3734
The Journal of Physical Chemistry, Voi. 85, No. 24, 198 1
I
la*
IV
hydrogen bonds, as in the cyclic dimers of H202postulated from the matrix isolation spectra.lg Further stabilization of the (H02), complex must also accrue from resonance between various electronic structures featuring single, double, and three-electron bonds between the oxygen atoms, a condition obviously lacking in the a-bonded H204 molecule. As for the disproportionation reaction, that of the (HO,), intermediate requires a shift of a mere 0.7 A of one hydrogen atom compared to that, at least three times larger, in the most favorable configuration of the H2O4 species. Incidentally, one should also consider the formation of open hydrogen-bonded dimers, H02-H02, although their lower binding energy (ca. 5 kcal mol-') may (19)P.A.Gigugre and T.K. K. Srinivasan, Chem. Phys. Lett., 33,479 (1975).
Additions and Corrections
not be sufficient to lead to disproportionation. In that connection, since some of the kinetics studies were carried out by UV absorption spectrometry, it is appropriate to recall here that the electronic spectrum of the H 0 2radical in the dimers will be somewhat perturbed by hydrogen bonding. For instance, the maximum observed a t 2100 A in the gas phase6 was found to be shifted to 2300 A in the radiolysis of aqueous solution^.^ Finally, concerning another important reaction of the hydroperoxyl radical HOz + HO -* H2O + 02 (2) the possibility of its pressure dependence has been mentioned, and the formation of the covalent species H2O39,l6 as an intermediate has been suggested.20 However, the latest measurements12 of that reaction at low pressure indicate that it is 100 times faster than reaction 1. It is unlikely, therefore, that such a fast reaction would be pressure dependent. (20)C. J. Hochanadel, T.J. Sworski, and P.J. Orgen, J.Phys. Chem., 84, 3277 (1980). Presented at the 15th International Symposium on Free Radicals, Ingonish Beach, Nova Scotia, Canada, June 2-7, 1981.
Dgparlement de Chimie Unlversitci Lava1 Quebec, Canada G1K 7P4
Received: August 19, 1981: I n Final Form: October 9, 198 1
ADDITIONS AND CORRECTIONS 1981, Volume 85 Janis L. Dote, Daniel Kivelson,* and Robert N. Schwartz: A Molecular Quasi-Hydrodynamic Free-Space Model for Molecular Rotational Relaxation in Liquids. Page 2180. The sentence in column 1 above eq A1 should read the angular velocity w1 is expressed as. Equation A5 should read
....
2 [ l + 2m(V,/Vp)'/31-4
m=l
aGW=
2 [ l + 2m(v,/vp)'/31-4
m=O
Paul A. GlguQre
