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Orbital Symmetry Analysis of Intersystem Crossing during Thermal Isomerization of Tetrahedral to Planar Nickel (II) Complexes.

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n e c e s s a r i l y be a s s o c i a t e 9 w i t h a d e c r e a s e in :'ie
Dieses Manuskript ist
zu zitieren als
Angew. Chem. Suppl.
This manuscript is
to be cited as
Angew. Chem. Suppl.
1982,622- 634
1982,622-634
of
maInitude
-ASc.
I r e v i o u s a t t e m p t s t o c l a s s i f y t h i s i s o m e r i z a i i o n as
" a l i o w e d " or " f o r b i d i e n " by syml?etry have bee:> i n c o n c l u Thus Caton /13,',
sive:
Verlag Chemie GmbH, D-6940 Weinheim, 1982
0721C
-4227/82/04040646S
r i i i t a l Lymmetry
02.50/0
A n a l y s i s o f I n t e r s y s t e r Crossinrr
a d a p t i n g t h e >;oodward-::offmann
b i t a l c o r r e l a t i o n procedl;re /14/
or-
t o the spin-cmservative
i s o m e r i z a t i o n , c l a s s i f i e d i t as " a l l o w e d " , whereupon White-
-
4 u r i n c Thermal I s o m e r i z a t i o n of T e t r a h e 2 r a l t o
s i d e s /I?/
~___
i l a n a r :lickel(:I)
___-
Somplexes
p o i n t e d out t h a t , s i n c e state-symmetry
i s not
f *
conserved d u r i n g t h e p r o c e s s , it i s necessaril:?
e d " . F e a r s o n /16/ concluded from Bader's
3y 1'. A a i t a i H a l e v i l a n ? Ru3olf Knorr
'
/17/
"disallow-
> r i t e r i a , bas-
ed on J a h n - T e l l e r e f f e c t s , t h a t i s o m e r i z a t i o n s h o u l d be f a c i l e i u e t o t h e p r e s e n c e of low-lying unoccupied o r b i t a l s
which have t h e p r o p e r symmetry t o c o u p l e v i b r o n i c a l l y w i t h
Pruf.
3r. E.
i i a l e v i , 1nstitur.e
A.
U n i v e r s i t y o f i'unich ;
Shemistry,
Haifa
permanent a d i r e s s :
-
Technion
52 OC(:,
of Organic C h e m i s t r y ,
3 e p a r t m e n t of
I s r a e l I n s t i t u t e of Technology,
was t r e a t e d by Lee /18/
change i n s p i n - m u l t i p l i c i t y
a p p l y i n g L i n ' s /19/
that
Israel
Prof. Jr. 2. Knorr,
t h e occupied o r b i t a l s a l o n g t h e r e a c t i o n c o o r d i n a t e . The
r u l e s for i n t e r s y s t e m cros:;ing,
who,
found
"no d e f i n i t e c o n c l u s i o n p e r t a i n i n g t o a l l o w e d n e s s c a n
be drawn from symmetry c o n s i d e r a t i o n s a l o n e f o r t h r e e of t h e
I n s t i t u t e of O r g a n i c C h e m i s t r y ,
U n i v e r s i t y o f Plunich, K a r l s t r . 2 3 , 3-800O Punich 2 , Germany
n i n e p o s s i b l e pathways of i s o m e r i z a t i o n "
and t h a t
"compu-
t a t i o n a l e f f o r t i s r e q u i r e d f o r d e t e r m i n i n g t h e allowed-
**
T h i s work was s u p p o r t e d by ? r a n t s from t h e Kinerva
Foundation
(.GO
A.
?.:
frorr. t h e Ponds d e r Zhemischen
Ji.)*
l n d u s t r i e , t h e Deutsche F o r s c h u n g s g e m e i n s c h a f t , and t h e
S t i f t u n g Volkswagenwerk
( t o R.
K.).
ness"
of t h e remaining s i x .
I n t h i s communication,
w e employ O r b i t a l C o n s e r v a t i o n
A n a l y s i s i n Maximum Symmetry (OCAMS) / 2 0 / , a s e x t e n d e d t o
r e a c t i o n s which do n o t c o n s e r v e s p i n - m u l t i p l i c i t y
Its
/2q/.
u s e t o d a t e h a s been r e s t r i c t e d t o commutative symmetry
p o i n t groups,
i. e.
representations.
t h o s e which have o n l y n o n - 9 e g e n e r a t e
The a n a l y s i s of symmetry-brraxlng a l o n g
- 622 -
-
B i v a l e n t n i c k e l (3d8) may form ( p s e u d o ) t e t r a h e d r a l ,
magnetic ( h i q h - s p i n t r i p l e t ) o r p l a n a r , d i a m a y n e t i c
s p i n sin.:let)
spectra.
para(low-
complexes, which show v e r y d i f f e r e n t '
H
NMR
AlthouKh t h e i n t e r c o n v e r s i o n of t h e two i s o m e r s r e -
q u i r e s a s p i n change of A S
=
1 and m i g h t , t h e r e f o r e , be ex-
p e c t e d t o be a slow p r o c e s s , numerous examples / ? , 2 /
such t r i p l e t - t o - s i n g l e t
of
i n t e r c o n v e r s i o n s have been r e p o r t e d
624
-
d e g e n e r a t e d i s p l a c e m e n t c o o r d i n a t e s , r e c e n t l y p u b l i s h e d by
Murray-Rust,
Biirgi and D u n i t z / 2 2 / , q r e a t l y f a c i l i t a t e s t h e
a p p l i c a t i o n of OCAMS t o r e a c t i o n s l i k e t h e i s o m e r i z a t i o n
under c o n s i d e r a t i o n .
A l l of t h e p r e v i o u s i n v e s t i q a t o r s r e c o g n i z e 3 t h a t t h e r e -
a c t i o n c o o r d i n a t e s t a r t s a l o n g a n u c l e a r displacement t h a t
b e l o n g s t o t h e r e p r e s e n t a t i o n Z of t h e t e t r a h e d r a l symmetry
t o be immeasurably f a s t , and i n o n l y a few c a s e s c o u l d t h e
p o i n t I r o u p , Td.
two s p e c i e s be r e s o l v e d , or e n a n t i o m e r i c s t a b i l i t y demon-
t h e C a r t e s i a n a x e s and f o c u s i n g a t t e n t i o n on t h e z - a x i s ,
the
two d e g e n e r a t e modes of E-symmetry can be d e s c r i b e d /22a/
as
s t r a t e d , by 'H
NMR s p e c t r o s c o p y .
Tetrahedral-t?-planar
i s o m e r i z a t i o n s of t h i s k i n 3 a r e
c h a r a c t e r i z e d by r e l a t i v e l y low e n t h a l p i e s /3-7/
t i o n (A!t* c a . 6
-
of activa-
13 kcal/mol), but s t e r i c r e p u l s i o n s i n
t h e p l a n a r s t a t e can r e s u l t i n a h i E h e r p o t e n t i a l b a r r i e r
(At!*
= 22.5
kcal/mol)
/a/.
The e n t r o r i e s ( A S * )
of a c t i v a t i -
o n , a c a i n measured from t h e t e t r a h e d r a l ground s t a t e , were
found t o be more n e r a t i v e t h a n
c h e l a t e d n i c k e l N4-complexes
r a n c i n : from
z e r o e.u.)
-6 t o +9 e.u.
-10 c a l K-'
mo1-l
Tor b i s -
i n Fig. 1 t o be
Choosing t h e t h r e e e q u i v a l e n t S2-axes a s
( i ) Sa
,
a n u c l e a r motion which would even-
t u a l l y compress t h e l i a a n d s i n t o t h e x y - p l a n e ;
Sb
,a
and
(ii)
t w i s t , t e n d i n g t o p u t t h e l i q a n d s i n t o t h e xz-
que a x i s , compression a l o n g or t w i s t a b o u t e i t h e r of t h e
o t h e r two C2-axes would be e x p r e s s e d a s a l i n e a r combination
of Sa and
Sb.
/7,8/,whereas AS* v a l u e s
(an3 frequently quite close t o
have been r e p o r t e d /3-6/
f o r n i c k e l ( i 1 ) complexes
w i t h halo,ren atoms a s two of t h e c o o r d i n a t i n g l i g a n d s .
P r o c e s s e s which have a low e n t h a l p y of a c t i v a t i o n may be
s u s p e c t e d a p r i o r i o f b e i n g "allowed" by o r b i t a l symmetry
c o n s e r v a t i o n / 9 / . Thermal r e a c t i o n s i n which s p i n - m u l t i p l i c i t y is n o t conserved can have a low a c t i v a t i o n e n t h a l p y ,
S,
s,
(z-Compression)
b u t a r e g e n e r a l l y c h a r a c t e r i z e d by a more n e g a t i v e e n t r o p y
of a c t i v a t i o n /1@-12/; heavy atom s u b s t i t u t i o n would t h e n
F i q . 1.
The two 3 e q e n e r a t e
i n a t e t r a i e d r a l molecule
- 623
-
(or
t h e yz-) p l a n e . With t h i s p a r t i c u l a r c h o i c e of z a s t h e uni-
-
625
-
!e)
(z-Twist)
displacements
I t i s e v i d e n t t h a t Sa and Sb a r e t r u l v e q u i v a l e n r . o n l y f o r
i n f i n i t e s i m a l d e p a r t u r e s f r m t e t r a t e d r a l ?:eometr>-. T h e i r
If, f o r example, l i e -
chemical consequences a r e d i f f e r e n t :
ands
1 and 2
2
identical
c i s isomer
a r e i d e n t i c a l but; d i f f e r from t h e s i z i l a r l y
?. 1s
i n which
2,
and
Sa w i l l l e a d t o t h e
trans and
St t.; t h e
of t h e p l a n a r complex. I n a b i s - c h e l a t e d
ring-strain
2
joinei t o
3
and
5,
to
complex,
Sa i s p r e v e n t e d by
from s e r v i n g a s a r e a c t i o n c o o r d i n a t e f o r i s o -
n
m e r i z a t i o n , whereas Sb i s n o t .
I t i s p e r h a p s l e s s s e n e r a l i y r e c o g n i z e d t h a t Sa and Sb
,
a l t h o u g h c o u p l e d w i t h i n t h e s2me l e g e n e r a t e r e p r e s e n t a t i o n
E of Td
, differ i n
t h e i r symmetry p r o p e r t i e s . A t w i s t
Sb
to
a b o u t any of t h e t h r e e C2-axes r e d u c e s symrretry from Td
D2
,
kernel
t h e subgroup of Td which i s t h e
of E. Compress-
i o n Sa a l o n g any C2-axis r e t a i n s i t as t h e unique S4-axis
and two of t h e d i a s o n a l m i r r o r p l a n e s a s we!l;
t h e s e , toge-
,
t h e co-kernel
,
t h e r w i t h t h e e l e m e n t s o f D2
of E /22a/.
comprise D2d
S i m i i a r l y , s t a r t i n a from t h e s q u a r e - p l a n a r reo-
metry D t h ( t h e C4-axis
r e v e r s i n g Sa
,
t h e c o o r d i n a t e Sa'
l i e s along z),
,
t r a n s f o r m s l i k e Blu
,
N 0
N
n
whereas t h a t r e v e r s i n g
Sb b e l o n g s t o t h e r e d u c i b l e r e p r e s e n t a t i o n (ale
+ Ylu) / 2 3 / .
The c o r r e s p o n d e n c e d i a q r a m s f o r t h e t w o pathways a r e s e t
up i n Fig.
2. On i t s l e f t - h a n d s i d e , t h e Sa rouze i s a n a l y -
zed i n
(with t h e S4-axis alon$
2 ) ;
l a r g e s t common subgroup of Tl and D4,,D2
,
,
but can a l s o be a t t a i n e d s t e p w i s e :
-
-
D&-*
626
1 and 2
and between
i t i n t o D2h,
2
and 4 d e c r e a s e towards
which t r a n s f o r m s l i k e b,
and d e - c h e l a t i o n
W
Fig. 2.
Correspondence d i a g r a m s f o r t e t r a h e d r a l t o p l a n a r
L e f t s i d e : Along
l s o m e r i z a t i o n of n i c k e l ( I I ! complexes.
compression c o o r d i n a t e ( S a ) . - Right s i d e : Alona t w i s t coo r d i n a t e ( S b ) , wlth o r without c h e l a t i o n ( s e e t e x t )
-
-
?he t w i s t o f t h e r e s u l -
c o r r e s p o n d s t o c h e l a t i o n /24/.
t i n g bis-chelate,
$1
n
-
The f i r s t s t e p , Sil, i n which t t e a n g l e s
D2.
between l i g a n d s
90°,
The k e r n e l symmetry,
i s a c h i e v e d d i r e c t l y by t w i s t i n g of t h e t e t r a h e d r a l
complex a l o n g Sb
Td
D2d is, i n f a c t , t h e
N
i n t o D:h.
of D2d/25/,
takes
The r e v e r s e t w i s t o f
628
-
C o n v e r s e l y , compression d e s t a b i l i z e s t h e dxy o r b i t a l r e l a t i -
so that
ve t o dyz nnd d x z , which remain d e c e n e r a t e i n D:d,
e m b a r k a t i o n a l o n q Sa would i n i t i a l l y p r o d u c e t h e E
'
w l t h [...e2eb2]
state
confi\?uration /28/.
Tur.iin6 f i r s t t r t?ie t w i s t pathway Sb in Fig. 2 , we s e e
t h e p l a n a r complex c a n a l s o be accomplished i n two s t e p s : As
t h a t t t l r e e o f t h e f o u r doubly-occupied
shown on t h e r i g h t - h a n d
p l a n a r c o n p l e x have t h e same D2 r e p r e s e n t a t i o n s a s t h e t h r e e
from which t h e t w i s t (a,)
d u c e s symmetry t o D2h,
f u r t h e r t o D2.
s i d e of Fig. 2 , c h e l a t i o n (blB) r e reduces i t
Thus, t h e c o r r e s p o n d e n c e diagram for t h e Sb
pathway i s r e a d :
.= D2
Td
c a s e of a n o n - c h e l a t e ?
(D2h) e== D&.
For t h e
complex, t h e s r o u p l a b e l s e n c l o s e d in
idoubly-occupied
o r b i t a l s o f t h e ( p s e u d 0 ) t e t r a h e d r a l complex.
The i o u r t h , dyz
,
c o r r e s p o n d s w i t h one of t h e s l n g l y - o c c u p i -
ed o r D i t a l s ( b 3 ) , b u t t h e o t h e r ( b 2 ) c o r r e s p o n d s w i t h t h e
empty d x z o r b i t a l (b2g).
I f t h e Ground s t a t e of t h e ( p s e u -
p a r e n t h e s e s c a n be r e g a r d e d a s " v i r t u a l S y m T e t r i e s " , i n
do)tesrahedral
which t h e two i n t e r n a l bond a n g l e s , v a r y i n g a l o n g Sb between
same e l e c t r o n c o n f i g u r a t i o n ,
t e t r a h e d r a l and 90°,
along
Sil
a r e assumed t o d e c r e a s e i n f i n i t e s l m a l l y
j u s t before the t w i s t proper s e t s in.
complex were t h e o p e n - s h e l l
s i n g l e t of t h e
t i e d i r e c t p l a n a r i z a t i o n of
which h a s been c l a s s i f i e d a s " f o r b i d d e n " /27b/,
would r e q u i r e e x c i t a t i o n of a bl d i s t o r t i o n t o
The o r b i t a l sequence o f t h e p a r t l a l l y f i l l e d s e t of 3d orb i t a l s i n the closed-shell
3d o r b i t a l s in t h e
Fround s t a t e of t h e p l a n a r com-
OCAMS / 2 0 /
-
the
c o r r e s p o n d e n c e between d x z ( b 2 > and d y z ( b 3 ) , and f o r m a l l y
remove t h e " f o r b i d l e n n e s s " . Any such b,, d i s p l a c e m e n t , how-
t 2 v1-
p l e x i s not i m p o r t a n t for t h e p u r p o s e of q u a l i t a t i v e symi-e-
e v e r , i s d e r i v e d from one or more of t h e 'iigh-enercy
t r y a n a l y s i s / 2 5 / , e x c e p t f o r t h e w e l l e s t a b l i s h e d /23, 27/
o r a t i o n a l modes of t h e t e t r a h e f i r a i m o l e c u i e ; i t would r a i s e
f a c t t h a t t h e unoccupied o r b i t a l i s b2g, which p o i n t s d i -
t h e a c t i v a t i o n enerc-y of t h e p 1 a : i a r i z a t i o n which t h u s re-
r e c t l y t o t h e l i g a n d s (dxy or dxz f o r t h e complex i n t h e r y
mains " d i s a l l o w e d " .
o r xz p l a n e s , r e s p e c t i v e l y ) . Tiie >d o r b i t a l sequence of t h e
p s e u d o t e t r a h e d r a l complex depends on how t h e t 2 - l e v e l
LS
S i n c e t h e t r a n s f e r of a n e l e c t r o n between d
r a h e d r a l t r i g l e t and d
YZ
XZ
Of
the tet-
o f t h e p l a n a r s i n g l e t i s accompan-
s p l i t by t h e distortion away from Td symmetry. T h e o r e t l c a l
i e d by a chanqe of i t s s p i n , t h e p e r t u r b a t i o n o f symmetry
p r e d i c t i o n s / 2 3 , 27, 28/ of a 3A2
s p e c i e s b,, need n o t be t h e e x c i t a t i o n of a v i b r a t i o n a l mode,
t r o n c o n f i g u r a t i o n [...b$ee;)
ground s t a t e (wish e l e c -
i n D$d
f o r eloncated chelate
complexes have been c o n f i r e e d by s t r u c t u r a l a n a l y s i s /24/.
-
627
-
b u t can be a c i r c u l a s i o n of c h a r g e i n t h e xy-plane,
which
g e n e r a t e s a rcarmetic moment, a b o u t t h e z - a x i s and a l l o w s f o r -
-
629 -
mation o r a n n i h i l a t i o n of t h e z-component
of t h e s p i n t r i p -
Symmetry, Verlag ^ h e m e , Weinheim and Academic P r e s s ,
!iew Y or k 1970.
l e t w i t h c o n s e r v a t i o n of t o t a l ( o r b i t a l plus s p i n ) a n g u l a r
momen?um /21, 29/.
d e conclude, t h e r e f o r e , t h a t t h e spin-non
/ l o / D. C. Doetschmann, C. A. Hutchison, Jr., J. Chem. Phys.
z , 3964 (1972).
c o n s e r v a t i v e i s o m e r i z a t i o n i s "allowed", i n t h e s e n s e t h a t
a spin-orbit
couplin.; component e x i s t s which has t h e p r o p e r
symmetry 'b,
o f D2) t o p e r m i t t h e s p i n - f l i p
/11/ J. A.
t o o c c u r , and
/12/ C.
t h u s f a c i l i t a t e the t e t r a h e d r a l t o planar isomerization
xes alike.
of course
-
i s "allowed" l i k e w i s e , b u t
-
I).
Duncan, G. C. O'Connell,
M.
S.
Chem. SOC. 98, 2358 (1976).
Duncan, E. A.
SOC. 101, 2269
a l o n q t h e Sb pathway, i n b i s - c h e l a t e d and unchelated comple-
T h e compression pathway (S,)
Berson, C. D.
P l a t z , J. Am.
H a l e v i , C. T r i n d l e , J. Am.
Chem.
(1979).
90,
/13/
D.
/14/
Eaton based h i s a n a l y s i s , of t h i s and t h e r e l a t e d
o n l y f o r u n c h e l a t e d complexes: A s t h e t e t r a h e d -
R.
Eaton, 3. Am.
Chem. SOC.
4272 (1968).
&-
t r a n s i s o m e r i z a t i o n on t h e t h r e e p e r p e n d i c u l a r C2-axes
r a l t r i p l e t d i s t o r t s s l i g h t l y alonr: t h i s pathway s o as t o
r e t a i n e d a l o n g t h e D2 pathway, symmetry elements which
stabilize the E
'
do n o t " b i s e c t bonds made o r broken i n t h e p r o c e s s "
i n e of Dzd.
s t a t e , one e l e c t r o n i s i n b2 and t h e o t h e r
The p e r t u r b a t i o n r e q u i r e d t o induce one-elec-
( c f . p.
/9/).
31 of R e f .
z, 2395
t r o n correspondence between a b2 and a n e o r b i t a l would be
/15/ T. H. W h i t e s i d e s , J. Am. Chem. SOC.
of symmetry s p e c i e s e. Now, t r a n s f e r of a n e l e c t r o n from
/15/
dxy t o one of t h e d e g e n e r a t e e o r b i t a l s (dxz o r d y z ) can be
/17/ R. F. W.
induced by a r o t a t i o n of charge about x o r y , a l s o of sym-
/18/
T. Lee, J. Am. Chem. SOC. 2 , 3909 (1977).
metry s p e c i e s e , a n n i h i l a t i n g t h e s p i n o f t h e x o r y compo-
/19/
S.
n e n t o f t h e t r i p l e t /21/
/20/ a ) E. A. H a l e v i , H e l v e t . Chim. Acta
and c o n v e r t i n g i t t o t h e square-
planar s i n g l e t .
R. G.
H.
The a n a l y s i s p r e s e n t e d above i s i n f u l l a c c o r d w i t h d e t a i l e d t h e o r e t i c a l s t u d i e s / 2 3 , 30/.
Bader, Can. J. Chem.
L i n . J. Chem. Phys.
(1975);
Spin-orbit coupling, i f
s u f f i c i e n t l y s t r o n g , g r e a t l y reduces t h e b a r r i e r c a l c u l a t e d
trans i s o m e r i z a t i o n
zround s t a t e /13,
*
31/,
can pro-
the tetrahedral
D u n i t z , Acta Cryst-
s. 1787 (1978);
W.
Crystallogr..
i s g r a t e f u l t o P r o f e s s o r H.
B.
R.
Gray
S. S h e l d r i c k , R.
Sect. B
B e n d a l l , D. M.
D o d d r e l l , B. W.
2 , 727
A u s t r a l . J. Chem.
Lower-case
Knorr, H. P o l z e r ,
2 , 739 (1979);
dew. Horrocks, R. H.
R.
H.
(1979).
l e t t e r s a r e used t o s p e c i f y t h e symmetry of
Holm i n L. M.
Jackman and F. A. Cotton,
used t o d e s c r i b e t h e symmetry p r o p e r t i e s .
Dynamic
Aca-
/27/ a ) M. E l i a n , R. Hoffmann, Inorg. Chem. l4, 1058 (1975);
b) R.
demic r ' r e s s , New York 1975.
LaMar, E. 0. Sherman, J. Am.
(1970);
Chem. SOC.
compare L. H. P i g n o l e t and W.
Chem. SOC.
J. Am.
5 , 3976
z , 2691
dew. Horrocks,
(1969). f o r an unexplained
W.
dew. Horrocks, R.
z, 1855
/5/
L.
/6/
J. J. McGarvey, J.
Wilson, J. Am.
Chem. SOC.
42,
IV-IX
2,
(1981).
131 (1964).
of Ref. / I S / ,
s t e p r a t h e r than
/3O/
Woodward, R. Hoffmann, The Conservation o f O r b i t a l
-
631
-
a an
e x c i t e d s i n g l e t of t h e p l a n a r
complex o r a n e x c i t e d t r i p l e t of t h e t e t r a h e d r a l one.
Chen.
(1977).
i s simply t h e r e a c t i o n c o o r d i n a t e ,
s o t h e i s o m e r i z a t i o n i s a b l e t o proceed i n a s i n g l e
2531
R. Knorr, F. Ruf, J. Am. Chem. SOC. 101, 5424 (1979).
B.
m, 2595
symmetric n u c l e a r d i s p l a c e m e n t , which appears i n Eqs.
Que, L. H. P i g n o l e t , InorR. Chem. IZ, 156 (1973).
SOC. 2 , 650
R.
Chem. SOC.
L i n , L. E. O r g e l , Mol. Phys.
from h i s : The a n a l o g i n o u r t r e a t m e n t of t h e t o t a l l y
(1970); n o t e f o o t n o t e 49 t h e r e i n .
(1975).
/9/
C.
/29/ O u r a n a l y s i s i s f o r m a l l y e q u i v a l e n t t o Lee's u s e of
H. Holm,
/ 7 / R. Knorr, A. WeiR, H. F o l z e r , E. Rapple, J. Am.
/B/
GI.
L i n ' s Rules I11 and I V , but o u r i n t e r p r e t a t i o n d i f f e r s
L. H. P i g n o l e t ,
Chem. SOC.
J. McKinney, D. L. Thorn, R. Hoffmann, A.
S t o c k i s , J. Am.
/28/
exception.
/4/
l a b e l s are reser-
/ 2 6 / The 3d components of t h e t o t a l m o l e c u l a r o r b i t a l s a r e
Nuclear Mapnetic Resonance S p e c t r o s c o ~ ,p. 317,
/ 3 / G. N.
White,
tions.
magnetic Molecules, Academic P r e s s , N e w York and Lon-
/2/
H.
ved f o r t h e r e p r e s e n t a t i o n s of s t a t e s and configura-
Holm, NMR of Para-
don 1973.
Acts
P. C. Healey, M.
S k e l t o n , A.
o r b i t a l s and c o o r d i n a t e s ; upper-case
LaMar, W.
283
L. L. L o h r , J. Am. Chem. SOC. 100, 1093 (1978).
/24/ See, e.g.:
/25/
N.
1
2. 703 (1979).
b) S e c t . A
/23/
f o r i n t r o d u c i n g h i m t o t h i s problem.
/I/
G.
40,
- 632 -
complex a s a n i n t e r m e d i a t e .
One of us (E. A. H.)
(1975);
2, 593 (1976).
Burgi, J. D.
H.-B.
a ) Sect. B
-
ceed w i t h two s u c c e s s i v e s p i n - f l i p s
2 , 2136
H a l e v i , Theor. Chim. Acta
H a l e v i , C. T r i n d l e , I s r a e l J. Chem. I
&
,
alloe;r.,
of n i c k e l ( I 1 ) complexes, which i s "for-
bidden" i n t h e c l o s e d - s h e l l
(1966).
(1977).
&-
that the
(1962).
c ) E. A. H a l e v i , Angew. Chem. B8, 664 (1976);
/22/ P. Murray-Rust,
A s a f i n a l p o i n t , i t s h o u l d be noted /15/
- 630
E. A.
3 , 1164
s,3759
Angew. Chem. I n t . E d i t . Engl.
/21/
f o r i s o m e r i z a t i o n and c o n v e r t s it f r o m a h i g h l y i n e f f i c i e n t
p r o c e s s t o a T e l a t i v e l y f a c i l e one.
Chem. SOC. p1, 1252 (1969).
P e a r s o n , J. Am.
b) J. K a t r i e l , E. A.
(1969).
L.
L. Lohr, E. K. Grimmelmann, J. Am. Chem. SOC. 100,
1100
(1978).
/Jl/
According t o OCAMS, t h e c i s - t r a n s
- 633 -
isomerization is
"allowed" f o r m l i y b y a b,,-pertdrbation,
whici uould
ander aktiviert werden. Die Alkohole
i n d u c e c3rrespondence b e t w e e n dxz and dxy. This can
9,
die u.a. als Ausgangsmateria-
lien fur neuartige kreuzkonjugierte Triene benotigt wurden (siehe an-
only oe a h v h - e n e r f y f vib-ation, w h i c h would raise tie
schlieBende Mitteilung /2/), lassen sich bequem herstellen, wenn zu-
a c t i v a t i o n e n e r - y , a n d t h u s i n h i b i t t h e isonerizazion
nachst zwei Rquivalente Allylmagnesiumbromid
of t h e tdo cl7se&-s:.ell
s;,.ecies alon- t n e -::iist patn-
(2)
/3/ mit Propargyl-
chlorid (f) 141 umgesetzt werden. Dabei bildet sich in nahezu quanti-
way.
tativer Ausbeute 1-Hexen-5-inyl-magnesiumbromid
(31, wie dessen Hydro-
lyse (g=H20) zum Stammkohlenwasserstoff p zeigt. Als Vorstufe von
Received March 1 2 , 1 9 8 2
/Z
wird entweder die 112 entsprechende Propargylgrignard-Verbindung
39 S /
5
oder
1-Hexen-5-in ('6) durchlaufen, je nachdem ob die Umgrignardisierung oder
die C-C-Verknupfung zwischen 3.und
valent
2
4.rascher verlauft. Das zweite Rqui-
dient dann zur Erzeugung von
onylverbindungen
g
7,
das sich durch Zugabe von Carb-
zum gewunschten Produkt
2 abfangen
laBt 151.
Einen ersten Eindruck von der Anwendungsbreite des Verfahrens vermitteln
die in der Tabelle zusammengefaBten Reaktionen, die bis auf den Fall der
Umsetzung von I_ mit Aceton in ihren Ausbeuten noch nicht optirniert
wurden. Wie die letzten vier Eintragungen zeigen, konnen auch andere
7
elektrophile Reagenzien als Aldehyde und Ketone mit
verknupft werden.
Eine weitere praparativ nutzliche Ausdehnung erfahrt die Methode durch
Variation des reaktionsauslosenden Grignardreagenz
2 und der zentralen
Kupplungskomponente f: Beispielsweise liefert die Verknupfung von Ethylmagnesiumbromid, Propargylchlorid und Acetaldehyd 3-Heptin-2-01 ( 2 2 % )
151 bzw. Allylmagnesiumbromid, Propiolaldehyd und Acetaldehyd 7-Octen-
3-in-2,5-diol (36%) / 5 l .
634
-
I
I
Dieses Manuskript ist
zu zitieren als
Angew. Chem. Suppl.
1982,635-639
-
-
-
Formelschema und Tabelle:
I
This manuscript is
to be cited as
Angew. Chem. Suppl.
1982,635 -639
636
I
0 Verlag Chemie G m b H , D-6940 Weinheim,1982
H2C=CH-CH2CH2C~C-MgBr
0721 -422718210404-0640s02.5010
I
9
~
Eintopfverfahren zur Synthese von 1-A1 ken-5-in-Derivaten i l l
,+S+SHanno Priebe und Henning Hopf *
In 3-Stellung metallierte Propargylhalogenide 1 sind dem Zwitterion
=
zum Aufbau komplizierterer Kohlenstoffgeruste anbietet, da sie sowohl
mit elektro- als auch nukleophilen Partnern verknupfbar sein sollte:
Wie die im folgenden beschriebene Eintopfreaktion zur Darstellung ver-
9
(E=C(OH)R1R2; R 1 R 2 = H , Alkyl, Alkenyl,
Aryl etc.) zeigt, ist das auch der Fall, wenngleich hierbei die elektronenreichen bzw. -armen Zentren in
_____~
~
1 nicht gleichzeitig, sondern nachein-
~
Dip1.-Chem. H. Priebe, Pro?. Dr. H. Hopf
(g)
z
aquivalent, einer Spezies, die sich als funktionalisierter C3-Baustein
schiedener Alkeninole vom Typ
E-X
1
- Mg8rX
H2C=CH-CH2CH2-CX-E
( 9 = R-E)
R-H
R-CH20H
18
CH3CH0
R-CH(OH)CH3
50
C2H5CH0
R-CH(OH)C2H5
32
(CH?)2CH-CH0
R-CH(OH)-CH(CH3)2
45
93
HzC=CH-CHO
R-CH( OH) -CH=CH2
31
(CH3)$=0
R-C(OH) (CH3)2
83
(CH2)4C=0
R-C( OH) ( CH2I4
35
H2C=CH-CO-CH3
R-C(OH)CH3(CH=CH2)
22
(CH~)~N-CHO
R-CHO
15
(CH3C0),O
R-CO-CH3
17
CO2
(CH2)20
R-C02H
63
R-CH2CHz-0H
13
Technische Universitat Braunschweig
SchleinitzstraBe, 0-3300 Braunschweig
635
-
% /5/
H20
CH20
Institut fur Organische Chemie
-
Ausbeute,
- 637
-
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