Werner Centennial - ACS Publications

5 Alfred Werner and Cobalt Complexes F. R. M O R R A L

Downloaded by FUDAN UNIV on November 20, 2016 | http://pubs.acs.org Publication Date: January 1, 1967 | doi: 10.1021/ba-1967-0062.ch005

Cobalt Information Center, Battelle Memorial Institute, 505 King Avenue, Columbus, Ohio

The experiments by Werner and his associates on cobalt coordination compounds accomplished two things: they in creased the chemical knowledge in this extensive area (more than 700 compounds) and helped Werner develop his ideas on coordination theory and stereochemistry. It was only after he had received the Nobel Prize (1913) and after his death (1919) that his ideas of primary and secondary valence were confirmed. Unfortunately, Werner's span of active life was short (1893-1915). A listing is given of his co-workers who researched cobalt compounds. These resulted in 52 papers by Werner, 75 with co-authors, and at least 10 unpublished theses. Research to 1960 on cobalt coordination compounds has been summarized in "Gmelins Handbuch der anorganischen Chemie" (1963).

A l f r e d Werner (December 12, 1866-November 15, 1919) during his professionally active life (1893-1915) contributed extraordinarily to the knowledge of cobalt coordination compounds. These compounds, no doubt, helped him develop his ideas that resulted i n the two theories that made him a leader i n two phases of twentieth century chemistry: coordina tion theory and stereochemistry. Werner presented his coordination theory in 1893, and his investiga tions and thoughts on cobalt compounds were presented i n a series of 52 papers authored b y him and 75 papers with associates (Table I). T h e names commonly used for these compounds are: complex ions, Werner complexes, coordinated complexes, coordination compounds, or simply complexes. H i s first lecture on cobalt compounds was probably the one given on "Neue Kobaltiake," September 1896, before the Schweizerische Naturforschende Gesellschaft of Zurich. A most important lecture in his life was no doubt his acceptance of the 1913 Chemistry Nobel Prize U) in 70 Kauffman; Werner Centennial Advances in Chemistry; American Chemical Society: Washington, DC, 1967.


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Cobalt Complexes

Stockholm, Sweden. The last lecture, as the first, was given i n Geneva, September 14, 1915, before the same society on "Cobalt Compounds with Asymmetric Cobalt and C a r b o n . " It is perhaps significant that 12 of his papers i n the Berichte between 1911 and 1914 carried the title "Toward the Knowledge of the Asymmetric Cobalt A t o m . " A t least seven other lectures on cobalt compounds were given by Werner to national and inter national meetings (2). The most important of these papers is now avail able i n translation (3). It is suspected that some researches on the cobalt compounds were not published i n the years that Werner spent as a professor at Zurich (1893-1919) and are recorded only i n theses at the University of Zurich (Table II). Shortly after his death, two of his biographers (1, 6) mention that more than 200 thesis investigations had been made under his inspiration and supervision. In 1898 there appeared an English translation of Werner's "Stereo chemistry Among Inorganic Substances" (7). In this paper he pointed out that for "molecular compounds" constitution cannot be presented with the aid of valence unless one resorts to several secondary hypotheses, each applicable to only a limited number of compounds. H e illustrated the differences i n the chemical behavior of C o ( N H ) C l and C o ( N H ) 5 C l , as well as i n their electrical conductivity i n solution. H e called attention to the series of intermetallic compounds intermediate between true molec3

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Samples of tris[tetrammine-p-dihydroxocobalt(III)]cobalt(III) salts, the first carbon-free coordinate compound to be resolved, 1914

Kauffman; Werner Centennial Advances in Chemistry; American Chemical Society: Washington, DC, 1967.

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Table I. Co-Author


Year

1893-1896

A. Moliati

1897

P. Ferchland A. Klein R. Klein

1898

A. Mylius F. Beddow H . Griiger F. Steinitzer

1899

W. Spruck A. Vilmos

1900

F. Braunlich R. Klien H . Miiller

1901

L. A. C. E.

1903

N . Goslings

1904-1905

A. E. R. A.

1906

R. Feenstra E. Bindschedler

1907

E. Berl G. Jantsch E. Zinggeler A. Baselli F. Braunlich F. Rogowina K . Dawe A. Frohlich G. Jantsch C. Kreutzer E. Zinggeler

1910

Gerb Gubser H . Herty Humphrey

Griin Berl Feenstra Wolberg

E. Bindschedler & E. Welti

Cobalt Compounds (/) Year

Co-Author

1910, con't.

J. Furstenberg M . Grigorieff E. Kindscher A. Salzer M . Pieper F. Steinitzer & K . Rucker

1911

V. L. King E. Scholze

1912

W. E. Boes L. Gerb, S. Lorie & J . Rapiport H . Hartmuth R. Bosshart F. Chaussy L. Cohn

1912

McCutcheon K . R. Lange P. Larisch G. Lindenberg M . Pokrowska C. Rix Y . Shibata R. Samanek G. Tschernoff

1913

M . Basyrin

1914

E. Bindschedler & C. Sackur R. Bosshart W. J . Bowis, A. Hoblik, H . Schwarz, & H . Surber H . Kuh & P. Wust

1915

E. Blatter, C. Sackur, H . Schwarz, & H . Surber

1918

P. Karrer S. Matissen

1921

J . E. Schwyzer & P. Karrer


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ular compounds and double salts (double chlorides, fluorides, nitrites, etc.). H e wrote, "There can be no doubt that the first salt contains three atoms of chlorine identical in properties and acting as ions, while the second contains only two that can act i n that way. " W e have now to get an idea of the configuration of these groups M A ; the most simple hypothesis that can be formulated is an octahedral arrange ment, the metallic atom occupying the center of the octahedron. The six groups A will have their places at the corners. " I t is evident that this arrangement should give rise to certain cases of stereomerism, of which we shall consider at present only one, which experiment confirms."


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From G . B. Kauffman, "Alfred Werner—Founder of Coordination Chemistry," SpringerVerlag, Berlin-Heidelberg-New York, 1966

Werner as a young Privat-Dozent, 1892 or 1893

Werner and his co-workers (Tables I and II) proceeded i n a very systematic fashion, and a series of cobalt compounds was not only made but was also identified, and properties were noted or measured (color, chemical reaction, electrical conductivity, and optical properties). Some of his students and co-workers continued to investigate cobalt compounds after having accepted positions i n other universities or returned to their native countries.


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Table II.

Theses at the University of Zurich on Cobalt Compounds, 1893-1921 Gmelins Handbuch (Page)

Year

Name

1904

P. Larisch

48, 133

"Uber die Abhangigkeit der Ldslichkeit von der Anzahl der Ionen bei den Kobalt-Chrom-, Rhodium-, Iridium-, und Platin-Ammoniaken"

1912

A. Gordienke

52, 56, 77, 88, 112, 149, 251, 252, 263, 353

"Untersuchungen uber die Beziehungen zwischen Farbe und Konstitution chemischer Verbindungen"

1913

H . Seibt

149, 227, 228

"Uber stereoisomers Difluoround Fluoro-ammin-diaethylendiaminkobaltisalze''

1914. J . Angerstein

74, 75, 77, 79, 100, 125, 135, 152, 155, 283, 353, 360

"Uber die Absorptionsspektren von Metallammoniaken"

1915

W. Tupizina

242, 272

"Untersuchungen uber die optische Aktivitat von Kobaltverbindungen"

1919

R. von Arx

86, 183, 272

"Uber aktive Isorhodanatommindiathylendiamin - Kobaltisalze"

0. Datwiler

264

H . Fischlin

168, 169, 170, 259, 260

I. Wilbuschewitsch

140, 260, 270

"Zur Kenntnis der optisch-aktiven a's-Bromonitrodiaethylendiamin-Kobaltisalze'' "Uber optisch aktive Chloroaquodiaethylendiaminkobaltisalze" "Uber Diacido-diaethy lendiaminkobaltisalze"

C. Schleicher

52

1921

Subject

"Uber Absorptionsspektren von Komplexsalzen"

"Gmelins Handbuch der anorganischen Chemie," Eighth Edition, System No. 58, Part B , 1930, on "The Amines of Cobalt," is the only one of the separate volumes on metal amines in Gmelins' series that includes Werner's work. This book refers to the literature from 1799, the year of the discovery of the first cobalt-ammonium salt, to the year 1929. In this volume of 376 pages, more than 2400 cobalt compounds are listed, 700 of which refer to Werner and his associates. Some additional compounds and special investigations are available but, as mentioned earlier, are only


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available i n thesis publications (Table II). The work on cobalt coordina tion compounds to 1960 has been summarized in "Gmelins Handbuch der anorganischen Chemie, System 58, Supplement to Part B , Section 1, 1963, and Section 2, 1964. Although Werner's new chemical concept was developed i n 1892 when he was only 26 years old and a Privat-Dozent at the Zurich Polytechnikum, general acceptance did not come until 1911. That year was probably the high point of Werner's career because it was then he resolved the racemic molecules of the 1,2-chloroammine bis (diethylenediamine) cobalt (III) salts. This discovery shook the chemical theory of the time. W i t h this he proved the octahedral formula of a metal compound with 6-coordinate valency, for only this arrangement explained optical symmetry which he had proposed many years before. W i t h cobalt (III) complexes, all possible stereochemical changes have been observed. It is remarkable that Werner obtained his results by isolating the products of the reaction and estimating qualitatively the ratio of the isomers produced. It is significant that Werner devised his concepts by considering the conductivity behavior and geometry of central metal atoms. H e carefully tabulated lists of known compounds of the ammonia-complex type. Note the cobalt compounds listed on the abcissa i n Figure 1. B y using the metal as a central element, Werner surrounded it with a constant number— six molecules or ions in the case of cobalt compounds. H e suggested that the attractions that held these molecules and ions to the central metal were secondary valences, which he termed "coordination number." The evi dence for his interpretation was the conductivity behavior of these com pounds (Figure 1). The conductivity is highest for those compounds that ,,


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dissociate into the largest number of ions (considering the part within the square brackets as forming only one ion). As a negative ion enters the coordination sphere, the conductivity falls, reaching a zero value for [ C o ( N H ) ( N 0 ) ] , where dissociation is no longer possible. 3

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Courtesy Frau Dr. Anna Elisabeth Ernst

Werner at his desk, ca. 1905

Besides explaining the ammonia complexes in this manner, Werner extended the same kind of reasoning to hydrates, cyanides, thiocyanates, amine complexes, cyanates, carbonyls, and similar compounds. H e also reasoned that there must be isomerism owing to the arrangement of ions in the inner, or coordination, sphere and the outer sphere where or dinary, or primary, valence relations hold—e.g., [ C o ( N H ) C L ] B r 2 and [Co(NH ) Br]ClBr. Treating the 6-coordinate spheres i n geometrical fashion, Werner demonstrated the possibilities for cis and trans isomerism. If the metal 3

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Cobalt Complexes

is considered to be at the center of a regular octahedron, the coordination valences will be directed to the six corners, giving two possible arrangements for the compound of the type M A B . According to Werner, then, a metal atom can combine with a definite number (usually four or six) of other atoms, ions, or molecules and coordinate them into a definite geo metrical arrangement about itself. While Werner's ideas of primary and secondary valence were not well received during his lifetime, shortly after his death (1920) they were con firmed by Kossel, who laid the foundation for the electronic theory of valence. Furthermore, at about the same time, Wyckoff and Dickinson both confirmed Werner's theory by x-ray diffraction studies of these types of compounds. It is of interest that covalent compounds of bivalent cobalt can de compose H 0 with liberation of H , whereas the trivalent cobalt ion decom poses H 0 , liberating 0 , being one of the most powerful oxidizing agents known (5). These materials should have a use in modern aerospace problems. In summary, it is now agreed that coordination concepts are valuable in explaining a wide variety of inorganic phenomena of theoretical and practical nature, such as the stabilization of unusual oxidation states, analytical implications of metal complexes, and the industrial use of complexing agents. Aside from the ammines and the hydrates, discussed mostly by Werner, there are many important types of coordination com pounds, such as complex cyanides of heavy metals, metal carbonyls (formed in the catalysis of petroleum products and used to produce metals), and others. The three symposia i n 1 9 6 6 are the tribute to Werner of a grateful generation of chemists. As a result many papers will be published in addition to two new books on his life and works (#, 3).


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Literature

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Cited

(1) Karrer, P., Helv. Chem. Acta 3, 196 (1920).

(This has an extensive, but

not

complete, bibliography of Werner's publications.) (2) Kauffman, G. B., "Alfred Werner — Founder of Coordination Chemistry," Springer-Verlag, Berlin-Heidelberg, New York, 1966. (3) Kauffman, G. B., Editor, "Classics in Coordination Chemistry. Part I. The Selected Papers of Alfred Werner," Dover Publication Company, New York, 1966.

(4) "Nobel Lectures in Chemistry, 1901-1962," Nobel Foundation, 1 (1901-1921), American-Elsevier Publication Company, Inc., New York, N . Y . , 1966. (5) Noyes, A. A., Deahl, J. J., J. Am. Chem. Soc. 59, 1337, 1937. (6) Pfeiffer, P., J. Chem. Educ. pp. 1090-1098, September, 1928.

(7) van't Hoff, J. H . , "The Arrangement of Atoms in Space," p. 185, Second E n larged Edition, Longmans, Green and Company, New York, 1898 (with appen dix by A. Werner). R E C E I V E D May 31, 1966.


Werner Centennial - ACS Publications

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