No. 4197 April 8, 1950 NATURE 565 88 per cent ethyl nitrate, a flame cannot be induced thing, and BA nothing, and a perfectly balanced on sparking. If more nitrogen dioxide is added to transfer to give a fully homopolar one-electron bond, that mixture so that its concentration is approxim• as in the hydrogen molecule-ion, to which the ately doubled, a flame can be propagated once more. +. . + The role of the methane is probably similar to that structures H H and H H make equal contributions, in the hydrogen-oxygen reaction. evidently constitutes limiting cases of a more general Acknowledgment is made to the Chief Scientist, picture of compound formation by one-electron bonds Ministry of Supply, for permission to publish this varying in type from fully homopolar to fully electro• work. static. Our ion N 2O 3+ belongs to the general case F. H. POLLARD of a partly homopolar and partly electrostatic bond : R. M. H. WYATT structure I contributes much more than II, but not H. s. B. MARSHALL everything. If we consider N,O 3+ to be produced Department of Chemistry, from NO and NO,+, we may approximately describe University of Bristol. it as having been formed through a Weiss transfer; Oct. 20. whereas, if we think of it as derived from NO+ and 'Appiu, A., Chariton, J., and Todes, 0., Acta Physicochimica Acta, NO,, then our first approximate description might U.R.S.S., 5, 655 (1936). well be that the binding arises from the incursion • Bawn, C. E. H .. and Adams, Trans. Farad. Soc., 45, 494 (1949). of exchange. • Phillips, L., Nature, 160, 753 (1947). J. D. GOULDEN • Phillips, L. (private communication). s. • Smith, J. R. E., and Hinshelwood, C. N., Proc. Roy. Soc., A, 180, C. K. INGOLD 237 (1942). D. J. MILLEN • Steacie, E. W. R., "Atom and Free Radical Mechanisms" (Amer. William Ramsay and Chem. Soc. Monograph No. 102). 'Zeldovich, Y. B., and Shavlov, Yu. Kh., J. Phys. Chem., U.S.S.R., Ralph Forster Laboratories, 20, 1359 (1946). University College, • Norrish, R. G. W., and Foord, S. G., Proc. Roy. Soc .. A. 152, 196 London, W.C.l. (1935) Nov. 23. 1 By Goulden and Millen, probably In J. Chem. Soc. The Ion N Q 3+. Binding by One-Electron 'NaJ,ure, 147, 512 (1941); Tram. Farad. Soc., 37, 780 (1941); J. 2 · Chem. Soc., 245 (1942); 462 (1943). Transfer 3 Cf. Bateman, Hughes and Ingold, J. Chem. Soc., 243 (1944). IT has been shown spectroscopically (the evidence will be published shortly') that the nitrosonium ion in solution forms a molecular compound with nitrogen + . Preparation of High Specific Activity 35 dioxide : NO NO2 (I). As the compound may also Hydrogen Sulphide ( H2S ) from Neutron• be produced from nitric oxide and a solution of Irradiated Potassium Chloride nitronium ion, one might also consider representing it . + THE recent note of U. Croatto and A. G. Maddock1 thus: NO NO2 (II). Actually, its spectral properties pointing out the desirability of producing radio indicate that it has an intermediate constitution, sulphur in its lowest, rather than in its highest, but one which much more closely resembles structure valency form, as it ordinarily occurs when pota.s::;ium I than II. Thus the high vibration frequency chloride is irradiated with slow neutrons, has prompted (2,240 cm.-1 ), depending on the multiple link in the us to comment on the method used in this lab• 35 NO-component of the complex, is displaced only one• oratory for producing H 2S from neutron-irradiated seventh of the way from the frequency of the nitro• potassium chloride. sonium ion (2,300 cm. - 1 ) towards the frequency of Neutron-irradiated potassium chloride was put in nitric oxide (1,880 cm.-1 ). a quartz container which was first evacuated and We regard the components of this compound ion then sealed with about 25 cm. of hydrogen in it. as being held together by a one-electron bond, that This container was heated to 1,100° C. for three hours. is, by the reversible electron-transfer which would and then permitted to stand overnight at 550° C. interconvert structures I and II. It is reasonable that Chemical examination of both the gas and solid phase structure I should make a. considerably larger con• showed that more than 95 per cent of the sulphur tribution than II to the wave-function of the meso- activity which was originally present in the solid phase was now in the gas phase and all of it was in the ,.I., form of hydrogen sulphide. meric complex NO,NO2 ; for the oxidation-levels of the components of I (which may be denoted by the It might be appropriate to comment at this time nitrogen-oxidation numbers 3 and 4) a.re not as on the other aspect of the letter by U. Croatto widely separated as are the oxidation-levels of the and A. G. Maddock, namely, that of the state of oxidation of the sulphur formed from the reaction components of II (the oxidation numbers of which 85 35 a.re 2 and 5). Therefore structure I should have a Cl (n,p)S • We have found that if the pre-irradiation smaller tendency to pass by a redox electron-transfer treatment of the potassium chloride is sufficiently into II, than II should have to pass into I; that is, drastic, one can alter, at least in part, the oxidation the mesomeric state will more closely resemble I. state of the radiosulphur produced•. Recently, we This case may help to clarify the position of subjected a group of potassium chloride crystals of Weiss's univalent electron-transfer theory of mole• various sizes to an outgassing procedure which con• cular compounds•, some critics of which forget that sisted of heating to 700° C., pumping with a diffusion (as Weiss implies, but does not emphasize) electron• pump for 72 hr. and then irradiating the crystals 3 in an atmosphere of hydrogen in the Oak Ridge pile. transfers are in principle always reversible • A practically irreversible one-electron transfer to form Chemical examination showed that the smallest a.n ionic bond, as in a Wurster salt, to the normal crystals had about 40 per cent of their sulphur +- activity in the - 2 state and 60 per cent in the + 6 state of which the structure .BA contributes every- state. The. fraction of activity in the hexavalent

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