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1.
(Bis‐selenolato) and (bis‐tellurolato)diiron complexes [2Fe2E(Si)] were prepared and compared with the known (bis‐thiolato)diiron complex A to assess their ability to produce hydrogen from protons. Treatment of [Fe3(CO)12] with 4,4‐dimethyl‐1,2,4‐diselenasilolane ( 1 ) in boiling toluene afforded hexacarbonyl{μ‐{[1,1′‐(dimethylsilylene)bis[methaneselenolato‐κSe : κSe]](2 ?)}}diiron(Fe? Fe) ( 2 ). The analog bis‐tellurolato complex hexacarbonyl{μ‐{[1,1′‐(dimethylsilylene)bis[methanetellurolato‐κTe : κTe]](2 ?)}}diiron(Fe? Fe) ( 3 ) was obtained by treatment of [Fe3(CO)12] with dimethylbis(tellurocyanatomethyl)dimethylsilane, which was prepared in situ. All compounds were characterized by NMR, IR spectroscopy, mass spectrometry, elemental analysis and single‐crystal X‐ray analysis. The electrocatalytic properties of the [2Fe2X(Si)] (X=S, Se, Te) model complexes A, 1 , and 2 towards hydrogen formation were evaluated.  相似文献   

2.
Cationic (arene)ruthenium‐based tetranuclear complexes of the general formula [Ru4(η6‐p‐cymene)4(μ‐NN)2(μ‐OO∩OO)2]4+ were obtained from the dinuclear (arene)ruthenium complexes [Ru2(η6p‐cymene)2(μ‐OO∩OO)2Cl2] (p‐cymene=1‐methyl‐4‐(1‐methylethyl)benzene, OO∩OO=5,8‐dihydroxy‐1,4‐naphthoquinonato(2?), 9,10‐dihydroxy‐1,4‐anthraquinonato(2?), or 6,11‐dihydroxynaphthacene‐5,12‐dionato(2?)) by reaction with pyrazine or bipyridine linkers (NN=pyrazine, 4,4′‐bipyridine, 4,4′‐[(1E)‐ethene‐1,2‐diyl]bis[pyridine]) in the presence of silver trifluoromethanesulfonate (CF3SO3Ag) (Scheme). All complexes 4 – 12 were isolated in good yield as CF3SO salts, and characterized by NMR and IR spectroscopy. The host–guest properties of the metallarectangles incorporating 4,4′‐bipyridine and (4,4′‐[(1E)‐ethene‐1,2‐diyl]bis[pyridine] linkers were studied in solution by means of multiple NMR experiments (1D, ROESY, and DOSY). The largest metallarectangles 10 – 12 incorporating (4,4′‐[(1E)‐ethene‐1,2‐diyl]bis[pyridine] linkers are able to host an anthracene, pyrene, perylene, or coronene molecule in their cavity, while the medium‐size metallarectangles 7 – 9 incorporating 4,4′‐bipyridine linkers are only able to encapsulate anthracene. However, out‐of‐cavity interactions are observed between these 4,4′‐bipyridine‐containing rectangles and pyrene, perylene, or coronene. In contrast, the small pyrazine‐containing metallarectangles 4 – 6 show no interaction in solution with this series of planar aromatic molecules.  相似文献   

3.
The compounds [2-(Me2NCH2)C6H4]2SbL (L = ONO2 ( 2 ), OSO2CF3 ( 3 )) and [PhCH2N(CH2C6H4)2]SbL (L = ONO2 ( 5 ), OSO2CF3 ( 6 )) were prepared by reacting [2-(Me2NCH2)C6H4]2SbCl ( 1 ) and [PhCH2N(CH2C6H4)2]SbCl ( 4 ), respectively, with the appropriate silver(I) salt in a 1:1 molar ratio. The new species 2 – 6 were structurally characterized in solution using multinuclear NMR and in the solid state using infrared spectroscopy. The solid-state structures for compounds 2 , 4 and 6, as well as for the hydrolysis ionic product [{2-(Me2N+HCH2)C6H4}{2-(Me2NCH2)C6H4}SbOH][CF3SO3] ( 3h ) were determined using single-crystal X-ray diffraction. Medium to strong intramolecular N→ Sb interactions were observed in all these four compounds, thus resulting in hypercoordinated organoantimony(III) species 14-Sb-6 in 2 and 10-Sb-4 in the cation of 3h and in 4 and 6 . Compounds 1 – 6 and the starting amines PhCH2NMe2 and PhCH2N(CH2C6H4Br-2)2 were investigated as catalysts in the Henry (nitroaldol) addition of nitromethane to benzaldehyde. The activity of compounds 1 – 6 resulted as an effect of the cooperation of the positively charged antimony with the negatively charged nitrogen.  相似文献   

4.
Solvolysis of [RhMe(CF3SO3)2(Me3[9]aneN3)] ( 1 ) (Me3[9]aneN3 = 1, 4, 7‐trimethyl‐1, 4, 7‐triazacyclononane) in CH3CN, DMSO or pyrazole (L) leads to substitution of both trifluoromethylsulfonate ligands and formation of the cationic complexes [RhMeL2(Me3[9]aneN3)](CF3SO3)2 3—5 . In contrast, treatment of [RuCl3(Me3[9]aneN3)] ( 2 ) with Ag(CF3SO3) in a 1:3 ratio for 2h in CH3CN leads to formation of the tetranuclear complex [{RuCl3(Me3[9]aneN3)}2Ag2(CF3SO3)(CH3CN)](CF3SO3) · CH3CN ( 6 ) with a novel [(RuCl3)2Ag2] core. More forcing conditions enable the substitution of respectively one or two chloride ligands by CH3CN (reflux 18h) or DMF (85°C, 1h) to afford [RuCl2(CH3CN)(Me3[9]aneN3)](CF3SO3) ( 7 ) and [RuCl(DMF)2(Me3[9]aneN3)](CF3SO3)2 ( 8 ). The heteroleptic sandwich complex [Ru([9]aneS3)(Me3[9]aneN3)](CF3SO3)2 ( 9 ) can be prepared by reduction of 2 with Zn powder in acetone in the presence of 3 equiv. of Ag(CF3SO3), followed by addition of [9]aneS3 (1, 4, 7‐trithiacyclononane). The redox potential E°(Ru3+/Ru2+) of +1.87 V vs NHE for 9 is only —0.12 V lower than that of the homoleptic complex [Ru([9]aneS3)2]2+. Crystal structures are reported for 3 — 9 .  相似文献   

5.
The photochemical‐induced telomerization of vinylidene fluoride (VDF) with cyclohexyl (or phenyl) trifluoromethanethiosulfonate (CF3SO2SR), leading to CF3(VDF)nSR telomers, where R stands for cyclohexyl or phenyl, is presented. These sulfurated transfer agents were synthesized by the reaction between sodium triflinate (CF3SO2Na) and disulfide in the presence of bromine. 19F NMR spectroscopy enabled an assessment of the average degrees of telomerization (DPn) of these telomers with a neat CF3 end group as the label. These DPn values increased for higher [VDF]0/[CF3SO2SR]0 initial molar ratios. Interestingly, the normal/reversed ratio of VDF units in these telomers was low. Finally, the cotelomerization of VDF and hexafluoropropylene with these transfer agents was successfully achieved, leading to original ω‐CF3 fluoroelastomers, the thermal properties of which were investigated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4538–4549, 2002  相似文献   

6.
Enantiomerically pure triflones R1CH(R2)SO2CF3 have been synthesized starting from the corresponding chiral alcohols via thiols and trifluoromethylsulfanes. Key steps of the syntheses of the sulfanes are the photochemical trifluoromethylation of the thiols with CF3Hal (Hal=halide) or substitution of alkoxyphosphinediamines with CF3SSCF3. The deprotonation of RCH(Me)SO2CF3 (R=CH2Ph, iHex) with nBuLi with the formation of salts [RC(Me)? SO2CF3]Li and their electrophilic capture both occurred with high enantioselectivities. Displacement of the SO2CF3 group of (S)‐MeOCH2C(Me)(CH2Ph)SO2CF3 (95 % ee) by an ethyl group through the reaction with AlEt3 gave alkane MeOCH2C(Me)(CH2Ph)Et of 96 % ee. Racemization of salts [R1C(R2)SO2CF3]Li follows first‐order kinetics and is mainly an enthalpic process with small negative activation entropy as revealed by polarimetry and dynamic NMR (DNMR) spectroscopy. This is in accordance with a Cα? S bond rotation as the rate‐determining step. Lithium α‐(S)‐trifluoromethyl‐ and α‐(S)‐nonafluorobutylsulfonyl carbanion salts have a much higher racemization barrier than the corresponding α‐(S)‐tert‐butylsulfonyl carbanion salts. Whereas [PhCH2C(Me)SO2tBu]Li/DMPU (DMPU = dimethylpropylurea) has a half‐life of racemization at ?105 °C of 2.4 h, that of [PhCH2C(Me)SO2CF3]Li at ?78 °C is 30 d. DNMR spectroscopy of amides (PhCH2)2NSO2CF3 and (PhCH2)N(Ph)SO2CF3 gave N? S rotational barriers that seem to be distinctly higher than those of nonfluorinated sulfonamides. NMR spectroscopy of [PhCH2C(Ph)SO2R]M (M=Li, K, NBu4; R=CF3, tBu) shows for both salts a confinement of the negative charge mainly to the Cα atom and a significant benzylic stabilization that is weaker in the trifluoromethylsulfonyl carbanion. According to crystal structure analyses, the carbanions of salts {[PhCH2C(Ph)SO2CF3]Li? L }2 ( L =2 THF, tetramethylethylenediamine (TMEDA)) and [PhCH2C(Ph)SO2CF3]NBu4 have the typical chiral Cα? S conformation of α‐sulfonyl carbanions, planar Cα atoms, and short Cα? S bonds. Ab initio calculations of [MeC(Ph)SO2tBu]? and [MeC(Ph)SO2CF3]? showed for the fluorinated carbanion stronger nC→σ* and nO→σ* interactions and a weaker benzylic stabilization. According to natural bond orbital (NBO) calculations of [R1C(R2)SO2R]? (R=tBu, CF3) the nC→σ*S? R interaction is much stronger for R=CF3. Ab initio calculations gave for [MeC(Ph)SO2tBu]Li ? 2 Me2O an O,Li,Cα contact ion pair (CIP) and for [MeC(Ph)SO2CF3]Li ? 2 Me2O an O,Li,O CIP. According to cryoscopy, [PhCH2C(Ph)SO2CF3]Li, [iHexC(Me)SO2CF3]Li, and [PhCH2C(Ph)SO2CF3]NBu4 predominantly form monomers in tetrahydrofuran (THF) at ?108 °C. The NMR spectroscopic data of salts [R1(R2)SO2R3]Li (R3=tBu, CF3) indicate that the dominating monomeric CIPs are devoid of Cα? Li bonds.  相似文献   

7.
The reactions of py‐hz ligands ( L1–L5 ) with Pb(CF3SO3)2?H2O resulted in some rare examples of discrete single‐stranded helical PbII complexes. L1 and L2 formed non‐helical mononuclear complexes [Pb L1 (CF3SO3)2]?CHCl3 and Pb L2 (CF3SO3)2][Pb L2 CF3SO3]CF3SO3?CH3CN, which reflected the high coordination number and effective saturation of PbII by the ligands. The reaction of L3 with PbII resulted in a dinuclear meso‐helicate [Pb2 L3 (CF3SO3)2Br]CF3SO3?CH3CN with a stereochemically‐active lone pair on PbII. L4 directed single‐stranded helicates with PbII, including [Pb2 L4 (CF3SO3)3]CF3SO3?CH3CN and [Pb2 L4 CF3SO3(CH3OH)2](CF3SO3)3?2 CH3OH?2 H2O. The acryloyl‐modified py‐hz ligand L5 formed helical and non‐helical complexes with PbII, including a trinuclear PbII complex [Pb3 L5 (CF3SO3)5]CF3SO3?3CH3CN?Et2O. The high denticity of the long‐stranded py‐hz ligands L4 and L5 was essential to the formation of single‐stranded helicates with PbII.  相似文献   

8.
N-Trifluoromethylsulfonyl-substituted guanidines CF3SO2N=C(NHR)2 (R = H, cyclohexyl) were synthesized in nearly quantitative yield by reactions of N-sulfinyltrifluoromethanesulfonamide CF3SO2N=S=O with urea and of trifluoromethanesulfonamide with N,N′-dicyclohexylcarbodiimide. N-[Bis(cyclohexylamino)-methylidene]trifluoromethanesulfonamide was subjected to protonation with trifluoromethanesulfonic acid and bis(trifluoromethanesulfonyl)imide, and the structure of the resulting salts and initial N-trifluoromethylsulfonylguanidines was studied by NMR and IR spectroscopy and DFT quantum-chemical calculations.  相似文献   

9.
Novel Neutral and Cationic Mono‐Aziridine Complexes of the Type [CpMn(CO)2Az], [CpCr(NO)2Az]+, and [(Ph3P)(CO)4ReAz]+ via CO‐, Hydride‐, and Chloride‐Elimination Reactions The monoaziridine complexes 1 — 5 are obtained by three differently induced substitution reactions. The photolytically induced CO substitution reaction of [CpMn(CO)3] with 2, 2‐dimethylaziridine leads to the neutral N‐coordinate aziridine complex [Cp(CO)2Mn{$\overline{N(H)CMe2C}$ H2}] ( 1 ). The protonation of [(Ph3P)(CO)4ReH] with CF3SO3H and consecutive treatment with 2, 2‐dimethylaziridine or 2‐ethylaziridine gives the salt‐like aziridine complexes [(Ph3P)(CO)4Re{$\overline{N(H)CMe2C}$ H2}](CF3SO3) ( 2 ) or [(Ph3P)(CO)4Re{ H2}](CF3SO3) ( 3 ) by hydride elimination reactions. The like‐wise salt‐like complexes [Cp(NO)2Cr{$\overline{N(H)CMe2C}$ H2}](BF4) ( 4 ) and [Cp(NO)2Cr{ H2}](CF3SO3) ( 5 ) are synthesized from [CpCr(NO)2Cl] by chloride elimination with AgX (X = BF4, CF3SO3) in the presence of 2, 2‐dimethylaziridine or 2‐ethylaziridine, respectively. As a result of X‐ray structure analyses, the metal atoms are trigonal pyramidally ( 1, 4, 5 ) or octahedrally ( 2, 3 , cis‐position) configurated; the intact three‐membered rings coordinate through the distorted tetrahedrally configurated N atoms. All compounds 1‐5 are stable with respect to the directed thermal alkene elimination to give the corresponding nitrene complexes; the IR, 1H‐ and 13C{1H}‐NMR, and MS spectra are reported and discussed.  相似文献   

10.
Investigating the synthesis and properties of diiron azadithiolate complexes is one of the key topics for mimicking the active site of [FeFe]‐hydrogenases, which might be very useful for the design of new efficient catalysts for hydrogen production and the development of a future hydrogen economy. A series of new phosphine‐substituted diiron azadithiolate complexes as models for the active site of [FeFe]‐hydrogenases are described. A novel and efficient way was firstly established for the preparation of phosphine‐substituted diiron azadithiolate complexes. The reaction of Fe2(μ‐SH)2(CO)6 and phosphine ligands L affords the intermediate Fe2(μ‐SH)2(CO)5L ( A ). The intermediate reacts in situ with a premixed solution of paraformaldehyde and ammonium carbonate to produce the target phosphine‐substituted diiron azadithiolate complexes Fe2[(μ‐SCH2)2NH](CO)5L ( 1a – 1f ) (L = P(C6H4–4‐CH3)3, P(C6H4–3‐CH3)3, P(C6H4–4‐F)3, P(C6H4–3‐F)3, P(2‐C4H3O)3, PPh2(OCH2CH3)). Furthermore, reactions of the intermediate A with I‐4‐C6H4N(CH2Cl)2 in the presence of Et3N give the phosphine‐substituted diiron azadithiolate complexes Fe2[(μ‐SCH2)2NC6H4–4‐I](CO)5L ( 2a – 2e ) (L = P(C6H4–4‐CH3)3, P(C6H4–3‐CH3)3, P(C6H4–4‐F)3, P(C6H4–3‐F)3, P(2‐C4H3O)3). All the complexes were fully characterized using elemental analysis, IR and NMR spectroscopies and, particularly for 1a , 1c – 1e , 2a and 2c , single‐crystal X‐ray diffraction analysis. In addition, complexes 1a – 1f and 2a – 2e were found to be catalysts for H2 production under electrochemical conditions. Density functional theory calculations were performed for the reactions of Fe2(μ‐SH)2(CO)6 + P(C6H4–4‐CH3)3.  相似文献   

11.
Treatment of the digallium compound R2Ga–GaR2 [ 1 , R = CH(SiMe3)2] with a broad variety of functionalized carboxylic acids in the presence of water yielded μ‐hydroxo‐μ‐carboxylatodigallium compounds ( 2 – 10 ) containing intact Ga–Ga bonds in high to moderate yields. The compounds form dimeric formula units in which the unsupported Ga–Ga bonds are bridged by two hydroxo and two carboxylato ligands. Each gallium atom is terminally coordinated by a bulky alkyl group. NMR spectroscopy revealed mixtures of two isomeric compounds in solution in all cases. The second component may show a different bridging mode with each Ga–Ga bond bridged by a bidentate carboxylato ligand to form Ga2O2C five‐membered heterocycles.  相似文献   

12.
The self‐assembly of 2,4,6‐tris(pyridin‐4‐yl)‐1,3,5‐triazine (tpt) triangular panels with p‐cymene–ruthenium building blocks and 5,8‐dioxido‐1,4‐naphthoquinonato (donq) bridges, in the presence of pyrenyl‐containing dendrimers of different generations (P0, P1 and P2), affords the triangular prismatic host–guest compounds [Pn?Ru6(p‐cymene)6(tpt)2(donq)3]6+ ([Pn? 1 ]6+). The host–guest nature of these systems, with the pyrenyl moiety being encapsulated in the hydrophobic cavity of the cage and the dendritic functional group pointing outwards, was confirmed by NMR spectroscopy (1H, 2D and DOSY). The host–guest properties of these systems were studied in solution by NMR and UV/Vis spectroscopic methods, allowing the determination of their affinity constants (Ka). Moreover, the ability of these water‐soluble host–guest systems to carry the pyrenyl‐containing dendrimers into cancer cells was evaluated on human ovarian cancer cells. The host–guest systems are all more cytotoxic than the empty cage [ 1 ][CF3SO3]6 (IC50≈4 μM ), with the most active compound, [P0? 1 ][CF3SO3]6, being an order of magnitude more cytotoxic.  相似文献   

13.
MgO-MgAl2O4 nanocomposite was prepared from the co-precipitation of Mg(NO3)2 and Al(NO3)3 salts, characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and fourier transform infrared spectroscopy (FTIR) techniques and evaluated in the synthesis of thirty five derivatives of benzo[4,5]thiazolo[3,2-a]chromeno[4,3-d]pyrimidin-6-ones (d1-d34) via the multi-component reaction of 4-hydroxycoumarins, aldehydes, and 2-aminobenzothiazole derivatives under solvent free condition. The catalytic activity of MgO-MgAl2O4 nanocomposite and the synthesis of the above mentioned compounds were investigated under thermal solvent free (times: 1.4–3 h; yields: 75–95%), ultrasonic irradiation (US) conditions (times: 1–2.5 h; yields: 69–97%) and using high-speed ball milling (HSBM) technique (times: 0.7–2.5 h; yields: 67–97%). In all cases, the products were obtained in excellent yields. Nuclear Magnetic Resonance (NMR) and MASS spectroscopy were used to characterize the structure of the desired product. The mechanism for the preparation of compounds d1-d34 was proposed and confirmed by 1H NMR investigations.  相似文献   

14.
The water-soluble complex [RuClCp(PPh3)(mPTA)](CF3SO3) reacts with the thiopurines, bis(S-8-thiotheophylline)methane (MBTTH2), 1,2-bis(S-8-thiotheophylline)ethane (EBTTH2), and 1,3-bis(S-8-thiotheophylline)propane (PBTTH2), to lead to the binuclear ruthenium(II) complexes [{RuCp(PPh3)(mPTA)}2-μ-(LS7,S′7)](CF3SO3)2 where (L = MBTT2? (1), EBTT2? (2), and PBTT2? (3)). All the complexes have been fully characterized by elemental analysis, IR, and multinuclear 1H, 13C{1H}, and 31P{1H} NMR spectroscopy. The cyclic voltammetry of the complexes is characterized by two one-electron oxidative responses (RuII–RuII/RuIII–RuII; RuIII–RuII/RuIII–RuIII) that increase their redox potential when the bis(8-thiotheophylline)-alkyl-bridge growths. The reactivity against DNA and partition coefficient of the complexes were also determined.  相似文献   

15.
A square-planar coordination geometry was found for the complex [Ir(cod){(?)-norphos}][PF6] ( 1b [PF6]; cod = cylcoocta-1,5-diene and (?)-norphos = [(2R,3R)-8-9-10-trinorborn-5-ene-2,3-diyl]bis(diphenylphosphine)) in the solid state by X-ray diffraction. Crystal data: monoclinic, space group P21, a = 10.751 (6), b = 18.669(14), c = 12.037(8) Å, β = 114.82(5)°, Z = 2. A total structural assignment including the configurational and conformational aspects of this and the related compounds [Ir(bishosphine)(cod)]X (bisphosphine = (?)-chiraphos = (2S,3S)-2,3-bis(diphenylphosphino)butane and (?)-norphos, X = Cl, CF3SO3, or PF6) was carried out in solution by one- and two-dimensional NMR spectroscopy. The complexes containing the CF3SO3? and PF6? anions are four-coordinate cations with square-planar geometry, whereas the chlorides are five-coordinate neutral compounds showing solvent-dependent dynamic behaviour. In toluene, two diastereoisomers of [IrCl(cod){(?)-norphos}] ( 2b ) exist and interconvert slowly at room temperature. This interchange is fast in CDCl3 solution, and it is likely to involve Cl dissociation and the formation of the cation [Ir(cod){(?)-norphos}]+ as an intermediate.  相似文献   

16.
Hydrido complexes [MnH(CO)3L1–3] [L1 = 1,2‐bis‐(diphenylphosphanoxy)‐ethane ( 1 ); L2 = 1,2‐bis‐(diisopropylphosphanoxy)ethane ( 2 ); L3 = 1,3‐bis‐(diphenylphosphanoxy)‐propane ( 3 )] were prepared by treating [MnH(CO)5] with the appropriate bidentate ligand by heating to reflux. Photoirradiation of a toluene solution of complexes 1 and 2 in the presence of PPhn(OR)3–n (n = 0, 1; R = Me, Et) leads to the replacement of a CO ligand by the corresponding monodentate phosphite or phosphonite ligand to give new hydrido compounds of formula [MnH(CO)2(L1–2)(L)] [L = P(OMe)3 ( 1a – 2a ); P(OEt)3 ( 1b – 2b ); PPh(OMe)2 ( 1c – 2c ); PPh(OEt)2 ( 1d – 2d )]. All complexes were characterized by IR, 1H, 13C and 31P NMR spectroscopy. In case of compounds 2 and 3 , suitable crystals for X‐ray diffraction studies were isolated.  相似文献   

17.
Reaction of organotin(IV) chloride(s) with 2-benzoylpyridine-N(4)-cyclohexylthiosemicarbazone, [HL] (1) yielded [MeSnCl2(L)] (2), [BuSnCl2(L)] (3), [Me2SnCl(L)] (4), and [Ph2SnCl(L)] (5). The ligand (1) and its organotin(IV) complexes have been characterized by CHN analyses, molar conductivity, UV-Vis, FT-IR, 1H, 13C, and 119Sn NMR spectral studies. The molecular structure of 5 was also determined by X-ray diffraction. There are two independent molecules in the asymmetric unit and the central tin(IV) atom is six-coordinate in distorted octahedral geometry. The ligand (1) and complexes were screened for their in vitro antibacterial activities. The cytotoxic activities of 15 were tested against A2780 and A2780/Cp8 cancer cell lines. The compounds have better antibacterial activities than the free ligand; 25 are more potent cytotoxic agents than 1, while the diphenyltin(IV) 5 is more active with IC50 values of 0.05 and 0.54?µmol?L?1 against A2780 and A2780/Cp8 cell lines, respectively.  相似文献   

18.
The electroreduction of the halofluoromethanes CF3Br, CF2Br2 and CF2BrCl has been studied in high‐pressure stainless steel autoclaves at different cathodes [Pt, steel (V2A, V4A), glassy carbon (GC)] and in various solvent‐supporting electrolyte systems (SSE), e.g. DMF/[Bu4N]Br, NMP/[Bu4N]BF4 etc. The reduction potentials for CF3Br increase from Pt (–1.6 V) < V2A (–1.8 V) < GC (–2.1 V) and are lower for CF2Br2 and CF2BrCl suggesting a reductive cleavage of C‐X bonds as the first step. CF2Br2 and CF2BrCl show a two‐step reduction in accord with the C–X bond energies (C–F > C–Cl > C–Br) and the “Perfluoro‐effect”. The electrolysis of CF3Br in different SSE‐systems with sacrificial zinc or cadmium anodes has been reinvestigated with our experimental set‐up to elucidate the influence of the experimental conditions on the type and ratio of the products. The observed products CF3MBr·42L and (CF3)2M·42L (M = Zn, Cd; L = DMF or AN) are the same as in the previous investigations, but are obtained in different ratios, as a rule caused by a parallel chemical corrosion of the respective anodes. By using aluminium as sacrificial anode no CF3Al compounds are formed. The CF3 species generated by electroreduction of CF3Br react with the solvents via hydrogen abstraction and formation of CF3H. The current yield with respect to the dissolution of the Al anode reaches 120 % indicating a considerable chemical corrosion in addition to the anodic oxidation. This result enabled a one‐pot trifluoromethylation reaction of NMP as organic carbonyl substrate and solvent with CF3Br and aluminium powder (ratio 3 : 2) at higher temperatures (> 70 °C). The complete reaction of CF3Br to give CF3H and 1‐methyl‐2‐trifluoromethyl‐4,5‐dihydropyrrol allowed the isolation of the latter by vacuum condensation and distillation in 45 % yield, rel. to the CF3Br used. Gallium and indium were also applied as sacrificial anodes in combination with CF3Br as substrate. In both cases, anodic current yields of about 280 % indicated an extreme chemical corrosion together with cathodic metal depositions corresponding to the cathodic current yield. These deposits – in contrast to those of Zn and Cd – do not react with CF3Br in Grignard‐type conversions to CF3Ga and CF3In compounds. So, the observed products (CF3)nMBr3–n·L (M = Ga, In; n 1‐3; L = DMF, NMP) are obviously formed by chemical corrosion of the electro‐activated anodes. Finally, electrochemical and chemical trifluoromethylations were successfully carried out, using R3SiCl (R = Me, Vi, Ph), Me3M′Cl (M′ = Ge, Sn) and aluminium anodes or Al‐powder. The products were characterized either after isolation or in the product solutions by NMR‐spectroscopic investigations.  相似文献   

19.
The new PPA ligands 3-[5-methyl-3-(trifluoromethyl)-1H-pyrazol-1-yl]propanamide (CF3MePPA; 3 ) and 3-[3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl]propanamide ((CF3)2PPA; 4 ) were synthesized by Aza-Michael addition of the specific pyrazole derivatives to acrylamide. Both products were characterized by elemental analyses, IR and NMR spectroscopy, and mass spectrometry. X-Ray structure determination of 3 revealed the presence of a one-dimensional hydrogen-bonded structure in the solid state. The ligating ability of the new ligands towards PdCl2 was studied, showing that 3 behaves similar to Me2PPA and reacts cleanly with PdCl2 to afford the sparingly soluble complex PdCl2(CF3MePPA-κN)2. By contrast, the donor ability of pyrazolyl group in 4 was found to be considerably reduced, thus resulting in the formation of the unusual complex PdCl2{(CF3)2PPA-κN}{(CF3)2PPA-κO}.  相似文献   

20.
Phosphoranides are interesting hypervalent species which serve as model compounds for intermediates or transition states in nucleophilic substitution reactions at trivalent phosphorus substrates. Herein, the syntheses and properties of stable trifluoromethylphosphoranide salts are reported. [K(18-crown-6)][P(CF3)4], [K(18-crown-6)][P(CF3)3F], and [NMe4][P(CF3)2F2] were obtained by treatment of trivalent precursors with sources of CF3 or F units. These [P(CF3)4-nFn] (n=0–2) salts exhibit fluorinating (n=1–2) or trifluoromethylating (n=0) properties, which is disclosed by studying their reactivity towards selected electrophiles. The solid-state structures of [K(18-crown-6)][P(CF3)4] and [K(18-crown-6)][P(CF3)3F] are ascertained by single crystal X-ray crystallography. The dynamics of these compounds are investigated by variable temperature NMR spectroscopy.  相似文献   

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