Alfred Werner, son of a factory foreman, was born in Miilhausen, Alsace, on December 12, 1866. His predilection for chemistry became quite noticeable while he was still attending the lower schools, and when only
about eighteen he submitted for criticism the results of his first independent chemical investigation to Emilio Noelting, who was then director of the school of chemistry a t Miilhausen. In 1885, Werner entered the army and *Translated by Ralph E. Oesper, University of Cincinnati, Cincinnati, Ohio. The Prussian Academy of Sciences has generously authorized the publication of the translation of this biography. The original German text will appear in Deutsch~s Biographisches Jehrbuch 1917/20, Band 11. Stuttgart. 1928.
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served a term as one year volunteer a t Karlsruhe and at the same time attended Engler's lectures on chemistry a t the technical high school. The next year he moved to Zurich and in this city he made his home the rest of his life. Three eminent chemists, Lunge, Hantzsch, and Treadwell were then teaching a t the Eidgenossiches Polytecknikum (now called the Eidgenossiche Technische Hochschule) and they were responsible for Werner's excellent training. After receiving his diploma as technical chemist, 1889, he became assistant to Lunge; and a t the same time, as co-worker with Hantzsch, began the study of purely scientific problems. His doctorate thesis, "On the Spatial Arrangement of the Atoms in Nitrogen Compounds," was accepted by the University of Ziirich in 1890. Werner then spent one semester in Paris studying with Berthelot a t the College de France. On his return to Ziirich, he applied for a license to teach a t the Poly-
tecknikum, submitting with his application a dissertation, "Contributions to the Theory of Affinity and Valence." In this he disposed of many traditional notions and laid the foundations of a new valence theory. In the autumn of 1892, when only 26, he published "A Contribution to the Constitution of Inorganic Compounds," a paper which later became quite famous, for it marks its author as the founder of the modem views in this field and insures to him a rank in the history of chemical thought equal to that of August Kekul6. Only one year later, in the fall of 1893, he was appointed successor of Viktor Merz, becoming extraordinary professor of chemistry and director of chemical laboratory A a t the University of Zurich. Two years later he was promoted to a full professorship. He soon became one of the best known and most highly respected teachers and investigators at the University. Flattering offers from Vienna (1899), Basle (1902), the Eidg. Technische Hochschule (l905), and Wurzburg (1910) were declined.
Honorary doctorates were conferred on him by the University of Geneva and the Technical High School in Zurich. He was elected honorary or corresponding member of numerous scientific societies. Among the latter were the Konigliche Gesellschaft der Wissenschaften in Gottingen; the physikalisch-medizinscheSozietat in Erlangen; the physikalischer Verein in Frankfurt; the Societe de physique et d'histoire naturelle in Geneva; the Societe imperiale des amis d'histoire naturelle, d'anthropologie et d'ethnographie in Moscow; Chemical Society of London, etc. The Swiss Chemical Society honored him by establishing a Werner Fund and also issued a Werner plaquette. The highest scientific honor, the Nobel Prize, was awarded to him in 1913, and this occasioned a most enthusiastic ovation to their master by his students a t Zurich. Even a t this time, a serious disorder, arteriosclerosis, was beginning to make its destructive action evident, and a t the end of 1915 he no longer felt able to deliver the general lectures. He resumed these a t intervals but never for long, and finally the progress of the disease compelled him to relinquish his professorship in 1910. On November 15, 1919, death released this brilliant investigator, not yet fifty-three, from his distressing illness. He died while mentally deranged. Werner was a plain, sincere character, possessed of a simple, candid disposition and endowed with high intelligence and firm determination. With a prodigious capacity for work and an endurance that seemed almost inexhaustible, he persisted a t his theoretical and experimental problems, overcoming all human and material obstacles until he had reached his goal. It is obvious then that Werner was not an easy taskmaster to those working under his direction; his demands on them seemed often to reach the limits of possibility. However, this strict training has certainly been a great asset to many of his pupils throughout their entire lives. Especially in his younger years, Werner made it a practice to discuss the newer work appearing in the literature or his own investigations for hours with his assistants and he demanded that sharp criticism be exercised during these sessions. His assistants did not always find it easy to follow the trend of his thoughts, for he had a fabulous memory which extended over the whole field of chemistry, both inorganic and organic, and he could pass from one subject to another with great facility. If the topic chanced to be, say, the isomerism of inorganic complex compounds, the discussion in a few moments would very likely be centered around analogous phenomena exhibited by terpenes, alkaloids, or dyestuffs. He insisted that his auditors have clear knowledge of the constitution and configuration of the individual compounds and be able to work freely with these concepts. He personally found no difficulty in these fields as he had a remarkable faculty for envisaging spatial relationships. Under circumstances more favorable than those obtaining a t Zurich,
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this eminent investigator would doubtless have established a large school of chemical thought. Nevertheless, his Ziirich laboratory produced numerous men who occupy prominent places in the chemical industries
and a goodly number of eminent teachers. Among these are Be11, Dilthey,~Dubsky,Jantsch, Karrer, Pfeiffer, Schaarschmidt, and Stiasny. He lectured only on organic chemistry until 1902 when he also took over the inorganic division. His lectures were well prepared, original in the arrangement of the material, and characterized by the clarity with which even the most complicated problems were treated. His delivery was
convincing, and he exhibited such enthusiasm for his science that his hearers were carried with him. His teaching abilities were also evidenced by his two principal books, of which the more important is "New Ideas in Inorganic Chemistry." In this he has examined critically a vast mass of scattered data which were then, for the first time, classified systematically by means of his coordination theories. His "Stereochemistry" was also of fundamental importance, for i t was the first comprehensive, critical treatment of this important field. Even present-day investigators of stereochemical problems find it necessary to refer repeatedly to Werner's text. Werner developed a personal technic for his experimental researches on inorganic complex compounds. On his laboratory table stood several
micro-burners and micro-filter supports, together with several hundreds of small glass dishes, whose contents were of all colors. Although none of these dishes were labelled, be was quite sure that confusion was almost an impossibility. The laboratory in which he did his first work consisted of very inadequate rooms, those in the basement well deserving their popular designation, "the catacombs." In 1909, he had the pleasure of moving into a spacious new laboratory built from his own plans. From this issued, in particular, his important researches on optically active inorganic compounds. Werner's wife, nee Emma Giesker, a native of Zurich, was a member of an immigrant German family. He also showed great affection for his children, one boy and one girl. He was a very sociable soul, finding recreation from mental toil among his friends in billiards, chess, or a Swiss
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card game, jass. A few weeks of the fall vacation were usually spent in the mountains; he did not enjoy longer pleasure trips. He was an ardent attendant of scientific conventions, and frequently lectured in foreign countries. As a native of Alsace, Werner's cultural sympathies were both French and German, but he always emphasized that German science was responsible for his professional training. Of his teachers he especially revered Arthur Hantzsch. His published articles almost without exception appeared in German journals, and his hooks were also written in that language. However, his sympathies were with France during the great war. Even the first of Werner's scientific papers, his doctorate thesis, written a t the age of twenty-four, is of considerable importance since in it he laid the foundations of a new chapter of stereochemistry; namely, of nitrogen. Although published in the "Berichte" under the names of Hantzsch and Werner, the latter alone is responsible for the fundamental idea; viz., that in the numerous compounds of trivalent nitrogen (oximes, etc.), the three valence bonds of the nitrogen atom are directed toward three corners of a tetrahedron, whose fourth corner is occupied by the nitrogen atom itself. In this article, Werner successfully combated the views of V. Meyer and K. Auwers who sought to explain the isomerism of the benzil oximes by denying in this case the validity of the van't Hoff principle of the free rotation of singly hound carbon atoms about the C-C axis. His excellent extension of the van't Hoff theory of the stereochemistry of carbon has been substantiated throughout. The experimental development of his new views is due especially to Hantzsch, as Werner's participation was not for long. Problems of an entirely different kind soon absorbed his interest. Only a year after the appearance of his "Stereochemistry of Nitrogen," his habilitation essay, "Contribution to theTheory of Affinity and Valence," was published in 1891 in the Viertel jahresschrite der Zuruher Naturforschende Gesellschaft, and because of the limited circulation of this periodical the new ideas were only tardily recognized. This paper was a forerunner of Werner's masterly coordination theory. In this paper of 1891, he pursues a totally new path; he rejects the usual concept of valence as a directed single force; and assumes that affinity is an attractive force originating a t the center of the atom and acting uniformly toward all parts of the surface. (For the sake of simplicity, the atom was imagined to be spherical.) Valency for him, then, became an empirical number concept. He succeeded in deriving the van't Hoff configuration formulas without assuming directed single forces; he worked out an acceptable interpretation of stereochemical rearrangements, and attacked the benzene problem from a new angle. These ideas were developed a t greater length in 1906 in a paper, "The Variable Affinity of Simple Compounds," and in
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conjunction with Thiele's theory of partial valence have been extremely fruitful for organic chemistry. Werner's greatest achievement was without doubt the establishment of the coordination theory, with whose aid the young investigator, only twenty-six, cleared the way for a new phase of development of inorganic chemistry. According to his own statement, the inspiration came to him like a flash. One morning a t two o'clock h t awoke with a start; the long-sought solution of this problem had lodged in his brain. He arose from his bed and by five o'clock in the afternoon the essential points of the coordination theory were achieved.' The significance of Werner's coordination theory may be better appreciated if it is pointed out that chemical compounds are conveniently classified as of the first order and as of higher orders (molecular compounds). As compounds of the first order are considered all those whose molecules are made up of two distinct atomic species (chlorides, oxides, sulfides, nitrides, hydrides, etc.). In this class are also placed those substances which are derived from these simplest compounds of the first order by replacement of single atoms by either atoms of another species or by groups of atoms (radicals). This includes the vast majority of the almost inconceivably large number of organic compounds. The Keknle valence theory has proved absolutely essential in systematizing all these materials; its success is a veritable triumph. Werner rejects the application of the Kekule valence theory to molecular compounds, and to a certain extent he places them in a separate category, developing a new theoretical basis which permits of an orderly, comprehensive arrangement of even these compounds and, furthermore, his assumptions lead to a simple explanation of numerous cases of isomerism exhibited by these substances. According to Werner's hypothesis, inorganic molecular compounds contain single atoms which function as central nuclei, around which are arranged in simple, spatial geometrical patterns a definite number of other atoms, radicals, or other molecules capable of independent existence. The figure expressing the number of atoms grouped around one central atom of a molecular compound was designated by Werner as the coordination number of this atom. The concept of co6rdination number, to which are also joined the concepts of "auxiliary valence number and force" and "indirect linking," forms the central point of the Wernerian system. Only a few coordination numbers come into consideration, the most important being 3, 4, 6, and 8. The number six occurs especially often. Thousands of molecular compounds of cobalt, chromium, platinum, etc., correspond to the 6 type. In all of these, as Werner pointed out in
'
In this connection, see the article an Werner in the Sckweizerische Chnnikerzeitung for 1920. ,.
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his first paper, the spatial configuration is octahedral in that around the central metal atom lie the six coordinated atoms in the corners of an octahedron. This mode of representation was so novel and departed so widely from all previous proposals that only a few of Werner's fellow chemists recognized the import of his ideas. The chief obstacle was the "organic" orientation of the majority of the chemists of that time, for that branch of the science was then experiencing great triumphs. Werner now entered upon a twenty-year period of experimental work, whose intensity has hardly ever been equaled. He and his co-workers constantly prepared new series of molecular compounds and studied their constitutions and configurations. More than 200 dissertations were produced under his direction; his own publications exceed 150. The structure of the chemistry of inorganic complexes revealed itself in more and more harmonious form and finally, after 18 years, he made the important discovery of the optically active inorganic compounds, whose existence he had foreseen from his octahedral hypothesis. This constituted the experimental proof of one of the most important deductions of his theory, and in consequence the great significance of the coiirdination theory for chemical systematics was generally recognized. Now began the triumphant march of the coordination theory, hut its author could no longer take an active part in its progress. Starting from a study of the metal-ammonia salts and of the double salts, two classes of materials which were then not considered of particular importance or interest, this theory, while still under Werner's guidance, embraced almost the whole of systematic, inorganic chemistry and its tentacles extended into the organic field, where today its importance is commonly acknowledged. Coordination concepts are playing an increasingly important rble in crystallography, for it appears that, in general, crystals are built up in conformity with these teachings. If, in addition, it is assumed that these same considerations are valid in the theory of adsorption and of solution-though all this is still in the course of developmentthe comprehensive significance of Werner's life work follows as a matter of course. Particular interest attaches to the question as to whether Werner's train of ideas was the culmination of a lengthy logical series of developments; i. e., whether it is possible to name certain individuals who had preceded him in more or less clearly recognizing essential portions of his theories. In the writer's opinion, this is not the case. Of course, in formulating his coiirdination theory, Werner employed certain ideas arising from Kekule's valence theories, from van't Hoff's stereochemistry, and from the electrolytic dissociation theory of Arrhenius. The structure of his teachings appears, however, to have been erected as an entirely independent creation.
This becomes especially evident if Werner is compared with Jorgensen, to whom (preceding and contemporaneous with Werner) is due credit for fundamental studies of the metal-ammonia salts. Jorgensen did not wish to break away from the usual inflexible valence theories; his formulas could not give lasting satisfaction, for they aroused no incentive to a further development of chemistry. Furthermore, Jorgensen was not sufficiently informed regarding the inner, theoretical, and experimental relationship of all the various classes of molecular compounds. Mendelejeff was perfectly aware of this inherent connection. In his text "Foundations of Chemistry," which Werner knew in its German translation, he clearly emphasized the constitutional similarity of metal-ammonia salts, hydrates, and double salts; indeed he also included alloys and solutions in his discussion. However, his attempts to bring order out of this chaos were not successful, although he did demonstrate that the pure valence formulations then in vogue could not he maintained. He was also correct in his systematic placement of certain series of compounds, such as polymeric metal halides, AlxXe, etc. (which he considered as double halides). The privilege of reaching the goal toward which Mendelejeff had turned his thoughts was reserved for Alfred Werner, whose creation of the general coordination theory was the work of a genius.
Karrer, P., Helvetica Chimica A d a , 3, 196 (1920). Minner der Technik, 1925, p. 290, Herausgeber C. Matschoss; Schweizerische Chemikereeitung, p. 73, 1920. Pfeiffer, P., Zeitschriftfiir angewendte Chenzie, 33, 37 (1920). Lifschitz, J., Zeitschrift fiir Elektrockemie, 26, 514 (1920). Morgan, G . T., I. Chem. Soc. (London), 117,1639 (1920). A practically complete bibliography of Werner's publications may be found in Hehetica Chimica Acte, 3, 225 (1920).
