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High energy excitation functions in the heavy region
76
D . M . GRUEN
of chloride ionJ 1~ Conclusions based on solution work have been reinforced by studies of reflection(~) and absorption ~a~ spectra of solid cobalt compounds like Cs2CoC14 and (HPy)~CoC14 (dipyridine cobalt tetrachloride) where the COC14= group has been identified crystallographically. In order to determine whether spectrum D represented essentially complete complexing of Co(II) by CI-, a spectrum was taken of a solution (~0"01 M) of COC12 in fused pyridine hydrochloride ~ (m.p. 144.5°C). The spectrum of this solution (spectrum E) in which Co(II) finds itself in a pure C1environment, closely resembles spectrum D. Moreover, there is a striking resemblance between spectra D and E and the main absorption band of solid Cs2CoCI~. (See Fig. 2 of reference 3.) There seems to be little doubt therefore that the pronounced absorption in the red region of the spectrum is due to the COC14= ion in fused LiK nitrate with added chloride as well as in fused pyridine hydrochloride. Recently, cryometric studies have been made of chlorocomplexes of Pb(II), Cd(II), and Zn(II) in fused NaNO3. c5~ These data were interpreted in terms of the stepwise formation of complexes M +2 ~ MCI2 -~ MCI~=. The present work indicates that Co(II) and possibly Ni(II) behave in a similar fashion in fused LiK nitrate. In order to obtain quantitative information on the Co(If) and Ni(lI) systems, a study is under way to determine the stability constants of the complexes and by making measurements over a range of temperatures to determine their heats and entropies of formation. An application of this work to the chromatography of fused salts has been described recently.(8) The help of J. B. GRUBER in the early stages of experimentation is gratefully acknowledged. The spectrophotometer compartment is based on a design of A. B. KRISCIUNAS. The author has had the pleasure of a number of fruitful discussions with L. I. KATZIN. D. M. GRUEN Argonne National Laboratory Lemont, Illinois.
(a) L. I. KATZINand E. GEBERT J. Amer. Chem. Soc. 72, 5464 (1950). I2) L. I. KATZtNand E. GEBERT ibid. 75, 2830 (1953). lal L. I. KATZlN ibid. 76, 3089 (1954). 14) L. F. AUDRIETH,A. LONG,and R. E. EDWARDS ibid. 58, 428 (1936). t~l E. R. VAN ARTSDALEN J. Phys. Chem. 60, 172 (1956). (6) D. M. GRUENNature 178, 1181 (1956).
EDITORIAL
NOTE
High Energy Excitation Functions in the Heavy Region by W. W. MEINI<~, G. C. WICI<, a n d G. T. SEABORG,3, 6 9 - 9 2 (1956). M a t e r i a l s u p p l e m e n t a r y to this article has b e e n d e p o s i t e d as D o c u m e n t N o . 4999 w i t h the A D I A u x i l i a r y P u b l i c a t i o n s Project, P h o t o d u p l i c a t i o n Service, L i b r a r y o f C o n g r e s s , W a s h i n g t o n 25, D . C . A c o p y m a y be secured b y citing the d o c u m e n t n u m b e r a n d b y r e m i t t i n g $149.25 for p h o t o p r i n t s , or $6.00 for 3 5 - m m m i c r o f i l m . A d v a n c e p a y m e n t is required. M a k e c h e q u e s or m o n e y o r d e r s p a y a b l e t o : C h i e f , P h o t o d u p l i c a t i o n Service, L i b r a r y o f Congress.
D . M . GRUEN
of chloride ionJ 1~ Conclusions based on solution work have been reinforced by studies of reflection(~) and absorption ~a~ spectra of solid cobalt compounds like Cs2CoC14 and (HPy)~CoC14 (dipyridine cobalt tetrachloride) where the COC14= group has been identified crystallographically. In order to determine whether spectrum D represented essentially complete complexing of Co(II) by CI-, a spectrum was taken of a solution (~0"01 M) of COC12 in fused pyridine hydrochloride ~ (m.p. 144.5°C). The spectrum of this solution (spectrum E) in which Co(II) finds itself in a pure C1environment, closely resembles spectrum D. Moreover, there is a striking resemblance between spectra D and E and the main absorption band of solid Cs2CoCI~. (See Fig. 2 of reference 3.) There seems to be little doubt therefore that the pronounced absorption in the red region of the spectrum is due to the COC14= ion in fused LiK nitrate with added chloride as well as in fused pyridine hydrochloride. Recently, cryometric studies have been made of chlorocomplexes of Pb(II), Cd(II), and Zn(II) in fused NaNO3. c5~ These data were interpreted in terms of the stepwise formation of complexes M +2 ~ MCI2 -~ MCI~=. The present work indicates that Co(II) and possibly Ni(II) behave in a similar fashion in fused LiK nitrate. In order to obtain quantitative information on the Co(If) and Ni(lI) systems, a study is under way to determine the stability constants of the complexes and by making measurements over a range of temperatures to determine their heats and entropies of formation. An application of this work to the chromatography of fused salts has been described recently.(8) The help of J. B. GRUBER in the early stages of experimentation is gratefully acknowledged. The spectrophotometer compartment is based on a design of A. B. KRISCIUNAS. The author has had the pleasure of a number of fruitful discussions with L. I. KATZIN. D. M. GRUEN Argonne National Laboratory Lemont, Illinois.
(a) L. I. KATZINand E. GEBERT J. Amer. Chem. Soc. 72, 5464 (1950). I2) L. I. KATZtNand E. GEBERT ibid. 75, 2830 (1953). lal L. I. KATZlN ibid. 76, 3089 (1954). 14) L. F. AUDRIETH,A. LONG,and R. E. EDWARDS ibid. 58, 428 (1936). t~l E. R. VAN ARTSDALEN J. Phys. Chem. 60, 172 (1956). (6) D. M. GRUENNature 178, 1181 (1956).
EDITORIAL
NOTE
High Energy Excitation Functions in the Heavy Region by W. W. MEINI<~, G. C. WICI<, a n d G. T. SEABORG,3, 6 9 - 9 2 (1956). M a t e r i a l s u p p l e m e n t a r y to this article has b e e n d e p o s i t e d as D o c u m e n t N o . 4999 w i t h the A D I A u x i l i a r y P u b l i c a t i o n s Project, P h o t o d u p l i c a t i o n Service, L i b r a r y o f C o n g r e s s , W a s h i n g t o n 25, D . C . A c o p y m a y be secured b y citing the d o c u m e n t n u m b e r a n d b y r e m i t t i n g $149.25 for p h o t o p r i n t s , or $6.00 for 3 5 - m m m i c r o f i l m . A d v a n c e p a y m e n t is required. M a k e c h e q u e s or m o n e y o r d e r s p a y a b l e t o : C h i e f , P h o t o d u p l i c a t i o n Service, L i b r a r y o f Congress.