JUNE, 1953
FRANZ HEIN RALPH E. OESPER University of Cincinnati, Cincinnati, Ohio
F m N z HEIN,eminent chemist and teacher, was born a t Grotzingen (Baden) on June 30, 1892. He early developed a liking for nature and natural history, together with an interest in technical matters. These interests grew logically into a choice of chemistry as a career, a choice that was particularly favored by the family's removal to Leipzig, where his father, an artist, took a teaching post. At this time Leipeig was one of the leading centers of chemical education, and the influence of Wilhelm Ostwald was still quite potent. Hein studied a t the University of Leipzig from 1912 to 1917 under Arthur Hantzsch (1857-1935) who had guided the doctoral dissertation of Alfred Werner (18661919) the founder of the coordination theory.' Hantzsch's temperamental enthusiasm for chemistry and his real scientific competence made a powerful impression on the students. His inorganic colleague was Konrad SchaePFEIFFEIL, P., J. CAEM.EDUC., 5, lOW (1928).
fer (1874-1922) who as pupil of H. h y had come to appreciate thoroughly the value of absorption spectra as a key to constitutional problems; and he, like Hantzsch, used the methods inaugurated by Hartley and Baly for the qualitative determination of absorption curves, particularly in the ~ l t r a v i o l e t . ~Consequently, Hein's dissertation, prepared under Schaefer's and Hantzsch's direction, dealt with problems whose solution demanded not only preparative skill but also familiarity with spectral methods. The thesis dealt with optical studies of bismuth compounds and triphenylmethane derivatives, topics which involved intensive occupation with both inorganic and organic chemistry. Even then, Hein began to appreciate the importance of the boundary region between the organic and inorganic fields; he realized that studies of the organoFor an outline uf Schsefer's career see HEIN,F., 2. angelu. Chern., 35,444 (19Z).
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metallic compounds and the chemistry of complexes would supply valuable insights into the chemical behavior of metals. With these points of view, he began to search for organic derivatives of chromium, a search that was rewarded by the discover)i of the phenylchromium compounds. He thus opened up a territory that has not yet been completely explored. This work was used as the basis for his habilitation as Privatdozent in chemistry at Leipzig in 1921. In 1923 he was appointed assistant professor in inorganic chemistry at this nniversity, where he had already served as assistant. About this time, he proved that substitution of organic radicals for hydroxyl in metal hydroxides generally results in bases, R.-,M"OH, that are stronger than the parent M(OH),. However, the nature of the metal is of decisive importance, and really strong bases were found onlymhen rhromiumand thallinmhydroxides were used. At the same time it was shown that the solution melts of alkali metal alkyls in zinc ethyl and related substances are good condurtors of electric current; this finding was used to demonstrate the salt nature of even the simple alkali metal alkyls. A study of the electrolysis of these compounds showed that the Faraday laws hold in these systems. Furthermore, the free slkyl radicals formed a t the anode were found to be highly active; they dissolve metals such as zinc, lead, aluminum, cadium, et,c., with production of the corresponding metal alkyl. It was also shown that metal alkyls, e. g., zinc ethyl, zinc propyl, and aluminum ethyl, provide dissociat.ing solvents not only for alkali metal alkyls but also for electrolytes as strong as quaternary ammonium iodides. These studies, like those continuing the investigation of chromium organic compounds, led, in constantly increasing measure, into the region of complex chemistry, which consequently came more and more into the foreground of his interest. One of the fruits of this part of his research efforts was the clarification of the relations between complex constitution and the capacity to form metallo-organic compounds. A new method was developed for the preparation of symmetrical organo mercury compounds in highly pure form, and also a complex chemical synthesis of up'-dipyridyl from pyridine and sublimed ferric chloride. Other studies dealt with the reactions between chromous halides and ethers, which resulted in the formation of the chromium dihalogen alcoholates, which form complexes very readily. Spatial (tetrahedral) coordination was demonstrated in the silver oxyquinoline complexes [Ag(~xine)~] X by resolving them into optically active components. Triaminotoluene was prepared and its complex chemical behavior was studied. The reactions between organo metallic bases and iron pentacarbonyl and its hydrogen derivative were investigated and, for the first time, a series of well-
JOURNAL OF CHEMICAL EDUCATION
defined organo metallo iron tetracarhonyls was ohtained. The study of the complex chemical behavior of chromous iodide finally resulted in the preparation of pure hydrasine complexes ICr(N2H&] 4. I n addition, the u,a'-dipyridyl complex salt [Cr(dip)s]12 was isolated; its characteristic behavior inspired further studies which led to the preparation, for the first time, of definite compounds of univalent chromium, e. g., [Cr(dip),]CIOc Among his other studies of metallo organics, special mention should be made of the findings regarding lead compounds. In particular, he arrived a t an explanation of the antoxidation of tricyclohexyl lead. In the presence of halogenated hydrocarbons such as carbon tetrachloride and tetrahromide the latter take a decisive part in the reaction, which may then even become explosive. The phenyl derivatives of molybdenum and tungsten were described; their stability is far less than that of the corresponding chromium compounds, and they have not been so clearly defined. The thermal decomposition of toluene in the presence of mercury led, via the formation of henzyl mercury, to the proof of the intermediate production of benzyl radicals. In the inorganic and analytical fields, he has investigated, among other topics, the behavior of silver permanganate, which because of marked deformation shows great reactivity with molecular hydrogen at room temperature. This characteristic has been made the basis of a new method- of determining hydrogen. Mention should also be made of the equilibrium studies of chromium halides. Chromons iodide was obtained in well-defined form for the first time and thus could be characterized. In the field of colloids he has contributed to the chemistry of molybdenum blue and has prepared sols and gels of chromium oxyhydrate from the ammine complexes of chromium dihalogen ethylates. His wide experience in the field of coordination compounds made it almost inevitable that he would compose a text dealing with this important and extensive field. His "Chemische Koordinationslehre" was published in 1950; this book of 683 pages has had very favorable reviews. Together with G. Bahr, he furnished the article "Wasserstoff" and "Wasser" for the Fresenius and Jander "Handbuch der analytischen Chemie." Sections on atomic weight, periodic system, systematics of inorganic chemistry, coordination theory, and isomerism of inorganic compounds, by Proskauer and Hein, were inrluded in the Drucker-Proskauer "Taschenbuch." Since 1942 Professor Hein has occupied the chair of inorganic chemistry at the University of Jena. He declined an offer in 1949 to return to the University of Leipzig, his alma mater. In 1951 he was elected to the Saxony Academy of Sciences at Leipzig.
