Synthesis and Structural Investigation of Protonated Haloacetyl Fluorides

Herein, we report the O-monoprotonated species of chloroacetyl fluoride and fluoroacetyl fluoride in the binary superacidic systems HF/MF5 and DF/MF5 (M=As, Sb) as hexafluoridoarsenates and hexafluoridostibates. The colorless salts were characterized by low temperature vibrational spectroscopy, low temperature NMR spectroscopy and single-crystal X-ray diffraction. [CCIH2C(OH)F][SbF6] crystallizes in the monoclinic space group P2(1)/c with four formula units per unit cell and [CIH2FC-(OD)F][SbF6] in the triclinic space group P (1) over bar with two formula units per cell. The experimental data are discussed together with quantum chemical calculations at the omega B97XD/aug-cc-pVTZ-level of theory. Protonation leads to significant shortening of the C F bond due to back-donation of fluorine lone-pair electrons

Third Time is a Charm - Protonating Tricarboxybenzenes

Triprotonation of the three constitution isomers of tricarboxybenzene was accomplished. Furthermore, the preparation of selected mono- and dications showed the sequence of protonation steps. The cations were mostly isolated as [SbF6] and [AsF6] species, which were characterized by Raman and NMR spectroscopy as well as X-ray structure determination. To further elucidate the experimental results, quantum chemical calculations are employed, especially in regard to charge distribution with NPA charges and aromaticity by NICS(0) values. Thermal decomposition of the compounds was investigated in order to explore the possibility of acyl cation formation. The influence of the aromatic system, substitution pattern and anomeric effect concerning the properties of the respective compounds was thus explained

Intermediates in Friedel-Crafts Acylation of Fumaryl Halides

Fumaryl chloride and fluoride were reacted with different Lewis acids to synthesize the intermediates of the Friedel-Crafts acylation. The salt of the monoacyl cation [C4H2FO2](+)[Sb3F16](-) was obtained from the reaction of fumaryl fluoride with SbF5 in SO2ClF solutions. The reaction was repeated using fumaryl chloride as starting material, which reacted under halogen exchange to obtain the salt of the monoacyl cation [C4H2FO2](+)[SbCl2F4](-). In addition, the reaction of fumaryl chloride with SbCl5 in SO2ClF was studied. The covalent donor-acceptor complex C4H2Cl2O2 center dot 2 SbCl5 was formed, containing oxygen-bonded Lewis acids. The compounds were characterized by low-temperature vibrational spectroscopy. Single-crystal X-ray structure analyses were conducted for [C4H2FO2](+)[Sb3F16](-) as well as for C4H2Cl2O2 center dot 2 SbCl5. In the solid state of [C4H2FO2](+)[Sb3F16](-) C center dot center dot center dot O and C center dot center dot center dot F contacts are observed and the origin of these interactions is discussed by means of ESP maps and NBO analysis. The monoacyl cation is stabilized by electrostatic attraction and electron back-donation from oxygen and fluorine ligands to the positive ring-structured pi-hole at the oxocarbenium center. Besides, the formation of the diacyl cation is not observed, which is based on small distances between the positive charges involving charge-charge repulsion. The great advantage of using fumaryl halides in Friedel-Crafts acylation is featured by the possibility to synthesize ketones keeping an acyl fluoride moiety

Protonation of Pyruvic Acid - Synthesis of a plain Superelectrophile

The syntheses of [H3C(O)CC(OH)(2)][MF6] and [H3C(OH)CC-(OH)(2)][MF6](2) (M=As, Sb) by reacting pyruvic acid in the superacidic systems HF/AsF, and HF/SbF5 are reported. The salts were characterized by low-temperature vibrational spectroscopy and in the cases of [H3C(O)CC(OH)(2)][SbF6] and [H3C(OH)CC-(OH)(2)][SbF6](2)center dot HF by X-ray crystal structure analyses. The exper- imental results are discussed together with quantum chemical calculations. Remarkably, the bond distance and the twisting angle around the central C-C bond are unaffected by the protonations despite increasing coulombic repulsion. The crystal structure reveals short interionic interactions that have a considerable influence on the C-C bond

Stabilizing the C-N Double Bond Character in Fumaramide with the Aid of Superacids

Fumaramide was reacted with the superacidic systems XF/SbF5 and XF/BF3 (X = H, D) leading to the formation of the 0-diprotonated species. Using an equimolar amount of the Lewis acids relating to fumaramide, a mixture of the diprotonated salt and the diadduct with O-coordinated HF was obtained. The salts [C4H2X6N2O2](2+)[(BF4)(-)](2) and [C4H2X6N2O2](2)center dot[(SbF6)(-)](2) (X = H, D) were characterized by low-temperature vibrational spectro-scopy. Single-crystal X-ray structure analyses were carried out for the compounds [C4H8N2O2](2+)[(BF4)(-)](2), C4H6N2O2 center dot center dot center dot 2HF, and fumaramide. To discuss the experimental results, quantum chemical calculations were executed at the B3LYP/aug-cc-pVTZ level of theory. To investigate the impact of the protonation on the resonance + M effect and the electron distribution concern- ing the conjugated system ESP maps, NPA charges, and NBO analyses were consulted. Due to the protonation, the nitrogen lone pair contributes completely to the formation of the C=N pi-bond, stabilizing the C=N double bond character. Since no monoprotonation of fumaramide is observed, amide hydrolysis is possible simultaneously on both amide groups

Strengthening of the C-F Bond in Fumaryl Fluoride with Superacids

The reaction of fumaryl fluoride with the superacidic solutions XF/MF5 (X=H, D;M=As, Sb) results in the formation of the monoprotonated and diprotonated species, dependent on the stoichiometric ratio of the Lewis acid to fumaryl fluoride. The salts [C4H3F2O2](+)[MF6](-) (M=As, Sb) and [C4H2X2F2O2](2+)([MF6](-))(2) (X=H, D;M=As, Sb) are the first examples with a protonated acyl fluoride moiety. They were characterized by low-temperature vibrational spectroscopy. Low-temperature NMR spectroscopy and single-crystal X-ray structure analyses were carried out for [C4H3F2O2](+)[SbF6](-) as well as for [C4H4F2O2](2+)([MF6](-))(2) (M=As, Sb). The experimental results are discussed together with quantum chemical calculations of the cations [C4H4F2O2 . 2 HF](2+) and [C4H3F2O2 . HF](+) at the B3LYP/aug-cc-pVTZ level of theory. In addition, electrostatic potential (ESP) maps combined with natural population analysis (NPA) charges were calculated in order to investigate the electron distribution and the charge-related properties of the diprotonated species. The C-F bond lengths in the protonated dication are considerably reduced on account of the +R effect

Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure

[EN] A series of alkyltributylphosphonium chloride ionic liquids, prepared from tributylphosphine and the respective 1-chloroalkane, CnH2n+1Cl (where n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12 or 14), is reported. This work is a continuation of an extended series of tetraalkylphosphonium ionic liquids, where the focus is on the variability of n and its impact on the physical properties, such as melting points/glass transitions, thermal stability, density and viscosity. Experimental density and viscosity data were interpreted using QPSR and group contribution methods and the crystal structure of propyl(tributyl) phosphonium chloride is detailed.This work was funded by Cytec Canada, Inc. G.A. would like to thank Dr Douglas Harris (Cytec) for fruitful comments and advice at the beginning of this work; Prof. Chris Strauss, Dr Markus Fanselow and Dr Giulia Fiorani for microwave assistance and helpful guidance, and Prof. P.R. Raithby for the X-ray diffraction data collection. L.P.N.R. thanks Fundacao para a Ciencia e Tecnologia, Portugal, for support under grants PTDC/QUI-QUI/101794/2008 and PTDC/QUI/71331/2006.Adamova, G.; Gardas, RL.; Nieuwenhuyzen, M.; Vaca Puga, A.; Rebelo, LPN.; Robertson, AJ.; Seddon, KR. (2012). Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure. Dalton Transactions. 41(27):8316-8332. doi:10.1039/c1dt10466gS83168332412