共查询到20条相似文献,搜索用时 0 毫秒
1.
There is a remarkable redox chemistry of higher oxidation state M(IV)-M(VI) polypyridyl complexes of Ru and Os. They are accessible by proton loss and formation of oxo or nitrido ligands, examples being cis-[RuIV(bpy)2(py)(O)]2+ (RuIV=O2+, bpy=2,2'-bipyridine, and py=pyridine) and trans-[OsVI(tpy)(Cl)2(N)]+ (tpy=2,2':6',2' '-terpyridine). Metal-oxo or metal-nitrido multiple bonding stabilizes the higher oxidation states and greatly influences reactivity. O-atom transfer, hydride transfer, epoxidation, C-H insertion, and proton-coupled electron-transfer mechanisms have been identified in the oxidation of organics by RuIV=O2+. The Ru-O multiple bond inhibits electron transfer and promotes complex mechanisms. Both O atoms can be used for O-atom transfer by trans-[RuVI(tpy)(O)2(S)]2+ (S=CH3CN or H2O). Four-electron, four-proton oxidation of cis,cis-[(bpy)2(H2O)RuIII-O-RuIII(H2O)(bpy)2]4+ occurs to give cis,cis-[(bpy)2(O)RuV-O-RuV(O)(bpy)2]4+ which rapidly evolves O2. Oxidation of NH3 in trans-[OsII(tpy)(Cl)2(NH3)] gives trans-[OsVI(tpy)(Cl)2(N)]+ through a series of one-electron intermediates. It and related nitrido complexes undergo formal N- transfer analogous to O-atom transfer by RuIV=O2+. With secondary amines, the products are the hydrazido complexes, cis- and trans-[OsV(L3)(Cl)2(NNR2)]+ (L3=tpy or tpm and NR2-=morpholide, piperidide, or diethylamide). Reactions with aryl thiols and secondary phosphines give the analogous adducts cis- and trans-[OsIV(tpy)(Cl)2(NS(H)(C6H4Me))]+ and fac-[OsIV(Tp)(Cl)2(NP(H)(Et2))]. In dry CH3CN, all have an extensive multiple oxidation state chemistry based on couples from Os(VI/V) to Os(III/II). In acidic solution, the OsIV adducts are protonated, e.g., trans-[OsIV(tpy)(Cl)2(N(H)N(CH2)4O)]+, and undergo proton-coupled electron transfer to quinone to give OsV, e.g., trans-[OsV(tpy)(Cl)2(NN(CH2)4O)]+ and hydroquinone. These reactions occur with giant H/D kinetic isotope effects of up to 421 based on O-H, N-H, S-H, or P-H bonds. Reaction with azide ion has provided the first example of the terminal N4(2-) ligand in mer-[OsIV(bpy)(Cl)3(NalphaNbetaNgammaNdelta)]-. With CN-, the adduct mer-[OsIV(bpy)(Cl)3(NCN)]- has an extensive, reversible redox chemistry and undergoes NCN(2-) transfer to PPh3 and olefins. Coordination to Os also promotes ligand-based reactivity. The sulfoximido complex trans-[OsIV(tpy)(Cl)2(NS(O)-p-C6H4Me)] undergoes loss of O2 with added acid and O-atom transfer to trans-stilbene and PPh3. There is a reversible two-electron/two-proton, ligand-based acetonitrilo/imino couple in cis-[OsIV(tpy)(NCCH3)(Cl)(p-NSC6H4Me)]+. It undergoes reversible reactions with aldehydes and ketones to give the corresponding alcohols. 相似文献
2.
de Bruin B Boerakker MJ Verhagen JA de Gelder R Smits JM Gal AW 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(2):298-312
New cationic, pentacoordinate complexes [(TPA)Rh1(ethene)]+, [1a]+, and [(MeTPA)Rh1(ethene)]+, [1b]+, have been prepared (TPA = N,N,N-tri(2-pyridylmethyl)amine, MeTPA = N-[(6-methyl-2-pyridyl)-methyl]-N,N-di(2-pyridylmethyl)amine). Complex [1a]+ is selectively converted by aqueous HCl to [(TPA)RhIII-(ethyl)Cl]+, [2a]+. The same reaction with [1b]+ results in the [(MeTPA)RhIII-(ethyl)Cl]+ isomers [2b]+ and [2c]+. Treatment of [1a]+ and [1b]+ with aqueous H2O2 results in a selective oxygenation to the unsubstituted 2-rho-da(III)oxetanes (1-oxa-2-rhoda(III)cyclo-butanes) [(TPA)RhIII(kappa2-C,O-2-oxyethyl)]+, [3a]+, and [(MeTPA)RhIII(kappa2-C,O-2-oxyethyl)]+, [3b]+. The reactivity of 2-rhodaoxetanes [3a]+ and [3b]+ is dominated by the nucleophilic character of their 2-oxyethyl oxygen. Reaction of [3a]+ and [3b]+ with the non-coordinating acid HBAr(f)4 results in the dicationic protonated 2-rhodaoxetanes [(TPA)RhIII(kappa2-2-hydroxyethyl)]2+, [4a]2+, and [(MeTPA)RhIII(kappa2-2-hydroxyethyl)]2+, [4b]2+. These eliminate acetaldehyde at room temperature, probably via a coordinatively unsaturated kappa1-2-hydroxyethyl complex. In acetonitrile, complex [4a]2+ is stabilised as [(TPA)-RhIII(kappa1-2-hydroxyethyl)(MeCN)]2+, [5a]2+, whereas the MeTPA analogue [4b]2+ continues to eliminate acetaldehyde. Reaction of [3a]+ with NH4Cl and Mel results in the coordinatively saturated complexes [(TPA)RhIII(kappa1-2-hydroxyethyl)(Cl)]+, [6a]+, and [(TPA)-RhIII(kappa1-2-methoxyethyl)(I)+, [7a]+, respectively. Reaction of [3a]+ with NH4+ in MeCN results in formation of the dicationic metallacyclic amide [(TPA)-RhIII [kappa2-O,C-2-(acetylamino)ethyl]]2+, [9]2+, via the intermediates [4a]2+, [5a]2+ and the metallacyclic iminoester [(TPA)RhIII[kappa2-N,C-2-(acetimidoyloxy)ethyl]]2+, [8]2+. The observed overall conversion of the [Rh(I)(ethene)] complex [1a]+ to the metallacyclic amide [9]2+ via 2-rhodaoxetane [3a]+, provides a new route for the amidation of a [RhI(ethene)] fragment. 相似文献
3.
Ian A. Blair Alan R. Boobis Donald S. Davies Terry M. Cresp 《Tetrahedron letters》1980,21(51):4947-4950
A convenient synthesis of N-acetyl-p-benzoquinoneimine is described, its reaction with glutathione and N-acetyl cysteine proceeds not only by adduct formation but also by a reductive pathway. 相似文献
4.
《Journal of organometallic chemistry》1989,367(3):C18-C20
Reactive CO-free monocyclopentadienylvanadium(I) complexes CpV(η2-RCCR′)(PMe3)2 (R,R′ = Ph,Ph; Ph,Me; Et,Et) can be synthesized by Mg reduction of CpVCl2(PMe3)2 in the presence of free alkyne. Reaction with a second alkyne, or use of diynes in the reduction, produces metallacycles with the metallacyclopentatriene structure. 相似文献
5.
6.
Shuai Meng Bishwa Raj Bhetuwal Padam P. Acharya 《Journal of carbohydrate chemistry》2019,38(2):109-126
Synthesis of a variety of sugar lactols (hemiacetals) has been accomplished in moderate to excellent yields by using bromine-mediated oxidation of thioglycosides. It was found that acetonitrile is the optimal solvent for this oxidation reaction. This approach involving bromine as oxidant is superior to that using N-bromosuccinimide (NBS) which produces byproduct succinimide often difficult to separate from the lactol products. 相似文献
7.
Highly nanoporous TiO(2) (anatase) spheres with an excellent ability in environmental applications have been successfully prepared via in situ hydrolysis of titanium glycolate precursor spheres. 相似文献
8.
9.
水体系中,以十六烷基三甲基溴化铵(CTAB)和L-精氨酸为表面活性剂,抗坏血酸还原PdCl42-,制得了直径范围在50~80 nm之间的辐射状钯纳米花.实验表明,CTAB和L-精氨酸对辐射状钯纳米花的形成起着协同作用.此外,还研究了辐射状钯纳米花对甲酸氧化的电催化活性.在0.5 mol/L H2SO4+0.5 mol/L HCOOH溶液中的循环伏安结果表明,辐射状钯纳米花修饰电极在酸性溶液中电催化氧化甲酸的峰电流密度约为101 mA/mg,明显优于实心钯纳米粒子修饰的电极(峰电流密度为50 mA/mg),且表现出较高的稳定性. 相似文献
10.
Metal-sulfides semiconductor nanosheets are talented entrant to be applied in electro-optic devices. Hence, the synthesis of PbS nanosheets is achieved in the current work using a simple route. The synthesized nanosheets were characterized by X-ray diffraction (XRD), FT-Raman, scanning electron microscope (SEM), UV-Visible, Photoluminescence (PL) and impedance spectroscopy techniques. XRD pattern and Raman spectrum confirms the formation of crystalline structure of PbS nanosheets. SEM study shows that the synthesized PbS is well defined nanosheets of <5 nm thicknesses. The absorption band edge is found to be remarkably blue shifted in nanosheets compare to bulk. The energy gap is calculated to be 1.16 eV which is about 3 times superior than the bulk value (0.41 eV). The enhancement of band gap indicates the occurrence of quantum confinement effect in PbS nanosheets. A strong violet emission band at ∼405 nm is observed in PL spectrum which is assigned to electrons transition from conduction-band edge to holes, ensnared at interstitial Pb2+ sites. 相似文献
11.
Hameed A Islam NU Shah MR Kanwal S 《Chemical communications (Cambridge, England)》2011,47(43):11987-11989
This communication reports facile one pot synthesis of amoxicillin and sodium salt of amoxicillin stabilized gold nanoparticles (Au-NPs). Primarily the cyclic thioether linkage i.e. the thiozolidine ring of amoxicillin is utilized for sequestering Au(III). Fluorescence quenching of these clusters makes it an efficient protocol for sensing Cu(2+) at nano scale levels. 相似文献
12.
13.
The oxidation of gem-disilylalkanes, which can be derived from 1,1-disilylethene, alkyllithiums and alkyl halides, affords the corresponding ketones. 相似文献
14.
Chung-gi Shin Yasuchika Yonezawa Kazuo Unoki Juji Yoshimura 《Tetrahedron letters》1979,20(12):1049-1050
N-Cbz-α-dehydroamino acis (DHA) were prepared by the condensation of α-keto acid with benzyl carbamate by one step and the subsequent coupling of the DHA with L-α-amino acid esters was carried out to give many kinds of dehydrodipeptides. 相似文献
15.
5‐Heteroarylthymine analogs ( 5 ) were synthesized via binucleophilic attack with bidentate thiols on the cyano group of cyanoacetylurea to form the heteroarylurea derivatives ( 2–4 ) followed by their cyclization with formamide. Also, their nucleosides 6a and 6b with 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐glucopyranose were prepared. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:209–212, 2000 相似文献
16.
3-Methoxy-N-methylmorphinan and 3-methoxy-N-methylisomorphinan reacted with osmium tetroxide to give the N-formyl compound and 15,16-dioxo-N-methyl derivative. The structure of these compounds was confirmed by chemical and physical methods. 相似文献
17.
Lynay Santacruz Silvia Donnici Albert Granados Alexandr Shafir Adelina Vallribera 《Tetrahedron》2018,74(48):6890-6895
Osmium and iridium metal nanoparticles were supported on a fluorous organic-inorganic hybrid material prepared by the sol-gel process. Moreover, we also found that the thermolysis of the Ir4(CO)12 cluster in simply diphenylether also gave Ir(0) nanoparticles. All the materials were studied as catalysts in oxidation processes. Fluoro-tagged iridium nanoparticles were particularly active in aerobic oxidation processes, whereby the catalytic activity could be greatly enhanced through a simple pre-activation procedure. With this material, benzylic alcohols could be oxidized under O2 balloon in the absence of a basic additive; the oxidative stopped selectively to the corresponding benzaldehyde. Promisingly, the same reaction conditions were used in a benzylic CH oxidation of xanthene. 相似文献
18.
Supported metallic catalysts were prepared from pyrolysis of the organometallic clusters RuOs3(CO)13(μ-H)2, Os3(CO)10(μ-AuPPh3)2, Os3(CO)12, Ru3(CO)12 and [Ru(CO)4]n, on either silica or titania, and their catalytic performance for CO oxidation has been assessed against a supported catalyst prepared from RuCl3. Ruthenium catalysts prepared from organometallic precursors were found to exhibit better activity, and that supported on TiO2 exhibited activity at the lowest operating temperature. 相似文献
19.
Dempsey JL Winkler JR Gray HB 《Dalton transactions (Cambridge, England : 2003)》2011,40(40):10633-10636
Powerful reductants [Os(II)(NH(3))(5)L](2+) (L = OH(2), CH(3)CN) can be generated upon ultraviolet excitation of relatively inert [Os(II)(NH(3))(5)(N(2))](2+) in aqueous and acetonitrile solutions. Reactions of photogenerated Os(II) complexes with methyl viologen to form methyl viologen radical cation and [Os(III)(NH(3))(5)L](3+) were monitored by transient absorption spectroscopy. Rate constants range from 4.9 × 10(4) M(-1) s(-1) in acetonitrile solution to 3.2 × 10(7) (pH 3) and 2.5 × 10(8) M(-1) s(-1) (pH 12) in aqueous media. Photogeneration of five-coordinate Os(II) complexes opens the way for mechanistic investigations of activation/reduction of CO(2) and other relatively inert molecules. 相似文献
20.
Gabriele Albertin Stefano Antoniutti Jesús Castro 《Journal of organometallic chemistry》2012,697(1):6-14
Hydrazine complexes [MCl(η6-p-cymene)(RNHNH2)L]BPh4 (1–6) [M = Ru, Os; R = H, Me, Ph; L = P(OEt)3, PPh(OEt)2, PPh2OEt] were prepared by allowing dichloro complexes MCl2(η6-p-cymene)L to react with hydrazines RNHNH2 in the presence of NaBPh4. Treatment of ruthenium complexes [RuCl(η6-p-cymene)(RNHNH2)L]BPh4 with Pb(OAc)4 led to acetate complex [Ru(κ2–O2CCH3)(η6-p-cymene)L]BPh4 (7). Instead, the reaction of osmium derivatives [OsCl(η6-p-cymene)(CH3NHNH2)L]BPh4 with Pb(OAc)4 afforded the methyldiazenido complex [Os(CH3N2)(η6-p-cymene)L}]BPh4 (8). Treatment with HCl of this diazenido complex 8 led to the methyldiazene cation [OsCl(CH3NNH)(η6-p-cymene)L}]+ (9+). The complexes were characterised spectroscopically and by X-ray crystal structure determination of [OsCl(η6-p-cymene)(PhNHNH2){PPh(OEt)2}]BPh4 (6b) and [Ru(κ2–O2CCH3)(η6-p-cymene){PPh(OEt)2}]BPh4 (7b). 相似文献