Oxalic acid forms in superacidic solutions HF/MF5 (M = As, Sb) its corresponding mono‐ and diprotonated salts [HOOCC(OH)2][MF6] and [(HO)2CC(OH)2][MF6]2 (M = As, Sb). The number of protonations is strongly dependent on the stoichiometric ratio of the Lewis acid with regard to oxalic acid. Mono‐ and diprotonated salts were characterized by vibrational spectroscopy and in the case of [HOOCC(OH)2][AsF6] (1) and [(HO)2CC(OH)2][SbF6]2 (4) by a single‐crystal X‐ray structure analysis. The salts crystallize in the monoclinic space groups P21/c and P21/n with eight, respectively four, formula units per unit cell. The vibrational spectra were compared to quantum chemical calculations of the cations [HOOCC(OH)2]+ and [(OH)2CC(OH)2]2+⋅4HF. In addition to this, an MEP analysis together with the NPA charges of [(OH)2CC(OH)2]2+, [(OH)2CC(OH)2]2+⋅6HF and oxalic acid were calculated to locate the positive charge. The protonation of oxalic acid does not lead to a remarkable change of the C‐C bond length, which is discussed for the entire series of the oxalic skeleton, starting with the dianion and ending with the tetrahydroxy dication.
The syntheses of alkali and earth alkaline dinitropyrazolate (DNP), trinitropyrazolate (TNP), and trinitroimidazolate (TNI) salts are reported. Additionally, copper trinitroimidazolate was synthesized. Their characterization by NMR spectroscopy, mass spectrometry, elemental analysis, and vibrational spectroscopy is reported as well. Crystal structures of compound Ba(DNP) 2 (9), which crystallizes with one molecule of methanol and ethyl ether as well as of compounds Sr(TNP) 2 ·3H 2 O (12), Ba(TNP) 2 ·3H 2 O (13), and LiTNI·3H 2 O (14) were determined. The energetic and thermal properties were measured * Prof. Dr. T. M. Klapötke
Croconic acid reacts in superacidic solutions HF/MF5 (M = As, Sb) to yield its corresponding salts [H3O5C5][MF6] and [(H3O5C5)H(H3O5C5)][MF6]3·2HF (M = As, Sb). The degree of protonation is strongly dependent on the stoichiometric ratio of the Lewis acid regarding croconic acid. Monoprotonated salts were characterized by vibrational spectroscopy and in the case of [H3O5C5][AsF6] (1) by a single‐crystal X‐ray structure analysis. [H3O5C5][AsF6] crystallizes in the monoclinic space group P21/c with four formula units per unit cell. The sesquiprotonated species of croconic acid [(H3O5C5)H(H3O5C5)][SbF6]3·2HF (4) was also characterized by single‐crystal X‐ray structure analysis. It crystallizes in the triclinic space group P1 with one formula unit per unit cell. The vibrational spectra of the monoprotonated salts were compared to quantum chemical calculations of the [H3O5C5]+·3HF cation and experimental data reported for croconic acid.
Guanidinium chloride reacts with the superacidic solutions HF/MF (M=As, Sb) at a molar ratio of 1:2 under formation of the diprotonated guanidinium salts [C(NH ) (NH )][AsF ] and [C(NH ) (NH )][SbF ] . The compounds were characterized by using infrared and Raman spectroscopy. Furthermore, single-crystal X-ray structure analysis of the guanidinium(2+) salts [C(NH ) (NH )][SbF ] ⋅HF, [C(NH ) (NH )] [Ge F ]⋅HF, and [C(NH ) (NH )] [Ge F ]⋅2 HF and the guanidinium(1+) salt [C(NH ) ][SbF ] is reported. The discussion of the experimental data is supported by quantum-chemical calculations of the [C(NH ) (NH )] and [C(NH ) ] ions to investigate the modification of the resonance stabilization during the protonation process at the PBE1PBE/6-311G++(3df,3pd) level of theory. The planar CN skeleton of the guanidinium(2+) ion has two carbon-nitrogen bonds in the range 1.286(4)-1.293(4) Å and one carbon-nitrogen bond of 1.453(4) Å, which can be explained with a decreased resonance stabilization relative to the guanidinium(1+) ion.
Abstract. Malononitrile reacts in superacidic solutions HF/MF 5 (M = As, Sb) with formation of the corresponding salts [H 2 C(CNX) 2 ][MF 6 ] 2 (M = As, Sb; X = H, D). The occurrence of double protonation is strongly dependent on the stoichiometric ratio of the Lewis acid with regard to malononitrile. Deuterated species were obtained by replacing hydrogen fluoride with deuterium fluoride. The double protonated salts
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