Isotope effects in abstraction and exchange reactions H + H′Br

✍ Scribed by J. W. Hepburn; D. Klimek; K. Liu; R. G. Macdonald; H. R. Mayne; F. J. Northrup; J. C. Polanyi

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 523 KB
• Volume: 13
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550130908

✦ Synopsis

A preliminary report is given of relative reactive cross sections for four abstraction reactions H + H'Br -HH' + Br with attacking atom (A) H or D, and atom under attack (B) H or D.

The pattern of reactive cross sections, as obtained in a crossed molecular beam experiment at a collision energy ET = 7 kcal/mol, indicates S,(D,H) >, S,(D,D) > S,(H,H) > S,(H,D).

Tile atoms in parentheses are A and B. We describe a three-dimensional classical trajectory (CT) study on a potential-energy surface proposed in 1969 by Parr and Kuppermann (PK); the CT results are in fair accord with experiment. It is suggested that (D,H) has the largest cross section because it exhibits the most favorable relative timing of A approach to BC rotation. On the basis of CT it appears that the same sequence of cross sections and the same rationale may be applied to the exchange reactions H t BrH' -HBr + H'.