The cation [CpRu(η6-C10H8)]+ was shown to exchange naphthalene for other arenes under visible-light irradiation to form the complexes [CpRu (η6-arene)]+ (arene = C6H6, 1,4-C6H4Me2, 1,3,5-C6H3Me3, or 1,2,4,5-C 6H2Me4) in 70–95% yields. The reaction rate of exchange decreases in the series arene = 1,4-C6H4Me2 > C6H6 > 1,3,5-C6H3Me3 > 1,2,4,5-C 6H2Me4 >> C6Me6 and increases with the coordinating ability of the solvent in the order CH2Cl2 < THF—CH2Cl2 mixture (1: 1) < acetone. 相似文献
A novel, fast and easy single sample measurement has been developed based upon temperature dependence of equilibrium constant in order to determine the enthalpy and entropy changes of a complexation reaction using spectrophotometric temperature titration. The method can be used in determination of the formation constant and thermodynamic parameters of the solutions that there are difficulties in their titration where volatile compounds are studying. Knowledge of component spectra is not required for the analysis. The formation constants of the interactions of ß-di and tri-brominated meso-tetraphenylporphyrins, and meso-tetrakis(4-methylphenyl) and (4-methoxyphenyl) porphyrins with Me2SnCl2 and Bu2SnCl2, have been determined in range of 0–25 °C utilizing van’t Hoff relation, mass balance and equilibrium constant equations by an iterative least squares method with ΔH0 as adjustable parameter. The outputs of analysis are the equilibrium constants, ligand and adduct spectral profiles, their concentrations as a function of temperature, the adjusted values of the standard enthalpy ΔH0, and entropy ΔS0 changes. The order of formation constants of the resulting 1:1 complexes decreased with increasing number of bromide substituents and increased with adding methyl and methoxy groups, and vary as H2T(4-CH3O)PP > H2T(4-CH3)PP > H2TPP > H2TPPBr2 > H2TPPBr3 and Me2SnCl2 > Bu2SnCl2. 相似文献
Adsorption of CO2 as probe molecule on alkali-metal zeolites of MFI structure was investigated by joint volumetry–calorimetry. Consideration
was given to the interpretation of the heat evolved when a probe molecule is adsorbed on the surface. In particular, the number
and the strength of adsorption sites are discussed as functions of zeolite structure, concentration, and nature of extra-framework
cation. The adsorption heats (qiso) of CO2 interaction with alkali-metal cations decrease for MFI zeolite with high Si/Al in the sequence Li+ > Na+ > K+ from 54 kJ/mol to 49 and 43 kJ/mol, respectively. In addition, the adsorption heats are influenced by concentration of Al
in the framework. This phenomenon is attributed to formation of bridged CO2 adsorption complexes formed between two cations. On the base of quantitative analysis of adsorption processes, presence of
geminal adsorption complexes was suggested for adsorption at higher equilibrium pressures. 相似文献
The magnitude of chemical shift nonequivalence (Δδ) in compounds having the general formula R1CH(COOR2)N+R3Me2X? is discussed from the viewpoint of selective shielding of one of the geminal groups by the ester group in the preferred rotamer. In addition, a novel example of the increase of Δδ with rise in temperature has been observed. 相似文献
A UV-Vis spectrophotometric study of adduct formation of SalenH2 (1) and MII(Salen), where M?=?Mn (2), Fe (3), Co (4), Ni (5) and Cu (6) as donors with Me2SnCl2 as acceptor have been investigated in chloroform. Adducts (1a–6a) have been characterized by 1H, 13C and 119Sn NMR, IR and electronic spectroscopy and microanalysis. Formation constants and thermodynamic parameters were measured for 1 : 1 and 2 : 1 adducts at various temperatures (T?=?278 to 308 K). The data refinement was carried out with the SQUAD 84 program. The trend of formation constants of MII(Salen) complexes with Me2SnCl2 follows the order: Mn>Fe>Cu>Co>Ni. The formation constants for the free 1 and MII(Salen) with Me2SnCl2 changes according to the following trend: MII(Salen)>SalenH2相似文献
In order to evaluate the electron transfer ability of organocopper reagents, the reactions of appropriate Michael acceptors with methyl and butylcopper reagents were investigated. The ratio of the conjugate adduct and reduction product was used as a chemical scale for evaluating the electron transfer ability of the alkylcopper reagents. Consequently, the electron transfer ability of methyl and butylcopper reagents is in the following order; Me3CuLi2 > Me2CuLi >> Me2Cu(CN)Li2 > MeCu > MeCu(CN)Li; Bu2CuLi > BuCu(CN)Li - Bu2Cu(CN)Li2 > BuCu. 相似文献
The catalytic properties of the complexes (RCp)2ZrCl2 (R=H, Me, Pri, Bun, Bui, Me3Si,cyclo-C6H11), and Me2SiCp*NBuiZrCl2 (Cp*=C5(CH3)4) combined with the AlBui3−CPh3B(C6F5)4 cocatalyst in ethylene polymerization were studied. The specific activity of the substituted bis-cyclopentadienyl complexes
decreases in the sequence: Me>Pri>Bun>Bui>Me3Si>cyclo-C6H11, which corresponds to the activity sequence for these complexes activated by polymethylaluminoxane (MAO) but is 4–20 times
lower in absolute value. Comparison of the polyethylene samples obtained in the presence of the same complexes with MAO and
AlBui3−CPh3B(C6F5)4 cocatalysts showed that polyethylene with much higher molecular mass, melting point, and crystallinity is formed in the presence
of the ternary catalytic systems, and this indicates a different nature of the active sites of the catalytic systems. The
effective activation energy of polymerization (≈3.6 kcal mol−1), first order with respect to monomer and ≈0.4 order with respect to organoaluminum component, was found for the (PriCo)2ZrCl2−AlBui3−CPh3B(C6F5)4 catalytic system. It was proposed on the basis of the kinetic data that AliBu3 enters into the composition of the active site to form a bridged heteronuclear cationic complex.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp 301–307, February, 2000. 相似文献
Mixed ligand complexes of gold(I) with various selenones and Me3P, [Me3PAuSe=C<]Cl, have been prepared and characterized by elemental analyses, i.r. and n.m.r. methods. A decrease in the i.r. frequency
of the >C=Se mode of selenones upon complexation is indicative of selenone binding to gold(I) via a selenone group. An upfield shift in 13C-n.m.r. for the >C=Se resonance of selenones and downfield shifts in 31P-n.m.r. for Me3P moiety are consistent with the selenium coordination to gold(I). The steric effect as well as the basicity of Me3PAu+ plays a significant role in bonding with Se-containing ligands compared to the Et3PAu+ and Ph3PAu+ complexes. 相似文献
Spectroscopic Investigations on Substituent Effects in Silylmethylsilanes The silanes Me3?n(Me3SiCH2)nSiH (n = 1–3), (RMe2SiCH2)3SiH (R = n-Bu, n-Pr, Et, PhCH2, Ph) and Me3ElCH2SiMe2H (El = Ge, Sn) were prepared. The frequencies of the Si? H stretching vibration, the 29Si? 1H coupling constants and the 29Si n.m.r. chemical shifts were measured. The ?(SiH) and J(29Si? 1H) values in the silanes Me3?n(Me3SiCH2)nSiH depend on the number of trimethylsilymethyl groups. There is hardly an influence of the substituents R on these values in the silanes (RMe2SiCH2)3SiH. The frequencies of the Si? H stretching vibrations in the silanes Me3ElCH2SiMe2H (El = Si, Ge, Sn) show the order Si?Ge > Sn. The 29Si n.m.r. chemical shifts of the Si(H) signals are approximately equal in the silanes Me3?n(Me3SiCH2)nSiH and (RMe2SiCH2)3SiH. 相似文献
Direct nucleophilic displacement of iodine to give (Me3Si)3 CSiMe2 Y, where Y = F, NCO, NCS, CN or N3, takes place when (Me3Si)3 CSiMe2I is treated with solutions of CsF, KOCN, KSCN, KCN, or NaN3 in MeOH or CH3 CN. The order of effectiveness of the nucleophiles appears to be N3 > F > CN > NCS > NCO in MeOH and NCS > NCO > CN, F in CH3 CN. 相似文献
In the frame of our systematic investigation on strongly interacting alloy systems, we have measured the molar enthalpy of formation, ΔHf, of liquid Ga + Te alloy at 1200 and 1238 K by direct reaction calorimetry, using a Calvet microcalorimeter. The enthalpy of formation, with reference to the pure liquid components, is negative over the whole range of mole fractions x and has a minimum at xTe ≈ 0.6. ΔHf(l, xTe = 0.61, 1200 K) = ?(38.8 ± 0.8) kJ mol?1. This is evidence for strong chemical interactions in the liquid phase with formation of Ga2Te3 clusters. No significant difference was noted between the enthalpies at 1200 and 1238 K. Comparison of the molar integral enthalpies and entropies of formation of liquid Me0.4IIITe0.6 alloys (MeIII Al, Ga, In, and Tl) shows that the stability of the Me2Te3 clusters decreases in the series Al > Ga > In > Tl. 相似文献
The reactions of anisole with organoaluminium compounds MenAlX3−n have been investigated.The formation of a complex is the first reaction step, followed by cleavage and elimination of the gases MeX and small amounts of hydrocarbons. The yield of the gases and the cleavage rate decreases in the order: AlCl3 >/ MeAlCl2 > Me2AlCl > Me3Al and Me2AlI > Me2AlCl > Me2AlBr. For most of the investigated reactions a marked decrease in gas evolution was observed after a short period of time. This is explained by the formation of an almost inactive mixed dimer (I) which at the reaction temperature is more stable than the Me2(Cl)Al : O(Me)Ph complex. It is suggested that dimer I is formed after the intramolecular reaction of the 2 : 1 complex II after elimination of MeX. 相似文献
Quantum chemical studies using density functional theory and ab initio methods have been carried out for the molecules L-C3-L with L=PPh3 ( 1 ), NHCMe ( 2 , NHC=N-heterocyclic carbene), and cAACMe ( 3 , cAAC=cyclic (alkyl)(amino) carbene). The calculations predict that 1 and 2 have equilibrium geometries where the ligands are bonded with rather acute bonding angles at the linear C3 moiety. The phosphine adduct 1 has a synclinal (gauche) conformation whereas 2 exhibits a trans conformation of the ligands. In contrast, the compound 3 possesses a nearly linear arrangement of the carbene ligands at the C3 fragment. The bond dissociation energies of the ligands have the order 1 < 2 < 3 . The bonding analysis using charge and energy decomposition methods suggests that 3 is best described as a cumulene with electron-sharing double bonds between neutral fragments (cAACMe)2 and C3 in the respective electronic quintet state yielding (cAACMe)=C3=(cAACMe). In contrast, 1 and 2 possess electron-sharing and dative bonds between positively charged ligands [(PPh3)2]+ or [(NHCMe)2]+ and negatively charged [C3]− fragments in the respective doublet state. 相似文献
The structure of aqua complexes of alkali metal ions Me+(H2O)n, n = 1−6, where Me is Li, Na, K, Rb, and Cs, and complexes of 2,6-dimethylphenolate anion (CH3)2PhO− selected as a model of the elementary unit of phenol-formaldehyde ion exchanger with hydrated alkali metal cations Me+(H2O)n, n = 0−5, was studied by the density functional method. The energies of successive hydration of the cations and the energies
of binding of alkali metal hydrated cations with (CH3)2PhO− depending on the number of water molecules n were calculated. It was shown that the dimethylphenolate ion did not have specific selectivity with respect to cesium and
rubidium ions. The energies of hydration and the energies of binding of alkali metal cations with (CH3)2PhO− decreased in the series Li+ > Na+ > K+ > Rb+ > Cs+ as n increased. The conclusion was drawn that the reason for selectivity of phenol-formaldehyde and other phenol compounds with
respect to cesium and rubidium ions was the predomination of the ion dehydration stage in the transfer from an aqueous solution
to the phenol phase compared with the stage of binding with ion exchange groups. 相似文献
Reaction of (η5-C5Me5)Re(NO)(PPh3)(CH3) and HBF4 · OEt2 in CH2Cl2 at −78°C gives the dichloromethane complex [η5-C5Me5Re(NO)(PPh3)(ClCH2Cl)]+ BF4−, which undergoes the title transformation at −35°C. The ReClCH2Cl carbon is attacked by halide nucleophiles (X−) to give XCH2Cl and the chloride complex (η5-C5Me5)Re(NO)(PPh3)(Cl), and exhibits a 13C NMR resonance that is coupled to phosphorus (d, 3J(CP) 5.0 Hz) and geminal hydrogens (t, 1J(CH) 186 Hz). 相似文献
Summary The liquid phase oxidation of gold in donor-acceptor organic and aqueous-organic media has been studied. The compounds [AuCl(Me2S)], [AuBr(Me2S)], [AuBr3(Me2S)], [Me3S][AuBr4], [Me3S][AuBr4(Me2S)]·H2O, [Me3SO]-[AuBr4]·H2O, [Me3S][Au2Br7(Me2S)2]·3H2O, [Me3S]2-[Au2Br8]·2DMSO·H2O, [Me2(Bu)SO][AuBr4]·H2O and [Me3S]Br were isolated by dissolution of Au0 in DMSO-RX mixtures (R = H or Bu; X = Cl or Br). The products were characterized by elemental analysis and i.r. spectroscopy. The nature of the Au0-DMSO-RX systems and the oxidant species are discussed in terms of a newly-developed concept of donor-acceptor electron transport (DAET) systems. 相似文献