ABSTRACT
Sulfurtrioxide reacts with the superacidic solutions XF/SbF(5) (X=H, D) to form the corresponding salts [X(2)SO(3)F](+)[SbF(6)](-), which are the protonated forms of fluorosulfuric acid. The salts have been characterized by vibrational spectroscopy and a single-crystal structure analysis. [H(2)SO(3)F](+)[SbF(6)](-) crystallizes in the monoclinic space group P2(1)/n (no. 14) with four formula units in the unit cell. The crystal structure possesses a distorted tetrahedral O(3)SF skeleton of the cations, which are linked with two strong hydrogen bridges to [SbF(6)](-) anions and forms a one-dimensional chain. The crystal structure and the vibrational spectra are compared to the quantum-chemical-calculated free [H(2)SO(3)F](+) cation. Additionally, an [H(2)SO(3)F(HF)(2)](+) unit was calculated at the RHF/6-311(++)G(d,p) level to simulate HF hydrogen bridges found in the solid state.
ABSTRACT
The gas phase structure of O-nitrobis(trifluoromethyl)hydroxylamine, (CF(3))(2)NONO(2), has been determined with gas electron diffraction and quantum chemical calculations (HF, MP2, and B3LYP with 6-31G basis sets). The calculations predict a structure with C(s) overall symmetry, a planar NONO(2) skeleton, and the NO(2) group oriented anti with respect to the CNC plane. The electron diffraction intensities are reproduced very well with such a model. The molecule possesses pyramidal configuration at the amino nitrogen atom, and the following geometric parameters (r(a) values with 3sigma uncertainties) were obtained for the NONO(2) skeleton: N-O = 1.392(18) A, O-N = 1.597(16) A, (N=O)(mean) = 1.192(4) A, N-O-N = 106.9(25) degrees, O=N=O = 138.4(24) degrees. The extremely long O-N distance is rationalized by very weak bonding between the two stable radicals (CF(3))(2)NO and NO(2). Whereas the ab initio methods HF (O-N = 1.395 A) and MP2 (O-N = 1.664 A) fail to reproduce this bond length correctly, the hybrid method B3LYP (O-N = 1.584 A) results in good agreement.
ABSTRACT
The reaction of tribromophosphine oxide in the superacidic systems XF/MF(5) (X = H, D; M = As, Sb) leads to tribromohydroxyphosphonium hexafluorometalates. The structure was successfully elucidated in the case of tribromohydroxyphosphonium hexafluoroarsenate. Br(3)POH(+)AsF(6)(-) crystallizes in the orthorhombic space group Pnma (No. 53 with a = 1292.5(1) pm, b = 871.6(1) pm, and c = 845.0(1) pm) with four formula units per cell. The Raman, IR, (1)H NMR, and (31)P NMR spectra of Br(3)POX(+)MF(6)(-) (X = H, D; M = As, Sb) are reported.
ABSTRACT
We have studied the preparation and isolation of the halogenated alkylidene oxonium salts CH(3)OCHX(+)MF(6)(-) (X = Cl, F; M = As, Sb). Addition of dichloromethylmethylether at -78 degrees C to the superacidic media HF/MF(5) resulted in the formation of the chlorine compounds CH(3)OCHCl(+)MF(6)(-), whereas at -65 degrees C the fluorinated salts CH(3)OCHF(+)MF(6)(-) are formed by a chlorine/fluorine exchange. The salts are characterized by their low-temperature IR and Raman spectra. Additionally, the crystal structures of the hexafluoroantimonates are presented. The structures of the cations turned out to be different in some points. The salt CH(3)OCHF(+)SbF(6)(-) crystallizes in the monoclinic space group P2(1)/c with 4 molecules in the unit cell and a = 9.942(2), b = 7.454(2), and c = 10.297(3) Å; beta = 111.27(2) degrees. The salt CH(3)OCHCl(+)SbF(6)(-) crystallizes in the monoclinic space group P2(1)/c with 4 formula in the unit cell and a = 5.970(3), b = 12.019(5), and c = 10.994(5) Å; beta = 92.59(3) degrees.
ABSTRACT
(Trifluoromethyl)iodine dichloride (CF(3)ICl(2)) is synthesized by the reaction of (trifluoromethyl)iodine chloride fluoride (CF(3)I(Cl)F) with trimethylchlorosilane ((CH(3))(3)SiCl) at -40 degrees C. By using this route of preparation, in which CF(3)I(Cl)F undergoes a chlorine-fluorine exchange, CF(3)ICl(2) can be obtained in high purity and yield. CF(3)ICl(2) crystallizes in the orthorhombic space group Cmca with a = 6.990(1) Å, b = 7.985(1) Å, c = 21.177(1) Å, and eight formula units per unit cell. The final R indices [I > 2sigma(I)] are R(1) = 0.0341 and wR(2) = 0.0631. CF(3)ICl(2) is, in contrast to iodine trichloride (ICl(3)), monomeric, and its molecular structure is T-shaped with the CF(3) group in the equatorial position. The Raman, IR, and NMR spectra are also described.
ABSTRACT
Dimethyltrithiocarbonate reacts with the superacidic systems HF/MF(5) and DF/MF(5) (M = As, Sb) to form (MeS)(2)CSX(+)MF(6)(-) (X = H, D). With an excess of AsF(5) the reaction leads to (MeS)(2)CSX(+)As(2)F(11)(-) (X = H, D). The latter salt crystallizes in the monoclinic space group P2(1)/c (No. 14 with a = 7.687(1) Å, b = 21.327(6) Å, c = 8.704(1) Å, and beta = 91.99(1) degrees ) with four formula units per cell. The undecafluorodiarsenate anion contains an As-F-As bridge with two As-F bonds significantly longer than the nonbridging bonds and an As-F-As angle of 159.1(6) degrees. The Raman, IR, and (1)H, (75)As, (19)F, and (13)C NMR spectra of (MeS)(2)CSX(+)SbF(6)(-) and (MeS)(2)CSX(+)As(2)F(11)(-) (X = H, D) are reported.
ABSTRACT
Stabilization by salt formation: carbonic acid, which is not available as a pure substance, was isolated in the form of its trihydroxycarbenium salts, C(OH)3+ MF6- (M=As, Sb), from the reaction of carbonic acid bis(trimethylsilyl) ester in the superacids HF/MF5 . The structure of the cation is shown in the picture. The ion was also characterized by vibrational spectroscopic studies.
ABSTRACT
Phosphorous acid reacts with the superacidic system HF/SbF(5) with formation of HPF(4), water, and oxonium hexafluoroantimonate, which crystallizes as H(5)O(2)(+)SbF(6)(-) in the triclinic space group P&onemacr; with a = 6.492(6) Å, b = 7.469(8) Å, c = 8.095(6) Å, alpha = 116.17(7) degrees, beta = 93.90(7) degrees, and gamma = 112.34(7) degrees, with two formula units per unit cell. The unit cell contains two H(5)O(2)(+) ions of approximate symmetry C(2)(h)() with an intramolecular O.O distance of 2.418(8) or 2.40(1) Å, respectively. The reaction is discussed with regard to the formation of protonated species in various superacidic media. In addition the crystal structure of Me(4)N(+)HPF(5)(-) which is formed by the reaction of HPF(4) with Me(4)N(+)F(-) is reported. The salt crystallizes in the tetragonal space group P4/nmm with a = 8.564(5) Å and c = 5.687(2) Å, with two formula units per unit cell. The P-F distances of P-F(eq) = 1.595(6) Å and P-F(ax) = 1.594(9) Å for the psi-octahedral HPF(5)(-) show no significant interaction exercised by hydrogen on the cis- and trans-fluorine.
ABSTRACT
Protonated hydrogen peroxide is produced from the reaction of antimony pentafluoride with bis(trimethylsilyl)peroxide in the presence of hydrogen fluoride. Depending on the stoichiometry of the reaction mixture, the compounds H3 O2 SbF6 and H5 O4 SbF6 are formed, which are stable up to room temperature and have been characterized by X-ray crystallography. The structure of the H3 O2+ ion is shown on the right.
ABSTRACT
An oxonium ion with hydroxymethyl and methylidene substituents is found in the salts 1-MF6 (M=As, Sb), which can be isolated from solutions of formaldehyde in superacids HF/MF5 . Their formation was at first surprising, since NMR spectroscopy indicates that protonated monofluoromethanol is present in solution.
ABSTRACT
The synthesis and isolation of the hypobromite CF(3)OBr is reported. CF(3)OBr is formed besides Me(4)N(+)BrF(2)(-) by the reaction of CF(3)OCl and Me(4)N(+)Br(3)(-) via an addition-elimination mechanism. The initially formed solid, [2CF(3)OBr.Me(4)N(+)BrF(2)(-)], was characterized by (13)C and (19)F NMR, Raman, IR, and mass spectra. The hypobromite was separated from the solid by high-vacuum condensation onto a cold surface and characterized by matrix isolation multichannel Raman spectroscopy. An ab initio calculation was performed, and a force field and the torsional barrier of CF(3)OBr were calculated. The calculation predicts an eclipsed conformation with a rotional barrier of 3.4 kcal/mol. The photolytic decomposition of CF(3)OBr in the solid state and in an argon matrix was investigated.
