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1.
Luigi Mons Scolaro Antonino Mazzaglia Andrea Romeo Maria Rosaria Plutino Mariangela Castriciano Raffaello Romeo 《Inorganica chimica acta》2002,330(1):189-196
The reaction of the monoalkyl complex trans-[Pt(DMSO)2Cl(CH3)] with a large variety of heterocyclic nitrogen bases L, in chloroform solution, leads to the formation of uncharged complexes of the type [Pt(DMSO)(L)Cl(CH3)], containing four different groups coordinated to the metal center. Only two out of the three different possible isomers were detected in solution. These two trans(C,N) and cis(C,N) species can be unambiguously identified through 1H NMR spectroscopy. For the trans(C,N) isomers, average values of 2JPtH=75±4 Hz and 3JPtH=36±4 Hz have been observed for the coordinated methyl and DMSO ligands, respectively. In the case of the cis(C,N) isomers, these values increase to 2JPtH=83±2 Hz, and decrease to 3JPtH=26±3 Hz due to the mutual exchange of ligands in trans position to CH3 and DMSO. In the case of bulky asymmetric ligands, such as quinoline, 2-quinolinecarboxaldehyde, 2-methylquinoline, 5-aminoquinoline, 2-phenylpyridine and 2-chloropyridine, slow rotation of the hindered group around the Pt---N bond makes the coordinated DMSO ligand prochiral. NMR experiments have shown that the first reaction product is the trans(C,N) isomer as a consequence of the very fast removal of one DMSO ligand by the nitrogen bases from the starting complex trans-[Pt(DMSO)2Cl(CH3)]. This trans kinetic product undergoes a geometrical conversion into the more stable cis(C,N) isomer through the intermediacy of fast exchanging aqua-species. The rate of isomerization and the relative stability of the two isomers depends essentially on the rate of aquation and on the steric congestion imposed by the new L ligand on the metal. 相似文献
2.
[10D-3H; 3-14C]- and [10L-3H; 3-14C]arachidonic acids were incubated with human polymorphonuclear leukocytes and with human platelets. Leukotriene B4 and 5(S),12(S)-dihydroxy-6trans,8cis,10trans,14-cis-eicosatetraenoic acid (5,12-DHETE) were isolated and the 3H/14C ratios determined. It could be concluded that the 10D (pro-R)-hydrogen is eliminated in the conversion of 5(S)-hydroperoxy-6trans,8cis,11cis,14cis-eicosatetraenoic acid into leukotriene A4 whereas in the conversion of arachidonic acid into 5,12-DHETE the 10L (pro-S)-hydrogen is lost. Incubation of the doubly labeled arachidonic acids with human platelets confirmed and extended previous data on the stereochemistry of the hydrogen removal from C-10 during the conversion into 12(S)-hydroperoxy-5cis,8cis,10trans,14cis-eicosatetraenoic acid, i.e., the 10L (pro-S)-hydrogen is eliminated and the 10D (pro-R)-hydrogen retained. 相似文献
3.
Chloroperoxidase-catalysed oxidation of alcohols to aldehydes 总被引:1,自引:0,他引:1
Chloroperoxidase (CPO) catalyses the oxidation of primary alcohols (hexan-1-ol, hexen-1-ols, epoxyhexan-1-ols and 3-phenylglycidol) selectively to the aldehyde in biphasic systems of hexane or ethyl acetate and a buffer (pH 5.0). The cis to trans isomerization in the case of cis-2-hexenal can be avoided by working at low water contents or in organic solvents saturated with water. In the case of epoxyalcohols, oxidation to the aldehyde proceeds enantioselectively. Hydrogen peroxide and tert-butyl hydroperoxide have been used as an oxidant. 相似文献
4.
The dinuclear Pt---Si complex {(Ph3P)Pt{μ-η2-H---SiH(IMP)]}2 (trans-1a–cis-1b=3:1; IMP=2-isopropyl-6-methylphenyl) reacted with basic phosphines such as 1,2-bis(diphenylphosphino)ethane (dppe) and dimethylphenylphosphine (PMe2Ph) to afford different dinuclear Pt---Si complexes with loss of H2, {(P)2Pt[μ-SiH(IMP)]}2 [P=dppe, trans-2a (major), cis-2b (trace); PMe2Ph, 3 (trans only)]. Complexes 2 and 3 were characterized by multinuclear NMR spectroscopy and X-ray crystallography (2a). In contrast, the reaction of 1a,b with the sterically demanding tricyclohexylphosphine (PCy3) afforded {(Cy3P)Pt{μ-η2-H---SiH(IMP)]}2 (trans-4a–cis-4b 2:1) analogous to 1a,b where the central Pt2Si2(μ-H)2 core remains intact but the PPh3 ligands have been replaced by PCy3. Complexes 4a and 4b was characterized by multinuclear NMR and IR spectroscopies. 相似文献
5.
Roseli Maria De Conti Andr L. M. Porto J. Augusto R. Rodrigues Paulo J. S. Moran Gilson P. Manfio Anita J. Marsaioli 《Journal of Molecular Catalysis .B, Enzymatic》2001,11(4-6):233-236
A Brazilian strain of the bacteria Serratia rubidaea CCT 5742 quantitatively reduced 4-tert-butylcyclohexanone and 4-methylcyclohexanone to the less thermodynamically stable diastereoisomeric alcohols cis-4-tert-butylcyclohexanol and cis-4-methylcyclohexanol with a diastereoisomeric excesses (de) of 96% and 44%, respectively. 2-Methylcyclohexanone was also totally reduced to the corresponding alcohols affording the trans-(+)-(1S, 2S)-2-methylcyclohexanol with 78% of de and an enantiomeric excess (ee) of 80%. The cis-(+)-(1S, 2R)-2-methylcyclohexanol was obtained in 98% ee. 相似文献
6.
Mozhgan Khorasani-Motlagh Nasser Safari Craig B. Pamplin Brian O. Patrick Brian R. James 《Inorganica chimica acta》2001,320(1-2):184-189
From a mixture of cis- and trans-Ru(SH)2(dppm)2 (4), formed from reaction of H2S with trans-Ru(H)Cl(dppm)2 (2), a crystal of cis-4 has been isolated and its structure determined by X-ray analysis. The mercapto protons are located within the centrosymmetric structure, although the S-atoms are partially disordered (S–H1.06 Å). The thiolate complexes, trans-Ru(H)SR(dppm)2 (R=Ph, 5a; C6F5, 5b), have been isolated from reaction of trans-2 with 1 equiv. of RSH. trans-Ru(H)SH(dppm)2 (3) has been isolated from reaction of H2S with a mixture of cis- and trans-Ru(H)2(dppm)2 (1). An improved synthetic route for 1 is presented. 相似文献
7.
Patrick W. Blosser Mario Calligaris David G. Schimpff Andrew Wojcicki 《Inorganica chimica acta》2001,320(1-2):110-116
Reactions of [(PPh3)2Pt(η3-CH2CCPh)]OTf with each of PMe3, CO and Br− result in the addition of these species to the metal and a change in hapticity of the η3-CH2CCPh to η1-CH2CCPh or η1-C(Ph)=C=CH2. Thus, PMe3 affords [(PMe3)3Pt(η1-C(Ph)=C=CH2)]+, CO gives both [trans-(PPh3)2Pt(CO)(η1-CH2CCPh)]+ and [trans-(PPh3)2Pt(CO)(η1-C(Ph)=C=CH2)]+, and LiBr yields cis-(PPh3)2PtBr(η1-CH2CCPh), which undergoes isomerization to trans-(PPh3)2PtBr(η1-CH2CCPh). Substitution reactions of cis- and trans-(PPh3)2PtBr(η1-CH2CCPh) each lead to tautomerization of η1-CH2CCPh to η1-C(Ph)=C=CH2, with trans-(PPh3)2PtBr(η1-CH2CCPh) affording [(PMe3)3Pt(η1-C(Ph)=C=CH2)]+ at ambient temperature and the slower reacting cis isomer giving [trans-(PPh3)(PMe3)2Pt(η1-C(Ph)=C=CH2)]+ at 54 °C . All new complexes were characterized by a combination of elemental analysis, FAB mas spectrometry and IR and NMR (1H, 13C{1H} and 31P{1H}) spectroscopy. The structure of [(PMe3)3Pt(η1-C(Ph)=C=CH2)]BPh4·0.5MeOH was determined by single-crystal X-ray diffraction analysis. 相似文献
8.
Anna-Lena Gustavsson Mattias C. Larsson Bill S. Hansson Tommy Liljefors 《Bioorganic & medicinal chemistry》1997,5(12):2173-2183
The enantiomers of cis- and trans-3-(4-propyl-cyclopent-2-enyl) propyl acetate, which are conformationally constrained analogues of (Z)-5-decenyl acetate (1), a sex pheromone component of the turnip moth, Agrotis segetum, have been synthesized and tested using the electrophysiological single-sensillum technique. The analogues mimic a cisoid and transoid conformation of 1, respectively. In addition, the enantiomers of each of the cis- and trans-isomers are conformationally constrained analogues of enantiomeric cisoid and transoid conformations of 1. Thus, the compounds prepared and tested are well suited to investigate the nature of the bioactive conformation of the natural pheromone component 1 and the chiral sense of its interaction with the receptor. Electrophysiological single-sensillum recordings show that the activity of the most active cis-isomer, which has a (1S,4R)-configuration, is more than two orders of magnitude higher than that of the most active trans-isomer. Furthermore, the (1S,4R)-isomer is at least 100 times more active than its enantiomer. These results strongly support a previously proposed cisoid bioactive conformation of 1. Furthermore, the (1S,4R)-configuration of most active stereoisomer identifies the chiral sense of the interaction between the natural pheromone component 1 and its receptor. 相似文献
9.
Conjugated linoleic acids: are they beneficial or detrimental to health? 总被引:25,自引:0,他引:25
Conjugated linoleic acids (CLAs) comprise a family of positional and geometric isomers of linoleic acid (18:2n − 6; LA) that are formed by biohydrogenation and oxidation processes in nature. The major dietary sources of these unusual fatty acids are foods derived from ruminant animals, in particular dairy products. The main form of CLA, cis-9, trans-11-18:2, can be produced directly by bacterial hydrogenation in the rumen or by delta-9 desaturation of the co-product vaccenic acid (trans-11-18:1) in most mammalian tissues including man. The second most abundant isomer of CLA is the trans-10, cis-12-18:2 form. Initially identified in grilled beef as a potential anti-carcinogen a surprising number of health benefits have subsequently been attributed to CLA mixtures and more recently to the main individual isoforms. It is also clear from recent studies that the two main isoforms can have different effects on metabolism and cell functions and can act through different cell signalling pathways. The majority of studies on body compositional effects (i.e. fat loss, lean gain), on cancer and cardiovascular disease attenuation, on insulin sensitivity and diabetes and on immune function have been conducted with a variety of animal models. Observations clearly emphasise that differences exist between mammalian species in their response to CLAs with mice being the most sensitive. Recent studies indicate that some but not all of the effects observed in animals also pertain to human volunteers. Reports of detrimental effects of CLA intake appear to be largely in mice and due mainly to the trans-10, cis-12 isomer. Suggestions of possible deleterious effects in man due to an increase in oxidative lipid products (isoprostanes) with trans-10, cis-12 CLA ingestion require substantiation. Unresponsiveness to antioxidants of these non-enzymatic oxidation products casts some doubt on their physiological relevance. Recent reports, albeit in the minority, that CLAs, particularly the trans-10, cis-12 isomer, can elicit pro-carcinogenic effects in animal models of colon and prostate cancer and can increase prostaglandin production in cells also warrant further investigation and critical evaluation in relation to the many published anti-cancer and anti-prostaglandin effects of CLAs. 相似文献
10.
Gialih Lin Fu-Hwey Lai Bo-I Tsai Chi-Wei Hsieh Hou-Jen Tsai 《Journal of Molecular Catalysis .B, Enzymatic》2006,40(3-4):86-92
The aim of this study is to probe the glycerol backbone conformation of the substrate (or inhibitor) in the active site of Pseudomonas species lipase by the 1,2-cyclopentandiol analogues of the ethylene glycerol carbamate inhibitors. Cyclopentane-carbamates, cis-1,2-di-N-n- butylcarbamyl-cyclopentane (1) and trans-1,2-di-N-n-butylcarbamyl-cyclopentane (2), are the conformationally constrained analogues of 1,2-di-N-n-butylcarbamyl ethane (3). All carbamates are synthesized and characterized as the pseudo-substrate inhibitors of the enzyme. Cis-cyclopentane-di-carbamate (1) is a more potent inhibitor than both ethane-di-carbamate (3) and trans-cyclopentane-di-carbamate (2) probably because the glycerol backbone conformations of cis-cyclopentane-di-carbamate (1) are constrained by the cyclopentane ring and cis-cyclopentane-di-cabamate (1) is a meso compound but trans-cyclopentane-di-carbamate (2) is a racemate. 相似文献
11.
Umberto Belluco Roberta Bertani Rino A. Michelin Mirto Mozzon Franco Benetollo Gabriella Bombieri Robert J. Angelici 《Inorganica chimica acta》1995,240(1-2):567-574
The chloro complexes trans-[Pt(Me)(Cl)(PPh3)2], after treatment with AgBF4, react with 1-alkynes HC---C---R in the presence of NEt3 to afford the corresponding acetylide derivatives trans-[Pt(Me) (C---C---R) (PPh3)2] (R = p-tolyl (1), Ph (2), C(CH3)3 (3)). These complexes, with the exception of the t-butylacetylide complex, react with the chloroalcohols HO(CH2)nCl (n = 2, 3) in the presence of 1 equiv. of HBF4 to afford the alkyl(chloroalkoxy)carbene complexes trans-[Pt(Me) {C[O(CH2)nCl](CH2R) } (PPh3)2][BF4] (R = p-tolyl, N = 2 (4), N = 3 (5); R=Ph, N = 2 (6)). A similar reaction of the bis(acetylide) complex trans-[Pt(C---C---Ph)2(PMe2Ph)2] with 2 equiv. HBF4 and 3-chloro-1-propanol affords trans-[Pt(C---CPh) {C(OCH2CH2CH2Cl)(CH2Ph) } (PMe2Ph)2][BF4] (7). T alkyl(chloroalkoxy)-carbene complex trans-[Pt(Me) {C(OCH2CH2Cl)(CH2Ph) } (PPh3)2][BF4] (8) is formed by reaction of trans-[Pt(Me)(Cl)(PPh3)2], after treatment with AgBF4 in HOCH2CH2Cl, with phenylacetylene in the presence of 1 equiv. of n-BuLi. The reaction of the dimer [Pt(Cl)(μ-Cl)(PMe2Ph)]2 with p-tolylacetylene and 3-chloro-1-propanol yields cis-[PtCl2{C(OCH2CH2CH2Cl)(CH2C6H4-p-Me}(PMe2Ph)] (9). The X-ray molecular structure of (8) has been determined. It crystallizes in the orthorhombic system, space group Pna21, with a = 11.785(2), B = 29.418(4), C = 15.409(3) Å, V = 4889(1) Å3 and Z = 4. The carbene ligand is perpendicular to the Pt(II) coordination plane; the PtC(carbene) bond distance is 2.01(1) Å and the short C(carbene)-O bond distance of 1.30(1) Å suggests extensive electronic delocalization within the Pt---C(carbene)---O moietry. 相似文献
12.
Lodovico Lunazzi Giuseppe Placucci Loris Grossi Antonino Strocchi 《Chemistry and physics of lipids》1982,30(4):347-352
Addition of Yb(fod)3 to methyl oleate (cis) and methyl elaidate (trans) shifts the carboxylic lines of their 13C-NMR spectra to different extents; that of the cis isomer less than that of the trans isomer, as is to be expected.
On the same theoretical ground it can be anticipated that the opposite will occur for C-17: an effect that has been confirmed experimentally. The method is thus proposed as a means of aiding in the assignment of the cis and trans configuration in esters of fatty acids with one double bond. 相似文献
13.
Effect of monensin, fish oil or their combination on in vitro fermentation and conjugated linoleic acid (CLA) production by ruminal bacteria 总被引:2,自引:0,他引:2
An in vitro study was conducted to examine the effect of adding monensin, fish oil, or their combination on rumen fermentation and conjugated linoleic acid (CLA) production by mixed ruminal bacteria when incubated with safflower oil. Concentrate (1 g/100 ml) with safflower oil (0.2 g/100 ml) was added to a mixed solution (600 ml) of strained rumen fluid and buffer (control). Monensin (10 ppm), fish oil (0.02 g/100 ml), or monensin plus fish oil was also added into control mixture. All the culture solutions prepared were incubated anaerobically at 39 °C for 12 h. A higher pH and ammonia concentration were observed from the culture solution containing monensin at 12 h of incubation than those from the control or the culture containing fish oil. Monensin increased (P < 0.007) the C3 content over all the collection times of culture solution while reducing the C4 content at 6 h (P < 0.018) and 12 h (P < 0.001) of incubations. Supplementation of monensin, fish oil or their combination changed the content of C18-fatty acids of ruminal culture. Monensin alone reduced (P < 0.021) the content of cis-9, trans-11 CLA compared to fish oil at all sampling times, but increased (P < 0.041) the trans-10, cis-12 CLA production compared to fish oil addition and the control which were similar at incubation for 12 h. The combination of monensin and fish oil increased the content of cis-9, trans-11 CLA (P < 0.023) and transvaccenic acid (TVA, P < 0.018) significantly compared to the control or monensin alone at incubation for 12 h. 相似文献
14.
Catalyzed by Rhodococcus sp. AJ270 microbial cells under very mild conditions, racemic 2,2-dimethylcyclopropanecarbonitrile (1) and its amide (2), and trans- and cis-2-methylcyclopropanecarboxamides (4) and (7) underwent enantioselective hydrolysis to give the corresponding optically active amides and acids. 相似文献
15.
Alan J. Lough Robert H. Morris Leonarda Ricciuto Thomas Schleis 《Inorganica chimica acta》1998,270(1-2):238-246
The complex [Ru(H2)(H)(PMe2Ph)4]PF6 (1) has been prepared by reaction of [Ru(H)(PMe2Ph)5] FP6 (2) in THF with 1 atm H2 and characterised by variable temperature 31P and 1H NMR. It undergoes four distinct fluxional processes listed in order of decreasing activation energy: (i) exchange of H2 in solution with the dihydrogen ligand above 273 K; (ii) isomerisation of cis and trans isomers of 1 above 230 K; (iii) exchange of H atoms between H2 and hydride in trans-1 above 180 K; (iv) rapid H2/hydride exchange in cis-1 to below 180 K. A single crystal X-ray diffraction study of 1 at 173 K shows that the complex has the cis geometry in the solid state but does not clearly reveal the positions of the hydrogen ligands. Complex 1 starts out as a catalyst of high activity for the selective hydrogenation of 1-alkynes to 1-alkenes (RC≡CH; R=11Bu, Ph) but it is rapidly deactivated, possibly because of formation of the enynyl complex [Ru(η3RC3CHR)(PMe2Ph)4]+. Complex 1 efficiently catalyzes the hydrogenation of internal alkynes (3-hexyne, 2-pentyne) to internal cis-alkenes with little deactivation, although some isomerisation of the alkene produced is observed. These observations are consistent with those of Nkosi, Coville, Albers and Singleton who reported that complex 2 must dissociate one PMe2Ph ligand to produce the species active for alkyne hydrogenation. Complex 2 catalyses these hydrogenations with slower initial rates than complex 1 but deactivates less readily. In contrast to 1, complex 2 does not appear to cause the isomerisation of internal alkenes. 相似文献
16.
Kinetic and activation parameter data for the reactions of cct-Ru(H)2(CO)2(PPh3)2 (1) (cct = cis, cis, trans) in THF with thiols, CO and PPh3 to give cct-RuH(SR)(CO)2(PPh3)2, Ru(CO)3(PPh3)2 and Ru(CO)2(PPh3)2, respectively, reveal a common, rate-determining step, the initial dissociation of H2 from 1; the activated complex probably resembles the corresponding Ru(η2-H2) species. Reaction of Ru(H)2(dppm)2 (2) (as a cis/trans mixture, DPPM = bis(diphenylphosphino)methane) with thiols initially generated cis- and trans- RuH(SR) (dppm)2 with a rate that depends on both the type and concentration of thiol. The higher basicity of the hydride ligands in 2 (versus 1), which is demonstrated by deuterium exchange with CD3OD, gives rise in the thiol reaction to an initial protonation step prior to loss of H2. A species detected in the thiol reaction is possibly [RuH(η2-H2 (dppm)2]2, the anticipated intermediate for this reaction and for the hydrogen exchange with alcohol. A longer reaction of 2 with PhCH2SH gives solely cis-Ru(SCH2Ph)2(dppm)2. 相似文献
17.
(S)-(−)- and (R)-(+)-limonene was transformed to carvone via corresponding cis- and trans-carveol using Solanum aviculare and Dioscorea deltoidea plant cells. Both carveols and carvone formed were racemic in all biotransformations. 相似文献
18.
A. M. Cano J. Cano T. Cuenca P. Gmez-Sal A. Manzanero P. Royo 《Inorganica chimica acta》1998,280(1-2):1
The reaction of TiCl4 with Li2[(SiMe2)2(η5-C5H3)2] in toluene at room temperature afforded a mixture of cis- and trans-[(TiCl3)2{(SiMe2)2(η5-C5H3)2}] in a molar ratio of 1/2 after recrystallization. The complex trans-[(TiCl3)2{(SiMe2)2(η5-C5H3)2}] was hydrolyzed immediately by the addition of water to THF solutions to give trans-[(TiCl2)2(μ-O){(SiMe2)2(η5-C5H3)2}] as a solid insoluble in all organic solvents, whereas hydrolysis of cis-[(TiCl3)2{(SiMe2)2(η5-C5H3)2}] under different conditions led to the dinuclear μ-oxo complex cis-[(TiCl2)2)(μ-O){(SiMe2)2(η5-C5H3)2}] and two oxo complexes of the same stoichiometry [(TiCl)2(μ-O){(SiMe2)2(η5-C5H3)2}]2(μ-O)2 as crystalline solids. Alkylation of cis- and trans-[(TiCl3)2{(SiMe2)2(η5-C5H3)2}] with MgCIMe led respectively to the partially alkylated cis-[(TiMe2Cl)2{(SiMe2)2(η5-C5H3)2}] and the totally alkylated trans-[(TiMe3)2{(SiMe2)2(η5-C5H3)2}] compounds. The crystal and molecular structure of the tetranuclear oxo complex [(TiCl)2(μ-O){(SiMe2)2(η5-C5H3)2}]2(μ-O)2 was determined by X-ray diffraction. 相似文献
19.
Konstantinos D. Demadis Mohammed Bakir Bert G. Klesczewski Darryl S. Williams Peter S. White Thomas J. Meyer 《Inorganica chimica acta》1998,270(1-2):511-526
Rapid reactions occur between [OsVI(tpy)(Cl)2(N)]X (X = PF6−, Cl−, tpy = 2,2′:6′,2″-terpyridine) and aryl or alkyl phosphi nes (PPh3, PPh2Me, PPhMe2, PMe3 and PEt3) in CH2Cl2 or CH3CN to give [OsIV(tpy)(Cl)2(NPPh3)]+ and its analogs. The reaction between trans-[OsVI(tpy)(Cl)2(N)]+ and PPh3 in CH3CN occurs with a 1:1 stoichiometry and a rate law first order in both PPh3 and OsVI with k(CH3CN, 25°C) = 1.36 ± 0.08 × 104 M− s−1. The products are best formulated as paramagnetic d4 phosphoraniminato complexes of OsIV based on a room temperature magnetic moment of 1.8 μB for trans-[OsIV(tpy)(Cl)2(NPPh3)](PF6), contact shifted 1H NMR spectra and UV-Vis and near-IR spectra. In the crystal structures of trans-[OsIV(tpy)(Cl)2( NPPh3)](PF6)·CH3CN (monoclinic, P21/n with a = 13.384(5) Å, b = 15.222(7) Å, c = 17.717(6) Å, β = 103.10(3)°, V = 3516(2) Å3, Z = 4, Rw = 3.40, Rw = 3.50) and cis-[OsIV(tpy)(Cl)2(NPPh2Me)]-(PF6)·CH3CN (monoclinic, P21/c, with a = 10.6348(2) Å, b = 15.146(9) ÅA, c = 20.876(6) Å, β = 97.47(1)°, V = 3334(2) Å3, Z = 4, R = 4.00, Rw = 4.90), the long Os-N(P) bond lengths (2.093(5) and 2.061(6) Å), acute Os-N-P angles (132.4(3) and 132.2(4)°), and absence of a significant structural trans effect rule out significant Os-N multiple bonding. From cyclic voltammetric measurements, chemically reversible OsV/IV and OsIV/III couples occur for trans-[OsIV(tpy)(Cl)2(NPPh3)](PF6) in CH3CN at +0.92 V (OsV/IV) and −0.27 V (OsIV/III) versus SSCE. Chemical or electrochemical reduction of trans-[OsIV(tpy)(Cl)2(NPPh3)](PF6) gives isolable trans-OsIII(tpy)(Cl)2(NPPh3). One-electron oxidation to OsV followed by intermolecular disproportionation and PPh3 group transfer gives [OsVI(tpy)Cl2(N)]+, [OSIII(tpy)(Cl)2(CH3CN)]+ and [Ph3=N=PPh3]+ (PPN+). trans-[OsIV(tpy)(Cl)2(NPPh3)](PF6) undergoes reaction with a second phosphine under reflux to give PPN+ derivatives and OsII(tpy)(Cl)2(CH3CN) in CH3CN or OsII(tpy)(Cl)2(PR3) in CH2Cl2. This demonstrates that the OsVI nitrido complex can undergo a net four-electron change by a combination of atom and group transfers. 相似文献
20.
Lisa Dalla Via Vito Di Noto Maurizio Vidali Fabio Scomazzon Dan Ni Renzo Deana 《Chemico-biological interactions》1998,110(3):315-220
This report presents a comparison of the effects of cis- and trans-diamminedichloroplatinum complexes on in vitro platelet functions. Pretreatment of platelets with cis-platinum (cisplatin) induced a slow, dose-dependent (0.1–0.45 mM), increase in the cytosolic Ca2+ concentration, pleckstrin (47 kDa) phosphorylation and serotonin secretion, as well as a slight shape modification with emission of a few pseudopodia. All these effects were remarkably increased in platelets exposed to trans-platinum (transplatin). The rise in cytosolic Ca2+ concentration and serotonin secretion evoked by stimulation of platelets with thrombin were not significantly influenced by cellular exposure to cis-platinum, whereas they were enhanced and inhibited, respectively, by exposure to trans-platinum. Trans-platinum also inhibited thrombin-promoted platelet aggregation to a greater extent than the cis-isomer. While the viscosity of platelet rich-plasma tended to decrease in the presence of cis-platinum, it tended to increase in the presence of trans-platinum. Taken together, these results indicate that the effects on platelet functions of the efficacious antitumor complex cis-platinum is rather different from that of the inactive complex trans-platinum. Therefore, the in vitro tests of platelet functions employed in this study might provide an index of antitumor drug toxicity and serve as a preliminary indicator of therapeutic efficacy. 相似文献