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1.
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
2.
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
3.
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
4.
The reaction of RuCl 3(H 2O), with C 5Me 4CF 3J in refluxing EtOH gives [Ru 2(η 5-C 5Me 1CF 2) 2 (μ-Cl 2] (20 in 44% yield. Dimer 2 antiferromagnetic (−2 J=200 cm 1). The crystal structures of 2 (rhombohedral system, R3 space group, Z=9, R=0.0589) and [Rh 2(η 5-C 5Me 4CF 3( 2Cl 2(μ-Cl) 2] (3) (rhombohedral system.
space group, Z = 9, R = 0.0641) were solved; both complexes have dimeric structures with a trans arrangement of the η 5-C 5Me 4CF 4 rings. Comparison of the geometry of 2 and 3 with those of the corresponding η 5-C 5Me 5 complexes shows that lowering the ring symmetry causes significant distortion of the M 2(μ-Cl) 2 moiety. The analysis of the MCl 3 fragment conformations in 2 and 3 and in the η 5-C 5ME 5 analogues shows that they are correlated with the M---M distances. The Cl atoms are displaced by Br on reaction of 2 with KBr in MeOH to give the diamagnetic dimer [Ru 2(η 5-C 5Me 4CF 3) 2Br 2 (μ-Br 2] (4). Complex 2 reacts with O 2 in CH 2Cl 2 solution at ambient temperature to form a mixture of isomeric η 6-fulvene dimers [Ru 2(η 6-C 5Me 3CF 3 = CH 2) 2Cl 2(μ-Cl) 2] (5). Reactions of 5 with CO and allyl chloride give Ru(η 5-C 5Me 3CF 3CH 2Cl)(CO) 2Cl (6) and Ru(η 5-C 5Me 3CF 3CF 3CH 2Cl)(η 3-C 3H 5)Cl 2 (7) respectively. 相似文献
5.
The syntheses and structures of [Ni(H 2O) 6] 2+[MF 6] 2− (M = Ti,Zr,Hf) and Ni 3(py) 12F 6·7H 2O are reported. The former three compounds are isostructural, crystallizing in the trigonal space group
(No. 148) with Z = 3. The lattice parameters are a = 9.489(4), C = 9.764(7) Å, with V = 761(1) Å 3 for Ti; a = 9.727(2), C = 10.051(3) Å, with V = 823.6(6) Å 3 for Zr; and a = 9.724(3), C = 10.028(4)Å, with V = 821.2(8)Å 3 for Hf. The structures consist of discrete [Ni(H 2O) 6] 2+ and [MF 6] 2− octahedra joined by O---HF hydrogen bond Large single crystals were grown in an aqueous hydrofluoric acid solution. Ni 3(py) 12F 6·7H 2O crystallizes in the monoclinic space group I2/ a (No. 15) with Z = 4. The lattice parameters are a = 16.117(4), B = 8.529(3), C = 46.220(7) Å, β = 92.46(2)°, and V = 6348(5) Å 3. The structure consists of discrete Ni(py) 4F 2 octahedra linked through H---O---HF and H---O---HO hydrogen bonding interactions. Single c were grown from a (HF) x·pyridine/pyridine/water solution. 相似文献
6.
[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
7.
The positive ion electrospray mass spectrometry (ESI-MS) of trans-[Ru(NO)Cl)(dpaH) 2]Cl 2 (dpaH=2,2′-dipyridylamine), obtained from the carrier solvent of H 2O–CH 3OH (50:50), revealed 1+ ions of the formulas [Ru II(NO +)Cl(dpaH)(dpa)] + ( m/ z=508), [Ru IIICl(dpaH)(dpa −)] + ( m/ z=478), [Ru II(NO +)(dpa) 2] + ( m/ z=472), [Ru III(dpa) 2] + ( m/ z=442), originating from proton dissociation from the parent [Ru II(NO +)Cl(dpaH) 2] 2+ ion with subsequent loss of NO (17.4% of dissociative events) or loss of HCl (82.6% of dissociative events). Further loss of NO from the m/ z=472 fragment yields the m/ z=442 fragment. Thus, ionization of the NH moiety of dpaH is a significant factor in controlling the net ionic charge in the gas phase, and allowing preferential dissociation of HCl in the fragmentation processes. With NaCl added, an ion pair, {Na[Ru II(NO)Cl(dpa) 2]} + ( m/ z=530; 532), is detectable. All these positive mass peaks that contain Ru carry a signature ‘handprint’ of adjacent m/ z peaks due to the isotopic distribution of 104Ru, 102Ru, 101Ru, 99Ru, 98Ru and 96Ru mass centered around 101Ru for each fragment, and have been matched to the theoretical isotopic distribution for each set of peaks centered on the main isotope peak. When the starting complex is allowed to undergo aquation for two weeks in H 2O, loss of the axial Cl − is shown by the approximately 77% attenuation of the [Ru II(NO +)Cl(dpaH)(dpa)] + ion, being replaced by the [Ru II(NO +)(H 2O)(dpa) 2] + ( m/ z=490) as the most abundant high-mass species. Loss of H 2O is observed to form [Ru II(NO +)(dpa) 2] + ( m/ z=472). No positive ion mass spectral peaks were observed for RuCl 3(NO)(H 2O) 2, ‘caged NO’. Negative ions were observed by proton dissociation forming [Ru II(NO)Cl 3(H 2O)(OH)] − in the ionization chamber, detecting the parent 1− ion at m/ z=274, followed by the loss of NO as the main dissociative pathway that produces [Ru IIICl 3(H 2O)(OH)] − ( m/ z=244). This species undergoes reductive elimination of a chlorine atom, forming [Ru IICl 2(H 2O)(OH)] − ( m/ z=208). The ease of the NO dissociation is increased for the negative ions, which should be more able to stabilize a Ru III product upon NO loss. 相似文献
8.
The phosphinoalkenes Ph 2P(CH 2) nCH=CH 2 ( n= 1, 2, 3) and phosphinoalkynes Ph 2P(CH 2) n C≡CR (R = H, N = 2, 3; R = CH 3, N = 1) have been prepared and reacted with the dirhodium complex (η−C 5H 5) 2Rh 2(μ−CO) (μ−η 2−CF 3C 2CF 3). Six new complexes of the type (ν−C 5H 5) 2(Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3)L, where L is a P-coordinated phosphinoalkene, or phosphinoalkyne have been isolated and fully characterized; the carbonyl and phosphine ligands are predominantly trans on the Rh---Rh bond, but there is spectroscopic evidence that a small amount of the cis-isomer is formed also. Treatment of the dirhodium-phosphinoalkene complexes with (η−CH 3C 5H 4)Mn(CO) 2thf resulted in coordination of the manganese to the alkene function. The Rh 2---Mn complex [(η−C 5H 5) 2Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3) {Ph 2P(CH 2) 3CH=CH 2} (η−CH 3C 5H 4)Mn(CO) 2] was fully characterized. Simi treatment of the dirhodium-phosphinoalkyne complexes with Co 2(CO) 8 resulted in the coordination of Co 2(CO) 6 to the alkyne function. The Rh 2---Co 2 complex [(η−C 5H 5) 2Rh 2(CO) (μ−η 1:η 1−CF 3C 2CF 3) {Ph 2PCH 2C≡CCH 3}Co 2(CO) 2], C 37H 25Co 2F 6O 7PRh 2, was fully characteriz spectroscopically, and the molecular structure of this complex was determined by a single crystal X-ray diffraction study. It is triclinic, space group
( Ci1, No. 2) with a = 18.454(6), B = 11.418(3), C = 10.124(3) Å, = 112.16(2), β = 102.34(3), γ = 91.62(3)°, Z = 2. Conventional R on | F| was 0.052 fo observed ( I > 3σ( I)) reflections. The Rh 2 and Co 2 parts of the molecule are distinct, the carbonyl and phosphine are mutually trans on the Rh---Rh bond, and the orientations of the alkynes are parallel for Rh 2 and perpendicular for Co 2. Attempts to induce Rh 2Co 2 cluster formation were unsuccessful. 相似文献
9.
The cationic monoalkylated derivatives of the well-known metalloligand [Pt 2(μ-S) 2(PPh 3) 4], viz. [Pt 2(μ-S)(μ-SR)(PPh 3) 4] + (R = n-Bu, CH 2Ph) are themselves able to act as metalloligands towards the Ph 3PAu + and R′Hg + (R′ = Ph or ferrocenyl) fragments, by reaction with Ph 3PAuCl or R′HgCl, respectively. The resulting dicationic products [Pt 2(μ-SR)(μ-SAuPPh 3)(PPh 3) 4] 2+ and [Pt 2(μ-SR)(μ-SHgR′)(PPh 3) 4] 2+ are readily isolated as their hexafluorophosphate salts, and have been fully characterised by spectroscopic techniques and an X-ray structure determination on [Pt 2(μ-SR)(μ-SHgFc)(PPh 3) 4](PF 6) 2. 相似文献
10.
The turning point between apoptosis and necrosis induced by hydrogen peroxide (H 2O 2) have been investigated using human T-lymphoma Jurkat cells. Cells treated with 50 μM H 2O 2 exhibited caspase-9 and caspase-3 activation, finally leading to apoptotic cell death. Treatment with 500 μM H 2O 2 did not exhibit caspase activation and changed the mode of death to necrosis. On the other hand, the release of cytochrome c from the mitochondria was observed under both conditions. Treatment with 500 μM H 2O 2, but not with 50 μM H 2O 2, caused a marked decrease in the intracellular ATP level; this is essential for apoptosome formation. H 2O 2-reducing enzymes such as cellular glutathione peroxidase (cGPx) and catalase, which are important for the activation of caspases, were active under the 500 μM H 2O 2 condition. Prevention of intracellular ATP loss, which did not influence cytochrome c release, significantly activated caspases, changing the mode of cell death from necrosis to apoptosis. These results suggest that ATP-dependent apoptosome formation determines whether H 2O 2-induced cell death is due to apoptosis or necrosis. 相似文献
11.
The reaction of [N(PPh 3) 2] 2[Ni 6(CO) 12] with Cu(PPh 3) xCl ( x=1, 2), as well as the degradation of [N(PPh 3) 2] 2[H 2Ni 12(CO) 21] with PPh 3, affords the new and unstable dark orange–brown [N(PPh 3) 2] 2[Ni 9(CO) 16].THF salt in low yields. This salt has been characterized by a CCD X-ray diffraction determination, along with IR spectroscopy and elemental analysis. The close-packed two-layer metal core geometry of the [Ni 9(CO) 16] 2− dianion is directly related to that of the bimetallic [Ni 6Rh 3(CO) 17] 3− trianion and may be envisioned to be formally derived from the hcp three-layer geometry of [Ni 12(CO) 21] 4− by the substitution of one of the two outer [Ni 3(CO) 3(μ−CO) 3] 2− layers with a face-bridging carbonyl group. 相似文献
12.
The Pt 2 (II) isomeric terminal hydrides [(CO)(H)Pt(μ-PBu t 2) 2Pt(PBu t 2H)]CF 3SO 3 (1a), and [(CO)Pt(μ-PBu t 2) 2Pt(PBu t 2H)(H)]CF 3SO 3 (1b), react rapidly with 1 atm of carbon monoxide to give the same mixture of two isomers of the Pt 2 (I) dicarbonyl [Pt 2(μ-PBu t 2)(CO) 2(PBu t 2H) 2]CF 3SO 3 (3-Pt); the solid state structure of the isomer bearing the carbonyl ligands pseudo- trans to the bridging phosphide was solved by X-ray diffraction. A remarkable difference was instead found between the reactivity of 1a and 1b towards carbon disulfide or isoprene. In both cases 1b reacts slowly to afford [Pt 2(μ-PBu t 2)(μ,η 2,η 2-CS 2)(PBu t 2H) 2]CF 3SO 3 (4-Pt), and [Pt 2(μ-PBu t 2)(μ,η 2,η 2-isoprene) (PBu t 2H) 2]CF 3SO 3 (6-Pt), respectively. In the same experimental conditions, 1a is totally inert. A common mechanism, proceeding through the preassociation of the incoming ligand followed by the P---H bond formation between one of the bridging P atoms and the hydride ligand, has been suggested for these reactions. 相似文献
13.
The binuclear cyanoferrate, tetraphenylphosphonium pentacyanoiron(III)-μ-cyano-amminetetracyanoiron(III), [(C 6H 5) 4P] 4[Fe 2(CN) 10NH 3] 4−, was synthesized by air oxidation of aqueous solutions of Na 3[Fe(CN) 5NH 3] · 3H 2O. Single crystal X-ray diffraction studies show the compound to contain the binuclear, cyano-bridged anion, [(NC) 5Fe---NC---Fe(CN) 4NH 3] 4−. This compound is structurally identical to the one prepared by A. Ludi et al., [Inorg. Chim. Acta, 34, 113 (1979)], with the exception that [Fe(CN) 6] 3− is not required for the synthesis of this compound. The Fe(III) atoms are antiferromagnetically coupled through the CN − bridge, as shown by a maximum in the magnetic susceptibility at 50 K. The electronic and IR spectra of the complex in the solid state and in solution are discussed. 相似文献
14.
Metathesis of [(η 3:η 3−C 10H 16)Ru(Cl) (μ−Cl)] 2 (1) with [R 3P) (Cl)M(μ-Cl)] 2 (M = Pd, Pt), [Me 2NCH 2C 6H 4Pd(μ-Cl)] 2 and [(OC) 2Rh(μ-Cl)] 2 affords the heterobimetallic chloro bridged complexes (η 3:η 3-C 10H 16) (Cl)Ru(μ-Cl) 2M(PR 3)(Cl) (M = Pd, Pt), (η 3:η 3-C 10H 16) (Cl)Ru(μ-Cl) 2PdC 6H 4CH 2NMe 2 and (η 3:η 3-C 10H 16) (Cl)Ru(μ-Cl) 2Rh(CO) 2, respectively. Complex 1 reacts with [Cp *M(Cl) (μ-Cl)] 2 (M = Rh, Ir), [ p-cymene Ru(Cl) (μ-Cl] 2 and [(Cy 3P)Cu(μ-Cl)] 2 to give an equilibrium of the heterobimetallic complexes and of educts. The structures of (η 3:η 3-C 10H 16)Ru(μ-Cl) 2Pd(PR 3) (Cl) ( R = Et, Bu) and of one diastereoisomer of (η 3:η 3-C 10H 16)Ru(μ-Cl) 2IrCp *(Cl) were determined by X-ray diffraction. 相似文献
15.
The reactions of [(H 5C 6) 3P] 2ReH 6− with (CH 3CN) 3Cr(CO) 3, (diglyme)Mo(CO) 3 or (C 3H 7CN) 3W(CO) 3 led to the formation of [(H 5C 6) 3P] 2ReH 6M(CO) 3− (M = Cr, Mo, W) complexes. These have been characterized by IR and NMR spectroscopies, as well as elemental analyses. A single crystal X-ray diffraction study has also been carried out for the M = Cr complex as a K(18-crown-6) + salt. The complex crystallizes as a THF monosolvate in the monoclinic space group P2 1/ n with a = 22.323(6), B = 9.523(2), C = 27.502(5) Å, β = 104.98(2) 0 and V = 5648 Å 3 for Z = 4. The Re---Cr separation is 2.5745(12) Å, and the two phosphine ligands are oriented unsymmetrically. Although the hydride ligands were not found, the presence of three bridging hydrides and a dodecahedral coordination geometry about rhenium could be inferred. Low temperature 1H and 31P NMR spectroscopic studies did not reveal the low symmetry of the solid state structure. 相似文献
16.
The trinuclear clusters [Pd 3(μ-dppm) 3(CO)] 2+ and [PtPdCo(μ-dppm) 2(CO) 3(CN tBu)] + exhibit a large and a small cavity, respectively, formed by the phenyl rings of the bridging diphosphine ligands. Their binding constants ( K11) with halide ions (X −) were obtained by UV-Vis spectroscopy. The binding ability varies as I − > Br − > Cl −, and [Pd 3(μ-dppm) 3(CO)] 2+ > [ptPdCo(μ-dppm) 2-(CO) 3(CN tBu)] +. The MO diagram for the related cluster [Pd 2Co(μ-dppm) 2(CO) 4] + has been addressed theoretically in order to predict the nature of the lowest energy electronic bands. For this class of compounds, the lowest energy bands are assigned to charge transfers from the Co center to the Pd 2 centers. 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.
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
19.
New mixed metal complexes SrCu 2(O 2CR) 3(bdmap) 3 (R = CF 3 (1a), CH 3 (1b)) and a new dinuclear bismuth complex Bi 2(O 2CCH 3) 4(bdmap) 2(H 2O) (2) have been synthesized. Their crystal structures have been determined by single-crystal X-ray diffraction analyses. Thermal decomposition behaviors of these complexes have been examined by TGA and X-ray powder diffraction analyses. While compound 1a decomposes to SrF 2 and CuO at about 380°C, compound 1b decomposes to the corresponding oxides above 800°C. Compound 2 decomposes cleanly to Bi 2O 3 at 330°C. The magnetism of 1a was examined by the measurement of susceptibility from 5–300 K. Theoretical fitting for the susceptibility data revealed that 1a is an antiferromagnetically coupled system with g = 2.012(7), −2 J = 34.0(8) cm −1. Crystal data for 1a: C 27H 51N 6O 9F 9Cu 2Sr/THF, monoclinic space group P2 1/ m, A = 10.708(6), B = 15.20(1), C = 15.404(7) Å, β = 107.94(4)°, V = 2386(2) Å 3, Z = 2; for 1b: C 27H 60N 6O 9Cu 2Sr/THF, orthorhombic space group Pbcn, A = 19.164(9), B = 26.829(8), C = 17.240(9) Å, V = 8864(5) Å 3, Z = 8; for 2: C 22H 48O 11N 4Bi 2, monoclinic space group P2 1/ c, A = 17.614(9), B = 10.741(3), C = 18.910(7) Å, β = 109.99(3)°, V = 3362(2) Å 3, Z = 4. 相似文献
20.
Tea ( Camellia sinensis) catechins have been studied for disease prevention. These compounds undergo oxidation and produce H 2O 2. We have previously shown that holding tea solution or chewing tea leaves generates high salivary catechin levels. Herein, we examined the generation of H 2O 2 in the oral cavity by green tea solution or leaves. Human volunteers holding green tea solution (0.1-0.6%) developed salivary H 2O 2 with C max = 2.9-9.6 μM and AUC 0 → ∞ = 8.5-285.3 μM min. Chewing 2 g green tea leaves produced higher levels of H 2O 2 (C max = 31.2 μM, AUC 0 → ∞ = 1290.9 μM min). Salivary H 2O 2 correlated with catechin levels and with predicted levels of H 2O 2 (C max(expected) = 36 μM vs C max(determined) = 31.2 μM). Salivary H 2O 2 and catechin concentrations were similar to those that are biologically active in vitro. Catechin-generated H 2O 2 may, therefore, have a role in disease prevention by green tea. 相似文献
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