Actinide Chemistry

2 Donor Properties of Pyrophosphate Derivatives

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Complexes of Rare Earth Ions with Octamethylpyrophosphoramide 1

MELVIN D. JOESTEN and ROBERT A. JACOB Southern Illinois University, Carbondale, Ill. Complexes of rare earth ions with octamethylpyrophosphoramide (OMPA) have been prepared and characterized. The stoichiometry of the complexes is either Ln(ClO ) · 3 OMPA · x H O where Ln is La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Y, and x is 1-4 or Ln(ClO ) · 4 OMPA · x H O where Ln is La, Eu, and Ho, and x is 0,1,4. The infrared spectra of both types of complexes are interpreted on the basis of a coordination number of eight or more for the lanthanide ions. 4 3

2

4 3

2

T J r e v i o u s w o r k i n this l a b o r a t o r y (5, 6, 14) s a t i l i t y of o c t a m e t h y l p y r o p h o s p h o r a m i d e

has d e m o n s t r a t e d t h e v e r ( O M P A ) as a l i g a n d . S t a b l e

complexes of O M P A Ο

!p

(C H ) N 3

2

Ο Ο

N(CH ) 3

Ρ 2

Ν (C H ) 3

N(CH ) 3

2

2

Octamethylpyrophosphoramide w i t h a l k a l i , a l k a l i n e e a r t h , a n d t r a n s i t i o n m e t a l ions h a v e b e e n i s o l a t e d . T h e s t a b i l i t y of c o m p l e x e s of rare e a r t h ions is often c o m p a r e d w i t h that of the a l k a l i n e e a r t h ions (11). • 3 O M P A and C a ( C 1 0 ) 4

2

S i n c e complexes s u c h as M g ( 0 1 0 ^ 2

' 3 O M P A are q u i t e stable (14),

we decided

to e x t e n d o u r studies to the reactions of O M P A w i t h rare e a r t h ions. 1

Present address: D e p a r t m e n t of C h e m i s t r y , V a n d e r b i l t U n i v e r s i t y , N a s h v i l l e , T e n n .

13 Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.

14

LANTHANIDE/ACTINIDE

CHEMISTRY

Experimental Reagents. T h e O M P A u s e d w a s 9 1 % p u r e ( P e n n s a l t C h e m i c a l s ) . T h i s c o m p o u n d is e x t r e m e l y toxic a n d m u s t b e h a n d l e d w i t h care. O M P A w a s p u r i f i e d b y v a c u u m d i s t i l l a t i o n (6). T h e h y d r a t e d rare e a r t h c h l o rides u s e d w e r e 9 9 . 9 % p u r e ( L i n d s a y D i v i s i o n of A m e r i c a n P o t a s h a n d C h e m i c a l C o r p . ). Preparation of Complexes. Ln(ClO ) · 3 OMPA · χ H 0. The hy d r a t e d m e t a l c h l o r i d e ( 0.0015 moles ) w a s d i s s o l v e d i n 8 m l . of m e t h a n o l . A s t o i c h i o m e t r i c a m o u n t of A g C 1 0 · H 0 was a d d e d to p r e c i p i t a t e A g C l . T h e filtrate w a s d e h y d r a t e d w i t h 2 m l . of 2 , 2 - d i m e t h o x y p r o p a n e (16) for 45 m i n . , a n d 0.0077 moles of O M P A w a s a d d e d . Excess ether 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 . T h e c o m p o u n d s w e r e d r i e d u n d e r v a c u u m at r o o m t e m p e r a t u r e . T h e complexes w h e r e L n is L a , C e , S m , E u , D y were recrystallized from a methanol-ether solution. Ln(ClO ) - 4 OMPA · χ H 0. T h e c o m p o u n d s w h e r e L n is L a a n d E u w e r e p r e p a r e d as o u t l i n e d a b o v e except that a l a r g e excess of O M P A w a s a d d e d (0.012 m o l e s ) . T h e c o m p l e x of E u ( I I I ) w a s r e c r y s t a l l i z e d f r o m a m e t h a n o l - e t h e r s o l u t i o n . H o w e v e r , attempts to r e c r y s t a l l i z e L a ( C 1 0 ) s * 4 O M P A r e s u l t e d i n the f o r m a t i o n of L a ( C 1 0 ) · 3 O M P A • 2H 0. T h e H o (III) complex, H o ( C 1 0 ) · 4 O M P A · 4 H 0 , was prepared i n m u c h the same w a y except that the s o l u t i o n w a s c o o l e d to 0 ° C . after a d d i n g a n excess of O M P A (0.012 m o l e s ) . A t this t e m p e r a t u r e , crystals of the c o m p l e x separated f r o m s o l u t i o n . T h e c o m p l e x w a s filtered off, recrystallized from a methanol-ether solution, a n d d r i e d under v a c u u m at r o o m t e m p e r a t u r e . I{ 3


4

h s

2

2

2

4

4

3

2

4

2

ΙΛ

L3

3

2

1.1

WAVENUMBERS

Figure 1. I

Infrared

Spectra of MgtOMPA^ClO^, LafClOJs · 3 OMPA ·

1.0 CM"

0.9 xlO"

1

0.8

0.7

3

La(ClO ) 2H 0

i 3

· 4 OMPA,

2

Mg(OMPA) (ClOJ 3

II LctfClOJs

2

· 4 OMPA

III La(ClO )

h s

· 3 OMPA

·

2H 0

Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.

2

and


2.

JOESTEN AND JACOB

Pyrophosphate

15

Derivatives

LaCls ' 2 OMPA · Η,Ο. H y d r a t e d l a n t h a n u m c h l o r i d e (0.0031 m o l e ) w a s d i s s o l v e d i n a m i x t u r e of 2 m l . of 2 , 2 - d i m e t h o x y p r o p a n e a n d 4 m l . of m e t h a n o l . T h e s o l u t i o n w a s s t i r r e d for 1| h o u r s at r o o m t e m p e r a t u r e , a n d 0.0124 moles of O M P A w a s a d d e d . W h e n ether w a s a d d e d , a n o i l s e p a r a t e d f r o m s o l u t i o n , w h i c h w a s extracted several times u n t i l a w h i t e precipitate formed. O i l s o b t a i n e d b y r e a c t i o n of other r a r e e a r t h c h l o r i d e s w i t h O M P A b y the a b o v e p r o c e d u r e w e r e i n t r a c t a b l e . Spectral Measurements. I n f r a r e d s p e c t r a of N u j o l m u l l s of the c o m plexes w e r e o b t a i n e d w i t h a B e c k m a n I R 5 - A spectrophotometer. Ultra v i o l e t a n d v i s i b l e spectra w e r e r e c o r d e d o n a B e c k m a n D K - 1 A spec trophotometer. A V a r i a n A - 5 6 / 6 0 N M R spectrometer w a s u s e d to m e a s u r e the p r o t o n signals of solutions of O M P A , M g ( C 1 0 ) 2 * 3 O M P A , La(C10 ) · 4 OMPA, La(C10 ) · 3 OMPA 2 H 0 , and Y ( C 1 0 ) · 3 O M P A · 2 H 0 i n m e t h y l e n e c h l o r i d e . T h e N M R measurements w e r e m a d e at 3 5 ° C . w i t h t e t r a m e t h y l s i l a n e as reference. Conductance Measurements. A c o n d u c t a n c e b r i d g e ( I n d u s t r i a l I n struments, Inc. ) w a s u s e d to measure m o l a r c o n d u c t i v i t i e s of 1 Χ ΙΟ" M solutions of the complexes i n n i t r o m e t h a n e . Analyses. C a r b o n , h y d r o g e n , a n d n i t r o g e n analyses w e r e p e r f o r m e d by Alfred Bernhardt, Max-Planck-Institute, Mulheim, Germany. 4

4

3

4

3

2

4

3

2

3

Results and Discussion E l e m e n t a l analyses for the rare e a r t h complexes

of O M P A are r e

p o r t e d i n T a b l e I. T h e complexes are of t w o t y p e s : ( 1 ) L n ( C 1 0 ) · 3 O M P A · χ H 0 w h e r e L n is L a , C e , P r , N d , S m , E u , G d , T b , D y , H o , E r , Y , a n d χ is 1-4. 4

(2)

3

Ln(C10 ) 4

2

· 4 O M P A - χ H 0 w h e r e L n is L a , E u , H o , a n d χ is

3

2

0,1,4 T h e m o l a r c o n d u c t i v i t y values for n i t r o m e t h a n e solutions of complexes

( T a b l e I ) are i n t h e r a n g e e x p e c t e d

(200-250).

f o r 3:1

(14)

T h e m o l a r c o n d u c t i v i t y v a l u e for L a C l

· 2 OMPA

3

the

electrolytes · H 0 2

i n d i c a t e s that it is a 1:1 electrolyte i n n i t r o m e t h a n e . T h e c o n d u c t i v i t i e s of m e t h y l e n e c h l o r i d e solutions of O M P A complexes of S m ( I I I ) , T b ( I I I ) , D y ( I I I ) , a n d E r ( I I I ) w e r e also m e a s u r e d .

A l l of these complexes

have

i o n i c species present i n m e t h y l e n e c h l o r i d e ( T a b l e I, footnote c ) . Variations in Infrared Spectra. T a b l e I I s u m m a r i z e s the positions of the i n f r a r e d b a n d s of P = 0 , Ρ — Ο — Ρ , Ρ — N , a n d C 1 0 " . T h e features 4

of the i n f r a r e d b a n d s of L n ( C 1 0 ) 4

3

· 3 O M P A · χ H 0 and L n ( C 1 0 ) 2

4

3

· 4

O M P A · χ H 0 are different f r o m those o b s e r v e d for the a l k a l i n e e a r t h 2

complexes, b u t the i n f r a r e d s p e c t r u m of L a ( C 1 0 ) 4

to t h a t of M g ( C 1 0 ) 4

3

· 3 OMPA.

3

· 4 O M P A is s i m i l a r

F i g u r e 1 illustrates the s i m i l a r i t y i n the

B = 0 , Ρ — Ο — P , C K V , a n d Ρ — Ν b a n d s for M g ( C 1 0 ) 4

La(C10 )

3

La(C10 )

3

4

4

· 4 OMPA.

2

· 3 O M P A and

T h e differences that a p p e a r i n the s p e c t r u m of

· 3 O M P A · 2 H 0 ( F i g u r e 1) are e v e n m o r e a p p a r e n t i n c o m 2

plexes of O M P A w i t h h e a v i e r l a n t h a n i d e s ( F i g u r e 2 ) .

T h e m a i n differ-


LANTHANIDE/ACTINIDE

16

Table I.

Analytical and Conductivity Data %

23.0 21.6 24.3 21.6 21.9 21.9 21.4 21.4 23.8 21.3 21.0 20.7 20.7 22.9 21.2 22.5

23.2 21.5 24.1 21.6 22.3 22.2 21.2 21.2 23.9 21.3 21.3 20.7 20.5 22.7 21.3 22.3

3

4

3

4

3

4


Found

2

4

3

4

3

4

3

4

3

4

3

δ

2

2

2

s

2

3

2

4

3

4

3

2

4

3

2

4

a

2

4

4

4

2

3

2

3

2

3

Carbon

Calcd, LaCl · 2 OMPA · H 0* L a ( C 1 0 ) · 3 O M P A · 2H„0 La(C10 ) · 4 OMPA Ce(C10 ) · 3 OMPA · 2 H 0 Pr(C10 ) · 3 OMPA · H 0 Nd(C10 ) · 3 OMPA · H 0 Sm(C10 ) · 3 OMPA · 2 H 0 Eu(C10 ) · 3 OMPA · 2H 0 Eu(C10 ) · 4 OMPA · H O Gd(C10 ) · 3 OMPA · 2H 0 Tb(C10 ) · 3 OMPA · 3H 0 Dy(C10 ) · 3 OMPA · 4H 0 Ho(C10 ) · 3 OMPA · 4 H 0 Ho(C10 ) · 4 OMPA · 4 H 0 Er(C10 ) · 3 OMPA · 2H 0 Y(C10 ) · 3 OMPA · 2H 0 3

CHEMISTRY

2

% C I ; C a l c d . , 12.8; F o u n d , 12.6. 1 Χ Κ Τ M nitromethane solutions at 2 5 ° C . 3

ences i n c l u d e a s h o u l d e r at 9 3 0 - 9 4 0 c m . " o n t h e m a i n Ρ — Ο — Ρ b a n d t h a t 1

b e c o m e s a separate p e a k f o r t h e h e a v i e r l a n t h a n i d e s ; a s h o u l d e r at 1 0 3 0 1 0 3 5 c m . " o n the Ρ — N i b a n d for the lighter lanthanide complexes; the 1

s p l i t t i n g of t h e Ρ — N

2

b a n d i n a l l 3 : 1 complexes;

t h e a p p e a r a n c e of

shoulders at 1 1 2 0 - 1 1 3 0 c m . " a n d 1 0 7 0 c m . " o n t h e p e r c h l o r a t e b a n d ; 1

and

1

t h e presence of w a t e r b a n d s at 3 3 5 0 a n d 1 6 2 5 c m . " ( 1 0 ) . 1

T h e differences i n t h e i n f r a r e d spectra m a y b e c a u s e d b y : (1)

COORDINATED PERCHLORATE.

T h e s h o u l d e r s at 1 1 2 3 , 1 0 3 5 , a n d

9 3 0 - 9 4 0 c m . " w h i c h a p p e a r i n t h e i n f r a r e d s p e c t r a of several of t h e l a n t h a n i d e c o m p l e x e s of O M P A c o u l d b e c a u s e d b y c o o r d i n a t e d p e r 1

chlorate ( 4 , 1 3 ,

17).

T h e i n f r a r e d s p e c t r a of T b ( C 1 0 ) 4

3

· 3 O M P A

· 3 H

2

0 and E r ( C 1 0 ) 4

3

• 3 O M P A · 2 H 0 i n m e t h y l e n e c h l o r i d e are of interest since t h e s p l i t t i n g of t h e Ρ — Ο — Ρ b a n d is s t i l l o b s e r v e d e v e n t h o u g h t h e p e r c h l o r a t e b a n d is that e x p e c t e d f o r i o n i c p e r c h l o r a t e . S i n c e t h e p e r c h l o r a t e b a n d s i n these c o m p l e x e s are n o t as s h a r p or as w e l l r e s o l v e d as those o b s e r v e d p r e v i o u s l y f o r c o o r d i n a t e d p e r c h l o r a t e (4, 13, 17), t h e presence of c o o r d i n a t e d p e r c h l o r a t e is u n l i k e l y . ( 2 ) H Y D R O G E N B O N D I N G . Some of t h e w a t e r m o l e c u l e s c o u l d b e c o o r d i n a t e d to t h e m e t a l i o n , a n d some c o u l d b e h y d r o g e n b o n d i n g w i t h O M P A , C 1 0 " , or other w a t e r molecules. [ W e w o u l d l i k e to t h a n k one of the referees f o r this suggestion.] T h e r e p o r t e d s t r u c t u r e of Y ( a c a c ) · 3 H 0 , w h e r e acac represents acetylacetonate, has t w o w a t e r m o l e c u l e s a t t a c h e d to y t t r i u m a n d o n e w a t e r m o l e c u l e w h i c h acts as a b r i d g e b y h y d r o g e n b o n d i n g w i t h w a t e r m o l e c u l e s c o o r d i n a t e d to t w o different y t t r i u m ions ( 3 ) . I n t h e O M P A 2

4

3

2


2.

JOESTEN A N D JACOB

for O M P A %

Pyrophosphate

17

Derivatives

Complexes of Rare Earth Ions %

Hydrogen

Nitrogen

A

b

M

Cm. ohm mole' 2

Found


Calcd.

Found

Calcd.

6.03

6.12

13.4

13.3

60

5.75

5.52

12.6 14.2

12.6

206 289

6.17

6.15

5.75

5.60 5.72

12.6

13.5 12.4

12.8

12.7

5.66 5.60

12.6 12.5 12.3

5.66 5.66 5.70 5.68 6.12

5.65 6.23

12.8 12.5 12.5 13.9

5.67

5.58

12.4

5.74 5.79

5.97 5.50

12.3 12.1

5.78 6.24

5.72 6.10 5.63

12.1 13.3 12.3

5.86

13.1

5.63 5.97

1

1

218 227 230 228 234

13.6 12.3

C

—

250

12.3

258 264

11.9 12.0 13.0

266

12.2 13.0

268 257

C

C

— C

Am i n C H C 1 is 5 0 , 4 6 , 4 3 , 41 for O M P A complexes of S m ( I I I ) , T b ( I I I ) , D y ( I I I ) , a n d E r ( I I I ) , respectively. C

2

2

1.5

1.3

1.1

ω

0.9

WAVENUMBERS, CM* χ I 0 " 1

Figure 2.

Infrared Spectra of NdfClOJ, · 3 OMPA · H 0, Th(ClO ) OMPA · 3H 0, and Hor ' \ ) · 3 OMPA · 4H 0 2

{

J

2

IV NdfClOJs

· 3 OMPA

· H0

Th(ClO )

· 3 OMPA

·

3H 0

VI Ho(ClO )

* 3 OMPA

·

4H 0

V

3

h s

It s

3

u s

2

2

2

2


· 3

18

LANTHANIDE/ACTINIDE

CHEMISTRY

Table II.

Infrared

Compound

P=0 cm:

OMPA L a C L · 2 O M P A · H..O La(C10 ) • 4 OMPA La(C10 ) • 3 OMPA 2H 0 C e ( C 1 0 ) • 3 O M P A • 2HoO Pr(C10 ) · 3 OMPA · H 0 Nd(C10 ) • 3 OMPA • H 0 Sm(C10 ) • 3 OMPA • 2 H 0 Eu(C10 ) • 3 OMPA • 2H 0 Eu(C10 ) • 3 OMPA • x H O Eu(C10 ) • 4 OMPA • H 0 Gd(C10 ) • 3 OMPA • 2H 0 T b ( C 1 0 ) • 3 O M P A • 3H>0 Tb(C10 ) • 3 OMPA • x H O Tb(C10 ), • 3 OMPA • 3 H , 0 inCH C1 Dy(C10 ) • 3 OMPA •4H 0 Ho(C10 ) • 3 OMPA •4H 0 H o ( C 1 0 ) , • 4 O M P A • 4H.,0 Er(C10 ) • 3 OMPA 2H 0 E r ( C 1 0 ) • 3 O M P A • 2KUO i n C H C 1 Y ( C 1 0 ) · 3 O M P A · 2Ho6 Y(C10 ) · 3 OMPA · x H O

1237 1198 1197 1195 1193 1197 1196 1195 1194 1195 1177 1197 1197 1194 1188 1191 1197 1176 1192 1185 1198 1195

V

V

4

3

4

3

4

3


4

2

3

2

4

3

4

3

4

3

4

3

4

3

4

2

2

2

3

4

3

4

3

f

2

2

2

c

2

4

2

4

3

2

4

s

2

2

4

4

3

4

3

4

3

4

3

2

2

2

&

2

c

P—Ο—Ρ cm: 1

1

914 908 927 909 (903) 911 (924) 912 (935) 911 (940) 908 (940) 909 (945) 912 (930) 917 911,943 911, 945 915, 935 935 (895) 910 (940) 908 (942) 908 900 (940) 934 (892) 903, 940 903

N u m b e r s i n parentheses are shoulders on m a i n peaks. A l l complexes w i t h water molecules i n f o r m u l a have water bands at 3350 a n d 1625 cm. .

a

b

- 1

complexes of l a n t h a n i d e ions the s p l i t t i n g of the Ρ — Ο — Ρ a n d Ρ — Ν b a n d s w o u l d be e x p e c t e d if w a t e r m o l e c u l e s are h y d r o g e n b o n d i n g to the o x y g e n or n i t r o g e n sites. T h e i n f r a r e d spectra of the O M P A complexes of Y ( I I I ) , E u ( I I I ) , a n d T b ( I I I ) w e r e o b t a i n e d b o t h before a n d after the complexes h a d b e e n h e a t e d at 1 0 0 ° C . u n d e r v a c u u m for several hours. A f t e r the heat treatment, the w a t e r b a n d s w e r e less intense, the Ρ — Ο — Ρ b a n d w a s s m o o t h e d out i n the Y ( I I I ) c o m p l e x , a n d the Ρ — Ν b a n d s w e r e u n c h a n g e d . S i n c e the w a t e r b a n d s d i d not d i s a p p e a r after the heat treat m e n t , at least p a r t of the w a t e r m o l e c u l e s are t i g h t l y h e l d . ( 3 ) INTERACTION O F T H E M E T A L I O N W I T H Ρ—Ο—Ρ O X Y G E N S OR

Ρ—Ν

N I T R O G E N S . S i n c e the differences i n i n f r a r e d spectra are o b s e r v e d for b o t h L n ( C 1 0 ) * 4 O M P A · χ H 0 a n d L n ( C 1 0 ) ' 3 O M P A • χ H 0 b u t not for L a ( C 1 0 ) ' 4 O M P A , the effect of the w a t e r m o l e c u l e s is p r o b a b l y m o r e i m p o r t a n t t h a n the s e c o n d a r y b o n d i n g of m e t a l ions w i t h Ρ — Ο — Ρ oxygens or Ρ — Ν nitrogens. R e c e n t l y , rare e a r t h complexes of β-diketone d e r i v a t i v e s h a v e b e e n 4

3

2

4

4

3

2

3

i s o l a t e d i n w h i c h the l a n t h a n i d e s are o c t a c o o r d i n a t e ( 1 , 3, 9 ) .

W e pro

pose t h a t the c o o r d i n a t i o n n u m b e r of the l a n t h a n i d e ions i n the O M P A complexes is at least eight. T h e fact t h a t the P = 0

stretching frequency


2.

JOESTEN A N D JACOB

Pyrophosphate

19

Derivatives

Spectral Data *P-N cm.'

2

cm.'

1

792, 7 6 0 ( 7 7 0 )

— —

1000

765

1097

1000

769,

787

756

988 1003


cm.'

1

1

(980) (1015)

(773)

A

1089

(1123)

1000

(1035)

771,

792

1093

(1070)

1010

(1035)

771,

792

1099

(1075)

(1097)

1010

(1035)

770,

792

1097

(1072)

(1123)

1002

(1035)

770,

792

1092

(1075)

1010

772,

793

1101

(1075)

1010

772,

792

1095

1010

750, 7 7 1 , 7 9 0

1088

1010

771, 793 ( 7 6 5 )

1097

(1065)

1012

772, 7 9 9 ( 7 6 0 )

1097

(1122)

1010

774, 7 9 5 ( 7 6 0 )

1097

(1070)

d

1098

(1070)

1017

771, 792 ( 7 6 0 )

1088

(1065)

1012

771, 795 ( 7 6 0 )

1093

(1075)

1002

748, 771, 7 9 3

1087

1008

771, 794 ( 7 5 7 )

1090

1000

d

1010

(1123)

(1070)

(1065)

(1120)

1096

1003

772, 7 9 3 ( 7 6 0 )

1090

(1123)

(1070)

1005

774, 794 ( 7 6 0 )

1095

(1123)

(1070)

c d

S p e c t r u m taken after complex was heated at 1 0 0 ° C . u n d e r v a c u u m for several hours. Solvent absorption.

of O M P A is s h i f t e d t o l o w e r w a v e n u m b e r s u p o n c o o r d i n a t i o n t o t h e l a n t h a n i d e ions is s u p p o r t f o r c o o r d i n a t i o n o f the m e t a l i o n t o t h e p h o s p h o r y l oxygens. L a n t h a n u m ( I I I ) i n L a ( C 1 0 ) 3 4

" 4 O M P A is p r o b a b l y

o c t a c o o r d i n a t e w i t h O M P A a c t i n g as a b i d e n t a t e l i g a n d . 3

+

X=N(CH ) S

T h e m e t a l ions i n t h e c o m p o u n d s E u ( C 1 0 ) 3 · 4 O M P A · H 0 a n d H o ( C 1 0 ) · 4 O M P A · 4 H 0 m a y be coordinating to water molecules i n a d d i t i o n t o c o o r d i n a t i n g t o f o u r O M P A m o l e c u l e s . H o w e v e r , i t is m o r e l i k e l y that the w a t e r m o l e c u l e s are h y d r o g e n b o n d i n g w i t h t h e l i g a n d . 4

4

3

2


2

20

LANTHANIDE/ACTINIDE

I n t h e complexes w i t h t h e s t o i c h i o m e t r y L n ( C 1 0 ) 4

CHEMISTRY

*3 OMPA

3

*χ

H 0 t h e first six c o o r d i n a t i o n positions are o c c u p i e d b y t h e O M P A m o l e 2

cules w h i l e t h e r e m a i n i n g t w o ( or m o r e ) positions are p r o b a b l y o c c u p i e d b y water molecules.


3+

Proton N M R Shifts.

T h e p r o t o n N M R spectra f o r several d i a m a g -

n e t i c rare e a r t h complexes

of O M P A

are s h o w n i n F i g u r e 3, a n d t h e

d a t a are t a b u l a t e d i n T a b l e I I I . T h e p r o t o n N M R s p e c t r u m of free O M P A contains a d o u b l e t w h i c h is c a u s e d b y c o u p l i n g b e t w e e n t h e p h o s p h o r u s

-180

-170

cps Figure

3.

RELATIVE

Proton Magnetic

-160

TO

-150

TMS, 60 Mc

Resonance Spectra OMPA

PROBE

of Lanthanide

Complexes of

OMPA La(ClOj ) · 4 OMPA • — · — · La(ClO ) · 3 OMPA · 2 H0 Y(C10 ) · 3 OMPA · 2 H 0 t 3

h 3

U S

2

2


2.

JOESTEN AND JACOB

Pyrophosphate

21

Derivatives

a n d the h y d r o g e n ( 2 ) . I n the c o m p l e x e s of O M P A t h e d o u b l e t is s h i f t e d downfield i n increasing order: L a ( C 1 0 ) 3 • 4 O M P A =

Mg(C10 ) 4

4

OMPA < La(C10 ) 4

*3 OMPA < Y(C10 )

3

4

3

· 3 OMPA.

2

*3

Although the

c h e m i c a l shifts a r e q u i t e s m a l l , t h e y a r e outside e x p e r i m e n t a l error. T h e d o n o r sites o f the l i g a n d i n these c o m p l e x e s m u s t b e a r r a n g e d i n a m a n n e r w h i c h a l l o w s a l l of t h e protons to b e e q u i v a l e n t . T h e s h i f t i n g d o w n f i e l d c a n b e e x p l a i n e d as b e i n g c a u s e d b y i n c r e a s e d c o v a l e n t b o n d i n g b e t w e e n the m e t a l i o n a n d O M P A w i t h t h e strongest i n t e r a c t i o n f o r Y ( I I I ) .

This


c a n b e u n d e r s t o o d b y c o n s i d e r i n g t h e f o l l o w i n g shifts i n e l e c t r o n d e n s i t y ( o n l y o n e m e t h y l g r o u p is s h o w n ).

y „

ΙΟΙ

\

ν

ΙΟΙ

4 l

I

/

H— C ~ N—P - O - P — N i H

/

/

/

/ \

„

ΙΟΙ

\ -

•

H

I

I

I

NI

NI

\

/ \

/

/

H — C - N = P - 0 - P - N l T

ΝI \

ΙΟΙ

H

/

I

I Nl / \

T h e increase i n d —p

b o n d i n g i n t h e Ρ — Ν b o n d gives t h e n i t r o g e n a

p a r t i a l p o s i t i v e charge.

T h i s causes a d r a i n i n e l e c t r o n d e n s i t y f r o m t h e

%

C—Ν

%

a n d C — Η bonds.

T h e stronger t h e b o n d i n g of t h e p h o s p h o r y l

oxygens to t h e m e t a l i o n , t h e greater t h e d r a i n of e l e c t r o n d e n s i t y f r o m the C — Η bonds. T h e p r o t o n N M R d a t a f o r other O M P A c o m p l e x e s of d i a m a g n e t i c m e t a l ions a r e also i n c l u d e d i n T a b l e I I I f o r c o m p a r i s o n . T h e i n c r e a s i n g o r d e r of O M P A — m e t a l

i o n i n t e r a c t i o n as i n d i c a t e d b y N M R shifts is

Table III. Compound

Proton N M R D a t a Position of Doublet"

OMPA Mg(C10 ) · 3 OMPA La(C10 ) · 4 OMPA La(C10 ) · 3 OMPA · 2 H 0 Y(C10 ) · 3 OMPA · 2 H 0

-153, -164 -159, -170 -158, -169 -161, -172 -165, -176

NaC10 · O M P A LiC10 · 2 OMPA Ba(C10 ) · 2 OMPA Zn(C10 ) · 3 OMPA Cd(C10 ) · 3 OMPA

-156, -167 -157, -168 -157, -168 -160, -171 -160, -171

4

4

4

4

2

3

3

9

3

2

4

4

4

2

4

2

4

2

c.p.s.

" Relative to tetramethylsilane i n methylene chloride at 3 5 ° C .


22

LANTHANIDE/ACTINIDE

CHEMISTRY

< L i ( I ) — B a ( I I ) < M g ( I I ) < Zn(II) = C d ( I I ) < L a ( I I I )

Na(I) Y (III).

Actinide Chemistry

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