May 6, 1952

Dr. John F. Tinker

Department of Chemistry

Harvard University

12 Oxford Street

Cambridge 38, Massachusetts

Dear Dr. Tinker:

I thank you for sending me a copy of your letter to Mr. Ronwin, about his paper on the structure of nucleic acid and the note that Professor Schomaker and I have published on the subject.

First, let me say that it is not a "detail" that we found defective in Ronwin's proposal. The element of novelty in his structure is the five oxygen atoms around a phosphorus atom. We mentioned that there is very strong evidence that structures of this sort are not stable. This is a fundamental criticism rather than criticism of a detail.

Our criticism might have been much more extensive. For example, it is possible to show by consideration of bond energies that the proposed structure is seriously unstable. We refrained from including this consideration, and others bearing on the question, because we thought our note might as well be as short as possible, compatible with our goal - which was to prevent biochemists from wasting time and effort on a proposal not deserving of this time and effort.

In this connection I may mention that Ronwin has found in the literature a description of the synthesis of four substances that seen to involve five oxygen atoms about a phosphorus a atom - an example is penta-phenolorthophosphate, P(OC₆H₅)₅. These substances are extremely unstable, being decomposed rapidly by moisture. This property of extreme instability in the presence of moisture is, of course, just the property that would make Romwin's proposed structure for the nucleic acids inacceptable, unless, as we stated in our note, there is an overwhelming necessity for the proposal - such necessity as to require one to assume a great difference in stability from related substances.

Professor Schomaker and I, like other workers in the field of molecular structure, know how easy it is to postulate hypothetical structures for substances. It is so easy to do this that no reputable worker in

Dr. Tinker -2- 5/6/52

the field of molecular structure publishes descriptions of hypothetical structures unless he has significant evidence in support of the structures. There is no strong evidence in favor of Ronwin's hypothetical structure, as compared with other hypothetical structures such as the one you mention in your letter.

I do not think that you are right in saying that Professor Schomaker and I criticize novelty. What we are criticizing is foolish-ness - the irresponsible publication of unsupported hypotheses. I may mention to you that some months ago I talked for several hours with Mr. Ronwin about some other ideas of his about molecular structure, and found that he has little knowledge of the precise information that has been gathered about the structure of molecules during the last twenty-five years.

In the fourth paragraph of your letter you say that perhaps I am annoyed at my own error, on page 109 of The Nature of the Chemical Bond. There is no error on this page of The Nature of the Chemical Bond. The structures of the compounds of phospherous described on this page are correct.

Sincerely yours,

Linus Pauling:W

ART/JB 6th May, 1952.

Professor Linus Pauling,

California Institute of Technology,

Pasadena 4,

California,

U.S.A.

Dear Linus,

I was very much upset to receive your letter of 28th April on my return from a brief lecture visit to Holland. I need hardly say that Alison and I are extremely disappointed that you and Helen are not going to be with us this month. In particular we are very angry indeed at the reason for your staying at home. I do not know whether you have yet seen it or not, but Robinson had a letter in the "Times" yesterday about it in which he stated in quite forthright terms what he thought about the action of your State Department, and I heartily agree with him. Indeed, if he had not written I was proposing to do something about it myself. There is, I suppose, nothing we can do about it at the present time, but the whole thing is so silly.

Thank you for your congratulations - I am not at all sure that commiserations are not more appropriate, but I am hoping that it will work out reasonably well. I think the demands on my time can be kept within bounds, and if they cannot then I shall simply resign, because I do not want to have my ordinary scientific work crippled by outside work of this type. Actually it probably sounds worse than it is because, of course, I am not doing it on a whole time basis like Tizard, and it is much more like the Chairmanship of an ordinary Government Committee than the kind of thing which, for example, Joe Koepfli is doing in Washington.

Our work here goes well, and I hope we may have an opportunity some time soon of discussing things, especially if as I hope you are getting interested in the macromolecular structure of the nucleic acids.

With best regards,

Yours sincerely,

Alex