Dissociation mechanism of a stable intermediate: perfluorohydroxylamine.
The mechanism of dissociation of F2NOF has been studied using density-functional (B3LYP, BB1K, and MPWB1K) and wave function methods (CCSD). Variational transition state theory was used to calculate the rate constants for cis-F2NOF --> FNO + F2 (concerted), cis-F2NOF --> F2NO + F, and cis-F2NOF --> trans-F2NOF --> F3NO. Rate constants were also calculated for the dissociation of F2NOF by using transition state theory. The enthalpies of the transitions states (CCSD(T)/cc-pVQZ//B3LYP/6-311+G(d)) were very close to the enthalpy of separated F2NO + F radicals which implies temperature-dependent competition between concerted rearrangement and fragmentation-recombination. The picture is further complicated by the fact that F2NO undergoes fragmentation into FNO + F with a very low barrier. Thus, formation of F3NO, the global minimum on the potential energy surface, can only occur by a concerted process (not from F2NO + F). The data were fit to a temperature-dependent rate in the range 200-1000 K in the form k2 = 8.14 x 10(13) exp(-7860/T) s(-1), k(1) = 6.37 x 10(13) exp(-7855/T) s(-1), and k(10) = 1.42 x 10(12) exp(-7420/T) for cis-F2NOF --> FNO + F2 (concerted), cis-F2NOF --> F2NO + F, and cis-F2NOF --> F3NO, respectively. The calculated lifetime of cis-F2NOF at 298K is 2.5 x 10(-3) s via k1.
Sayin
Hasan
H
Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA.
McKee
Michael L
ML