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In this study, the first crystal structure of acetylenedicarbonyl fluoride is reported. Furthermore, the title compound was investigated in the superacidic media XF/SbF5 (X = H, D) which led to the formation of the monoprotonated species. Sur-prisingly, the diprotonated species was only formed by employing the monoprotonated species in 1,1,1,2-tetrafluoroethane whereas attempts at its synthesis in anhydrous hydrogen fluoride were unsuccessful. The vibrational spectroscopy is discussed together with quantum chemical calculations on the DFT/aug-cc-pVTZ level of theory. The stability of the Z-conformation of protonated acyl fluorides is calculated on the MP2/aug-cc-pVTZ level of theory. [ABSTRACT FROM AUTHOR]

The reactions of oxalyl chloride were investigated in the binary superacidic systems HF/SbF5 and DF/SbF5. O‐Monoprotonated oxalyl chloride was isolated and represents the first example of a protonated acyl chloride. Diprotonated oxalyl chloride is only stable in solution. Salts of the ClCO+ cation were synthesized from the reactions of oxalyl chloride or COClF with SbF5 in 1,1,1,2‐tetrafluoroethane (R‐134a, CF3CFH2). The colourless salts were characterized by low‐temperature vibrational spectroscopy, NMR spectroscopy and single‐crystal X‐ray diffraction. (1,2‐Dichloro‐2‐oxoethylidene)oxidanium hexafluoridoantimonate(V), [C2O(OH)Cl2][SbF6], crystallizes in the monoclinic space group P21 and carbonyl chloride hexadecafluoridotriarsenate(V) [ClCO][Sb3F16], in the trigonal space group P31, with two and three formula units per unit cell, respectively. Monoprotonated oxalyl chloride and the ClCO+ cation both display very short C—Cl bonds with a strong double‐bond character. [ABSTRACT FROM AUTHOR]

Taurine is part of the cysteine cycle and is one of the few naturally occuring organosulfur‐based molecules in the human body. As implied by modern studies, protonated taurine is of biological impact. The first attempts to isolate its protonated species in the binary superacidic system HF/SbF5 were performed by Hopfinger, resulting in the isolation of monoprotonated taurine. Since the chosen conditions seemed rather harsh, investigations in less acidic systems were performed at room temperature to explore the involved protonated species. Herein, we present the structure of 2‐[dihydroxy(oxo)sulfanyliumyl]ethanaminium bis[hexafluoridoarsenate(V)], [H2O3SC2H4NH3][AsF6]2, the diprotonated form of 2‐aminoethanesulfonic acid (taurine). It was synthesized in the binary superacidic system HF/AsF5 and crystallizes as colourless needles. Diprotonated taurine was structurally characterized by single‐crystal X‐ray diffraction analysis, low‐temperature vibrational spectroscopy and NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Propiolamide and cellocidin were investigated in superacidic media. In both acetylenic amides, the amide moiety is immediately monoprotonated in anhydrous HF, HF/SbF5 and HF/BF3. An increase of SbF5 does not lead to a more highly protonated species. The salts were characterized by low-temperature Raman, NMR and room temperature IR spectroscopy, as well as by single-crystal X-ray diffraction. The experimental data are discussed together with results of quantum-chemical calculations on the M06-2X/aug-cc-pVTZ level of theory, which are consistent with the observation of pure monoprotonation. The second protonation of the amide moiety or the triple bond is not observed due to the high positive charge caused by the monoprotonation. [ABSTRACT FROM AUTHOR]

Abstract Salts containing the monoprotonated ethylene carbonate species of were obtained by reacting it with the superacidic systems XF/MF5 (X=H, D; M=Sb, As). The salts in terms of [C3H5O3]+[SbF6]−, [C3H5O3]+[AsF6]− and [C3H4DO3]+[AsF6]− were characterized by low‐temperature infrared and Raman spectroscopy. In order to generate the diprotonated species of ethylene carbonate, an excess of Lewis acid was used. However, this only led to the formation of [C3H5O3]+[Sb2F11]−, which was characterized by a single‐crystal X‐ray structure analysis. Quantum chemical calculations on the B3LYP/aug‐cc‐PVTZ level of theory were carried out for the [C3H5O3]+ cation and the results were compared with the experimental data. A Natural Bond Orbital (NBO) analysis revealed sp2 hybridization of each atom belonging to the CO3 moiety, thus containing a remarkably delocalized 6π‐electron system. The delocalization is confirmed by a 13C NMR‐spectroscopic study of [C3H5O3]+[SbF6]−.

Methylfluoride and hydrogen fluoride react with powerful methylating agent [SO2Me]+ in a temperature-dependent addition reaction to form methylated fluorosulfuric acid [FS(OMe)2][Sb2F11] and methylated fluorosulfuric acid methyl ester [FS(OH)(OMe)][SbF6], respectively. The obtained methylated fluorosulfinic acid and methylated fluorosulfinic acid methyl ester were characterized by single X-ray structure analysis and vibrational spectroscopy. [ABSTRACT FROM AUTHOR]

The reactions of difluoroacetyl fluoride and trifluoroacetyl fluoride were investigated in the binary superacid HF/SbF5 by low-temperature NMR spectroscopy. Whereas both haloacetyl fluorides form oxonium species after the addition of HF, the protonated acyl fluorides were not observed. Protonated 1,1,2,2-tetrafluoroethanol was isolated as a solid and represents an example of a protonated α-fluoroalcohol. The salt was characterized by low-temperature vibrational spectroscopy and single-crystal X-ray diffraction. [CHF2CF2OH2][SbF6] crystallizes in the triclinic space group P1¯ with two formula units per unit cell. Protonated perfluoroethanol is only stable in solution. The reactivity of both haloacyl fluorides is discussed based on quantum chemical calculations at the MP2/aug-cc-pVTZ-level of theory. [ABSTRACT FROM AUTHOR]

The structure of cis‐ or trans‐bridged [GeF5]− anionic chains have been investigated [Mallouk et al. (1984). Inorg. Chem.23, 3160–3166] showing the first crystal structures of μ‐F‐bridged pentafluorogermanates. Herein, we report the second crystal structure of trans‐pentafluorogermanate anions present in the crystal structure of sodium trans‐pentafluorogermanate(IV) bis(hydrogen fluoride), Na[GeF5]·2HF. The crystal structure [orthorhombic Pca21, a = 12.3786 (3), b = 7.2189 (2), c = 11.4969 (3) Å and Z = 8] is built up from infinite chains of trans‐linked [GeF6]2− octahedra, extending along the b axis and spanning a network of pentagonal bipyramidal distorted Na‐centred polyhedra. These [NaF7] polyhedra are linked in a trans‐edge fashion via hydrogen fluoride molecules, in analogy to already known sodium hydrogen fluorides and potassium hydrogen fluorides. [ABSTRACT FROM AUTHOR]

The acid‐activation of 1,2‐dicarbonyl compounds plays a key role in a variety of electrophilic reactions, some of which are only accessible in superacidic media when a superelectrophilic dication is formed. To obtain structural and electronic information about these elusive species, the vicinal dication [C2(OH)2Me2]2+ is synthesized and characterized by Raman spectroscopy and X‐ray diffraction. Since this superelectrophile could not be stabilized in convenient superacids, the usage of liquid SO2 turned out to be crucial. The experimental data are discussed together with quantum‐chemical calculations on the B3LYP/aug‐cc‐pVTZ level of theory. Natural Bond Orbital (NBO) analyses quantify the superelectrophilic interactions found in the solid state. [ABSTRACT FROM AUTHOR]

The salt ammonium 2‐aminomalonate (systematic name: ammonium 2‐azaniumylpropanedioate), NH4+·C3H4NO4−, was synthesized in diethyl ether from the starting materials malonic acid, ammonia and bromine. The salt was recrystallized from water as colourless blocks. In the solid state, intramolecular medium–strong N—H...O, weak C—H...O and weak C—H...N hydrogen bonds build a three‐dimensional network. [ABSTRACT FROM AUTHOR]

Abstract Protonation of 1,3,5‐tricyano‐ and 1,3,5‐triaminobenzene was achieved in various superacidic media, resulting in the formation of the respective trinitrilium and triammonium species. Furthermore, the respective N‐methyl nitrilium species was synthesized by methylation. Characterization was performed by NMR and vibrational spectroscopy, followed by single‐crystal X‐ray diffraction analyses of selected species. Fourfold protonation of the amine, which would have led to the triammonium arenium species, could not be achieved. Quantum chemical calculations are employed to enable full vibrational assignment as well to quantify charge localization.

Abstract The refrigerant trans‐1,3,3,3‐tetrafluoropropene (HFO‐1234ze) is used as a replacement for former cooling agents that have been phased‐out due to their global warming potential or ozone depleting potential. Although it is used on a large scale, only a few vibrational data and no structural data of HFO‐1234ze are known. We report structure determinations based on low‐temperature single‐crystal X‐ray diffraction data as well as gas‐phase diffraction data of HFO‐1234ze and HFO‐1234yf (2,3,3,3‐tetrafluoropropene). Furthermore, vibrational spectra of HFO‐1234ze in all phases are described. The results are discussed together with quantum‐chemical calculations on the PBE0/cc‐pVTZ level of theory. Combustion experiments of HFO‐1234ze show carbonyl difluoride, carbon dioxide and hydrogen fluoride to be the main combustion products.

The accumulation of chiral ammonium‐oxocarbenium dications in superacid is evidenced by low‐temperature NMR spectroscopy, X‐ray diffraction analysis and confirmed by DFT calculations. Its potential for the diastereoselective remote hydrofunctionalization of non‐activated alkene is also explored. [ABSTRACT FROM AUTHOR]

Salts of protonated sulfur dioxide were synthesized by recrystallization of [FS(OX)2][SbF6] (X=H, D) in aprotic solvents at low temperatures. Hemiprotonated sulfur dioxide [(SO2)2H][Sb2F11] was obtained from the solvent SO2 and the monoprotonated sulfur dioxide [OSOD][Sb2F11], using 1,1,1,2‐tetrafluoroethane as solvent. For both compounds, single crystals were obtained and an X‐ray structure analysis was conducted. Furthermore, the salts were characterized by Raman spectroscopy and the results were discussed together with quantum chemical calculations on the M06‐2X/aug‐cc‐pVTZ level of theory. [ABSTRACT FROM AUTHOR]