AMERICAN CHEMICAL SOCIETY

PRESIDENT

July 8, 1931

Professor Linus Pauling

California Inst, of Technology-

Pasadena, Calif,

Dear Professor Pauling:

Since our Secretary, Dr. Charles L. Parsons, is absent in Europe, I take this very pleasant opportunity myself to inform you of the decision of the jury on the "American Chemical Society Award in Pure Chemistry, Initiated by A. C. Langmuir". I have just been informed by the committee that you have been chosen as the first recipient of the prize to be awarded at the Buffalo meeting of the American Chemical Society.

I beg you to read the rules concerning this prize as published in the Journal of the American Chemical Society, May number, page 37; also in the News Edition of the Journal of Industrial & Engineering Chemistry for April 10, 1931. You will notice that we have to have your acceptance of the prize before it can be made public. I beg you, therefore, to communicate with me your decision as soon as you can.

Please accept my personal congratulations.

Sincerely yours,

MGomberg/m

July 10, 1931

Dr. M. Gomberg,

President of the American Chemical Society,

University of Michigan,

Ann Arbor, Mich.

Dear Professor Gomberg:

I am indeed happy to have been chosen as the recipient of the "American Chemical Society Award in Pure Chemistry, Initiated by A. C. Lengmuir," which I accept with pleasure.

In the rules concerning the prize I see that a paper or lecture is to be given at the Buffalo Meeting. Would you please let me know how long a paper I should prepare and before what gathering it is to be delivered? I should be glad also to have your advice as to the subject of the talk - should it be, say, a general review of all the work I have been doing on the nature of the chemical bond?

I am looking forward to seeing you again in Buffalo.

Very sincerely yours,

LP: M

July 17, 1931

Professor Arthur B. Lamb,

Laboratory of Chemistry,

Harvard University,

Cambridge, Mass.

Dear Professor Lamb:

I have found the paper on m-dinitrobenzene and related topics by Hendricks and Hilbert interesting. So far as I can tell, it contains no mistakes justifying refusing publication. Nevertheless, it is my opinion that it should not be published before it has been thoroughly revised. The authors may be of a different opinion, but I advise that my remarks be communicated to them with the request that they consider revision. I do not desire to criticize from behind the cloak of anonymity, and so I do not request that my identity be kept secret.

The Crystal structure of m-dinitrobenzene.

The structure reported for the crystal, with the C and N atoms in a symmetry plane and O above and below the plane, depends entirely on the assumption of holohodry. The authors mention on p. 13 that the face development shows no evidence of homihodry; however, only two forms, s and q, which would bear on the question are reported in Groth, so the evidence is not strong. They also report a negative result from a pyroclectric experiment. This evidence suggests holohodry, but by no means proves it.

I myself believe it highly probable that the point-group symmetry of the crystal is lower than D_2h. This would be by no means the first crystal found to have lower symmetry than that assigned crystallographically. My reason for not accepting the assigned structure is that the oxygen atoms are so close together. 1.91 Å might be all right for the distance within the nitro group, especially since it is possible that a bond is formed, between those two atoms, but it is surely much too small for two oxygen atoms in different molecules. The authors cannot expect any new or striking conclusions deduced by them from the assumption of holohodry to be accepted.

Following are some minor criticisms:

1. Space-group symbols should be given relative to the axes used, and preferably the full symbol (not the new abbreviated ones till some time has passed). Thus 16 - Pbnm rather than P_nma.

2. The choice of D¹⁶ _2h - P_bnm rather than D⁵ _2h - P_bnm, say, depends only on the absence of the two reflections given in the table (201) and (102). This is hardly sufficient evidence when dealing with absences.

3. I believe the error Herbel is supposed to have made should be discussed, unless it has been pointed out elsewhere.

The discussion of molecular structure.

1. Bottom of p. 6. Rupture of l-quantization will not permit five L electrons in nitrogen to have parallel spins. But removing one to an outer shell (whether l-quantization is ruptured or not) will.

2. P. 6. There is no state 2s²sp²⁵S of carbon; 2s sp^{5 5}s is meant.

3. p. 7. Pascal attributes a susceptibility of +18 x 10^-7 to oxygen in the compounds mentioned. But spin susceptibility as of the O₂ molecule, is around 2 x 10^-3 at room temperature. In other words, Pascal’s paramagnetism has nothing in common with that of molecular O₂ and can not be due to a permanently unpaired electron. Accordingly the formulas with free bonds seem unjustified.

4. I believe the formulas on pp. 8, 9, etc. should be written electronically. As given, they do not answer questions such as the following: does C or N in IV of p. 9 have the unshared pair of electrons?

5. What is meant on p. 11 by saying that nitrogen is quinauivalent in organic nitro compounds? This statement would be made definite by giving an electronic structure.

Very truly yours,

Linus Pauling

LP:M

July 30, 1931

Dr. Arthur B. Lamb,

Chemical Laboratory of Harvard University

12 Oxford Street

Cambridge, Mass.

Dear Professor Lamb:

I believe that Dr Huggins’ note is not suitable for publication in the Journal, inasmuch as there is very little evidence supporting the structures he suggests, and a strong theoretical argument against them. Hence I suggest that the note be returned him with a copy of my remarks. You need not keep my identity secret – it would be difficult to do anyway, since the note and letter from you were sent to me by Dr. Huggins himself, who had received them through the mail.

1. The evidence supporting the structure with three double bonds is that it has the proper symmetry. But ^:O: _:O::N:O:^- has the correct symmetry also, when the quantum mechanical electron distribution is examined, for the single-bond axis is a cylindrical symmetry axis. Moreover, the structure ^:O: _:O::N::O:^- with the double bond jumping from one oxygen to another has the correct symmetry, has also an ionic structure.

2. The quantum mechanics requires that only four electron pairs occupy the L shell. Hence although P and Cl and other heavier atoms may form more than four bonds, C, N, O may not, unless the much weaker eigenfunctions in outer shells are brought into play. This result, that atoms in the first row of the periodic system can form not more than four electron pair bonds, is a useful and important rule with no exceptions that I know of, and in my opinion electronic structures which are in disagreement with it are not acceptable.

3. This argument also can be used against the suggested structures for the nitro and carboxyl groups. The symmetry and the small proton-attraction are equally well explained by a structure containing one single bond and one double bond, the two changing places rapidly in accordance with the resonance phenomenon.

I shall be pleased to review the Strukturbericht. Would you let me know also at what price the book is sold?

Very truly yours,

Linus Pauling

LP:L