Tetrafluorosulfate(1-) and tetrafluorooxosulfate(1-) radical anions (SF4- and SF4O-)

• Published in: Journal of the American Chemical Society 1993-02, Vol.115 (3), p.1129-1134
• Main Authors: Christe, K. O, Dixon, D. A, Goldberg, I. B, Schack, C. J, Walther, B. W, Wang, J. T, Williams, F
• Format: Article
• Language: English
• Subjects: 400201 - Chemical & Physicochemical Properties; 400600 - Radiation Chemistry; ALKALI METAL COMPOUNDS; ANIONS; Atomic and molecular physics; CESIUM COMPOUNDS; CHARGED PARTICLES; DATA; ELECTROMAGNETIC RADIATION; ELECTRONIC STRUCTURE; Exact sciences and technology; FLUORIDES; FLUORINE COMPOUNDS; GAMMA RADIATION; General molecular conformation and symmetry; stereochemistry; HALIDES; HALOGEN COMPOUNDS; INFORMATION; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; IONIZING RADIATIONS; IONS; MATHEMATICAL MODELS; Molecular properties and interactions with photons; MOLECULAR STRUCTURE; NUMERICAL DATA; Physics; Properties of molecules and molecular ions; RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; RADIATIONS; RADICALS; SPECTROSCOPY; SULFUR COMPOUNDS; SULFUR FLUORIDES; THEORETICAL DATA
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00056a043

The novel radical anions SF[sub 4][sup [minus]] and trans-SF[sub 4]O[sup [minus]] were generated by [gamma]-irradiation of CsSF[sub 5] and CsSF[sub 5]O, respectively, at [minus]196[degrees]C and characterized by their isotropic EPR spectra at +27[degrees]C. The SF[sub 4][sup [minus]] anion (g = 2.0045, a33[sub S] = 12.85 mT, a19[sub F] = 9.75 mT) has a square-planar structure close to D[sub 4h] symmetry derived from a pseudo-octahedron in which the two axial positions are equally occupied by a total of three sterically active valence electrons. Accordingly, the greatest portion of the unpaired electron spin is localized in a sulfur p[sub z] orbital. The trans-SF[sub 4]O[sup [minus]] anion (g = 2.0027, a33[sub S] = 36.26 mT, a19[sub F] = 18.95 mT) has a closely related, pseudo-octahedral structure of C[sub 4v] symmetry in which the equatorial positions are occupied by four equivalent fluorines, one axial position is occupied by a doubly bonded oxygen, and the second axial position is occupied by the sterically active free valence electron. Accordingly, the greatest portion of the unpaired electron spin is localized in an axial sp-hybrid orbital of sulfur. The structures and electron spin density distributions of SF[sub 4][sup [minus]] and cis- and trans-SF[sub 4]O[sup [minus]] were analyzed by a local density functional study which also provided vibrational frequencies and charge distributions for these radical anions. For comparison, the closely related SF[sub 5] radical, the cis- and trans-PF[sub 4]O[sup 2[minus]] radical anions, and the SF[sub 4], SF[sub 4]O, and SF[sub 6] molecules were also calculated by this method. These calculations show that the exclusive formation of trans-SF[sub 4]O[sup [minus]] under the experimental conditions is probably due to both energetic and reaction mechanistic reasons and that the agreement between the LDF calculations and the experimental data is good. 44 refs., 2 figs., 5 tabs.