edited by
JOHN H. WOTlZ Southern illlnols UdvenHy Carbondale. 62901
Through the Back Door: The Role of Chance in the Choice of a Career of Two Coordination Chemists George B. Kauffman
California State University, Fresno Fresno, California 93740 Most of us would readily admit the role of chance in our choices of mates, jobs, and other crucial decisions in our lives. Similarly, a number of prominent late nineteenthearly twentieth-century coordination chemists such as Sophus Mads Jmgensen; Lev Aleksandrovich Chugaev, James Lewis, Howe, and most prominent of all, Alfred Werner were all trained as organic chemists and entered the field of inorganic chemistry only through the back door, so to speak. Today most chemists, regardless of their field of specialization, are acquainted with the name and work of Alfred Werner. Yet few realize that Werner's new and revolutionary coordination theory was based largely an experimental data carefully and painstakingly accumulated over a number of years by Sophus Mads Jdrgensen (1837-19141, Director of the Polytechnic School Laboratory and Professor of Chemistry a t the University in Copenhagen. J4rgensen devoted himself from 1878 to 1906 mostly to cobalt, chromium, rhodium, and platinum (what we now would call), coordination compounds. His epoch-making endeavors on metal-ammines emerged by chance from an apparently unrelated minor investigation "Om Paavisning af Strychnin i Urinen" (On the Detection of Strychnine in Urine) (1) which formed the basis for his doctoral dissertation "Oueriodider af Alkaloiderne" (Polviodides of Alkaloids, 1869). T h e rquantitative relati~nshi~s-hetween the ronsrituentr. of these ool\4odides were variable and complex, leading to a large number of possible compounds (2). J6rgensen then wished t o prepare similar compounds, substituting inorganic "bases" (cations) for the alkaloids. For this purpose he chose the purpureocobalt cation (chloropentaamminecobalt(III), [Co(NH3)5CoI2+), first prepared in 1847 by Frederick Augustus Genth and later characterized more fully by Gibbs and Genth (3). These'two American chemists reported that treatment of purpureocobalt chloride with cold concentrated sulfuric acid yields an apparently chlorine-free sulfate whose aqueous solution gives no precipitate with silver nitrate. Jdrgensen confirmed their observations and used the resulting sulfate to prepare his desired polyiodosulfate. On analyzing his product and finding a discrepancy between his results and the expected values, he investigated more thoroughly and found that the polyiodosulfate contains not only iodine but chlorine as well, since purpureocobalt sulfate, [Co(NH3)5C1]S04,still contained one atom of chlorine for every atom of cobalt (2). Jorgensen was so intrigued by the strange fact that treatment of purpureocobalt chloride with cold concentrated sulfuric acid removes onlv two of the three chlorine atoms, while the remaining third ?masked2') chlorine atom is not precipitated by silver nitrate, that for the rest of
his career he devoted his efforts almost exclusively to the investigation of metal-ammine complexes. The circumstances leading to the entry of James Lewis Howe (1859-1955) into the inorganic field have been related by Raleigh Gilchrist (4). Young Howe had recently returned from the University of Gottingen, where he had obtained his MA and PhD degrees under the direction of Hans Hiibner, whose primary research interest lay in,,the area of aromatic compounds. Howe's dissertation "Uber die Athylderiuate des Anhydrobenzdiamidobenzols und iiber ein Nitril desselben" (1882) therefore dealt with an organic topic, and his first two publications constituted an extension of this work. At a meeting of the American Association for the Advancement of Science, he happened to mention to Frank Wigglesworth Clarke, the eminent geochemist, that he was looking for a new research topic. Clarke told him that he could not understand why chemists persisted in devoting themselves so exclusively to carbon, an element with so few oxidation states, when so much more real chemistry could he learned from the elements of the platinum group, some of which possess as many as eight different oxidation states. This chance remark made a deep impression on Howe, who began eagerly to read the literature of the platinum metals. He decided that the most interesting and Last known metal of the group was ruthenium. Within a remarkably short time, Howe became not onlv the one outstandine American authority on and bibliographer of the metals in hut also the undisnuted world authoritv on the chemistrv of ruthenium in pa;ticular. Literature Cited (1) J6rgensen.S.M.,Kgl. D m s k e Videmkab. Sebksb Ouera., 93 (1866). (2) J#rgensen. S. M.,Ann. ehim. phys., 11. 114 (I867);J prnkt. Chrm.. 121 3.145, 328 (1873): 121 14.213.358 (1876):121 15.65.418 (1877). (3) m b s , W., end &nth. F. A . "Researchen on the Ammonia-Cobalt B m , " S m i t h nian Institution, Washington, D.C., 1856;Am. J. Sci., 121 23,285 (1856). (4) Giiehriat,R.. Chem. Re"., 32.277 11943).
An Ingenious Impudence: Alfred Werner's Coordination Theory George B. Kauffman
California State University, Fresno Fresno, California 93740 In Alfred Werner's Fackelzugrede, a talk delivered from the balcony of his home in Ziirich on November 24,1913, on the occasion of his receiving the Nobel Prize in chemistry, Werner related how an unidentified "northern colleague" of his once told him that his coordination theory had been "an
m !%on Vanderbilt (21 . . has east doubt won Kekule's dream of the cyclic structure of benzene, which he hasdescribed as "apparently the only such example in the scientific and technical literature." In the light of Vanderbilt's assertion, Werner's dream assumes even greate; importance 1 -..this ......cohrmn .
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ingenious impudence" (einegeniale Frechheit). The phrase is an apt one, for a t the time of its inception the theory was largely without experimental verification. The basic postulates of the coordination theory are well known, hut the unusual circumstances surroundina the aenesis of this theory merit wider recognition than they have received, for they provide us with a classic examole of what Alfred B. Garrett has called "the flash of genius"'(l). As such, Werner's creation of the coordination theory deserves a place in the history of chemistry that ranks with August KekulB's well known dreams of the self-linking of carbon atoms and of the benzene ring.' "The inspiration came to him like a flash," related Werner's onetime student and colleague Paul Pfeiffer, drawing on his many conversations with Werner. "One morning at two o'clock he awoke with a start: the long-sought solution of this problem had lodeed in his brain. He arose from his bed and bv five " o'clock in the afternoon the essential points of the coordination theory were achieved" (3). The accounts of two other former students, Rohert Huher (4) and Robert Wizinger (51, confirm Pfeiffer's tale. and Wizineer adds that Werner wrote the paper without interruption; forcibly keeping himself awake with strong coffee. According to Pasteur, "chance favors the prepared mind," so we might do well to try to determine how long the still unknown 26-year-old Werner had mulled over in his mind the puzzle of "molecular compounds" before the brilliant systematization of these compounds came to him in one blinding flash of visual insiaht. Aaain let us turn to Pfeiffer. "When [Werner], in the co&e orworking out a theoretical-chemical lecture, became absorbed in the prevailing theories of metal-ammonia salts and related compounds, he soon became
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convinced that conventional valence theory could not comoletelv exolain the constitution of these comoounds" ( 6 ) . s i n c e - ~ e k e rdid not begin his teaching career until the summer semester of 1892 (Aoril 19-August 6). the lecture cited by Pfeiffer could not hare taken pla& mure than a mere six or seven months hefore Werner submitted the coordintttinn theory to the Zeitschrift f i r anorgankche Chemie (December 1892). I t is ~ossiblehut extremely unlikely that Werner became interested in metal-ammines before this lecture, for he was trained as an organic chemist, and there is no indication that he ever evinced anything more than a passing interest in the inorganic field up to that time. The origin of Alfred Werner's coordination theory, then, underscores two imoortant hut overlooked points that we rvo~~ld do well to im&t to nur students: first, rhar the dream or stroke of inspiration accepted without question as a valid modus o p r a n d i for the artist is likewise characteristic of many scientists, and second, that, in the words of the distineuished historian of science. Thomas Kuhn. "almost alwavs ;he men who achieve fundamental inventions of a new paradiem have either been verv voune or verv new to the field w
