Synthesis, spectroscopic and structural properties of trichoromethyl trifluoromethanesulfonate

M. E. DEFONSI LESTARD; L. A. RAMOS; M. E. TUTTOLOMONDO; S. E. ULIC; A. BEN ALTABEF

Florencia, Italia

Congreso; EUCMOS 2010, European Congress on Molecular Spectroscopy; 2010

Trichoromethyl trifluoromethanesulphonate, CF3SO2OCCl3, was synthesized by reacting Ag (OSO2CF3) and BrCCl3. This compound was characterized by NMR (13C, 19 F) and vibrational spectroscopy. Quantum chemical calculations1 were used to predict the geometry of the most stable conformation of CF3SO2OCCl3. Potential energy curves around the S-O bond were calculated at the MP2 and DFT (B3LYP and mPW1PW91) levels with different basis sets. Two structurally equivalent conformers were identified with C1 symmetry and gauche conformation (CSOC dihedral angle of about 130º). The shallow rotational barrier between both conformers is 4 kJmol-1 at B3LYP/6-311++G(d,p) level. This result is in agreement with geometric parameters of other covalent sulphonates. This conformational preference was analyzed using the total energy and natural bond orbital partition schemes. Additionally, the total potential-energy was deconvoluted using six fold Fourier-type expansion. The infrared (gas and liquid) and Raman (liquid) spectra of CF3SO2OCCl3 allowed to assign 28 of the 3N-6= 30 fundamental vibrational modes. The harmonic vibrational wavenumbers and the force field were also calculated.