LETTERS To the Editor: Two errors in my papers on "The Electron Repulsion Theory of the Chemical Bond" (April and May issues should be called to the attention of of THIS JOURNAL) your readers. The first, a typographical error, occurs on page 270 of the May issue where the electronic formula of the ground state of O1 is incorrect. The formula is given correctly on page 207 of the April issue. The second error was pointed out by Dean R. L. Barrett of New Mexico State University. It occurs in Figure 8 of the April issue and in Figure 2 of the May issue. As shown, the two spin-sets of the 0 atoms at each end of the molecule do not have coincident centers. The three filled-in circles on the left should be lowered and the two on the right should be raised. Then t,he filled-in set on the left and the open set on the right should be rotated slightly so that no close-pairs are shown. W. F.
~ D E R
~ O H T H E ~ S T E R UNIVERSITY N BOSTON. MASSICHUSE'T"~'~
To the Editor: Prof. Haight (J. CHEM.EDUC.,44, 465 (1967)) has presented some interesting ionization potential features developed by senior students in his inorganic chemistry classes. His paper cited several sources for the ionization data from which the studies were made. I t is perhaps noteworthy to indicate for students wishing to explore these relationships in greater depth that one of the most comprehensive and reliable sourccs, not cited by Haight, is that of C. E. Moore ("Atomic Energy Levels," Vol. I, 1949, Vol. 11, 1952, Vol. 111, 1958, NBS). These are based on extensive term analyses of optical spectra compiled over many years by many investigators. Ionization potentials up to the 19th order are listed therein, as for example in the case of the ground state for Cu(X1X) belonging to t,he Na
70 / Journal of Chemical Education
isoelectronic seauence containing 11 electrons (Vol. 11, p. 123). Employing Moore's data, the present writer explicitly derived the second order constant energy differences (CED values) (Nature, 198, 25 (1963)) and discussed their significance in relation to the periodic system of elements (Nature, 202, 1001 (1964)). The presentation of the CED law in this explicit manner is one which, to my knowledge, had not appeared previously in the literature. This law is, of course, implicit in the screening constant equation introduced by A. Sommerfeld (Ann. d. Physik, 51, 1 (1916)) and discussed in some detail by Panling and Goudsmit ("The Structure of Line Spectra," McGraw-Hill Book Co., New York, Chap. 10, 1930). HARRIMAS H. DASH
To the Editor I write to say how useful I have found the synthesis of 1-bromo-3-chloro-hiodobenzene described in THIS JOURNAL by Ault and Kraig (43, 213 (1966)). 4 s we had neither a cylinder of chlorine nor any dry ice, the chlorination of the 4-bromoacetanilide mas carried out with gaseous chlorine (generated from potassium permanganate and hydrochloric acid) which was passed into the reaction mixture until an appropriate gain in weight was registered. The iodine chloride used in the synthesis was prepared as one of a series of experiments in a general study of iodine, which shows how inorganic and organic work may be integrated with advantage. In the absence of any liquid chlorine for the synthesis of iodine chloride that preparation was carried out using a mixture of hydrochloric and nitric acids on iodine crystals, followed by extraction with ether, a method originally due to Bunsen (Ann. Chem. Phann., lxxxiv, 1). The usefulness of this synthesis is, however, not limited by its fitting in with a program on the chemistry of iodine. It also is a very good example of the many applications of acetanilide in organic syntheses ("The Usefulness of Acetanilide," Education in Chemistrg, The Royal Institute of Chemistry, London, 1966, p. 321.)
