Cedric 1. Chernick
Argonne Notional Loborotory Argonne, lllinois
ttCompounds" (?) of the Noble Gases Prior to 1962
EDITOR'S NOTE: It is more than mere historical curiosity which prompts a renewed interest among chemistry teachers in the past attempts to prepare compounds of the noble gases. The fact that this has been the subject of countless assigned papers for students in inorganic chemistry courses means that hindsight is not the only motive for such interest. I n the hope that readers would appreciate having a definitive survey and reasonably complete bibliography on this theme, we are here reprinting a portion of a review paper by Dr. Cedrir L. Chernick of the Argonne National Laboratory which appeared in the September 1963 issue of Record qf Chemical Prog~ess,24, 130 (1903). We gratefully acknowledge the generous cooperation of Dr. Cherniek and the Editors of bhe Record of Chemical Pmgress. Permission has been granted for reprinting by Wayne State Ihiversity Press and Kresge-Honker Science Library Associates.
A
number of authors have made theoretical predictions concerning the possible existence of chemical compounds of the noble gases. One of the earliest is a suggestion by von Antropoff ( 1 ) who considered that the nohle gases need not necessarily have zero valence but might exhibit a maximum valence of eight. He felt that the most likely compounds would involve the heavier gases and halogens. Perhaps the most well-known prediction is that of Pauling (2) who, from considerations of ionic radii, suggested the existence of KrFe and XeFs and possibly an unstable XeFs. He also postulated that xenic acid, HaXeOs, should form such salts as AgZeOBand AgH3XeOe. However, writing some years later, he described the gas xenon as having "no ability whatever to form 0rdinar.v chemical compounds (5)." In the same year that Pauling's prediction appeared, Oddo (4) puhlished some correspondence he had had with Ramsey in which he had suggested that krypton and xenon should form halides under conditions attainable in the laboratory. Ramsey disagreed and felt it was impracticable at that time. More recently, Pimentel (5) stated that it was to be expected that rare gases could form complexes with halides and suggested helium/iodine, argon/chlorine, krypton/chlorine and krypton/bromine as the most likely mixtures to form compounds. Attempts to Prepare Compounds
The types of "compounds" reported fall into three main classes; the clathrates, the noble gas/metal compounds and the noble gas halides. The clathrates are compounds in which the noble gas atoms are held in a crystalline cage formed by some other molecule, the only bonds being weak van der Waals' forces. The hydrate of argon was prepared by Villard shortly after the discovery of the gas itself (6). This work was confirmed by de Forcrand (7), and extended to include the hydrates of krypton (8) and xenon (9). The fact that these compounds, of formula X.5.75 H1O, were clathrates was established in a series of papers by von Stackelberg, et a2. (10-15). Hydrates of krypton and xenon with heavy water have also been prepared (16). Double hydrates in which argon, krypton or xenon is the component B in a compound of the type A.2B.17 H 2 0 (17 ) and A is an organic molecule such as acetone,
carbon tetrachloride, chloroform or methylene dichloride, have been reported (17). Inanother series of compounds the clathrate cage is an organic molecule. The p-modification of hydroquinone forms clathrates with argon (18-20), krypton (21) and xenon (22). Phenol also forms clathrates with argon (to),krypton (20) and xenon (20, 25, 24). Helium and neon do not seem to form clathrate compounds, possibly because their atoms are too small to be trapped in the crystalline cage. The noble gas/metal studies have led to a series of reports of compound formation followed by refutations. The literature on this subject runs into hundreds of papers, the most prolific author being Damianovich mho with co-authors was reponsible for no less than thirty papers between 1927 and 1939. Only a few highlights of these attempts will be given here. As early as 1895 Berthelot (25-27) reported that when an arc discharge is passed through argon and carbon disulfide or benzene vapor, a brown deposit forms from which argon can be obtained. Strutt was unable t o confirm these results (28). Manley, in 1924, reported the preparation of a mercury helide (29). He had some difficulties with analyses, but eventually he reported a formula of HgHelo (SO, 31). Boomer described reactions of helium with the vapors of mercury, iodine, sulfur and phosphorus (52). Later he reported the formation of tungsten helide, WHe2,when a discharge was struck between tungsten electrodes in an atmosphere of helium at about 4-mm pressure (33). Similar work to produce platinum helide was reported by Damianovich (94). By passing helium gas over radioactive isotopes of lead or bismuth Morrison was able to trap out a radioactive gas at -78'C, and concluded he had formed a gaseous helide (55). Krefft and Rompe (36) reported spectroscopic evidence for the existence of compounds of thallium, indium, zinc, sodium, potassium and rubidum with neon, and of thallium possibly also with helium and argon. None of the evidence presented is by any means conclusive, and as recently as 1960 Waller (17) attempted to reproduce some of the electric discharge preparations, without success. Now that the existence of true chemical compounds is known, and some inhibitions have been removed, a number of these earlier experiments might bear repeating although the chances of forming noble gas-metal compounds must be considered remote. Volume 41, Number 4, April 1964
/
185
The attempts to form noble gas halides have all in( 4 7 ) All these "compounds" are transient species and have not been isolated as stable molecules. volved the heavier gases. The formation of a chloride Despite much hard and exhaustive work, the position and bromide of krypton was reported in 1932 by von early in 1962 was that no unrefutable proof had been Antropoff, Weil and Fraiienhof (37). On passing a n given for the existence of a compound in which a noble electric discharge throuzh a mixture of krypton and gas was chemically bound to another entity. Helium, chlorine or bromide, circulated through a tube with a neon, argon, krypton, xenon and radon could truly be liquid air cold trap, they noted a drop in gas pressure considere as "inert" gases. and a solid, dark-red substance condensed in the trap. However, in 1933 von Antropoff, Fraiienhof and Kruger Literature Cited (38) identified the compound as one containing nitrous A., Z. angm. Chem., 37, 217 (1924). ( 1 ) VON ANTROPOFF, oxide. A similar technique was used by Ruff and MenL., J . Am. Chem. Soe., 55, 1895 (1933). ( 2 ) PAULING, eel (39) to study the system argon/fluorine and L., Science, 134, 15 (1961). ( 3 ) PAULING, krypton/fluorine. Probably the closest to succeeding ( 4 ) ODDO,G., Gazz. Chim. Ital., 63, 380 (1933). G. C., J . Chem. Phys., 19, 446 (1951). were Yost and Kaye (do), who in 1933 irradiated a ( 5 ) PIMENTEL, ~ , C m p t . Rend., 123,377 (1896). ( 6 ) V I L L P., mixture of xenon and chlorine with ultraviolet light. R., C m p t . Rend., 135, 959 (1902). ( 7 ) DE FORCRAND, They also studied the effect of passing an electric disR., Compt. Rend., 176, 355 (1923). (8) DE FORCRAND, charge through mixtures of xenon and fluorine, and R., Compt. Rend., 181, 15 (1925). ( 9 ) DE FORCRAND, xenon and chlorine. No evidence for the formation of M., No~uTW~SS., 36, 327 (1949). ( 1 0 ) VON STACKELBERG, M., AND MULLER,H. R., Z. Elektro( 1 1 ) YON STACKELBERG, chlorides was obtained, but the evidence relating to the chem., 58, 25 (1954). xenon/fluorine reaction was inconclusive. They specu(.1 2,) VON STACKELBERG. .M... AND JAHNS. . W.,. Z . Elektrochem., 58, lated that attack on their quartz apparatus may have 40 (1954). been due to the action of a reactive xenon compound M., AND FR~JEBUSS, H., Z. Elektrochem., ( 1 3 ) VON STACKELBERG, 58, 99 (1954). and offer a comparison with rhenium hexafluoride. M., Z . Elektroehem., 5 8 , 104 (1954). ( 1 4 ) VON STACKELBERG, They did not report on a study of an irradiation of M., AND JAHNS, W., Z. Elektmchem., 58, ( 1 5 ) VON STACKELBERG, mixtures of xenon and fluorine with ultraviolet light. 162 (1954). Had they done such experiments true chemical comM.. CANQUIL,G., AND CALAS,R., C m p t . Rend., ( 1 6 ) GODCHOT, pounds of the noble gases might have been prepared 202, 759 (1936). J . G., Nature, 186, 429 (1960). ( 1 7 ) WALLRR, thirty years sooner.' ( 1 8 ) POWELL,H . M., AND GUTER,M., Natwe, 164, 240(1949). The existence of compounds of argon and boron triJ . C., Ree. Trav. Chim., 7 7 , 403 (1958). ( 1 9 ) PLATTEEUW, fluoride has been claimed by Booth and Willson (41). H. L., J. Phys. Chem., 63,1432 ( 2 0 ) LAHR,P. H., A N D WILLIAMS, &fa.rjmain .the fm~zing.nnint..~mi1~1:mnositi.on.curve 11a5Q.L . . .. . WALLER, J . G.,Natum, 186, 429 (1960). thirty years sooner.' r' EL~,-g-b;-q6'urm:--rde ~LCLYOW ~ ~ ~ a - ~ t ~POW&&, r i H .~M., AND GUTER,M., Natwe, 164, 240 (1949). NIKITIN,B. A,, C m p l . rend. acad. sci., U.R.S.S., 29, 571 krypton and xenon should form even more stable (1940); see C.A. 35, 3510 (1941). compounds. I n attempting to find these stable comVON STACKELBERG, M., Rec. lmv. ehim., 7 5 , 902 (1956). BERTHELOT, M., Compt. Rend., 120, 581 (1895). pounds Wiberg and Karbe (48) were not only unable to BERTHELOT, M., Compt. Rend., 120, 660 (1895). find the compounds of krypton or xenon, but could not BERTHELOT, M., Compt. Rend., 120, 1316 (1895). even find the argon compounds under identical condiSTRUTT, R. J., PTOC.Roy. SOC.( L a d o n ) , 80, 572 (1908). tions. Boron trichloride and tribromide are even more MANLY, J . J., Nature, 114, 861 (1924). powerful electron acceptors than the triffuoride, but MANLEY, J. J., Nature, 115, 337 (1925). MANLEY, J. J., Nature, 115, 947 (1925). neither of these react with xenon to form the type of BOOMER, E. H., Nature, 115, 16 (1925). compounds claimed by Booth and Willson (43). BOOMER, E.H., PTOC. Roy. Soe. ( L o n d a ) , 109, 198 (1925). A number of experiments have been carried out in DADIIANOVICH, H., Anales soc. espan. fm. quim., 26, 365 which a radioactive atom in a compound decays to a (1928); see C.A. 23,1537 (1929). MORRISON, D. M., Nature, 120, 224 (1927). noble gas. When the decay takes place in a mass KREFFT, H., AND ROMPE,R., Z . Physik., 7 3 , 681 (1931). spectrometer, the resulting species can be identified VON ANTROPOFF, A., WEIL, K., AND FRAiiENHOF, H., (44-46). The following are typical of the systems Natuluiss., 20, 688 (1932). studied: VON ANTROPGPP, A., F R A ~ N H OH., F ,AND KRUGER,K. H.,
-0-
CHsIlaL
(CH8Xe'3L)+
0-
C2HsIL81 ( C t H s X e l a l ) +
0-
CH,BrS2
(cH~Kld%)+
The amounts of the noble gas ions produced vary greatly as do their lifetimes which are of the order of lo-& to 10-6 sec. Similar compounds have been observed in mass spectrometric studies on high pressure mixtures of noble gases with organic molecules, and the dimeric ions of the noble Eases have also been observed Although we know today that both the photochemical and electric discharee methods can he used to form xenon fluorides, in 1933 the chances of achieving the proper conditions and of being able to isolate the material would probably have been better for the U.V. irradiation method. The attack on the quarta may have been from F2, but may well have been due to XeFs.
186
/
Journol o f Chemicol Education
Naturwiss., 21, 315 (1933). RUFF,O., AND MENZEL, W., Z. Anorg. Allgem. Chem., 213, 206 (1933).
YOST,D. M.,
AND
KATE,A. L., J . Am. C h m . Soc., 55,3890
I\----,. lQR.?)~
BOOTH,H . S.,
AND
WILLSON, K. S., J. Am. Chem. Soc., 57,
2273 (1935).
WIBERG,E.,ANDZARBE,K., Z.anorg. Chem., 256,307(1948). GREENWOOD, N. N., AND OSBORN, A. J., in "Advances in . the Chemistry of the Coordination Compounds," S. KIRSCANRR, Editor, Maemillan Co., New York, 1961. CARLSON. T. A.. AND WHITE.R. M.. J. Chem. Phys., 36, 2883 ( i 9 6 2 ) .
'
CARLSON, T. A,,
AND
WHITE,R. M., J. Chem. Phys., 38,
AND
Wmm, R. M., J. Chem. Phya., 39,
2075 (1963).
CARLSON, T. A,, 1748 (1963).
For more details on this work see: (a) COOK,G. A., Editor, "Argon, Helium and The Rare Gases," Interscience Publishers, New York, 1961; ( b ) FIELD,F . H., J. L., J . A m . Chem. Sue., 83,4509 (1961). ANDFUNKLIN,
