Synthesis and Study of Octa-aza Annulene Complexes With Unusual

30 Synthesis and Study of Octa-aza Annulene Complexes With Unusual Properties VIRGIL L. GOEDKEN and SHIE-MING PENG

Downloaded by UNIV OF BATH on July 3, 2016 | http://pubs.acs.org Publication Date: June 1, 1976 | doi: 10.1021/ba-1976-0150.ch030

University of Chicago, Chicago, Ill. 60637

Prototype complexes, [M(C H N )](ClO )2, derived from the metal template condensation of 2,3-butanedihydrazone and formaldehyde, undergo further ligand oxidation with various oxidants to form molecular complexes of type M(C H N ) containing completely conjugated 16π-electron systems. The nickel complex is an eclipsed cofacial dimer, [Ni(C H N )] , with a Ni-Ni bond length of 2.784(2) A. The dimers are stacked in the lattice with the Ni atoms forming a chain down the c crystal axis. The Co(III)-alkyl complexes have unusual NMR spectra with the proton reso nances of the macrocyclic ligand displaying abnormal upfield shifts while the axial ligand protons are observed downfield from their normal positions. The temperature dependence and solvent dependence, together with shifts on chemical alteration of the complex, indicate that the abnormal shifts may be attributed to a thermally populated paramagnetic state at ambient temperatures. 10

10

14

10

20

8

4

8

14

8

2

* T * h e s t u d y of s y n t h e t i c m a c r o c y c l i c l i g a n d complexes has c o n s i d e r a b l e A

m e r i t . I n g e n e r a l , these complexes

have a robust constitution a n d

are not easily d e s t r o y e d , not e v e n w h e n s u b j e c t e d to s t r o n g l y a c i d i c , basic, o x i d a t i v e , or r e d u c t i v e m e d i a . T h e s e aspects h a v e b e e n a d v o c a t e d a n d u t i l i z e d , p r i n c i p a l l y b y B u s c h , i n a l e n g t h y series of f a r r e a c h i n g investigations (see R e f e r e n c e 2).

R e f e r e n c e I a n d references c i t e d t h e r e i n , as w e l l as

T h i s p a p e r reports the synthesis of some b i s - a - d i i m i n e

m a c r o c y c l i c complexes a n d t h e i r c h e m i c a l t r a n s f o r m a t i o n to y i e l d a series of c o m p l e t e l y c o n j u g a t e d 1 6 ^ e l e c t r o n l i g a n d complexes.

A n u m b e r of

these c o m p l e x e s h a v e some u n c o m m o n p r o p e r t i e s w h i c h are d i s c u s s e d i n detail. 379 King; Inorganic Compounds with Unusual Properties Advances in Chemistry; American Chemical Society: Washington, DC, 1976.

380

INORGANIC

Our

initial objective was

COMPOUNDS

to synthesize

WITH

UNUSUAL

a completely

PROPERTIES

conjugated

l i g a n d system w h i c h , because of a b n o r m a l s h o r t e n i n g of the m e t a l - l i g a n d distances, m i g h t i n t e r a c t strongly e n o u g h w i t h the m e t a l to create plexes w i t h u n u s u a l c h e m i c a l a n d p h y s i c a l properties.

com-

It is w e l l k n o w n

t h a t a c o m p r e s s i o n of the electronic energy l e v e l occurs i n c o m p l e x e s of soft or p o l a r i z a b l e l i g a n d s s u c h as d i t h i o l e n e a n d d i t h i o l a t o - t y p e l i g a n d s (3).

B u s c h a n d co-workers also d e m o n s t r a t e d that the r e d o x potentials

of metals of m a c r o c y c l i c l i g a n d s d e p e n d strongly o n the degree a n d t y p e of c o n j u g a t i o n present i n the l i g a n d as w e l l as o n the r i n g size (4, 5 ) . T h e m a c r o c y c l i c l i g a n d system chosen for this s t u d y , M ( C i o H i N ) , 4

8

is that o b t a i n e d b y the m e t a l t e m p l a t e c o n d e n s a t i o n of 2 , 3 - b u t a n e d i h y d r a -


zone w i t h aldehydes, followed

b y four-electron

ligand oxidation.

The

s i m p l i c i t y of t h e syntheses a n d the i n e x p e n s i v e s t a r t i n g m a t e r i a l s m a k e the c o m p l e x e s a v a i l a b l e for a w i d e v a r i e t y of studies. A l t h o u g h the C u , N i , C o , a n d F e complexes of this l i g a n d h a v e b e e n p r e p a r e d , those of N i a n d C o a p p e a r to be most u n u s u a l a n d t h e y w i l l b e d i s c u s s e d i n greatest d e t a i l . Syntheses [ C u ( C H o N ) C l ( H 0 ) ] ( C l 0 4 ) . F o r m a l d e h y d e , 3.22 g ( 3 8 % i n a q u e o u s solution), was a d d e d to a s o l u t i o n c o n t a i n i n g 3.41 g C u C l · 2 H 0 i n 50 m l w a t e r . T h e n 4.56 g 2 , 3 - b u t a n e d i h y d r a z o n e ( p r e p a r e d b y the B u s c h a n d B a i l a r m e t h o d ; see Reference 6) was a d d e d as a s o l i d , a n d the s o l u t i o n w a s s t i r r e d 10 m i n . T h e s o l u t i o n t u r n e d d a r k green as the r e a c t i o n p r o c e e d e d . A n a q u e o u s s o l u t i o n of 5 g N a C 1 0 a n d 0.1 m l H C 1 0 w a s a d d e d to p r e c i p i t a t e the c o m p l e x w h i c h separates as s h i n y green plates. T h e c o m p l e x w a s filtered, w a s h e d w i t h w a t e r , a n d t h e n d r i e d i n the a i r . [ N i ( C H o N ) ] ( C l 0 ) . F o r m a l d e h y d e , 1.61 g ( 3 8 % i n w a t e r ) , w a s a d d e d to a s o l u t i o n c o n t a i n i n g 3.65 g N i ( C 1 0 ) · 6 H 0 i n 30 m l C H C N . T o this b l u e s o l u t i o n , 2.28 g 2 , 3 - b u t a n e d i h y d r a z o n e w a s a d d e d . T h e m i x t u r e was a l l o w e d to s t a n d 2 h r ; t h e n 50 m l d i e t h y l ether w a s a d d e d to i n d u c e p r e c i p i t a t i o n of the p r o d u c t . T h e b r o w n p r o d u c t w a s filtered, a n d t h e n r e c r y s t a l l i z e d f r o m a c e t o n i t r i l e . [ C o ( C H N ) ] ( C 1 0 ) . T h e p r o c e d u r e is the same as for the n i c k e l c o m p l e x , b u t the reactions m u s t be c a r r i e d out u n d e r a n inert atmosphere. [ F e ( C H o N ) ( C H C N ) ] ( C l 0 ) . A s o l u t i o n c o n t a i n i n g 3.22 g 3 8 % f o r m a l d e h y d e ( i n w a t e r ) a n d 3.44 g 2,3-butanedione w a s a d d e d to a s o l u t i o n of 7.27 g F e ( C 1 0 ) · 6 H 0 i n 100 m l C H C N . T h e n 2.6 g a n h y d r o u s h y d r a z i n e w a s a d d e d d r o p w i s e , a n d the r e d s o l u t i o n w a s filtered to r e m o v e i n s o l u b l e residues. T h e solution w a s t h e n s t o p p e r e d a n d r e f r i g e r a t e d 12 h r d u r i n g w h i c h t i m e the p r o d u c t c r y s t a l l i z e d . T h e p r o d u c t w a s filtered, w a s h e d w i t h e t h a n o l , a n d t h e n a i r d r i e d . [ C u ( C i H i N ) ] . A s o l u t i o n of 200 m g [ C u ( C i H N ) C l ( H O ) ] ( C 1 0 ) a n d 1 m l t r i e t h y l a m i n e w a s p r e p a r e d i n 10 m l a c e t o n i t r i l e . M o l e c u l a r o x y g e n w a s t h e n b u b b l e d t h r o u g h the s o l u t i o n 5 m i n . T h e p r o d u c t , 1 0

2

8

2

2

2

4

1 0

2

8

4

4

2

4

2

3

1 0

2 0

1 0

2

8

4

8

2

3

2

4

0

4

8

4

2

2

2

3

0

2 0

8

4

King; Inorganic Compounds with Unusual Properties Advances in Chemistry; American Chemical Society: Washington, DC, 1976.

2

30.

GOEDKEN

AND

Octa-aza

PENG

Annulene

381

Complexes

w h i c h p r e c i p i t a t e s as lustrous flaky green crystals, w a s filtered, w i t h C H C N , a n d t h e n d r i e d in vacuo ( y i e l d about 3 0 % ).

washed

3

[ N i ( C H N ) ] 2 . A s o l u t i o n of 200 m g [ N i ( C H o N ) ] ( C 1 0 ) i n 30 m l C H C N w a s p r e p a r e d , a n d 0.5 m l p y r i d i n e w a s a d d e d . M o l e c u l a r o x y g e n w a s t h e n b u b b l e d t h r o u g h the s o l u t i o n 10 m i n . A lustrous, b l a c k , finely d i v i d e d p r e c i p i t a t e f o r m e d , w h i c h w a s filtered, w a s h e d w i t h C H C N , a n d t h e n d r i e d in vacuo. N o t e : the d e s i r e d p r o d u c t reacts s l o w l y w i t h m o r e m o l e c u l a r oxygen, g o i n g b a c k i n t o s o l u t i o n to give a n intense green s o l u t i o n w h i c h w e w e r e u n a b l e to isolate a n d c h a r a c t e r i z e . I n o r d e r to a v o i d this difficulty, other oxidants m a y be u s e d w i t h e q u a l f a c i l i t y . F o u r e q u i v a l e n t s of either I or [ F e ( a c a c ) ] , acac = a c e t y l acetonato l i g a n d , d i s s o l v e d i n C H C N m a y be u s e d as a n o x i d a n t i n p l a c e of m o l e c u l a r oxygen. Y i e l d s of the [ N i ( C H i N ) ] d i m e r a p p r o a c h 3 0 % . O t h e r oxidants, s u c h as o - c h l o r a n i l or 2,3-dichloro-5,6d i c y a n o 1,4-benzoquinone, are c a p a b l e of i n t r o d u c i n g d o u b l e b o n d s i n t o the m a c r o c y c l i c l i g a n d , b u t the p r o d u c t s are charge transfer adducts that c o n t a i n some f o r m of the oxidant. 1 0

1 4

1 0

8

2

8

4

2

3

8

2

3

3


1 0

4

8

2

[ C o ( C i o H N s ) ( C H N ) ] I . A 5 - m l s o l u t i o n c o n t a i n i n g 1.0 g I i n C H C N was a d d e d to a s o l u t i o n of 200 m g [ C o ( C H N ) ( C H C N ) ] (C10 ) a n d 0.5 m l p y r i d i n e d i s s o l v e d i n 15 m l C H C N . T h e b l a c k , c r y s t a l l i n e p r o d u c t precipitates w i t h i n a f e w m i n u t e s of m i x i n g the reagents. T h e p r o d u c t was filtered, w a s h e d w i t h C H C N , a n d t h e n d r i e d in vacuo. 1 4

r >

r >

2

3

2

3

1 0

4

2

2 0

8

3

2

8

3

[ C o ( C i H i N ) ( a x i a l base) ( R ) ] . I n these c o m p o u n d s base = p y r i d i n e , 3 - p i c o l i n e , 4 - p i c o l i n e , a c e t o n i t r i l e , or m e t h y l h y d r a z i n e a n d R = - C H , - C H C H , or - C H r , . T h e s e o r g a n o - C o ( I I I ) c o m p l e x e s w e r e p r e p a r e d u s i n g a g e n e r a l scheme p r e v i o u s l y r e p o r t e d i n w h i c h a n o r g a n i h y d r a z i n e undergoes o x i d a t i v e d e a m i n a t i o n w i t h the o r g a n o - f r a g m e n t b e i n g transferred to the c o b a l t c o m p l e x ( 7 ) . U n d e r the m o r e b a s i c c o n d i t i o n s u s e d here, l i g a n d o x i d a t i o n also occurs, g i v i n g the d e s i r e d octa-aza a n n u l e n e c o m p l e x . A s o l u t i o n of 200 m g [ C o ( C i H N ) ( C H C N ) ] ( C 1 0 ) , 0.5 m l of the a p p r o p r i a t e o r g a n o h y d r a z i n e , a n d 1 m l of the d e s i r e d a x i a l base w a s p r e p a r e d i n 15 m l C H C N . T o this s o l u t i o n , 482 m g p o t a s s i u m ferf-butoxide w a s a d d e d w i t h vigorous stirr i n g . T h e solutions b e c a m e a d e e p g r e e n - b l a c k color. T h e solutions w e r e filtered to r e m o v e the K C 1 0 a n d other i n s o l u b l e residues. A i r w a s t h e n b u b b l e d t h r o u g h the solution for several m i n u t e s . A n e x o t h e r m i c r e a c t i o n ensues d u r i n g w h i c h N is g i v e n off a n d the p r o d u c t crystallizes f r o m the solution. T h e p r o d u c t was filtered, w a s h e d w i t h C H C N , a n d t h e n d r i e d in vacuo. 0

: {

2

4

8

3

0

0

3

2

4

2 0

8

2

3

4

2

3

[ F e ( C i H i N ) ( C H N ) ] . A solution was prepared b y dissolving 200 m g [ F e ( C i o H N ) ( C H C N ) ] ( C 1 0 ) , 0.5 m l p y r i d i n e , a n d 160 m g ( 4 e q u i v a l e n t s ) p o t a s s i u m ter£-butoxide i n 20 m l a c e t o n i t r i l e u n d e r N atmosphere. T h e s o l u t i o n darkens c o n s i d e r a b l y to b r o w n i s h b l a c k o n m i x i n g . T h e s o l u t i o n was c e n t r i f u g e d to r e m o v e K C 1 0 a n d other i n s o l u b l e residues. A s o l u t i o n of 482 m g ( 4 e q u i v a l e n t s ) [Fe(acac) ], d i s s o l v e d i n a m i n i m u m of C H C N , was a d d e d to the s o l u t i o n c o n t a i n i n g the m a c r o c y c l i c c o m p l e x . T h e p r o d u c t begins c r y s t a l l i z i n g o n the sides of the r e a c t i o n vessel after several m i n u t e s ; h o w e v e r , m a x i m u m y i e l d s ( 1 5 % ) w e r e o b t a i n e d w h e n the s o l u t i o n w a s c h i l l e d i n a n ice b o x 12 h r . 0

4

8

5

2 0

8

5

2

3

2

4

2

2

4

3

3


382

INORGANIC

T h e product was then d r i e d in vacuo.

filtered

COMPOUNDS WITH

UNUSUAL PROPERTIES

under N , washed w i t h ethanol, and 2

Results and Discussion T h e r e a c t i o n of 2,3-butane d i h y d r a z o n e w i t h f o r m a l d e h y d e a n d cer t a i n d i v a l e n t t r a n s i t i o n m e t a l perchlorates leads to the f o r m a t i o n

of

b i s - a - d i i m i n e m a c r o c y c l i c complexes, II. U n d e r s u i t a b l e c o n d i t i o n s , these complexes u n d e r g o a f o u r - e l e c t r o n l i g a n d o x i d a t i o n , w i t h t w o a d d i t i o n a l d o u b l e b o n d s b e i n g i n t r o d u c e d i n t o the m a c r o c y c l i c l i g a n d s . D e p r o t o n a t i o n also occurs i n each of the s i x - m e m b e r e d chelate rings r e s u l t i n g i n the f o r m a t i o n of

completely

conjugated


complexes (see the S c h e m e ) .

16V-electron m a c r o c y c l i c

ligand

O x i d a t i o n of the s i m p l e m a c r o c y c l i c c o m

plexes II occurs u n d e r m i l d c o n d i t i o n s i f a s u i t a b l e base is present to remove

a p r o t o n f r o m the h y d r a z i n e l i n k a g e , thus f a c i l i t a t i n g l i g a n d

oxidation.

T h e s e h y d r a z i n e protons c a n sometimes b e r e m o v e d b y r e l a -

NH \2+

H

H

N

H

H

2

I

( 0 ) 2

2

+

N

^

N

H II

Ilia

t i v e l y w e a k bases s u c h as p y r i d i n e ; the ease of p r o t o n r e m o v a l d e p e n d s g r e a t l y on the c e n t r a l m e t a l . A t least one p r o t o n is r e m o v e d f r o m t h e n i c k e l ( I I ) i o n i z a t i o n i n the presence of p y r i d i n e . A m u c h stronger base, terf-butoxide

i o n , is n e e d e d to effect p r o t o n r e m o v a l a n d to f a c i l i t a t e

ligand oxidation. A f e w c o m m e n t s c o n c e r n i n g the p o s s i b i l i t y of i s o m e r i z a t i o n a m o n g these o c t a z a complexes is a p p r o p r i a t e . T h e n i t r o g e n atoms of the h y d r a z i n e l i n k a g e are a m b i d e n t a t e , a n d c o o r d i n a t i o n to e i t h e r n i t r o g e n m a y o c c u r , d e p e n d i n g o n w h e t h e r the 2 , 3 - b u t a n e d i h y d r a z o n e has the syn-anti or anti-anti c o n f i g u r a t i o n . T h r e e isomers a r e p o s s i b l e f o r e a c h f o r m u l a g i v e n : t w o 5-6-5-6 chelate systems ( o n e of D n s y m m e t r y , I l i a , a n d one of 2

Ch 2

s y m m e t r y , IHb a n d one 5-5-6-6 chelate system, IIIc). E a c h d e p i c t e d

d o u b l e b o n d a r r a n g e m e n t represents o n l y o n e of m a n y v a l e n c e tautomers. C o m p l e t e l y c o n j u g a t e d Ιβπ-electron l i g a n d complexes of C n 2

symmetry,

IHb, h a v e b e e n p r e p a r e d b y t w o m e t h o d s . I n t h e first, r e p o r t e d b y B a l d -


30.

GOEDKEN

AND

PENG

w i n a n d co-workers

Octa-aza

Annulene

383

Complexes

( 8 ) , t h e free l i g a n d ( w h i c h has C h

symmetry)

2

is

f o r m e d first a n d t h e n the m e t a l i o n is i n s e r t e d . A l t e r n a t i v e l y , i t is p o s s i b l e to o b t a i n some C h c o m p l e x e s i n s m a l l y i e l d s i m p l y b y m i x i n g the b i a c e t y l ,


2

CH

3

IIIc

IHb metal perchlorate, hydrazine, a n d aldehyde

together

i n a solution

a c e t o n i t r i l e (9, J O ) . T h e p r o p e r t i e s of c o m p l e x e s w i t h D q u i t e different f r o m those of c o m p l e x e s w i t h C

2h

symmetry.

T h e N M R s p e c t r u m of 2 , 3 - b u t a n e d i h y d r a z o n e l a t e d , i t has the anti-anti

of

s y m m e t r y are

21l

confirms that, as i s o

c o n f i g u r a t i o n as s h o w n i n S t r u c t u r e I .

Since

α - d i i m i n e l i g a n d s are g o o d c h e l a t i n g l i g a n d s b e c a u s e of e n h a n c e d

bond

i n g a t t r i b u t a b l e to the π-acceptor a b i l i t y of the α - d i i m i n e m o i e t y , i t is not surprising that the resultant complexes have the symmetrical

D

2h

s t r u c t u r e . I n g e n e r a l , this o v e r a l l d o n o r a t o m a r r a n g e m e n t is m a i n t a i n e d w h e n the b i s - a - d i i m i n e c o m p l e x e s are f u r t h e r o x i d i z e d . T h e c o p p e r c o m p l e x appears to be a n e x c e p t i o n . T h e i d e n t i t i e s of the o x i d i z e d p r o d u c t s w e r e e s t a b l i s h e d b y v a r i o u s spectroscopic a n d crystallographic techniques. plexes c o n t a i n i n g the C i o H i N 4

8

T h e I R s p e c t r a of

l i g a n d w e r e d e v o i d of a n y

com

absorptions

i n the r a n g e n o r m a l l y a s c r i b e d to N - H v i b r a t i o n s , a n d t h e y w e r e T a b l e I.

Properties of O x i d i z e d Complexes

[Ni (CioHi N )] 2 [Co ( C H N ) (C5H5N) ] I [Fe ( C i o H N ) (C5H5N) ] 1 0

4

8

1 4

8

1 4

8

2

2

3

diamagnetic diamagnetic diamagnetic

302

( Fe)


5 6

also

384

INORGANIC

COMPOUNDS WITH

UNUSUAL PROPERTIES

d e v o i d of a n y absorptions a t t r i b u t a b l e to p e r c h l o r a t e anions. M a s s spectra of the m o l e c u l a r species also e s t a b l i s h e d that the m a c r o c y c l i c l i g a n d h a d a w e i g h t of 246 w h i c h is consistent w i t h the state of o x i d a t i o n v i s u a l i z e d i n the Scheme.

Some properties of these o x i d i z e d complexes are g i v e n

i n T a b l e I. T h e I R spectra of these complexes

a n d of the

organo-cobalt(III)

complexes i n T a b l e I I w e r e of three types. T h o s e of the c o b a l t a n d i r o n complexes w e r e v e r y s i m i l a r w h i c h suggests that the m a c r o c y c l i c l i g a n d s w e r e of the same g e o m e t r i c a l isomer a n d c o n t a i n e d a s i m i l a r p a t t e r n of d e r e a l i z a t i o n . T h e spectra of the N i a n d C u complexes d i f f e r e d signific a n t l y f r o m e a c h other a n d also f r o m those of the F e a n d C o complexes.


F u r t h e r m o r e , the s p e c t r u m of the C u c o m p l e x w a s i d e n t i c a l to that of the [ N i ( C i o H

1 4

a c t e r i z e d (11),

N ) ] of C n s y m m e t r y , w h i c h has b e e n s t r u c t u r a l l y c h a r 2

8

w h i c h suggests that i s o m e r i z a t i o n f r o m a s t r u c t u r e w i t h Table II.

1 0

H

N ) (py)(CH )]°

1 4

T, °C

Solvent

Complex [Co(C

N M R D a t a f o r the N e w

8

CDC1

3

3

d -py 5

[Co(C

1 0

H

CDCI3

+50°C

CDCI3

-50°C

N )(py)(C H )]°

1 4

8

2

5

CDCI3

[Co(C [Co(C

1 0

H H

1 4

N ) (py) ( C H ) ] o N ) (4-picoline) ( C H ) ] °

CDC1 CDC1

[Co(C

1 0

H

1 4

N ) (3-picoline) ( C H ) ] °

CDC1

[Co ( C [Co(C

1 2

H N ) (NH2NHCH3) ( C H ) ] H N ) (py) ( C H ) ]

[Co(C

2 2

H

1 0

1 0

1 4

8

5

3

8

1 4

1 8

2 2

6

8

3

8

3

8

N ) (py) ( C H ) ] 8

3

1 0

1 6

1 4

8

3

8

3

CDC1 4

2

3

6

0 d

[Co(C H N ) ( C H C N ) ] (C10 ) [ C o ( C i o H N ) ( C N ) ( C H ) Y'

3

d -DMSO CDC1

0

0 d

3

3

3

CD N0 d -py & D 0

e

3

8

5

2

2

The numbers in parentheses refer to integrated intensity. * The phenyl and pyridine resonances overlap and cannot be distinguished. Broad peak, probably N H of C H N H N H . The ligand was modified by placing methyls on C ( l ) and C(4) (Figure 1).

a

0

3

2

d


30.

GOEDKEN

AND PENG

Octa-azd

s y m m e t r y to one w i t h C

D

2Jl

2h

Annulene

385

Complexes

s y m m e t r y h a d o c c u r r e d . T h i s w a s essen

t i a l l y c o n f i r m e d b y c o m p a r i n g the X - r a y p o w d e r p a t t e r n s of the C u a n d t h e N i c o m p l e x e s ; t h e p a t t e r n of t h e C u c o m p l e x w a s v i r t u a l l y i d e n t i c a l to that of t h e t r i c l i n i c f o r m of t h e N i o c t a - a z a a n n u l e n e c o m p l e x of symmetry.

(The C

2h

c o m p l e x of

triclinic and orthorhombic. )

C

2h

N i occurs i n two crystalline forms,

T h e C u c o m p l e x w a s t h e n o x i d i z e d to t h e

c o r r e s p o n d i n g C u ( I I I ) c o m p l e x w h i c h gave a species w i t h a l o w s p i n d

s

c o n f i g u r a t i o n t h a t w a s s u i t a b l e f o r N M R studies. T h e m e t h y l r e g i o n

of the Ή N M R c o n s i s t e d of t w o singlets at 2.43 a n d 2.75 p p m ( δ ) , w h i c h f u r t h e r s u b s t a n t i a t e d o u r c o n t e n t i o n that i s o m e r i z a t i o n h a d o c c u r r e d . T h e n i c k e l c o m p l e x e s of s t o i c h i o m e t r y N i C i H i N 0

or C


2h

symmetry (Structures Ilia and H l b ) .

4

have either D h

8

2

The C

2h

s t r u c t u r e is a

m o n o m e r ; i t has a w e l l d e f i n e d N M R s p e c t r u m a n d p r o p e r t i e s t h a t are g e n e r a l l y consistent w i t h other f o u r - c o o r d i n a t e s q u a r e p l a n a r n i c k e l ( I I )

Organo-Cobalt(III) Complexes" Assignments—Chemical

CÏT, (ligand)

C^R (C-R)

Shifts

(B) "

Co-R

0.62 ( 1 2 , 8 ) , 4.32 (2,s)

8.04(3,8)

0.49 (12,s) , 4 . 2 2 (2,8) 0.57 (12,s), 4.23 (2,s)

9.00 (3,s) 8.16(3,8)

Axial

Ligand

8.54-8.81 (3,m) ; 13.77-14.07 (2,m)

8.56-8.85 (3,m) ; 13.84-14.10 (2,m) 8.49-7.74 ( 3 , m ) ; 0.74(12,s), 4.57(2,8) 7.59(3,8) 13.62-13.87 (2,m) 8.30-8.67 ( 3 , m ) ; 8.98 0.59(12,s), 4.33(2,8) 13.47-13.97 (2,m) ( 2 , q / =•• 4 cps) 4.10 ( 3 , t , J = 7 cps) 8.16-8.83 (6,m) 12.75-13.08 ( 4 , m ) ' 0.53(12,s), 4.42(2,8) 3.06 ( 3 , 8 ) , 8.33-8.55 (2,m) ; 0.61 (12,s), 4.34 (2,s) 8.01(2,8) 13.63-13.86 (2,m) 0.60 (12,s), 4.34 (2,s) 3.15 (3,s), 8.35-8.60 (2,m) ; 8.03 (3,s) 13.56-13.90 (2,m) 2.63 (3,e), 4.33 ( ? ) ' 0.60(12,s), 4.40(2,8) 7.82(3,8) 8.21-8.37 ( 3 , m ) ; 6.56 (3,s) 0.91 (12,s), 0.78 (6,8) 12.52-12.77 (2,m) 8.30-8.70 ( 3 , m ) ; 0.83 (12,s), 6.83-7.50 (10,m) 7.07 (3,s) 12.80-13.30 (2,m) 2.37 (3,s) 3.73 (3,s) 2 . 1 5 ( 1 2 , 8 ) , 6.62(2,8) 0.95 (12,s), 4.95 (2,s) 6.94 (3,8) The ligand was protonated on nitrogen. [ C o ( C i o H i 4 N ) ( p y ) ( C H 3 ) ] ° was dissolved i n d5-py, then saturated N a C N i n H2O was added. e

1

8


386

INORGANIC

complexes.

COMPOUNDS WITH

O n t h e other h a n d , the D

2 7 l

UNUSUAL PROPERTIES

isomer is a c t u a l l y a d i m e r t h a t

contains a N i - N i b o n d a n d gives a w e a k p a r e n t p e a k i n the mass spec t r u m at 608. T h e c o m p o u n d is v i r t u a l l y i n s o l u b l e i n a l l solvents, g i v i n g only a faint color i n C H C 1

3

or C H C 1 . F u r t h e r m o r e , the s o l u t i o n spectra 2

2

are different f r o m those o b t a i n e d i n the s o l i d state; this suggests some p o s s i b l e d i m e r - d i m e r i n t e r a c t i o n i n the s o l i d state.

T h e solutions are

u n s t a b l e ; t h e y react m o d e r a t e l y r a p i d l y w i t h m o l e c u l a r o x y g e n a n d d e c o m p o s e s l o w l y e v e n i n r i g o r o u s l y degassed c h l o r o c a r b o n solvents.

The

u n u s u a l i m p l i c a t i o n s of these observations p r o m p t e d us to d e t e r m i n e the c r y s t a l structure of the c o m p l e x . E x h a u s t i v e efforts to g r o w

s u i t a b l e crystals afforded

only a tiny


s p e c i m e n , 0.024 X 0.054 X 0.23 m m , w h i c h w a s o b t a i n e d b y the s l o w d i f fusion (CioH

of

oxygen

into a

10:1

a c e t o n i t r i l e - p y r i d i n e s o l u t i o n of

N )] (C10 ) .

C r y s t a l d a t a : space g r o u p C 2 / c , a =

h — 18.534(9) A , c =

13.123(7) A , cos β — - 0 . 8 1 2 1 ( 2 ) ,

Pexp

=

2 0

8

4

1.70 g / c m

3

2

for w h i c h Ζ =

[Ni-

15.497(9) A , P c e l c d

=

1.718,

8. T h e t i n y c r y s t a l size a n d c o n s e q u e n t

w e a k i n t e n s i t y of the diffractions necessitated the c o l l e c t i o n of q u a d r a n t s of d a t a . D a t a w e r e c o l l e c t e d w i t h M o =

0.5946.

three

Κα r a d i a t i o n to s i n θ/λ

T h e e q u i v a l e n t d a t a w e r e m e r g e d , a n d the processed

data

f r o m a l l 2077 i n d e p e n d e n t reflections m e a s u r e d w e r e used i n the s o l u t i o n a n d refinement of the s t r u c t u r e . T h e s t r u c t u r e w a s s o l v e d b y the h e a v y

Figure 1. Molecular structure and interatomic distances of the [Ni(C dimer. The estimated standard deviations are as follows: Ni-N 0.005 A; N-N, C-N, and C-C distances, 0.006-0.008 A.


H N )] distances, 10

U

8


30.

GOEDKEN

AND PENG

Octd-azd Annulene

Complexes

387

Figure 2. Pdcking diagmm of the dimers indicdting the stdcking of the molecules in the unit cell a t o m m e t h o d a n d r e f i n e d w i t h a n i s o t r o p i c t h e r m a l p a r a m e t e r s for a l l n o n h y d r o g e n atoms.

A l l h y d r o g e n atoms w e r e l o c a t e d o n a

difference

F o u r i e r , a n d i d e a l i z e d coordinates w e r e r e d e t e r m i n e d a s s u m i n g s t a n d a r d g e o m e t r y a n d C - H distances of 0.95 A .

T h e s e w e r e i n c l u d e d at

positions i n the final refinement. A t c o n v e r g e n c e , R i = 6 . 1 % w h e r e Κχ — 2|Fo -

Fc|/2|Fo| and R

2

=

10.4 a n d R

[Sw(|Fo| -

fixed 2

—

|Fc|)7

2w|Fo| ] - . 2

0

5

T h e structure consists of a d i m e r i c m a c r o c y c l i c c o m p l e x c o n t a i n i n g a N i - N i b o n d w i t h the d i m e r i c u n i t s s t a c k e d a l o n g the c c r y s t a l axis ( F i g ures 1 a n d 2 ) .

T h e r e are a n u m b e r of u n u s u a l features associated w i t h

this structure. F i r s t , the d i m e r s c o n t a i n a N i - N i b o n d of l e n g t h 2.784(2) A . A l t h o u g h N i - N i b o n d s are n o t c o m m o n , a n i n c r e a s i n g n u m b e r h a v e b e e n f o u n d w i t h b r i d g i n g N - d o n o r or S-donor l i g a n d s i n recent years w i t h N i - N i b o n d s r a n g i n g i n l e n g t h f r o m 2.38 to 2.81 A

(12,13,14,15,16,17).

T h a t m o s t c l o s e l y r e l a t e d to ours contains a d i a n i o n i c q u a d r i d e n t a t e N - d o n o r l i g a n d a n d has a m e t a l - m e t a l distance of 2.81 A . T h e distances i n the latter s t r u c t u r e a n d i n the N i d i m e r are c o m p a r a b l e to the C o - C o d i s t a n c e , 2.794 A , i n the [ C o ( C N ) ] " d i m e r w h i c h contains a single 5

abond

3

(18,19).

H o w e v e r , attractive i n t e r a c t i o n b e t w e e n the t w o m a c r o c y c l i c m o i e ties i n a d d i t i o n to a N i - N i σ b o n d m u s t b e present to a c c o u n t f o r the e c l i p s e d c o n f o r m a t i o n of the t w o units f o r m i n g the d i m e r .

Although

h i g h l y d e l o c a l i z e d systems s u c h as p o r p h y r i n a n d c h l o r o p h y l - t y p e m o l e cules h a v e attractive τ τ - π i n t e r a c t i o n s l e a d i n g to a g g r e g a t i o n i n s o l u t i o n , a staggered a r r a n g e m e n t of t h e atoms t h a t m i n i m i z e s n o n b o n d i n g r e p u l -


388

INORGANIC

COMPOUNDS WITH

UNUSUAL

PROPERTIES

sions is p r e f e r r e d . T h e m o s t l i k e l y e x p l a n a t i o n for the e c l i p s e d a r r a n g e m e n t of o u r d i m e r is that, e v e n at the r e l a t i v e l y l a r g e N i - N i s e p a r a t i o n , some δ b o n d i n g is present b e t w e e n the t w o m e t a l ions. T h e fact t h a t t h e N i atoms are d i s p l a c e d 0.104 A f r o m t h e p l a n e of f o u r n i t r o g e n t o w a r d s one a n o t h e r lends some c r e d e n c e to this v i e w p o i n t .

p l a n a r s e p a r a t i o n of the least squares p l a n e defined b y the t w o c y c l i c r i n g s is 3.00 A a n d n o n b o n d i n g

atoms

The intermacro-

repulsions m a y prevent

closer

a p p r o a c h of the t w o m e t a l atoms. T h e d o u b l e b o n d s of the m a c r o c y c l i c pletely delocalized;

the average

l i g a n d are essentially

com

C - C a n d C - N distances i n the

five-

m e m b e r e d r i n g s , 1,396 a n d 1.357 A , are v e r y close to the a c c e p t e d

C-C


distances of b e n z e n e a n d the a r o m a t i c C - N d i s t a n c e of p y r i d i n e , 1.35 A . T h e N - N a n d C - N distances of the s i x - m e m b e r e d chelate r i n g s are also i n t e r m e d i a t e b e t w e e n those e x p e c t e d for single a n d d o u b l e b o n d s .

This

degree of d e r e a l i z a t i o n is m u c h m o r e extensive t h a n that o b s e r v e d the C h

s t r u c t u r e ( w h i c h has a n a l t e r n a t i n g d o u b l e b o n d

2

or i n the C o ( I I I )

c o m p l e x e s of D

s y m m e t r y (see

2h

in

arrangement)

below).

T h i s differ

ence i n d e r e a l i z a t i o n accounts for the differences i n the I R spectra of the v a r i o u s octa-aza a n n u l e n e c o m p l e x e s w h i c h w a s c o m m e n t e d u p o n e a r l i e r . T h e p a c k i n g a r r a n g e m e n t of the d i m e r molecules is significant.

The

adjacent d i m e r s are r e l a t e d b y a c r y s t a l l o g r a p h i c t w o - f o l d axis a n d are s t a c k e d a l o n g the c c r y s t a l axis w i t h a N i - N i s e p a r a t i o n of 3.800 A . T h i s s t a c k i n g , a n d possible m e t a l - m e t a l i n t e r a c t i o n of adjacent d i m e r s , m a y a c c o u n t for the l i m i t e d s o l u b i l i t y of the c o m p l e x .

O n e other i n t e r e s t i n g

p o i n t is that a 0.50-A m o v e m e n t of the N i atoms f r o m one another i n t h e d i m e r w o u l d l e a d to a n e w d i m e r w i t h e q u i v a l e n t N i - N i s e p a r a t i o n b u t w i t h the m a c r o c y c l i c l i g a n d r o t a t e d 90° r e l a t i v e to one another. w o u l d a p p e a r to be a m o r e f a v o r a b l e a r r a n g e m e n t t h a n the one

This found

b e c a u s e i t w o u l d m i n i m i z e most of the r e p u l s i v e i n t e r a c t i o n s . T r u e x a n d H o l m ( 20 ) o b s e r v e d m o n o m e r - d i m e r e q u i l i b r i u m i n s o l u t i o n for t h e i r c a t i o n i c species,

[ N i ( M e H M e - 2 , 9 - d i e n e ) ] ; i n v i e w of o u r +

results, t h e i r d i m e r i c species m a y also c o n t a i n a N i - N i b o n d .

Although

o u r d i m e r c o m p l e x is d i a m a g n e t i c ( i.e., r e p e l l e d b y a m a g n e t i c field ) i n t h e s o l i d state, a l l samples i n v e s t i g a t e d gave a m o d e r a t e l y strong i s o t r o p i c ESR

s i g n a l , g = 2.001, i n d i c a t i n g some u n p a i r e d s p i n d e n s i t y i n t h e

7r-ligand system.

Since this s i g n a l is v e r y s i m i l a r to t h a t d e s c r i b e d

by

T r u e x a n d H o l m for t h e i r c a t i o n i c 15?r system, the s i g n a l w e observe m a y be c a u s e d b y a s m a l l i m p u r i t y of a n analogous c a t i o n i c species i n o u r samples. I n the c o b a l t c o m p l e x e s there are a g a i n r e m a r k a b l e differences the

properties

of

the

C

2h

and

D

2h

isomers.

The

C o (III)

in

complex,

[ C o ( C i H i N ) ( 0 Η Ν ) ] ΐ 3 ( t r i - i o d i d e a n i o n ) , is d i a m a g n e t i c , b u t a l l 0

4

8

5

δ

2


30.

GOEDKEN

Octa-aza

AND PENG

attempts to observe

its Ή

Annulene

389

Complexes

N M R spectrum failed, even w h e n it was

s c a n n e d o v e r the range of 100 to —100 p p m o n a B r u k e r 270 spectrometer. H o w e v e r , the o r g a n o - C o ( I I I )

complexes g a v e w e l l r e s o l v e d N M R spec

t r a , b u t the resonances w e r e s i g n i f i c a n t l y s h i f t e d f r o m t h e i r e x p e c t e d positions. I n g e n e r a l , the spectra w e r e c h a r a c t e r i z e d b y large d o w n f i e l d shifts for the l i g a n d s o c c u p y i n g a x i a l sites a n d h i g h field shifts f o r those protons l o c a t e d i n the e q u a t o r i a l p l a n e of t h e m a c r o c y c l i c l i g a n d ( T a b l e II).

F o r the

[Co(C

1 0

H

1 4

N ) (C H N)(CH )] 8

5

5

complex,

3

the

Co-CH

3

resonance is o b s e r v e d at 8.04 p p m ( δ ) , the p y r i d i n e resonances at 8.7 a n d 13.9 p p m , a n d the l i g a n d m e t h y l groups at 0.62 p p m . the C o ( I I I ) - a l k y l complexes w i t h the C

f o r m of the l i g a n d are

2h


c o o r d i n a t e , w i t h t y p i c a l N M R spectra C o - C H l i g a n d - C H ' s at 2.69 a n d 2.42 p p m (21). 3

complexes of the C h 2

I n contrast,

W h e r e a s the

f o r m of t h e l i g a n d are

five-

at 0.04 p p m a n d t h e

3

organo-Co(III)

five-coordinate

b e h a v e d " m a g n e t i c p r o p e r t i e s , the o r g a n o - C o ( I I I )

with "well

complexes of the

D

2h

f o r m of the l i g a n d are s i x - c o o r d i n a t e w i t h u n u s u a l m a g n e t i c p r o p e r t i e s . The Ή

N M R spectra d e p e n d m a r k e d l y o n ( a )

ligand, (b) (d)

changes

m i n o r changes i n the m a c r o c y c l i c l i g a n d , ( c )

temperature.

of the

axial

solvent, a n d

T h e s e observations h a v e l e d us to b e l i e v e t h a t the

a n o m a l o u s shifts are the r e s u l t of p a r a m a g n e t i c contact shifts a r i s i n g f r o m the t h e r m a l p o p u l a t i o n of a l o w - l y i n g t r i p l e t state. T h e spectra d e p e n d o n the n a t u r e of the a x i a l base, b u t not to the extent t h a t w e h a d h o p e d .

C h a n g i n g one n i t r o g e n d o n o r f o r another l e d

o n l y to m i n o r changes i n the spectra. H o w e v e r , e x c h a n g i n g p y r i d i n e f o r

Figure 3. interatomic

Two views of [Co(C H NsXCH )(NH NHCH )] with selected distances and angles. Left: view perpendicular to the plane of the molecule, and right: a simplified side view 10

u

s

2

s


390

INORGANIC

COMPOUNDS WITH

a 7r-acceptor s u c h as c y a n i d e l o w e r s t h e C o - C H 6.93 p p m . T h e a l k y l groups

produce

3

UNUSUAL

PROPERTIES

a b s o r p t i o n f r o m 8.04 to

a strong σ-trans effect; t h u s t h e

effect o f t h e a x i a l l i g a n d s ( t r a n s to t h e a l k y l g r o u p ) o n t h e e l e c t r o n i c s t r u c t u r e of t h e c o m p l e x is less t h a n m i g h t b e expected. T h e N M R spectra are also sensitive to m i n o r changes i n t h e m a c r o c y c l i c l i g a n d . S u b s t i t u t i n g m e t h y l groups f o r t h e h y d r o g e n atoms of C ( 1) and C(4)

(see F i g u r e 3), a p o s i t i o n r e l a t i v e l y i s o l a t e d f r o m t h e c o o r d i

n a t i o n sphere, shifts t h e a b s o r p t i o n of t h e C o ( I I I ) - C H to 6.56 p p m .

3

g r o u p f r o m 8.04

P r o t o n a t i o n of t h e l i g a n d b y a d d i n g p e r c h l o r i c a c i d to t h e

m o l e c u l a r c o m p l e x p r o d u c e s [ C o ( C i H i N ) ( C H C N ) ( C H ) ] ( C 1 0 ) 2, 6

0

8

3

3

4

a species w i t h a m o r e n o r m a l N M R s p e c t r u m — t h e C o ( I I I ) - C H


n a n c e appears a t 3.78 p p m .

reso

3

S u b s t i t u t i n g a p o l a r solvent, d - p y r i d i n e , f o r

C D C 1 results i n a d o w n f i e l d shift f o r C o ( I I I ) - C H 3

v a l u e of 9.0 p p m f o r t h e [ C o ( C

1 0

H

1 4

3

of a l m o s t 1 p p m to a

N ) (C H N) (CH )] 8

5

5

complex.

3

T h e strongest e v i d e n c e s u p p o r t i n g o u r c o n t e n t i o n t h a t t h e a n o m a l o u s NMR

spectra

are d u e to p a r a m a g n e t i c

contact

shifts a r i s i n g f r o m

a

t h e r m a l l y p o p u l a t e d t r i p l e t state is d e r i v e d f r o m t h e t e m p e r a t u r e d e p e n d e n c e of t h e N M R spectra

(Table

II).

C o o l i n g the sample

from

+ 5 0 ° to —50°C decreases t h e p o p u l a t i o n of t h e t r i p l e t state a n d shifts the a b s o r p t i o n m a x i m a of C o ( I I I ) - C H the direction expected

3

f r o m 8.16 p p m to 7.59 p p m i n

for a n increase i n t h e p o p u l a t i o n of t h e s i n g l e t

g r o u n d state.

T h e N M R spectra of t h e c o m p l e x e s are i n d e p e n d e n t

concentration

a n d reproducible

from

of

p r e p a r a t i o n to p r e p a r a t i o n , thus

e l i m i n a t i n g t h e p o s s i b i l i t y that contact shifts r e s u l t f r o m r a p i d e l e c t r o n e x c h a n g e b e t w e e n t h e c o b a l t ( I I I ) - a l k y l c o m p l e x e s a n d some p a r a m a g netic impurity. The [ C o ( C

1 0

H

1 4

N )(CnHnN) ]I 8

2

3

complex a n d the organo-Co(III)

complexes a l l give an isotropic E S R signal at room temperature, g 2.001 ( h a l f - w i d t h ^

=

40-80 g a u s s ) , w h i c h is i n d i c a t i v e of u n p a i r e d s p i n

d e n s i t y i n t h e ττ-ligand system.

T h e i n t e n s i t y of t h e s i g n a l f r o m t h e

o r g a n o - C o ( III ) c o m p l e x e s appears to b e w e a k e r b y a factor o f t e n t h a n the signal from the bispyridine complex. T h e c r y s t a l s t r u c t u r e of o n e of t h e o r g a n o - C o (III)

complexes was

d e t e r m i n e d i n o r d e r to define u n a m b i g u o u s l y t h e d o u b l e b o n d

arrange

m e n t a n d t h e extent of d e r e a l i z a t i o n i n t h e m a c r o c y c l i c l i g a n d , a n d t o s h e d s o m e l i g h t o n the m a g n e t i c p e c u l i a r i t i e s of these o r g a n o - c o b a l t ( I I I ) complexes. NHCH

3

C r y s t a l s of t h e h y d r a z i n e c o m p l e x ,

[Co(Ci H 0

23.377(3) A , c =

Pexp =

N ),NH -

3

tals of t h e c o m p o u n d b e l o n g to space g r o u p P 2 i / c , w i t h a = b =

1 4

8

) ( C H ) ] , w e r e s u i t a b l e for X - r a y s t r u c t u r a l d e t e r m i n a t i o n . 10.061(2) Α, β =

1.51(2) f o r w h i c h Ζ =

103.44(1)°,

P c & l c ( 1

2

Crys

6.961(1) A , — 1.526, a n d

4. A t o t a l of 5294 d a t a w e r e m e a s u r e d o n

a P i c k e r F A C S - 1 diffractometer w i t h M o Κα r a d i a t i o n ; 4106 i n d e p e n d e n t


30.

GOEDKEN

Octa-aza

A N D PENG

d a t a w i t h F values >

Annulene

Complexes

391

2 w e r e u s e d i n t h e s t r u c t u r a l refinement. T h e

structure was solved using the heavy atom method, a n d i t was refined b y f u l l m a t r i x least squares t e c h n i q u e s .

Refinement using anisotropic

t h e r m a l parameters f o r a l l n o n h y d r o g e n atoms ( w i t h c o n t r i b u t i o n s f o r a l l t h e h y d r o g e n atoms l o c a t e d f r o m a difference F o u r i e r a n d p l a c e d i n a s s u m i n g s t a n d a r d distances a n d g e o m e t r y ) c o n v e r g e d to R i = 4.2% a n d R

2

=

4.2%.

T h e m a c r o c y c l i c l i g a n d is flat a n d contains a n a - d i i m i n e

f u n c t i o n i n each

of the

five-membered

chelate r i n g s , a n d a t h r e e - a t o m ,

N - C - N , d e l o c a l i z e d system i n e a c h o f t h e s i x - m e m b e r e d chelate r i n g s ( F i g u r e 3). T h e angles defined b y N ( 2 ) - C ( l ) - N ( 3 ) a n d N ( 6 ) - C ( 4 ) N(7),

1 4 0 . 2 ( 2 ) ° a n d 1 3 9 . 4 ( 2 ) ° r e s p e c t i v e l y , a r e u n u s u a l l y w i d e . T h i s is


a p p a r e n t l y a t t r i b u t a b l e to t h e preference of t h e N - N - C l i n k a g e f o r a n a n g l e less t h a n 1 2 0 ° . T h e parameters of the i n n e r c o o r d i n a t i o n p o l y h e d r o n a r e t o t a l l y c o n sistent w i t h those r e p o r t e d f o r a n u m b e r of o r g a n o - c o b a l t ( I I I ) plexes (21) w i t h one e x c e p t i o n .

T h e average c o b a l t - n i t r o g e n

com

(planar)

d i s t a n c e , 1.866 A , is shorter, a l t h o u g h o n l y s l i g h t l y , t h a n i n other o r g a n o cobalt(III)

complexes.

T h e c r y s t a l structures of three c o b a l o x i m e

plexes, w h i c h are the most closely r e l a t e d to o u r o r g a n o - c o b a l t

com

complexes,

h a v e m e a n C o - N ( p l a n a r ) distances w h i c h v a r y b e t w e e n 1.88 a n d 1.90 A (22,23, 24). A n a l t e r n a t i v e e x p l a n a t i o n f o r t h e a b n o r m a l N M R shifts is t h a t t h e 16ττ d i a n i o n i c l i g a n d is b e h a v i n g as a n a n t i a r o m a t i c r i n g system. T h e o b s e r v e d shifts are close i n m a g n i t u d e to those o b s e r v e d f o r t h e d i a n i o n of 15,16-dimethyldihydropyrene;

this demonstrates a n t i a r o m a t i c c h a r a c

ter (25); viz., the m e t h y l protons o n the i n s i d e of t h e d i h y d r o p y r e n e r i n g a p p e a r at v e r y l o w field, δ =

21.0 p p m , c o m p a r e d w i t h t h e h i g h

p o s i t i o n , —4.25 p p m , f o r t h e p a r e n t , u n c h a r g e d a r o m a t i c r i n g .

field

However,

it is difficult to see h o w this i n t e r p r e t a t i o n c o u l d a c c o u n t f o r t h e t e m p e r a ture v a r i a t i o n , solvent d e p e n d e n c e , a n d E S R signals t h a t are o b s e r v e d f o r t h e m a c r o c y c l i c C o ( I I I ) complexes discussed. F u r t h e r m o r e , t h e results of t h e c r y s t a l l o g r a p h i c analysis a r e n o t c o m p a t i b l e w i t h those n e e d e d to f u l f i l l t h e a n t i a r o m a t i c r e q u i r e m e n t , f o r example, a n d the alternating double b o n d arrangement.

A l t h o u g h the

d o u b l e b o n d s are l o c a l i z e d , t h e y are l o c a l i z e d i n t h e f o r m of t w o bis-ad i i m i n e chelate l i n k a g e s a n d t w o 3-atom d e l o c a l i z e d systems, e a c h c o n t a i n i n g a n e g a t i v e charge. Conclusions A n u m b e r of g e o m e t r i c a l a n d v a l a n c e isomers o f t h e d i h y d r o - o c t a z a a n n u l e n e m e t a l complexes findings

have been isolated a n d characterized. T h e

are s u m m a r i z e d i n T a b l e I I I . I t is n o t e w o r t h y t h a t different


392

INORGANIC

Table III. 0

[NiL] [Ni L ]

Co„ ; I H b £> ;,;iiia

2

2

[CuL] [Cu L] [CoL(NH NHCH )CH ]

D;

[CoL(CH )]

C „;IIIb

i n

+ 1

2

3

3

3


•L =

Ci H 0

Ch ) IHb C J, ') I H b 2

2

2h

2

1 4

WITH

UNUSUAL

PROPERTIES

S u m m a r y of L i g a n d Structures Ligand Structure

Complex

2

COMPOUNDS

Ilia

Comments l o c a l i z e d double bonds delocalized double bonds ; N i - N i bond l o c a l i z e d double bonds l o c a l i z e d double bonds α-diimine chelate r i n g s ; a l l y l i c t y p e of d e r e a l i z a t i o n i n s i x m e m b e r e d chelate rings l o c a l i z e d double bonds

N . 8

m e t a l ions t e n d to s t a b i l i z e different g e o m e t r i c a l structures, a n d f u r t h e r m o r e that, for a g i v e n g e o m e t r i c a l isomer, different m e t a l ions result i n d i f f e r i n g extent of d o u b l e b o n d d e r e a l i z a t i o n t h r o u g h o u t

the l i g a n d .

T h e v a r i a t i o n i n d o u b l e b o n d d e r e a l i z a t i o n for these systems is f a r greater t h a n f o u n d w i t h aromatic n i t r o g e n d o n o r ligands.

T h e crystal

structures of a large n u m b e r of p h e n a n t h r o l i n e complexes h a v e b e e n d e t e r m i n e d ; there is v e r y little c h a n g e i n the C - N b o n d lengths w i t h i n the

five-membered

chelate rings o n g o i n g f r o m metals w i t h strong π-

b a c k b o n d i n g tendencies ( w h i c h m i g h t b e e x p e c t e d to s t a b i l i z e t h e a - d i i m i n e f o r m of p h e n a n t h r o l i n e ) to m e t a l ions w i t h n e g l i g i b l e b a c k b o n d i n g tendencies ( 2 6 ) .

Literature Cited 1. Busch, D. H., "Alfred Werner Commemoration Volume," p. 174, Verlag Helv. Chimica Acta, Basel, 1967. 2. Busch, D. H., Farmery, K., Goedken, V., Katovic, V., Melnyk, Α., Sperati, C, Tokel, N., ADV. CHEM. SER. (1971) 100, 44. 3. Schrauzer, G. N., Acc. Chem. Res. (1969) 2, 72. 4. Lovecchio, F., Gore, E., Busch, D., J. Am. Chem. Soc. (1972) 94, 4529. 5. Takvoryan, N., Farmery, K., Katovic, V., Lovecchio, F., Gore, E., Anderson, L., Busch, D., J. Am. Chem. Soc. (1974) 96, 731. 6. Busch, D. H., Bailar, J., J. Am. Chem. Soc. (1956) 78, 1137. 7. Goedken, V., Peng, S.-M., Park, Y.-A., J. Am. Chem. Soc. (1974) 96, 284. 8. Baldwin, J., Holm, R., Harper, R., Huff, J., Koch, S., Truex, T., Inorg. Nucl. Chem. Lett. (1972) 8, 393. 9. Goedken, V., Peng, S.-M., unpublished data. 10. Goedken, V., Peng, S.-M., Chem. Commun. (1973) 62. 11. Goedken, V., Peng, S.-M., J. Am. Chem. Soc. (1973) 95,5773. 12. Bonamico, M., Dessy, G., Fares, V., Chem. Commun. (1969) 697. 13. larcow, O., Schulz, H., Nast, R., Angew. Chem. (1970) 82, 43. 14. Corbett, M., Hoskins, B., Chem. Commun. (1969) 1602. 15. Bonamico, M., Dessy, G., Fares, V., Chem. Commun. (1969) 1106. 16. Bailey, N., James, T., McCleverty, J., McKenzie, E., Moore, R., Worthington, J., Chem. Commun. (1972) 681.


30. GOEDKEN AND PENG Octd-dzd Annulene Complexes

Sacconi, L., Mealli,C.,Gatteschi, D., Inorg. Chem. (1974) 13, 1985. Brown, L., Raymond, K., Goldbert, S.,J.Am. Chem. Soc. (1972 ) 94, 7664. Simon, G., Adamson, Α., Dahl, L., J. Am. Chem. Soc. (1972) 94, 7654. Truex, T., Holm R., J. Am. Chem. Soc. (1972) 94, 4529. Dodd, D., Johnson, M., J. Orgdnomet. Chem. (1973) 52, 34. Crumbliss, Α., Bowman, J., Gaus, P., McPhail, Α., Chem. Commun. (1973) 415. 23. McFadden, D., McPhail, Α., J. Chem. Soc. Dalton Tmns. (1974) 363. 24. Lenhert, P., Chem. Commun. (1967) 980. 25. Mitchell, R., Klopfenstein, C., Boekelheide, V., J. Am. Chem. Soc. (1969) 91, 4931. 26. Frenz, B., Ibers, J., Inorg. Chem. (1972) 11, 1109. RECEIVED January 24, 1975. Work supported by the National Institutes of Health grant HL14827 and the Materials Research Laboratory sponsored by the National Science Foundation. Downloaded by UNIV OF BATH on July 3, 2016 | http://pubs.acs.org Publication Date: June 1, 1976 | doi: 10.1021/ba-1976-0150.ch030

17. 18. 19. 20. 21. 22.

393


Synthesis and Study of Octa-aza Annulene Complexes With Unusual

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