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1.
WITTENBERG JB 《The Journal of general physiology》1958,41(4):783-804
The composition of the gas mixture secreted into the swim-bladders of several species of fish has been determined in the mass spectrometer. The secreted gas differed greatly from the gas mixture breathed by the fish in the relative proportions of the chemically inert gases, argon, neon, helium, and nitrogen. Relative to nitrogen the proportion of the very soluble argon was increased and the proportions of the much less soluble neon and helium decreased. The composition of the secreted gas approaches the composition of the gas mixture dissolved in the tissue fluid. A theory of inert gas secretion is proposed. It is suggested that oxygen gas is actively secreted and evolved in the form of minute bubbles, that inert gases diffuse into these bubbles, and that the bubbles are passed into the swim-bladder carrying with them inert gases. Coupled to a preferential reabsorption of oxygen from the swim-bladder this mechanism can achieve high tensions of inert gas in the swim-bladder. The accumulation of nearly pure nitrogen in the swim-bladder of goldfish (Carassius auratus) is accomplished by the secretion of an oxygen-rich gas mixture followed by the reabsorption of oxygen. 相似文献
2.
A. A. Chukalovsky T. V. Rakhimova K. S. Klopovsky N. A. Popov Yu. A. Mankelevich O. V. Proshina 《Plasma Physics Reports》2014,40(1):34-51
Available data on the kinetic processes in H2-O2-O2(a 1Δ g ) mixtures are analyzed theoretically, and the ranges in which the rate constants of these processes can vary are determined. The processes of energy transformation in an O2(a 1Δ g )-H2-H-HO2 system in the approximations of the fast and slow (in comparison with the vibrational relaxation time of the HO2 radical) quenching of the electronically excited state are considered. The experiments on the quenching of singlet delta oxygen (SDO) molecules O2(a 1Δ g ) excited in a microwave discharge at a temperature of 300 K and pressure of 6 Torr in a lean hydrogen-oxygen mixture are simulated (by a lean fuel mixture is meant a mixture in which the ratio of the fuel to the oxidizer mass fraction is less than the stoichiometric ratio, which is 2: 1 for a hydrogen-oxygen mixture). It is shown that, over the experimental observation times, the SDO quenching frequency depends on the concentration of molecular hydrogen, the residual odd oxygen fraction in the gas flow, and the ratio between the rate constants of kinetic processes involving HO2 and HO2* radicals. Simulations of the microwave discharge and the transport of excited oxygen along the drift tube make it possible to determine the residual odd oxygen concentration in the gas flow. Recommendations on the choice of the rate constants for the O2(a 1Δ g ) + HO2)A″, v3″ = 0) ? O2 + HO2*(A′, v3′ = 1), HO2*(A′v3′ ≤ 1) + O2(a 1Δ g ) → HO2*(A′,v3′ ≥ 6) + O2, and HO2*(A′,v3′ ≤ 1) + O2(a 1Δ g ) → H + O2 + O2 processes are given. It is shown that, in the case of slow quenching in a H2-O2-O2(a 1Δ g ) mixture at a low temperature, the intensity of hydrogen oxidation is enhanced due to the reaction + HO2*(A′,v3′ ≤ 1) + O2(1Δ) → H + O2 + O2. 相似文献
3.
Carlo dela Se?a Kenneth M. Riedl Sureshbabu Narayanasamy Robert W. Curley Jr. Steven J. Schwartz Earl H. Harrison 《The Journal of biological chemistry》2014,289(19):13661-13666
β-Carotene 15–15′-oxygenase (BCO1) catalyzes the oxidative cleavage of dietary provitamin A carotenoids to retinal (vitamin A aldehyde). Aldehydes readily exchange their carbonyl oxygen with water, making oxygen labeling experiments challenging. BCO1 has been thought to be a monooxygenase, incorporating oxygen from O2 and H2O into its cleavage products. This was based on a study that used conditions that favored oxygen exchange with water. We incubated purified recombinant human BCO1 and β-carotene in either 16O2-H218O or 18O2-H216O medium for 15 min at 37 °C, and the relative amounts of 18O-retinal and 16O-retinal were measured by liquid chromatography-tandem mass spectrometry. At least 79% of the retinal produced by the reaction has the same oxygen isotope as the O2 gas used. Together with the data from 18O-retinal-H216O and 16O-retinal-H218O incubations to account for nonenzymatic oxygen exchange, our results show that BCO1 incorporates only oxygen from O2 into retinal. Thus, BCO1 is a dioxygenase. 相似文献
4.
[4-14C]Cholesterol was incubated with an adrenocortical preparation in the presence of 16O2 and 18O2 devoid of significant 16O18O. Isolated (20R,22R)-20,22-dihydroxycholesterol was converted to a trimethylsilyl derivative and analyzed by gas chromatography - mass spectrometry to determine the isotope distribution of the oxygen atoms at C-20 and C-22. The ions of 289, 291, and 293 (comprising the C8 C-20 to C-27 side-chain and containing, respectively, 16O2, 16O18O, and 18O2) exhibited a binomial distribution indicating that the oxygen atoms of the vicinal glycol were drawn at random from the atomic pool of the oxygen molecules. If both side-chain hydroxyl groups had originated from the atoms of the same oxygen molecule, the ion of 291 would have been absent. 相似文献
5.
The active transport of oxygen and carbon dioxide into the swim-bladder of fish is
discussed. The rete mirabile is a capillary network which is involved in the gas secretion
into the bladder. The rete is regarded as a counter-current multiplier. Lactic acid which
is produced in the gas gland generates in the rete single concentrating effects for oxygen
and carbon dioxide; i.e., for equal partial pressures the concentrations of the gases in
the afferent rete capillaries are higher than those in the efferent ones. The single
concentrating effects were calculated from measurements of sea robin blood (Root, 1931).
The multiplication of these effects within the rete for different rete lengths and
different transport rates was numerically evaluated. The calculated O2 and
CO2 pressures in the bladder are in good agreement with the experimental
results of Scholander and van Dam (1953). The descent velocities at equilibrium between
bladder pressure and hydrostatic pressure are discussed for fishes with different rete
lengths. 相似文献
6.
Nocardia paraffinicum (Rhodococcus rhodochrous), a hydrocarbon-degrading microorganism, was used in a study of propane and isobutane metabolism. The bacterium was able to utilize propane or isobutane as a sole source of carbon, and oxygen was found to be essential for its metabolism. Gas chromatographic analysis showed that n-propanol was the major compound recovered from the metabolism of propane by resting cells, although trace amounts of isopropanol and acetone were detected. When a mixture of propane and isobutane was used, drastic inhibition (72 to 88%) of hydrocarbon utilization by resting cells occurred. The ratio of hydrocarbon to oxygen consumed was found to be approximately 2:1 during the metabolism of propane or isobutane by resting cells when these substrates were provided individually to the organism. Gas chromatographic-mass spectrometric analysis of products formed from 18O2 confirmed that the initial oxidative step in the metabolism of these substrates involved molecular oxygen. The proportion of the alcohol containing 18O was the same as that of 18O2 in the gas mixture. Only a negligible amount of 18O was detected in the alcohol when H218O was incorporated into the system. The observed 2:1 ratio of hydrocarbon to oxygen consumption suggests that the oxygenase in N. paraffinicum, unlike the conventional mono- or dioxygenases, requires two hydrocarbon-binding sites for each of the oxygen-binding sites and is therefore an intermolecular dioxygenase. The newly described oxygenase, which catalyzes the reaction of two molecules of propane with one molecule of oxygen to yield two molecules of a C3 alcohol, is proposed as the initial oxidation step of the hydrocarbon substrate. 相似文献
7.
The Secretion of Oxygen into the Swim-bladder of Fish : II. The simultaneous transport of carbon monoxide and oxygen
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Toadfish, Opsanus tau, L., were maintained in sea water equilibrated with gas mixtures containing a fixed proportion of oxygen and varying proportions of carbon monoxide. The swim-bladder was emptied by puncture, and, after an interval of 24 or 48 hours, the newly secreted gases were withdrawn and analyzed. Both carbon monoxide and oxygen are accumulated in the swim-bladder at tensions greater than ambient. The ratio of concentrations, carbon monoxide (secreted): carbon monoxide (administered) bears a constant relation to the ratio, oxygen (secreted): oxygen (administered). The value of the partition coefficient describing this relation is (α = 5.44). The two gases are considered to compete for a common intracellular carrier mediating their active transport. The suggestion is advanced that the intracellular oxygen carrier is a hemoglobin. Comparison of the proportions of carboxy- and oxyhemoglobin in the blood with the composition of the secreted gas proves that the secreted gases are not evolved directly from combination with blood hemoglobin. The suggestion is advanced that cellular oxygen secretion occurs in the rete mirabile: the rete may build up large oxygen tensions in the gas gland capillaries. It is suggested that the gas gland acts as a valve impeding back diffusion of gases from the swim-bladder. 相似文献
8.
Muhammad Akhtar Michael R. Calder David L. Corina J. Neville Wright 《The Biochemical journal》1982,201(3):569-580
Mechanistic aspects of the biosynthesis of oestrogen have been studied with a microsomal preparation from full-term human placenta. The overall transformation, termed the aromatization process, involves three steps using O2 and NADPH, in which the C-19 methyl group of an androgen is oxidised to formic acid with concomitant production of the aromatic ring of oestrogen: [Formula: see text] To study the mechanism of this process in terms of the involvement of the oxygen atoms, a number of labelled precursors were synthesized. Notable amongst these were 19-hydroxy-4-androstene-3,17-dione (II) and 19-oxo-4-androstene-3,17-dione (IV) in which the C-19 was labelled with 2H in addition to 18O. In order to follow the fate of the labelled atoms at C-19 of (II) and (IV) during the aromatization, the formic acid released from C-19 was benzylated and analysed by mass spectrometry. Experimental procedures were devised to minimize the exchange of oxygen atoms in substrates and product with oxygens of the medium. In the conversion of the 19-[18O] compounds of types (II) and (IV) into 3-hydroxy-1,3,5-(10)-oestratriene-17-one (V, oestrone), it was found that the formic acid from C-19 retained the original substrate oxygen. When the equivalent 16O substrates were aromatized under 18O2, the formic acid from both substrates contained one atom of 18O. It is argued that in the conversion of the 19-hydroxy compound (II) into the 19-oxo compound (IV), the C-19 oxygen of the former remains intact and that one atom of oxygen from O2 is incorporated into formic acid during the conversion of the 19-oxo compound (IV) into oestrogen. This conclusion was further substantiated by demonstrating that in the aromatization of 4-androstene-3,17-dione (I), both the oxygen atoms in the formic acid originated from molecular oxygen. 10β-Hydroxy-4-oestrene-3,17-dione formate, a possible intermediate in the aromatization, was synthesized and shown not to be converted into oestrogen. In the light of the cumulative evidence available to date, stereochemical aspects of the conversion of the 19-hydroxy compound (II) into the 19-oxo compound (IV), and mechanistic features of the C-10–C-19 bond cleavage step during the conversion of the 19-oxo compound (IV) into oestrogen are discussed. 相似文献
9.
Henry W.-S. Chan Gordon Levett Jennifer A. Matthew 《Chemistry and physics of lipids》1979,24(3):245-256
Linoleate hydroperoxides undergo rearrangement leading to their isomerisation in which the OOH group is relocated or the stereochemistry of a double bond changed, or both. The reaction was studied mainly with pure isomers of methyl hydroperoxylinoleates since conditions could be found in which rearrangement occurred with little accompanying decomposition. The rearrangement was found to be non-stereoselective and took place by a free-radical chain mechanism. Using 18O-labelled hydroperoxide on 18O2, it was shown that the oxygen atoms of the OOH group of the hydroperoxides exchanged with surrounding molecular oxygen during the rearrangement. A mechanism for the rearrangement is proposed. 相似文献
10.
The 18O-enrichment of CO2 produced in the light or during the post-illumination burst was measured by mass spectrometry when a photoautotrophic cell suspension of Euphorbia characias L. was placed in photorespiratory conditions in the presence of molecular 18O2. The only 18O-labeled species produced was C18O16O; no C18O18O could be detected. Production of C18O16O ceased after addition of two inhibitors of the photosynthetic carbon-oxidation cycle, aminooxyacetate or aminoacetonitrile, and was inhibited by high levels of CO2. The average enrichment during the post-illumination burst was estimated to be 46 ± 15% of the enrichment of the O2 present during the preceding light period. Addition of exogenous carbonic anhydrase, by catalyzing the exchange between CO2 and H2O, drastically diminished the 18O-enrichment of the produced CO2. The very low carbonio-anhydrase level of the photoautotrophic cell suspension probably explains why the 18O labeling of photorespiratory CO2 could be observed for the first time. These data allow the establishment of a direct link between O2 consumption and CO2 production in the light, and the conclusion that CO2 produced in the light results, at least partially, from the mitochondrial decarboxylation of the glycine pool synthesized through the photosynthetic carbon-oxidation cycle. Analysis of the C18O16O and CO2 kinetics provides a direct and reliable way to assess in vivo the real contribution of photorespiratory metabolism to CO2 production in the light. 相似文献
11.
Incorporation of 18O into CO2 was measured under various buffer conditions when the bioluminescent oxidation of Cypridina luciferin, catalyzed by luciferase, was carried out either in H216O medium with 18O2 gas, or in H218O medium with 16O2 gas. The results indicate that (1) the exchange of oxygen between CO2 and solvent H2O is significantly influenced by the kind of buffer as well as by pH, (2) the exchange of oxygen between solvent H2O and CO2 produced from luciferin in a neutral buffer can be reasonably well estimated from the exchange that takes place when the same amount of CO2 gas is introduced into the same buffer by the presently employed method, and (3) in the Cypridina bioluminescent reaction, one of two oxygens of O2 is quantitatively incorporated into the product CO2 prior to the exchange of oxygen between CO2 and solvent H2O. 相似文献
12.
Oxygen fixation into hydroxyproline in etiolated maize seedlings : verification by tandem mass spectrometry
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Etiolated maize (Zea mays L.) seedlings were grown in the dark for 5 days in an atmosphere enriched with 10.0 atom% 18O2. Hydroxyproline was isolated from root and shoot tissues, purified, and methylated. It was not possible to determine 18O incorporation into hydroxyproline by conventional mass spectrometry because the final product was not sufficiently pure. The final product was analyzed successfully by tandem mass spectrometry. The 18O content of the hydroxyl oxygen atom was 10 ± 0.7 atom%. This result demonstrates that the hydroxyl oxygen atom in hydroxyproline was derived exclusively from molecular oxygen. 相似文献
13.
Role of oxygenases in pisatin biosynthesis and in the fungal degradation of maackiain 总被引:3,自引:1,他引:2
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Some isolates of the plant pathogen Nectria haematococca detoxify the isoflavonoid phytoalexin (−)maackiain by hydroxylation at carbon 6a. Precursor feeding studies strongly suggest that the penultimate step in (+)pisatin biosynthesis by Pisum sativum is 6a-hydroxylation of (+)maackiain. We have used 18O labeling to test the involvement of oxygenases in these two reactions. When fungal metabolism of maackiain took place under 18O2, the product was labeled with 99% efficiency; no label was incorporated by metabolism in H218O. Pisatin synthesized by pea pods in the presence of 18O2 or H218O was a mixture of molecules containing up to three labeled oxygen atoms. Primary mass spectra of such mixtures were complex but were greatly simplified by tandem MS. This analysis indicated that the 6a oxygen of pisatin was derived from H2O and not from O2. Labeling patterns for the other five oxygen atoms were consistent with the proposed pathway for biosynthesis of pisatin and related isoflavonoids. We conclude that the fungal hydroxylation of maackiain is catalyzed by an oxygenase, but the biosynthetic route to the 6a hydroxyl of pisatin is unknown. 相似文献
14.
Although considerable variation has been documented in tree‐ring cellulose oxygen isotope ratios (δ18Ocell) among co‐occurring species, the underlying causes are unknown. Here, we used a combination of field measurements and modelling to investigate the mechanisms behind variations in late‐wood δ18Ocell (δ18Olc) among three co‐occurring species (chestnut oak, black oak and pitch pine) in a temperate forest. For two growing seasons, we quantified among‐species variation in δ18Olc, as well as several variables that could potentially cause the δ18Olc variation. Data analysis based on the δ18Ocell model rules out leaf water enrichment (Δ18Olw) and tree‐ring formation period (Δt), but highlights source water δ18O (δ18Osw) as an important driver for the measured difference in δ18Olc between black and chestnut oak. However, the enriched δ18Olc in pitch pine relative to the oaks could not be sufficiently explained by consideration of the above three variables only, but rather, we show that differences in the proportion of oxygen exchange during cellulose synthesis (pex) is most likely a key mechanism. Our demonstration of the relevance of some species‐specific features (or lack thereof) to δ18Ocell has important implications for isotope based ecophysiological/paleoclimate studies. 相似文献
15.
Stephen R. Parker Marissa N. Darvis Simon R. Poulson Christopher H. Gammons Jack A. Stanford 《Biogeochemistry》2014,117(2-3):539-552
Recent studies have documented the occurrence of dissolved molecular oxygen (DO) in shallow groundwater that is isotopically lighter than can be explained by atmospheric gas exchange or by biogeochemical reactions that consume 16O16O faster than 16O18O. In the present study, spatial gradients in the isotopic composition of DO (δ18O-DO) and dissolved inorganic carbon (δ13C-DIC) were measured in three shallow floodplain aquifers: (1) the Nyack aquifer, of the Middle Fork of the Flathead River in northwest Montana; (2) the Silver Bow Creek floodplain in southwest Montana; and (3) the Umatilla River floodplain in northeast Oregon. The field data show general trends of increasing DIC concentration, decreasing δ13C-DIC, and decreasing DO concentration with increase in groundwater path length. These trends are consistent with consumption of DO and production of DIC by microbial respiration. Although the expected trend of an increase in δ18O-DO with increase in path length was found at an area adjacent to hyporheic recharge at the Nyack floodplain, the majority of groundwater samples collected at Nyack and from the other sites distal to recharge zones had anomalously low δ18O-DO values well below 24.2 ‰, the value corresponding to atmospheric isotopic equilibrium. At the Nyack site, 3H-3He dates were used to estimate groundwater travel time: all groundwater samples with apparent age >1 year had δ18O-DO<24.2 ‰. Previously it has been suggested that diffusion of O2 could be a viable mechanism to explain the existence of isotopically light DO in shallow groundwater. To test this hypothesis, laboratory experiments were conducted to measure the isotopic fractionation of O2 as it diffuses from air across a simulated capillary fringe (made from a floating layer of foam beads) into a stirred, initially anoxic, water column. As expected, 16O16O diffused faster than 16O18O, and the magnitude of isotope fractionation associated with diffusion increased with a decrease in temperature. Fractionation factors (α) calculated from these diffusion experiments were 1.0030 at 15–19 °C and 1.0048 at 8 °C. The combined field and laboratory data suggest that diffusion is an important mechanism to maintain aerobic conditions in shallow groundwater systems, allowing microbial respiration to continue at long distances (km scale) from the source of groundwater recharge. 相似文献
16.
A hallmark of acute lung injury is the accumulation of a protein rich edema which impairs gas exchange and leads to hypoxemia.
The resolution of lung edema is effected by active sodium transport, mostly contributed by apical Na+ channels and the basolateral located Na,K-ATPase. It has been reported that the decrease of Na,K-ATPase function seen during
lung injury is due to its endocytosis from the cell plasma membrane into intracellular pools. In alveolar epithelial cells
exposed to severe hypoxia, we have reported that increased production of mitochondrial reactive oxygen species leads to Na,K-ATPase
endocytosis and degradation. We found that this regulated process follows what is referred as the Phosphorylation–Ubiquitination–Recognition–Endocytosis–Degradation (PURED) pathway. Cells exposed to hypoxia generate reactive oxygen species which activate PKCζ which in turn phosphorylates
the Na,K-ATPase at the Ser18 residue in the N-terminus of the α1-subunit leading the ubiquitination of any of the four lysines
(K16, K17, K19, K20) adjacent to the Ser18 residue. This process promotes the α1-subunit recognition by the μ2 subunit of
the adaptor protein-2 and its endocytosis trough a clathrin dependent mechanism. Finally, the ubiquitinated Na,K-ATPase undergoes
degradation via a lysosome/proteasome dependent mechanism. 相似文献
17.
John C. Deutsch 《Analytical biochemistry》1998,260(2):223
The interaction of water with dehydroascorbic acid was examined by incubating dehydroascorbic acid and ascorbic acid in18O-labeled water for various amounts of time and then oxidizing the products with hydrogen peroxide or reducing the products with mercaptoethanol, with analysis by gas chromatography mass spectrometry. Based on mass changes, dehydroascorbic acid readily exchanged three oxygen atoms with H218O. When mercaptoethanol was used to reduce dehydroascorbic acid (which had been incubated in H218O) to ascorbic acid, the newly formed ascorbic acid also contained three labeled oxygen atoms. However, ascorbic acid incubated in H218O for the same amount of time under identical conditions exchanged only two labeled oxygen atoms. Electron impact mass spectrometry of derivatized ascorbic acid created a decarboxylation product which had only two labeled oxygen atoms, regardless if 3-oxygen-labeled or 2-oxygen-labeled ascorbic acid was the parent compound, isolating the extra oxygen addition to carbon 1. These data suggest that dehydroascorbic acid spontaneously hydrolyzes and dehydrates in aqueous solution and that the hydrolytic-hydroxyl oxygen is accepted by carbon 1. Ascorbic acid, on the other hand, does not show this same tendency to hydrolyze. 相似文献
18.
Chaoji Chen Shaomao Xu Yudi Kuang Wentao Gan Jianwei Song Gegu Chen Glenn Pastel Boyang Liu Yiju Li Hao Huang Liangbing Hu 《Liver Transplantation》2019,9(9)
Trees have an abundant network of channels for the multiphase transport of water, ions, and nutrients. Recent studies have revealed that multiphase transport of ions, oxygen (O2) gas, and electrons also plays a fundamental role in lithium–oxygen (Li–O2) batteries. The similarity in transport behavior of both systems is the inspiration for the development of Li–O2 batteries from natural wood featuring noncompetitive and continuous individual pathways for ions, O2, and electrons. Using a delignification treatment and a subsequent carbon nanotube/Ru nanoparticle coating process, one is able to convert a rigid and electrically insulating wood membrane into a flexible and electrically conductive material. The resulting cell walls are comprised of cellulose nanofibers with abundant nanopores, which are ideal for Li+ ion transport, whereas the unperturbed wood lumina act as a pathway for O2 gas transport. The noncompetitive triple pathway design endows the wood‐based cathode with a low overpotential of 0.85 V at 100 mA g?1, a record‐high areal capacity of 67.2 mAh cm?2, a long cycling life of 220 cycles, and superior electrochemical and mechanical stability. The integration of such excellent electrochemical performance, outstanding mechanical flexibility, and renewable yet cost‐effective starting materials via a nature‐inspired design opens new opportunities for developing portable energy storage devices. 相似文献
19.
I. Emma Huertas Brian Colman George S. Espie Luis M. Lubian 《Journal of phycology》2000,36(2):314-320
The occurrence of an active CO2 transport system and of carbonic anhydrase (CA) has been investigated by mass spectrometry in the marine, unicellular rhodophyte Porphyridium cruentum (S.F. Gray) Naegeli and two marine chlorophytes Nannochloris atomus Butcher and Nannochloris maculata Butcher. Illumination of darkened cells incubated with 100 μM H13CO3? caused a rapid initial drop, followed by a slower decline in the extracellular CO2 concentration. Addition of bovine CA to the medium raised the CO2 concentration by restoring the HCO3?–CO2 equilibrium, indicating that cells were taking up CO2 and were maintaining the CO2 concentration in the medium below its equilibrium value during photosynthesis. Darkening the cell suspensions caused a rapid increase in the extracellular CO2 concentration in all three species, indicating that the cells had accumulated an internal pool of unfixed inorganic carbon. CA activity was detected by monitoring the rate of exchange of 18O from 13C18O2 into water. Exchange of 18O was rapid in darkened cell suspensions, but was not inhibited by 500 μM acetazolamide, a membrane‐impermeable inhibitor of CA, indicating that external CA activity was not present in any of these species. In all three species, the rate of exchange was completely inhibited by 500 μM ethoxyzolamide, a membrane‐permeable CA‐inhibitor, showing that an intracellular CA was present. These results demonstrate that the three species are capable of CO2 uptake by active transport for use as a carbon source for photosynthesis. 相似文献
20.
Sequential conversion of molecular oxygen into peroxo- and hydroperoxo-metal species involved in an effective O2-activation is verified for the TpiPr2Rh system by isolation and characterization of the intermediates. O2-treatment of the Rh(I) precursor, TpiPr2Rh(dppe) (1), in the presence of 3,5-diisopropylpyrazole (H-pziPr2) gives the κ2-peroxometal complex, TpiPr2(H-pziPr2)Rh(κ2-O2) (2), which is subsequently converted to the hydroperoxo complex, TpiPr2(H-pzH2)(pzH2)Rh-OOH (4), upon treatment with pyrazole (H-pzH2). The peroxo species 2 and 4 have been characterized by spectroscopic and crystallographic methods and it is revealed that, in the present N-rich coordination system, the basic peroxo ligands (O2, OOH) form hydrogen-bonding interactions with the proximal N- and NH-functional groups. 相似文献