共查询到20条相似文献,搜索用时 656 毫秒
1.
The stepwise synthesis of mononuclear (4f) and heterodinuclear (3d–4f) Salen-like complexes has been investigated through structural determination of the intermediate and final products occurring in the process. In the first step, reactions of ligand H 2L and Ln(NO 3) 3 · 6H 2O give rise to three mononuclear lanthanide complexes Ln(H 2L)(NO 3) 3 [H 2L = N, N′-ethylene-bis(3-methoxysalicylideneimine), Ln = Nd (1), Eu (2) and Tb (3)], in which N, N′-ethylene-bis(3-methoxysalicylideneimine) acts as tetradentate ligands with the O 2O 2 set of donor atoms capable of effective coordination. These species are fairly stable and have been isolated. Then, addition of Cu(Ac) 2 · H 2O to the mononuclear lanthanide complex yields expected heterodinuclear (3d–4f) complexes Cu(L)Ln(NO 3) 3 · H 2O [Ln = Nd (4) and Eu (5)] where the Cu(II) ion is inserted to the inner N 2O 2 cavity. Luminescent analysis reveals that complex 3 exhibits characteristic metal-centered fluorescence of Tb(III) ion. However, the characteristic luminescence of both Sm(III) and Eu(III) ions is not observed both in solution and solid state of the complexes. 相似文献
2.
The interaction between Ac-AMP2, a lectin-like small protein with antimicrobial and antifungal activity isolated from Amaranthus caudatus, and N, N′, N″-triacetyl chitotriose was studied using 1H NMR spectroscopy. Changes in chemical shift and line width upon increasing concentration of N, N′, N″-triacetyl chitotriose to Ac-AMP2 solutions at pH 6.9 and 2.4 were used to determine the interaction site and the association constant Ka. The most pronounced shifts occur mainly in the C-terminal half of the sequence. They involve the aromatic residues Phe 18, Tyr 20 and Tyr 27 together with their surrounding residues, as well as the N-terminal Val-Gly-Glu segment. Several NOEs between Ac-AMP2 and the N, N′, N″-triacetyl chitotriose resonances are reported. 相似文献
3.
Three different synthetic routes have been explored for the synthesis of the mono-N-substituted phosphinoamine N-ethyl, N′bis[2(diphenylphosphino)phenyl]propane-1,3-diamine: (a) selective alkylation of N,N′bis[2(diphenylphosphino)phenyl]propane-1,3-diamine; (b) linkage of the different fragments of N-ethyl, N′bis[2(diphenylphosphino)phenyl]propane-1,3-diamine; (c) selective acylation of N,N′bis[2(diphenylphosphino)phenyl]propane-1,3-diamine followed by acetyl reduction. While approaches (a) and (b) were unsuccessful, N-ethyl, N′bis[2(diphenylphosphino)phenyl]propane-1,3-diamine was obtained by route (c) via separation of the mono- and di-alkylated P 2N 2-species obtained from reduction, through complexation of Ni(NO 3) 26H 2O followed by demetallation reaction with KCN. Additional related phosphinoamine chelates and phosphonium adducts were synthesized and characterized by conventional physico–chemical techniques. 相似文献
4.
The X-ray structure is reported for the complex Cu 2(medpco-2H)Cl 2, (medpco = N, N′-bis- N, N-dimethylaminoethyl)pyridine-2,6-dicarboxamide 1-oxide. The complex is triclinic,
, a=8.313(4), B=11.403(5), C=11.611(3) Å, =91.66(3), β=108.99(4), γ=109.60(3)° and Z=2. The deprotonated ligand (medpco-2H) 2− acts as a binulceating ligand, producing an N-oxide-bridged complex. Each copper in Cu 2(medpco-2H)Cl 2 is five-coordinate, being coordinated by a bridging N-oxide oxygen, a deprotonated amide nitrogen, a tertiary amine nitrogen and two bridging chlorides. The complex does not exhibit significant magnetic interaction, and this may be the result of distortion of the bridging geometry from planarity. A range of other, apparently N-oxide-bridged, complexes of the type Cu 2(medpco-2H)X 2 is reported. The complex Cu 2(medpco-2H)Br 2·H 2O is strongly antiferromagnetic, with magnetic data closely fitting the expected binuclear structure. 相似文献
5.
The ligand N, N′-bis[2,2-dimethyl-4-(2-hydroxyphenyl)-3-aza-3-buten] oxamide with two identical coordination sites reacts with copper ions in its tetradeprotonated form to yield the dinuclear complex [Cu 2(C 24H 26N 4O 4)]·H 2O. The structure of this compound has been determined by the X-ray diffraction method. The crystals are orthorhombic with a = 11.744(1), B = 16.369(2), C = 26.340(3) Å, V = 5064(1) Å 3, Z = 8, space group Pbca. The oxamide is in a trans conformation with two different environments for the copper centres, a (4 + 1) coordination mode for the first one and a square planar environment for the other one. The water molecule is not directly bound to a copper centre, but involved in hydrogen bonding with the two oxygen atoms of an N 2O 2 coordination site. Indeed, extra coordination comes from a phenolic oxygen atom belonging to an adjacent dinuclear unit. Static susceptibility measurements point to a strong intrapair antiferromagnetic exchange interaction of 2 J = −520(±4) cm −1 and possibly an interpair ferromagnetic exchange interaction of 10(±5) cm −1. 相似文献
6.
The chlorocadmate(II) systems of (H 2me 2pipz)[Cd 2Cl 6(H 2O) 2] (1) and (H 2mepipz) 2[Cd 3Cl 10(H 2O)] (2) (L = me 2pipz = N, N′-dimethylpiperazine; L′ = mepipz = N-methylpiperazine) were prepared and their structural and thermal properties investigated. Compound 1 is monoclinic, space group P2 1/ c, A = 7.664(1), B = 7.472(4), C = 15.347(1) Å, β = 99.468(7)°, Z = 2, R = 0.024. The crystal structure consists of organic cations and infinite one-dimensional chains of [CdCl 3(H 2O)] n3− anions. Each Cd atom is octahedrally surrounded by bridged and terminal chlorine atoms and by a water molecule, which is in trans position with respect to the terminal chlorine atom. Inter- and intrachain hydrogen bond interactions between the terminal chlorine atoms and the water molecules contribute to the crystal packing. Compound 2 is orthorhombic, space group Cmc2 1, A = 15.286(3), B = 13.354(3), C = 13.154(3) Å, R = 0.023. The crystal structure consists of organic dications and infinite chains of [Cd 2Cl 6(CdCl 4H 2O] n4− units running along the [001] axis. Each unit is formed of regularly alternate six-coordinated Cd atoms, one of them linking one pentacoordinated Cd atom which completes its coordination througha water molecule. A strong hydrogen bond interaction involving the organic dication and the inorganic chain contributes to the crystal packing. Differential hydrogen bond interaction involving the organic dication and the inorganic chain contributes to the crystal packing. Differential scanning calorimetry measurements did not show the presence of any structural phase transitions. The structures are compared with those of (H 2pipz)[Cd 2Cl 6(H 2O) 2] (3), (H 2mepipz)[Cd 2Cl 6(H 2O) 2]·H 2O (4) and (H 2mepipz)[Cd 2Cl 6] (5) (L = pipz = piperazine, L′ = mepipz = N-ethylpiperazine). 相似文献
7.
1,10-Phenanthroline-5,6-dione (C 12H 6N 2O 2 (1)) reacts with V(η 6-mesitylene) 2 and Ti(η 6-toluene) 2 affording coordination compounds of general formula M( O, O′---C 12H 6N 2O 2) 3 (M=Ti (2); M=V (3)) which further react with TiCl 4 or TiCp 2(CO) 2 yielding the tetrametallic species M( O, O′---C 12H 6N 2O 2--- N, N′) 3(M′L n) 3 (M=V, M′L n=TiCl 4 (4); M=Ti, M′L n=TiCp 2 (5); M=V, M′L n=TiCp 2 (6)). The complex salt [Fe( N, N′---C 12H 6N 2O 2) 3][PF 6] 2 (7) has been obtained from iron(II) chloride tetrahydrate and 1 in the presence of NH 4PF 6. The reaction of 7 with TiCp 2(CO) 2 affords the tetrametallic derivative [Fe( N, N′---C 12H 6N 2O 2--- O, O′) 3(TiCp 2) 3][PF 6] 2 (8). TiCl 2(THF) 2 reacts with MCp 2( O, O′---C 12H 6N 2O 2) to give MCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2 (M=Ti (9); M=V (10)). By reaction of TiCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2 (9) with C 12H 6N 2O 2, the bimetallic derivative TiCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2( O, O′---C 12H 6N 2O 2) (11) has been prepared, which readily adds to TiCl 4, to give the trimetallic titanium derivative TiCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 4 (12). VCp 2( O, O′---C 12H 6N 2O 2--- N, N′)TiCl 2 (10) reacts with the tris-chelate iron(II) cation 7 affording the heptametallic cationic complex [Fe( N, N′---C 12H 6N 2O 2--- O, O′)TiCl 2( N, N′---C 12H 6N 2O 2--- O, O′)VCp 2] 3 +2 isolated as the hexafluorophosphate 13. 相似文献
8.
The mononuclear manganese(III) complexes [C 5H 10NH 2][MnL 2] [L 2−=a substituted N-(2-hydroxybenzyl)glycinate (hbg 2−) viz. 3,5-dibromo- (3,5-Br-hbg 2−), 3,5-dichloro- (3,5-Cl-hbg 2−), 3-methyl-5-chloro- (3,5-Me,Cl-hbg 2−), 5-bromo- (5-Br-hbg 2−), 5-chloro- (5-Cl-hbg 2−), 5-nitro- (5-NO 2-hbg 2−) or N-(5-nitro-2-hydroxybenzyl)sarcosine (5-NO 2-hbs 2−)] have been synthesised by reaction of the appropriate ligand with manganese(II) perchlorate under ambient conditions in a 2:1 molar ratio using piperidine as base. The structures of three of these complexes, [C 5H 10NH 2][Mn(3,5-Cl-hbg) 2] (2), [C 5H 10NH 2][Mn(5-NO 2-hbg) 2] (6) and [C 5H 10NH 2][Mn(5-NO 2-hbs) 2] (7) have been elucidated by single-crystal X-ray crystallography and each displays two similar, independent [MnL 2] − ions in the asymmetric unit linked via piperidinium cations through hydrogen bonding. The ligands co-ordinate in a facial tridentate fashion with the three donor atoms being the phenolate and carboxylate oxygens and the amine nitrogen. The geometry at the Mn centres is compressed rhombic octahedral consistent with a pseudo-Jahn–Teller compression along the Mn–O(phenolate) axis. Mean bond lengths are in the ranges 1.886–1.889 Å for the Mn–O(phenolate), 2.062–2.125 Å for the Mn–O(carboxylate) and 2.091–2.184 Å for the Mn–N(amine) distances. The magnetic susceptibility and electronic and IR spectroscopic data are discussed with reference to the crystal structures. 相似文献
9.
Carbohydrate-bearing polymers of biologically inert design are versatile tools to delineate functional aspects of oligosaccharides. Binding of synthetic N-substituted polyacrylamide (PAA) conjugates of histo-blood group (A di, A tri, B di, B tri, H di, SiaLe a, and SiaLe x) to human polymorphonuclear leukocytes (PMNs), and effects on H 2O 2 generation elicited by different agonists such as digitonin, N-formyl-Met-Leu-Phe (FMLP) and the galactoside-specific lectin from Viscum album L. (VAA) were assessed. PMNs expressed binding sites for blood group-related neoglycoconjugates in the range of N10 6–10 7/cell with KD-values in the μM range. Treatment of PMNs (2×10 6 cells/ml) with PAA-probes (50 μg/ml) for 5 min did not activate the “respiratory burst”. However, it led to suppression (range 20–70%) of H 2O 2 generation of cells in the presence of elicitors. In detail, the FMLP-induced response was significantly decreased by A di, A tri, B tri, H di, SiaLe a, and SiaLe x conjugates, whereas for digitonin one only by A di, A tri, B tri. All the seven tested PAA-probes were found to inhibit significantly VAA-mediated release of H 2O 2 from PMNs. In this case, interference can take place already, at the stage of initial binding, especially for B- and H-epitopes, but less prominently for A- and SiaLe-epitopes. These results support the notion that PAA-immobilized histo-blood group oligosaccharides can serve as effector molecules with the ability to reduce the H 2O 2-generation of PMNs, warranting further studies on the involved reaction pathway. 相似文献
10.
3-[3-(Piperidinomethyl)phenoxy]alkyl, N-cyano- N′-[ω-[3-(1-piperidinylmethyl)phenoxy]alkyl]guanidine and 2-(5-methyl-4-imidazolyl)methyl thioethyl derivatives containing fluorescent functionalities were synthesized and the histamine H 2 receptor affinity was evaluated using the H 2 antagonist [ 125I]-aminopotentidine. The compounds exhibited weak to potent H 2 receptor affinity with p Ki values ranging from <4 to 8.85. The highest H 2 receptor affinity was observed for N-cyano- N′-[ω-[3-(1-piperidinylmethyl)phenoxy]alkyl]guanidines substituted with methylanthranilate (13), cyanoindolizine (6) and cyanoisoindole (11) moieties via an ethyl or propyl linker. 相似文献
11.
Five heterometallic compounds with formulae [Ba(H 2O) 4Cr 2(μ-OH) 2( nta) 2] · 3H 2O (I), [M( bpy) 2(H 2O) 2] [Cr 2(OH) 2( nta) 2] · 7H 2O, where M 2+ = Zn, (II); Ni, (III); Co, (IV) and [Mn(H 2O) 3( bpy)Cr 2(OH) 2( nta) 2] · ( bpy) · 5H 2O (V); bpy = 2,2′-bipyridine, ( nta = nitrilotriacetate ion) have been prepared by reaction of I with the corresponding M II-sulfates in the presence of 2,2′-bipyridine. Substances I–V have been characterized by magnetic susceptibility measurements, EPR and X-ray determinations. I represents a 2D coordination polymer formed by coordination of centrosymmetrical dimeric chromium(III) units and Barium cations. The 10-coordinate Ba polyhedron is completed by four water molecules. Compounds II–IV are isostructural and consist of non-centrosymmetric dimeric anions [Cr 2(μ-OH) 2( nta) 2] 2−, complex cations [M II( bpy) 2(H 2O) 2] 2+ and solvate water molecules. The octahedral coordination of chromium atoms implies four donor atoms of the nta3− ligands and two bridging OH groups. Multiple hydrogen bonds of coordinated and solvate water molecules link anions and cations in a 3D network. A similar [Cr 2(μ-OH) 2( nta) 2] 2− unit is found in V. The bridging function is performed by a carboxylate oxygen atom of the nta ligand that leads to the formation of a trinuclear complex [Mn( bpy)(H 2O) 2Cr 2(μ-OH) 2( nta) 2]. Experimental and calculated frequency and temperature dependences of EPR spectra of these compounds are presented. The fine structure appearing on the EPR spectra of compound V is analyzed in detail at different temperatures. It is established that the main part of the EPR signals is due to the transitions in the spin states of a spin multiplet with S = 2. Analyses of experimental and calculated spectra confirm the absence of interaction between metal ions (M II) and Cr-dimers in complexes III and IV and the presence of weak Mn–Cr interactions in V. The temperature dependence of magnetic susceptibilities for I–V was fitted on the basis of the expression derived from isotropic Hamiltonian including a bi-quadratic exchange term. 相似文献
12.
[Ru II(Me 2edda)(H 2O) 2] (1), Me 2edda 2− = N, N′-dimethylethylenediaminediacetate, exhibits a sterically-controlled molecular recognition in forming η 2 and η 4 olefin complexes. 1 exists with an N 2O 2 in-plane set of chelate donors and axial H 2O ligands. The two CH 3 functionalities of Me 2edda 2− are poised above and below the N 2O 2 plane of the glycinato rings. Studies herein of the 2,2′-bipyridine complex, [Ru II(Me 2edda)(bpy)], with bidentate bpy chelation as established via 1H NMR and electrochemical methods show 1 to be ligated in the S,S configuration with the glycinato rings in-plane as a cis-O form. 1 is sterically discriminating in forming η 2 complexes with smaller olefins (ethylene, 2-propene, cis-2-butene, methyl vinyl ketone and 3-cyclohexene-1-methanol), but rejects larger decorated ring structures and branched olefins (1,2-dimethyluracil, cyclohexene-1-one 2-methyl-2-propene). η 2 complexes of 1 have characteristic Ru II/III DPP waves near 0.55 V which vary slightly with olefin structure. Potentially bidendate dienes (1,3-butadiene, 1,3-cyclohexadiene and 2,5-norbornadiene (nbd) form η 4 complexes as shown by Ru II/III waves between 0.94 and 1.30 V, indicate of a highly stabilized Ru II center by π-backboning. An η 2η 4 ‘equilibrium’ with apparent K = 22 at 25 °C is observed for nbd coordinated to 1. (The η 2 and η 4 distribution may be a kinetic one and not a thermodynamic one). To allow formation of the cis η 4 complexes, 1 must undergo a shift of one or both glycinato donors from the N 2O 2 plane into the axial site away from the dimethyl functionalities. η 4 chelation by 1,3-butadiene has been confirmed by 1H NMR spectral assignments of two [Ru II(Me 2edda)] isomers, one in the axial rans-O glycinato configuration, e.g. 1,3-butadiene is bidentate in the original N 2O 2 plane and a second unsymmetrical glycinato arrangement with in-plane and axial glycinato as well as in-plane and axial η 4-1,3-butadiene coordination. [Ru II(hedta)(H 2O)] − (2), hedta 3− = N-hydrpxyethylenediaminetriacetate, is less discriminating for olefin structures, forming η 2 complexes with all eleven olefins and dienes mentioned for studies with 1. However, 2 does not undergo displacement of a carboxylate donor by the second olefin unit of a diene [Ru II(hedta)(diene)] − complexes possess a pendant non-coordinated olefin and on η 2-bound olefin in the complex, indicated by a normal Ru II(pac)(olefin)Ru II/III wave near 0.55 V. 相似文献
13.
Hydrogen peroxide, produced by inflammatory and vascular cells, induces oxidative stress that may contribute to endothelial dysfunction. In smooth muscle cells, H 2O 2 induces production of O 2− by activating NADPH oxidase. However, the mechanisms whereby H 2O 2 induces oxidative stress in endothelial cells are poorly understood. We examined the effects of H 2O 2 on O 2− levels on porcine aortic endothelial cells (PAEC). Treatment with 60 μmol/L H 2O 2 markedly increased intracellular O 2− levels (determined by conversion of dihydroethidium to hydroxyethidium) and produced cytotoxicity (determined by propidium iodide staining) in PAEC. Overexpression of human manganese superoxide dismutase in PAEC reduced O 2− levels and attenuated cytotoxicity resulting from treatment with H 2O 2. L-NAME, an inhibitor of nitric oxide synthase (NOS), and apocynin, an inhibitor of NADPH oxidase, reduced O 2− levels in PAEC treated with H 2O 2, suggesting that both NOS and NADPH oxidase contribute to H 2O 2-induced O 2− in PAEC. Inhibition of NADPH oxidase using apocynin and NOS rescue with L-sepiapterin together reduced O 2− levels in PAEC treated with H 2O 2 to control levels. This suggests interaction-distinct NOS and NADPH oxidase pathways to superoxide. We conclude that H 2O 2 produces oxidative stress in endothelial cells by increasing intracellular O 2− levels through NOS and NADPH oxidase. These findings suggest a complex interaction between H 2O 2 and oxidant-generating enzymes that may contribute to endothelial dysfunction. 相似文献
14.
The hydrothermal reactions of (Ph 4P)[VO 2Cl 2] and H 2C 2O 4 at 150 and 125°C yield (Ph 4P) 2[V 2O 2(H 2O) 2(C 2O 4) 3]·4H 2O (1) and (Ph 4P)[VOCl(C 2O 4)] (2), respectively. The structure of the molecular anion of 1 consists of a binuclear unit of oxovanadium(IV) octahedra bridged by a bisbidentate oxalate group. The VO 6 coordination geometry at each vanadium site is defined by a terminal oxo group, an aquo ligand, and four oxygen donors — two from the bisbidentate bridging oxalate and two from the terminal bidentate oxalate. The structure of 2 consists of discrete Ph 4P + cations occupying regions between [VOCl(C 2O 4)] −∞ spiral chains. The structure of the one-dimensional anionic chain exhibits V(IV) octahedra bridged by bisbidentate oxalate groups. Crystal data: 1·4H 2O, monoclinic P2 1/ n, A = 12.694(3), B = 12.531(3), C = 17.17(3) Å, β = 106.32(2)°, V = 2621.3(13) Å 3, Z = 2, Dcalc = 1.501 g cm −3, structure solution and refinement converged at a conventional residual of 0.0518; 2, tetragonal P4 3, A = 12.145(2), C = 15.991(3) Å, V = 2358.7(12) Å 3, Z = 4, R = 0.0452. 相似文献
15.
A number of N, N′-bis(4-substituted phenyl)-1,7-diaza-12-crown-4 and N, N′-bis(4-substituted phenyl)-1, 10-diaza-18-crown-6 (where the substituents are OCH 3, CH 3, H, Cl, respectively) have been prepared by cyclization reaction of a ditosylate with the appropriately substituted diol. These new macrocyclic ligands have been characterized by means of elemental analysis, IR, 1H NMR and MS spectra. The crystal structures of N, N′-bis(4-chlorophenyl)-1,10-diaza-18-crown-6 (21) and its complex with barium thiocyanate Ba(SCN) 2 (22) have been determined by single crystal X-ray diffraction. The crystallographic data are as follows: 21: C 24H 32Cl 2N 2O 4, orthorhombic, P2 12 12 1, A=4.852(1), B=11.989(2), C=41.231(8) Å, V=2398.7(8) Å 3, Z=4; 22: C 26H 32Cl 2N 4O 4S 2Ba, monoclinic, P2 1/ c, A=8.801(2), B=11.653(9), C=15.756(6) Å, ß=105.96(3)°, V=1553.7(14) Å 3, Z=2. In the complex, the Ba atom is eight-coordinate (O(1), O(2), O(1)′, O(2)′, N(1), N(1)′, N(21), N(21)′) to form a distorted D6h geometry with the Ba atom at the center of crystallographic symmetry. 相似文献
16.
Electron spin resonance spin trapping was utilized to investigate free radical generation from cobalt (Co) mediated reactions using 5,5-dimethyl-l-pyrroline (DMPO) as a spin trap. A mixture of Co with water in the presence of DMPO generated 5,5-dimethylpyrroline-(2)-oxy(1) DMPOX, indicating the production of strong oxidants. Addition of superoxide dismutase (SOD) to the mixture produced hydroxyl radical ( OH). Catalase eliminated the generation of this radical and metal chelators, such as desferoxamine, diethylenetriaminepentaacetic acid or 1,10-phenanthroline, decreased it. Addition of Fe(II) resulted in a several fold increase in the OH generation. UV and O 2 consumption measurements showed that the reaction of Co with water consumed molecular oxygen and generated Co(II). Since reaction of Co(II) with H 2O 2 did not generate any significant amount of OH radicals, a Co(I) mediated Fenton-like reaction [Co(I) + H 2O 2 → Co(II) + OH + OH −] seems responsible for OH generation. H 2O 2 is produced from O 2− via dismutation. O 2− is produced by one-electron reduction of molecular oxygen catalyzed by Co. Chelation of Co(II) by biological chelators, such as glutathione or β-ananyl-3-methyl-
-histidine alters, its oxidation–reduction potential and makes Co(II) capable of generating OH via a Co(II)-mediated Fenton-like reaction [Co(II) + H 2O 2 → Co(III) + OH + OH −]. Thus, the reaction of Co with water, especially in the presence of biological chelators, glutathione, glycylglycylhistidine and β-ananyl-3-methyl-
-histidine, is capable of generating a whole spectrum of reactive oxygen species, which may be responsible for Co-induced cell injury. 相似文献
17.
The molecular structure of the title complexes [Fe(H 2O) 4][Fe(Hedta)(H 2O)] 2 · 4H 2O (I) and [Fe(H[ 2edta)(H 2O)] · 2H 2O (II) have been determined by single-crystal X-ray analyses. The crystal data are as follows: I: monoclinic, P2 1/ n, A = 11.794(2), B = 15.990(2), C = 9.206(2) Å, β = 90.33(1)°, V = 1736.1(5) Å 3, Z = 2 and R = 0.030; II: monoclinic, C2/ c, A = 11.074(2), B = 9.856(2), C = 14.399(2) Å, β = 95.86(1)°, V = 1563.3(4) Å 3, Z = 4 and R = 0.025. I is found to be isomorphous with the Mn II analog reported earlier and to contain a seven-coordinate and approximately pentagonal-bipyramidal (PB) [Fe II(Hedta)(H 2O] − unit in which Hedta acts as a hexadentate ligand. The [Fe II(H 2edta)(H 2O)] unit in II has also a seven-coordinate PB structure with the two protonated equatorial glycine arms both remaining coordinated, and thus bears a structural resemblance to the seven-coordinate [Co II(H 2edta)(H 2O)] reported previously. 相似文献
18.
New polydentate open structure ligands H 3L1 and H 3L2 were synthesized by the condensation of 2,6-diformyl-4- tert-butylphenol and corresponding N-R- o-phenylenediamines (R = Ac and R = Boc). Treating of the ligands with copper trimethylacetate leads to binuclear copper complexes with dissimilar Cu 2O 2 cores, the structures of which were solved by X-ray diffraction analysis. The electrochemical properties of both complexes were studied; the observed redox transitions were assigned to specific redox-active sites of the molecule. These assignments were confirmed by DFT calculations of the electronic structure of binuclear complexes. Both complexes exhibit antiferromagnetic behaviour, as confirmed by variable-temperature magnetic studies. 相似文献
19.
1. Single reduced methyl viologen (MV .+) acts as an electron donor in a number of enzyme systems. The large changes in extinction coefficient upon oxidation (λ max 600 nm; MV .+, = 1.3 · 10 4 M −1 · cm −1; oxidised form of methyl viologen (MV 2+), = 0.0) make it ideally suited to kinetic studies of electron transfer reactions using stopped-flow and standard spectrophotometric techniques. 2. A convenient electrochemical preparation of large amounts of MV.+ has been developed. 3. A commercial stopped-flow apparatus was modified in order to obtain a high degree of anaerobicity. 4. The reaction of MV.+ with O2 produced H2O2 (k > 5 · 106 M−1 · s−1, pH 7.5, 25 °C). H2O2 subsequently reacted with excess MV.+ (k = 2.3 · 103 M−1 · s−1, pH 7.5, 25 °C) to produce water. The kinetics of this reaction were complex and have only been interpreted over a limited range of concentrations. 5. The results support the theory that the herbicidal action of methyl viologen (Paraquat, Gramoxone) is due to H2O2 (or radicals derived from H2O2) induced damage of plant cell membrane. 相似文献
20.
The reaction of N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (tpen) with VCl 3 in CH 3CN yields Cl 3V(tpen)VCl 3 which was hydrolyzed in water in the presence of oxygen affording [V 2O 2(μ-OH) 2(tpen)]I 2·2H 2O, the crystal structure of which has been determined. A syn-{OV(μ-OH) 2VO} 2+ core has been identified where the V(IV) centers are antiferromagnetically coupled ( J = −150 cm −1; g = 1.80). 相似文献
|