title: Fluorocarbonyl trifluoromethanesulfonate, FC(O)OSO2CF3: structure and conformational properties in the gaseous and condensed phases.
abstract: Pure fluorocarbonyl trifluoromethanesulfonate, FC(O)OSO(2)CF(3), is prepared in about 70% yield by the ambient-temperature reaction between FC(O)SCl and AgCF(3)SO(3). The geometric structure and conformational properties of the gaseous molecule have been studied by gas electron diffraction (GED), vibrational spectroscopy [IR(gas), IR(matrix), and Raman(liquid)] and quantum chemical calculations (HF, MP2, and B3LYP with 6-311G basis sets); in addition, the solid-state structure has been determined by X-ray crystallography. FC(O)OSO(2)CF(3) exists in the gas phase as a mixture of trans [FC(O) group trans with respect to the CF(3) group] and gauche conformers with the trans form prevailing [67(8)% from GED and 59(5)% from IR(matrix) measurements]. In both conformers the C=O bond of the FC(O) group is oriented synperiplanar with respect to the S-O single bond. The experimental free energy difference between the two forms, DeltaG degrees = 0.49(13) kcal mol(-1) (GED) and 0.22(12) kcal mol(-1) (IR), is slightly smaller than the calculated value (0.74-0.94 kcal mol(-1)). The crystalline solid at 150 K [monoclinic, P2(1)/c, a = 10.983(1) A, b = 6.4613(6) A, c = 8.8508(8) A, beta = 104.786(2) degrees ] consists exclusively of the trans conformer.
authors.affiliation: CEQUINOR and Laboratorio de Servicios a la Industria y al Sistema Científico, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 esq. 115, (1900) La Plata, República Argentina. carlosdv@quimica.unlp.edu.ar
authors.forename: Carlos O
authors.initials: CO
authors.lastname: Della Védova
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Downs
authors.forename: Vladimir P
authors.initials: VP
authors.lastname: Novikov
authors.forename: Heinz
authors.initials: H
authors.lastname: Oberhammer
authors.forename: Simon
authors.initials: S
authors.lastname: Parsons
authors.forename: Rosana M
authors.initials: RM
authors.lastname: Romano
authors.forename: Alex
authors.initials: A
authors.lastname: Zawadski