Polyatomic Zintl Anions Stabilized Through Crypt ... - ACS Publications

6 Polyatomic Zintl Anions Stabilized Through Crypt Complexation of the Cation Heteroatomic Examples 1

JOHN D. CORBETT, SUSAN C. CRITCHLOW, and ROBERT C. BURNS

Downloaded by UNIV LAVAL on July 12, 2016 | http://pubs.acs.org Publication Date: September 30, 1983 | doi: 10.1021/bk-1983-0232.ch006

Ames Laboratory-Department of Energy and Iowa State University, Department of Chemistry, Ames, IA 50011

A summary is given of the structures for the known homopolyatomic anions of the representative ele ments from groups IV and V and for a variety of heteropolyatomic examples. Also considered are factors important in their stabilization, elec tronic requirements, isoelectronic analogs, and new results for Sb 3-, Sb 2-, Pb Sb 2- and the unusual 1∞[KSn 3-]. The contributions of Ralph Rudolph to the study of these anions in solution are noted. 7

4

2

2

9

The f i r s t evidence that p o s t - t r a n s i t i o n elements, the metals e s p e c i a l l y , could be reduced to h i g h l y colored anions was published over 90 years ago by Joannis (1) who discovered that sodium and lead or t h e i r a l l o y s d i s s o l v e i n l i q u i d ammonia to y i e l d an i n t e n s e l y green-colored s o l u t e , A stoichiometry of 2,25 lead atoms per sodium (2) f o r what was e v i d e n t l y an anion l e d Kraus (3) to formulate t h i s as Pbg *". U n t i l the past decade the p r i n c i p a l information regarding t h i s and many other species were the s t o i c h i o m e t r i e s obtained by Z i n t l and coworkers (4>.5>6) from both potentiometric t i t r a t i o n s of the ammonia s o l u t i o n s and exhaustive e x t r a c t i o n of a l l o y s followed by a n a l y s i s . Among those so i d e n t i f i e d were Sn^"", Pb ^*", S b ^ 3 - and Bi ". But they found that s t r u c t u r a l studies were pre cluded by the c h a r a c t e r i s t i c decomposition of the amorphous s o l i d s i s o l a t e d from s o l u t i o n i n t o i n t e r m e t a l l i c phases and, at times, the heavy element, e.g., 1

7>9

?

3

3

>

5

>

7

(Na(NH )+) Sb^~ — • 3

3

NaSb(s) + 2NaSb (s) + 3nNH (g) 3

3

Current address: McMaster University, Department of Chemistry, Hamilton, Ontario L8S 4M1, Canada

0097-6156/83/0232-0095 $06.00/0 © 1983 American Chemical Society

Cowley; Rings, Clusters, and Polymers of the Main Group Elements ACS Symposium Series; American Chemical Society: Washington, DC, 1983.

96

RINGS, C L U S T E R S , A N D P O L Y M E R S

The i s o l a t i o n o f a few i n t e r e s t i n g and p r e s u m a b l y r e l a t e d compounds f r o m s i m i l a r e t h y l e n e d i a m i n e ( e n ) s o l u t i o n s has b e e n d e s c r i b e d more r e c e n t l y ( 7 , 8 ) , e.g., N a ^ S n g ^ e n and N a S b 4 e n plus a Na^Geg^en of marginal s t a b i l i t y . An i n c o m p l e t e s t r u c t u r a l study of the f i r s t r e v e a l e d a d i s t o r t e d S n p o l y h e d r o n w i t h l a r g e t h e r m a l e l l i p s o i d s f o r two t i n atoms, some r e s i d u a l Na-Sn i n t e r a c t i o n s , and s u b s t a n t i a l d i s o r d e r o f t h e en w h i c h a p p a r e n t l y complexed the sodium. I t was t h e r e c o g n i t i o n ( 9 ) t h a t 2 , 2 , 2 - c r y p t ( c p , T ) w o u l d be e

3

7


g

I a much more e f f e c t i v e way t o s e q u e s t e r t h e s o d i u m o r p o t a s s i u m c a t i o n s and t o p r e v e n t r e v e r s i o n t o c o n v e n t i o n a l p h a s e s t h a t has l e d t o t h e i s o l a t i o n o f t h e l a r g e number o f s t a b l e compounds o f the p o l y a n i o n s w h i c h a r e t o be c o n s i d e r e d h e r e i n . Typical s y n t h e s i s r e a c t i o n s may be r e l a t i v e l y f a s t and s i m p l e , e . g . , NaSn

2 e 2 5

( a l l o y ) + 2,2,2-crypt ^

s x a E

+

+

(cp-Na ) Sn 4

4 9

~

Homopolyatomic Anions The h o m o p o l y a t o m i c o r Z i n t l a n i o n s i n c o r p o r a t i n g p o s t - t r a n s i t i o n s e l e m e n t s o f g r o u p s IV and V w h i c h have been so s y n t h e s i z e d and s t r u c t u r a l l y c h a r a c t e r i z e d a r e l i s t e d i n T a b l e I , t o g e t h e r w i t h t h e i r o b s e r v e d s y m m e t r i e s and o t h e r i o n s o r m o l e c u l e s w i t h which they are i s o e l e c t r o n i c . As a m a t t e r o f f a c t o n l y t h r e e o f t h o s e g i v e n , Sng "", S b ~ and B i ^ " , were o b s e r v e d i n the e a r l i e r s o l u t i o n s s t u d i e s ( 6 ) , the l a s t c o r r e s p o n d i n g t o an a n a l y s i s o f 1.95 B i atoms p e r c h a r g e w h i c h t h e y a t t r i b u t e d t o " B i y " ( 1 5 ) . A l l o f the i o n s l i s t e d a p p e a r t o r e q u i r e c r y p t o r e q u i v a l e n t complexation of the a l k a l i metal c a t i o n s to prevent the a f o r e - m e n t i o n e d d e c o m p o s i t i o n . A l t h o u g h r e p l a c e m e n t o f t h e a l k a l i m e t a l c a t i o n by a n o n m e t a l l i c one w o u l d p r e s u m a b l y o b v i a t e the r e q u i r e m e n t o f a w e l l - c o m p l e x e d m e t a l c a t i o n , t h e compound (NMe ) Sng was r e c e n t l y f o u n d t o decompose s l o w l y a t room temperature to v a r i o u s methyl stannanes ( 1 8 ) , w h i l e the i n t r o d u c t i o n o f Φ^Ρ"" o r (^As* t o Sng^" s o l u t i o n s i n en a l s o c a u s e s d e c o m p o s i t i o n ( 8 ) . Of c o u r s e , many p o l y p h o s p h i d e s and a t l e a s t some p o l y a r s e n i d e s a r e known t o be s t a b l e w i t h o u t s e q u e s t e r i n g the c a t i o n ( 1 9 ) and t h e same a p p e a r s t o be g e n e r a l l y t r u e o f 4

3

2

?

3 -

t+

i+

1


6.

CORBETT E T A L .

97

Polyatomic Zintl Anions

Table I H o m o p o l y a t o m i c A n i o n s o f Known S t r u c t u r e From Groups IV and V—

Anion

Symmetry

Ge\~ C

D

2v

η Avje^ C


Gel"

4v

Characteristics 1 ^

J

+

Bi5 (D

3 h

) 11

lavender chunks

D

~ 3h"

+

C

4v

Bi5 (D

Sn|~

D

3h

orange-brown

D

3h

ruby red prisms

D

4h

dark red

dark red rods

-

Str. Ref

10

dark red rods

Sn£-

Sbf

Isoelectronic Analogs

3 h

)

12 13

plates

w J

13 14

plates V Se^ ,Te^

dark green prisms or p l a t e s A

s

~

i l

D C

3

3v

+

i C r y p t - K or crypt-Na -^Partially disordered

+

15

deep red rods

P

brown prisms, rods

P

16

ll 7

P

S

>43

salts

p o l y c h a l c o g e n i d e a n i o n s , so b o t h g r o u p s a r e e x c l u d e d f r o m t h e present c o n s i d e r a t i o n . The o c c u r r e n c e o f many i s o e l e c t r o n i c and o f t e n i s o s t r u c t u r a l analogs of these anions i n Table I i s r e a s s u r i n g . These a r e f o u n d p r i n c i p a l l y among h o m o p o l y a t o m i c c a t i o n s and e l e c t r o n i c a l l y r e l a t e d p o l y b o r a n e s , f o r which t h e i n t e r r e l a t i o n s h i p s have been p r e v i o u s l y d i s c u s s e d ( 2 0 ) . The c o n t r a s t i n e x p e r i m e n t a l c o n d i t i o n s n e c e s s a r y t o s t a b i l i z e t h e two t y p e s o f p o l y a t o m i c ions i s worth emphasizing. The n a t u r e o f t h e c o u n t e r i o n and t h e s o l v e n t , i f a n y , a r e c r i t i c a l t o b o t h . The c a t i o n s r e q u i r e h i g h a c i d i t y - t h e a b s e n c e o f b a s i c m o l e c u l e s o r a n i o n s - and c a n g e n e r a l l y be o b t a i n e d f r o m a c i d i c h a l i d e and o t h e r m e l t s c o n t a i n i n g mainly A l C l ^ " , A 1 C 1 ~ , H f C l ^ ~ , e t c . anions ( s u p e r a c i d s a p p e a r u s e f u l i n an a n a l o g o u s way m a i n l y f o r t h e polychalcogenide cations). On t h e o t h e r h a n d , s y n t h e s i s o f t h e p o l y a n i o n s needs j u s t t h e o p p o s i t e , a good p o l a r s o l v e n t and a s t r o n g l y complexing l i g a n d f o r the c o u n t e r c a t i o n i n order to b l o c k e l e c t r o n t r a n s f e r f r o m t h e a n i o n and t h e r e b y t o d e s t a b i l i z e what a r e e v i d e n t l y s t r o n g i n t e r a c t i o n s and d e r e a l i z a t i o n e n c o u n t e r e d i n t h e dense s o l i d s t a t e . I n no i n s t a n c e h a s c o o r d i n a t i o n o f en ( o r N H ) t o a p o l y a n i o n been o b s e r v e d i n s p i t e o f t h e f a c t 2

7

6

3


98


t h a t e a c h atom i n t h e s e i o n s has o n l y t h r e e t o f i v e n e a r e s t neighbors. A c c o r d i n g to e a r l i e r c o n c l u s i o n s (summarized i n 2 0 ) , t h i s must r e s u l t f r o m t h e p r e s e n c e o f a s m a l l o r b i t a l b a s i s s e t s u b s t a n t i a l l y ρ o r b i t a l s o n l y - which i s important to the s t a b i l i t y o f t h e s e p o l y a t o m i c s p e c i e s , a n i o n s as w e l l as c a t i o n s . On t h e o t h e r hand a b a s i c f u n c t i o n a l i t y i s p r o b a b l y p r e s e n t i n some, f o r example a t t h e open s q u a r e b a s e o f Sng *"". T h e r e a r e no p a r t i c u l a r s u r p r i s e s r e g a r d i n g t h e g e o m e t r y o f any o f t h e Z i n t l i o n s t a b u l a t e d a l t h o u g h some o f t h e s e had p r e v i o u s l y been r e p r e s e n t e d o n l y by compounds o f n o n m e t a l s . The a n i o n s i n (cp-Na+) ^Sug "" and a r e c e n t r e s u l t f o r ( c p - K ) S b ~ « 2 e n a r e shown i n F i g u r e 1. The c o n f i g u r a t i o n s o f a l l o f t h e a n i o n s a r e i n a c c o r d w i t h Wade's r u l e s , Ge^" and S n g " r e p r e s e n t i n g t h e f i r s t e x a m p l e s o f C^v g e o m e t r y p r e d i c t e d for a 2 2 - e l e c t r o n , nine-atom nido s p e c i e s . I n s t e a d , the s u r p r i s e i s f o u n d w i t h t h e s u b s t a n t i a l l y D h symmetry o f t h e i s o e l e c tronic B i , a r e s u l t w h i c h may be r e l a t e d t o t h e a c i d i c , i o n i c environment n e c e s s a r y f o r the s t a b i l i t y of t h i s a p o l a r c a t i o n , i n c o n t r a s t to the u s u a l d i p o l a r s o l v e n t s w h i c h would s t a b i l i z e the p o l a r Sng**"", e t c . An a p p r e c i a b l e e l o n g a t i o n o f t h e t r i g o n a l prism i n B i r e l a t i v e t o Ge ~" and B H " may be a r e f l e c t i o n o f t h e a c c o m m o d a t i o n o f an a d d i t i o n a l p a i r o f e l e c t r o n s i n an a p p r o x i m a t e l y n o n - b o n d i n g o r b i t a l ( 2 1 , 2 2 ) , a change w h i c h g i v e s t h e c a t i o n a l o w e r and more r e a s o n a b l e c h a r g e . A c c o r d i n g t o CNDO c a l c u l a t i o n s ( 1 0 , 1 2 ) the i s o l a t e d G e g " and Sng *" i o n s show v e r y l i t t l e (< 0.5 eV) dependence o f t h e a t o m i z a t i o n e n e r g y on c o n f i g u r a t i o n b e t w e e n t h e o b s e r v e d C^v and t h e h y p o t h e t i c a l D h l i m i t , a r e s u l t which l e d to a p r e d i c t i o n of t h e i r f l u c t i o n a l i t y in solution. 1

4

+

3

3

7


4

3

5

+

g

5

+

2

g

2

g

g

g

4

1

3

R a l p h R u d o l p h made i m p o r t a n t c o n t r i b u t i o n s t o t h e q u e s t i o n o f f l u c t i o n a l i t y , and he p r o v i d e d v i r t u a l l y t h e o n l y modern i n f o r m a t i o n on t h e s o l u t i o n s o f t h e Z i n t l i o n s . Unfortunately t h e p u b l i c a t i o n s a r e a t p r e s e n t l i m i t e d to two c o m m u n i c a t i o n s ( 2 3 , 2 4 ) , one c o n f e r e n c e p r o c e e d i n g s ( 2 5 ) , and a b r i e f n o t e on e l e c t r o c h e m i c a l g e n e r a t i o n of nine-atom s p e c i e s ( 2 6 ) . Fluctiona l i t y o f Sng *" was e s t a b l i s h e d by t h e o b s e r v a t i o n o f a s i n g l e NMR t r a n s i t i o n s p l i t by i n t r a m o l e c u l a r c o u p l i n g b e t w e e n Sn and Sn. A single 'Pb r e s o n a n c e f o r Pbg *" and t i n and l e a d r e s o n a n c e s f o r a l l p o s s i b l e Sng-xPbx**" s p e c i e s were o b s e r v e d when a m i x e d a l l o y was e x t r a c t e d w i t h en ( w i t h o u t c r y p t ) . The Sng-xGex "" f a m i l y was a l s o i n f e r r e d f r o m t i n s p e c t r a . An important o b s e r v a t i o n , c o n s i s t e n t w i t h our s y n t h e t i c e x p e r i e n c e s , was t h a t i n t e r a n i o n i c e q u i l i b r i u m i n s o l u t i o n i s v e r y s l o w and these r e a c t i o n s occur p r i n c i p a l l y at the s u r f a c e of the s o l i d a l l o y phases. 1

1 1 9

1 1 7

2 0

1

4

1 1 9

R u d o l p h and h i s c o w o r k e r s a l s o r e p o r t e d o b s e r v a t i o n by Sn and S n NMR o f what was i n t e r p r e t e d t o be a n o v e l , f l u c t i o n a l t e t r a h e d r a l S n ^ " s p e c i e s when t h e y u s e d Na-Sn a l l o y s p o o r e r i n t i n , comparable to those used i n the p r e p a r a t i o n of the h i g h l y insoluble (cp-Na ) Sn ~. A diamagnetic " t e t r a h e d r a l " species 1 1 7

2

+

2

2

5




CORBETT E T A L .

4

Figure 1. Structures of two homopolyatomic anions. Key: top, Sn from cryptNa salt at 5° [σ(ά) = 0.004 to 0.005 A] (\2); and bottom, Sb ~/from crypt-K salt at -80° [σ(ά) = 0.002 À] (14). 9

+

3

7


+

100


was i n t e r p r e t e d t h e o r e t i c a l l y i n t e r m s o f a d y n a m i c J a h n - T e l l e r d i s t o r t i o n of the 1 8 - e l e c t r o n a n i o n ( 2 7 ) . A more-or-less t e t r a h e d r a l b u t b a d l y d i s o r d e r e d G e ~ w h i c h i s p r e s u m a b l y s i m i l a r has b e e n s t u d i e d s t r u c t u r a l l y ( 2 8 ) , b u t t h e compound once t h o u g h t t o c o n t a i n t h e a n a l o g o u s S n ^ " i s now known t o be a s a l t o f S n B i ~ (29). An o b v i o u s a b s e n t e e f r o m t h e summary i n T a b l e I i s P b g " , t h e f i r s t p o l y m e t a l a n i o n d i s c o v e r e d . Many e x p e r i m e n t s i n v o l v i n g Na-Pb and K-Pb r e a c t i o n s w i t h c r y p t o r i t s benzo d e r i v a t i v e e i t h e r i n en o r NH have o n l y g i v e n t h e P b " " s a l t s o r a l l o y s as s o l i d phases. The i n t e r m e d i a t e s P b ^ " " and B i " r e p o r t e d by Z i n t l l i k e w i s e have n o t been i s o l a t e d , as w e l l as t h e S b ~ and B i " " i o n s w h i c h w o u l d be s u b s t a n t i a l l y more r e d u c e d t h a n any s p e c i e s o b t a i n e d so f a r f r o m s o l u t i o n . 2

4

2

2

2

2

4

2

3

5

3

5

3

3

3


3

Electronic

Requirements

The l a c k o f h o m o p o l y a t o m i c a n i o n s f o r e l e m e n t s t o t h e l e f t o f g r o u p IV i n T a b l e I i s n o t e w o r t h y . Z i n t l r e p o r t e d no s u c c e s s w i t h r e a c t i o n s o f a l k a l i m e t a l a l l o y s o f t h e c o p p e r and z i n c f a m i l y e l e m e n t s and o f t h a l l i u m w i t h l i q u i d ammonia, and t h e g e n e r a l l y s t a b i l i z i n g e f f e c t o f c r y p t has n o t been e v i d e n t i n o u r own i n v e s t i g a t i o n s o f a l l o y s o f m e r c u r y and t h a l l i u m . On t h e o t h e r hand, i t i s p o s s i b l e t o i s o l a t e a w h i t e c r y p t - p o t a s s i u m g o l d compound f r o m ammonia s o l u t i o n s a t l o w t e m p e r a t u r e s w h i c h decomposes t o e l e m e n t a l g o l d (+?) above about -10°C ( 3 0 ) . A l t h o u g h t h e p s e u d o h a l i d e Au~" seems a l i k e l y c a n d i d a t e i n t h e w h i t e s o l i d , t h e d e c o m p o s i t i o n seems u n u s u a l c o n s i d e r i n g t h e h i g h s t a b i l i t i e s o f KAu and t h e s e m i c o n d u c t i n g CsAu ( d i s c u s s e d i n 31), u n l e s s the decomposition r e a c t i o n a c t u a l l y i n v o l v e s reduc t i o n of the l i g a n d . The a p p a r e n t i n s t a b i l i t y o f h o m o p o l y a t o m i c a n i o n s o f e l e ments t o t h e l e f t o f g r o u p IV (and o f p o l y a t o m i c c a t i o n s t o t h e l e f t o f g r o u p V) i s t h o u g h t t o r e s u l t f r o m a d e f i c i e n c y o f b o n d i n g e l e c t r o n s i n s p e c i e s where t h e p r i n c i p a l b o n d i n g i s c o n s i d e r e d to o r i g i n a t e l a r g e l y from p-type o r b i t a l s . The e l e c t r o n d e f i c i e n t p o l y b o r a n e s , B H " , w i t h w h i c h t h e s e c l u s t e r s have some s i m i l a r i t i e s i n b o n d i n g ( 3 2 ) , c o n t a i n 2.17 t o 2.4 pe l e c t r o n s p e r b o r o n atom f o r η b e t w e e n 12 and 5, r e s p e c t i v e l y , and s i m i l a r r e q u i r e m e n t s a p p l y t o t h e h o m o p o l y a t o m i c a n i o n s o f germanium, t i n and l e a d as w e l l . The p - e l e c t r o n c o u n t p e r s k e l e t a l atom (e/M) shown i n F i g u r e 2 f o r most o f t h e s t r u c t u r a l l y known p o l y a n i o n s and c a t i o n s o f t h e f o u r t h , f i f t h and s i x t h p e r i o d s r e v e a l t h a t a r e l a t i v e l y c l e a r minimum o f about 2.2 e l e c t r o n s p e r atom i s n e c e s s a r y f o r s t a b i l i t y i n a l l , i n s p i t e o f an e x p e c t a t i o n of weaker bonding f o r the h e a v i e r e l e m e n t s . A l l c l u s t e r and cage i o n s t o t h e r i g h t o f 3e/M i n t h e F i g u r e c a n be f u r t h e r d e s c r i b e d as c o n t a i n i n g ~2.2 - 3.0 s k e l e t a l b o n d i n g e l e c t r o n s p e r atom, w i t h t h e r e m a i n i n g number r e l e g a t e d t o t h e n o n bonding lone p a i r s which are m a i n l y important i n d e t e r m i n i n g the 2

n

n


6.

CORBETT ET A L .

B

2h


101


n n H

η = Ι2

Ge|"

n=5

Ge*

As*'

Se^ Se

S e

2

+

2+ 8

43

.

Sn TI 3

8

/ ' S n

25

Pb§" ,S°Bi| ΒΙΓ

1.5

2.0

Te

6

S b

% T

S n

+

,

2

2 T e

B i

6

7~

· ·2-

R1

Β

4

3.0 ρ

4

|"

a 2+ 8

2.5

|-

Te T e

3.5

electrons/M

Figure 2. Number of skeletal ρ electrons per atom in cluster anions (Π) and cations (·) as a function of period (33).


4.0

102


shape of the c l u s t e r (30). Many polychalcogenide anions with >4e/M are a l s o i n t h i s category. Heteropolyatomic

Anions


A rather obvious means of i n c o r p o r a t i n g the e l e c t r o n - p o o r e r elements from groups e a r l i e r i n the p e r i o d i c table i n t o c l u s t e r s i s then to combine them with e l e c t r o n - r i c h e r elements. Some r e s u l t s of s y n t h e t i c and s t r u c t u r a l i n v e s t i g a t i o n s of t h i s sort i n v o l v i n g ions with 2.2 - 3e per c l u s t e r element are l i s t e d i n Table I I together with data f o r three e l e c t r o n - r i c h e r mixed c l u s ter anions.

Some Heteroatomic Anion

Symmetry

Sn BÎ2

~ T

2

2

Pb sb 2

Tl Te 2

2 2

~

C

p electrons

C

Str. Ref.

Compare

V

sb

4

-}

d

2v

12

2>3h-)

20

3

TISng "

Anions

29

d

~ T

2

Table I I Examples of Polyatomic

14

-

30

j

Ge 29

TlSn

3 9

~

C

22

D

4v( 4 / 2 > ^2* y P ~ ^ " c a t i o n s f i l l the remainder of the c e l l (R = 0.075, R = 0.090 f o r data to 2Θ = 45°) (37). The independent anion u n i t shown i n Figure 5 contains two s u r p r i s e s . F i r s t , the potassium atoms have four t i n neighbors at 3.55 to 3.74 Â through b r i d g i n g opposite edges on the waist of the Sng u n i t , with two more t i n atoms at greater d i s t a n c e s of 4.11 or 4.22 Â to produce a d i s t o r t e d t r i g o n a l a n t i p r i s m of t i n about each potassium. There i s no evidence (± 0.5e/A" ) f o r en groups coordinated to e i t h e r of the potassium atoms. Second, the d i s t a n c e s i n the S n g " group are s c a r c e l y a l t e r e d by the presence of the two potassium atoms, as can be as seen by comparison of these r e s u l t s with those f o r the 'naked Sng *" shown i n Figure 1. Judging from K^Sn^ where potassium has 6 to 8 t i n neighbors i n the range 3.70 to 3.85 Â (maximum d e v i a t i o n = 0.03 to 0.05 Â) (39), the potassium-tin i n t e r a c t i o n s found here appear normal except f o r the short p a i r at 3.55 Â about K(4). Within the S n p o r t i o n of the s t r u c t u r e , the s i m i l a r Sn-Sn d i s t a n c e s i n a l l but the square capped face average 2.964 (5) Â i n t h i s compound com pared with 2.966 (6) Â i n Sng ". The s t r u c t u r a l data were c o l l e c t e d at -100 and 5°, r e s p e c t i v e l y , so that some expansion of the c l u s t e r i n K S n " would probably be seen i n an isothermal compari son. In a d d i t i o n , there appears to be a p e r c e p t i b l e d i s t o r t i o n of the c l u s t e r i n the new potassium s a l t i n that Sn-Sn d i s t a n c e s where both atoms have potassium neighbors are longer by an average of 0.027 Â. Although the charge t r a n s f e r to potassium i s seem i n g l y not l a r g e enough to a l t e r the t i n c l u s t e r very much, perhaps i t i s enough to e l i m i n a t e the ( r e l a t i v e l y weak) tendency f o r potassium to coordinate en. The packing of the crypt-K"*" c a t i o n s can not be a s i g n i f i c a n t f a c t o r i n preventing a l l c o o r d i n a t i o n of solvent s i n c e the s h o r t e s t d i s t a n c e between these potassium atoms and the nearest l i g h t atom i n crypt i s 4.27 Â. With these unusual circumstances i t i s somewhat r e a s s u r i n g to f i n d another example of a s s o c i a t i o n of a c l u s t e r with an a l k a l i metal c a t i o n . In R b A s 3 e n the rubidium atoms a l l bridge edges of the anion, with the solvent coordinated to the a l k a l i metal only on the outside of the R b A s 'complex' (40). +

3

3

g

g

1

l

1

S

i

x

c r

t

1

2


w

3

4

1

1

g

14

3

g

e

3

7

3

7

Acknowledgment T h i s research was supported by the O f f i c e of B a s i c Energy Sciences, M a t e r i a l s Sciences D i v i s i o n . The Ames Laboratory i s operated f o r the U. S. Department of Energy by Iowa State U n i v e r s i t y under c o n t r a c t No. W-7405-Eng-82.


RINGS, CLUSTERS, AND POLYMERS


108



6.

CORBETT ET A L .


109

Literature Cited 1. Joannis, A. C. R. Hebd. Seances Acad. Sci. 1891, 113, 745; 1892, 114, 587. 2. Smyth, F. H. J. Am. Chem. Soc. 1917, 39, 1299. 3. Kraus, C. A. J. Am. Electrochem. Soc. 1924, 45, 175. 4. Zintl, E.; Goubeau, J; Dullenkopf, W. Z. Phys. Chem., Abt. A 1931, 154, 1. 5. Zintl, E.; Harder, A. Z. Phys. Chem., Abt. A 1931, 154, 47. 6. Zintl, E.; Dullenkopf, W. Z. Phys. Chem., Abt. Β 1932, 16, 183. 7. Kummer, D.; Diehl, L. Angew. Chem., Int. Ed. Engl. 1970, 9, 895. 8. Diehl, L.; Khodadedeh, K.; Kummer, D.; Strahle, J. Chem. Ber. 1976, 109, 3404. 9. Corbett, J. D.; Adolphson, D. G.; Merryman, D. J.; Edwards, P. A.; Armatis, F. J . J . Am. Chem. Soc. 1975, 97, 6267. 10. Belin, C. Η. E.; Corbett, J. D.; Cisar, A. J. Am. Chem. Soc. 1977, 99, 7163. 11. Corbett, J. D.; Belin, C. Η. Ε., unpublished research. 12. Corbett, J. D.; Edwards, P. J . Am. Chem. Soc. 1977, 99, 3313. 13. Edwards, P.; Corbett, J. D. Inorg. Chem. 1977, 16, 903. 14. Critchlow, S. C.; Corbett, J. D., to be published. 15. Cisar, Α.; Corbett, J. D. Inorg. Chem. 1977, 16, 2482. 16. Belin, C. H. E. J . Am. Chem. Soc. 1980, 102, 6036. 17. Adolphson, D. G.; Corbett, J. D.; Merryman, D. J . J. Am. Chem. Soc. 1976, 98, 7234. 18. Teller, R. G.; Krause, L. J.; Haushalter, R. C. Inorg. Chem. 1983, 22, in press. 19. von Schnering, H.-G. Angew Chem., Int. Ed. Engl. 1981, 20, 33. 20. Corbett, J . D. Prog. Inorg. Chem. 1976, 21, 129. 21. King, R. B. 1981, private communication. 22. Burns, R. C.; Gillespie, R. J.; Barnes, J . Α.; McGlinchey, M. J . Inorg. Chem. 1982, 21, 806. 23. Rudolph, R. W.; Wilson, W. L.; Parker, F.; Taylor, R. C.; Young, D. C. J. Am. Chem. Soc. 1978, 100, 4629. 24. Rudolph, R. W.; Wilson, W. L.; Taylor, R. C. J. Am. Chem. Soc. 1981, 103, 2480. 25. Rudolph, R. W.; Taylor, R. C.; Young, D. C. in "Fundamental Research in Homogeneous Catalysis", M. Tsutsui, Ed.; Plenum Press: New York, 1979, p. 997. 26. Pons, B. S.; Santure, D. J.; Taylor, R. C.; Rudolph, R. W. Electrochem. Acta 1981, 26, 365. 27. Rothman, M. J.; Bartell, L. S.; Lohr, L. L. J. Am. Chem. Soc. 1981, 103, 2482. 28. Critchlow, S. C.; Corbett, J. D. J . Chem. Soc., Chem. Commun. 1981, 236. 29. Critchlow, S. C.; Corbett, J. D. Inorg. Chem. 1982, 21, 3286.


110

30. 31. 32. 33. 34.


35. 36. 37. 38. 39. 40.


Burns, R. C.; Corbett, J . D. J. Am. Chem. Soc. 1981, 103, 2627. Hensel, F. Adv. Phys. 1979, 28, 589. Corbett, J . D. Inorg. Chem. 1968, 7, 198. Burns, R. C.; Corbett, J . D. J. Am. Chem. Soc. 1982, 104, 2804. Belin, C. H. E.; Charbonnel, M. M. Inorg. Chem. 1982, 21, 2504. Burns, R. C.; Corbett, J . D. Inorg. Chem. 1981, 20, 4433. Krebs, B.; Hinter, H.-V. Z. Anorg. Allg. Chem. 1980, 462, 143. Burns, R. C.; Corbett, J . D., to be published. Rudolph, R. W. 1980, private communication. Hewaidy, I. F.; Busmann, E.; Klemm, W. Z. Anorg. Allg. Chem. 1964, 328, 283. Honle, W.; von Schnering, H.-G. 1983, to be published.

RECEIVED

April 8, 1983


Polyatomic Zintl Anions Stabilized Through Crypt ... - ACS Publications

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