10
Room Temperature Fused Salts: Liquid Chlorocuprates(I) W. W. PORTERFIELD
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Hampden-Sydney College, Hampden-Sydney, Va. 23943 J. T. YOKE Oregon State University, Corvallis, Ore. 97331
A liquid with the composition of the presumed compound triethylammonium dichlorocuprate(I) is prepared by mixing stoichometric amounts of the solid precursors CuCl and Et NHCl; similar liquids can be prepared using other tertiary amine and phosphine hydrochlorides. Spectroscopic and electrochemical studies indicate that the liquid nature of the systems is attributable to the presence of multiple chlorocuprate(I) species through chloride donor-acceptor equilibria. Two applications that utilize the liquid property of the compounds are: (a) use as a solvent for transition -metal chlorides in examining the effect of drastically lowered temperatures on the stoichiometry and coordination geometry of the chlorometallate complexes previously observed in molten LiCl/KCl and AlCl , and (b) construction of a voltaic cell in which the liquid chlorocuprate(I) serves as solvent and as both electroactive species. 3
3
T n studies of c o p p e r ( I ) c o o r d i n a t i o n a b o u t 12 years ago ( 1 ) , Y o k e a n d A
c o - w o r k e r s o b s e r v e d that the c r y s t a l l i n e solids c o p p e r ( I ) c h l o r i d e a n d
t r i e t h y l a m m o n i u m c h l o r i d e react q u i c k l y w h e n b r o u g h t i n t o contact to p r o d u c e a l i g h t green o i l . T h e o i l is q u i t e o x y g e n sensitive, a n d i t w a s a s s u m e d that the c o m p o u n d
triethylammonium dichlorocuprate ( I ) had
b e e n f o r m e d w h i c h was l i q u i d b e c a u s e of the l o w l a t t i c e e n e r g y i n h e r e n t to t h e b u l k y c a t i o n . M a n y p r e v i o u s p r e p a r a t i o n s of p o l y a l k y l a m m o n i u m c h l o r o c u p r a t e s ( 2 , 3, 4, 5 ) , h o w e v e r , h a d y i e l d e d o n l y c r y s t a l l i n e solids. C o n s e q u e n t l y , the u n u s u a l l i q u i d n a t u r e of the system i n s p i r e d s t r u c t u r a l studies a n d the synthesis of c o m p a r a b l e
compounds.
104 In Inorganic Compounds with Unusual Properties; King, R.; Advances in Chemistry; American Chemical Society: Washington, DC, 1976.
10.
PORTERFiELD
105
Liquid Chlorocuprates(I)
A N D YOKE
Experimental A l l c h l o r o c u p r a t e syntheses w e r e c a r r i e d o u t i n S c h l e n k g l a s s w a r e , a n d 1 0 - m m b o r o s i l i c a t e glass cuvettes w e r e a d a p t e d to S c h l e n k use i n o r d e r to a v o i d o x i d a t i o n d u r i n g f i l l i n g . T h e c e l l d e s i g n ( F i g u r e 4 ) w a s also a d a p t e d f o r d i r e c t filling f r o m t h e S c h l e n k a p p a r a t u s . R a m a n s p e c t r a w e r e o b t a i n e d o n a C a r y 82 i n s t r u m e n t at O r e g o n State U n i v e r s i t y a n d o n a J a r r e l l - A s h i n s t r u m e n t at the U n i v e r s i t y of N o r t h C a r o l i n a . V i s i b l e r a n g e spectra ( 14,000-26,000 c m " ) w e r e r e c o r d e d o n a B a u s c h a n d L o m b 505 s p e c t r o p h o t o m e t e r . 1
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Synthesis and Structural
Studies
R e a c t i o n 1 is the synthesis r e a c t i o n a n d R e a c t i o n s 2, 3, a n d 4 are the c h l o r i d e - t r a n s f e r e q u i l i b r i a t h a t are i n v o l v e d i n the f o r m a t i o n of t r i e t h y l ammonium dichlorocuprate(I).
B e c a u s e of t h e s e n s i t i v i t y of the l i q u i d
to o x i d a t i o n , a l l operations are c a r r i e d out i n S c h l e n k w a r e . T h e synthesis is effected s i m p l y b y m i x i n g s t o i c h i o m e t r i c q u a n t i t i e s of the t w o solids w h i c h r e a c t e n d o t h e r m i c a l l y to f o r m the l i q u i d i n a b o u t t w o m i n u t e s . Et NHCl 3
CuCl - + 2
+
C u C l -> E t N H C u C l s
C u C l +± C u C l 2
2 C u C l - *± C u C l 2
CuCl 2
2
+
(1)
2
3
+
C l -
