Matrix-Isolation Study of the Reaction of F Atoms with CO. Infrared and Ultraviolet Spectra of the Free Radical FCO

Abstract

X-RAY SCATTERING FOR H IN H2 3187 than j+2. The density function for the polarized H atom at Proton a has the two additional terms and !(S)=!(S)+iG 1 Pl(r,')-G 2 P2(r/) where 1']' is the cosine of the angle between s and the bond:Again by using the plane wave expansion in spherical and wavefunctions the scattering factor expression is FCO has been obtained in a CO and in an Ar matrix at 4°, 14°, and 20 0 K by the reaction with CO of F atoms produced upon photolysis of OF2, of NF2, or of t-N2F2, as well as by the photolysis of F2CO or of HFCO. The three vibrational fundamentals of the free radical FCO appear at 1855, 1018, and 626 cm-I • Experiments employing '3C '6 0 and '2C 'S O confirm the infrared identification of FCO. In ultraviolet-absorption studies on matrix-isolated FCO an extensive series of bands has been observed between 2200 and 3400 A. The most prominent progression in this system involves bands spaced at approximately 650-cm-1 intervals. It is likely that this progression is associated with the upper-state bending mode of FCO. F2CO and (FCO). are also produced in the reaction of F atoms with a CO matrix, and features of their infrared spectra are reported. A supplementary observation of the ultraviolet-absorption spectrum of gaseous F2CO shows a band system between 1800 and 2100 A, with spacings of approximately 1700 cm-I • Presumably this system is contributed by the n--->7r* carbonyl transition. The approximate geometric structure and the nature of the chemical bonds of FCO are discussed, and the mechanisms of formation of this species and of the other observed products are considered. An estimate of the thermodynamic properties of FCO is given.

Laser-induced fluorescence of the CH2CFO radical

“…The frequencies of the 8 vibration, 584 and 537 cm Ϫ1 for ground and excited states, respectively, are close to the frequency of the FCO bending vibration of FCO radicals, 627 cm Ϫ1 . 24,30,31 The frequencies of the CCO bending vibration ͑ 9 ͒, 416 cm Ϫ1 are almost equal in ground and excited states of both CH 2 CFO and CH 2 CHO. All of the experimental vibrational frequencies of the ground state of CH 2 CFO shown in Table II are smaller than the calculated values ͑Table I͒, it is generally accepted that the frequencies, , predicted by ab initio calculation are slightly higher than experimental values.…”

The Open‐Chain Trioxide CF3OC(O)OOOC(O)OCF3

“…Since a CF 3 O group behaves like a ™pseudo-fluorine atom∫, [17] shown here by comparing CF 3 OC(O)OOOC-(O)OCF 3 with FC(O)OOOC(O)F [11] and also discussed in studies of the pairs CF 3 OCO [17] /FCO [24] and CF 3 OC(O)OOC-(O)OCF 3 [13] /FC(O)OOC(O)F, [25] some still-unknown properties of the species may be foreseen: the hypothetical tetroxide CF 3 OOOOCF 3 would probably be stable at liquid-nitrogen temperature but would dissociate above this temperature into CF 3 OOO and CF 3 O, in analogy to FOOF, which decays into F and FOO; however, the pentoxide CF 3 O 5 CF 3 should not exist, in accordance with the non-existent FOOOF. [23] Experimental Section…”

The Trifluoromethoxycarbonyl Radical CF3OCO

“…However, for the FCO radical, there are two transitions to excited states and four vibrational progressions in these states that have been observed. [15,16,33] The low lying occupied molecular orbitals at the fluorine atoms of the CF 3 group are expected to interact to a negligible extent with the chromophore p-electron system of the carbonyl moiety. Therefore the CF 3 OCO radical should behave in a similar way to the CH 3 OCO radical, where no p-type orbitals are available in the CH 3 group.…”

“…[10,11] Both stable carbonate derivatives CF 3 OC(O)OOCF 3 and CF 3 OC(O)OOC(O)OCF 3 are reservoir species for CF 3 O radicals. [7] Moreover, they are used for generating CF 3 O radicals by vacuum flash pyrolysis according to Equations (14) and (15) and subsequent isolation of the products in noble gas matrices, CF (15) and for recording the complete IR and UV spectra of CF 3 O for the first time. [13] Direct observation of the CF 3 OCO radical has not been reported in the literature although its existence has been inferred.…”