Edgardo H. Cutin

Spectroscopic and theoretical studies of sulfamoil fluoride, FSO2NH2 and N-(fluorosulfonyl) imidosulfuryl fluoride, FSO2NS(O)F2

Abstract FT-IR and Raman spectra of sulfamoil fluoride, FSO 2 NH 2 , and N-(fluorosulfonyl) imidosulfuryl fluoride, FSO 2 NS(O)F 2 , were obtained. The experimental data are compared to results of ab initio and density functional theory (DFT) calculations. According to the theoretical studies the main conformer of FSO 2 NH 2 possesses anti conformation (F–S single bond in anti position with respect to the nitrogen lone pair). The vibrational spectra do not confirm the presence of a second conformer in the gas and liquid phases. They have been interpreted on the basis of C S symmetry. The Raman spectra of the liquid and the gas infrared spectra of FSO 2 NS(O)F 2 have been interpreted in the terms of the existence of a single conformation possessing C 1 symmetry, as determined previously by gas electron diffraction (GED). An assignment of the observed bands is proposed for both molecules.

Structures and conformational properties of trifluoromethylsulfonyl isocyanate, CF3SO2NCO, and trifluoromethylsulfonyl azide, CF3SO2N3

Abstract The geometric structures of trifluoromethylsulfonyl isocyanate, CF 3 SO 2 NCO, and trifluoromethylsulfonyl azide, CF 3 SO 2 N 3 , have been determined by gas electron diffraction and by theoretical methods ( HF 6–31 G ∗ , HF 6–31 G ∗ , MP 2 6–31 G ∗ , B 3 P 91 6–31 G ∗ . Both compounds possess a single conformation with eclipsed or nearly eclipsed orientation of the NCO or N 3 group relative to one SO double bond and dihedral angles o (OSNC) = 4(8)° and o (OSNN) = − 24(6)°. The negative sign indicates that the azide group is rotated towards the CF 3 group. The SN bonds in both compounds are very similar (1.653(5) and 1.668(4) A, respectively). The nitrogen bond angle in the isocyanate (SNC = 126.5(15)°) is larger by 15° than that in the azide (SNN = 111.6(15)°). All theoretical methods reproduce the experimental structures satisfactorily except for the SC and SN bond lengths.

VIBRATIONAL STUDIES OF FLUOROFORMYLIMINOSULFUR DIFLUORIDE : FC(O)NSF2

Abstract The Raman spectrum of liquid fluoroformyliminosulfur difluoride. FC(O)NSF2, and its IR spectrum of the vapor phase were obtained. The observed features and the polarized Raman spectra are consistent with the existence of only one conformer possessing Cs symmetry both in the vapor and liquid phases. Assignment of 13 of the 15 fundamental vibrations are reported. The UV-visible spectrum was recorded and its bands assigned. The preresonance Raman effect was not detected. A theoretical ab initio vibrational spectrum was also obtained using a 6-31G∗ basis set. Symmetry force constants arising from experimental data were determined for the A′ species.

Conformational and bond properties of chlorosulfonyl isocyanate, CISO2NCO

Abstract The Raman and IR spectra of chlorosulfonyl isocyanate in the liquid phase are reinvestigated, and the IR spectra of the vapour phase are recorded. A complete assignment of the observed bands is proposed. Subsequently a normal coordinate analysis is performed. Vibrational data confirm that CISO 2 NCO exists only in one single conformation in both phases. The presence of depolarized bands in the Raman spectra of the liquid phase is consistent with either C 1 symmetry and a very low rotational barrier between the two equivalent optic isomers or with a C S symmetry. This interpretation allows the rationalization of data obtained from several spectroscopic techniques. An unusual force constant-bond length relationship is found for the S-Cl moiety.

Structure and conformation of fluoroformyliminosulfur difluoride, FC(O)NSF2

Abstract The conformational properties and the geometric structure of fluoroformyliminosulfur difluoride, FC(O)NSF 2 , were studied in the gas phase by vibrational spectroscopy and by joint analysis of gas electron diffraction (GED) intensities and rotational constants from the literature. Only one planar cis-syn conformation, with the FC(O) group cis to the SF 2 group and the CO double bond syn to the NS double bond, is observed. The contribution of any other conformer is estimated to be ⩽ 3%. The following skeletal geometric parameters ( r z values, estimated uncertainties are 2σ values) were derived: S  N = 1.479 (4) A , N  C = 1.395 (6) A , S  F = 1.586 (2) A , CNS = 126.7 (11)°, NSF = 110.4 (8)°, FSF = 93.4 (3)°. These geometric parameters are well reproduced by HF/6-31G∗ ab initio calculations.

Vibrational spectra and theoretical calculations of N-(trifluoromethyl)iminosulphur dichloride: CF3NSCl2

Abstract The Raman spectrum of liquid N -(trifluoromethyl)iminosulphur dichloride, CF 3 NSCl 2 and the infrared spectrum of its vapour phase were recorded. The observed features were consistent with the existence of only one conformer with Cs symmetry, as derived by the reported electron-diffraction analysis. Theoretical vibrational spectra were also determined using ab initio and Density Functional Theory (DFT) calculations at different levels of approximation. For all except one of the torsional modes, experimental wavenumbers were obtained. A subsequent normal coordinate analysis was performed using a torsional wavenumber calculated by theoretical methods.

Vibrational studies of sulfamoil chloride (ClSO2NH2)

Abstract The infrared spectrum of sulfamoil chloride in the liquid phase was reinvestigated; the infrared and Raman spectra of the solid phase have also been obtained. A complete assignment of the observed bands is proposed. A subsequent normal coordinate analysis was performed. The experimental data are compared to results of ab initio and DFT (density functional theory) calculations. According to the experimental and theoretical results the main conformer of ClSO2NH2 possesses an anti conformation (Cs symmetry, SCl single bond in anti position with respect to the nitrogen lone pair).

Vibrational Spectra of Trifluoromethanesulfonyl Isocyanate, CF3SO2NCO

CF3SO2NCO was prepared by reaction of ClSO2NCO and CF3SO2NH2. Fourier transform IR data for the vapour and Raman spectra for the liquid were obtained and compared with those of other isocyanates. Vibrational assignments were made for all but one of the torsional fundamental modes. The observed features and the polarization measurements of the Raman lines in the spectra of the liquid are consistent with the existence of only one conformer possessing C1 symmetry, in both the gas and liquid phases.

Vibrational spectra, assignments and ab initio calculations of sulfur difluoride chlorosulfonyl imide (ClSO2NSF2)

Abstract The gas FTIR (4000-400 cm−1) and the liquid Raman spectra (2000-50 cm−1) of sulfur difluoride chlorosulfonyl imide have been recorded. Assignment of 16 of the 18 fundamental vibrational modes were performed based on group frequencies and normal coordinate analysis. The fundamental vibrational frequencies are compared with those obtained from ab initio calculation employing the HF/6-31G∗ basis set and the corresponding values observed from related molecules. According to the computational approaches HF/3-21G∗, HF/3-31G∗ and BPW/916-31G∗, a conformation with ClSNS dihedral angle of 114.0°, 103.3° and 102.2°, respectively, represents the only conformer in the gas phase.

Synthesis, characterization and vibrational properties of p-fluorosulfinylaniline

The reaction of p-fluoroaniline and SOCl2 rendered p-fluorosulfinylaniline in good yield. The obtained dark yellowish liquid compound was characterized by NMR, UV-visible, FT-IR and Raman spectroscopies. The observed features were consistent with the existence of only one conformer, belonging to the CS symmetry group. A tentative assignment of the vibrational modes was performed on the basis of experimental spectra and quantum chemical calculations at different levels of theory (B3LYP and MP2 with 6-31+G(d), 6-311+G(d) and 6-311+G(df) basis sets). The conformational and vibrational properties of p-fluorosulfinylaniline were in good agreement with experimental data reported for other substituted sulfinylanilines and p-halogenanilines.