The estimation of a factors for atom fissions in polyatomics

It is shown that A factors for atom fissions in polyatomics can be reliably estimated by an improved version of the restricted free rotor model (RFRM). No adjustable parameters are used in the evaluation of A factors for the dissociation of the ROF bond (R: NO 2 , SF 5 , CF 3 , FSO 2 ), and the authors' predictions are compared with high‐pressure kinetic data for these reactions. In the case of O 2 NOF, for which full spectroscopic information is available, RFRM reproduces the observed value A m well within a factor of 2. Similar agreement is reached for F 5 SOF and FO 2 SOF, assigning reasonable limits to their OF torsional frequencies. For F 3 COF, A m and the calculated back reaction rate constant, which is independent of the model, are both much too small to be plausible, suggesting falloff effects rather than a failure of RFRM.