The Spontaneous Resolution of cis-Bis(ethylenediamine)dinitrocobalt(lll]Salts Alfred Werner's Overlooked Opportunity Ivan Bernal University of Houston. Houston, TX 77004 George 6. Kauffman California State University. Fresno, CA 93740
Around the turn of the present century, when women in science were still rarities and "Women's Lib" was undreamt of, a young Englishwoman journeyed from her home in London to carry out research in Ziirich, the beautiful old city of Zwingli and one of the leading cultural, scientific, and intellectual centers of Europe. The woman, Edith Humphrey, had chosen to work on her doctorate in chemistry under a still comparatively unknown 34-year-old Ausserordentilicher Professor named Alfred Werner (1866-1919) (Fig. 1) (1,2). Humphrey undoubtedly had been attracted by Werner's growing international reputation, for the research facilities in the old huildine a t Ramistrasse 85 (Fie. . .. 2) were woefully inadequate even as early as during Victor Meyer's trnure (1871-ldSj,(31. Werner's arowine UOUD of students was forced to workin what they aptly nicinamed the "Katakomhen" (Catacombs) (Fig. 3)-unfinished cellars and storage rooms for wood, so poorly illuminated that artificial lighting was required even a t noon (4). Yet Helmholtz's dictum that "the best works come out of the worst lahoratories" may have some degree of validity, for i t was in the Catacombs that the major portion of Werner's life work was performed. Humphrey's role in the history of coordination chemistry is twofold. First, she was Werner's first female doctoral candidate (Doktorandin) as well as his first female assistant.' ~ecund,shenssthefirstofhisstudents tosucceed in preparing M'rrner's first new series uf geometrically isomeric cobalt (51, a class ot mmpounds that were crucial in the col~~plexes develo~menrand woof of his coordination theurv (2.6). It is this second aspect of her role and a recent ironic development in the spontaneous optical resolution of her compounds (7,8) with which we are concerned in this article.
Figure 1. Werner as an atom tamer (watercolorcaricature probably by one of his students, who apparently knew nothing of the mechanism of reactions).
Geometric isomerism and Proof of the Octahedral Configuration The eenesis of Werner's coordination theorv (9). . ., in which the young 26-year-old Priuat-Dozent with virtually no experience in inoreanic chemistrvawoke in 1892 one mornine a t 2 a.m. and wrote uninterruptedly until 5 p.m. the following day (I, lo), ranks with August KekulB's alleged dream of the
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Paradoxically, although it was not until 1981 that all Swiss cantons except Appenzell had granted women the right to vote in cantonal elections (they had been allowed to vote in federal elections in 1971). the liberal and progressive Universitat Zurich has the distinction of being the first European university to admit women students (1840).During the 1870's the term "Zurcher Studentin" became a famous mark of distinction throughout the continent. Therefore it is not surprising that many of Werner's students were women. No biographical facts about Humphrey could be found,perhaps because most of Werner's students did not make any great contributions to chemistry after receiving their degrees, the cases of Paul Karrer, John Read, Yuji Shibata, and a few others notwithstanding. Furthermore, she probably married, resulting in a change in her last name. 804
Journal of Chemical Education
Figure 2. The old chemical laboratory on the Ramistrasse
benzene ring as a classic case of the flash of genius (11).An unidentified "northern colleague" of Werner's had called the coordination theory "an ingenious impudence" (eine geniale Frechheit) (12), for a t the time of its inception it was
number and type of isomers theoretically predicted for various configurations with the number and type of isomers actually prepared. By this means Werner was able to adduce strong evidence that the configuration of hexacoordinate cobalt(II1) is octahedral rather than any of the other symmetrical oossibilities (hexaeonal ulanar. hexaeonal uvrami56, 99-100; 17rpp 165-121). dal, or trigonal Since the octahedral configuration for cobalt(1II) and other transition metal cations was an integral part of the coordination theorv from its inceotion (9). oroof of this confieuration was one oI ~ e r n e r ' s goals. The geometric isomers cited by Werner on behalf of the octahedral configuration for cobalt(II1) had been prepared by others, viz., violeo (cis) and praseo (trans) [CoC12en2]CI (en = ethylenediamine) by JBrgensen (20) and flavo (cis) and croceo (trans) [CO(NOZ)Z(NH~)~]X by JBrgensen (21) and Gibbs (22). (23). . ., resuectivelv . . In 1901 Humohrev, ,(5.24) , , first described two new geometrically stereoisomeric series of cobalt(II1) salts, [ C O ( N O ~ ) ~(X ~ ~=~NOz, ] X NO3, C1, Br, I, 'IzPtCL, and SPtCls; also AuC14 (cis only)),both yellowish brown and comoletelv analoeous in constitution. confieuratlon, and chemical be.hawor Lo the p i t m e n t ~ m e dflav;) and croceo l C o W h ( N H .),I?( salrs Humohrev's . . isomers u,ere only the first ofthe dozens of series of isomers which Werner and his students were to prepare in support of the octahedral configuration for robal&lll~(2.51. \tii;h Humphrey's cumpounds Werner abandoned his '20-paper series .'Heitrag zur I
