-bis(2-aminoethyl)-2-hydroxybenzyl amine, was obtained and its structure was determined by X-ray diffraction. The orange crystal is a monoclinic system with space group P21/c and lattice parameters a=1.1617(4), b=1.4005(3), c=1.4641(3) nm, β=113.03(2)°, and Z=2. The crystal structure shows that each pendant-arm is bonded in a bidentate fashion to the adjacent metal atom and that both the arms are on the same side of the macrocycle. The two Mn atoms are bridged by two μ2-phenoxy oxygen atoms of the tetra-imine macrocycle, and each Mn atom, locating in a trigonal prismatic coordination environment(N3O3), is six-coordinated by the two imine nitrogen atoms, one tertiary nitrogen atom and a pendant phenol moiety apart from the two oxygen atoms.     

Synthesis and Crystal Structure of BIS(Imidazole)(µ-Succinato) Manganese(II)

The title complex was prepared by reaction of succinatomanganese(II) with imidazole in water-ethanol. The complex crystallizes in orthorhombic space group Pna 2 1 with a = 7.9990(15), b = 14.8690(15), c = 11.028(2) Å. The metal assumes a distorted octahedral coordination. In the crystal, each succinate dianion bridges three Mn(II) atoms to form a polymer with a layered structure.     

Crystal Structure and Catalytic Properties of Tetrakis (4-hydroxyphenyl) Porphyrinato Manganese(Ⅲ) Chloride (MnTHPPCl)

The crystal structure of meso-tetrakis(4-hydroxyphenyl)porphyrinato manganese chloride(MnTHPPCl)and its supramolecular architecture based on the hydrogen bonds of one counter Cl anion with four hydrogen atoms of four-OH groups from different MnTHPPCl molecules cooperated by self-assembly of the porphyrin units were first reported.This compound crystallized in the tetragonal space group I4/m with a=1.39928(7)nm,b=1.39928(7)nm,c=0.94498(10)nm,V=1.8503(2)nm3,and Z=2.As a catalyst,MnTHPPCl also showed a high catalytic acti-vity in the conversion from 1-naphthylamine(1-NA)to bis(4-oxo-benzo-2-cyclohexen-1-yl)amine(BOBCHA)via oxidative coupling under mild conditions.     

Manganese(III) Schiff-base complexes involving heterocyclic β-diketone and diethylene triamine

Synthesis, spectral, thermal and coordination aspects of pentadentate Schiff-base complexes of the type [Mn(L)(X)] · H₂O [where H₂L = N,N′–diethylamine bis(1-phenyl-3-methyl-4-acetylimino-2-pyrazoline-5-ol) and X=NCS, NO₃, ClO₄, CN or N₃] are reported. The Schiff-base ligand (H₂L) and metal complexes have been characterized by elemental analysis, FT-IR, ¹H-NMR, magnetic measurements, molar conductivity measurements, electronic spectra, cyclic voltammetric and thermal studies. Magnetic moment values are close to 4.9 B.M. indicating high spin complexes lacking exchange interaction. Infrared spectral data suggest coordination of the secondary amino group making the ligand pentadentate. All complexes are electrochemically inactive, indicating high stability. Thermal decomposition of the Schiff-base complexes indicates loss of water of hydration and decomposition of the ligand. Kinetic parameters such as order of reaction (n) and the energy of activation (E _a) are reported using the Horowitz–Metzger method, indicating first order kinetics and giving the activation entropy (ΔS*), the activation enthalpy (ΔH*) and the free energy of activation (ΔG*).     

Tetracyanoquinodimethane Derivatives of Pentagonal Bipyramidal Complexes of Manganese(II), Iron(II), Nickel(II) and Copper(II) with 2,6-diacetylpyridinebis(semicarbazone)∶ Single Crystal Structure of dichloro[2,6-diacetylpyridinebis (semicarbazone)] Manganese(II)monohydrate

By using the donor ligand 2,6-diacetylpyridinebis(semicarbazone) (DAPSC), pentagonal bipyramidal complexes of Mn(II), Fe(II), Ni(II) and Cu(II) have been obtained. The structure of [MnCl₂(DAPSC)]·H₂O has been determined by X-ray crystallography. Further reactions of these complexes with lithium salts of 7,7',8,8'-tetracyanoquinodimethane (TCNQ) yielded their corresponding adducts.     

Synthesis, Crystal Structure and Characterization of a New Manganese(Ⅱ)Tetracarboxylate

By hydrothermal synthesis,a manganese(Ⅱ)tetracarboxylate [Mn(2,2'-bipyridi-ne)btec)o.5(H2O)]2n(H4btec=1,2,4,5-benzenetetracarboxylic acid)was obtained and characteri-zed by single-crystal X-ray diffraction,IR,elemental analysis and thermogravimetrie analysis.It crystallizes in triclinic,space group P(1),with a=7.721(4),b=8.905(5),c=10.712(6)(A),α=80.899(8),β=70.371(8),γ=78.201(8)°,z=2,V=675.8(7)(A)3,Mr=354.20,Dc=1.741 g/cm3,μ=1.007mm-1,F(000)=360,S=0.956,(△/σ)max=0.000,the final R=0.0490 and wR=0.1262.This compound presents an infinite 1D polymer featuring a double-chain structure.The Mn(Ⅱ)ion is five-coordinated.The four carboxylate groups of btec4- are all deprotonated and coordinated to four Mn atoms in a monodentate fashion,forming a 1D double chain structure with a cavity.Such chains are interconnected by π-π stacking interactions into 2D layers which are further interlinked into a supramolecular structure by hydrogen bonds.     

Synthesis and Crystal Structure of a Chiral Manganese(Ⅲ) Schiff Base Complex

A chiral salency complex,[Mn(Salency)(H2O)2](PF6)·2H2O 1(Salency =(R,R)-N,N'-bis(salicylidene)-1,2-cyclohexanediamine),has been prepared by the reaction of Mn(CH3COO)3·2H2O with Salency and NH4PF6,and was established by X-ray diffraction techniques.The complex crystallizes in triclinic,space group P1 with a=9.299(8),b=10.012(8),c=13.461(11),α=92.037(15),β=92.974(12),γ=93.530(18)°,V=1248.3(18)3,C20H28F6MnN2O6P,Mr = 592.35,Z=2,Dc=1.038 g/cm3,F(000)=608,μ=0.676 mm-1,the final R=0.0651 and wR=0.1880 for 5260 observed reflections with I 2σ(I).     

Spectrophotometric Simultaneous Determination of Zinc(II), Manganese(II) and Iron(II) in Pharmaceutical Preparations Using OSC-PLS

The purpose of this paper is to develop a fast and sensitive spectrophotometric method for the simultaneous determination of zinc(II), manganese(II) and iron(II) in pharmaceutical preparations. The method presented in this work is based on the well-known reaction of these ions with 4-(pyridylazo)resorcinol (PAR)1. The application of quantitative chemometric methods, particularly PLS to multivariate chemical data is becoming more widespread owing to the availability of digitized spectroscop…     

Molecular and Supramolecular Structures of Manganese(Ⅱ) and Cobalt(Ⅱ) Complexes with 1-Carboxymethylpyridinium-4-carboxylate

Two complexes with a zwitterionic dicarboxylate ligand,Mn(L)2(H2O)4 1 and Co(L)2(H2O)4 2(L = 1-carboxymethylpyridinium-4-carboxylate),were synthesized and structurally characterized.Complex 1 crystallizes in monoclinic,space group P21 with a = 6.490(2),b = 19.210(7),c = 7.813(3) ,β = 92.716(5)o,V = 972.9(6) 3,Z = 2,Mr = 487.28,Dc = 1.663 g/cm3,F(000) = 502,μ = 0.749 mm-1,S = 1.060,the final R = 0.0377 and wR = 0.0893 for 3292 observed reflections with I 2σ(I).Complex 2 is isomorphous with 1,with a = 6.478(2),b = 19.052(7),c = 7.742(3) ,β = 92.690(4)o,V = 954.6(6) 3,Z = 2,Mr = 491.28,Dc = 1.709 g/cm3,F(000) = 506,μ = 0.971 mm-1,S = 1.035,the final R = 0.0425 and wR = 0.0809 for 3289 observed reflections with I 2σ(I).In the compounds,the mononuclear [M(L)2(H2O)4] units with trans-octahedral coordination geometry are linked into 3D architectures via hydrogen bonding(or second-sphere coordination) involving carboxylate groups and coordinated water molecules.The 3D networks illustrate a 3,8-connected net with Schlfli symbol(4·62)2(42·623·83).     

Electrophysical Properties of Coordination Compounds Based on Cobalt(II) and Manganese(II) Chlorides and ε-Caprolactam

The metal complex systems based on Co(II) and Mn(II) chlorides and -caprolactam were studied. Temperatures of the phase transition, activation energy of the electrical conductivity, and mobility of the charge carriers in the compounds obtained were determined.     

Dehydrogenative α-Oxygenation of Cyclic Ethers by a High-Valent Manganese(IV)-Oxo Species

High-valent metal-oxo species are typical catalytic cycle intermediates in mono-oxygenases and dioxygenases and commonly react through oxygen atom transfer to substrates. In this work we study a biomimetic model complex with a 1,1’-bis((3,5-dimethylpyridin-2-yl)methyl)-2,2’-bipiperidine ligand system bound to a manganese(IV)-oxo(hydroxo) species and study its formation from manganese(II)-hydroxo and H₂O₂ as well as its reaction with (S)-1-phenylisochromane through dehydrogenative α-oxygenation. The work utilizes density functional theory methods to explore its catalytic cycle and its reactivity patterns. We show that the manganese(IV)-oxo(hydroxo) species is an active oxidant and preferentially the oxo group abstracts a hydrogen atom from substrate with barriers well lower in energy than those found for hydrogen atom abstraction by the hydroxo group. Interestingly, the rate-determining step is the OH rebound rather than the hydrogen atom abstraction, which would imply they would have limited kinetic isotope effect for the replacement of the transferring hydrogen atom by deuterium.     

Manganese(I)-Catalyzed β-Methylation of Alcohols Using Methanol as C1 Source

Highly selective β-methylation of alcohols was achieved using an earth-abundant first row transition metal in the air stable molecular manganese complex [Mn(CO)₂Br[HN(C₂H₄PⁱPr₂)₂]] 1 ([HN(C₂H₄PⁱPr₂)₂]=MACHO-ⁱPr). The reaction requires only low loadings of 1 (0.5 mol %), methanolate as base and MeOH as methylation reagent as well as solvent. Various alcohols were β-methylated with very good selectivity (>99 %) and excellent yield (up to 94 %). Biomass derived aliphatic alcohols and diols were also selectively methylated on the β-position, opening a pathway to “biohybrid” molecules constructed entirely from non-fossil carbon. Mechanistic studies indicate that the reaction proceeds through a borrowing hydrogen pathway involving metal–ligand cooperation at the Mn-pincer complex. This transformation provides a convenient, economical, and environmentally benign pathway for the selective C−C bond formation with potential applications for the preparation of advanced biofuels, fine chemicals, and biologically active molecules     

A Homogeneous Chiral Manganese(III)–Salphe Catalyst for Enantioselective Epoxidation of Olefins

A new chiral Mn(III)–Salphe catalyst was synthesized from natural amino acid (R)-phenylalanine and 3,5-di-tert-butyl-hydroxybenzaldehyde and applied to the asymmetric epoxidations of unfunctionalized olefins in ionic liquids. Satisfactory enantioselectivities (79% < ee < 93%) and good yields were achieved when NaClO was used as oxidant. We found that both the pH value (11.3) and reaction temperature (15 °C) were crucial for the epoxidation reactions. In our reaction system, NH₄OAc was unnecessary. We proposed that alcoholic hydroxyls in the Mn(III)–Salphe compound played the role of axial ligand. However, the reaction time was longer than when using Jacobsen's catalyst because of the structure of the Mn(III)–Salphe compound, in which coordination geometries by the two alcoholic hydroxyls with certain angles affected the substrate approaching the Mn(V) = 0 center. The chiral ligand was characterized by the combination of infrared, ultraviolet, and visible spectra and ¹H NMR.

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Manganese(II), nickel(II) and copper(II) complexes of (1,3-bis-aminomethyl) cyclohexane-N,N,N′,N′-tetrakisbenzimidazole

Summary Mn^II, Ni^II and Cu^II complexes of (1,3-bis-aminomethyl)-cyclohexane-N,N,N,N-tetrakisbenzimidazole (CDTB) have been prepared and characterized by spectral techniques. The complexes are monomeric and pseudo-octa-hedral, as evidenced by their e.p.r. spectra and analytical data. Parameters ², ², ² and for Cu^II complexes, and the crystal field splitting parameter (10 Dq) together with the Nephelauxetic ratio (), for Ni^II complexes, are reported.     

Determination of Immunoglobulin G by a Hemin–Manganese(IV) Oxide-Labeled Enzyme-linked Immunosorbent Assay

An enzyme-linked immunosorbent assay (ELISA) is reported for human immunoglobulin G based on synthesized hemin–MnO₂ nanocomposite as the label. Enhanced sensitivity was obtained due to the increased catalytic activity of the hemin–MnO₂ nanocomposite toward 3,3′,5,5′-tetramethylbenzidine compared to hemin and MnO₂ alone. The synthesized hemin–MnO₂ nanocomposite was characterized by transmission electron microscopy and its catalytic activity to 3,3′,5,5′-tetramethylbenzidine was investigated by ultraviolet–visible absorption spectroscopy. After assembly of the sandwich-type immunoassay in the 96 wells of the plate the hemin–MnO₂-based label catalyzed 3,3′,5,5′-tetramethylbenzidine into blue compounds that were monitored by a plate reader. The absorbance increased with the concentration of human immunoglobulin G. The immunoassay displayed high sensitivity, a long linear dynamic range, and good selectivity for human immunoglobulin G. The immunoassay was also used for the determination of human immunoglobulin G in serum with favorable results. The developed assay combines the high throughput and low cost of ELISA with the simplicity of nanocomposite labeling and is suitable for application in clinical diagnosis.     

Temperature-dependent Syntheses of Two Manganese(Ⅱ) Coordination Compounds Based on an Ether-bridged Tetracarbolylic Acid

0D dinuclear manganese(Ⅱ) coordination compound and 1 D chain manganese(Ⅱ) coordination polymer, namely [Mn_2(μ-L)(phen)4]·4 H_2 O(1) and {[Mn_2(μ5-L)(phen)_2]·H_2O}n(2), have been constructed hydrothermally using H4 L(H4 L = 2,3,3',4'-diphenyl ether tetracarboxylic acid), phen(phen = 1,10-phenanthroline), and manganese chloride at 120 and 160℃, respectively. The products were isolated as stable crystalline solids and were characterized by IR spectra, elemental analyses, thermogravimetric analyses(TGA), and single-crystal X-ray diffraction analyses. Single-crystal X-ray diffraction analyses revealed that two compounds crystallize in the triclinic or monoclinic system, space group P1 or P2_1/c. Compound 1 discloses a discrete dimeric structure, which is assembled into a 3 D supramolecular framework through O–H···O hydrogen bond. Compound 2 has a chain structure. Structural differences between compounds 1 and 2 are attributed to the different reaction temperature. Magnetic studies for compound 2 demonstrate an antiferromagnetic coupling between the adjacent Mn(Ⅱ) centers.     

Selective Labeling of Peptides with o-Carboranes via Manganese(I)-Catalyzed C−H Activation

A robust method for the selective labeling of peptides via manganese(I) catalysis was devised to achieve the C-2 alkenylation of tryptophan containing peptides with 1-ethynyl-o-carboranes. The manganese-catalyzed C−H activation was accomplished with high catalytic efficiency, and featured low toxicity, high functional group tolerance and excellent E-stereoselectivity. This approach unravels a promising tool for the assembly of o-carborane with structurally complex peptides of relevance to applications in boron neutron capture therapy.     

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…