The isokinetic relationship. V. Investigation of Bimolecular reaction systems

Abstract

The appearance of the isokinetic relationship in bimolecular reaction series is examined. It is shown that the abscissa of the common point of intersection of the Arrhenius plots is governed by the interaction of the collision complex with the surrounding heat bath and the height of the potential barrier which this complex has to overcome. The appearance of negative isokinetic temperatures (i.e. “anticompensation”) is explained and demonstrated for second-order gas phase reactions. With increasing interactions between the reactants and the heat bath (for example in condensed phase reactions) the common point of intersection is shifted towards greater reciprocal isokinetic temperatures. The theory is applied to both gas phase and liquid phase reactions, the crucial heat-bath vibrational frequencies calculated from the isokinetic temperature are found to correspond to bands in the far-infrared spectra of the solvent used as the reaction medium.