共查询到20条相似文献,搜索用时 15 毫秒
1.
Martin G. O’Toole Majda Kreso Pawel M. Kozlowski Mark S. Mashuta Craig A. Grapperhaus 《Journal of biological inorganic chemistry》2008,13(8):1219-1230
The oxygen sensitivity of two related iron(III) dithiolate complexes of the ligand [4,7-bis-(2′-methyl-2′-mercatopropyl)-1-thia-4,7-diazacyclononane],
(bmmp-TASN)FeCN (1) and (bmmp-TASN)FeCl (2), has been examined. Oxygen exposure of the low-spin complex 1 yields the disulfonate complex (bmmp-O6-TASN)FeCN (3) as an olive-green solid with characteristic peaks in the IR spectrum at 1262, 1221, 1111, 1021, 947, 800, and 477 cm−1. The corresponding nickel dithiolate, (bmmp-TASN)Ni (4), yields the related disulfonato derivative, (bmmp-O6-TASN)Ni (5) upon addition of H2O2 (IR bands at 1258, 1143, 1106, 1012, 800, and 694 cm−1. Oxygen exposure of the high-spin complex 2 results in disulfide formation and decomplexation of the metal with subsequent iron-oxo cluster formation. Complexes 1 and 2 were examined using density functional theory calculations. A natural bond order/natural localized molecular orbital covalency
analysis reveals that the low-spin complex 1 contains Fe–Sthiolate bonds with calculated covalencies of 75 and 86%, while the high-spin complex 2 contains Fe–Sthiolate bonds with calculated covalencies of 11 and 40%. The results indicate the degree of covalency of the Fe–S bonds plays a major
role in determining the reaction pathway associated with oxygen exposure of iron thiolates. The X-ray structures of 1, 4, and 5 are reported.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
2.
The effect of iron on ferritin turnover in rat liver 总被引:1,自引:0,他引:1
125I-labelled angiotensin II (A II) specifically binds to solubilized receptors extracted from rat isolated glomeruli using CHAPS (3-[3-( cholamidopropyl ) dimethylammonio ]-1-propanesulfonate). The yield of solubilization of the binding sites was 3.3%. Equilibrium was reached after 15-20 min and specific binding represented 75% of total binding. Dissociation of the hormone-receptor complex after addition of an excess of A II was very slow in the presence of Ca2+ and Mg2+. [Sar1 Ala8] A II and [Sar1 Ile8] A II were more potent as competitive inhibitors of 125I-labelled A II than A II itself and its heptapeptide. These basic features of 125I-labelled A II binding to the extracted material were similar to those observed previously with untreated glomeruli. 相似文献
3.
Heather N. Yeowell James R. White 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,797(3):302-311
Uptake studies with [14C]picolinate and 55Fe3+ have provided an explanation for the change in streptonigrin killing on adaptation of Escherichia coli to picolinate, in terms of the available iron within the cell. When picolinic acid is added to a growing culture of E. coli an interval of bacteriostasis ensues; this adaptation period is followed by resumption of exponential growth. Addition of picolinate (4 mM) to a log phase culture of strain W3110 gave protection from the lethal action of streptonigrin (30 μM) when the two agents were added simultaneously. In contrast streptonigrin killed cells that had adapted to picolinate; however, a preincubation of adapted W3110 with phenethyl alcohol protected the cells from streptonigrin lethality. [14C]Picolinate uptake studies showed that initially picolinate entered the cells, but that it was excluded from adapted cells; addition of phenethyl alcohol permitted the entry of picolinate into adapted W3110. The changes in streptonigrin killing parallel the changes in concentration of intracellular picolinate, which can chelate the iron required by streptonigrin for its bactericidal action. 55Fe3+ uptake studies showed that initially picolinate prevented iron accumulation by strain W3110, whereas adapted cells did take up iron in the presence of picolinate. Addition of phenethyl alcohol prevented any observed uptake of iron by adapted W3110. This modulation of iron transport by picolinate also affects streptonigrin lethality. Experiments with iron transport mutants showed that picolinate acted on both the enterochelin and citrate routes of uptake. Therefore picolinate affects the concentration of available iron within the cell both by (a) its intracellular presence resulting in chelation of iron and (b) its action on iron uptake; these effects explain the change in streptonigrin killing on adaptation of E. coli to picolinate. 相似文献
4.
Optically pure C1- and C2-terpyridine ligands (L) form cobalt(II) and iron(II) complexes of formula [Co(L)Cl2] and [Fe(L)Cl2], respectively, and Iron(III) complexes of formulas [Fe(L)Cl3]. Structures of three new chiral cobalt(II) and one iron(III) complexes were analysed using X-ray crystal structure analysis. These complexes were shown to be precursor of efficient catalyst for cyclopropanation. Reaction with AgOTf converted the complex to active catalyst, which gave enantioselectivities of up to 76% ee for the trans-isomers and 83% ee for the cis-isomers of styrene cyclopropanes with ethyl diazoacetate. Hammett studies showed the active species for both cobalt and iron complexes to have a non-linear relationship to σp constant. 相似文献
5.
The reaction of chiral diphosphines with a configurationally pure cationic bis-enamide complex of iridium, bis(menthyl (Z)-α-benzamidocinnamate)-iridium tetrafluoroborate, is described. When the reactant ligand is racemic then kinetic resolution occurs with high specificity under the appropriate conditions. Since the iridium diphosphine complex is catalytically inactive in homogeneous hydrogenation, the residual enantiomer may be reacted with bis(norbornadiene)-rhodium tetrafluoroborate to produce an active catalyst. This effects the hydrogenation of methyl (Z)-α-acetamidocinnamate in optical yields comparable with those obtained separately with the enantiomerically pure ligand rhodium complex. The reaction of pure (+)- or (-)-enantiomer of bis(menthyl (Z)-α-benzamidocinnamate)-iridium tetrafluoroborate with enantiomerically pure diphosphines has been studied. Invariably one hand of the diphosphine reacts rapidly with a given enantiomer of the iridium complex to give a stable diphosphine iridium enamide complex in which the original configuration of the coordinated olefin is maintained. The other combination of enantiomers reacts much more slowly, in keeping with the kinetic resolution work, and produces an enamide complex which is unstable in solution, isomerising to a second diastereomer. Since the absolute configuration of the iridium bis-enamide complex has been established by X-ray crystallography, this experiment affords a method of determining the configuration of rhodium enamide complexes in asymmetric hydrogenation (assuming structural homology between Rh and Ir). In all cases the disfavoured enamide complex was the one involved in the catalytic pathway. 相似文献
6.
Iron storage in yeast requires the activity of the vacuolar iron transporter Ccc1. Yeast with an intact CCC1 are resistant to iron toxicity, but deletion of CCC1 renders yeast susceptible to iron toxicity. We used genetic and biochemical analysis to identify suppressors of high iron toxicity in Δccc1 cells to probe the mechanism of high iron toxicity. All genes identified as suppressors of high iron toxicity in aerobically grown Δccc1 cells encode organelle iron transporters including mitochondrial iron transporters MRS3, MRS4, and RIM2. Overexpression of MRS3 suppressed high iron toxicity by decreasing cytosolic iron through mitochondrial iron accumulation. Under anaerobic conditions, Δccc1 cells were still sensitive to high iron toxicity, but overexpression of MRS3 did not suppress iron toxicity and did not result in mitochondrial iron accumulation. We conclude that Mrs3/Mrs4 can sequester iron within mitochondria under aerobic conditions but not anaerobic conditions. We show that iron toxicity in Δccc1 cells occurred under both aerobic and anaerobic conditions. Microarray analysis showed no evidence of oxidative damage under anaerobic conditions, suggesting that iron toxicity may not be solely due to oxidative damage. Deletion of TSA1, which encodes a peroxiredoxin, exacerbated iron toxicity in Δccc1 cells under both aerobic and anaerobic conditions, suggesting a unique role for Tsa1 in iron toxicity. 相似文献
7.
Purification and partial characterization of an iron regulated outer membrane protein of B. fragilis under non-denaturing conditions 总被引:2,自引:0,他引:2
The CHAPS-PAGE gelsystem we applied gave a good separation of the proteins of Bacteroides fragilis under non-denaturing conditions. We succeeded with preparative CHAPS-PAGE in purifying an iron regulated outer membrane protein (a 44 kDa polypeptide on SDS-PAGE) of B. fragilis. This integral membrane protein proved to be a lipopolysaccharide binding protein with an isoelectric point of approximately pH 5.5. This method of purifying membrane proteins could be an important step in research into the function of membrane proteins. 相似文献
8.
Nitrite protects various organs from ischemia–reperfusion injury by ameliorating mitochondrial dysfunction. Here we provide evidence that this protection is due to the inhibition of iron-mediated oxidative reactions caused by the release of iron ions upon hypoxia. We show in a model of isolated rat liver mitochondria that upon hypoxia, mitochondria reduce nitrite to nitric oxide (NO) in amounts sufficient to inactivate redox-active iron ions by formation of inactive dinitrosyl iron complexes (DNIC). The scavenging of iron ions in turn prevents the oxidative modification of the outer mitochondrial membrane and the release of cytochrome c during reoxygenation. This action of nitrite protects mitochondrial function. The formation of DNIC with nitrite-derived NO could also be confirmed in an ischemia–reperfusion model in liver tissue. Our data suggest that the formation of DNIC is a key mechanism of nitrite-mediated cytoprotection. 相似文献
9.
10.
M. Tyler Caudle Charles D. Caldwell Alvin L. Crumbliss 《Inorganica chimica acta》1995,240(1-2):519-525
A series of dihydroxamic acid ligands of the formula [RN(OH)C(O)]2(CH2)n, (n = 2, 4, 6, 7, 8; R = CH3, H) has been studied in 2.0 M aqueous sodium perchlorate at 25.0 °C. These ligands may be considered as synthetic analogs to the siderophore rhodotorulic acid. Acid dissociation constants (pKa) have been determined for the ligands and for N-methylacetohydroxamic acid (NMHA). The pKa1 and pKa2 values are: n = 2, R = CH3 (8.72, 9.37); N = 4, R = CH3 (8.79, 9.37); N = 6, R = CH3; N = 7, R = CH3 (8.95, 9.47); N = 8, R = CH3 (8.93, 9.45); N = 8, R = H (9.05, 9.58). Equilibrium constants for the hydrolysis of coordinated water (log K) have been estimated for the 1:1 feeric complexes of the ligands n = 2, 4, 8; R = CH3. The N = 8 ligand forms a monomeric complex with Fe(III) while the n = 2 and 4 ligands form dimeric complexes. For hydrolysis of the n = 8 monomeric complex, log K1 = −6.36 and log K2 = −9.84. Analysis of the spectrophotometric data for the dimeric complexes indicates deprotonation of all four coordinated waters. The successive hydrolysis constants, log K1–4, for the dimeric complexes are as follows: n = 2 (−6.37, −5.77, −10.73, −11.8); n = 4 (−5.54, −5.07, −11.57, −10.17). The log K2 values for the dimers are unexpectedly high, higher in fact than log K1, inconsistent with the formation of simple ternary hydroxo complexes. A scheme is proposed for the hydrolysis of the ferric dihydroxamate dimers, which includes the possible formation of μ-hydroxo and μ-oxo bridges. 相似文献
11.
12-Tungstophosphoric acid (PW) supported on different metal oxides (SiO2, γ-Al2O3, KSF, K10) and activated carbon were prepared by impregnation method and their catalytic performances were evaluated in three component condensation of benzaldehyde, ethyl acetoacetate and ammonium acetate to afford corresponding 1,4-dihydropyridine. A high catalytic activity was found over silica supported PW. Effect of PW loading, catalyst loading and solvent was studied to introduce the best reaction condition. Based on the above experimental finding, catalytic performances was optimized with a loading of 40% PW onto SiO2 (0.2 g) under solvent-free condition. The characterization data derived from FT-IR, XRD, and TGA-DSC techniques reveal that the PW on silica support exists in Keggin structure. In addition, acidity measurements were performed by potentiometric titration with n-butylamine. The activity of the catalysts is strongly dependent on their acidic characteristic which, in turn, depended on PW loading. Finally, a series of 4-aryl, N-alkyl, and N-aryl substituted 1,4-dihydropyridines have been synthesized in high to excellent yield in short reaction times. PW/SiO2 was found to be reusable and a considerable catalytic activity still could be achieved after fourth run. 相似文献
12.
J.-L. Primus Marelle G. Boersma Dominique Mandon Sjef Boeren Cees Veeger R. Weiss Ivonne M. C. M. Rietjens 《Journal of biological inorganic chemistry》1999,4(3):274-283
This study describes the catalytic properties of manganese microperoxidase 8 [Mn(III)MP8] compared to iron microperoxidase
8 [Fe(III)MP8]. The mini-enzymes were tested for pH-dependent activity and operational stability in peroxidase-type conversions,
using 2-methoxyphenol and 3,3′-dimethoxybenzidine, and in a cytochrome P450-like oxygen transfer reaction converting aniline
to para-aminophenol. For the peroxidase type of conversions the Fe to Mn replacement resulted in a less than 10-fold decrease in
the activity at optimal pH, whereas the aniline para-hydroxylation is reduced at least 30-fold. In addition it was observed that the peroxidase type of conversions are all fully
blocked by ascorbate and that aniline para-hydroxylation by Fe(III)MP8 is increased by ascorbate whereas aniline para-hydroxylation by Mn(III)MP8 is inhibited by ascorbate. Altogether these results indicate that different types of reactive
metal oxygen intermediates are involved in the various conversions. Compound I/II, scavenged by ascorbate, may be the reactive
species responsible for the peroxidase reactions, the polymerization of aniline and (part of) the oxygen transfer to aniline
in the absence of ascorbate. The para-hydroxylation of aniline by Fe(III)MP8, in the presence of ascorbate, must be mediated by another reactive iron-oxo species
which could be the electrophilic metal(III) hydroperoxide anion of microperoxidase 8 [M(III)OOH MP8]. The lower oxidative
potential of Mn, compared to Fe, may affect the reactivity of both compound I/II and the metal(III) hydroperoxide anion intermediate,
explaining the differential effect of the Fe to Mn substitution on the pH-dependent behavior, the rate of catalysis and the
operational stability of MP8.
Received: 29 September 1998 / Accepted: 16 February 1999 相似文献
13.
运用动力学方法研究了微波对青霉素酰化酶(pK1和pK2分别为5.69-6.06和11.56)催化反应性能的影响。结果显示:使用微波解冻档对青霉素酰化酶进行一定时间的预处理后,能够加速酶的水解反应。酶液的最适处理时间为15 s,微波处理后,酶的最适温度为从原来的37℃上升到40℃,操作稳定性基本不变。对最适微波条件处理后的青霉素酰化酶pH值依赖性催化反应进行研究,从logVm和log(Vm/Km)与pH值关系曲线计算得到该酶的pK1和pK2分别为5.66-6.55和11.05。 相似文献
14.
An electron-rich iron(III) porphyrin complex (meso-tetramesitylporphinato)iron(III) chloride [Fe(TMP)Cl], was found to catalyze the epoxidation of olefins by aqueous 30% H2O2 when the reaction was carried out in the presence of 5-chloro-1-methylimidazole (5-Cl-1-MeIm) in aprotic solvent. Epoxides were the predominant products with trace amounts of allylic oxidation products, indicating that Fenton-type oxidation reactions were not involved in the olefin epoxidation reactions. cis-Stilbene was stereospecifically oxidized to cis-stilbene oxide without giving isomerized trans-stilbene oxide product, demonstrating that neither hydroperoxy radical (HOO·) nor oxoiron(IV) porphyrin [(TMP)FeIV=O] was responsible for the olefin epoxidations. We also found that the reactivities of other iron(III) porphyrin complexes such as (meso-tetrakis(2,6-dichlorophenyl)porphinato)iron(III) chloride [Fe(TDCPP)Cl], (meso-tetrakis(2,6-difluorophenyl)porphinato)iron(III) chloride [Fe(TDFPP)Cl], and (meso-tetrakis(pentafluorophenyl)porphinato)iron(III) chloride [Fe(TPFPP)Cl] were significantly affected by the presence of the imidazole in the epoxidation of olefins by H2O2. These iron porphyrin complexes did not yield cyclohexene oxide in the epoxidation of cyclohexene by H2O2 in the absence of 5-Cl-1-MeIm in aprotic solvent; however, addition of 5-Cl-1-MeIm to the reaction solutions gave high yields of cyclohexene oxide with the formation of trace amounts of allylic oxidation products. We proposed, on the basis of the results of mechanistic studies, that the role of the imidazole is to decelerate the O–O bond cleavage of an iron(III) hydroperoxide porphyrin (or H2O2–iron(III) porphyrin adduct) and that the intermediate transfers its oxygen to olefins prior to the O–O bond cleavage. 相似文献
15.
The kinetics and mechanisms of the complex formation and antioxidant behaviour of the polyphenols EGCg and ECG with iron(III) 总被引:1,自引:0,他引:1
(-)-Epigallocatechin-gallate ((-)-EGCg) and (-)-epicatechin-gallate ((-)-ECG) are important antioxidants which are found in green tea. The kinetics and mechanisms of the reactions of a pseudo-first order excess of iron(III) with EGCg and ECG have been investigated in aqueous solution at 25 degrees C and an ionic strength of 0.5M NaClO(4). Mechanisms have been proposed which account satisfactorily for the kinetic data. These are consistent with a mechanism in which the 2:1 metal:ligand complex initially formed on reaction of iron(III) with the ligand subsequently decomposes in an electron transfer step. Complex formation takes place at two separate binding sites via coupled reactions. Rate constants of 4.28(+/-0.06) x 10(6) M(-2) s(-1) and 2.83(+/-0.04) x 10(6) M(-2) s(-1) have been evaluated for the reaction of monohydroxy Fe(OH)2+ species with EGCg and ECG, respectively while rate constants for of 2.94(+/-0.4) x 10(4) M(-2) s(-1) and 2.41(+/-0.25) x 10(4) M(-2) s(-1) have been evaluated for the reaction of Fe3+ species with EGCg and ECG, respectively. The iron(III) assisted decomposition of the initial iron(III) complex formed was also investigated and the rate constants evaluated. Both the complex formation and subsequent electron transfer reactions of iron(III) with EGCg and ECG were monitored using UV-visible spectrophotometry. All of the suggested mechanisms and calculated rate constants are supported by calculations carried out using global analysis of time dependant spectra. The results obtained show that one molecule of either EGCg or EGC is capable of reducing up to four iron(III) species, a fact which is consistent with the powerful antioxidant properties of the ligands. 相似文献
16.
Topham CM Gul S Resmini M Sonkaria S Gallacher G Brocklehurst K 《Journal of theoretical biology》2000,204(2):239-256
The theoretical foundation has been laid for the investigation of catalytic systems using first-order kinetics and for a general kinetic method of investigation of the active site content, E(a), of enzymes, catalytic antibodies, and other enzyme-like catalysts. The method involves a combination of steady-state and single-turnover kinetics to provide Vmax and Km and k(lim)(obs) and K(app)(m), respectively. The validity of the method is shown to remain valid for two extensions of the simple two-step enzyme catalysis model (a) when the catalyst preparation contains molecules (Eb) that bind substrate but fail to catalyse product formation and (b) when the catalyst itself binds substrate non-productively as well as productively. The former is a particularly serious complication for polyclonal catalytic antibodies and the latter a potential complication for all catalysts. For the simple model and for (b) Vmax/k(lim)(obs) provides the value of [Ea]T and for (a) its upper limit. This can be refined by consideration of the relative values of Km and the equilibrium dissociation constant of EbS. For the polyclonal catalytic antibody preparation investigated, the fact that K(app/m) > Km demonstrates for the first time the presence of a substrate-binding but non-catalytic component in a polyclonal preparation. First-order behaviour in catalytic systems occurs not only with a large excess of catalyst over substrate but also with lower catalyst/substrate ratios, including the equimolar condition, when K(app)(m) > [S]0, a phenomenon that is not widely appreciated. 相似文献
17.
Joanna Ziomek Ewa Zgrabczyńska Adrianna Poradzisz 《Der Zoologische Garten (in deutscher Sprache / in German)》2009,78(4):221-231
Studies on the behaviour of the common hamster are very rare and fragmentary. From August till the middle of September 2005 we observed behaviour of six individuals of the common hamster (one female and five juveniles: three males and two females) and from the second part of September till October 2005 we observed behaviour of two juvenile males after they were separated from the group. The “Focal animal sampling” was used as an observation method, and the total time of observation amounted to 75 hours. During our observation 7707 bouts of behaviour were recorded. Both social and non-social behaviour were categorised. The number of the non-social behaviour prevailed significantly over the number of the social behaviour (n=496; 6.4%). The most frequent observed non-social behaviour was: head rearing (n=2019; 28%). Among interindividual interactions “escape” (45.4%; n=225) and “vocalisation” (15.7%; n=78) were noticed most frequently. Play-fighting, direct identification, following and hugging were the only aspects of the social behaviour characteristic of the young.The behaviour repertoire of the common hamster seems to be similar to the behaviour of the golden hamster (Mesocricetus auratus). 相似文献
18.
Yan Z. Voloshin Oleg A. Varzatskii Andrey Yu. Lebedev Mikhail E. Gurskii Zoya A. Starikova 《Inorganica chimica acta》2007,360(5):1543-1554
The iron(II) clathrochelates with apical adamantyl substituents were synthesized by the direct template reaction on a metal ion matrix. The nucleophilic substitutions of reactive hexachloride precursors with adamantylthiolate anion afforded hexa- and octaadamantyl cage iron(II) complexes. Clathrochelates obtained have been characterized using elemental analysis, MALDI-TOF mass, IR, UV-Vis, 57Fe Mössbauer and 1H, 13C NMR spectroscopies, and X-ray crystallography. Configurations intermediate between trigonal prismatic and trigonal antiprismatic have been deduced for the low-spin iron(II) ion coordination polyhedra of all clathrochelates obtained using 57Fe Mössbauer parameters and confirmed by X-ray crystallography data. Two apical and up to six ribbed adamantyl substituents allow one to change the physical properties of clathrochelates synthesized in wide range. In particular, these substituents form second (hydrophobic) shell that opens up the possibility to membrane and cellular transport of the cage complexes. 相似文献
19.
Wonwoo Nam Ha J. Lee So-Young Oh Cheal Kim Ho G. Jang 《Journal of inorganic biochemistry》2000,80(3-4)
An electron-rich iron(III) porphyrin complex (meso-tetramesitylporphinato)iron(III) chloride [Fe(TMP)Cl], was found to catalyze the epoxidation of olefins by aqueous 30% H2O2 when the reaction was carried out in the presence of 5-chloro-1-methylimidazole (5-Cl-1-MeIm) in aprotic solvent. Epoxides were the predominant products with trace amounts of allylic oxidation products, indicating that Fenton-type oxidation reactions were not involved in the olefin epoxidation reactions. cis-Stilbene was stereospecifically oxidized to cis-stilbene oxide without giving isomerized trans-stilbene oxide product, demonstrating that neither hydroperoxy radical (HOO·) nor oxoiron(IV) porphyrin [(TMP)FeIV=O] was responsible for the olefin epoxidations. We also found that the reactivities of other iron(III) porphyrin complexes such as (meso-tetrakis(2,6-dichlorophenyl)porphinato)iron(III) chloride [Fe(TDCPP)Cl], (meso-tetrakis(2,6-difluorophenyl)porphinato)iron(III) chloride [Fe(TDFPP)Cl], and (meso-tetrakis(pentafluorophenyl)porphinato)iron(III) chloride [Fe(TPFPP)Cl] were significantly affected by the presence of the imidazole in the epoxidation of olefins by H2O2. These iron porphyrin complexes did not yield cyclohexene oxide in the epoxidation of cyclohexene by H2O2 in the absence of 5-Cl-1-MeIm in aprotic solvent; however, addition of 5-Cl-1-MeIm to the reaction solutions gave high yields of cyclohexene oxide with the formation of trace amounts of allylic oxidation products. We proposed, on the basis of the results of mechanistic studies, that the role of the imidazole is to decelerate the O–O bond cleavage of an iron(III) hydroperoxide porphyrin (or H2O2–iron(III) porphyrin adduct) and that the intermediate transfers its oxygen to olefins prior to the O–O bond cleavage. 相似文献
20.
Two low-spin Fe(III) dicyano-dicarboxamido complexes have been prepared from N,N′-bis(8-quinolyl)malonamide derivatives. Crystal structures show that the four nitrogen donors available to complex the metal are arranged in the equatorial plane with the two cyanides trans to each other in the axial positions when the malonyl moiety is disubstituted. In contrast, the unsubstituted malonyl results in only three nitrogens in the equatorial plane with the fourth in an apical position and the two cyanides occupying cis sites, one equatorial and the other axial. NMR analyses show that the solid state structure of both complexes is retained in solution. Both types of configurational complexes catalyze cyclic olefin oxidations with H2O2 but only the cis-dicyano complex catalyzes stilbene oxidation with formation of epoxides, diols and benzaldehyde. 相似文献