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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
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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
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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-
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
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
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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
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
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
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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
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
· 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
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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
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
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
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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
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
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.
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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
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
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
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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 .
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
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).
<
T h i s agrees w i t h t h e e x p e c t e d o r d e r of i n t e r a c t i o n f o r complexes
of these ions. Visible Spectral Data. • H
2
T h e v i s i b l e s p e c t r u m of P r ( C 1 0 ) 4
3
*3 OMPA
0 is s h o w n i n F i g u r e 4. S p e c t r a l d a t a for complexes of O M P A w i t h
Pr(III), Nd(III), Eu(III), Ho(III),
and Er(III)
are l i s t e d i n T a b l e
I V . I n g e n e r a l , t h e peaks f o r O M P A complexes a p p e a r at s l i g h t l y shorter w a v e l e n g t h s t h a n those r e p o r t e d f o r a q u o complexes
(7, 12).
This trend
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is opposite t h a t w h i c h has b e e n o b s e r v e d f o r complexes of r a r e e a r t h ions w i t h a l l l i g a n d s except D 0 a n d F " (15). 2
[ 400
ι 450
I 500
L2: 600
ι 550
WAVELENGTH, mu Figure 4.
Visible Spectrum
J0rgensen (8)
has p r o p o s e d
of Pr(ClO )
h s
· 3 OMPA
· H0 2
that t h e r e d shift o b s e r v e d
for most
complexes of rare e a r t h ions c a n b e u s e d as a measure of t h e a m o u n t of c o v a l e n t b o n d i n g present i n t h e m e t a l - l i g a n d b o n d ( n e p h e l a u x e t i c series ). S i n h a ( 1 5 ) has m o d i f i e d J0rgensen's m e t h o d of c a l c u l a t i n g t h e percent of c o v a l e n t c o n t r i b u t i o n s to t h e m e t a l - l i g a n d b o n d a n d has e x a m i n e d s p e c t r a l d a t a for several complexes of N d ( I I I ). T h e peaks f o r N d ( C 1 0 ) 3 4
• 3 OMPA
· H
2
0 i n m e t h a n o l are at s l i g h t l y shorter w a v e l e n g t h s t h a n
those r e p o r t e d f o r N d ( I I I ) i n m e t h a n o l (15). T h e s p e c t r u m of N d ( C 1 0 ) a 4
- 3 OMPA · H
2
0 i n acetone w a s also m e a s u r e d , a n d t h e peaks are a g a i n
s h i f t e d to s l i g h t l y shorter w a v e l e n g t h s .
I f these shifts are a n a c c u r a t e
measure of c o v a l e n t b o n d i n g , t h e b o n d i n g i n complexes of O M P A w i t h rare e a r t h ions m u s t b e essentially electrostatic.
Earlier work
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
with
2.
JOESTEN A N D JACOB
Pyrophosphate
Table I V .
Visible Spectral Data In
Compound
Pr(C10 ) 4
2
Nd(C10 )
3
Eu(C10 )
Ho(C10 )
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4
Er(C10 ) 4
ΤΠμ
€
442 467 479 591
6.3 2.9 4.0 1.4 0.6 0.3 0.5 1.6 3.0 1.8 5.3 10.3 9.1 0.4
· 3 OMPA ·H 0
430 468 476 510 522 526 (sh) 570 579 581 (sh) 683
3
· 3 OMPA · 2H 0
361 375 392 463
3
· 3 OMPA · 4H 0
359 381 385 418 421 (sh) 449 451 457 468 472 485 538 543 (sh) 641 655 (sh)
3.8 0.2 0.4 1.9 0.7 10.0 10.6 6.0 0.6 0.7 1.1 3.3 1.3 1.9 0.6
362 375 378 403 441 448 486 518 521 541 652
2.2 14.0 9.0 0.6 0.3 0.6 2.0 8.2 5.6 0.5 1.7
4
4
In Acetone
Methanol
λ
· 3 OMPA ·H 0
3
3
2
2
2
· 3 OMPA · 2H 0 2
23
Derivatives
ΤΠμ
λ
c
428 468 474 508 520 523 (sh) 568 575 577 682
0.5 0.3 0.4 1.6 3.1 1.9 6.8 12.7 10.9 0.4
358 380 382 416 419 (sh) 448 452 457 466 471 484 536 541 (sh) 639 653 (sh)
6.2 0.3 0.4 2.3 0.6 15.7 16.7 10.7 0.8 0.9 1.3 4.0 1.5 2.1 0.6
0.5 0.3 2.9 0.4
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
24
L A N T H A N I D E / A C T I N I D E
C H E M I S T R Y
N i ( C 1 0 ) 2 ' 3 O M P A s u p p o r t s this c o n c l u s i o n s i n c e t h e l i g a n d field p a 4
rameters c a l c u l a t e d f o r t h e N i ( I I ) c o m p l e x p l a c e O M P A at t h e l o w e r e n d of b o t h t h e s p e c t r o c h e m i c a l a n d n e p h e l a u x e t i c series ( 6 ) .
Summary The
rare e a r t h c o m p l e x e s o f 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 are t h e
first examples of i s o l a t e d c o m p l e x e s w i t h rare e a r t h ions c o o r d i n a t e d to
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the p y r o p h o s p h a t e l i n k a g e .
E x p e r i m e n t a l e v i d e n c e supports t h e c o o r d i
n a t i o n 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 w i t h a d d i t i o n a l c o o r d i n a t i o n positions o c c u p i e d b y w a t e r .
Literature Cited
(1) Bauer, H., Blanc, J., Ross, D. L., J. Am. Chem. Soc. 86, 5125 (1964). (2) Cowley, A. H., Pinnell, R. P.,J.Am. Chem. Soc. 87, 4454 (1965). (3) Cunningham, J. Α., Sands, D. E., Wagner, W. F., Inorg. Chem. 6, 499 (1967). (4) Hathaway, B. J., Underhill, A. E., J. Chem. Soc. 1961, 3091. (5) Joesten, M. D., Forbes, J. F., J. Am. Chem. Soc. 88, 5465 (1966). (6) Joesten, M. D., Nykerk, Κ. M., Inorg. Chem. 3, 548 (1964). (7) Jørgensen, C. K., Acta Chem. Scand. 11, 981 (1957). (8) Jørgensen, C. K., "Absorption Spectra and Chemical Bonding in Com plexes," pp. 143-145, Pergamon Press, 1962. (9) Melby, L. R., Rose, N. J., Abramson, E., Caris, J. C., J. Am. Chem. Soc. 86, 5117 (1964). (10) Miller, F. Α., Wilkins, C. H.,Anal.Chem. 24, 1253 (1952). (11) Moeller, T., Martin, D. F., Thompson, L. C., Ferrus, R., Feistel, G. R., Randall, W. J., Chem. Rev. 65, 1 (1965). (12) Moeller, T., Horwitz, E. P., J. Inorg. Nucl. Chem. 12, 49 (1959). (13) Pavkovic, S. F., Meek, D. W., Inorg. Chem. 4, 1091 (1965). (14) Popp, C. J., Joesten, M. D., Inorg. Chem. 4, 1418 (1965). (15) Sinha, S. P., Spectrochim. Acta 22, 57 (1966). (16) Starke, K.,J.Inorg. Nucl. Chem. 11, 77 (1959). (17) Wickenden, A. E., Krause, R. Α., Inorg. Chem. 4, 404 (1965). RECEIVED October 4, 1966.
Fields and Moeller; Lanthanide/Actinide Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1967.
