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All total 5 Articles be foundThermal stability of quaternary ammonium hexafluorophosphates and halides
Zhuravlev,Nikol'skii,Voronchikhina
, p. 824 - 830 (2014/02/14)
Thermal decomposition of hexafluorophosphates of short-chain tetraalkylammonium salts of the general formula R3R'NPF6, where R3 = R' = CH3, C2H5, C 4H9; R3 = C2H5, R' = CH2C6H6 or CH2CH=CH2, was studied by thermal gravimetric analysis. Measurements were performed in air in the temperature interval 20-500°N. The thermal stability of halides with the same cations in the same temperature interval was studied for comparison. The effect of cation on the thermal stability of the halides and hexafluorophosphates was examined. The mechanism of thermal decomposition of quaternary ammonium hexafluorophosphates was suggested.
Synthesis, structural characterization, and properties of the [Mo2O2S9]2- thio anion and the [Mo4O4S18]2-, [Mo2O2S8(SCH3)]-, and [Mo2O2S8Cl]- derivatives
Hadjikyriacou,Coucouvanis
, p. 2169 - 2177 (2008/10/08)
Investigation of the oxidative transformations of [MoOS8]2- has led to the characterization of the Mo(VI) oxo disulfido complexes [Mo2O2S9]2- and [Mo2O2S10]2- as a solid mixture in the structure of (Et4N)2[Mo2O2S9.14] (I). Oxidative coupling of I affords the Mo(VI) linear tetramer (Et4N)2[Mo4O4S18] (III). Reaction of either I or III with NiCl2 in MeCN generates the new chloro derivative (Et4N)[Mo2O2S8Cl] (IV) as a result of ligand exchange. The nucleophilicity of [Mo2O2S9]2- is demonstrated in its reaction with MeI, which gives the methanethiolato-bridged derivative (Et4N)[Mo2O2S8(SMe)] (II). Both I and II crystallize in the space group P21/c with four molecules per unit cell. The cell dimensions are a = 16.734 (2) ?, b = 10.407 (2) A7ring;, c = 17.457 (3) ?, and β = 97.06 (1)° for I and a = 13.866 (4) ?, b = 12.927 (4) ?, c = 14.219 (4) ?, and β = 118.80 (2)° for II. Compounds III and IV crystallize in space groups P1 and P21/n, respectively. The cell dimensions are a = 11.726 (3) ?, b = 12.851 (3) ?, c = 16.183 (4) ?, α = 79.21 (2)°, β = 82.68 (2)°, and γ = 79.65 (2)° for III and a = 13.309 (5) ?, b = 10.663 (3) ?, c = 16.360 (5) ?, and β = 113.74 (2)° for IV. Full-matrix refinement of 257 parameters on 3065 data for I, 208 parameters on 1803 data for II, 357 parameters on 5094 data for III, and 163 parameters on 1478 data for IV gave final Rw values of 0.064, 0.033, 0.052, and 0.037, respectively. The structures of I-IV contain Mo(VI) ions with pseudo-pentagonal-bipyramidal environments. One of the axial sites is occupied by a terminal oxo ligand. The second one is occupied by an intramolecularly weakly interacting sulfur. Two η2-S22- ligands and a bridging sulfur ligand define the equatorial plane of the pentagonal bipyramid. Adjacent bipyramids share the bridging ligand as common equatorial site: S2- in [Mo2O2S9]2-, η1,η1-S22- in [Mo2O2S10]2-, SMe- in [Mo2O2S8(SMe)]-, η2,η1-S22- in [Mo2O2S8Cl]-, and one η1,η1-S22- and two η2,η1-S22- ligands in [Mo4O4S18]2-. Selected bond lengths (?): in I, Mo-Mo = 3.606 (1), Mo=O = 1.676 (6); in II, Mo-Mo = 3.570 (1), Mo-SMe = 2.525 (2), Mo=O = 1.672 (6); in III, Mo-Mo = 3.606 (1) and 3.561 (1), Mo=O = 1.676 (8), Mo-η1,η1-S2 = 2.417 (3); in IV, Mo-Mo = 3.550 (1), Mo=O = 1.654, Mo-Cl = 2.388 (3). The spectroscopic properties as well as detailed synthetic procedures for I-IV are reported.
Physicochemical characterization of MFm--based ammonium ionic liquids
Li, Haifang,Zhao, Guoying,Liu, Fangfang,Zhang, Suojiang
, p. 1505 - 1515 (2013/07/26)
A series of ammonium-based ionic liquids (ILs), which share a homologous series of cations (CH3CH2)3N+(C nH2n+1) with n = 2, 4, 6, 8 and the anions with either BF4-, PF6-, or SbF6 -, was synthesized. Their structures were confirmed by 1H and 13C NMR, ESI-MS, and elemental analysis. Meanwhile, the content of impurity (e.g., water and bromide ions) was also determined using Karl Fischer titrator and ion chromatography. The thermal properties of the ILs were determined by TGA and DSC. Five of the investigated ILs have been shown to have a low melting point (2222]BF4, N,N,N,N-tetraethylammonium hexafluorophosphate, [N2222]PF6, N,N,N- triethylhexylammonium tetrafluoroborate, [N2226]BF4, N,N,N-triethyloctylammonium hexafluorophosphate, [N2228]PF 6 and N,N,N-triethyloctylammonium hexafluoroantimonate, [N 2228]SbF6. Densities, refractive indices, and miscibility of these 12 ILs were well studied systematically. Moreover, from the analysis of the structure-property relationship, the role of the alkyl chain length of the cation on these physical properties of the ILs has been assessed, and the influence of the nature of the anions on these experimental data of the ILs has been discussed. The studies may provide valuable contributions for the design and study of ILs.
Formation of Bridging Acylium and Nitrilium Complexes by Reaction of CO and CNC(CH3)3 with a Bridging Diiron Methylidyne Complex. Evidence for Strong Elelctron Donation from the Fe2C Core onto the μ-CHCO and μ-CHCNR Ligands
Casey, Charles P.,Crocker, Mark,Niccolai, Gerald P.,Fagan, Paul J.,Konings, Mark S.
, p. 6070 - 6076 (2007/10/02)
The reaction of the μ-methylidyne complex 2(μ-CO)(μ-CH)+PF6- (1) with CO gave the cationic 1:1 adduct 2(μ-CO)(μ-CHCO)+PF6- (2) in 90 percent yield.The structure, spectra, and chemical properties of 2 suggest that the bonding of the μ-CHCO ligand in 2 should be regarded as analogous to that in organic acylium cations, with a contributing formulation as a two-electron three-center bound-bridging ketene. 2 reacted with nucleophiles at the acylium carbon; reaction with Et4N+HFe(CO)4- gave the aldehyde 2(μ-CO)(μ-CHCHO) (3), water gave the carboxylic acid 2(μ-CO)(μ-CHCO2H) (4), and ammonia gave the amide 2(μ-CO)(μ-CHCONH2) (5). 1 also reacted with CNC(CH3)3 to give the 1:1 adduct 2(μ-CO)+PF6- (6), the structure of which was determined by X-ray crystallography; 6 crystallizes in the monoclinic space group P21/c, with unit cell constants a = 10.771 (2) Angstroem, b = 11.420 (2) Angstroem, c = 18.092 (3) Angstroem, β = 106.09 (1) degree, and Z = 4.The μ-ethylidyne complex 2(μ-CO)(μ-CCH3)+BF4- (7) underwent a similar reaction with CNC(CH3)3 to afford the adduct 2(μ-CO)+BF4- (8), which was isolated as a mixture of two cis and one trans Cp isomers.The structure of 6, together with the spectroscopic properties of 6 and 8, suggests an analogous bonding mode to that in 2.Fenske-Hall molecular orbital calculations performed on 2 and 6 provide further support for the importance of a ketene-like formulation that contributes to the overall structure of these complexes.
Die Reaktion von PF5*CH3CN mit Sulfid
Kolditz, Lothar,Calov, Ursula,Bechstein, Christiane
, p. 303 - 304 (2007/10/02)
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