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A PMR method of assigning the absolute configurations of the diastereomers of the bis(oxalato)(R-propylenediamine) cobaltate(III) ion
INORG.
NUCL.
CIIEM
LETTERS
Vol.
6,
pp.
907o911,
1970.
Pergamon
Press.
Printed in Great Britain.
A PMR METHOD OF ASSIGNING THE ABSOLUTE CONFIGURATIONS OF THE DIASTEREOMERS OF THE BIS(OXAI,ATO)(R- PROPYLENEDIAMINE)
Leon Department
C O B A L T A T E ( I I I ) ION
G.
Stadtherr and ,John G. BrushmiIler of Chemistry, University of North Dakota Grand Forks, North Dakota 58201 (Received 22 June 1970)
The absolute configurations complexes
of a n u m b e r
of e o b a l t ( I I I ) c o o r d i n a t i o n
containing the ligand R-propylenediamine
comparing their circular (-)D-/--C°(R-pn)3-/3+
diehroism
spectra
have been assigned by
(CD) 1 t o t h a t of t h e
ion w h o s e a b s o l u t e c o n f i g u r a t i o n is k n o w n f r o m X - r a y
d i f f r a c t i o n d a t a . 2, 3 T h e CD m e t h o d h a s b e e n h i g h l y s u c c e s s f u l the absolute configurations symmetry,
of t r i c h e l a t e d
cobalt(III) complexes
b u t it is n o t s t r i c t l y a p p l i c a b l e t o t r i c h e l a t e d
symmetry
(i.e.,
C 1)because
a r e no l o n g e r s y m m e t r y pmr spectra
determined.
assign the absolute configurations
significant differences pmr spectrum
4
of N a f f C o ( R - p n ) ( o x ) 2 - /
shown
in Figure
conformation positions
7-9
can be used to
of t h e c o m p l e x i o n s .
of t h e d i a s t e r e o m e r s in t h e m e t h y l ,
of N a / - C o ( R - p n ) ( o x ) 2 ~ s h o w
methylene,
and m e t h i n e r e g i o n s . is c o m p l e x ,
g i v e s r i s e t o an A B C X 3 s p e c t r u m 6 (the a m i n e h y d r o g e n s
this discussion
c o m p l e x e s w i t h low
In t h i s n o t e we w i s h t o s h o w how t h e
of c o o r d i n a t e d R - p r o p y l e n e d i a m i n e
quickly deuterate
R-propylenediamine
in both diastereomers,
on the chelate
ring.
coordinates
the A and C protons
A I00 MHz 907
spectrum
The
the ligand
is m e a s u r e d ) .
t h e p r o t o n s on c o o r d i n a t e d R - p r o p y l e n e d i a m i n e Because
5
of p r o p y l e n e d i a m i n e
in t h e D 2 0 s o l v e n t in w h i c h t h e s p e c t r u m
I.
with high
in t h e s e c o m p l e x e s t h e e l e c t r o n i c t r a n s i t i o n s
of t h e d i a s t e r e o m e r s
The pmr spectra
in p r e d i c t i n g
of each
For
are labeled as in the \ occupy
axial
diastereomer
was
BIS(OXALATO)(R-PROPYLENEDIAMINE) COBALT(lID ION
908
Vol. 6, No. 12
o b t a i n e d , the m e t h y l s i g n a l was d e c o u p l e d f r o m the m e t h i n e s i g n a l s o t h a t the c o m p l e x A B C X 3 s p e c t r u m c o l l a p s e d to a r a t h e r s i m p l e ABC s p e c t r u m , which could be a n a l y z e d .
The ABC s p e c t r u m of e a c h d i a s t e r e o m e r w a s a n a l y z e d
u s i n g the m e t h o d of G a r b i s c h 10 and the p m r p a r a m e t e r s T a b l e I.
o b t a i n e d a r e g i v e n in
The c o u p l i n g c o n s t a n t s o b t a i n e d f r o m t h e a n a l y s e s of the s p e c t r a
a r e in good a g r e e m e n t with t h o s e r e p o r t e d in the l i t e r a t u r e f o r c o o r d i n a t e d propylenediamine,
6
and the c a l c u l a t e d t h e o r e t i c a l s p e c t r a fit v e r y w e l l with
the e x p e r i m e n t a l s p e c t r a .
An e x a m i n a t i o n of the d a t a in T a b l e I s h o w s t h a t
the c h e m i c a l s h i f t s of t h e A and C p r o t o n s a r e s i g n i f i c a n t l y d i f f e r e n t in the two d i a s t e r e o m e r s ,
w h e r e a s the c h e m i c a l s h i f t s of t h e m e t h y l and B p r o t o n s
a r e v e r y n e a r l y t h e s a m e in t h e d i a s t e r e o m e r s . T A B L E I. Parameter
P M R D A T A F O R THE DIA~STEREOMERS O F Na ( C o ( R - pn)(ox) 2 7 (+)D i s o m e r
(-)D i s o m e r
VA ( m e t h i n e )
3.02
3. 18
VB
2.67
2.68
2.39
2.50
I. 32
I. 30
0.28 0.63
0. 18 0.68
4 . 2 Hz
5 . 0 Hz
VC AB JAB
(methylene}
JBC
12.0 Hz
10, 2 Hz
JAC
- 12.2 Hz
- 12.3 Hz
JAX
6 . 3 Hz
6 . 3 Hz
a A l l c h e m i c a l s h i f t s a r e g i v e n in p p m f r o m the i n t e r n a l r e f e r e n c e DSS. T h e c h e m i c a l s h i f t s of the A and C p r o t o n s can be u n d e r s t o o d in t e r m s of the m a g n e t i c a n i s o t r o p y a s s o c i a t e d with t h e C - - O s i n g t e bond of th~ c o o r d i n a t e d o x a l a t e g r o u p s . 11, 12 In the A a b s o l u t e c o n f i g u r a t i o n of t h e c o m p l e x ion the A and C p r o t o n s a r e l o c a t e d j u s t off a l i n e d r a w n a l o n g the C--
O s i n g l e bond of t h e o x a l a t e g r o u p .
T h i s r e g i o n is t h e d e s h i e l d i n g r e g i o n
a s s o c i a t e d with the m a g n e t i c a n i s o t r o p y due to t h e C - - O s i n g l e bond ( s e e
Vol. 6, No. 12
BIS(OXALATO)(R-PROPYLENEDIAMINE) COBALT(Ill) ION
909
0
I1
O..c,/C~o o ~ ^.L,;/01. . . ~ C\..o/ HC O
/c
0
II
\c~O
! ~~__co~O/ HA F i g u r e 1.
Bisoxalato-R-propylenediaminecobaltate(III) diastereomers
showing the d i f f e r e n t s h i e l d i n g of the HA and H C p r o t o n s . F i g u r e 1).
In the A a b s o l u t e c o n f i g u r a t i o n of the c o m p l e x ion, the A and C
p r o t o n s a r e l o c a t e d well above lines d r a w n along the C - - O s i n g l e bonds of
910
BIS(OXALATO)(RopROPYLENEDIAMINE) COBALT(lID ION
the oxalate groups,
Yol. 6, No. 12
a n d h e n c e t h e p r o t o n s l o c a t e d in t h i s p o s i t i o n w i l l n o t b e
deshielded by the magnetic anisotropy associated
with the C -- O bond.
H e n c e , t h e A a n d C p r o t o n s in t h e A a b s o l u t e c o n f i g u r a t i o n of t h e c o m p l e x i o n s h o u l d b e d e s h i e l d e d r e l a t i v e t o t h e A a n d C p r o t o n s of t h e A a b s o l u t e c o n f i g u r at ion. O n t h e b a s i s of t h e m a g n e t i c a n i s o t r o p y a r g u m e n t s d a t a in T a b l e I, t h e (+)D i s o m e r configuration and the (-)D isomer
and using the pmr
may be assigned to the A absolute m a y b e a s s i g n e d t o t h e /x a b s o l u t e
configuration. T h e B p r o t o n a n d t h e m e t h y l p r o t o n s o c c u p y e q u a t o r i a l p o s i t i o n s on the chelate ring and are remotely region associated
located with respect
to the deshielding
with the C -- O bond, hence their chemical shifts should not
d i f f e r g r e a t l y in t h e t w o d i a s t e r e o m e r s .
T h e d a t a in T a b l e I s h o w s t h a t t h e
B p r o t o n and t h e m e t h y l p r o t o n s h a v e n e a r l y t h e s a m e c h e m i c a l s h i f t s in both isomers. T h e a b s o l u t e c o n f i g u r a t i o n s a s s i g n e d on t h e b a s i s of m a g n e t i c anisotropy arguments
a r e in a g r e e m e n t
with the assignments
made by the
1
o p t i c a l CD m e t h o d .
ACKNOWLEDGEMENTS This work was supported by a University Faculty Research N. D. E . A . Research
Grant.
of N o r t h D a k o t a
A d d i t i o n a l f i n a n c i a l s u p p o r t in t h e f o r m of an
F e l l o w s h i p ( G r a n t No. 6 5 - 2 1 5 9 t o L. G. S. ) and a H i l l S u m m e r Professorship
spectra were measured
(to J. G. B. ) i s g r a t e f u l l y a c k n o w l e d g e d . on a s p e c t r o m e t e r
purchased
(GP-3642) and special thanks are due to the Procter f o r t h e 100 M H z s p e c t r o m e t e r
The 60MHz
in p a r t b y N S F f u n d s and G a m b l e C o m p a n y
work.
REFERENCES 1) A. J. M c C a f f e r y , J. C h e m .
Soc.,
S. F . M a s o n ,
B. J. N o r m a n ,
S e c t . A , 1304 (1968).
a n d A. M. S a r g e s o n ,
Vol. 6, No. 12
BIS(OXALATO)(R-PROPYLENEDIAMINE) COBALT(Ill) ION
2) Y. Saito, H. Iwasaki, and H. Ota, Bull. Chem. Soc. J a p . ,
911
3__66, 1543 (1963).
3) H. Iwasaki and Y. Saito, ibid, 39, 92 (1966). 4) R. D. G i l l a r d in " P h y s i c a l Methods in A d v a n c e d I n o r g a n i c C h e m i s t r y , " H. A. O. Hill and P. Day, E d . , I n t e r s c i e n c e P u b l i s h e r s , New Y o r k , N. Y . ,
1968, Chap. 5.
5) J. G. B r u s h m i l l e r and L. G. S t a d t h e r r , Inorg. Nucl. Chem. L e t t e r s , 3, 525 (1967). 6) S. Yano, H. Ito, Y. Koike, J. F u j i t a and K. Saito, Bull Chem. Soc. J a m . , 42, 3184 (1969). 7) E. J. C o r e ¥ and J. C. B a i l a r ,
Jr.,
J. A m e r . Chem. S o c . , 81, 2.620 (1959)
8) A. M. S a r g e s o n in "Chelating Agents and Metal C h e l a t e s , " F. P. D w y e r and D. P. M e l l o r , E d . , A c a d e m i c P r e s s ,
New Y o r k and London, 1964,
Chap. 5. 9) A. M. S a r g e s o n in " T r a n s i t i o n Metal C h e m i s t r y , " R. L. C a r l i n , E d . , M a r c e l D e k k e r , I n c . , New York, N. Y., Vol. 3, p 303. 10) E. W. G a r b i s c h , J. Chem. E d u c . , 45..., 311 (1968). 11) The m a g n e t i c a n i s o t r o p y a s s o c i a t e d with a C -
N bond is d i s c u s s e d by
L. N. S c h o e n b e r g , D. W. Cooke, and C. F. Liu, Inorg_ C h e m . , 7, 2386 (1968); J. I. L e g g and D. W. Cooke, ibid., 4, 1576 (1965). 12) E. A. B e r e n d s , Ph. D. D i s s e r t a t i o n , G r a n d F o r k s , N o r t h Dakota, 1970.
The U n i v e r s i t y of North Dakota,
NUCL.
CIIEM
LETTERS
Vol.
6,
pp.
907o911,
1970.
Pergamon
Press.
Printed in Great Britain.
A PMR METHOD OF ASSIGNING THE ABSOLUTE CONFIGURATIONS OF THE DIASTEREOMERS OF THE BIS(OXAI,ATO)(R- PROPYLENEDIAMINE)
Leon Department
C O B A L T A T E ( I I I ) ION
G.
Stadtherr and ,John G. BrushmiIler of Chemistry, University of North Dakota Grand Forks, North Dakota 58201 (Received 22 June 1970)
The absolute configurations complexes
of a n u m b e r
of e o b a l t ( I I I ) c o o r d i n a t i o n
containing the ligand R-propylenediamine
comparing their circular (-)D-/--C°(R-pn)3-/3+
diehroism
spectra
have been assigned by
(CD) 1 t o t h a t of t h e
ion w h o s e a b s o l u t e c o n f i g u r a t i o n is k n o w n f r o m X - r a y
d i f f r a c t i o n d a t a . 2, 3 T h e CD m e t h o d h a s b e e n h i g h l y s u c c e s s f u l the absolute configurations symmetry,
of t r i c h e l a t e d
cobalt(III) complexes
b u t it is n o t s t r i c t l y a p p l i c a b l e t o t r i c h e l a t e d
symmetry
(i.e.,
C 1)because
a r e no l o n g e r s y m m e t r y pmr spectra
determined.
assign the absolute configurations
significant differences pmr spectrum
4
of N a f f C o ( R - p n ) ( o x ) 2 - /
shown
in Figure
conformation positions
7-9
can be used to
of t h e c o m p l e x i o n s .
of t h e d i a s t e r e o m e r s in t h e m e t h y l ,
of N a / - C o ( R - p n ) ( o x ) 2 ~ s h o w
methylene,
and m e t h i n e r e g i o n s . is c o m p l e x ,
g i v e s r i s e t o an A B C X 3 s p e c t r u m 6 (the a m i n e h y d r o g e n s
this discussion
c o m p l e x e s w i t h low
In t h i s n o t e we w i s h t o s h o w how t h e
of c o o r d i n a t e d R - p r o p y l e n e d i a m i n e
quickly deuterate
R-propylenediamine
in both diastereomers,
on the chelate
ring.
coordinates
the A and C protons
A I00 MHz 907
spectrum
The
the ligand
is m e a s u r e d ) .
t h e p r o t o n s on c o o r d i n a t e d R - p r o p y l e n e d i a m i n e Because
5
of p r o p y l e n e d i a m i n e
in t h e D 2 0 s o l v e n t in w h i c h t h e s p e c t r u m
I.
with high
in t h e s e c o m p l e x e s t h e e l e c t r o n i c t r a n s i t i o n s
of t h e d i a s t e r e o m e r s
The pmr spectra
in p r e d i c t i n g
of each
For
are labeled as in the \ occupy
axial
diastereomer
was
BIS(OXALATO)(R-PROPYLENEDIAMINE) COBALT(lID ION
908
Vol. 6, No. 12
o b t a i n e d , the m e t h y l s i g n a l was d e c o u p l e d f r o m the m e t h i n e s i g n a l s o t h a t the c o m p l e x A B C X 3 s p e c t r u m c o l l a p s e d to a r a t h e r s i m p l e ABC s p e c t r u m , which could be a n a l y z e d .
The ABC s p e c t r u m of e a c h d i a s t e r e o m e r w a s a n a l y z e d
u s i n g the m e t h o d of G a r b i s c h 10 and the p m r p a r a m e t e r s T a b l e I.
o b t a i n e d a r e g i v e n in
The c o u p l i n g c o n s t a n t s o b t a i n e d f r o m t h e a n a l y s e s of the s p e c t r a
a r e in good a g r e e m e n t with t h o s e r e p o r t e d in the l i t e r a t u r e f o r c o o r d i n a t e d propylenediamine,
6
and the c a l c u l a t e d t h e o r e t i c a l s p e c t r a fit v e r y w e l l with
the e x p e r i m e n t a l s p e c t r a .
An e x a m i n a t i o n of the d a t a in T a b l e I s h o w s t h a t
the c h e m i c a l s h i f t s of t h e A and C p r o t o n s a r e s i g n i f i c a n t l y d i f f e r e n t in the two d i a s t e r e o m e r s ,
w h e r e a s the c h e m i c a l s h i f t s of t h e m e t h y l and B p r o t o n s
a r e v e r y n e a r l y t h e s a m e in t h e d i a s t e r e o m e r s . T A B L E I. Parameter
P M R D A T A F O R THE DIA~STEREOMERS O F Na ( C o ( R - pn)(ox) 2 7 (+)D i s o m e r
(-)D i s o m e r
VA ( m e t h i n e )
3.02
3. 18
VB
2.67
2.68
2.39
2.50
I. 32
I. 30
0.28 0.63
0. 18 0.68
4 . 2 Hz
5 . 0 Hz
VC AB JAB
(methylene}
JBC
12.0 Hz
10, 2 Hz
JAC
- 12.2 Hz
- 12.3 Hz
JAX
6 . 3 Hz
6 . 3 Hz
a A l l c h e m i c a l s h i f t s a r e g i v e n in p p m f r o m the i n t e r n a l r e f e r e n c e DSS. T h e c h e m i c a l s h i f t s of the A and C p r o t o n s can be u n d e r s t o o d in t e r m s of the m a g n e t i c a n i s o t r o p y a s s o c i a t e d with t h e C - - O s i n g t e bond of th~ c o o r d i n a t e d o x a l a t e g r o u p s . 11, 12 In the A a b s o l u t e c o n f i g u r a t i o n of t h e c o m p l e x ion the A and C p r o t o n s a r e l o c a t e d j u s t off a l i n e d r a w n a l o n g the C--
O s i n g l e bond of t h e o x a l a t e g r o u p .
T h i s r e g i o n is t h e d e s h i e l d i n g r e g i o n
a s s o c i a t e d with the m a g n e t i c a n i s o t r o p y due to t h e C - - O s i n g l e bond ( s e e
Vol. 6, No. 12
BIS(OXALATO)(R-PROPYLENEDIAMINE) COBALT(Ill) ION
909
0
I1
O..c,/C~o o ~ ^.L,;/01. . . ~ C\..o/ HC O
/c
0
II
\c~O
! ~~__co~O/ HA F i g u r e 1.
Bisoxalato-R-propylenediaminecobaltate(III) diastereomers
showing the d i f f e r e n t s h i e l d i n g of the HA and H C p r o t o n s . F i g u r e 1).
In the A a b s o l u t e c o n f i g u r a t i o n of the c o m p l e x ion, the A and C
p r o t o n s a r e l o c a t e d well above lines d r a w n along the C - - O s i n g l e bonds of
910
BIS(OXALATO)(RopROPYLENEDIAMINE) COBALT(lID ION
the oxalate groups,
Yol. 6, No. 12
a n d h e n c e t h e p r o t o n s l o c a t e d in t h i s p o s i t i o n w i l l n o t b e
deshielded by the magnetic anisotropy associated
with the C -- O bond.
H e n c e , t h e A a n d C p r o t o n s in t h e A a b s o l u t e c o n f i g u r a t i o n of t h e c o m p l e x i o n s h o u l d b e d e s h i e l d e d r e l a t i v e t o t h e A a n d C p r o t o n s of t h e A a b s o l u t e c o n f i g u r at ion. O n t h e b a s i s of t h e m a g n e t i c a n i s o t r o p y a r g u m e n t s d a t a in T a b l e I, t h e (+)D i s o m e r configuration and the (-)D isomer
and using the pmr
may be assigned to the A absolute m a y b e a s s i g n e d t o t h e /x a b s o l u t e
configuration. T h e B p r o t o n a n d t h e m e t h y l p r o t o n s o c c u p y e q u a t o r i a l p o s i t i o n s on the chelate ring and are remotely region associated
located with respect
to the deshielding
with the C -- O bond, hence their chemical shifts should not
d i f f e r g r e a t l y in t h e t w o d i a s t e r e o m e r s .
T h e d a t a in T a b l e I s h o w s t h a t t h e
B p r o t o n and t h e m e t h y l p r o t o n s h a v e n e a r l y t h e s a m e c h e m i c a l s h i f t s in both isomers. T h e a b s o l u t e c o n f i g u r a t i o n s a s s i g n e d on t h e b a s i s of m a g n e t i c anisotropy arguments
a r e in a g r e e m e n t
with the assignments
made by the
1
o p t i c a l CD m e t h o d .
ACKNOWLEDGEMENTS This work was supported by a University Faculty Research N. D. E . A . Research
Grant.
of N o r t h D a k o t a
A d d i t i o n a l f i n a n c i a l s u p p o r t in t h e f o r m of an
F e l l o w s h i p ( G r a n t No. 6 5 - 2 1 5 9 t o L. G. S. ) and a H i l l S u m m e r Professorship
spectra were measured
(to J. G. B. ) i s g r a t e f u l l y a c k n o w l e d g e d . on a s p e c t r o m e t e r
purchased
(GP-3642) and special thanks are due to the Procter f o r t h e 100 M H z s p e c t r o m e t e r
The 60MHz
in p a r t b y N S F f u n d s and G a m b l e C o m p a n y
work.
REFERENCES 1) A. J. M c C a f f e r y , J. C h e m .
Soc.,
S. F . M a s o n ,
B. J. N o r m a n ,
S e c t . A , 1304 (1968).
a n d A. M. S a r g e s o n ,
Vol. 6, No. 12
BIS(OXALATO)(R-PROPYLENEDIAMINE) COBALT(Ill) ION
2) Y. Saito, H. Iwasaki, and H. Ota, Bull. Chem. Soc. J a p . ,
911
3__66, 1543 (1963).
3) H. Iwasaki and Y. Saito, ibid, 39, 92 (1966). 4) R. D. G i l l a r d in " P h y s i c a l Methods in A d v a n c e d I n o r g a n i c C h e m i s t r y , " H. A. O. Hill and P. Day, E d . , I n t e r s c i e n c e P u b l i s h e r s , New Y o r k , N. Y . ,
1968, Chap. 5.
5) J. G. B r u s h m i l l e r and L. G. S t a d t h e r r , Inorg. Nucl. Chem. L e t t e r s , 3, 525 (1967). 6) S. Yano, H. Ito, Y. Koike, J. F u j i t a and K. Saito, Bull Chem. Soc. J a m . , 42, 3184 (1969). 7) E. J. C o r e ¥ and J. C. B a i l a r ,
Jr.,
J. A m e r . Chem. S o c . , 81, 2.620 (1959)
8) A. M. S a r g e s o n in "Chelating Agents and Metal C h e l a t e s , " F. P. D w y e r and D. P. M e l l o r , E d . , A c a d e m i c P r e s s ,
New Y o r k and London, 1964,
Chap. 5. 9) A. M. S a r g e s o n in " T r a n s i t i o n Metal C h e m i s t r y , " R. L. C a r l i n , E d . , M a r c e l D e k k e r , I n c . , New York, N. Y., Vol. 3, p 303. 10) E. W. G a r b i s c h , J. Chem. E d u c . , 45..., 311 (1968). 11) The m a g n e t i c a n i s o t r o p y a s s o c i a t e d with a C -
N bond is d i s c u s s e d by
L. N. S c h o e n b e r g , D. W. Cooke, and C. F. Liu, Inorg_ C h e m . , 7, 2386 (1968); J. I. L e g g and D. W. Cooke, ibid., 4, 1576 (1965). 12) E. A. B e r e n d s , Ph. D. D i s s e r t a t i o n , G r a n d F o r k s , N o r t h Dakota, 1970.
The U n i v e r s i t y of North Dakota,