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of 15 cm in a closed circulating system. The exchange reaction proceeded reversibly in the following manner over t,he dicyanoquinone-phenothiazine complex
where HZ represents the EDA complex. When an equimolar mixture of CzDz and CzHz was employed, the over-all reaction to form CzHD from C2Dz and CZH could be observed over the complex. The three components in the gas-CzHz, CZHD, and C2Dz-were analyzed quantitatively by infrared spectroscopy. A series of measurements was also carried out by introducing CzDz only onto the complex surface. An activation energy of approximately 10 kcal/mole is observed for both exchange processes. Comparison of the rates of the two exchange reactions, CZHZ CzDz = 2CzHD and C2D2 HZ = C2HD DZ, revealed that the former reaction proceeds via steps 1 and 2. In the case of the TCNQ-phenothiazine complex, the reaction proceeded initially for a short time and then stopped at room temperatures, while a considerable amount of C2HD was evolved at temperatures near 75". No reaction took place over the pyromellitic dianhydride- and trinitrobenzene-phenothiazine complexes, probably because they are comparatively weak electron accept,ors. Dicyanodichloroquinone and pchloranil, on the other hand, are strong electron acceptors, but no reaction proceeded over their complexes with phenothiazine, presumably because they contain no hydrogen in their molecules. The exchange reaction proceeds neither on the phenothiazine nor on those electron acceptors alone even a t temperatures as high as 120", which leads to the conclusion that the formation of EDA complex resulted in a marked reactivity in the case of dicyanoquinonephenothiazine complex. The film of the dicyanoquinone-phenothiazine complex was also prepared from the mixed solution in tetrahydrofuran. The rate of the exchange reaction over the film was of the same order of magnitude with that over the evaporated complex film. The irradiation by ultraviolet light showed no effect on the exchange rate within experimental error. The hydrogen exchange reaction for molecular hydrogen instead of acetylene did not proceed over the complex at 130'. However, it is interesting to note that the isomerization of cis-2-butene proceeded slowly at 120" to trans-2butene, but not to l-butene, over the dichlorodicyanoquinone- and dicyanoquinone-phenothiazine complexes.
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The pure calcium carbide employed in the prepsration of deuterioacetylene was prepared by Dr. N. Torikai of the Yokohama National University from pure calcium oxide and ashless carbon, for which the authors' thanks are due. DEPARTMENT OF CHEMISTRY MASARU ICHIKAWA OF TOKYO MITSUYUKI SOMA THEUNIVERSITY HONGO, BUNKYO-KU TAKAHARU ONISHf KENZI TAMARU TOKYO, JAPAN RECEIVED JUNE30, 1966
Electron Spin Resonance of Hydrocarbon Dianion Radicals
Sir: We wish to report on the electron spin resonance of fluorene, 9-phenylfluorene, benzofluorenes, 4,5methylenephenanthrene, carbazole, and 4,5-iminophenanthrene dianion radicals and the correlation of the observed hyperfine splitting with calculated spin densities. The observed coupling constants are given in Table I according to the following numbering system
The assignment of coupling constant
