The polymerization of vinyl acetate in N,N-dimethylformamide (DMF) at 60°C initiated by AIBN in the presence of [Fe(DMF)6](ClO4)3 and Fe(N3)3 had been studied. Fe(N3)3 was produced in situ by mixing solid sodium azide (NaN3) and hexakis(N,N-dimethylformamide) iron (III) perchlorate, [Fe(DMF)6](ClO4)3, in the ratio of 3:1. The velocity constant kx for the interaction of poly(vinyl acetate) radical with [Fe(DMF)6]3+ was found to be 1.44 × 103L mol?1 s?1 and that for the interaction of poly(vinyl acetate) radical with Fe(N3)3 to be 3.44 × 105 L mol?1 s?1 at 60°C. 相似文献
Kinetics of 2,2′-azobisisobutyronitrile initiated polymerization of styrene in N,N-dimethylformamide (DMF) were investigated in the presence of dichloro bis(N,N-dimethylformamide)copper(II) complex. The complex was prepared in situ by mixing tetrakis(N,N-dimethylformamide)copper(II) perchlorate with LiCl in the molar ratio of 1:2. The equilibrium constant for was calculated by the limiting logarithmic method as 1.07 × 1010 l2 mol?2. The velocity constant at 60 for the interaction of polystyryl radical with Cu(DMF)2Cl2 is 2.16 × 104 l. mol?1 sec?1. 相似文献
The polymerization of styrene initiated by 2,2′-azobisisobutyronitrile has been studied in N,N-dimethylformamide solution at 60°C in the presence of hexakis(N,N-dimethylformamide) iron(III) tetrafluoroborate alone, and also in the presence of added lithium chloride. The presence of Fe(DMF)63+ ions in the polymerizing systems caused retardation, but iron(III) chloro complexes produced well defined inhibition periods. Velocity constants at 60°C for polystyryl radicals towards Fe(DMF)63+, Fe(DMF)5Cl2+, Fe(DMF)4Cl2+, and FeCl4? ions were calculated to be 847, 4.15 × 104, 6.55 × 104, and 3.14 × 104 l./mole-sec, respectively. Values of the initiator efficiency f for most systems investigated ranged from 0.59 to 0.62. 相似文献
Strongly enhanced N2 first positive emission N2(B 3Πg → A 3Σ+u) has been observed on addition of N atoms into a flowing mixture of Cl and HN3. The dependence of the emission intensity on N atom concentration gave a rate constant for the reaction N + N3 → N2(B 3Πg) + N2(X 1Σ+g) of i(1.6 ± 1.1) × 10?11 cm3 molecule?1 s?1. That for the reaction Cl + HN3 → HCl + N3 is (8.9 ± 1.0) × 10?13 cm3 molecule?1 s?1 from the decay of the emission. Comparison of the emission intensity in ClHN3 with that in ClHN3N gave the rate constant of the reaction N3 + N3 → N2(B 3Πg) + 2N2(X 1Σ+g) as 1.4 × 10?12 cm3 molecule?1 s?1 on the assumption that N + N3 yields only N2(B 3Πg) + N2(X 1Σ+g). 相似文献
The reaction chemistry of C2N2? Ar and C2N2? NO? Ar mixtures has been investigated behind incident shock waves. Progress of the reaction was monitored by observing the cyano radical (CN) in absorption at 388.3 nm. A quantitative spectroscopic model was used to determine concentration histories of CN. From initial slopes of CN concentration during cyanogen pyrolysis, the rate constant for C2N2 + M → 2CN + M (1) was determined to be k1 = (4.11 ± 1.8) × 1016 exp(?47,070 ± 1400/T) cm3/mol · s. A reaction sequence for the C2N2? NO system was developed, and CN profiles were computed. By comparison with experimental CN profiles the rate constant for the reaction CN + NO → NCO + N (3) was determined to be k3 = 10(14.0 ± 0.3) exp(?21,190 ± 1500/T) cm3/mol · s. In addition, the rate of the four-centered reaction CN + NO → N2 + CO (2) was estimated to be approximately three orders of magnitude below collision frequency. 相似文献
Contributions to the Chemistry of Halosilane Adducts. XVI. Synthesis, Properties, Crystal and Molecular Structure of Hexa(N,N-dimethylformamide)silicon(IV)-tetraiodide When SiI4 is reacted with DMF ionization of all SiI bonds occurs to give ( 2 ) (reaction of pure components) or ( 1 ) (CHCl3 solution). IR and 1H-NMR spectra are in accordance with the formation of the octahedral cation [Si · 6 DMF]4+, DMF being coordinated through the CO group. 1 is only slowly attacted by methanol or water DMF being liberated. 1 crystallizes in the monoclinic space group C2/c with 4 formula units per unit cell. The cation [Si · 6 DMF]4+ has 1 symmetry. DMF is coordinated to Si in trans-configuration with respect to NMe2 with donation by oxygen. SiO bond distances (175.4–177.2 pm) correspond to those of [Si(O2C6H4)3]2? and [Si(acac)3]+; an increase of the CO distances (126.1–128.9 pm) and decrease of the CN distances (126.4–129.1 pm) as compared to free DMF is observed. These changes and structural data are discussed. 相似文献
The rate constant of the gas-phase reaction Fe(a5D4) + CO2 at 1180–2380 K and a total gas density of (7.0–10.0) × 10?6 mol/cm3 behind incident shock waves is k(Fe + CO2) = 1.4 × 1014.0 ± 0.3exp[?(14590 ± 1100)/T] cm3 mol?1 s?1, as determined by resonance atomic absorption photometry. Using thermochemical data available from the literature, the rate constant of the reverse reaction was calculated to be k(Fe + CO) = 9.2 × 1011.0 ± 0.3 (T/1000)0.57exp[?(490 ± 1100)/T] cm3 mol?1 s?1. The results are compared with data reported earlier. 相似文献
The title compound, potassium bis(ethylenediamine‐N,N′)copper(II) hexacyanoferrate(III), K[Cu(C2H8N2)2]‐[Fe(CN)6], contains [Cu(en)2]2+ and [Fe(CN)6]3? complex ions, where en is ethylenediamine. The FeIII and K+ ions lie on twofold axes and the CuII atom lies on an inversion center. The [Cu(en)2]2+ ion has square‐planar coordination with a mean Cu—N distance of 1.992 (2) Å and the [Fe(CN)6]3? ion has distorted octahedral coordination with a mean Fe—C distance of 1.947 (2) Å. 相似文献
High-pressure 1H-NMR. has been used to determine volumes of activation (ΔV#) for solvent exchange with [M(S)6]3+ ion (M = Al(III), Ga(III); S = dimethylsulfoxide (DMSO) and N,N-dimethylformamide (DMF)) in [2H]3-nitromethane solution. For Al(III),Δ V# = + 15.6 ± 1.4 (S = DMSO, 358.5 K) and ΔV# = + 13.7 ± 1.2 cm3mol?1 (S = DMF, 354.5 K), whilst for Ga(III), ΔV# = + 13.1 ± 1.0 (S = DMSO, 334.6 K) and ΔV# = +7.9 ± 1.6 cm3mol?1 (S= DMF, 313.8 K). Variable temperature studies over a temperature range of 107.2 K (Al(III)) and 101.1 K (Ga(III)) were carried out for solvent exchange with [M(DMF)6]3+ ions in [2H]3-nitromethane solution, using stopped-flow NMR, and conventional linebroadening, and gave ΔH# = 88.3 ± 0.9 and 85.1 ± 0.6 kJ+ mol?1, and ΔS# = 28.4 ± 2.7 and 45.1 ± 1.9 JK?1 mol?1 for Al(III) and Ga(III) ions respectively. All of these results are consistent with dissociative modes of activation. 相似文献
A novel complex, [Pr(5-nip)(phen)(NO3)(DMF)] (5-nip: 5-nitroisophthalic acid; phen: 1,10-phenanthroline, DMF: N,N-dimethylformamide), was prepared and characterized by single crystal X-ray diffraction, elemental analysis, IR spectrum and DTG-DSC techniques. The results show that the crystal is monoclinic, space group P2(1)/n with a=11.0876(6) Å, b=12.8739(7) Å, c=16.9994(8) Å; β=91.193(4)°, Z=4, Dc=1.822 Mg m–3, F(000)=1320. Each Pr(III) ion is nine-coordinated by one chelating bidentate and two monodentate bridging carboxylate groups, one chelating bidentate nitryl group, one DMF molecule and one 1,10-phenanthroline molecule. The complex is constructed with one-dimensional ribbons featuring dinuclear units and the one-dimensional ribbons are further assembled into two-dimensional networks by strong π–π stacking interactions. The complex has high stability up to 500°C. The enthalpy change of formation of the compound in DMF was measured using an RD496-III type microcalorimeter with the value of –9.214±0.173 kJ mol–1. 相似文献
The complexation reaction between Eu3+, La3+, Er3+ and Y3+ cations with the dicyclohexyl-18-crown-6 (DCH18C6) in acetonitrile (AN)–dimethylformamide (DMF) and AN–methanol (MeOH) binary systems have been studied at different temperatures using conductometric method. The conductometric data show that the stoichiometry of the complexes is 1:1 [ML]. The results show that the stability constant of complexes in various solvents is: AN > MeOH > DMF. In the some cases, the minimum of logKf for (DCH18C6–Eu3+), (DCH18C6–La3+), (DCH18C6–Er3+) and (DCH18C6–Y3+) complexes in AN–MeOH binary systems obtain at χMeOH ~ 0.75, and also, the logKf of (DCH18C6–Er3+) complex in AN–DMF binary systems show a minimum at χAN ~ 0.75. Non-linear behavior was observed for the stability constant of complexes versus the composition of the solvent systems. The experimental data show that the selectivity order of DCH18C6 for these cations in AN–MeOH binary systems (mol% AN = 50, 75) at 25 °C is: Y3+ > Er3+ > Eu3+ > La3+. The values of thermodynamic parameters (?H?C) for formation of complexes were obtained from temperature dependence of stability constants of complexes using the van′t Hoff plots and the standard entropy (?S?C) were calculated from the relationship: ?G?C, 298.15 = ?H?C ?298.15?S?C. The results show that the values of these thermodynamic parameters are influenced by the nature and the composition of the binary systems. 相似文献
Methyl methacrylate (MMA) can be polymerized by the charge-transfer complex formed by the interaction of melamine (MM), MMA and carbon tetrachloride in a non-aqueous solvent like dimethyl sulphoxide (DMSO) or N-N-dimethylformamide. The polymerization can be accelerated by Lewis acids like Fe3?. This paper reports the polymerization of MMA initiated by MM and CCl4 and accelerated with hexakis dimethylsulphoxide iron(III) perchlorate [Fe(DMSO)6] (ClO4)3. A, at 60°. Induction periods were observed for the polymerization initiated by MM and CCl4 alone, but not when the molar ratio of MM to A became 3:1. The molecular weights of the polymers with 3:1 molar ratio of MM to A were higher than with MM alone. The rate constant for the polymerization of MMA in presence of [Fe(MM)3]3+ was 1.4181 × 10?5 1 mol?1 sec?1 at 60°. The transfer constant for CCl4, in the absence of A, is 4.66 × 10?3. 相似文献
The copper-catalyzed oxidation of hydrazine by iron(III) in acid solution follows the rate law -d[Fe(III)]/dt = kKh[Cu(II)]2/(Kh + [H+]), where Kh is the hydrolysis constant of Cu2+, k was found to be 8.8±0.8, 13.2±1.4 and 17.5±1.3 min?1 at 35, 40, and 45°C respectively and μ= 0.2 mol/L. The composition of the activated complex is Cu2+, CuOH+, N2H4, H+ or others. Perhaps several hydrazine complexes of Cu(II) participate in the reaction and one of them isolated was Cu(N2H4)2(HSO4)2. Study on the oxidation of this complex is also in conformity with the above rate law. 相似文献
The electrochemical reduction of SO2 in dimethylformamide at Pt electrodes finally leads to the red species S3O2?6 via the blue complex S2O·?4. The UV-VIS absorption coefficients are determined: ?(S2O·?4) = (224 ± 25) × 105 cm2 mol?1; ?(S3O2?6) = (0.64 + 0.07) × 105 cm2 mol?1. A calculation of the complexing constant of SO2 with free SO·?2 radical based on potential shifts confirms this constant to be in the range of 200–700 1 mol?1.Two potentiometric titration methods (viz: with allylbromide and tetraethylammoniumtribromide) for analysis of electrolytically generated SIII-oxo-anions in DMF are presented. Reactions of those anions with aromatic aldehydes and trials for trapping of possibly formed SO are described. 相似文献
Methyl methacrylate (MMA) can be polymerized by a charge transfer complex formed by the interaction of urea, methyl methacrylate, and carbon tetrachloride (CCl4) in a nonaqueous solvent like dimethylsulfoxide (DMSO). The rate of polymerization can be accelerated by Lewis acids like Fe3+. This article reports the polymerization of MMA initiated by urea and CCl4 and accelerated with hexakisdimethylsulfoxide iron (III) perchlorate, [Fe(DMSO)6](ClO4)3, and A at 60°C. Definite induction periods were observed for the polymerization reaction initiated by urea and CCl4 alone, but the induction period completely vanished when the molar ratio of urea to A reached 6:1. The molecular weights of the polymers with 6:1 molar ratio of urea to A were higher than with urea alone. The rate constant for the polymerization of MMA in the presence of [Fe(urea)6]3+ was 1.03 × 10?5 1 mol?1 s?1 at 60°C. The transfer constant for CCl4 for polymerization with urea alone is 2.43 × 10?3 at 60°C. 相似文献
The reactions of three polypyridylamine ferrous complexes, [Fe(TPEN)]2+, [Fe(TPPN)]2+, and [Fe(TPTN)]2+, with nitric oxide (NO) (where TPEN = N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine, TPPN = N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,2-propylenediamine, and TPTN = N,N,N′,N′-tetrakis(2-pyridylmethyl)trimethylenediamine) were investigated. The first two complexes, which are spin-crossover systems, presented second-order rate constants for complex formation reactions (kf) of 8.4 × 103 and 9.3 × 103 M?1 s?1, respectively (pH 5.0, 25 °C, I = 0.1 M). In contrast, the [Fe(TPTN)]2+ complex, which is in low-spin ground state, did not show any detectable reaction with NO. kf values are lower than those of high-spin Fe(II) complexes, such as [Fe(EDTA)]2? (EDTA = ethylenediaminetetraacetate) and [Fe(H2O)]2+, but higher than low-spin Fe(II) complexes, such as [Fe(CN)5(H2O)]3? and [Fe(bipyridine)3]2+. The release of NO from the [Fe(TPEN)NO]2+ and [Fe(TPPN)NO]2+ complexes were also studied, showing the values 15.6 and 17.7 s?1, respectively, comparable to the high-spin aminocarboxylate analogs. A mechanism is proposed based on the spin-crossover behavior and the geometry of these complexes and is discussed in the context of previous publications. 相似文献
Single crystals of the title complex, tris(1,6‐dihydro‐9H‐purine‐6‐thione‐N7,S)iron(II) tetrachloroferrate(III) chloride, [Fe(C5H4N4S)3][FeCl4]Cl, were grown on the surface of solid 6‐mercaptopurine monohydrate pellets in a solution of iron(III) chloride. The solution of the hexagonal structure required the application of twin refinement techniques. All the component ions lie on threefold rotation axes. The complex contains distorted octahedral [Fe(C5H4N4S)3]2+ cations with three N7/S6‐chelating neutral 6‐mercaptopurine ligands, tetrahedral [FeCl4]? anions with a mean Fe—Cl distance of 2.189 (1) Å, and free chloride ions. 相似文献