Plutonium Chemistry - American Chemical Society

3 Reaction of Plutonium Metal with Diiodoethane

Downloaded by NANYANG TECHNOLOGICAL UNIV on June 3, 2016 | http://pubs.acs.org Publication Date: May 19, 1983 | doi: 10.1021/bk-1983-0216.ch003

DAVID G. KARRAKER E. I. du Pont de Nemours & Company, Inc., Savannah River Laboratory, Aiken, SC 29808

The reaction of alpha plutonium metal with diiodoethane yielded a product analyzed to be PuI C H •4THF. Heating this compound to 140 C for one hour yielded a green product, PuI C H . Ir spectra of both compounds showed the presence of ethylenic double bonds, and magnetic susceptibility showed that both were Pu compounds. From this evidence, tentative compositions for these compounds were deduced as PuI (CH =CH )‍•4THF and PuI (CH=CH ). The large, polarizable iodide ion is considered to be an important factor in stabilizing the Pu -ethylenic bonds. °

3

2

4

2

2

3

+3

3

2

2

2

2

+3

Samarium and y t t e r b i u m m e t a l s d i s s o l v e i n t e t r a h y d r o f u r a n (THF) s o l u t i o n s o f d i i o d o e t h a n e t o y i e l d s o l u t i o n s o f t h e i r d i i o d i d e s , (_1) a s Sm + l ^ H ^

T

H

F

»

Sml

2

+ C H 2

1+

The b l u e samarium d i i o d i d e s o l u t i o n s a r e s t a b l e i n d e f i n i t e l y i n t h e absence o f w a t e r and oxygen, and S m l ^ and Y b l s o l u t i o n s have b e e n employed a s r e d u c i n g a g e n t s i n o r g a n i c s y n t h e s i s . The c h e m i c a l s i m i l a r i t y between l a n t h a n i d e and a c t i n i d e m e t a l s suggests that C ^ ^ I ^ might a l s o r e a c t w i t h a c t i n i d e m e t a l s . Pre l i m i n a r y e x p e r i m e n t s found no r e a c t i o n between t h o r i u m o r u r a n i u m m e t a l s and a THF s o l u t i o n o f C H I . P l u t o n i u m and n e p t u n i u m m e t a l s r e a c t e d , b u t n o t i n t h e same manner as samarium and y t t e r bium m e t a l s . T h i s p a p e r r e p o r t s s t u d i e s o n t h e p r o d u c t s o f t h e r e a c t i o n between p l u t o n i u m m e t a l and THF s o l u t i o n s o f C H . I . 2

2

1 +

2

2

0097-6156/83/0216-0041$06.00/0 © 1983 American Chemical Society

Carnall and Choppin; Plutonium Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1983.

2

42

PLUTONIUM CHEMISTRY

Experimental Materials. THF and e t h y l e t h e r were p u r i f i e d by d i s t i l l a t i o n f r o m L i A l H . i n an a r g o n a t m o s p h e r e . T o l u e n e and p e t r o l e u m e t h e r ( b . p . , 20-40°C) were s t i r r e d o v e r n i g h t w i t h C a H and f i l t e r e d before use. A l p h a - p h a s e p l u t o n i u m m e t a l p i e c e s , p r e p a r e d at Rocky F l a t s ( R o c k w e l l I n t e r n a t i o n a l , G o l d e n , C o l o r a d o ) , were c l e a n e d w i t h a THF s o l u t i o n o f C H I b e f o r e u s e . D i i o d o e t h a n e was p u r i f i e d f r o m i o d i n e by d i s s o l v i n g i n e t h e r and w a s h i n g the e t h e r s o l u t i o n w i t h an aqueous s o l u t i o n o f s o d i u m thiosulfate. The e t h e r phase was d r i e d w i t h a n h y d r o u s sodium s u l f a t e and vacuum e v a p o r a t e d t o r e c o v e r p u r e C H I . 2


2

l +

2

2

i +

2

Analyses. P l u t o n i u m was d e t e r m i n e d r a d i o m e t r i c a l l y . A w e i g h e d sample o f a compound was d i s s o l v e d i n 2M HÔ^ w i t h a few d r o p s o f 90% HN0 t o o x i d i z e o r g a n i c m a t e r i a l , and an a l i q u o t o f t h i s s o l u t i o n counted f o r alpha a c t i v i t y . C a r b o n was e s t i m a t e d by a v a r i a t i o n o f t h e Van S l y k e method.(_2) A 30-100 mg sample was h e a t e d f o r 30 m i n u t e s w i t h 0.5 g K C r 0 , l g K I 0 , 10 mL 20% f u m i n g I^SO^ and 5 mL HÔ^ i n a c l o s e d f l a s k swept by a p u r i f i e d N s t r e a m . The N s t r e a m c a r r i e d t h e e v o l v e d C 0 to an a b s o r p t i o n s o l u t i o n o f 0.5M NaOH-0.3M NoH^. A f t e r t h e wet c o m b u s t i o n , t h e a b s o r b e d C 0 was r e l e a s e d f r o m an a l i q u o t o f t h e NaOH s o l u t i o n w i t h l a c t i c a c i d i n a m a n o m e t r i c a p p a r a t u s . Correc t i o n s w e r e a p p l i e d f o r t h e v a p o r p r e s s u r e o f w a t e r and f o r r e a g e n t blank. I o d i n e was d e t e r m i n e d by an i o d o m e t r i c t i t r a t i o n a d a p t e d f r o m W h i t e and S e c o r . ( 3 ) I n s t e a d o f the normal C a r i u s c o m b u s t i o n , i o d i d e was s e p a r a t e d f r o m t h e samples e i t h e r by s l u r r y i n g i n 6M NaOH, or by s t i r r i n g t h e sample w i t h l i q u i d s o d i u m - p o t a s s i u m (NaK) a l l o y , f o l l o w e d by d i s s o l v i n g e x c e s s NaK i n e t h a n o l . Precipitated p l u t o n i u m h y d r o x i d e s were f i l t e r e d . I o d i n e was d e t e r m i n e d i n t h e f i l t r a t e by b r o m i n e o x i d a t i o n t o i o d a t e i n an a c e t a t e b u f f e r s o l u t i o n , d e s t r u c t i o n of the excess bromine w i t h f o r m i c a c i d , a c i d i f y i n g w i t h H^SO^, a d d i t i o n o f e x c e s s K I s o l u t i o n , and t i t r a t i n g t h e l i b e r a t e d i o d i n e w i t h s t a n d a r d sodium t h i o s u l f a t e . The p r e c i s i o n o f t h e i o d i n e d e t e r m i n a t i o n i s e s t i m a t e d t o be about 5% o f t h e measured v a l u e , p r i n c i p a l l y due t o i n c o m p l e t e e x t r a c t i o n o f i o d i n e from the sample. 3

2

2

7

3

2

2

2

2

1

Measurements. I n f r a - r e d s p e c t r a f o r t h e r e g i o n 600-4000 cm"" were measured w i t h a P e r k i n - E l m e r M o d e l 710B s p e c t r o m e t e r on samples p r e s s e d i n KBr p e l l e t s . M a g n e t i c s u s c e p t i b i l i t i e s were measured w i t h a v i b r a t i n g sample magnetometer ( P r i n c e t o n A p p l i e d P h y s i c s ) as p r e v i o u s l y d e s c r i b e d . ( 4 )

P r e p a r a t i o n s . A l l p r e p a r a t i o n s , p u r i f i c a t i o n s , e t c . were p e r f o r m e d i n a p u r i f i e d a r g o n a t m o s p h e r e . The p l u t o n i u m m e t a l and a THF s o l u t i o n o f C H ^ I were s t i r r e d t o g e t h e r a t room t e m p e r a t u r e i n t h e d a r k , t o m i n i m i z e C^llÎ^ d e c o m p o s i t i o n . In a t y p i c a l p r e p a r a t i o n , a 3.0 g p i e c e of a l p h a - p l u t o n i u m m e t a l was s t i r r e d f o r t h r e e days w i t h a s o l u t i o n o f 2.1g C H I i n 50 mL THF. An 2

2

2

i +

2


3.

Reaction of Pu Metal with Diiodoethane

KARRAKER

o f f - w h i t e p r e c i p i t a t e formed i n t h e s o l u t i o n ; 1.90 g o f u n r e a c t e d Pu m e t a l was r e c o v e r e d . The p r e c i p i t a t e was f i l t e r e d , washed w i t h p e t . e t h e r , and d r i e d o v e r n i g h t a t 80°C i n vacuum. The r e c o v e r e d p r o d u c t weighed 3.70 g. The f i l t r a t e f r o m t h e r e a c t i o n c o n t a i n e d 15 mg Pu. A n a l y s e s f o u n d 25±2% Pu, 41 ± 2% I and 23±2% C, c o n s i s t e n t w i t h the e m p i r i c a l formula P u l ° i > ( > 25.53%; I , 40.70%; C, 2 3 . 0 8 % ) . A s s u m i n g f o u r m o l e c u l e s o f s o l v a t e d THF, t h e e m p i r i c a l f o r m u l a i s PuI C H «4THF. A t t e m p t s t o r e a c t Pu m e t a l w i t h C^HÎ^ i n t o l u e n e and e t h y l e t h e r s o l u t i o n s were u n s u c c e s s f u l . The s t i o c h i o r a e t r y o f the r e a c t i o n was measured by r e a c t i n g Pu m e t a l w i t h a THF s o l u t i o n o f C R l i n a s e a l e d , evacuated f l a n k . A f t e r 24 h o u r s , volume and p r e s s u r e measurements showed t h a t 1.46 mm o f gas was e v o l v e d , a f t e r c o r r e c t i o n f o r t h e v a p o r p r e s s u r e o f THF; 1.54 mm o f Pu was consumed, and t i t r a t i o n o f t h e THF f i l t r a t e found 1.8 mm o f i o d i n e . The gas c o m p o s i t i o n was not d e t e r m i n e d , b u t assuming t h a t t h e e v o l v e d gas was C H , t h e s e d a t a i n d i c a t e that the r e a c t i o n i s : c

3

3


43

2

H

1 8

Pu

3 6

1+

2

l

2

2

Pu + 2 C H 2

l +

THF I -^^PuI (C H 2

+

3

2

1 +

t+

) «xTHF +

+ 1/2

I

2

H e a t i n g t h e w h i t e r e a c t i o n p r o d u c t t o 140°C f o r one h o u r i n vacuum c a u s e d a v i s i b l e i o d i n e e v o l u t i o n and a p p r o x i m a t e l y 40% weight l o s s . No f u r t h e r w e i g h t l o s s was o b s e r v e d up t o 250°C. The gaseous p r o d u c t s f r o m t h e p y r o l y s i s were not c o l l e c t e d . The g r e e n p r o d u c t from p y r o l y s i s a n a l y z e d Pu, 43±3%; I , 50 ± 2%; C, 4.9 ± 1%. The e m p i r i c a l f o r m u l a P u I C H has t h e c a l c u l a t e d c o m p o s i t i o n Pu, 45.88%; I , 48.75%; C, 4.79%. B o t h e m p i r i c a l f o r m u l a e have h y d r o g e n c o m p o s i t i o n s a s s i g n e d t o a g r e e w i t h t h e c o m p o s i t i o n c h o s e n based on o t h e r e v i d e n c e . 2

2

3

Results IR S p e c t r a . The i n f r a r e d a b s o r p t i o n bands o f C H K I , P u I ^ H ^ T H F ( r e f e r r e d t o b e l o w as "R") and P u I C H (P) a r e l i s t e d i n T a b l e I , and t h e s p e c t r a a r e shown i n F i g u r e s 1 and 2. The s p e c t r a o f b o t h p l u t o n i u m compounds have s t r o n g a b s o r p t i o n bands a t 3400 cm" and 1600 cm" t h a t a r e i n t e r p r e t e d as due t o C-H and C=C s t r e t c h i n g f r e q u e n c i e s . The IR s p e c t r u m o f C^lÎ^ has a b r o a d complex a b s o r p t i o n from 2800-4000 cm"" and a s h a r p , s t r o n g band a t 1128 cm"" . A b s o r p t i o n i n t h e 3000 cm"" r e g i o n i s n o r m a l l y a s s o c i a t e d w i t h CH s t r e t c h i n g v i b r a t i o n s . ( _ 5 ) The normal CH s t r e t c h i s found a t h i g h e r f r e q u e n c i e s i n C=CH and C=CH groupings. The a b s o r p t i o n a t 1600 cm" i n t h e p l u t o n i u m compounds i s s l i g h t l y l o w e r t h a n t h a t e x p e c t e d f o r a C=C s t r e t c h i n g v i b r a t i o n . ( _ 5 ) The C-C v i b r a t i o n i n C H I i s f o u n d a t 1128 cm"" , and c o o r d i n a t i o n or b o n d i n g o f a C H ^ I m o i e t y would be e x p e c t e d t o l o w e r t h i s v a l u e . (6^) However, c o o r d i n a t i o n o r b o n d i n g o f a C=C l i n k a g e would be e x p e c t e d t o b o t h l o w e r the f r e q u e n c y and i n c r e a s e t h e i n t e n s i t y 2

2

1

2

2

3

1

1

1

1

2

2

1

1

2

i +

2

2



44

PLUTONIUM

TABLE

CHEMISTRY

I 1

I n f r a r e d A b s o r p t i o n Bands ( c m " ) 1

C\2

PuI C H -4THF

PuI C H

2800-4000 S, bd

3400 2900 2200 1600

3400 S 2880 W, bd

2

3

2

lf

S sh w, bd s, sp

1150 S, s p

2

1600 s p 1150 W 1100 s h

1050 s h 1000 w, bd

S,

2

s t r o n g ; M, medium; W, weak; b d , b r o a d ;

1050 M, bd 1000 s h 890 W

sp, sharp;

sh, shoulder.


KARRAKER



3.


45

46

PLUTONIUM CHEMISTRY

of t h i s band. The p r e s e n c e o f a C=C v i b r a t i o n i s c o n s i s t a n t w i t h the s h i f t o f a C H s t r e t c h from 2900 cm"" t o g r e a t e r f r e q u e n c i e s . The s p e c t r u m o f R has a b s o r p t i o n bands i n t h e 1000 cm" region t h a t can be a t t r i b u t e d t o c o o r d i n a t e d THF. (_7, 8) The b r o a d a b s o r p t i o n i n t h e s p e c t r u m o f P i n t h e 1000-1150 cm" r e g i o n i s p r o b a b l y due t o s k e l e t a l and d e f o r m a t i o n v i b r a t i o n s . ( 5 ) The absence o f a b s o r p t i o n a t 1200-1350 cm" i n d i c a t e s that there are p r o b a b l y no h y d r i d e h y d r o g e n s . ( 8 ) 1

2

1

1


1

Magnetic S u s c e p t i b i l i t i e s . The m a g n e t i c s u s c e p t i b i l i t i e s o f b o t h p l u t o n i u m compounds ( F i g u r e 3) show a weak C u r i e - W e i s s paramagne t i s m ; f o r R, u = 0 . 8 7 u , 9=2.6°K and f o r P, y f f 0 » 5 2 u , 0=1.4°K o v e r t h e t e m p e r a t u r e range 6 t o 40°K. B e l o w 6°K, t h e d e v i a t i o n of the d a t a from the s t r a i g h t l i n e i n d i c a t e s lower crystal field levels. At h i g h e r t e m p e r a t u r e s , t h e m a g n e t i s m becomes t o o weak t o measure by t h e magnetometer. These m a g n e t i c measurements i n d i c a t e t h a t p l u t o n i u m i s p r e s e n t as t h e +3 v a l e n c e i n t h e s e compounds. P u has a 5 f c o n f i g u r a t i o n , and H ground s t a t e , and w o u l d show C u r i e - W e i s s paramagne t i s m s i m i l a r t o t h e p a r a m a g n e t i s m f o u n d f o r t h e compounds s t u d i e d h e r e . (10) P u has a 5f * c o n f i g u r a t i o n and a ground s t a t e . In a c r y s t T l f i e l d o f low enough symmetry t o remove any d e g e n e r a c y , the l o w e s t c r y s t a l f i e l d l e v e l w o u l d be a s i n g l e t s t a t e , w h i c h c o u l d o n l y show t e m p e r a t u r e - i n d e p e n d e n t (Van V l e c k ) paramagne t i s m . (11) P u w o u l d be e x p e c t e d t o have a 5 f c o n f i g u r a t i o n , and a F ground s t a t e , l i k e A m . The m a g n e t i c s u s c e p t i b i l i t y f o r a FQ ground s t a t e can o n l y be t e m p e r a t u r e - i n d e p e n d e n t , i n any c r y s t a l f i e l d symmetry. 9

e f f

=

3

e

B

3 +

5

6

5 / 2

L

[ + +

2 +

6

7

3+

Q

7

Discussion To r e v i e w t h e a v a i l a b l e e v i d e n c e , t h e p l u t o n i u m i n b o t h compounds i s t r i v a l e n t , t h e compounds have c o o r d i n a t e d o r bonded e t h y l e n i c g r o u p s , and t h e e m p i r i c a l f o r m u l a e a r e Pul3C H »4THF ( t h e r e a c t i o n p r o d u c t ) and P u I C H ^ ( t h e p y r o l y t i c p r o d u c t ) . Formulae t h a t are c o n s i s t a n t w i t h t h i s e v i d e n c e are P u l ( C H = C H ) ^THF f o r the r e a c t i o n p r o d u c t , and P u I ( C H = C H ) f o r t h e p y r o l y t i c p r o d u c t . The e v i d e n c e i s o n l y s u f f i c i e n t t o p r o p o s e t h e s e c o m p o s i t i o n s , and u n t i l c o r r o b o r a t i v e measurements c a n be made, t h e s e f o r m u l a e s h o u l d be c o n s i d e r e d t e n t a t i v e . O t h e r p o s s i b i l i t i e s c o n s i d e r e d were t h a t a C ^ ^ I m o i e t y was bonding t o the P u i o n , and t h a t t h e p y r o l y t i c p r o d u c t c o u l d be a Pu compound. The f o r m e r i s i n c o m p a t i b l e w i t h t h e i r s p e c t r a , t h e l a t t e r w i t h the magnetic s u s c e p t i b i l i t y r e s u l t s . No e v i d e n c e was found f o r a h y d r i d e i o n i n the i r s p e c t r a . The p y r o l y t i c p r o d u c t 2

2

i+

2

3

2

2

2

2

3 +

2 +




3. KARRAKER

American Chemical Society Library 1155 16th St., N.W. Washington, D.C. 20036 Carnall and Choppin; Plutonium Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1983.

PLUTONIUM CHEMISTRY

48

3 +

certainly has a polymeric structure, since otherwise the Pu i n would be only 3-coordinate. The structure of the pyrolytic product probably involves extensive iodide bridging. Some speculation may be entertained on the series of reactions involved in the oxidation of Pu metal by C ^ ^ I ^ An initial step could be the attack on Pu metal by C H l2 producing a Pu * species, such as PuI *xTHF. Comparison with Sml or Ybl indicates that a Pul species would be soluble in THF. Once in solution, the Pul species would be oxidized by C H I , liberating I and precipitating PuI (C H ) *xTHFF. The low concentration of Pu in the THF solution suggests that the oxidation of Pu to Pu is a rapid reaction. Sml is not oxidized in the presence of excess Sm metal. In a similar reaction, Yb metal is oxidized first to Yb species, then to a Yb species by Me CpI«(12). Assuming confirmation by further work, these compounds are the first Pu compounds to show Pu-ethylenic bonding. The nature of this bonding is unknown, but participation of 5f orbitals with TT orbitals of the ethylene double bond, though unlikely, should be considered. The large and easily polarizable iodide ions could be the key factor in stabilizing the proposed Pu -ethylene bonds. 0

2

2

2

I+

2

2

2

2

2


3

2

1+

2

2

I+

2+

3+

2

2+

+3

5

+3

Acknowledgment This paper was prepared in connection with work done under Contract No. DE-AC09-76SROOOO1 with the U.S. Department of Energy. Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Girard, P.; Namy, J. L . ; Kagan, H. B. J . Am. Chem. Soc. 1980, 102, 2693. Steyermark, A. "Quantitative Organic Microanalysis", 2nd Ed. Academic Press, N.Y., 1961. p 454 et. Seq. White, L. M.; Secor, G. E., Anal. Chem. 1950, 22, 1047. Hoehn, M. V.; Karraker, D. G. J . Chem. Phys. 1974, 60, 393. Bellamy, L. J . "The Infra-red Spectra of Complex Molecules", 2nd Ed. John Wiley and Sons, Inc., N.Y., 1958. Chapters 2, 3, 4 and 6. Wu, T.-Y. J . Chem. Phys. 1939, 7, 965. Barrow, G. M.; Searles, S. J. Am. Chem. Soc. 1953, 76, 1175. Evans, W. J.; Meadows, J. H.; Wayda, A. L . ; Hunter, W. E . ; Atwood, J. L. J . Am. Chem. Soc. 1982, 104, 2015. The Curie-Weiss expression used here is X = C/(T+ ). Hendricks, M. E . ; Jones, E. R., J r . ; Stone, J. A.; Karraker, D. G. J . Chem. Phys. 1974, 60, 2095. Lea, K. R.; Leask, M. J . M.; Wolf, W. P. J . Phys. Chem. Solids, 1962, 23, 1381. Watson, P. L . ; Whitney, J. F.; Harlow, R. L. Inorg. Chem. 1981, 20, 3271. m

Ө

RECEIVED January 10, 1983


Plutonium Chemistry - American Chemical Society

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