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1.
Rate constants for collisional removal of ã1A1 and b?1B1 CH2 and CD2 have been directly measured, using IR laser induced multiple photon dissociation to prepare the radicals, and time resolved laser induced fluorescence to observe them. For CH2(ã1A1) removal by He, Ne, Ar, Kr, Xe, N2, H2, O2, CO and CH4, rate constants of 3.1, 4.2, 6.0, 7.0, 16, 8.8, 130, 30, 56 and 73 × 10?12 cm3 molecule?1 s?1 were found respectively. These represent significant increases over the previously accepted values. Essentially no isotope effect is observed in the removal of CD2(ã1A1) by the rare gases. The rate determining step in removal by the rare gases and N2 is thought to be singlet—triplet intersystem crossing controlled by long range attractive forces, and the results are discussed in terms of both isolated and mixed state theoretical models of these processes. For the other molecular collision partners, bimolecular chemical removal channels are possible, and may account for the relatively fast rates observed. Radiative lifetimes of five Σ vibronic levels of CH2(b?1B1) and three Σ vibronic levels of CD2(b?1B1) have been measured and found to lie in the range 2.5–6.0 μs, and collisional quenching rates for CH2(b?1B1) are found to be of the order of the gas kinetic collisional frequency. 相似文献
2.
Rate constants are reported for collisional quenching of K* (4p2p and K* (5p2p) by H2O, CF4 and CH4. The K* (4p2p or K*(5p2p) is produced by photodissociation of K1 vapor at 2450 Å or 1925 Å, respectively. As for Na* (3p2p, H2O, CF4, and CH4 are very inefficient at quenching K* (4p2p); however, they are very efficient at quenching K* (5p2p). 相似文献
3.
Thomas J. Malosh Scott R. Wilson John R. Shapley 《Journal of organometallic chemistry》2009,694(20):3331-3337
The fluorocarbon soluble, binuclear ruthenium(I) complexes [Ru(μ-O2CMe)(CO)2LF]2, where LF is the perfluoroalkyl substituted tertiary phosphine, P(C6H4-4-CH2CH2(CF2)7CF3)3, or P(CH2CH2(CF2)5CF3)3, were synthesized and partition coefficients for the complexes in fluorocarbon/hydrocarbon biphases were determined. Catalytic hydrogenation of acetophenone to 1-phenylethanol in benzotrifluoride at 105 °C occured in the presence of either [Ru(μ-O2CMe)(CO)2P(C6H4-4-CH2CH2(CF2)7CF3)3]2 (1) or [Ru(μ-O2CMe)(CO)2P(CH2CH2(CF2)5CF3)3]2 (2). The X-ray crystal structure of [Ru(μ-O2CMe)(CO)2P(CH2CH2(CF2)5CF3)3]2 was determined. The compound exhibited discrete regions of fluorous and non-fluorous packing. 相似文献
4.
A series of previously unknown asymmetrical fluorinated bis(aryl)bromonium, alkenyl(aryl)bromonium, and alkynyl(aryl)bromonium salts was prepared by reactions of C6F5BrF2 or 4-CF3C6H4BrF2 with aryl group transfer reagents Ar′SiF3 (Ar′ = C6F5, 4-FC6H4, C6H5) or perfluoroorganyl group transfer reagents RF′BF2 (RF = C6F5, trans-CF3CFCF, C3F7C≡C) preferentially in weakly coordinating solvents (CCl3F, CCl2FCClF2, CH2Cl2, CF3CH2CHF2 (PFP), CF3CH2CF2CH3 (PFB)). The presence of the base MeCN and the influence of the adducts RF′BF2·NCMe (RF = C6F5, CF3C≡C) on reactions aside to bromonium salt formation are discussed. Reactions of C6F5BrF2 with AlkF′BF2 in PFP gave mainly C6F5Br and AlkF′F (AlkF′ = C6F13, C6F13CH2CH2), presumably, deriving from the unstable salts [C6F5(AlkF′)Br]Y (Y = [AlkF′BF3]−). Prototypical reactivities of selected bromonium salts were investigated with the nucleophile I-and the electrophile H+. [4-CF3C6H4(C6F5)Br][BF4] showed the conversion into 4-CF3C6H4Br and C6F5I when reacted with [Bu4N]I in MeCN. Perfluoroalkynylbromonium salts [CnF2n+1C≡C(RF)Br][BF4] slowly added HF when dissolved in aHF and formed [Z-CnF2n+1CFCH(RF)Br][BF4]. 相似文献
5.
A. Z. Kreindlin P. V. Petrovskii K. Yu. Suponitsky Z. A. Starikova 《Russian Chemical Bulletin》2009,58(4):810-816
Photolysis of a solution of Cp*RuCp (1) in CF3CO2H generates salt [CpRu(C5Me4CH2)]-(O2CCF3)(2 • O2CCF3). The reaction of compound 1 with oleum at 20 °C through the intermediate dication [η5-(CH2C5Me4)Ru(μ:η5,ν5-C5H4C5H5)Ru(C5Me4CH2)-η6]2+ leads to the triply charged cation η7CH2)2C5Me3Ru(μη5,η5-C5H4C5H4)Ru(C5Me4CH2)-η6]3+. Synthesis of pentamethylmetallocene derivatives CpMC5Me4X (M = Ru, Fe; X = CHO, CH2OH, CH2An) has been accomplished. The reactions of 1-hydroxymethyl-2,3,4,5-tetramethylruthenocene with acids CF3CO2H, HBF4, CF3CO2H/NaB[C6H3(CF3)2]4, and picric acid C6H2(NO2)3OH afforded salts 2•X (X = CF3CO2, BF4, B[C6H3(CF3)2]4), and (2,3,4,5-tetram ethylruthenocenyl)methyl picrate [CpRu(C5Me4CH2)-η6][(C6H2(NO2)3O] (2•C6H2(NO2)3O). Structure of the latter was characterized by single crystal X-ray diffraction. 相似文献
6.
The reaction of CF3Sn(CH3)3 with BCl3 and BBr3 in the presence of trimethylamine has been investigated. The volatile adducts CF2XBF2·N(CH3)3 (X = F, Cl and Br) have been isolated from the complex reaction mixture while the anions BF?4, CF2XBF?3, CF3BF2CF2X? and (CF2X)2BF?2 have been identified in the residue. [(CH3)3NH][CF2ClBF3] has been isolated. The formation of the CF2XB derivatives is likely to occur via CF2 insertion, which is promoted by the presence of N(CH3)3. NMR, IR, Raman and mass spectra of the novel fluoromethyl borane derivatives are reported. 相似文献
7.
The branching ratios for the production of Br(42P) following the broadband flash photolysis of the alkyl bromides, CH3Br and C2H5Br, and the perfluorinated molecules, CF3Br, C2F5 Br and n-C3F7 Br, have been determined using time-resolved atomic absorption spectroscopy. The production of electronically excited bromine atoms is shown to be inefficient in the case of the alkyl bromides while the perfluorinated molecules yield decreasing amounts of Br(42P) as the molecular complexity increases, i.e., CF3Br > C2F5Br > C3F5Br > C3F7. It is also shown that the hydrogenated bromides deactive electronically excited atoms almost two orders of magnitude faster than do the perfluorinated bromides. 相似文献
8.
Nathan W. Fenwick Richard Telford Amie Saidykhan William H. C. Martin Richard D. Bowen 《Molecules (Basel, Switzerland)》2021,26(16)
The accelerated formation of 2,3-diphenylquinoxalines in microdroplets generated in a nebulizer has been investigated by competition experiments in which equimolar quantities of 1,2-phenylenediamine, C6H4(NH2)2, and a 4-substituted homologue, XC6H3(NH2)2 [X = F, Cl, Br, CH3, CH3O, CO2CH3, CF3, CN or NO2], or a 4,5-disubstituted homologue, X2C6H2(NH2)2 [X = F, Cl, Br, or CH3], compete to condense with benzil, (C6H5CO)2. Electron-donating substituents (X = CH3 and CH3O) accelerate the reaction; in contrast, electron-attracting substituents (X = F, Cl, Br and particularly CO2CH3, CN, CF3 and NO2) retard it. A structure–reactivity relationship in the form of a Hammett correlation has been found by analyzing the ratio of 2,3-diphenylquinoxaline and the corresponding substituted-2,3-diphenylquinoxaline, giving a ρ value of −0.96, thus confirming that the electron density in the aromatic ring of the phenylenediamine component is reduced in the rate-limiting step in this accelerated condensation. This correlation shows that the phenylenediamine acts as a nucleophile in the reaction. 相似文献
9.
Ashley J. Pontiggia 《Journal of organometallic chemistry》2011,696(17):2870-6179
Reaction of the Ir(I)-Xantphos complex [Ir(κ2-Xantphos)(COD)][BArF4] (Xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, ArF = C6H3(CF3)2) with H2 in acetone or CH2Cl2/MeCN affords the Ir(III)-hydrido complexes [Ir(κ3-Xantphos)(H)2(L)][BArF4], L = acetone or MeCN, whereas in non-coordinating CH2Cl2 solvent dimeric [Ir(κ3-Xantphos)(H)(μ-H)]2[BArF4]2 is formed. A common intermediate in these reactions that invokes a (σ, η2-C8H13) ligand is reported. Addition of excess tert-butylethene (tbe) to [Ir(κ3-Xantphos)(H)2(MeCN)][BArF4] results in insertion of a hydride into the alkene to form [Ir(κ3-Xantphos)(MeCN)(CH2CH2C(CH3)3)(H)][BArF4], an Ir(III) alkyl-hydrido-Xantphos complex. This reaction is reversible, and heating (80 °C) results in the reformation of [Ir(κ3-Xantphos)(H)2(MeCN)][BArF4] and tbe. These complexes have been characterised by NMR spectroscopy, ESI-MS and single-crystal X-ray diffraction. They show variable coordination modes of the Xantphos ligand: cis-κ2-P,P, fac-κ3-P,O,P and mer-κ3-P,O,P with the later coordination mode like that found in related PNP-pincer complexes. 相似文献
10.
The rate coefficients for the removal of O(1D) by reaction with the following seven bromocarbons were measured using time-resolved vacuum UV atomic resonance fluorescence detection of O(3P): CH3Br, CH2Br2, CHBr3, CF3Br (Halon-1301), CF2Br2 (Halon-1202), CF2ClBr (Halon-1211), and CF2BrCF2Br (Halon-2402). The branching ratios for the quenching of O(1D) to O(3P) by the above molecules were also determined. From these measurements, the rate coefficients for reactive and nonreactive loss of O(1D) were calculated. These results are discussed in terms of their atmospheric relevance and trends in reactivity of O(1D) with hydrocarbons upon halogen substitution. © 1993 John Wiley & Sons, Inc. 相似文献
11.
The asymmetric reduction of benzophenones p-X-C6H4-CO-C6H5 (X = CH3, OCH3, Br, CF3) and p-CF3-C6H4-CO-C6H4-p'-Z (Z = CH3, Br) by chiral Grignard reagents p-Y-C6H4-CH(C2H5)CH2MgCl (Y = OCH3, CF3) gives benzhydrols of optical purities which can reach 37%. The absolute configuration of the alcohol depends on the nature of substituents. The substituent effect is discussed through donor-acceptor interactions between the aromatic nuclei in the diastereoisomeric transition states. 相似文献
12.
Atilla Karaar Volker Klaukien Matthias Freytag Holger Thnnessen Jan Omelanczuk Peter G. Jones Rainer Bartsch Reinhard Schmutzler 《无机化学与普通化学杂志》2001,627(12):2589-2603
A representative series of diphosphine monophosphonium salts [1‐Ph2P(C10H6)‐8‐PRPh2]+X– ( 2 b : R = H, X = CF3SO3; 4 : R = Me, X = CF3SO3; 5 : R = C6H5CH2 = Bn, X = Br) has been prepared by treatment of 1,8‐bis(diphenylphosphino)naphthalene (dppn, 1 ) with stoichiometric amounts of HSO3CF3 or CH3SO3CF3 in CH2Cl2 at +20 °C and with C6H5CH2Br in toluene at +80 °C. Their X‐ray crystal structures show that there is no evidence for dative P → P+ interactions. Instead, steric repulsion deflects the substituent groups to opposite faces of the naphthalene plane [splay angles: +11.4° ( 2 b ), +13.6° ( 4 ); +16.7° ( 5 )]. In solution 2 b , 4 , and 5 were dynamic according to 31P, 13C, and 1H NMR spectroscopy. The fluxionality of 2 b involves rapid intramolecular proton exchange between the two phosphorus atoms, which slows down at low temperature, whereas the dynamic behaviour of 4 and 5 is interpreted in terms of hindered rotation of the bulky RPh2P+ groups (R = Me or Bn) about the P–C(naphthyl) bond. Treatment of 1,8‐bis(diphenylphosphoryl)naphthalene (dppnO2, 6 ) with HSO3CF3 gave the protonated bis(phosphine oxide), as the triflate salt, dppnO2H+ CF3SO3– ( 7 ). The X‐ray structure analysis of 7 revealed a highly strained molecule (P1…P2 365.5 pm) in which the P=O bonds point to the same face of the naphthalene plane to accommodate the proton. All isolated compounds were characterised by a combination of 31P, 1H, and 13C NMR spectroscopy, IR spectroscopy ( 7 ), mass spectrometry and elemental analysis. 相似文献
13.
《应用有机金属化学》2017,31(2)
A set of pentacoordinated dimethyltin(IV) complexes of flexible N‐protected amino acids and fluorinated β‐diketone/β‐diketones was screened for their antibacterial activity against Pseudomonas aeruginosa , Staphylococcus aureus and Streptomyces griseus . These pentacoordinated complexes of the type Me2SnAB (where : R = CH(CH3)C2H5, A1H; CH2CH(CH3)2, A2H; CH(CH3)2, A3H; CH2C6H5, A4H; and BH = R'C(O)CH2C(O)R″: R′ = C6H5, R″ = CF3, B1H; R′ = R″ = CH3, B2H; R′ = C6H5, R″ = CH3, B3H; R′ = R″ = C6H5, B4H) were generated by the reactions of dimethyltin(IV) dichloride with sodium salts of flexible N‐protected amino acids (ANa) and fluorinated β‐diketone/β‐diketones (BNa) in 1:1:1 molar ratio in refluxing dry benzene solution. Plausible structures of these complexes were elucidated on the basis of physicochemical and spectral studies. 119Sn NMR spectral data revealed the presence of pentacoordinated tin centres in these dimethyltin(IV) complexes. 相似文献
14.
Alexander Kolomeitsev Michaela Görg Uwe Dieckbreder Enno Lork Gerd-Volker Röschenthaler 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):597-600
Abstract The System CF3I/Me3P is re-investigated and Me2PCF3, Me4P+γ, (CF3)2PMe3, Me3PI2, [Me3(CF3)P]+γ are found as products. Using CF3Br/P(NEt2)3 the phosphines R1 2PCF3 and R1P(CF3)2 (e.g. R1 = Me, iPr, NEt2) can be obtained which are precursors either for phosphoranes (e.g. 1,2λ5σ5-oxaphosphetanes) or phosphonium salts (e.g. [R1 2(Me)PCF3]+X? or [R1(Me)P(CF3)2X?]. The latter are deprotonated to furnish methylene phosphoranes R1 2(CH2=)PCF3 or R1(CH2=)P(CF3)2, reactive synthons. From CF3Br/P(NEt2)3/P(OPh)3 the phosphine P(CF3)3 is available, which turned out to be a potent electrophile. Amido phospites ROP(NEt2)2 and halides R2X (R2=CCl2CF3, X=Cl; R2=CF=CFCF3, X=F; R2=C6F5, X=Br, I; R2=C(CF3)3, X=Br; R2=SCF3, X=CF3) undergo an ARBUZOV reaction. 相似文献
15.
The methyl and ethyl chlorides and bromides, as well as methyl iodide, were photoionized in the vacuum ultraviolet at 300 K in a mass spectrometer over the pressure range 0.5 to approximately 100 millitorr. Under these conditions, stabilized parent ion dimers are found in CH3Br, CH3I, and C2H5Br, but not in the chlorides. Lower limits for the dissociative lifetimes of the ion–molecule collision complexes were estimated and are as follows: (CH3Br)2+, 1.6 μs; (CH3I)2+, 1.9 μs; and (C2H5Br)2+, 5.4 μs. An increase in photon energy (internal energy content of the reactant ion) decreases the dissociative lifetime of the collision complex in CH3I. 相似文献
16.
The mercury-photosensitized luminescence of ammonia has been investigated at low pressures. The emission spectrum with [ND3] = 0.005 torr consisted of two peaks at 305 and 340 nm. The 305 nm band was assigned to the complex in the higher electronic state which correlates with Hg(3P1). At limiting zero pressure, the complex formation in the higher state predominates, while the 340 nm band is in the ascendant at higher pressure. Results obtained in the presence of third-bodies, M = C2H6, CH4, CF4, N2, and Ne have been also reported. 相似文献
17.
Cleavage of the E-P bond in compounds of the type (CF3)2EPh2(E = P, As) is achieved by polar [HBr, (CF3)2EI, (CH3)3SnH, (CF3)2AsH] and non-polar [Br2, Mn2(CO)10] substances. Exchange reactions are possible with (CF34)E2 and P2F4 leading to the unsymmetrical compounds (CF3)2PPF2, (CF3)2AsPF2, (CF3)2PAs(CF3)2, F2PPH2, (CF3)2AsPH2. The reaction of (CF3)2PPH2 with Mn2(CO)10 gives the new binuclear complex Mn2(CO)8PH2P(CF3)2 and Mn2(CO)8[P(CF3)2]2. The hitherto unknown compound (CF3)2AsPF2 is obtained by the reaction of (CF3)2AsPH2 with P2F4. Adducts of (CF3)2PPH2 with B2H6 and (CH3)3N, respectively, are discussed. Investigation of the reaction route and characterization of most of the reaction product is based on 1H and 19F NMR spectral data. 相似文献
18.
Gabino A. Carriedo Francisco J. García Alonso Pedro A. Gonzlez 《Macromolecular rapid communications》1997,18(5):371-377
In this report we describe a very convenient synthetic method for the preparation in high yields and purity of cyclic [N3P3(OCH2CF3)6] and [N3P3(OC6H4R)6] (R = Br, CN, CHO, COC6H5, COCH3, H, OCH3), and polymeric [NP(OC6H4R)2]n (R = Br, CHO, COC6H5, H, But) phosphazenes from the direct reaction of the trimer [N3P3Cl6] or the high polymer [NPCl2]n and the alcohol HO CH2CF3 or the para-substituted phenols HO C6H4R, using Cs2CO3 as proton abstractor and acetone or tetrahydrofuran as solvent. 相似文献
19.
The fluorocarbon soluble, binuclear ruthenium(I) complexes [Ru(μ-O2CMe)(CO)2LF]2, where LF is the perfluoroalkyl substituted tertiary phosphine, P(C6H4-4-CH2CH2(CF2)7CF3)3, or P(CH2CH2(CF2)5CF3)3, were synthesized and partition coefficients for the complexes in fluorocarbon/hydrocarbon biphases were determined. Catalytic hydrogenation of acetophenone to 1-phenylethanol in benzotrifluoride at 105 °C occured in the presence of either [Ru(μ-O2CMe)(CO)2P(C6H4-4-CH2CH2(CF2)7CF3)3]2 (1) or [Ru(μ-O2CMe)(CO)2P(CH2CH2(CF2)5CF3)3]2 (2). The X-ray crystal structure of [Ru(μ-O2CMe)(CO)2P(CH2CH2(CF2)5CF3)3]2 was determined. The compound exhibited discrete regions of fluorous and non-fluorous packing. 相似文献
20.
A kinetic study of lead atoms in the spin orbit states, Pb(63P1) and Pb Pb(63P2), 0.969 and 1.320 eV, respectively, above the 63P0 ground state, has been carried out by atomic absorption spectroscopy. The electronically excited lead atoms were generated by the pulsed irradiation of lead tetraethyl and monitored photoelectrically by time-resolved attenuation of resonance radiation. The decay of the two atomic states has been studied in the presence of He, Ar, H2, D2, N2, O2, CO, NO, CO2, N2O, CH4, C2H4, C2H2 CF4, SF6, and PbEt4, and rate constants for the collisional quenching by these gases are reported. The resulting data are compared with those for the deactivation of other atomic spin orbit states of comparable energy. In general, the higher energy state, Pb(63P2), is found to be deactivated more rapidly. It would appear that the magnitude of the electronic energy to be transferred on collision governs the rates of quenching, at least where a weak interaction potential is involved, and that for most gases, deactivation of Pb(63P2) proceeds via Pb(63P1). 相似文献