June 22, 1943
Dr. L. Michaelis
The Rockefeller Institute
for Medical Research
66th Street and New York Avenue
New York, New York
Dear Dr. Michaelis:
I feel some concern about your statement in your letter of June 15 that in the quinone-hydroquinone system where there is the possibility of complete resonance, the proton is in the average equidistant from the two oxygen atoms. In a certain sense this is presumably correct; however, this statement might be interpreted as meaning that the stable position of the proton is midway between the two oxygen atoms, which is, I think, not so. It is very probable instead that the proton is practically always much nearer to one oxygen atom than to the other. This point is discussed in Section 38 of THE NATURE OF THE CHEMICAL BOND. In view of the fact that the frequency of motion of the proton from one equilibrium position to another would be very small, and hence that the resonance energy resulting from this motion would also be very smell, the symmetry of systems involving hydrogen bonds is not so significant with respect to resonance energy as the symmetry of systems involving electronic resonance.
I am completely satisfied with the situation regarding acknowledgment of my suggestion. I am not discussing scientific matters with you because I want to get acknowledgement, but in the hope that I can be of some use to you in connection with your work. I shall continue to send my opinions to you, in the hope that you may find some of them useful.
Sincerely yours,
Linus Pauling
LP:jr
June
22, 1943
