Pauling Gets Richards Medal A STAFF REPORT
WTiTH the aid of a dozen each of Cali
fornia oranges and Oregon apples to illustrate certain molecular structures, Linus Pauling delivered the Theodore William Richards medal address on May 8 before an overflowing Huntington Hall audience at Massachusetts Institute of Technology in Cambridge, Mass. Pro fessor Pauling, director of the Gates and Crellin Laboratories of the California Institute of Technology, is the ninth re cipient of the Richards medal of the Northeastern Section of the AMERICAN CHEMICAJL SOCIETY.
Prior to the medal presentation, Chester P. Baker of Northeastern University and chairman of the Northeastern Section of the ACS made a few remarks about the history of the Richards medal. Dr. Baker was followed on the program by E. BrigJit Wilson, Jr., of Harvard University, a former student of Professor Pauling, who spoke on the scientific work of the medal ist. Dr. Pauling devoted his medalist ad dress to the "unsolved problems of struc tural chemistry." In spite of the tre mendous additions that have been made to the knowledge of detailed "atomic structures of many hundreds of molecules and thousands of crystals" many im portant problems still await solution, the medalist said. Among what he termed the "puzzling small problems" the medalist included that of deciding which of two suggested structures is the correct one for the ozone molecule. Contradictory interpretations of spectroscopic data have caused some confusion by giving rise to two schools of thought on the matter. One believes that
the ozone molecule consists of two oxygen atoms very close together with a third one farther away but equidistant from the first two and loosely bonded to them. The other is that in which a central oxygen atom is attached to two equidistant oxy gen atoms with a bond angle of about 125°, corresponding to the presence of a double and a single bond in resonance. Another problem which the speaker brought up in this category was that of explaining why perbromic acid does not exist. It might be suggested, Professor Pauling said, that bromine lies in the middle of the transition from a stable acid with coordination number 4, such as per chloric acid, to a stable acid with coordi nation number 6, such as paraperiodic acid. This explanation is nullified by the existence of salts of periodic acid with co ordination number 4, the medalist declared. When Professor Pauling passed on to what he termed some of the "larger" un solved problems of structure, he included that of determining the extent to which covalent bonds between metal atoms occur in nonmetallic compounds. The medalist said that the existence of the mercury-mercury bond in the mercurous ion and in molecules such as CI—Hg— Hg—CI has been recognized. for some time, but only recently have other ex amples of this type of bond been reported. Cyril Brosset, Professor Pauling said, re ported this type of structure in the com plex ion W2CI9 within the last few years. This work was recently verified in the medalist's laboratories by Jurg Waser. The development of a systematizing or correlating theory of the color of inorganic complexes is still another task to be under
Left.. Dr. Pauling receives the medal from Dr, Baker, Right. Arthur B. Lamb, JACS editor, Mrs.
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taken, Dr. Pauling claimed. In general, he said, the theory of the color of dyes and other complex organic molecules has been well developed in recent years but existing knowledge in the inorganic field leaves much to be desired. As an example of his point the medalist referred t o the set of substances containing the same element in two different valence states resulting in abnormally deep and intense coloration. Complexes of cuprous copper with chloride ion in solution in concentrated hydro chloric acid are colorless, as is cuprous it self, he pointed out, and complexes of cupric copper with chloride ion are green. If, however, the speaker continued, the cuprous and cupric solutions are mixed, an intensely colored brown or black solu tion results due apparently t o complexes containing both of these valence states of copper. Other examples of thie same phe nomenon discussed by theratedalistwere those of compounds of antLmony, gold, iron, molybdenum, and uranium. Under the heading of "great" problems of structural chemistry, Professor Pauling included that of the structure of metals and intermetallic compounds. Some progress, he admitted, has been made in the correlation of the composition of alloys, such as the gamma alloys, with the HumeRothery ratio of valence electrons to atoms, and with the electron, numbers of "briliouin zones as calculated by quantum mechanical methods. Unfortunately, the medalist said, these advances have not been large enough to allow confident pre dictions to be made about intermetallic compounds, or to provide a satisfactory general theory of their composition, struc ture, and properties.
Theodore Richards, widow of the man whom the medal commemorates, and F. G. Key es 9 MIT
CHEMICAL
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