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1.
Design and synthesis of a triangular manganese compound, [Mn3O4(H2O)2(phen)4](NO3)4?·?3H2O (1) with mono-µ-oxo and di-µ-oxo, is described. The complex has been characterized by elemental analysis, spectroscopy, single crystal and powder diffraction measurements, thermogravimetric analysis, etc. Bond Valence Sum calculations and X-ray photoelectron spectroscopy reveal that each manganese at each vertex of the triangle is +IV oxidation state. Variable temperature magnetic measurements show strong antiferromagnetic coupling between metal ions with the following set of parameters: g?=?1.99, J 1?=??50.0?cm?1, and J 2?=??90.2?cm?1 (where J 1 describes the interaction across the two mono-µ-oxo bridges and J 2 is the exchange coupling across the di-µ-oxo bridge). The compound breaks down in three steps when heated from room temperature to 900°C. The final ash of the compound is confirmed by infrared spectrum with standard MnO2.  相似文献   

2.
Two tetranuclear manganese complexes, [Mn4(L1)6](ClO4)2?2.75H2O (1) [HL1 = 4-methyl-2-((pyridin-2-ylmethylene)amino)phenol] and [Mn4(L2)4(NO3)3(OH)]?pz?3H2O (2) [HL2 = (1H-pyrazol-1-yl)(pyridin-2-yl)methanol, pz = pyrazole], have been synthesized and characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, and magnetic measurements. The structural analysis revealed that the central manganese ion is linked with three apical manganese ions through six phenoxo-bridges creating a Mn4O6 core for 1; 2 has a cubane-like topology with the Mn(II) ions and the deprotonated oxygens from L2 alternatively occupying vertices. The magnetic studies indicated a weak ferromagnetic coupling interaction (J = 0.48 ± 0.087 cm?1, g = 2.00, θ = ?0.78 K) for 1 and a weak antiferromagnetic spin-exchange interaction (J1 = ?0.50 ± 0.075 cm?1, J2 = ?0.13 ± 0.082 cm?1, g = 1.98) between Mn(II) ions for 2. The magnetostructural correlations of the two Mn4 clusters have been discussed tentatively.  相似文献   

3.
A 1D coordination polymer of manganese(III) with a hydrazone‐based ligand, [Mn2(L)(μ‐OCH3)2(OHCH3)2]n ( 1 ), was synthesized and characterized by elemental analyses and spectroscopic methods {H4L = bis[(2‐hydroxynaphthalen‐1‐yl)methylene]adipohydrazide}. The crystal structure of 1 was determined by X‐ray crystallography. The two dianionic domains of the ligand adopt trans configuration, and each coordinates in a tridentate mode via the O, N, O′‐donor atoms to a MnIII ion forming a dinuclear compound. The methoxy ligands provide an asymmetric bridge between two central manganese atoms, which lead to the formation of a 1D coordination polymer. A 2D supramolecular structure is formed by hydrogen bonding interactions between the 1D chains. Although the methoxy ligands are labile, the polymer preserves its oligonuclearity in the solution. Temperature‐dependent magnetic susceptibility studies proved the presence of a weak antiferromagnetic interaction between manganese(III) ions with J = –3.2 cm–1, which results from axial distortion of the manganese coordination environment. Compound 1 showed catalase‐like activity in disproportionation of H2O2.  相似文献   

4.
Two new binuclear complexes, [Mn2(μ-dmpo)2(SCN)4(H2O)2] (1) (where dmpo?=?3,5-dimethylpyridine N-oxide), [Mn2(μ-po)2(H2O)6I2]I2 (2) (where po?=?pyridine N-oxide), have been synthesized and their crystal structures determined by X-ray crystallography. Complexes 1 and 2 crystallize in monoclinic, space group P21/c, with unit cell dimensions a?=?8.8836(18)?Å, b?=?15.450(3)?Å, c?=?15.484(3)?Å, β?=?91.020(3)° for 1, and a?=?8.8352(13)?Å, b?=?17.927(3)?Å, c?=?8.3338(12)?Å, β?=?103.765(2)° for 2. In each binuclear complex two Mn(II) were bridged by two 3,5-dimethylpyridine N-oxides or by two pyridine N-oxides and the distances between the bridged Mn(II) ions are 3.599?Å for 1 and 3.552?Å for 2. Variable temperature (4–300?K) magnetic measurements were performed for 1 and the susceptibility data were fitted by using a binuclear Mn(II) magnetic coupling formula producing the 2J?=??2.17?cm?1.  相似文献   

5.
A new oxamato-bridged NiIICuIINiII species, [Ni(iprtacn)]2[Cu(pba)(H2O)0.5](BPh4)2 (1), (iprtacn?=?1,4,7-triisopropyl-1,4,7-triazacyclononane; pba?=?1,3-propylenebis(oxamato)) has been synthesized and structurally as well as magnetically characterized. Complex 1 has a discrete trinuclear NiIICuIINiII structure: Two nickel(II) ions are bridged by [Cu(pba)]2? with the macrocyclic ligand iprtacn a terminal ligand of nickel(II). Fitting the magnetic data of 1 led to g Cu?=?2.16, g Ni?=?2.18, J?=??112.5?cm?1, D?=?±7.78?cm?1. The irregular spin state structure and interaction of complex 1with DNA are described here.  相似文献   

6.
The reaction of the trinuclear oxo-centered mixed-valence complex [Mn3O(O2CPh)6(Py)2(H2O)] with 2,2′-bipyridyl (Bipy) and another potential tripodal ligand affords the title compound [Mn3(PhCO2)6(Bipy)2] · H2O in good yield. The X-ray crystallographic diffraction study reveals that three mangenese ions are arranged in a linear mode with Mncenter-Mnterminal and Mnterminal-Mnterminal diatances of 3.588 and 7.176 Å, respectively. Molar magnetic susceptibility of the compound gradually decreases from 12.23 (300 K) to 4.45 cm3 K mol?1 (2 K). Taking into account the structure of this compound, the data in the 2.0–300 K range were fit to the appropriate theoretical expression to give J = ?2.73 cm?1, ρ = 2.07%, N a = ?0.0004 cm3 mol?1, g = 1.992, and R 2 = 0.99996. The magnetization versus external magnetic field measurements at 2 K shows that the ground state is S T = 5/2.  相似文献   

7.
Abstract

We synthesized an l–arginine complex with the formula [Cu(l–Arg)2(NCS)]·(NCS)·H2O (1) (l–Arg = l–arginine). Two cis-chelated l–arginine zwitterions form the basal plane, while the weakly N-bonded isothiocyanate is located at the apex of the distorted square pyramidal structure (τ?=?0.143). The non-coordinated NCS? anions held layers together in a 3-D supramolecular network. The crystal structure, spectroscopic (FT–IR, Raman, NIR–Vis–UV, EPR) and magnetic properties of 1 have been compared with [Cu(l–Arg)(NCS)2] (2). For 1, two absorptions are observed for ν(C?=?N) stretching vibrations, corresponding to NCS? ions N-bonded to the central Cu(II) (2077?cm?1) and in the lattice (2057?cm?1). In 2 a single band is observed at 2102?cm?1, indicating equivalent NCS? ions in the structure. The EPR spectra of complexes show anisotropic signal with g and g|| 2.062, 2.235 (1), and 2.08, 2.225 (2) characteristic for cis-N2O2 and N3O donor sets in the xy plane, respectively. The unpaired electron mainly occupies the dx2–y2 orbital, also confirmed by the single envelope of d–d bands at ca. 16,000?cm?1 for 1 and 16,500?cm?1 for 2. The magnetic properties ofcompounds are characteristic of a very weak antiferromagnetic interaction with J?=??0.055?cm?1 and J?=??0.096?cm?1 for 1 and 2, respectively.  相似文献   

8.
The crystal structures, magnetic properties, and catalase-like activities of assymmetric dinuclear manganese(III, III) complexes, [Mn2III, III(spa)2(μ-Me3CCO2)(Me3CCO2)(CH3OH)] ( 1 ) and [Mn2III, III(vpa)2(μ-Me3CCO2)(Me3CCO2)(CH3OH)] ( 2 ), (H2spa = 3-salicyclideneamino-1-propanol, H2vpa = O-vanillin), were reported. The crystal structures of complexes 1 and 2 consist of the same discrete asymmetric coordination environment of dinuclear clusters, where the two manganese atoms are bridged by two alkoxo oxygens of the spa or vpa ligands and one bidentate carboxylate ion, whereas an additional oxygen atom of monodentate carboxylate coordinated to the first metal ion, and the second metal ion was coordinated by one oxygen atom of the solvent CH3OH. Magnetic investigations (2–300 K) reveal an intramolecular antiferromagnetic spin exchange interaction with axial-field splittings: J = ?12.3 cm?1 (D = ?0.10 cm?1) and J = ?13.3 cm?1 (D = ?0.15 cm?1) for complexes 1 and 2 , respectively. The complexes should show catalase-like activity for H2O2 disproportionation in CH3OH solvent at 25° with rate constants of k = 6.35 dm3moI?1s?1 and 6.20 dm3mol?1s?1 for complexes 1 and 2 , respectively.  相似文献   

9.
The influence of pH for the reaction system involving CuCl2?·?2H2O, imidazole (Him) and phenylacetic acid (HL) at room temperature was investigated. Cu2(Him)4L4?·?2H2O (1) and Cu3(Him)2(im)2L4 (2) were synthesized at pH 6.5 and 7.5, respectively. In 1, the Cu is coordinated by two nitrogen atoms of two Him and three oxygen atoms from three phenylacetates to form a square pyramid CuN2O3. Adjacent square pyramids share edges to form Cu2N4O4 dimers, which are assembled by hydrogen bonds into a 2-D layer parallel to the (001) plane. In 2, copper atoms are interlinked by im? and L? to form a 2-D layer parallel to (100). The resulting layers have C–H···O hydrogen bonds leading to a 3-D supramolecular architecture. Variable temperature magnetism of 1 and 2 suggests a weak ferromagnetic or antiferromagnetic coupling exchange (J?=?0.58?cm?1 for 1, J?=??10.24?cm?1 for 2).  相似文献   

10.
The trinuclear manganese(II) complexes [Mn3(L1)2(μ‐OAc)4]·2Et2O {HL1 = (1‐hydroxy‐4‐nitrobenzyl)((2‐pyridyl)methyl)((1‐methylimidazol‐2‐yl)methyl)amine} ( 1·2EtOH ), [Mn3(L2)2(μ‐OAc)4] {HL2 = ((1‐methylimidazol‐2‐yl)methyl)(1‐hydroxybenzyl)amine} ( 2 ) and [Mn3(L3)2(μ‐OAc)6] {L3 = bis(1‐methylimidazol‐2‐yl)methanone} ( 3 ) were synthesized. The compounds were characterized by X‐ray crystallography, mass spectrometry, IR, UV‐vis spectroscopy, and elemental analysis. The manganese atoms in 1 and 2 are bridged by phenol moieties of the ligands and acetates. In 3 they are only bridged by acetates in a mono‐ and bi‐dentate way. The resulting Mn···Mn distances are 3.233(1) Å ( 1 ), 3.364(1) Å ( 2 ) and 3.643(7) Å ( 3 ). In the present compounds different limiting cases for the phenomenon of the carboxylate shift are realized. Besides symmetric mono‐ and bi‐dentate bridging an unusual intermediate is also observed. 1·2EtOH is the first example of a trinuclear model for the OEC that shows catalase activity. Furthermore it was characterized by temperature dependent magnetic susceptibility measurements and a total spin ground state of St = 5/2 was found. The results for 1 reveals antiferromagnetic coupling between the central and the terminal manganese ions, with J = ?1.2 cm?1, g = 2.00 (fixed), χTIP = 150×10?6 cm3mol?1.  相似文献   

11.
The reactions of Mn2+ ion with 4-nitrobenzene-1,2-bicarboxylic acid in the presence of bipyridyl-type coligands gave two new manganese(II) coordination polymers, [Mn2(Nbdc)2(Bipyp)(H2O)4] n (I) and [Mn2(Nbdc)2(Bipye)(H2O)4] n (II) (H2Nbdc = 4-nitrobenzene-1,2-bicarboxylic acid, Bipyp = 1,3-bi(4-pyridyl)propane, and Bipye = 1,2-bi(4-pyridyl)ethane). Both two complexes contain uniform carboxyl-bridged manganese chains with the composition of [Mn2(Nbdc)2(H2O)4] n , which are interlinked by interchain Bipyp/Bipye spacers to afford two closely-related layers (CIF files CCDC nos. 1008182 (I) and 1008183 (II)). Magnetic studies for two compounds show the presence of similar antiferromagnetic couplings between the adjacent Mn2+ ions through the carboxyl bridges, the best fittings to the experimental magnetic susceptibilities gave J =–0.20 cm–1 and g = 1.96 for I, and J =–0.24 cm–1 and g = 1.98 for II. Similar magnetic parameters and thermal behaviors further verify that two compounds possess closely-related structures.  相似文献   

12.
Reactions of copper salts, zoledronic acid, and 2,2′-bipyridine/1,10-phenanthroline in aqueous ethanolic solutions afforded four phosphonate oxygen-bridged copper complexes, Cu(bipy)(H4zdn)(HSO4) (1), [Cu2(bipy)2(H2zdn)(H2O)(Cl)]·4H2O (2), [Cu2(phen)2(H2zdn)(H2O)(Cl)]·2.5H2O (3), and [Cu3(bipy)3(H4zdn)(H2zdn)(SO4)]·5H2O (4) (H5zdn = zoledronic acid, bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline). The copper centers of 14 have square pyramidal coordination geometries. The Cu(II) ions are coordinated to bipy/phen, zoledronate, and HSO4?/Cl? forming mononuclear units for 1, dinuclear for 2 and 3, and trinuclear for 4. These building units are further extended into 3-D supramolecular networks via multiple hydrogen bond interactions. Temperature-dependent magnetic properties of 2 and 4 suggest weak antiferromagnetic coupling (J = ?4.53(8) cm?1 for 2, J = ?1.69(4) cm?1 for 4). The antitumor activity of 2 was evaluated against the human lung cancer cell line and indicates effective time- and dose-dependent cytotoxic effects.  相似文献   

13.
Weak anti-ferromagnetic coupling is observed in a mononuclear copper(II) complex, [Cu(Pid)(OSO3)(H2O)]?·?(H2O) (Pid?=?2,2′-(1,10-phenanthrolin-2-ylimino)diethanol). The Cu(II) complex is a distorted square pyramid. Analysis of the crystal structure indicates that there are two types of magnetic coupling pathways, where one pathway involves π–π stacking between adjacent complexes and the second one involves the O–H?···?O hydrogen bonds between adjacent complexes. The variable-temperature magnetic susceptibilities show that there is a weak anti-ferromagnetic coupling between adjacent Cu(II) ions with Curie–Weiss constant θ?=??13.71?K?=??9.93?cm?1. Theoretical calculations reveal that the π–π stacking resulted in anti-ferromagnetic coupling with 2J?=??6.30?cm?1, and the O–H?···?O hydrogen-bonding pathway led to a weaker anti-ferromagnetic interaction with 2J?=??3.38?cm?1. The theoretical calculations also indicate that anti-ferromagnetic coupling sign from the π–π stacking accords with the McConnell I spin-polarization mechanism.  相似文献   

14.
Reactions of manganese benzoate dihydrate and lanthanide nitrate hexahydrate with 2‐(hydroxymethyl)pyridine (hmpH) as ligand in the mixture solutions of acetonitrile and ethanol according to different molar ratios of NEt3 generated two kinds of Mn‐Ln compounds [MnIII4LaIII2(O)2(hmp)7(PhCO2)2(NO3)5] ·5H2O ( 1 ) and [MnIII2GdIII2(hmp)6(PhCO2)4(NO3)2] ·3CH3CN·3C2H5OH·2H2O ( 2 ). By comparison of the two compounds, there exist considerable effects of reaction alkalinity on the structures and magnetic properties of products. Compound 1 possesses a core of [MnIII4LaIII2(μ 4‐O)(μ 3‐O)(μ 3‐OR)(μ 2‐O)7]2−, which comprises three face‐sharing defected cubane units. The core topology represents a new core type of Mn‐Ln clusters. Compound 2 has a planar‐butterfly structure. The solid‐state dc magnetic susceptibility analyses indicate the antiferromagnetic interactions within compound 1 and ferromagnetic interactions within compound 2 . Compound 1 has an S  = 0 ground state, while compound 2 possesses an S  = 11 ground state, fitting of the dc data for the tetranuclear Mn2Gd2 with the Magpack program gives parameters of J Mn‐Mn  = 3.11 cm−1, J Mn‐Gd  = 0.02 cm—1 and g  = 1.96.  相似文献   

15.
Three coordination polymers of Robson-type macrocycles, {[Cu4L1(4,4′-bipy)2]·4ClO4·H2O} (1), {[Cu4L2(4,4′-bipy)4]·2CH3CN·4ClO4·2H2O} (2), and {[Zn2L2(4,4′-bipy)2]·(ClO4)2} (3) (where H2L1 and H2L2 are the [2?+?2] condensation products of 1,3-diaminopropane with 2,6-diformyl-4-methylphenol and 2,6-diformyl-4-fluorophenol, respectively), have been synthesized and characterized. Magnetic susceptibility was measured for 1 and 2 from 2 to 300?K. The optimized magnetic data were J?=?–368.5?cm?1, J′?=?40.5?cm?1 with R?=?1.69?×?10?6 for 1 and J?=?–291.22?cm?1, J′?=?83.74?cm?1, ρ = 0.00168 with R?=?1.8?×?10?11 for 2, respectively. The data reveal strong antiferromagnetic interactions between two Cu(II) ions in the macrocyclic unit and ferromagnetic interaction between the Cu(II) ions in two adjacent macrocyclic units for 1 and 2.  相似文献   

16.
In an attempt to employ salicylic acid (HOsalH), 2,6-dihydroxy benzoic acid {(HO)2PhCO2H}, and naphthalene-1,8-dicarboxylic acid {1,8-naph(CO2H)2} in Mn(III) salicylaldoximate chemistry as a means to alter the structural identity of the hexanucluear clusters usually obtained from this reaction system, we have isolated a family of hexanuclear Mn(III) complexes based on salicyladloxime (saoH2) and 2-hydroxy-1-naphthaldehyde oxime (naphthsaoH2). Five hexanuclear clusters, [Mn6O2(sao)6(HOsal)2(EtOH)4]·EtOH (1·EtOH), [Mn6O2(sao)6{1,8-naph(CO2Me)(CO2)}2(MeOH)6]·3MeOH (2·3MeOH), [Mn6O2(naphthsao)6{1,8-naph(CO2Et)(CO2)}2(EtOH)6] (3·2MeOH), [Mn6O2(naphthsao)6(MeCO2)2(EtOH)4]·2H2O (4·2H2O), and [Mn6O2(naphthsao)6{(HO)2PhCO2}2(EtOH)4]·4EtOH (5·4EtOH), have been synthesized and characterized by single-crystal X-ray crystallography. The magnetic properties of 3, 4, and 5 are discussed.  相似文献   

17.
The tape‐like chain {[(tptz)MnII(H2O)MnIII(CN)6]2MnII(H2O)2}n?4n MeOH?2n H2O based on the anisotropic building block hexacyanomanganate(III) exhibits long‐range magnetic ordering below 5.1 K as well as single‐chain magnetic behavior at lower temperatures with an effective energy barrier of 40.5(7) K.  相似文献   

18.
One nonlinear and one linear trinuclear copper(II) complex [Cu3(dien)2(pdc)2CH3OH]2?·?6CH3OH (1) and [Cu3(pdc)2(CH3OH)6(H2O)4] (2) were prepared and characterized structurally, where dien is diethylenetriamine and pdc3? the trianion of 3,5-pyrazoledicarboxylic acid. Both complexes consist of 3,5-pyrazoledicarboxylato-bridged trinuclear copper(II) centers. In 1, copper(II) ions are five-coordinate in distorted square pyramids with bond angles 164.78° for Cu(1)–Cu(2)–Cu(3) and 164.51° for Cu(4)–Cu(5)–Cu(6). In 2, the three copper(II) ions are six-coordinate with elongated octahedral geometry. The trinuclear units of 1 and 2 interact through hydrogen bonds to form 3-D and 2-D supramolecular networks, respectively. Variable temperature magnetic susceptibility measurements show that 1 and 2 are antiferromagnetically coupled with J values of ?11.2 and ?13.3?cm?1.  相似文献   

19.
Two types of manganese complexes with [Mn4] cores featuring the unusual distorted cube topology are presented, the first of which comprises new modifications of the reported complex [MnIII4(sao)4(saoH)4]·3CHCl3: [Mn4(sao)4(saoH)4]·1.32(C4H10O)·0.43(CH4O) ( 1a ) and [Mn(sao)4(saoH)4]·0.5(CH4O)·0.5(C2H3N) ( 1b ) sao = salicylaldoxime. The second, 0.55[Mn4Cl4(C12H9N2O)4(CH3OH)2(H2O)2]·0.45[Mn4Cl4(C12H9N2O)4(CH3OH)4] ( 2 ), is the first reported case of a {MnII4} core of this topology besides known {MnIII4} compounds. Differences between the {MnII4} and {MnIII4} situation are discussed, and so far overlooked differences in magnetic properties between different {MnIII4} compounds are pointed out.  相似文献   

20.
A tetranuclear manganese complex of the composition {Mn4[(Py)C(Ph)NO]4(CH3CH2OH)3(CH3CH2O)Cl3}·2H2O ( 1 ) was synthesized by solvothermal reaction, and characterized by X‐ray single crystal diffraction, IR spectroscopy, and elemental analysis. X‐ray analysis revealed that complex 1 contains a [Mn4(NO)4]4+ core with three MnII atoms displaying distorted octahedral arrangements and one MnII ion exhibiting a trigonal bipyramidal arrangement. Low‐temperature magnetic susceptibility measurement for the solid sample of 1 revealed antiferromagnetic MnII ··· MnII interactions.  相似文献   

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