Inorganic Compounds with Unusual Properties - ACS Publications

29 Rhodium(I) Complexes of Macrocyclic

Downloaded by NORTH CAROLINA STATE UNIV on May 6, 2015 | http://pubs.acs.org Publication Date: June 1, 1976 | doi: 10.1021/ba-1976-0150.ch029

Tetradentate Thioethers WILLIAM D. LEMKE, and DARYLE H. BUSCH

KENTON

E.

TRAVIS,

NURHAN

E.

TAKVORYAN,

The Ohio State University, Columbus, Ohio 43210

Reduction

of the rhodium(III)

macrocyclic (TTP)

thioethers

complexes

1,4,8,11

four-coordinate,

cationic

The anions are not coordinated PF -,

BF -,

6

4

NCS , -

not react with ligands combine 2

tetradentate

and 13,14-benzo-1,4,8,11-tetrathiapentadecane

produces

Ο,

of the

-tetrathiacyclotetradecane

like

CH, 2

with

TCNE,

I,

or

-

4

-

Furthermore,

CO, and PPh . 3

and

H.

Thus,

R h ( T T P ) + undergoes

Rh(TTP) including

Rh(TTX) . +

X =

addition

does

+

back-bonding does,

+

BF , 3

however, SO ,

with

NO , +

2

it is a substantial

oxidative

ClO4-,

Rh(TTP)

donors including

many eltctrophiles +

(TTX) and

+

in [Rh(TTP)]X,

Br .

electron-pair

Rh(TTP)

nucleophile. CH I, 3

CH6

5

thereby increasing both the coordination

number

and the oxidation

ever, it fails to react with

*T*he A

expectation

that, b y

state of Rh by two;

how

H. 2

analogy

to p h o s p h i n e s , thioethers s h o u l d

f u n c t i o n as π a c c e p t o r l i g a n d s a n d t h e r e b y s t a b i l i z e l o w o x i d a t i o n

state c o m p o u n d s , l e d s e v e r a l investigators to t r y to s y n t h e s i z e t h i o e t h e r c o m p l e x e s of r h o d i u m ( I ) . W a l t o n ( I ) t r e a t e d [ R h ( D T H ) C l ] C l ( D T H 2

=

CH SCH CH2SCH 3

2

3

) w i t h ethanolic potassium hydroxide, a reducing

system d e v e l o p e d b y C h a t t a n d S h a w ( 2 ) , b u t he f a i l e d to o b t a i n a c o m p l e x of the e x p e c t e d t y p e . A t t e m p t s to o b t a i n r h o d i u m ( I ) d e r i v a t i v e s b y reducing

[ R h ( D T H ) C l > ] C l w i t h s o d i u m b o r o h y d r i d e or b y 2

electro

c h e m i c a l methods were equally unsuccessful. Chatt and co-workers

(3)

a t t e m p t e d to p r o d u c e r h o d i u m ( I ^ t h i o

e t h e r c o m p l e x e s b y s u b s t i t u t i o n reactions. N o s u c h p r o d u c t w a s o b t a i n e d 358

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

29.

L E M K E

E T

Macrocyclic

AL.

Tetradentate

359

Thioethers

b y t h e r e a c t i o n of [ R h ( C O ) C l ] w i t h C H S R ( R = M e , i - P r , or C H ) , 2

2

6

5

6

5

a n d r e a c t i o n of the same r h o d i u m ( I ) c o m p l e x w i t h t r i d e n t a t e thioethers ( R S C H C H ) S ( R = n - P r or C H ) a n d w i t h C H C ( C H S E t ) 2

2

2

6

5

3

2

yielded

2

oils. A p o l y m e r i c m a t e r i a l of the f o r m u l a t i o n [ R h C l ( C O ) ( D T H ) ] o b t a i n e d f r o m the r e a c t i o n of [ R h ( C O ) C l ] 2

2

n

a n d D T H i n acetone.

was The

c o m p o u n d e x h i b i t e d v e r y l o w c a r b o n y l frequencies ( 1830 a n d 1800 c m " ) 1


w h i c h w e r e a t t r i b u t e d to b r i d g i n g c a r b o n y l s , a n d t h e c o m p o u n d

was

t h o u g h t to b e a t r i m e r or a h i g h e r o l i g o m e r .

T h e corresponding product

obtained

was

formulated

similarly;

h o w e v e r , its I R s p e c t r u m h a d five c a r b o n y l b a n d s , a n d i t w a s

with

CH CH SCH CH SCH CH

suggested

that the t r i m e r i c or t e t r a m e r i c s t r u c t u r e i n v o l v e d h a l o g e n

or

3

2

2

2

2

3

sulfur

b r i d g e s . W e r e p o r t here the first, w e l l c h a r a c t e r i z e d m o n o m e r i c r h o d i u m ( I ) - t h i o e t h e r complexes.

T h e y w e r e p r e p a r e d b y the r e d u c t i o n of r h o

d i u m ( I I I ) c o m p l e x e s of m a c r o c y c l i c tetrathioether l i g a n d s . The

rhodium (III)

complexes

1,4,8,11-tetrathiacyclotetradecane

of

the

1,4,8,11-tetrathiacyclopentadecane

reported (4).

tetrathioethers

a n d 13,14-benzo-

( T T X , Structure II)

I

yielding

macrocyclic

( T T P , Structure I)

were

recently

II

T h e tetradentate l i g a n d s c o o r d i n a t e i n a f o l d e d f a s h i o n

cis-diacido

octahedral

complexes,

e.g.

Rh

n l

(TTP)Cl

2

+

.

The

m a n y c o n v i n c i n g demonstrations t h a t m a c r o c y c l i c l i g a n d s f a c i l i t a t e the s t a b i l i z a t i o n of extreme o x i d a t i o n states (e.g.

Ref. 5 a n d references c i t e d

t h e r e i n ) s t r o n g l y s u p p o r t t h e p o s s i b i l i t y that l i g a n d s of structures I a n d I I w o u l d f o r m stable r h o d i u m ( I )

d e r i v a t i v e s . T h i s is i n d e e d the case,

a n d c h e m i c a l or e l e c t r o c h e m i c a l r e d u c t i o n of the c o r r e s p o n d i n g r h o d i u m (III)

c o m p l e x leads to t h e f o u r - c o o r d i n a t e c a t i o n i c r h o d i u m ( I )

Rh(TTP)

+

and R h ( T T X )

+

species

w h i c h w e r e i s o l a t e d as the B ( C H ) " , C K V , 6

5

4

B F ~ , P F , N C S " , I", a n d B r " salts of T T P a n d as the P F " salt of T T X . 4

6

6

T h e a d d u c t f o r m a t i o n a n d o x i d a t i v e a d d i t i o n reactions of

Rh(TTP)

w e r e i n v e s t i g a t e d w i t h a r a n g e of p o t e n t i a l reactants i n c l u d i n g 0 , 2

+

S0 , 2

C O , B F , C H , tetracyanoethylene, H , Ρφ , alkyl, acyl, a n d arolyl halides, 3

2

4

2

3

N O , a n d strong B r 0 n s t e d acids. +


360

INORGANIC COMPOUNDS W I T H UNUSUAL PROPERTIES

Experimental


General Procedure. A l l m a n i p u l a t i o n s i n v o l v i n g complexes of r h o d i u m ( I ) w e r e d o n e i n a v a c u u m atmospheres g l o v e box e q u i p p e d w i t h a n efficient p u r i f i c a t i o n t r a i n , or u n d e r n i t r o g e n , unless n o t e d o t h e r w i s e . Reagents. S t a n d a r d r e a g e n t g r a d e m a t e r i a l s w e r e u s e d w h e n p o s s i b l e without further purification. Dichloromethane, benzene, methanol, a n d s p e c t r o g r a d e n i t r o m e t h a n e w e r e d r i e d over m o l e c u l a r sieves ( L i n d e ) . A c e t o n i t r i l e a n d d i e t h y l ether w e r e d r i e d over c a l c i u m h y d r i d e . A n y p e r o x i d e present i n the ether was r e m o v e d b y p a s s i n g i t t h r o u g h a c o l u m n of a l u m i n a ; this w a s f o l l o w e d b y t e s t i n g w i t h K I . I n a l l reactions i n v o l v i n g r h o d i u m ( I ) , i t is i m p e r a t i v e that the solvents b e b o t h o x y g e n - a n d p e r o x i d e - f r e e ; therefore a l l solvents w e r e r o u t i n e l y p u r g e d 1 5 - 2 0 m i n w i t h n i t r o g e n to r e m o v e a n y d i s s o l v e d oxygen. Physical Measurements. Analyses were performed b y Galbraith L a b o r a t o r i e s , Inc., K n o x v i l l e , T e n n . , a n d b y A l f r e d B e r n h a r d t M i k r o analytisches L a b o r a t o r i u m , 5251 E l b a c h i i b e r E n g e l s k i r c h e n , W e s t G e r m a n y . C o n d u c t a n c e was m e a s u r e d o n 1 0 " - 1 0 " M solutions u s i n g a n I n d u s t r i a l I n s t r u m e n t s m o d e l R C 16B c o n d u c t i v i t y b r i d g e . D r i e d s p e c t r o g r a d e n i t r o m e t h a n e a n d d r i e d a c e t o n i t r i l e w e r e the solvents. 3

4

IR Spectra. A P e r k i n - E l m e r 337 r e c o r d i n g I R s p e c t r o p h o t o m e t e r was u s e d r o u t i n e l y to o b t a i n I R spectra at 4 0 0 0 - 4 0 0 c m " . F o r this r e g i o n , t h e samples w e r e p r e p a r e d as N u j o l m u l l s pressed b e t w e e n p o t a s s u m b r o m i d e plates or as solutions i n m a t c h e d l i q u i d cells ( 0 . 1 - m m p a t h l e n g t h ) w i t h p o t a s s i u m b r o m i d e w i n d o w s . T h e f a r - I R spectra w e r e o b t a i n e d o n a P e r k i n - E l m e r 457 g r a t i n g I R spectrophotometer. S a m p l e s for this r e g i o n w e r e p r e p a r e d as N u j o l m u l l s a n d pressed b e t w e e n c e s i u m i o d i d e plates. 1

Electronic Spectra. V i s i b l e , n e a r - I R , a n d U V a b s o r p t i o n s p e c t r a w e r e o b t a i n e d w i t h a C a r y m o d e l 1 4 R r e c o r d i n g spectrophotometer. S o l u t i o n spectra w e r e r u n i n m a t c h i n g 1-cm q u a r t z cells. N M R Spectra. T h e N M R spectra of l i g a n d s a n d complexes w e r e r u n o n a V a r i a n Associates H A - 6 0 or Jeolco M H - 1 0 0 spectrometer. T h e solvents u s e d w e r e the d e u t e r o d e r i v a t i v e s of the solvents n e e d e d to dissolve the c o m p o u n d s b e i n g s t u d i e d . T e t r a m e t h y l s i l a n e w a s the i n t e r nal standard. Mass Spectra. M a s s s p e c t r a w e r e o b t a i n e d w i t h a n Α Ε Ι M S - 9 0 2 mass s p e c t r o m e t e r o p e r a t i n g at ca. 8 or 70 e V . Electrochemistry. C o n v e n t i o n a l p o l a r o g r a p h y a n d c y c l i c v o l t a m metry were performed w i t h an Indiana Instrument and C h e m i c a l m o d e l O R N L - 1 9 8 8 A controlled-potential and derivative voltammeter. C u r r e n t p o t e n t i a l curves w e r e r e c o r d e d o n a H e w l e t t - P a c k a r d / M o s e l e y X - Y r e c o r d e r . A l l measurements w e r e m a d e i n a c e t o n i t r i l e i n a v a c u u m atmospheres g l o v e b o x u n d e r n i t r o g e n w i t h t e t r a - n - b u t y l a m m o n i u m tetrafluoroborate as s u p p o r t i n g electrolyte. E x p e r i m e n t a l r u n s w e r e m a d e u s i n g a t h r e e - c o m p a r t m e n t Η-type p o l a r o g r a p h i c c e l l . A r o t a t i n g p l a t i n u m w i r e s e r v e d as the w o r k i n g electrode, a n d the reference e l e c t r o d e w a s a c h l o r i d e - c o a t e d s i l v e r w i r e ( + 0 . 3 0 V vs. A g / A g , 0 . 1 M ) . F o r c o n t r o l l e d p o t e n t i a l electrolysis, a B r i n k m a n - W e n k i n g m o d e l 6 8 F F 0.5 e l e c t r o n i c potentiostate w a s u s e d . +



29.

LEMKE

Macrocyclic

ET AL.

Tetradentate

361

Thioethers

Synthesis o f L i g a n d s . T E T R A D E N T A T E L I G A N D S . T h e Hgands 1,4,8,11tetrathiacyclotetradecane( T T P ) a n d 13,14-benzo-l,4,8,ll-tetrathiacyclop e n t a d e c a n e ( T T X ) w e r e s y n t h e s i z e d as r e p o r t e d p r e v i o u s l y ( 4 ) . 1 , 1 , 1 - T R I S ( M E T H Y L T H I O M E T H Y L ) E T H A N E . I n 500 m l o f e t h a n o l u n d e r n i t r o g e n w a s d i s s o l v e d 6.9 g ( 0.3 m o l e ) f r e s h l y c u t s o d i u m m e t a l . M e t h y l m e r c a p t a n ( M a t h e s o n ) was b u b b l e d i n t o the s o l u t i o n u n t i l n o m o r e gas s e e m e d to dissolve (ca. 45 m i n . ) . T h e r e s u l t i n g s o l u t i o n w a s h e a t e d to reflux, a n d 31 g (0.1 m o l e ) l , l , l - t r i s ( b r o m o m e t h y l ) e t h a n e p r e p a r e d b y the v o n D o e r i n g a n d L e v y m e t h o d (6) w a s a d d e d d r o p w i s e . T h e m i x t u r e w a s refluxed a n a d d i t i o n a l 2 hrs, t h e n c o o l e d a n d filtered. T h e solvent w a s r e m o v e d , l e a v i n g a colorless l i q u i d w h i c h w a s d i s t i l l e d ( b p 9 3 - 9 5 ° C / 0 . 5 m m ) to y i e l d 1 5 . 6 g of the d e s i r e d p r o d u c t ( 7 4 % ) . A n a l , c a l c d f o r C H S : C 45.66, H 8.62, S 45.72; f o u n d : C 45.62, M 8.61, S 45.60. T h e mass s p e c t r u m has a p a r e n t p e a k m/e = 210 (theor., 2 1 0 ) . T h e N M R s p e c t r u m has singlets at τ = 8.90 ( a r e a = 3 ) , τ = 7.85 ( a r e a = 9 ) , a n d = 7.33 ( a r e a = 6 ) . 2 , 6 - D I T H I A H E P T A N E . This compound was previously prepared b y an other m e t h o d ( 7 ) . I n 500 m l e t h a n o l u n d e r n i t r o g e n was d i s s o l v e d 13.8 g ( 0 . 6 m o l e ) freshly cut s o d i u m m e t a l . T o this s o l u t i o n , 3 2 . 4 g ( 0 . 3 m o l e ) 1 , 3 - p r o p a n e d i t h i o l ( A l d r i c h ) w a s a d d e d d r o p w i s e d u r i n g 10 m i n , a n d the m i x t u r e was h e a t e d to reflux for 30 m i n . T h e r e s u l t i n g s o l u t i o n w a s c o o l e d to r o o m t e m p e r a t u r e , a n d 85.1 g (0.6 m o l e ) m e t h y l i o d i d e ( B a k e r ) was a d d e d d r o p w i s e d u r i n g 20 m i n . T h e m i x t u r e w a s t h e n h e a t e d to reflux a n d was refluxed 12 hrs. A f t e r c o o l i n g to r o o m t e m p e r a t u r e , the e t h a n o l was r e m o v e d o n a flash evaporator. T h e r e s u l t i n g o i l w a s filtered to r e m o v e the s o d i u m i o d i d e , a n d i t was t h e n d i s t i l l e d ( b p 7 7 - 7 8 ° C / 0 . 5 m m ) to y i e l d 20.0 g of the d e s i r e d p r o d u c t ( 4 9 % ). T h e mass s p e c t r u m has a p a r e n t p e a k at m/e = 136 (theor., 1 3 6 ) . T h e N M R s p e c t r u m has a q u i n t e t at τ = 8.90 ( a r e a = 2 ) , a singlet at τ = 7.90 ( a r e a = 6 ) , a n d a t r i p l e t at τ = 7.42 ( area = 4 ). 8

1 8

3

T

T R I C H L O R O [ 1 , 1 , 1 - T R I S ( M E T H Y L T H I O M E T H Y L ) E T H A N E ] R H O D I U M ( I I I ).

O n e g r a m of R h C l · 3 H 0 d i s s o l v e d i n 100 m l hot e t h a n o l was a d d e d d r o p w i s e for 1 h r to a r a p i d l y r e f l u x i n g s o l u t i o n of 2 g 1 , l , l - t r i s ( m e t h y l t h i o m e t h y l ) ethane i n 300 m l e t h a n o l . B y t h e e n d of this t i m e , t h e p r o d u c t h a d b e g u n to p r e c i p i t a t e as a l i g h t y e l l o w p o w d e r . A p p r o x i m a t e l y 200 m l e t h a n o l w a s r e m o v e d o n a flash evaporator, a n d d i e t h y l ether was a d d e d to c o m p l e t 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 p r o d u c t was c o l l e c t e d o n a filter frit, w a s h e d w i t h d i e t h y l ether, a n d d r i e d i n a v a c u u m o v e n o v e r n i g h t at 6 0 ° C . T h e m o l a r c o n d u c t a n c e ( C H N 0 ) is 11 c m / o h m m o l e w h i c h is i n d i c a t i v e of a nonelectrolyte. T h e c o m p l e x is s p a r i n g l y s o l u b l e in methanol, ethanol, acetonitrile, and nitromethane. trans-DiCHLORoms ( 2 , 6 - D I T H I A H E P T A N E ) R H O D I U M ( III CHLORIDE. A h o t e t h a n o l i c s o l u t i o n of 1 g R h C l · 3 H 0 w a s a d d e d d r o p w i s e d u r i n g 1 h r to a r e f l u x i n g s o l u t i o n of 1.5 g 2,6-dïthiaheptane i n 200 m l e t h a n o l . T h e r e s u l t i n g b r i g h t o r a n g e s o l u t i o n was c o n c e n t r a t e d t o a p p r o x i m a t e l y 30 m l ; c o l d d i e t h y l ether was t h e n a d d e d u n t i l t h e s o l u t i o n b e c a m e c l o u d y . A f t e r storage o v e r n i g h t i n the r e f r i g e r a t o r at 0 ° C , b r i g h t o r a n g e crystals of the c o m p l e x w e r e o b t a i n e d . T h e p r o d u c t w a s c o l l e c t e d , w a s h e d w i t h d i e t h y l ether, a n d d r i e d i n a v a c u u m desiccator at r o o m t e m p e r a t u r e . C r y s t a l s of the c o m p l e x c o n t a i n w a t e r as was d e m o n s t r a t e d b y t h e s t r o n g O H - O H s t r e t c h i n g b a n d i n the I R s p e c t r u m . 3

2

8

2

2

)

3

2


362

INORGANIC

COMPOUNDS

WITH

UNUSUAL

PROPERTIES

ffYZnS-DlCHLOROBIS ( 2,5-DITHIAHEXANE ) RHODIUM ( I I I ) CHLORIDE, [ R H -

( D T H ) C L ] C L . T h i s c o m p l e x w a s p r e p a r e d b y the W a l t o n m e t h o d ( J ) b y a d d i n g excess 2,5-dithiahexane ( K a n d K ) to a r e f l u x i n g s o l u t i o n of R h C l , · 3 H . O . T h e i n i t i a l y e l l o w p r e c i p i t a t e of the d i m e r d i s s o l v e d l e a v i n g a b r i g h t y e l l o w s o l u t i o n f r o m w h i c h the b r i g h t y e l l o w p r o d u c t w a s i s o l a t e d b y flashing off the e t h a n o l a n d i n d u c i n g c r y s t a l l i z a t i o n b y a d d i n g d i e t h y l ether. T h e I R s p e c t r u m of the p r o d u c t is i d e n t i c a l to t h a t described by Walton. 2

2

{

PREPARATION OF T H E RHODIUM(I)

1,4,8,11-TETRATHIA-

COMPLEXES OF

A s o l u t i o n of 0.5 g [ R h ( T T P ) C l ] C l i n 50 m l d r i e d , d e a e r a t e d m e t h a n o l was p r e p a r e d i n a n i n e r t a t m o s p h e r e g l o v e b o x or u n d e r a p u r g e of n i t r o g e n . T o this s o l u t i o n was a d d e d 0.25 g (excess) sodium borohydride dissolved i n ~ 5 m l methanol. T h e solution turned i m m e d i a t e l y f r o m b r i g h t y e l l o w to r e d d i s h g o l d . A s o l u t i o n of 2 - 3 g ( e x c e s s ) of the a p p r o p r i a t e salt ( L i C 1 0 , L i B F , N H P F , NH I, N H S C N or L i B r ) d i s s o l v e d i n m e t h a n o l was t h e n a d d e d . W i t h C 1 0 " , B F " , P F " , a n d Γ , b r i g h t g o l d e n crystals of the c o m p l e x f o r m e d ; for t h e S C N " a n d B r " d e r i v a t i v e s , t h e v o l u m e was r e d u c e d to about 15 m l a n d c r y s t a l l i z a t i o n w a s i n d u c e d b y the a d d i t i o n of d i e t h y l ether. T h e p r o d u c t w a s c o l l e c t e d o n a filter f r i t ; it was w a s h e d w i t h a s m a l l a m o u n t of d r y , p e r o x i d e - f r e e , d e a e r a t e d d i e t h y l ether a n d d r i e d b y p u m p i n g o n a v a c u u m l i n e i n t h e g l o v e box.


CYCLOTETRADECANE.

2

4

4

4

G

4

4

4

4

e

(13,14-BENZO-1,4,8,11-TETRATHIACYCLOPENTADECANE)RHODIUM(I)

[ R H ( T T X ) ] P F . T O a s o l u t i o n of 0.5 g [ R h ( T T X ) C 1 ] C 1 · 3 . 5 H . O i n 50 m l d r y , d e a e r a t e d m e t h a n o l w a s a d d e d 0.15 g s o d i u m b o r o h y d r i d e d i s s o l v e d i n 5 m l m e t h a n o l . E x c e s s ( 2 - 3 g ) N H P F d i s s o l v e d i n 10 m l m e t h a n o l was t h e n a d d e d to the g o l d s o l u t i o n . T h e b r o w n - g o l d p r o d u c t c r y s t a l l i z e d out of s o l u t i o n a n d was c o l l e c t e d o n a filter f r i t a n d d r i e d o n a v a c u u m l i n e i n the g l o v e box. R e a c t i o n o f [ R h ( T T P ) ] w i t h S m a l l C ov a l e n t M o l e c u l e s . S U L F U R HEXAFLUOROPHOSPHATE,

0

2

4

G

+

( 1,4,8,11-TETRATHIACYCLOTETRADECANE )RHODIUM ( I )

DIOXIDE

PERCHLO-

R A T E , [ R h ( T T P ) S 0 ] C 1 0 . T o a s o l u t i o n of 0.3 g [ R h ( T T P ) C l ] C l i n 30 m l m e t h a n o l , 0.15 g s o d i u m b o r o h y d r i d e i n 5 m l m e t h a n o l w a s a d d e d u n d e r a n i t r o g e n p u r g e to g i v e a g o l d s o l u t i o n c o n t a i n i n g [ R h ( T T P ) ] . S u l f u r d i o x i d e ( C . P . M a t h e s o n ) was 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 together w i t h t h e n i t r o g e n p u r g e for 3 - 5 m i n . T o the r e s u l t i n g b r i g h t y e l l o w s o l u t i o n was t h e n a d d e d 2 g L i C 1 0 d i s s o l v e d i n 10 m l m e t h a n o l . T h e b r i g h t y e l l o w s o l i d w h i c h f o r m e d i m m e d i a t e l y was c o l l e c t e d o n a filter frit u n d e r n i t r o g e n a n d d r i e d i n a v a c u u m desiccator at r o o m temperature. REACTION OF [RH(TTP)] W I T H O X Y G E N . A s o l u t i o n of [Rh(TTP)] i n m e t h a n o l was p r e p a r e d as d e s c r i b e d a b o v e b y the r e d u c t i o n of [ R h ( T T P ) C 1 ] C 1 i n m e t h a n o l w i t h s o d i u m b o r o h y d r i d e . U p o n exposure to a i r for 3 - 5 m i n , t h e g o l d s o l u t i o n t u r n e d d e e p b l u e i n i t i a l l y , a n d t h e n i t r a p i d l y b e c a m e d e e p r e d - b r o w n . A t this p o i n t , L i C 1 0 dissolved i n m e t h a n o l was a d d e d to p r e c i p i t a t e the p r o d u c t w h i c h w a s o b t a i n e d as a b r o w n a m o r p h o u s s o l i d . T h e m o l a r c o n d u c t a n c e ( C H 3 N O 0 ) is 83 c m / o h m mole. 2

4

2

+

4

+

2

4

2

TETRACYANOETHYLENE(1,4,8,11-TETRATHIACYCLOTETRADECANE)RHODIUM(I)

[ R H ( T T P ) C N ] P F . T O a s o l u t i o n of i n 50 m l of a c e t o n i t r i l e w a s a d d e d 0.1 g t e t r a -

HEXAFLUOROPHOSPHATE,

0.35 g [ R h ( T T P ) ] P F

e

6

4

6


29.

LEMKE

ET

Macrocyclic

AL.

Tetradentate

Thioethers

363

c y a n o e t h y l e n e ( A l d r i c h ) d i s s o l v e d i n 1 0 m l ocetonitrile. T h e s o l u t i o n t u r n e d i m m e d i a t e l y f r o m g o l d to b r i g h t o r a n g e - y e l l o w , a n d a b r i g h t o r a n g e - y e l l o w s o l i d b e g a n f o r m i n g . T h e v o l u m e of the s o l u t i o n w a s r e d u c e d to 2 0 m l to c o m p l e t e p r e c i p i t a t i o n of the p r o d u c t w h i c h w a s c o l l e c t e d , w a s h e d w i t h d i e t h y l ether, a n d d r i e d . BORON TRIPLUORIDE(1,4,8,11-TETRATHIACYCLOTETRADECANE)RHODIUM(I)

[ B F R h ( T T P ) ] P F · C H C N . T o a s o l u t i o n of 0 . 3 g [ R h ( T T P ) ] P F i n 4 0 m l acetonitrile was a d d e d 0 . 1 5 m l freshly d i s t i l l e d a n d d e a e r a t e d b o r o n t r i f l u o r i d e etherate ( B a k e r ) . A s the s o l u t i o n was s t i r r e d 5 m i n , its color c h a n g e d f r o m g o l d to p a l e y e l l o w . W h e n the v o l u m e was r e d u c e d to 1 5 m l , a p a l e y e l l o w s o l i d b e g a n p r e c i p i t a t i n g , a n d s m a l l amounts of d i e t h y l ether w e r e a d d e d for 1 0 - 1 5 m i n to c o m p l e t e p r e c i p i t a t i o n . T h e p r o d u c t was i s o l a t e d as a l i g h t y e l l o w a m o r p h o u s powder.


3

6

3


6

NITROSYL(1,4,8,11-TETRATHIACYCLOTETRADECANE)RHODIUM(III)

TETRA-

[ R h ( T T P ) N O ] ( B F ) . T o a s o l u t i o n of 0 . 2 5 g [ R h ( T T P ) ] B F i n 4 0 m l a c e t o n i t r i l e , a s o l u t i o n of 0 . 1 g (excess) n i t r o s o n i u m t e t r a fluoroborate ( A l d r i c h ) d i s s o l v e d i n 5 m l a c e t o n i t r i l e was a d d e d d r o p wise. D u r i n g the a d d i t i o n , the s o l u t i o n t u r n e d f r o m the g o l d e n c o l o r of [ R h ( T T P ) ] to a b r i g h t green. T h e v o l u m e of the s o l u t i o n w a s t h e n r e d u c e d to a p p r o x i m a t e l y 1 0 - 1 5 m l , a n d s m a l l aliquots of d i e t h y l ether w e r e a d d e d for 3 0 m i n . T h e b r i g h t green m i c r o c r y s t a l l i n e p r o d u c t w a s c o l l e c t e d , w a s h e d w i t h d i e t h y l ether, a n d d r i e d b y p u m p i n g o n a v a c u u m line.

FLUOROBORATE,

4

2

4

+

A C E T Y L C H L O R O ( 1 , 4 , 8 , 1 1 - T E T R A T H I A C Y C L O T E T R A D E C A N E ) R H O D I U M ( III

)

[ C H C O ) R h ( T T P ) C l ] P F . T o a s o l u t i o n of 0 . 3 g [ R h ( T T P ) ] P F i n 5 0 m l acetonitrile was a d d e d 0 . 1 m l ( 0 . 0 9 g ) a c e t y l chloride ( M a l l i n c k r o d t ) (excess). T h e solution turned immediately f r o m g o l d to p a l e y e l l o w . T h e p r o c e d u r e d e s c r i b e d a b o v e was u s e d to isolate a p a l e y e l l o w m i c r o c r y s t a l l i n e s o l i d . HEXAFLUOROPHOSPHATE,

3

6

G

I O D O M E T H Y L ( 1 , 4 , 8 , 1 1 - T E T R A T H I A C Y C L O T E T R A D E C A N E ) R H O D I U M ( III

)

[ C H R h ( T T P ) I ] C 1 0 . T h e a d d i t i o n of 0 . 1 5 g s o d i u m b o r o h y d r i d e i n 5 m l m e t h a n o l to a s o l u t i o n of 0 . 3 g [ R h ( T T P ) C l ] C l i n 4 0 m l u n d e r n i t r o g e n gave a g o l d s o l u t i o n c o n t a i n i n g [ R h ( T T P ) ] When 2 m l (excess) freshly d i s t i l l e d m e t h y l i o d i d e ( B a k e r ) was a d d e d , the s o l u t i o n b e c a m e y e l l o w i s h g o l d ; the a d d i t i o n of 2 g L i C 1 0 d i s s o l v e d i n 1 0 m l m e t h a n o l c l o u d e d the s o l u t i o n . A s the v o l u m e was r e d u c e d , the p r o d u c t c r y s t a l l i z e d o u t as a y e l l o w i s h g o l d s o l i d ; i t was c o l l e c t e d o n a filter f r i t a n d d r i e d i n a v a c u u m desiccator at r o o m t e m p e r a t u r e .

PERCHLORATE,

8

4

2

+

4

H Y D R I D O ( 1 , 4 , 8 , 1 1 - T E T R A T H I A C Y C L O T E T R A D E C A N E ) R H O D I U M ( III )

TETRA-

[HRh(TTP)](BR )o. T o a s o l u t i o n of 0 . 3 5 g [ R h ( T T P ) ] B F i n 4 0 m l n i t r o m e t h a n e was a d d e d 0 . 2 m l 4 8 % aqueous H B F ( A l f a ) f r o m a fresh sample. T h e s o l u t i o n t u r n e d s l o w l y f r o m g o l d to g r e e n i s h y e l l o w ; its v o l u m e was r e d u c e d to 1 0 m l , a n d s m a l l amounts of b e n z e n e w e r e a d d e d for 1 5 m i n to i n d u c e c r y s t a l l i z a t i o n . T h e p r o d u c t was isolated as a greenish y e l l o w m i c r o c r y s t a l l i n e s o l i d . T h e I R s p e c t r u m ( N u j o l ) has a w e a k b a n d at 2 2 2 0 c m " w h i c h is assigned to the R h - H s t r e t c h i n g f r e q u e n c y . T h e m o l o r c o n d u c t a n c e ( C H C N ) is 2 7 9 c m / o h m m o l e . ( N o t e : w h e n aqueous H B F of i n d e t e r m i n a t e age was u s e d , i l l defined p r o d u c t s w e r e o b t a i n e d w h i c h m a y h a v e r e s u l t e d f r o m t h e o x i d a t i o n of t h e r h o d i u m ( I ) b y contaminants s u c h as H F ) .

FLUOROBORATE,

4

4

4

1

3

4


2

364

INORGANIC

Œ-ALLYLCHLORO-(OR

COMPOUNDS

WITH

UNUSUAL

PROPERTIES

BROMO ) - ( 1,4,8,11-TETRATHIACYCLOTETRADECANE)-

[ ( a - C H ) R h ( T T P ) C l ] P F . To a s o l u t i o n of 0 . 4 g [ R h ( T T P ) ] P F i n 5 0 m l a c e t o n i t r i l e was a d d e d 0 . 1 m l a l l y l c h l o r i d e ( or a l l y l b r o m i d e ). T h e s o l u t i o n t u r n e d i m m e d i a t e l y f r o m g o l d to a v e r y p a l e y e l l o w . T h e v o l u m e w a s r e d u c e d to 1 5 m l , a n d s m a l l a m o u n t s of d i e t h y l ether w e r e a d d e d for 1 5 m i n . T h e p r o d u c t w a s o b t a i n e d as a n off-white p o w d e r w h i c h c o u l d b e 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 - e t h e r solutions.

RHODIUM(III)


3

5

6

6

t

rans-DiCHLORO

( 1,4,8,11-TETRATHIACYCLOTETRADECANE )RHODIUM ( III )

[ R h ( T T P ) C l ] P F . A n excess of a s a t u r a t e d s o l u t i o n of c h l o r i n e i n a c e t o n i t r i l e w a s a d d e d to a s o l u t i o n of 0 . 3 5 g [ R h ( T T P ) ] P F i n 5 0 m l a c e t o n i t r i l e . A s the s o l u t i o n was s t i r r e d at r o o m t e m p e r a t u r e for 4 5 m i n , its c o l o r c h a n g e d f r o m g o l d to b r i g h t y e l l o w . T h e excess c h l o r i n e was r e m o v e d b y p u m p i n g o n a v a c u u m l i n e , a n d the v o l u m e of the s o l u t i o n was r e d u c e d to 1 5 m l . B r i g h t y e l l o w m i c r o c r y s t a l s of the p r o d u c t f o r m e d w h e n d i e t h y l ether was a d d e d s l o w l y . T h e p r o d u c t w a s c o l l e c t e d , w a s h e d w i t h d i e t h y l ether, a n d d r i e d b y p u m p i n g o n a v a c u u m line. HEXAFLUOROPHOSPHATE,

2

6


6

B E N Z O Y L C H L O R O ( 1,4,8,11-TETRATHIACYCLOTETRADECANE )RHODIUM(III)

[ C H C O ) R h ( T T P ) C l ] P F . Freshly distilled b e n z o y l c h l o r i d e ( B a k e r ) ( 0 . 1 m l , 0 . 1 1 g ) was a d d e d d r o p w i s e to a s o l u t i o n of 0 . 3 g [ R h ( T T P ) ] P F i n 5 0 m l a c e t o n i t r i l e . A s the s o l u t i o n w a s s t i r r e d for 5 m i n , its c o l o r c h a n g e d f r o m g o l d to p a l e y e l l o w . A f t e r the v o l u m e was r e d u c e d to 1 5 m l , s m a l l amounts of d i e t h y l ether w e r e a d d e d to c r y s t a l l i z e t h e p r o d u c t . T h e p r o d u c t w a s o b t a i n e d as a p a l e y e l l o w amorphous p o w d e r w h i c h c o u l d be recrystallized from acetonitrile b y the s l o w a d d i t i o n of d i e t h y l ether. tfatis-DiiOOO ( 1 , 4 , 8 , 1 1 - T E T R A T H I A C Y C L O T E T R A D E C A N E ) R H O D I U M ( I I I ) H E X A F L U O R O P H O S P H A T E , [ R h ( T T P ) I ] P F . T o a s o l u t i o n of 0 . 4 g [ R h ( T T P ) ] P F i n 4 0 m l a c e t o n i t r i l e was a d d e d 0 . 1 g i o d i n e d i s s o l v e d i n 1 0 m l a c e t o n i t r i l e . T h e s o l u t i o n was s t i r r e d 6 hrs at r o o m t e m p e r a t u r e w h i l e its color t u r n e d g r a d u a l l y f r o m g o l d to b r i g h t orange. R e d u c i n g the v o l u m e of the s o l u t i o n to 1 0 - 1 5 m l a n d a d d i n g s m a l l a l i q u o t s of d i e t h y l ether for 3 0 m i n g a v e b r i g h t orange crystals of t h e d e s i r e d p r o d u c t . T h e p r o d u c t was c o l l e c t e d , w a s h e d w i t h d i e t h y l ether, a n d d r i e d as described previously.


6

5

6

6

2

e

6

B E N Z Y L B R O M O ( 1,4,8,11-TETRATHIACYCLOTETRADECANE )RHODIUM ( III )

[C H CH Rh(TTP)Br]PF . Benzyl bromide ( 0 . 1 1 m l , 0 . 1 5 g ) was a d d e d d r o p w i s e to a s o l u t i o n of 0 . 3 5 g [ R h ( T T P ) ] P F i n 4 0 m l a c e t o n i t r i l e . T h e c o l o r of the s o l u t i o n c h a n g e d i m m e d i a t e l y f r o m g o l d to b r i g h t y e l l o w . R e d u c i n g the v o l u m e to 1 0 m l a n d s l o w l y a d d i n g s m a l l p o r t i o n s of d i e t h y l ether y i e l d e d b r i g h t y e l l o w crystals o f the d e s i r e d c o m p l e x w h i c h w e r e c o l l e c t e d , w a s h e d w i t h d i e t h y l ether, a n d d r i e d as d e s c r i b e d p r e v i o u s l y . REACTION OF [ R h ( T T P ) P F W I T H C H S 0 C 1 . Methane sulfonyl c h l o r i d e ( B a k e r ) was freshly d i s t i l l e d b e f o r e use. T o a s o l u t i o n of 0 . 3 g [ R h ( T T P ) ] P F i n 5 0 m l a c e t o n i t r i l e was a d d e d 0 . 2 m l C H S 0 C 1 . T h e color of the s o l u t i o n c h a n g e d i m m e d i a t e l y f r o m g o l d to a v e r y d e e p r e d . T h e v o l u m e w a s r e d u c e d to 1 0 m l , a n d s m a l l amounts of b e n z e n e w e r e a d d e d u n t i l the s o l u t i o n b e c a m e c l o u d y . W h e n t h e s o l u t i o n w a s a l l o w e d to sit 2 0 m i n , a s m a l l a m o u n t of a d a r k r e d - b r o w n p o w d e r f o r m e d . T h e HEXAFLUOROPHOSPHATE,

6

5

2

e

6

6

e

3

2

3

2


29.

LEMKE

ET

AL.

Macrocyclic

Tetradentate

365

Thioethers

p o w d e r was collected, washed w i t h benzene, a n d d r i e d on a v a c u u m l i n e . T h e I R s p e c t r u m of t h e p o w d e r has n o b a n d s a t t r i b u t a b l e to t h e S 0 g r o u p . T h e E S R s p e c t r u m of the i n i t i a l d e e p r e d s o l u t i o n i n d i c a t e s no p a r a m a g n e t i c species. A n a l y s i s of the p r o d u c t is most consistent w i t h a d i c h l o r o - r h o d i u m ( I I I ) c o m p l e x . A n a l . : c a l c d for [ R h ( C i H o S 4 ) C l ] P F C H C N : C 22.93, H 3.68, S 20.41, R h 16.38; f o u n d : C 22.85, H 3.94, S 20.56, R h 16.38. REACTION OF [Rh(TTP)] W I T H H . H y d r o g e n ( C . P. Burdett) was b u b b l e d v i g o r o u l y t h r o u g h a s o l u t i o n of 0.45 g [ R h ( T T P ) ] P F i n 50 m l a c e t o n i t r i l e for 30 m i n ; there was n o c o l o r change. T h e I R s p e c t r u m of the s o l u t i o n has no bands t h a t are a t t r i b u t a b l e to a R h - H s t r e t c h i n g f r e q u e n c y . W h e n h y d r o g e n w a s b u b b l e d t h r o u g h a s o l u t i o n of [ R h ( T T P ) ] P F for 4 - 5 hrs, the c o l o r g r a d u a l l y b e c a m e b l u i s h b e c a u s e of the f o r m a t i o n of the R h ( I I ) species, [ R h ( T T P ) ] , p r e s u m a b l y as the r e s u l t of traces of o x y g e n i m p u r i t i e s i n the h y d r o g e n . T h i s r e a c t i o n w a s n o t i n v e s t i g a t e d f u r t h e r . T h e R h ( I I ) species are the subject of a separate report. C A T A L Y T I C E X P E R I M E N T S W I T H [ R h ( T T P ) ] . A n attempt was made to c a t a l y z e the hydrogénation of m a l e i c a c i d w i t h [ R h ( T T P ) ] B F u s i n g r e p o r t e d ( l i t e r a t u r e ) c o n d i t i o n s . A s o l u t i o n of 0.171 g [ R h ( T T P ) ] B F ( 0 . 0 0 7 5 M ) a n d 0.290 g m a l e i c a c i d ( 0 . 0 5 M ) i n 50 m l d i m e t h y l a c e t a m i d e w a s h e a t e d to 60 ° C , a n d t h e n h y d r o g e n w a s b u b b l e d v i g o r o u s l y t h r o u g h the s o l u t i o n 1 h r at either 6 0 ° or ca. 2 5 ° C . D u r i n g this t i m e , n o c o l o r c h a n g e was observed. T h e v o l u m e was r e d u c e d to 10 m l b y d i s t i l l i n g off the D M A , a n d a n N M R s p e c t r u m was o b t a i n e d ; no traces of s u c c i n i c a c i d are d e t e c t e d i n the N M R s p e c t r u m . 2

0

6

2

2

3

+

2


6

6

+ 2

+

4

4

Results

and

Discussion

F o r m a t i o n a n d C h a r a c t e r i z a t i o n o f the R h ( I )

Complexes.

T h e ex-

t r e m e difference b e t w e e n the b e h a v i o r of m a c r o c y c l i c l i g a n d d e r i v a t i v e s [ R h ( T T P ) C l ] C l a n d [ R h ( T T X ) C l ] C l a n d that of r h o d i u m c o m p l e x e s 2

2

c o n t a i n i n g a c y c l i c chelate l i g a n d s deserves a d d i t i o n a l emphasis. W e c o n firmed

W a l t o n ' s observations t h a t b o t h c h e m i c a l ( s o d i u m

borohydride)

a n d e l e c t r o c h e m i c a l r e d u c t i o n of [ R h ( D T H ) C l ] C l i n v a r i a b l y leads to 2

2

m i x t u r e s of the free l i g a n d , s o m e c o l l o i d a l r h o d i u m m e t a l , a n d a n u n i d e n t i f i e d d a r k b r o w n species. T o o b v i a t e the p o s s i b i l i t y t h a t the e t h y l e n e b r i d g e i n D T H p r o v i d e s too s m a l l a b i t e for r h o d i u m , t h e r e b y p r o d u c i n g o n l y w e a k c h e l a t i o n , s i m i l a r experiments w e r e c o n d u c t e d w i t h C H S C H 3

CH CH SCH . 2

2

3

H o w e v e r , the r e d u c t i o n of the c o r r e s p o n d i n g

2

Rh(III)

complex w i t h sodium borohydride i n methanol immediately produced

a

b l a c k p r e c i p i t a t e of r h o d i u m m e t a l a n d free l i g a n d . T h e result w a s t h e same

when

reduction was

methyl)ethane}Cl ]. 3

attempted

with

[Rh{l,l,l-tris(methylthio-

I n contrast, [ R h ( T T P ) C l ] C l a n d [ R h ( T T X ) C l ] 2

2

C l c a n be r e d u c e d either e l e c t r o c h e m i c a l l y or c h e m i c a l l y ( s o d i u m b o r o h y d r i d e ) , forming the r h o d i u m ( I ) respectively.

species R h ( T T P )

+

and R h ( T T X ) , +

W i t h the m a c r o c y c l i c l i g a n d d e r i v a t i v e s , w e c o n c l u d e t h a t

t h e k i n e t i c inertness t o w a r d s u b s t i t u t i o n of t h e R h - S b o n d s t h a t derives


366

INORGANIC

COMPOUNDS

WITH

UNUSUAL

Table I.

Elemental Analyses

Calcd, Complex

Η

%

22.89 22.79 25.51

4.32 5.17 4.28

22.92 24.35 27.24

[Rh(TTP)]BF [Rh(TTP)]PF [Rh(TTP)]I [Rh(TTP)]SCN [Rh(TTP)]Br [Rh(TTX)]PF [Rh(TTP)S0,]C10 [Rh(TTP)0,]C10 [Rh(TTP)C«N ]PF [BF Rh (TTP) ] P F · C H C N [Rh(TTP)NO] (BF ), [ (C H C O ) R h (T T P ) Cl] P F [CH.,Rli(TTP)I]C10 [HRh(TTP)] iBF ) [C H- Rh(TTP)Br]PF [C H,,Rli(TTP)Cl]PF [Rh(TTP)Cl ]PF„ [C H,CH,Rh(TTP)Br]PF [ C H , C O R h ( T T P ) C l ] PF« [Rh(TTP)I ]PF

26.21 23.26 24.10 30.76 26.61 31.14 22.45 23.83 29.83 23.05 20.88 24.23 21.56 22.00 24.50 26.24 20.44 29.70 31.08 15.59

4.40 3.90 4.05 4.69 4.47 3.83 3.77 4.01 3.13 3.71 3.51 3.90 3.78 3.88 3.95 4.37 3.43 3.96 3.84 2.62

27.99 24.84 25.74 37.33 28.42 22.17 29.97 25.50 19.90 20.51 22.30 21.56 20.93 23.49 20.12 21.56 21.84 18.66 19.52 16.65

8

1 8

3

5

1 2

2

3

2

2

2

4

6

6

4

4

4

0

3

e

3

4

3

C

4

4

3

2

(

0

: (

6

2

e

e

( !

2

0

Χ

S

[Rh(C H S )Cl ] [ R h ( C H S ) C l ] C l · 2.5H 0 [Rh(TTP)]C10 4


c

PROPERTIES

7.53 ( C l )

25.47(1)

17.95(0) 19.09(0) 8.70 ( Ν ) 2.43 ( Ν ) 5.96 ( C l ) 18.85 ( R h ) 12.54 ( B r ) 5.96 ( C l ) 12.07 ( C l ) 11.62(Br) 5.40(C1) 32.96(1)

f r o m the s t r u c t u r e of the l i g a n d ( δ , 9 ) is r e s p o n s i b l e for the fact t h a t these R h ( I ) complexes c a n be i s o l a t e d . Synthesis of the r h o d i u m ( I )

complexes of T T P a n d T T X is not as

s t r a i g h t f o r w a r d as, for e x a m p l e , t h a t of the R h ( I ) phines.

complexes

S u b s t i t u t i o n reactions, s u c h as t h e r e f l u x i n g of

octadiene) Cl] 2

2

of

phos

[ R h ( 1,5-cyclo-

w i t h T T P , g e n e r a l l y f a i l e d . A l s o the R h ( I I I ) i n R h C l

3

·

3 H 0 is not s i m u l t a n e o u s l y r e d u c e d a n d c h e l a t e d b y T T P ( J O ) . T h e o n l y 2

successful routes that w e f o u n d i n v o l v e t h e r e d u c t i o n of the p r e v i o u s l y c h a r a c t e r i z e d R h ( I I I ) complexes.

V o l t a m m e t r y i n acetonitrile solution

o n [ R h ( T T P ) C l ] C l s h o w e d a single c a t h o d i c process at - 0 . 7 2 V 2

(vs.

A g V A g C l ) w h i c h represents a t w o - e l e c t r o n r e d u c t i o n . S m a l l samples of the R h ( I ) salt w e r e p r e p a r e d b y electrolysis, b u t r e d u c t i o n w i t h s o d i u m b o r o h y d r i d e i n m e t h a n o l w a s u s e d to p r e p a r e most of the salts r e p o r t e d here. T h e a d d i t i o n of v a r i o u s salts to the r e d u c e d solutions l e d to i s o l a t i o n of the series of c o m p o u n d s

R h ( T T P ) X (where

X = B(C H ) - PF ", 6

5

4

C 1 0 - , B r " , Γ, a n d S C N " ) a n d R h ( T T X ) P F . E l e m e n t a l analyses 4

6

r e p o r t e d i n T a b l e I.

T h e molar conductances

are a l l consistent


e

are with

29.

LEMKE

ET

Macrocyclic

AL.

Tetradentate

367

Thioethers

of the N e w R h o d i u m C o m p l e x e s Found, H


c 22.86 22.87 a) 25.40 b) 25.35 25.98 23.18 23.85 30.83 26.11 30.88 22.38 23.39 30.03 23.39 20.51 24.14 21.35 21.97 24.49 26.51 20.41 29.66 31.76 15.46

% X

S

4.24 4.80 4.24 4.19 4.20 3.95 3.86 4.75 4.32 3.79 3.74 3.93 2.96 4.08 3.59 3.72 3.54 3.77 3.98 4.53 3.36 3.94 3.97 2.54

Yield,

%

76 68 60

22.46 24.39 27.16 26.99 27.89 24.57 25.52 36.97 27.99 21.95 30.91 24.31 20.05 20.70 22.39 21.63 21.58 23.32 20.07 22.42 21.63 18.52 19.80 16.55

7.55 ( C l ) 55 65 42 31 30 51 63

25.35(1)

17.84(0) 20.21(0) 8.81 ( N )

71 55

2.27(N) 5.99 ( C l ) 19.09 ( R h ) 12.59 ( B r ) 5.95 ( C l ) 11.99(d) 11.69(Br) 5.36 ( C l ) 33.24(1)

f o r m u l a t i o n as u n i - u n i v a l e n t electrolytes ( T a b l e I I ) s p e c t r a of the salts [ R h ( T T P ) ] X a n d [ R h ( T T X ) ] P F

(11,

The IR

12).

6

r e s e m b l e those of

the R h ( I I I ) complexes ( 4 ) , w h i c h confirms t h e presence of the e s s e n t i a l l y unaltered ligand.

T h e m a i n v a r i a t i o n s a r e a t t r i b u t a b l e to t h e different

anions present a n d to the f a c t that t h e anions r e m a i n u n c o o r d i n a t e d . U n c o o r d i n a t e d B F " has strong b a n d s at 1060 a n d 520 c m , C 1 0 " at 1086 - 1

4

and

620 c m " , a n d P F " at 850 a n d 555 c m . 1

6

4

T h e s p e c t r u m of

- 1

[Rh-

( T T P ) ] S C N shows VCN at 2040 c m " w h i c h is near t h a t f o r K S C N ( 2 0 5 3 1

Table II.

M o l a r C o n d u c t a n c e s o f the R h ( I ) C o m p l e x e s

Complex

Solvent

[Rh (TTP) ] [B ( C H ) ] [Rh(TTP)]BF [Rh(TTP)]PF [Rh(TTP)]C10 [Rh(TTP)]Br [Rh(TTP)]I [Rh(TTP)]SCN [Rh(TTX)]PF 6

4

6

4

6

5

4

CH CH CH CH CH CH CH CH

3

3

3 3 3 3 3 3

N0 CN CN CN CN CN CN CN

\

M>

2

cm /ohm 2

86 135 140 147 132 130 165 150


mole

368

INORGANIC

COMPOUNDS WITH UNUSUAL PROPERTIES

cm" ) and farther i n frequency from N - b o n d e d N C S ( ~ 2065-2100 c m " ) 1

1

and S-bonded N C S (—2100-2127

cm" ).

T h i s supports t h e c o n c l u s i o n

1

t h a t R h ( T T P ) does n o t t e n d to e x p a n d its c o o r d i n a t i o n n u m b e r t o five +

b y c o o r d i n a t i n g to its c o u n t e r i o n . T h e e l e c t r o n i c spectra o f the R h ( I ) complexes are l i s t e d i n T a b l e I I I together w i t h those o f t w o p h o s p h i n e complexes. A c c o r d i n g t o t h e i n t e r pretations of G r a y a n d c o - w o r k e r s ( 1 3 ) , t h e p e r t i n e n t o r d e r i n g o f e n e r g y


Table III.

E l e c t r o n i c S p e c t r a o f Some S q u a r e - P l a n a r R h o d i u m (I) Complexes

Complex

Solvent

[Rh (TTP) ] P F

\ x, nm

CH CN

6

3

[Rh(TTP)]I

3

CH CN

6

3

[ R h (2=phos) ] Β ( C H ) 2

6

5

4

chlorobenzene

α

[Rh(2=phos) ]Cr

EPA

[Rh(2-phos)o]Cr

E P A

2

355 sh

1077

318 sh 293 sh

3736 2418

315 s h 292

3360 6512

352 sh

CH CN

[Rh(TTX)]PF

c

ma

C

985

357 sh

907

324 sh 295 405 341 313 474 405 341 309

3174 6009 6160 6650 10,900 250 4900 4900 8400

470

150

405 314 296 2 h o s is c ; s - [ ( C H 5 ) P C H = C H P ( C H 5 ) ] (W. 2-phos is ( C H 5 ) P C H C H P ( C H 5 ) (18). E P A is a 5:5:2 mixture of diethyl ether-isopentane-ethyl alcohol.

a

= P

6

ft C

5150 9300 8400

6

2

2

6

2

2

2

6

2

levels is p r o b a b l y b < e < a * < a ^ < b ?_ * a n d t h e g r o u n d state c o n f i g u r a t i o n is b e a . T h e lowest v a c a n t o r b i t a l is α π w h i c h is d e r i v e d f r o m v a c a n t l i g a n d o r b i t a l s w i t h π s y m m e t r y . T h u s , the s p e c t r a l b a n d s represent m e t a l - t o - l i g a n d c h a r g e transfer, a n d i t is n o t s u r p r i s i n g that t h e lowest energy b a n d s f o r R h ( T T P ) o c c u r at energies h i g h e r t h a n those f o r t h e R h ( I ) p h o s p h i n e complexes. 2 g ( x y )

g{xz>yz)

lg{

2

2g

4

g

)

2

lg(%

y

y

2

ïg

2(1

+

U s i n g a different o r d e r i n g o f d levels, V a s k a et al. (14) t e n t a t i v e l y assigned t h e first transition o b s e r v e d i n t h e s p e c t r u m o f [ R h ( 2 = p h o s ) ] B ( C H ) at 405 n m as t h e xy-+ x — y transition. T h e spectra of t h e analogous complexes [ C o ( 2 = p h o s ) ] B ( C H ) and [Ir(2=phos) ]B( C H ) h a v e this b a n d a t 730 a n d 525 n m , r e s p e c t i v e l y . T h i s t r a n s i t i o n 2

6

5

4

2

2

2

6

5

6

5

4

4


2

29.

LEMKE

Macrocyclic

ET AL.

Tetradentate

369

Thioethers

is e q u a l to 10 D q , a n d thus the e n e r g y of the t r a n s i t i o n is a measure of the l i g a n d field s t a b i l i z a t i o n energy.

S i n c e the r e a c t i v i t y of the C o ( I ) ,

R h ( I ) , a n d I r ( I ) complexes t o w a r d o x y g e n a n d h y d r o g e n decreased as the e n e r g y of this b a n d i n c r e a s e d , V a s k a suggested

that a correlation

exists a n d that the e l e c t r o n i c spectra of s u c h s q u a r e - p l a n a r d

complexes

8

m a y a i d i n p r e d i c t i n g t h e i r r e l a t e d r e a c t i v i t i e s . H o w e v e r , this m o d e l w o u l d assign a v e r y h i g h l i g a n d field s t r e n g t h to T T P a n d p r e d i c t t h a t thioether complexes than

the

of R h ( I )

corresponding

w o u l d b e m o r e stable a n d less r e a c t i v e

phosphine

complexes.

This

is

contrary

to


experience. Reactivity of R h ( T T P )

The new

toward Nucleophiles.

+

Rh(I)

complexes s h o w no t e n d e n c y to e x p a n d t h e i r c o o r d i n a t i o n n u m b e r s

by

a d d i n g L e w i s bases. N i t r o g e n bases, t r i p h e n y l p h o s p h i n e , c a r b o n m o n o x ide, a n d ethylene a l l f a i l to react w i t h R h ( T T P ) . +

W i t h e t h y l e n e , the

absence of i n t e r a c t i o n w a s c o n f i r m e d b y s o l u t i o n I R s p e c t r a l m e a s u r e ments. A l t h o u g h C O a n d C H 2

4

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

to b a c k b o n d i n g , t h e y m u s t s t i l l b e c o n s i d e r e d to b e m o d e r a t e σ donors. T h e f a i l u r e of

e l e c t r o n - p a i r donors

to i n t e r a c t w i t h

Rh(TTP)

is

+

reflection of the v e r y great e l e c t r o n d e n s i t y r e s i d i n g o n the R h ( I )

a

atom,

a s t r u c t u r a l p r o p e r t y that is w e l l i l l u s t r a t e d b y t h e c o n t r a s t i n g great r e a c t i v i t y of R h ( T T P )

+

t o w a r d electrophiles.

Reactions of R h ( T T P ) r e a c t i o n of R h ( T T P )

+

+

with Electrophiles. T h e m o s t c h a r a c t e r i s t i c

is its a d d i t i o n to electrophiles.

H , N O , B F , SOo, t e t r a c y a n o e t h y l e n e , a n d 0 +

+

3

characterized products. cules as S 0 , 0 , 2

It combines

with

to f o r m a series of w e l l

T h e variations i n reactivity t o w a r d such mole

and B F

2

2

3

t h a t is o b s e r v e d

among the many k n o w n

s q u a r e - p l a n a r d complexes w e r e a t t r i b u t e d to the f o l l o w i n g factors ( 1 5 ) : 8

( a ) the e l e c t r o n affinity of the c o v a l e n t m o l e c u l e , ( b ) the n u c l e o p h i l i c i t y of the m e t a l i n the c o m p l e x , a n d ( c ) the a b i l i t y of d o r b i t a l s o n the m e t a l to o v e r l a p effectively w i t h s u i t a b l e o r b i t a l s o n t h e e l e c t r o p h i l e . s u c h as 0

2

and S 0

2

Molecules

are most a p p r o p r i a t e l y v i e w e d as π acids of c o n s i d

erable electron affinity, a l t h o u g h t h e y d o h a v e some a b i l i t y to act as σ donors, a n d also as L e w i s ( σ - b o n d i n g ) acids. Solutions of [ R h ( T T P ) ] P F trifluoride

etherate

to

give

6

the

i n a c e t o n i t r i l e react r e a d i l y w i t h b o r o n adduct

[F BRh(TTP)]PF · CH CN 3

6

3

w h i c h was i s o l a t e d as a l i g h t y e l l o w s o l i d . I n a d d i t i o n to the u s u a l b a n d s for [ R h ( T T P ) ] P F , the I R s p e c t r u m of the a d d u c t has b a n d s at 1055 G

( s t r o n g ) , 520 ( m o d e r a t e ) , a n d 520 c m " unit (16).

1

a n d 2290 c m "

T h e b a n d s at 1055

are consistent w i t h the existence of the F B R h s t r u c t u r a l 3

T h e a b s o r p t i o n at 2290 c m " is assignable to V O N for C H C N . 1

S i n c e this b a n d occurs at 2278 c m " frequencies

(weak).

1

a m o n g its complexes,

1

3

i n p u r e a c e t o n i t r i l e a n d at l o w e r

the C H C N 3

is a s s u m e d to b e

unco

o r d i n a t e d . T h e m o l a r c o n d u c t a n c e i n a c e t o n i t r i l e of [ F B R h ( T T P ) ] P F 3


6

370

INORGANIC

COMPOUNDS WITH

UNUSUAL PROPERTIES

is 132 c m / o h m m o l e w h i c h i n d i c a t e s that the substance is a u n i - u n i v a l e n t 2

e l e c t r o l y t e (11).

T h u s the a d d u c t is assigned a

five-coordinate

structure,

a n d i t p r o b a b b l y exists as a d i s t o r t e d t e t r a g o n a l p y r a m i d w i t h t h e s u l f u r atoms of the T T P f o r m i n g the base a n d t h e B F

3

g r o u p the apex.

T h e f o r m a t i o n of the stable a d d u c t w i t h the L e w i s a c i d B F l i s h e d the e n h a n c e d b a s i c i t y of the R h ( I ) previously

known

Rh(I)-phosphine

in R h ( T T P )

complexes.

Although

( C O ) C l ] a d d s B F , t h e r h o d i u m a n a l o g does not (17). 3

3

or B C 1 , is r e q u i r e d for a n o b s e r v a b l e i n t e r a c t i o n w i t h 3

[Rh(PPh )(CO)Cl]

Indeed,

(18).

3


[Ir(PPh )-

A stronger L e w i s

3

a c i d , e.g. B B r

estab

3

o v e r t h a t of t h e

+

k n o w n to f o r m a stable B F propyl)phenylphosphine

3

the

only

other

Rh(I)

complex

a d d u c t is c h l o r o - b i s ( 3 - d i p h e n y l p h o s p h i n o -

rhodium(I)

of the r h o d i u m i n [ R h ( T T P ) ]

T h e enhanced nucleophilicity

(19).

is c o n s i d e r e d

+

as e v i d e n c e of the p o o r

7r-acceptor q u a l i t i e s of the s u l f u r atoms i n the thioether l i g a n d as c o m p a r e d w i t h those of the p h o s p h o r u s atoms i n t h e i r s i m i l a r c o m p l e x e s . The bright yellow bubbling S 0

2

complex

[Rh(TTP)S0 ]C10

isolated

by

in methanol, followed

by

2

t h r o u g h a s o l u t i o n of R h ( T T P )

+

was

4

the a d d i t i o n of L i C 1 0 . Its m o l a r c o n d u c t a n c e ( C H N 0 ) is 90 4

3

cm /ohm 2

2

m o l e w h i c h i n d i c a t e s t h a t t h e salt is a u n i - u n i v a l e n t electrolyte.

The

s y m m e t r i c a n d a n t i s y m m e t r i c v i b r a t i o n a l frequencies

for the S - b o n d e d

l i g a n d i n this c o m p l e x o c c u r at v

1165 c m " .

agree w e l l w i t h those (19, 20, 21).

8 y m

, 1032 c m "

observed for

other

m i n e d b y L a P l a c a a n d Ibers

(22).

v sym a

2

These

1

S-bonded

T h e L e w i s a c i d c h a r a c t e r of S 0

is e v i d e n t i n the x - r a y s t r u c t u r e of

and

1

S0

complexes

2

i n its a d d u c t s of this class

[IrCl ( S 0 ) ( C O ) ( PPh ) ]

as deter

It reveals that the S 0

l i g a n d is

2

3

2

2

b o n d e d to the m e t a l via the s u l f u r a t o m .

T h e m e t a l is c o o r d i n a t e d i n a

t e t r a g o n a l p y r a m i d a l f a s h i o n w i t h the S 0

2

a b o u t the s u l f u r a t o m of the S 0

2

at the apex.

The

geometry

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

the d o n a t i o n b y the m e t a l of a p a i r of electrons to a n a p p r o x i m a t e l y

sp

s

h y b r i d i z e d vacant sulfur orbital. Tetracyanoethylene s u r p r i s i n g t h a t the Rh(TTP)

+

3

2

TCNE

to

an acetonitrile

solution

leads to t h e v e r y r a p i d f o r m a t i o n of the o r a n g e - y e l l o w

[( T C N E ) R h ( T T P ) ] \ CH N0

( T C N E ) is a v e r y strong π a c i d so i t is not

a d d i t i o n of

is 93 c m / o h m 2

The

molar

mole

conductance

s p e c t r u m has a s h a r p b a n d at 2210 c m " that is a t t r i b u t a b l e to the C = N b a n d i n the I R s p e c t r u m of

of

its

P F " salt 6

(uni-univalent electrolyte), 1

cm"

1

T h e r e is a s i m i l a r

[(TCNE)Ir(PPh ) (CO)Cl] 3

in

a n d its I R

w i t h a s h o u l d e r at 2195

g r o u p s of T C N E .

of

adduct

(23,

2

24).

It

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

Rh(I).

T h e light green nitrosyl complex [ R h ( T T P ) N O ] ( B F ) 4

p r e p a r e d b y a d d i n g a n a c e t o n i t r i l e s o l u t i o n of N O B F

4

to

2

is r e a d i l y

[Rh(TTP)]BF

d i s s o l v e d i n a c e t o n i t r i l e . T h e m o l a r c o n d u c t a n c e of this c o m p o u n d


4

(245

29.

LEMKE

ET

Macrocyclic

AL.

Tetradentate

371

Thioethers

c m / o h m m o l e i n C H C N ) confirms t h a t i t is a d i - u n i v a l e n t electrolyte. 2

3

Its I R s p e c t r u m has a n N O s t r e t c h i n g m o d e at 1750 c m " w h i c h is c o m 1

p a r a b l e to that of other r e l a t e d n i t r o s y l complexes—e.g. v o =

1680 c m "

N

for

[IrCl(CO)(PPh ) (NO)] 3

2

[(CH ) PPh ] }Cl]BF 2

(26).

3

3

2

(19),

4

(25),

+

1699

cm"

a n d 1560 c m "

for

1

for

1

[IrCl (NO)(PPh ) ] 2

3

T h e s e three c o m p o u n d s a l l h a v e bent M - N - O g r o u p i n g s (26,

T h e compounds F e ( C O ) ( N O ) 2

(VNO =

(v

2

N 0

donates a n e l e c t r o n p a i r to N O

+

2

27).

— 1 8 1 0 , 1766) a n d M n ( C O ) ( N O )

1823, 1734) h a v e l i n e a r M - N - O g r o u p i n g s (28).

that [ R h ( T P P ) ]

1

[Rh(NO){PhP-

+

3

I t is suggested

a n d forms a c o m p l e x


i n w h i c h the b e n t N O g r o u p o c c u p i e s t h e a x i a l m e t a l i o n site. T h e L e w i s base b e h a v i o r of R h ( I ) complex might combine

in R h ( T T P )

suggests that the

w i t h the p r o t o n ; this was d e m o n s t r a t e d .

a d d i t i o n of a 4 8 % aqueous s o l u t i o n of H B F to a s o l u t i o n of

+

[Rh(TTP)]BF

coordinate adduct [ H R h ( T T P ) ]

4

2 +

4

The

from a freshly opened bottle

i n nitromethane produced

the

five-

w h i c h was i s o l a t e d as t h e y e l l o w - g r e e n

tetrafluoroborate salt [ H R h ( T T P ) ] ( B F ) . T h e I R s p e c t r u m of the salt 4

2

has a w e a k b a n d at 2220 c m " w h i c h is assignable to the R h - H s t r e t c h i n g 1

vibration. 2105 c m "

The R h - H mode in [ H R h C l ( P P h ) ] 0 · 5 C H C 1 2

(29),

1

L

T h e molar conductance

(19).

3

3

2

that i n [ H R h { P h P [ ( C H > ) P P h ] } C l ] 3

2

2

2

occurs at

at 2195

2

cm"

of t h e p r o t o n a t e d m a t e r i a l i n C H C N 3

1

is

279 c m / o h m m o l e w h i c h is i n d i c a t i v e of a d i - u n i v a l e n t electrolyte. 2

T h e most w i d e l y s t u d i e d a d d u c t s of s q u a r e - p l a n a r d

8

those w i t h the o x y g e n m o l e c u l e 0

2

c o m p l e x e s are

References 30 a n d 31 for r e v i e w ) .

(see

I n these d e r i v a t i v e s , the t w o o x y g e n atoms are b o u n d e q u i v a l e n t l y to t h e m e t a l a t o m , a n d the b o n d i n g scheme is often c o m p a r e d to t h a t p r o p o s e d for e t h y l e n e a d d u c t s .

P r e s u m a b l y , the 0

2

donates a p a i r of elec-

trons to the b o n d , b u t the m e t a l also donates s t r o n g l y to the b o n d . the m e t a l a t o m c a n b a c k d o n a t e v e r y strongly, i r r e v e r s i b l e 0

When

b i n d i n g is

2

expected. W h e n f r e s h l y r e d u c e d solutions c o n t a i n i n g R h ( T T P ) to a i r , the b r o n z e - g o l d color changes to b r o w n .

+

are e x p o s e d

T h e a d d i t i o n of s o d i u m

t e t r a p h e n y l b o r a t e leads to t h e i s o l a t i o n of a b r o w n d i a m a g n e t i c salt w i t h t h e s t o i c h i o m e t r y [ R h ( T T P ) 0 ] ( B P h ) . C a r e f u l s t u d y of t h e I R s p e c t r a 2

4

of t h e p r o d u c t a n d r e l a t e d m a t e r i a l s leads to the assignment of a b a n d at 845 c m "

1

to the RhOo g r o u p .

is p r o b a b l y not p u r e l y a n O - O

A s others suggested

b i n e d w i t h an M - O stretching motion. adducts, the 0

2

of 0 . 2

[Rh(TTP)0 ] 2

(32, 3 3 ) , the b a n d

s t r e t c h i n g m o d e , b u t r a t h e r i t is

c a n be r e d u c e d b a c k to R h ( T T P ) ;

+

+

0

2

however,

is not r e m o v e d m e r e l y b y h e a t i n g or l o w e r i n g t h e p a r t i a l p r e s s u r e ( I n the course of studies of R h ( I I )

complexes formed w i t h the

l i g a n d s of interest here, w e d i s c o v e r e d that R h ( T T P ) n

intermediate i n the 0 Rh (TTP) n

com-

A s is t r u e of m a n y of t h e

+

forms

2

o x i d a t i o n of R h ( T T P ) .

a 1:1

+

0

2

adduct

+

is f o r m e d as a n

Still more remarkably,

t h a t is closely

analogous


to

the

372

INORGANIC

cobalt (II) adducts w i t h 0 . 2

COMPOUNDS WITH

UNUSUAL

PROPERTIES

T h e s e matters are the subject of a separate

publication. ) O x i d a t i v e A d d i t i o n Reactions

of R h ( T T P ) \

T h i s m a t e r i a l is so

o r g a n i z e d that the t e r m o x i d a t i v e a d d i t i o n m a y be u s e d i n a

somewhat

r e s t r i c t e d sense. I n a s m u c h as b o t h n u c l e o p h i l i c a n d e l e c t r o p h i l i c a d d i t i o n w e r e a l r e a d y c o n s i d e r e d , the reactions that w e r e r e s e r v e d for this section on oxidative addition involve a simultaneous real change i n coordination n u m b e r f r o m f o u r to six a n d a f o r m a l c h a n g e i n t h e o x i d a t i o n state of R h f r o m I to I I I .


Rh(TTP)

reacts w i t h a l k y l h a l i d e s , a c y l h a l i d e s , a r o y l h a l i d e s , a n d

+

s u l f o n y l h a l i d e s , b u t it shows n o e v i d e n c e hydrogen.

of r e a c t i o n w i t h

molecular

T h e s e observations f u r t h e r e m p h a s i z e the fact that R h ( T T P )

is essentially a n u c l e o p h i l e a n d it therefore reacts w i t h those R X that c a n o x i d a t i v e l y a d d b y n u c l e o p h i l i c a t t a c k ( 3 4 ) . does not react w i t h H , a n d H 2

2

a concerted mechanism (35).

+

reagents

Rh(TTP)

+

seems a l w a y s to a d d to d? c o m p l e x e s via It appears that R h ( T T P )

has v e r y l i t t l e

+

d i r a d i c a l c h a r a c t e r , i.e. it is not a g o o d a n a l o g of a c a r b e n e ( 3 5 ) .

It is

possible that this u n r e a c t i v i t y m a y b e associated w i t h the stereochemistry of c h e l a t i o n b y t h e m a c r o c y c l i c l i g a n d . E a r l i e r studies o n the o x i d a t i v e a d d i t i o n reactions of R h ( I ) c o m p l e x w i t h a tetraaza m a c r o c y c l e r e v e a l e d t h a t the R h ( I ) molecular H

2

h a d s t r o n g n u c l e o p h i l i c p r o p e r t i e s b u t the a c t i v a t i o n of

was not r e p o r t e d (36, 37).

T h i s p o s s i b i l i t y is s u p p o r t e d b y

reports that d i a l k y l sulfide c o m p l e x e s of r h o d i u m c h l o r i d e c a t a l y z e the hydrogénation of olefins

(38).

I n some w a y s , the simplest a n d least i n t e r e s t i n g o x i d a t i v e a d d i t i o n reactions are those w i t h halogens. H o w e v e r , t h e r e w a s a r a t h e r i n t e r e s t i n g a n d useful was

finding

i n t h e r e a c t i o n of R h ( T T P )

fran5-Rh(TTP)Cl . 2

+

E a r l i e r studies

(4),

with C l — t h e product

+

2

in which

the

Rh(III)

c o m p l e x e s of T T P w e r e p r e p a r e d b y s u b s t i t u t i o n reactions, y i e l d e d o n l y m-Rh(TTP)Cl

2

+

.

T h u s , as t h e result of t w o v e r y different p r e p a r a t i v e

routes, the cis a n d trans isomers are b o t h a v a i l a b l e . T h e N M R s p e c t r a are s e c o n d o r d e r a n d difficult to o b t a i n b e c a u s e of s o l u b i l i t y p r o b l e m s . T h e y are sufficiently w e l l r e s o l v e d to s h o w that t h e isomers are different ( F i g u r e 1 ) . T h e f a r - I R a n d e l e c t r o n i c s p e c t r a of the c o m p o u n d s p r o v i d e s u p p o r t for the i s o m e r i c s t r u c t u r a l assignments. T h e f a r - I R s p e c t r u m of d s - [ R h ( T T P ) C l ] P F 2

strong bands

at 307 a n d 290 c m "

stretching vibrations predicted

1

6

has t w o

moderately

that are assignable to the

for a c i s - d i a c i d o - M L X 4

2

complex

Rh-Cl (4).

T h e f a r - I R s p e c t r u m of the p r o d u c t o b t a i n e d b y o x i d a t i v e a d d i t i o n of c h l o r i n e to R h ( T T P )

+

has a single strong b a n d at 360 c m " that is a s s i g n 1

a b l e to a n R h - C l s t r e t c h i n g v i b r a t i o n . S i m i l a r l y , a single b a n d at 362 c m " w a s assigned to the lone R h - C l s t r e t c h , a n d W a l t o n ( I ) 1

considered

this e v i d e n c e of t h e trans s t r u c t u r e of [ R h ( D T H ) C l ] C l . 2

2


29.

LEMKE

Macrocyclic

E T AL.

Tetradentate

ι

Thioethers

373


DMSO

ι

1—J

1

5.0 Figure Cl ]PF 2

6

—J—

I

I

7Ό

j

8Ό

1

1

6.0

I

1

1

70

I

I

J

9Î0

I

I

8.0

Î0.0

I

I

I

9.0

10.0

1. Proton NMR spectra of cis-[Rh(TTP)(top) and of trans-[Rh(TTP)Cl }PF (bottorn) 2

G

A s w a s m e n t i o n e d i n t h e r e p o r t o n m - [ R h ( T T P ) C l ] C l (4), t h e 2

e l e c t r o n i c spectra o f J r a r w - M L X 4

2

isomers e x h i b i t transitions a t l o w e r

energies a n d lesser intensities t h a n d o those o f the cis isomers because of a greater d i s t o r t i o n i n t h e l i g a n d field o f t h e cis isomers. s p e c t r a of cis- a n d i r a r w - [ R h ( T T P ) C l ] P F 2

6

T h e visible

a r e p r e s e n t e d i n F i g u r e 2.

T h u s , the e l e c t r o n i c s p e c t r u m of f r a n s - [ R h ( T T P ) C l ] P F 2

e

has absorptions

at 426 ( = 291), 340 ( s h , c = 582), a n d 260 n m ( = 36,683) w h e r e a s c

€

trans- [ R h ( c y c l a m ) C 1 ] 2

+

( c y c l a m = 1,4,8,11-tetraazacyclotetradecane)

has absorptions at 406 (c = 78), 310 ( s h , € — 80), 242 ( s h , = 3300), c

a n d 204 n m ( = 37,100) (39). W i t h t h e s y m m e t r y a p p r o x i m a t e d as D , éh

€

the first t w o b a n d s c a n b e a s s i g n e d to t h e d-d transitions E l

*A

x 2

g

Inorganic Compounds with Unusual Properties - ACS Publications

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