Electron spin resonance spectra of the halogen hexafluorides

Abstract

The ESR spectra of ClFg, BrFg, and IFg in solid SFg have been reexamined. The observation of formally forbidden or "NMR" transitions for the latter two radicals has permitted the precise determination of their ESR parameters, hitherto known only approximately. Analysis of anisotropic spectra observed at 27 K clearly shows that the halogen hexafluorides possess Ofl symmetry. In these radicals the unpaired electron occupies an antibonding aJg orbital consisting primarily of central-atom ns and fluorine 2p" atomic orbitals. Temperature dependences noted for the line widths and hyperfine interactions are indicative of the presence of a very low-frequency deformation mode in these molecules. The results of INDO calculations for ClFg are in essential agreement with the experimental findings.

Photochemical reactions involving matrix-isolated atoms

“…When fluorine atoms are generated photochem- ically from CF3OF in solid Kr, a spectrum is obtained showing coupling to two Kr nuclei. 113 The linear KrFKr molecule has substantial spin density in the Kr(4p) orbitals (~12% each) and g± deviates considerably from free spin (gB = 2.0006, g± = 2.0657). The species Kr2F has also been observed in emission in the gas phase at high Kr pressures, but matrix emission has not been recorded.…”

“…136 The ESR spectrum of XeCl has been recorded following photolysis of Ar/Cl2/Xe matrices. 113 A major factor which limits the sensitivity of these reactions in detecting atoms, is photodissociation. HCO is dissociated by visible light (X > 400 nm)7715,122,125 as is CCO,126 while NCO, NCN, FCO, and H02 are dissociated by UV irradiation (X < 280 nm).…”

Organometallic peroxy radicals. 4. Electron spin resonance spectra of the radicals produced by reaction of organophosphorus(IV) and organoarsenic(IV) radicals with 17O-enriched oxygen

“…It is possible that these radicals are tetra-alkoxyphosphoranyloxy radicals analogous to the recently discovered F4PO' (9). This radical has, however, a smaller g-factor (2.01038) and larger phosphorus (41.1 G) and oxygen (22.8 G) hyperfine coupling constants than our species.…”

Electron paramagnetic resonance spectra of the Group 4 hexafluoride anion radicals

“…10 EPR spectra of the irradiated compounds were examined with a Varían E12 spectrometer previously described. 3 The spectrometer was equipped with an Oxford Instruments liquid helium cryostat (ESR 9).…”