Kinetic and thermodynamic properties of nitrosyl iodide and nitryl iodide intermediate complexes in iodine recombination

The recombination of I atoms after laser flash photolysis was studied in the presence of NO or NO2 at 320-450 DegK and 0-200 atm of He. The reaction proceeds in 2 stages. The 1st stage is governed by the recombination I + NO (+He) -> INO (+He) or I + NO2 (+He) -> INO2 (+He), for which the full falloff curves are derived. The 2nd stage is governed either by reaction between 2 INO (or INO2) mols., or, at higher temps., by thermal decompn. of INO (or INO2). The reaction involves the elementary steps of a typical intermediate complex mechanism of atom recombination. The rates of all of these elementary steps can be sepd. From the I + NO .dblarw. INO and I + NO2 .dblarw. INO2 equil. consts. the enthalpies of formation of INO and INO2 of DHf0298(INO) = 29.0 +- 1 kcal mole-1 and DHf0298(INO2) = 14.4 +- 1 kcal mole-1, resp., are derived.