A new PEPPSI type N-heterocyclic carbene palladium(II) complex and its efficiency as a catalyst for Mizoroki-Heck cross-coupling reactions in water

Article abstract of DOI:10.1007/s12039-020-1754-y

Abstract: A new air and moisture stable PEPPSI (PEPPSI: pyridine-enhanced pre-catalyst preparation, stabilisation, and initiation) themed palladium N-heterocyclic carbene (NHC) complex [Pd(L)Br₂(Py)] (1) [L: 2-flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazolline-2-ylidene] was synthesized and characterized. The structure of complex 1 was determined by X-ray single-crystal analysis. The palladium center in 1 adopted a square planar geometry with carbene and pyridine ligands occupying the mutual trans position. The complex 1 was employed to catalyze the Mizoroki-Heck cross-coupling reactions of aryl bromides/iodides with styrene in water. To the best of our knowledge, this is the first report where a Pd-PEPPSI catalyst was successfully employed in aqueous-phase Mizoroki-Heck reaction. Good to excellent yields of cross-coupling products were obtained with a range of representative aryl bromides/iodides under relatively mild conditions (100 °C, 1 mol% of 1). Graphic abstract: A new palladium PEPPSI complex was synthesized, characterized and evaluated as catalyst for the Mizoroki-Heck reaction in aqueous medium. Both electron-donating and electron-withdrawing aryl halides (bromides and iodides) reacted with styrene to give corresponding coupling products in moderate to excellent yields.[Figure not available: see fulltext.].

Full text of DOI:10.1007/s12039-020-1754-y

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REGULAR ARTICLE
A new PEPPSI type N-heterocyclic carbene palladium(II) complex
and its efficiency as a catalyst for Mizoroki-Heck cross-coupling
reactions in water
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Abstract. A n e w a i r a n d m o i s t u r e s t a b l e P E P P SI ( P E P P S I : p y r id in e - e n h a n c e d p r e - c a t a l y s t p r e p a ra t i o n,
s t ab i l i s a t i o n , a n d i n i t i a t i o n ) t h e m e d p a l la d i u m N - h e t e r o c y c l i c c a r b e n e ( N H C ) c o m p le x [ P d ( L ) B r ( P y ) ] ( 1) [ L:
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s t r u c t u r e o f c o m p l e x 1 w a s d e t e r m i n e d b y X - r a y s i n g l e - c r y s t a l a n a ly s i s . T h e p a l l a d i u m c e n t e r i n 1 a d op t ed a
s q u ar e p l a n a r g e o m e t r y w i t h c a rb e n e a n d p y r i d in e l ig a n d s o c c u p y i n g t h e m u t u a l trans p o s i t i o n . T h e c o m p le x
1 w a s e m p l o y e d t o c a t a l y z e t h e M iz o r o k i - H e c k c r o s s - c o u p l in g r e a c t io n s o f a r y l b r o m id e s / i o d i d es w i t h
s t y r e n e i n w a t e r. T o t h e b e s t o f o u r k n o w l e d g e , t h i s i s t h e fi r s t r e p o r t w h e r e a P d - P E P P S I c a t a l y s t w a s
s u cc e s s f u l l y e m p l o y e d i n a q u e o u s - p h a s e M i z o r o k i - H e c k r e a c ti o n . G o o d t o e x c e l l e n t y i e l d s o f c r o s s - c o up l i ng
p r o d u c t s w e r e o b t a i n e d w i t h a r a n g e o f r e p r e s e n t a t i v e a r y l b r o m i d e s / io d i d e s u n d e r r e l a t i v e l y m i ld c o nd i t io n s
( 1 0 0 °C , 1 m o l % o f 1) .
Keywords. N -h e t e ro c y c l i c c a rb e n e ; P a l la d i u m ; P E P P SI ; M i z o r o k i - H e c k r e a c ti o n ; a q u e o u s m e d i a .
1. Introduction
d u e t o t h ei r s t ro n g r- d o n a t i n g a n d p o o r p- a c ce p t i n g
p r o p er t i es , t h ey c an p r o d u c e m an y s t ab l e c o m p l e x e s
c o m p a re d t o t h e a n a l o g o u s p h o s p h i n e - b a s e d s y s t e m s .
5
N - he t er oc yc l i c c a r b e n e s ( N H C s ) a r e a m on g t h e m o s t
i n t r i g u i n g c l a s s e s o f l ig a n ds t ha t h a ve g e n e r at e d
n u m er o u s b r e a k t h r ou g h s i n t h e fi e ld o f o r g a n o me t a l -
I n t h e p a s t f e w y e a rs , P d - N H C s y s t e ms h a v e b e e n
i n cr e a s i n g l y u s e d a s c at al y s t s f o r v a r i o u s t y p e s o f
c r o s s - c o u p l i n g r e ac t i o n s . S i n c e t h e fi rs t r ep o r t o f t h e
u t i l i za t i o n o f P d - N H C s y s t e m i n M i z o r o ki - He ck
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g r e s s t h at h a s b e e n m ad e i n t h i s fi el d , t o d a t e , o n l y a
f e w c at a l y t i c s y s t e ms a re e ff e c t i v e t o c ar r y o u t t h e
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e r t y , n o n - t o xi c b e h a v i o u r , a i r a n d m o i s t u re
s t ab l e p r o p e r t ie s , a n d t u n e a b l e c a t a l yt ic a c t iv i t y via
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o r g a n i c s y n t h e s i s . I n t h i s p r o s p e ct , t h e d e v e l o p m e n t
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Electronic supplementary material: The online version of this article (https://doi.org/10.1007/s12039-020-1754-y) contains
supplementary material, which is available to authorized users.

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J. Chem. Sci. ( 2 0 2 0 ) 1 3 2 : 5 1
r e a c t i o n i n w a t e r i s o f t re m e n d o u s s i g ni fi ca n c e . 2. Experimental
A m o n g v a r i o u s N H C s y s t e m s , t he a i r -s ta b l e a n d u s e r -
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c at a l y s t p r e p a r a ti o n , s t a bi li s a t io n, a n d i n i t i a t i o n )
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a t m o s p h e r e u n l e s s o t h e r w i s e s t a t e d . T h e i m id a z o l e p re c u r-
s o r s ( 4 - m e t h o x y p h e n y l) - 1 H - i m id a z o l e a n d P d C l w e re
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o r g a n i c r e a c t i o n s . T h e N H C l ig a n d , b e c a us e o f i t s
s t r o n g trans d i r e c ti n g p ro p e rt y , i s e x pe c t e d t o c r ea t e a
v a c a n t s i t e f o r s u b s t ra te b in di n g b y e a s i l y r e l e a s i n g
t h e l a b i l e p y r i d i n e l ig a n d t ra n s t o N H C a n d t h u s
w o u l d e n h a n c e t h e c a t a l y t i c a c t iv i ti e s . I n f a c t , t h er e
e x i s t s e v e r a l r e c e n t r e p o r ts o n t h e u ti l it y o f P E PP S I -
p u r c h a s e d f r o m T C I a n d S i g m a - A l d r i c h , r e s p e c t i v e ly . A l l
s o l v e n t s , s u b s t r a t e s f o r c a t a l y s i s a n d o t h e r c h e m ic a ls w e re
p u r c h a s e d f r o m v a r io u s c o m m e r c i a l fi r m s l ik e T C I , A c ro s
O r g a n i c s , a n d M e r c k . T h e N M R s p e c tr u m f o r t h e i m i d a-
z o l i u m s a l t L w a s r e c o r d e d i n C D O D , w h il e t h e c om p le x
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i n t e r n a l s t a n d a r d a n d o p e r a t in g o n a B r u k e r A v a nc e 4 00
M H z N M R s p e c tr o m e t e r . H i g h - r e s o l u t io n m a s s s p e ct r a
w e r e r e c o r d e d w i t h a n A g il e n t 6 5 5 0 i F u n n e l Q - TO F M S
s y s t e m . T h e G C M S s p e c t r a o f t h e c a t a l y t i c p r o d u c t s w e re
p e r f o r m e d i n a n A g il e n t G C M o d e l 7 8 2 0 A w i t h a m a s s
d e t e c t o r m o d e l 5 9 7 5 s e r i e s .
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a q u e o u s p h a s e c r o s s - c o u p l ing r e a c t io n l ik e S u z u k i -
M i y a u r a r e a c t i o n . T o c i t e a n e x a m p l e , r e c en t l y
C h o u d h u r y et al., h a ve r e p o r te d a n e f fi c i e n t c o - o r d i -
n a t i o n p o l ym e r a n c h o r e d P d -N H C s y s t e m a n d t h ei r
a p p l i c at i o n a s a p ro m is in g c a t a l y s t i n a q ue ou s p h as e
2 . 2 Procedure for preparation of 3-(2-
flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazolium
bromide (L)
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P E P P S I- Pd - N H C c o m p le x e s a r e e m p l oy e d i n M i z o r -
( 4 - m e t h o x y p h e n y l ) - 1 H - i m id a z o l e ( 1 7 4 m g , 1 m m o l ) a nd
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r o n m en ta l l y u n f a v o u ra b l e r e a c t io n m e di a l ik e d i o x a n e
a t 8 0 °C f o r 4 8 h . T h e r e a c t io n m i x t u r e w a s a l l o w e d t o c om e
t o r o o m t e m p e r a t u r e a n d d i e t h y l e t h e r w a s a d d e d t o o bt a i n a
p r e c i p i t a t e . T h e s o l u t io n w a s fi l te r e d a n d t h e s o l i d r es i du e
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p e r t a i n i n g t o t h e u ti l it y o f P d -P E P P S I- N H C c o m -
p l e x e s i n t h e M i z o r o k i - H e c k r e a c t io n i n w a t e r ,
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Figure 1. P E PP S I -P d - N H C p r e c a t a l y s t s f o r M i z o r o k i - H e c k r e a c t io n .

J. Chem. Sci. ( 2 0 2 0 ) 1 3 2 : 5 1
P a g e 3 o f 1 0 5 1
5 6 . 3 4 , 4 9 . 6 3 . H R - M S : [ M - B r ] ? = 2 8 3 . 1 6 , c a l c u l a t e d : 0 . 0 3 4 3 ; w R 2 : 0 . 0 5 8 0 ; R e fl e c t i o n s c o l l e c t e d : 6 9 8 2 5 ; U n i qu e
2 8 3 . 1 2 .
r e fl e c ti o n s : 4 8 0 7 ; O b s e r v e d r e fl e c t io n s : 3 4 7 2 .
C o m p l e x 1a ( C C D C n o : 1 8 6 3 5 4 3 ) , E m p i r i c a l F o r m u l a:
C H B r N P d ; M W ( g /m o l ) : 4 2 4 .4 2 ; C r y s t a l s i z e :
0 . 2 7 x 0 .2 1 x 0 . 1 1 ; C o l o u r : Y e l l o w ; C r y s t a l s y s t e m : T r i cl i ni c ;
1
0
1
0
2 2
2 . 3 Procedure for the preparation of PEPPSI-Pd-
NHC (1) complex
˚
S p a c e g r o u p : P1; C e l l l e n g t h ( i n A ) : a, 5 . 6 5 6 ( 3) ; b:
7 . 1 2 5 ( 3 ) ; c: 7 . 7 8 4 ( 4 ) ; C e l l a n g l e s ( i n 8) , a: 7 9 . 9 5 8 ( 4 ); b:
8 8 . 6 8 1 ( 4 ) ; c: 8 8 . 6 8 1 ( 4 ) ; C e l l v o l u m e , 3 0 7 . 3 ( 3 ) ; C e l l d en s i t y
A 5 0 m L fl a s k e q u i p p e d w i t h a m a g n e t i c s t i r b a r w a s
c h a r g ed w i t h i m i d a z o l i u m s a l t L ( 2 1 8 m g , 0 . 6 m m o l ) ,
P d C l ( 8 9 m g , 0 . 5 m m o l ) , K C O ( 2 0 7 m g , 1 . 5 m m o l ) ,
3
1
[ g /c m ] : 2 . 2 9 3 ; T ( K ) : 1 0 0 K ; l ( m m - ) : 4 . 3 0 8 ; G o F : 1 .1 4 5 ;
R 1 : 0 . 0 7 6 ; w R 2 : 0 . 2 3 6 1 ; R e fl e c t i o n s c o l l e c t e d : 9 34 4;
U n iq u e r e fl e c ti o n s : 1 5 9 0 ; O b s e r v e d r e fl e c ti o n s: 1 4 6 4.
2
2
3
e x c e s s K B r , p y r i d i n e ( 5 m L ) . T h e m i x t u re w a s a l l o w e d t o
s ti r a t 8 0 °C f o r 4 8 h a n d t h e n c o o l e d t o r o o m t e m p e r a tu r e
a n d t h e s o l v e nt w a s r e m o v e d u n d e r v a c u u m . T h e r e s i d u e
w a s d i s so lv e d i n d i c h l o r o m e t h a n e ( DC M ) a n d p u r i fi e d b y
c o l u m n c hr o m a to g r a p h y , e l u t i n g w i t h D C M / h e x a n e ( 7 :3 ) .
C o m pl e x es 1a a n d 1 w e r e r e c o v e re d f ro m t h e fi rs t a n d s e c o n d
2
.
5
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A r o u n d - b o t t o m e d fl a s k ( 5 0 m L ) e q u ip p e d w i t h a c o n de n s e r
a n d a m a g n e t i c s t ir r i n g b a r w a s c h a r g e d w i t h a r y l h al i d e
( 1 m m o l ) , s t y r e n e ( 1 .5 m m o l ) , K C O ( 3 m m o l ) a nd 1
f ra c t io n o f t h e s o l v e n t r e s p e c t i v e l y . Complex 1: Y i e l d 2 6 5
1
2
3
m g , ( 7 0 % ) ; y e ll o w p o w d e r ; H N M R ( C D C l , 4 0 0 M H z , d,
3
( 1 m o l % ) i n w a t e r ( 3 m L ) w e r e a l l o w e d t o s t ir a t 1 0 0 °C i n
a i r . T h e p r o g r e s s o f t h e r e a c t io n w a s m o n i t o r e d b y T LC
( h e x a n e / e t h y l a c e t a t e , 4 : 1 ) . A f t e r c o m p l e t i o n o f t he r ea c-
t io n , t h e r e a c ti o n m i x t u r e w a s c o o le d t o r o o m t e m p er at u r e .
E t h y l a c e t a t e ( 1 5 m L ) w a s a d d e d t o t h e r e a c t io n m i xt u r e.
T h e o r g a n i c l a y e r w a s w a s h e d w i t h w a t e r ( 3 x 1 0 m L) a nd
p p m ) 8 . 8 7 ( d , J = 8 H z , 2 H , p y ) 7 . 9 0 ( t , J = 7 . 6 H z , 2 H , P y ) ,
7 . 8 4 ( t , J = 9 . 2 H z , 1 H , p y ) , 7 . 7 1 -7 . 6 7 ( m , 1 H , a r o m a t i c ) ,
7 . 4 0 - 7 . 3 5 ( m , 1 H , a r o m a t i c ) , 7 . 2 7 -7 . 2 4 ( m , 2 H , a r o m a t i c ) ,
7 . 2 0 - 7 . 1 5 ( m , 2 H , a r o m a t i c ) , 7 . 0 7 -7 . 0 3 ( m , 2 H , a r o m a t i c ) ,
7 . 1 1 ( d , J = 2 . 4 H z , 1 H , C H = C H i m i d a z o l e ), 6 . 9 7 ( d , J = 1 . 6
H z , 1 H , C H = C H i m i d a z o l e ) , 5 . 9 4 ( s , 2 H , b e n z y l C H ) , 3 . 6 8
2
d r ie d o v e r a n h y d r o u s M g S O a n d t h e r e a c ti o n m i x t u r e w a s
4
1
3
( s, 3 H , O C H ) , C ( C D C l , 1 0 0 M Hz , d, p p m ) 1 6 2 . 1 , 1 5 9 .7 ,
3
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C
-
M
S
.
3
1 5 2 . 5 , 1 4 9 . 8 , 1 4 9 . 5 , 1 3 7 . 7 , 1 3 2 . 5 , 1 3 2 . 2 ( d , J = 3 . 2 H z ) ,
C , F
3
1 3 0 . 6 ( d , J = 8 . 2 H z ), 1 2 4 . 7 ( d , J = 3 . 6 H z ) , 1 2 4 .4 ,
4
C
,
F
C , F
2
1 2 3 . 9 , 1 2 2 . 2 ( d , J = 1 4 . 1 H z ) , 1 2 1 . 8 , 1 1 5 . 5 ( d , J = 2 1 . 2
2
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6
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H z ) , 1 1 4 . 2 , 5 5 . 4 , 4 8 . 3 ( d , J = 4 . 2 H z ); H R M S : [ M - 2 B r -
C , F
?
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H
]
=
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0
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7
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2
.
T h e s a m p l e w a s p r e p a r e d b y t h e d o p in g o f a n e th a no l
s o l u t i o n o f p a l l a d i u m b l a c k o n t h e c o p p e r g r id c o a t e d w i t h
c a r b o n . T r a n s m i s s io n e l e c t r o n m i c r o g r a p h s w e r e r ec or d ed
o n a J E O L J E M - 2 1 0 0 p l u s e l e c t r o n m i c r o s c o p e .
2
.
4
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S in g l e c r y s t al X - ra y d i f fr a c t i o n : S i n g l e c r y s t a l X - r a y
d i ff r a ct i o n s w e r e c o l l e c t e d o n a B r u k e r S M A R T A P E X - I I
3. Results and Discussion
˚
C
C
D
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1
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3 . 1 Synthesis and characterisation of ligand
and complex
t io n . B r u k e r S A I N T s o f t w a r e h a s b e e n e m p l o y e d f o r
r e d u c in g t h e d a ta a n d S AD A B S f o r c o rr e c t i n g t h e i n t e n s i -
1
7
t ie s o f a b so r pt i o n . A l l c o -c ry s t a l s t r u c t u re s w e re s o l v e d
a n d r e fi n e d u s i ng S H E L X L w i t h a n i s o t r o p i c d i s p l a c e m e n t
p a r am e t er s f o r n o n - H a t o m s . I n a l l c r y s t a l s t r u c t u r e s ,
H - a t o m s a r e l o ca t e d e x p e ri m e n t a l l y , w h e r e a s C – H a t o m s
w e r e fi x e d g e om e t r i c a l l y u s i n g t h e H FI X c o m m a n d i n
T h e N H C s a l t ( 2 - flu r o b e n z y l )- 1 -( 4- me t h o x y p h e n y l ) -
1 H - i m i d az o l i u m b r o m i d e (L) w a s p r e p a r ed b y t h e
a r y l a t i o n o f ( 4 - m et h o x y p h e n y l )- 1 H - i m i d a z o l e w i t h
2 - fl u o r o b e n z y l b r o m i d e b y f o l l o w i n g a m et h o d s i m i l a r
1
8
2
1
S HE L X - T . T h e fi g u re s a n d p a c k i n g d i a g ra m s a r e m a d e
u s in g M er cu r y 3 . 9 v e rs i o n . N o m i s s e d s y m m e tr y w a s
1 9 , 2 0
o b s er v e d i n t h e fi n a l c h e c k o f C I F fi l e u s i n g P L AT O N .
t
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1
1
3
t h e L w a s a s s i g n e d b a s e d o n N M R ( H a n d C ) a n d
m as s s p e c t r a l d a t a . T h e E S I -M S s p e c t r u m o f L s h o ws
t h e b a s e p e a k a t m/z = 2 8 3 . 1 c o r re s p o n d s t o [ M - Br ] ?
Crystallographic parameters:
1
i o n s . I n t h e H N M R s p e c t r u m , t h e i m i d az o l i u m p r o -
t o n o f L a p p e a re d a t 9 . 6 0 p p m , a n d t h e v a l u e i s c o n -
C o m p l e x 1 ( C C D C n o : 1 8 6 0 3 9 1 ) , E m p i r i c a l F o r m u l a :
C H B r F N O P d; M W ( g / mo l ) : 6 2 6 . 6 4 ; C r y st a l s i z e : 0 . 2 5
x 0 . 1 5 x 0 . 1 1 ; C o l o u r : P a l e y e l l o w ; C r y s t a l s y s t e m : M o n -
2
2
1
9
2
3
2
2
1 3
s i s t e n t w i t h t h e l i t e r at u r e d a t a . T h e C N M R s i g n a l
o f t h e c ar b e n e ( N CN ) o f L d i s p l a y e d a t 1 3 6 . 6 6 p p m .
T h e P E PP S I - Pd - N H C c o m p l e x 1 w a s s y n t h e s i z e d b y
˚
o c l i n ic ; S p a c e g r o u p : P2 / c; C e l l l e n g t h ( i n A ) : a,
1
1
6
.
2
3
0
(
3
)
;
b
:
8
.
5
3
7
0
(
1
4
)
;
c
:
3
3
.
3
1
7
(
5
)
;
C
e
l
l
a
n
g
l
e
s
,
a
:
9
0
;
8 a
f o l l o w i n g O r g a n s ’ p r o c e d u r e b y t r e a t i n g P d C l w i t h
c o r re s p o n d i n g c ar b en e p r e c u r s o r ( L) i n p y ri d i n e i n t h e
3
b: 9 0 ; c: 9 0 ; C el l v o l u m e , 4 5 9 9 . 2 ( 1 3 ) ; C e l l d e n s i t y [ g /c m ] :
2
-
1
1
.
8
1
1
;
T
(
K
)
:
1
0
0
K
;
l
(
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:
4
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;
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F
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J. Chem. Sci. ( 2 0 2 0 ) 1 3 2 : 5 1
Scheme 1. S y n t h e s i s o f P E P P SI - P d - N H C c o m p le x 1.
Figure 2. M o l e c u l a r s t r u c t u re o f 1a.
p r e s e n c e o f K C O a n d e x c e s s o f K B r ( S c h e m e 1) .
2
3
A f t e r t h o r o u g h p u r ifi c a ti on b y c o l um n c h ro m a t o g ra -
p h y , t h e c o m p l e x 1 w a s i s o la t e d i n 7 0 % y i e ld s a n d i t i s
a i r a n d m oi s t u r e s t a b l e a n d c a n b e s t o re d f o r m o r e t h an
s i x m o nt h s w i t h o u t a n y n o t ic e a bl e d e c o m p o s i ti o n . T h e
c o m p l e x i s s o l u b le i n p o l a r o rg a n ic s o l ve n t s l i k e
c h l o r o f o r m , d i ch l o r o m e t h a n e , a c e t o n i tr i le , a n d a ce -
t o n e . A l on g s i d e t h e c o m p le x 1, a s m a l l a m o u n t o f
k n o w n b i s - p y r i d i n e c o m p le x, trans- [P d ( B r) ( P y ) ] ( Py
= p y r i di n e ; 1a) w a s a l s o i s o la te d a s a s i d e p r o d u c t .
S i n c e t h e m o l e c u la r s t r uc t u r e o f c o m p le x 1a i s n o t
r e p o r t e d , w e h a v e d e t e r m i n e d i ts s t r u c tu re b y X - r ay
s i n g l e - c r y s t al a n a l y s i s a n d t he m o le c u la r s t r u ct u r e i s
d i s p l a y ed i n F i g u r e 2 . T h e X - ra y q u a l i t y c r y s t a l s o f 1a
w e r e g r o w n t h r o u g h s l o w d if fu s i o n o f h e xa ne i n t o a
c o n c e n t r a t e d d i c h l o r o m e t h a n e s o l u t i o n . T h e c o m p l e x
a d o p t s a r e g u l a r s q u a r e p l a na r g e om e t ry i n w h i ch t h e
P d c e n t e r i s p r e d i c t a b ly s u rr o un d e d b y t w o p y r i d i n e
a n d t w o b r o m i n e l ig a n ds i n m u t u a l trans p o s i t i o n s .
T h e m ol e c ul a r d i m e n s i o n s o f t he c o m p le x 1a a re
Figure 3. M o l e c u la r s t r u c t u r e o f 1.
˚
( 2 . 0 1 8 ( 8 ) A) o r d i ch l o r o c o m p l e x ( 2 . 0 2 4 ( 6 ) A ) . T h e
˚
i d en t i t y o f t h e P E P PS I -P d - N H C c o m p l e x 1 w a s c o n -
1
2
2
1 3
fi rm e d b y H , C N M R a n d m as s s p e c t r o m e t r y . T h e
f o r m at i o n o f t h e P d - C b o n d i n t h e c o m p l ex w as
e v i d en t f r o m t h e d i s a p p e ar a n c e o f t h e i m i d a z o l i u m
c ar b en e
p r o t o n ( N C HN ) s i g n a l . O t h er c h a ra c t e r i s t i c p ea k s o f
1
t h e l i g a n d p r e c u r s o r , L w e re o b s er v ed i n t h e H N MR
1 3
s p e c t r u m o f t h e c o m p l e x . I n t h e C N M R , t h e p a l l a -
d i u m c ar b e n e c ar b o n a p p e a re d a t d 1 5 1 p p m f o r t h e
c o m p l e x 1, a n d t h e v a l u e i s s i mi l a r t o t h e o t h e r
2 5
r e p o r t e d P d - N H C c o m p l e x e s . C o m p ar e d t o t h e f r e e
i m i d az o l i u m s a l t t h i s v a l u e i s s h i f t e d d o w n fie l d i n d i -
c at i n g c o m p l e x a t i o n . T h e m as s s p e c t r u m o f t h e c o m -
p l ex 1 e x h i b i t s a l o w i n t e n s e p e a k a t m/z, 3 8 7 . 0 2 f o r
[ M - 2 B r -P y?H ?]?. T h e i s o t o p i c p a t t er n s o f a l l t h e m/z
p e a k s o f t h e c o m p l e x 1 m at ch ed w i t h t h e e x p e c t e d
p a t t er n s . T h e m o l e c u l a r s t ru ct u r e o f t h e c o m p l ex 1 i s
d e t e r mi n e d b y X - r ay s i n g l e- c ry s t a l a n a l y s i s a n d t h e
m o l e c u l a r s t ru ct u r e o f 1 i s d i s p l a y e d i n F i g u re 3. T h e
c ry s t a l s s u i t a b l e f o r X - r ay a n a l y s i s w e r e g r o wn b y
m o r e o r l e s s s i m i la r t o t h e a n a l o g u e s d i i o d o -[ P d I
2
2 3
( P y ) ] o r d i ch l o ro c o m p le x trans- [P d C l ( P y) ] . A s
2 4
2
2
2
e x p e c t e d , t h e P d - X b o n d d is ta nc e s i n t he c o m p l e x e s
trans- [ P d X ( P y ) ] f ol l ow t he t re n d : P d -I ( 2 . 6 2 3 ( 1 5 )
2
2
˚
˚
˚
A )[P d - B r ( 2 . 4 11 (2 ) A )[P d -C l ( 2 . 2 97 (1 ) A ) . T h e P d -
˚
N b o nd l e n g t h ( 2 . 0 5 3( 9) A ) i n t he c o m p le x 1a i s
s l i g h t l y l o n ge r t h a n t h a t o f t he a n a l o g o us d i i o d o

J. Chem. Sci. ( 2 0 2 0 ) 1 3 2 : 5 1
P a g e 5 o f 1 0 5 1
s l o w d i f f u s i o n o f h e x a n e i nt o a c o nc e n t ra t e d a ce t o n e a n d c o m p l e x 1 ( 1 . 0 m o l % ) a t a t e m p e ra t u r e m e n t i o n e d
s o l u t i o n o f t h e c o m p le x 1 a t r o o m t e m p e r a t u r e. T h e i n T a b l e 1 f o r 2 4 h . T o o u r d i s a p p o i n t m en t , n o d e s i r e d
c o mp l ex c r y s t al li z e s i n t h e m o n o c l i n i c s p a c e g r o u p p r o d u ct w a s o b t a i n e d ( T a b l e 1 , e n t r i es 1 - 4 ) . H o w e v e r,
P2 /c w i t h t w o m o le c u le s i n t h e a s y m m e t ri c u n i t ( Z = t h er e a r e l i t e r at u r e p r e c ed e n t s a v a i l a b l e t h a t t h e
1
4 ) . T h e c r y s t al d a t a p a ra m e t e r i s s u m m a r i z e d i n a d d i t i o n s o f t e t r a - n - b u t y l a mm o n i u m b r o m i d e
T a b l e S 1 ( S u p p l e m e n t a r y I nf or m a ti o n ) . M o l e c u l es a r e ( T B A B) , a s a n a d d i t i v e, e f fe c t i v el y i m p r o v e t h e
2 7
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H ÁÁÁp a n d pÁÁÁp ( F i g ur e S 1 3 , S u p p l e m e n t a r y I n fo rm a - u s t o e x a mi n e t h e c at a l y t i c p e r f o r ma n c e o f t h e c o m -
t i o n ) t o c o mp l et e t he t hr e e p a c k in g s . S y m m e tr y i n d e - p l ex 1 i n p r e s e n c e o f T B A B a n d w e w e re p l e a s ed t o
p e n d e n t m o l e c u l e r u n s a l o ng [ 0 1 0] a x i s via pÁÁÁp fi n d t h at a d d i t i o n o f T B A B ( 1 . 5 e q u i v a l e n t s ) i n t h e
i n t e r a c t i o ns . T w o s u c h m o l e c u l a r t a p e s a r e h e l d m o d e l s y s t e m s i g n i fic a n t l y i m p r o v e d t h e c o n v e rs i o n
t o g e t h e r b y w e a k C - H ÁÁÁO a n d C – HÁÁÁp i n t e r a ct i o n s o f p r o d u ct t o 8 4 % f o r t h e c o m p l e x 1 ( 1 m o l % ) i n
( F i g u r e 4) . T h e C - H …F i nt e r a c ti o n p l a ys a n i m p o r t an t w a t e r u n d e r a i r i n p r e s e n c e o f K C O b a s e ( 2 e q u i v -
2
3
r o l e t o c o m p l e t e t h e m o le c u la r p a c k in g . T h e P d m et al a l e n t s ) ( T a b l e 1, e n t r y 8 ) . T h e c o n v er s i o n o f t h e
i n t h e c o m p l e x 1 a d op t s a d i s to rt e d s q ua re p l an ar p r o d u ct c o u l d b e f u r t h er i n cr e a s ed t o 9 5 % b y s i m p l y
e n v i r o nm e n t w i t h c a rb e n e a n d p y r id in e o c c u p y i n g i n cr e a s i n g t h e K C O c o n c e n t r a t i o n f r o m 2 t o 3
2
3
m u t u a l trans p o s i t i o n ( F i g u re 3 ) . T h e P d - C
˚
e q u i v a l e n t s ( T a b l e 1 ; e n t r y 9 ) . A s d e m o n s t r a t e d i n
( 1 . 9 7 3( 7) A ) a n d P d -N ( 2 . 1 06 (6 ) A ) b o n d d i s t a n c e s T a b l e 1 , o n l y T H F ( E n t ry 7 ) c an s h o w c o m p a r a b l e
c ar b en e
˚
p y
i n 1 a r e c o m p a r a b le t o t ho s e r e p o rt e d f o r o t h e r r e s u l t s w i t h H O , w h i l e m u c h l o w er c o n v er s i o n s a r e
2
1 1 a ,2 6
P E P P S I - P d- N H C c o m p le x e s .
I t i s i n t e r e s t i n g t o o b t a i n e d w i t h s o l v e n t s l i k e D M F a n d t o l u e n e ( e n t r i e s
n o t e t h a t P d-N d i s t a n c e i n t he c o m p le x 1 i s m u c h 5 & 6 ) . I t i s i m p o r t an t t o n o t e t h at i n t h e a b s e n c e o f
l o n g e r t h a n t h e P d -N d i s ta n c e i n t he c o m p l ex 1a c at a l y s t , n o c o n v er s i o n w a s o b s er v e d ( T a b l e 1 ; e n t r y
˚
( 2 . 0 53 ( 9 ) A ) w h i c h i s a t t ri b u t e d t o t he s t r on g trans 1 0 ). S i n c e w a t e r i s e n v i ro n me n t a l l y b e n i g n s o l v e n t
2 8
i n fl u e n c e o f t h e N H C l ig a n d ( T a b le S 1 , S u pp le m en t a ry c o m p a re d t o T H F , t h er e f o r e, o p t i m i s a t i o n o f o t h e r
I n f o r m a t i o n ) . T h e C C a r b e n e-P d-N a n d B r- P d - B r r e ac t i o n v a r i a b l e s s u c h a s c at a l y s t l o ad i n g s , b a s es ,
p y
b o n d a n g l e s a r e a t 1 7 6 . 7 1 (3 ) a n d 1 7 7 . 8 1 (4 ) c o n s i s t en t t e m p e ra t u r es , e t c . w a s c ar r i e d o u t i n w a t e r u n d e r
w i t h d i st o r t e d s qu a r e p l a na r g e om e t ry o f t h e m et al r e flu x i n g c o n d i t i o n i n p r e s e n c e o f T B A B a n d t h e
c en t e r . T h e c r y s t a l i s s t a bi li z e d b y w e a k i n t e r a ct i o n s r e s u l t s a re d i s p l a y e d i n T a b l e 1 . T o fi n d o u t t h e b e s t
n a m e l y C 2 - HÁÁÁB r 3 , C 2 2 - HÁÁÁO 1 a n d C 2 7 -HÁÁÁF 1 b a s e f o r o u r s y s t e m, w e h a v e t e s t ed t h e c o m m o n l y
H - b o nd s a s s h o wn i n F i g u r e S 1 3 ( S up p l e m e n t a r y a v a i l a b l e i n o r g a n i c b a s e s l i k e N a C O , K O H , N aO H
2
3
t
I n f o r m a t i o n ) .
a
n
d
K
O
B
u
u
s
i
n
g
c
o
m
p
l
e
x
1
a
s
a
c
a
t
a
l
y
s
t
.
I
t
h
a
s
b
e
e
n
o b s er v ed t h at a ct i v i t i e s o f K C O a n d N a C O a r e
3
2
3
2
c o m p a ra b l e, ( e n t r i e s 8 & 1 5 ) w h i l e N a O H s h o we d t h e
l o w es t a ct i v i t y ( en t r y 1 6 ) . T h e t e m p e ra t u r e o p t i m i za -
t i o n s t u d y r ev ea l s t h at a t e m p e ra t u r e o f 1 0 0 °C i s
e s s e n t i a l t o o b t a i n n e a r l y q u an t i t a t i v e c o n v er si o n o f
t h e p r o d u c t ( en t r y 9 ) . W h e n t h e t e m p e ra t u r e w as
d e c re a s e d t o 8 0 °C , a s u b s t a n t i al d r o p i n t h e c o n v e r -
s i o n o f t h e p r o d u c t w a s n o t i c e d ( en t r y 1 1 ). I n f a c t , a t
r o o m t e m p e ra t u r e, t h e r e ac t i o n d i d n o t p r o c e ed a t a l l .
L i k e t e m p e ra t u r es , t h e c at al y s t l o ad i n g s a n d t h e
r e ac t i o n t i me s a l s o h a v e s o m e i m p a c t o n o u r c a t a l y t i c
s y s t e m. W h e n t h e c at al y s t l o ad i n g w a s r e d u c ed f r o m 1
m o l % t o 0 . 5 m o l % , t h e p r o d u c t c o n v e r s i o n w as
d e c r ea s e d t o 5 9 % ( e n t r y 1 4 ). T h e o p t i m a l c o n d i t i o n
f o r o u r c at a l y t i c s y s t e m s t an d s o u t t o b e : 1 m o l % 1,
K C O ( 3 e q u i v a l e n t s ) a s a b a s e , T B A B ( 1 . 5 e q u i v a -
3 . 2 Mizoroki-Heck reaction catalysed by Pd-
PEPPSI complex
T h e p r o p o s e d M i z o ro k i -H e c k r e a c t iv it y o f o u r c at al y s t
1 w as i n ve s t i g at e d i n m o d e l r e a c t io n b e t w e e n b r o -
m o b e n z e ne a n d s t y re n e i n c o m m o n s o l v e n t s s u c h a s
N,N- d i m e t h yl f o r m am i d e ( D M F ) , t ol u e n e , t e t r ah y d r o -
f u r a n ( T H F ) a n d w a t e r , i n t h e p r e s e n c e o f b a s e K C O
2
3
2
3
l e n t s ) , w a t e r a s t h e s o l v e n t , 1 0 0 °C a s t h e r e a c t i o n
t e m p e ra t u r e. I t i s i n t e re s t i n g t o n o t e t h at u n d e r o p t i -
m i z ed c o n d i t i o n s w h e n t h e e f fic i e n c y o f t h e b i s- p y r-
i d i n e c o m p l e x 1a w a s e x a mi n e d i n t h e m o d e l r e a ct i o n ;
n o p r o d u c t w a s f o r me d s u b s t a n t i at i n g t h e P E P P S I
i n flu en ce i n t h e c at al y t i c p r o c e s s ( en t r y 1 9 ) .
Figure 4. S y m m e t r y i n d e p e n d e n t m o l e c u l e s o f 1 f o r m a
c h a i n a lo n g [ 0 1 0 ] a x i s .

5 1 P a g e 6 o f 1 0
J. Chem. Sci. ( 2 0 2 0 ) 1 3 2 : 5 1
Table 1. O p t i m i z a t i o n o f r e a c t i o n v a ri a b l e s f o r P d - P E P P S I c o m p le x 1 c a t a l y z e d M i z o r o k i - H e c k c r o s s - c o u p li n g r ea c-
t io n s .
a
1
(1mol%)
+
Br
base, TBAB
12 h
b
E n t r y
T ( °C )
S o l v e n t
B a s e
A d d it i v e
C o n v er s i o n
1
2
3
4
5
6
7
8
1 4 0
1 0 0
1 0 0
6 6
1 4 0
1 1 0
6 6
1 0 0
1 0 0
1 0 0
8 0
6 0
3 0
1 0 0
1 0 0
1 0 0
1 0 0
1 0 0
1 0 0
D M F
H O
T o l u e n e
T H F
D M F
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
K C O
2
N a C O
2
N a O H
K O H
–
–
–
–
0
0
0
3
3
3
3
3
3
3
3
3
3
3
3
3
3
2
0
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
T B A B
1 1
2 5
8 2
8 4
9 5
T o l u e n e
T H F
H O
2
9
H O
2
H O
2
H O
2
H O
2
H O
2
H O
2
H O
2
H O
2
c
1 0
1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
0 0
4 5
4 1
0 0
d
5 9
7 8
4 2
4 8
5 6
3
H O
2
H O
2
H O
2
K O tB u
K C O
e
0 0
2
3
a
R e a ct i o n c o nd it i on : 1 m m o l b r o m o b e n z e n e , 1 . 5 m m o l s t y r e n e , 1 . 5 m m o l T B A B , b a s e ( 2 m m o l , e n t r i e s 1 - 8 , 3 m m o l , e nt r i es
9 - 19 ) a nd 1 m o l % 1 a r e h e a t e d f o r 1 2 h a t m e n t i o n e d t e m p e r a t u r e . C o n v e r s i o n i s d e t e r m i n e d b y G C , a b s e n c e o f 1 d 1 ( 0. 5
m o l % ) , C o m pl e x 1a.
b
c
e
T o c h e c k t h e g e n e r a l a p p l i c a bi li t y o f o u r c at a l y t i c H e n c e, w e w e re i n t r i g u ed t o s e e i f a n y s u c h
s y s t e m , w e h a v e e x pl o re d t he c a t a l yt ic p e rf o r m an ce n a n o p ar t i cl e s w e re g e n e r at ed i n o u r c as e. H o w e v e r, i n
o f o u r c o m p l e x 1 f o r a r a n g e o f r e p re s e n t a t i v e a r y l o u r c as e, n o n a n o p ar t i cl e s w e r e g e n e r at e d a s o b se r v e d
b r o m i d e s a n d i o di d e s . I t i s o b s e r v e d t ha t b o t h e l e c- b y t r a n s m i s s i o n e l e c t r o n m i c ro s c o p y ( T E M ) a n a l y si s
t r o n - d o n a t i n g ( T a bl e 2 ; e n t ri e s 3 , 4 , 8 , 1 0 ) a n d ( Fi g u r e S 1 4 , S u p p l em e n t ar y I n f o r m at i o n ).
e l ec t r o n- w i t hd ra wi n g p a r a a n d m e ta s u bs t it u t ed ( en -
2 8
B as ed o n t h e l i t e r at u r e r ep o r t s , w e p r o p o s e d a
t r i e s 5 - 7 & 1 1 - 1 3 ) a r y l b r o m id e s / io d id e s f a i r l y r ea c t p l au s i b l e r ea c t i o n p a t h w ay i n S ch em e 2. I t i s w el l -
w i t h s t y r en e t o g i v e c o r re s p o n d i n g c o u p l in g p r o d u ct s d o c u m e n t e d t h at P d - N H C c o m p l e x e s b e a ri n g t h r o w -
i n m od er a t e t o e x c e ll e nt y i e ld s . H o w e v e r, o r t h o - a w ay l i g a n d s i n t h e p r e s e n c e o f T B A B, f o rm s a n
s u b s t i t u t e d a r y l h a l i d e s r e l uc ta nt t o p a rt i c i p a t e i n t h e a n i o n i c c o m p l e x , T B A [ (N H C ) P dB r ] w h i ch i n t u r n
3
r e a c t i o n a s t h e c o nv e r s io n o f t he p r o du c t g a v e o n l y a ct s a s a n a ct i v e p r e ca t a l y s t i n t h e r ea c t i o n . T h e r e a f t e r ,
1 8 % w h e n 2 - i od ot o l u e n e w a s e m pl o y e d a s a c o u p l i n g a t h i g h t e m p e ra t u r e, i n t h e p r e s e n c e o f K C O , N HC -
p a r t n e r ( E n t r y 9 ) . U s u a l l y , t he r e a c t io n s w i t h a ry l P d ( I I) c o m p l e x r ed u c ed t o c o r r es p o n d i n g N H C - P d ( 0 )
2
3
-
i
o
d
i
d
e
s
r
e
q
u
i
r
e
d
l
e
s
s
r
e
a
c
t
i
o
n
t
i
m
e
c
o
m
p
a
r
e
d
t
o
c
o
r
-
a
n
d
i
n
o
u
r
c
a
s
e
,
p
o
s
s
i
b
l
y
f
o
r
m
e
d
[
(
N
H
C
)
P
d
(
0
)
B
r
]
r e s p o n d i n g a r y l b r o m id e s ( e n tr y 3 v s 4 ; e n t ry 1 1 v s t h at c o u l d i n i t i at e t h e r e ac t i o n . A f t e r t h e f o r m a t i o n o f
1 2 ) . O u r s y s t e m f a i le d t o a c t iv a t e c h l or oa re n e s a n d t h e c at a l y t i ca l l y a ct i v e P d ( 0 ) s p e c i e s , t h e c a t a l y t i c
h e t e r oa ry l h a l i d e s a s s u b s t ra te s i n w a t e r ( e n t r i e s c y c l e c o u l d b e s u m m ar i s ed b y f o u r m ai n s t e p s,
1
4
-
1
6
)
.
n a m el y , o x i d a t i v e a d d i t i o n o f a r y l h a l i d e t o p a l l a d i u m
I t m a y b e i m p o r ta n t t o m e nt i on t ha t t h e re i s l i t e r a- c en t e r , c o - o r d i n at i o n o f s u b s t r a t e s s t y r en e, m i g ra t o r y
2
9
t u r e e v i d e n c e w he r e P d -N H C c o m p le x e s o f t e n g e n - i n s e rt i o n a n d b- h y d ri d e s y n e l i m i n at i o n t o d e l i v e r t h e
e r a t e P d n a n o p a r t ic le s u n d e r c a t a l yt ic c o n d i t i o n . p r o d u ct .

J. Chem. Sci. ( 2 0 2 0 ) 1 3 2 : 5 1
P
a
g
e
7
o
f
1
0
5
1
a
Table 2. P d - P E P P SI c o m p l e x c a t a l y z e d M i z o ro k i - H e c k c r o s s - c o u p l in g r e a c ti o n s o f d i f f e r e n t a r y l h a l i d e s w i t h s t y r en e .
K CO , TBAB
2
3
+
X
H O, Temp
2
R
R
.
b
E
n
t
r
y
R
X
T
i
m
e
(
h
)
C
o
n
v
e
r
s
i
o
n
(
%
)
c
1
2
3
4
5
6
7
8
H
H
B r
I
B r
I
B r
I
B r
B r
I
I
B r
I
B r
C l
C l
1 2
5
1 2
5
1 2
5
1 2
1 2
1 2
5
1 2
5
1 2
1 2
1 2
1 2
9
5
(
9
0
)
9 6
8 2
9 3
9 1
9 2
7 5
9 0
1 8
8 2
4 - O M e
4 - O M e
4 - N O
4 - N O
3 - N O
4 - C H
2 - C H
3 - C H
4 - C OC H
4 - C OC H
4 - C HO
H
2
2
2
3
9
3
1 0
1 1
1 2
1 3
1 4
1 5
1 6
3
c
1 0 0 ( 9 4)
1 0 0
9 7 ( 9 2)
3
3
c
T r a c e
T r a c e
T r a c e
4 - N O
2 - B ro m o p y r i d i n e
2
a
C o n d i t io ns : A r y l h a l i d e ( 1 m m o l ) , s t y r e n e ( 1 . 5 m m o l ) , K C O ( 3 m m o l ) , H O ( 3 m L ) , T B A B ( 1 .5 m m o l ) , r e a c ti o n t i m e :
2
3
2
b
c
5 -1 2 h ; 1 ( 1 . 0 m o l % ), T e m p : 1 0 0 °C ; C o n v e rs i o n i s d e t e r m i n e d b y G C . I s o la t e d y i e l d s .
Scheme 2. P o s s i b l e m e c h a n i s m f o r t h e P E P P S I P d - N H C c a t a l y s e d M i z o r o k i - H e c k r e a c t io n .

5 1 P a g e 8 o f 1 0
J. Chem. Sci. ( 2 0 2 0 ) 1 3 2 : 5 1
P a l la d iu m P r e c a ta l y s t s : C a t a ly ti c A p p l i c a t io n i n B u c h-
w a l d – H a r t w i g A m i n a t i o n i n A i r J. Org. Chem. 82 2 91 4 ;
( d ) Z e i l e r A , R u d o l p h M , R o m i n g e r F a n d H a s h m i A S
K 2 0 1 5 A n A l t e r n a ti v e A p p r o a c h t o P E P P SI C at a l ys t s :
F r o m P a l la d iu m I s o n i t r i le s t o H i g h l y A c t i v e U n s y m -
m e t r i c a l ly S u b s t i tu te d P E P P SI C a t a ly s t s Chem. Eur. J.
21 1 1 0 6 5 ; ( e ) A k k o c S , I l h a n I O , G o k Y , K ay s e r V
2 0 1 7 C a r b o n - c a r b o n b o n d f o r m a t io n c a t a l y ze d b y
P E P P SI P d - N H C Inorg. Chim. Acta 461 5 2
4. Conclusions
I n s u m m a r y , w e h a ve r e p o r te d t h e s y nt h e s i s o f a n a i r
a n d m o i s t u r e s t a bl e P E P P S I- P d -N H C c o m p l e x a n d
e x p l o r ed i t s c a t a l yt ic p o t e n ti a l f o r M i z o r o k i - H e ck
c r o s s - c o u p l i n g r e a c t i o n . T h e s t r u c tu re o f t h e c o m p l e x
1 w a s d e t e r m i n ed b y X - ra y s i n gl e - c r y s t a l a n a l y s i s .
P r e s e nt s t u d i e s r e p r e s e n t t h e fi r s t u s e o f P E P P S I - Pd -
N H C c a t a l ys t f o r t h e M i z o r o k i - H e c k c r o s s - c o u p l i ng
r e a c t i o n s i n a q u e ou s m e di a w h e re g o o d - to -e x c e ll e n t
y i e l d s o f c r o s s - c o u p l i n g p r o du c t s a r e o b t a i n e d .
3 . B a l in g e K R a n d B h a g a t P R 2 0 1 7 P a l la di u m – N -
h e t e r o c y c l i c c a r b e n e c o m p l e x e s f o r t h e M i z o r o k i –H ec k
r e a c t io n : A n a p p r a i s a l C. R. Chimie. 20 7 7 3
4 . O r ti z A , S a l P G , F l o r e s J C a n d J e s u s E d e 2 0 1 8 H i g hl y
R e c o v e r a b l e P d ( I I ) C a t a ly s ts f o r t h e M i z o r o k i –H ec k
R e a c t io n B a s e d o n N - H e t e r o c y c l ic C a r b e n e s a nd
P o l y ( b e n z y l e t h e r ) D e n d r o n s Organometallics 37 3 59 8
5 . M a M T a n d L u J M 2 0 1 2 D i n u c l e a r P d ( I I )– N H C
c o m p le x d e r iv e d f r o m p r o l in e a n d i ts a p p l i c a t io n t ow ar d
M i z o r o k i – H e c k r e a c ti o n p e r f o r me d i n w a t e r Appl.
Organomet. Chem. 26 1 7 5
6 . H e r r m a n n W A , B o h m V P W , G s t o t t m a y r C W K ,
G r o s c h e M , R e i s in g e r C P a n d W e s k a m p T 2 00 1
S y n t h e s i s , s t r u c t u r e a n d c a t a l y t i c a p p l i c a t io n o f p al l a -
d i u m ( I I ) c o m p l e x e s b e a r i n g N- h e te r o c y c li c c ar be n es
a n d p h o s p h i n e s J. Organomet. Chem. 617 6 1 6
7 . ( a ) Y u a n D , T e n g Q a n d H u y n h H V 2 0 1 4 T e m p l at e -
D i r e c te d S y n t h e s i s o f P a l la d iu m ( I I ) S u l f o n a te - N H C
C o m p l e x e s a n d C a t a ly t i c S t u d i e s i n A q u e o u s M i z o r-
o k i-H e c k R e a c t io n s Organometallics 33 1 79 4;
( b ) G u¨ l c e m a l S , K a h r a m a n S , D a r a n J C , C¸ e t i nk a ya E
a n d C¸ e t i n k a y a B 2 0 0 9 T h e s y n t h e s i s o f o l i g o et h er -
s u b s t i tu t e d b e n z im i d a z o l i u m b r o m i d e s a n d t h e i r u s e a s
l ig a n d p r e c u r s o r s f o r t h e P d - c a ta ly z e d H e c k c o u p l i ng i n
Supplementary Information (SI)
F ig u r e s S 1 –S 2 1 , T a b l e S 1 a n d C I F fi l e s a r e a v a il a b l e a t
w w w . i a s . a c. i n/ c h em s c i .
Acknowledgements
W e g r a t ef u l l y a ck n o w l e d g e t h e fi n a n c i a l s u p p o rt f r o m t h e
D e p ar t m en t o f S c i e n c e a n d T e c h n o l o g y , N e w D e l h i ( G r a n t
n o : C RG / 2 0 1 8 / 0 0 1 6 6 9 ) U GC , N e w D e l h i f o r S A P - D R S
g ra n t t o t h e D e p a r t m e n t o f C h e m i s t r y , D i b r u g a r h U n iv e r -
s it y . D B i s t h an k fu l t o U GC , N E R O f o r p r o v i d i n g a
t e a c he r ’ s f e l l ow s h i p u n d e r F IP p r o g r a m m e .
Conflicts of interest T h e r e a r e n o c o n fl i c t s t o d e c la r e .
¨
w a t e r J. Organomet. Chem. 694 3 5 8 0 ; ( c ) S c h o n fe l de r
References
D , N u y k e n O a n d W e b e r s k i r c h R 2 0 0 5 H e c k a n d S u z uk i
c o u p l in g r e a c ti o n s i n w a t e r u s i n g p o l y ( 2 - o x a zo l i n e )s
f u n c t io n a l i z e d w i t h p a l l a d i u m c a r b e n e c o m p l ex es a s
s o l u b l e , a m p h ip h i li c p o l y m e r s u p p o r t s J. Organomet.
Chem. 690 3 5 8 0 ; ( d ) S c h o 1 n f e l d e r D , F i s ch e r K ,
S c h m i d t M , N u y k e n O a n d W e b e r s k ir c h R 2 00 5
P o l y ( 2 - o x a z o li n e ) s F u n c t i o n a l i z e d w i t h P a l l a d i u m C a r -
b e n e C o m p l e x e s : S o l u b l e , A m p h ip h i l ic P o l y m e r S u p -
p o r t s f o r C - C C o u p l i n g R e a c t io n s i n W a t er
1 . S e l e ct e d e xa m p l e s : ( a ) H su Y C , S h e n J S , L i n B C ,
C h en W C , C h a n Y T , C h i n g W M , Y a p G P A , H s u C P
a n d O n g T G 2 0 1 5 S y n t h e s i s a n d I s o l a t i o n o f a n A c y c li c
T r id e n t a te B i s( p y r i d i n e ) c a rb o d i c a r b e n e a n d S t u d i e s o n
I t s S t r uc t u r a l I m p l i c a t i o n s a n d R e a c t i v i t i e s Angew.
Chem. Int. Ed. 54 2 4 2 0 ; ( b ) G o n z a l e z S D , M a r i o n N
a nd N o l a n S . P 2 0 0 9 N -H e t e r o c y c l i c C a rb e n e s i n L a t e
T r a n s i t i o n M et a l C a t a l y s i s Chem. Rev. 109 3 6 1 2 ;
( c ) S c h a p e r L A , H o c k S J , H e r rm a n n W A a n d K u¨ h n
F E 2 0 1 3 S y nt h e s i s a n d A p p l i c a t i o n o f W a t e r - S o l u b l e
N H C T r a n s i t io n - M e t a l C o m p l e x e s Angew. Chem. Int.
Ed. 52 2 7 0 ; ( d ) H o p k i n s o n M N , R i c h t e r C , S c h e d l e r M
a n d G l o r i u s F 2 0 1 4 A n o v e r v i e w o f N -h e t e r o c y c l i c
c ar b en e s Nature 510 4 8 5 ; ( e ) G u r b u z N , K a r a c a E O ,
O z d em i r I a nd C e t i n k a y a B 2 0 1 5 C r o ss c o u p l in g
r e ac t i o ns c at al y z e d b y ( NH C ) P d ( I I) c o m p l e x e s Turk.
J. Chem. 39 1 1 1 5
¨
Macromolecules 38 2 5 4 ; ( e ) O z d e m ir I , G u¨ r bu¨ z N ,
¨
G ok Y a n d C¸ e t i n k a y a B 2 0 0 8 N- f u n c t i o n a l i z e d a zo l i n-
2 - y li d e n e - p a l la d i u m - c a ta ly z e d H e c k r e a c ti o n Heteroa-
tom Chem. 19 8 2
8 . S e l e c t e d e x a m p l e s : ( a ) O ’ Br ie n C J , K a n tc h e v E A ,
V a l e n te B C , H a d e i N , C h a s s G A , L o u g h A , H o p k i ns o n
A C a n d O r g a n M G 2 0 0 6 E a s i l y P r e p a r e d A i r - a nd
M o i s t u r e S t a b l e P d – N H C ( N H C = N - H e t e r o c y c l ic C a r -
b e n e ) C o m p l e x e s : A R e l ia b l e , U s e r - F r i e n d l y , H i g hl y
A c t i v e P a l la d i u m P r e c a t a l y s t f o r t h e S u z u k i– Mi y au ra
R e a c t io n Chem. Eur. J. 12 4 7 4 3 ; ( b ) O r g a n M G , H a di
M A , A v o l a S , H a d e i N , N a s i e l s k i J , O ’ B r i e n C J a nd
V a l e n te C 2 0 0 6 B ia r y l s M a d e E a s y : P E P P SI a nd t he
K u ma d a – T a m a o – C o r r i u R e a c t io n Chem. Eur. J. 13 1 50 ;
( c ) O r g a n M G , C a l im s i z S , S a y a h M , H o i K a n d L ou gh
A J 2 0 0 9 P d - P E P P S I - I P e n t : A n A c t i v e , S t e ri c a ll y
D e m a n d i n g C r o s s - C o u p l i n g C a t a l y s t a n d I t s A p pl i c a-
t io n i n t h e S y n t h e s i s o f T e t r a - Ortho- S u b s t i tu te d B i a r y ls
Angew. Chem. Int. Ed. 48 2 3 8 3 ; ( d ) C¸ a l i m si z S , S a y ah
2 . S e l ec t e d e x am p l e s : ( a ) L u D D , H e X X a n d L i u F S
A
n
2 0 1 7 B u lk y Y e t F l e x i b l e P d - P E P P SI - I Pe n t f o r t h e
S y n t h e s i s o f S t e r i c a l l y H i n d e r e d B i a r y l s i n A i r J. Org.
Chem. 82 1 0 8 9 8 ; ( b ) M e i r i e s S , D u c G L , C h a r t o i r e A ,
C o ll a d o A , S p ec k K , A ra c h c h i g e K S A , S l a w i n A M Z
a n d N o l a n S P 2 0 1 3 L a r g e y e t F l e x i b l e N -H e t er o c y c l ic
C ar b en e L i g an d s f o r P a l l a d i u m C a t a l y s i s Chem. Eur. J.
19 1 7 3 5 8 ; ( c ) L a n X B , L i Y , L i Y F , S h e n D S , K e Z
a n d L i u F S 2 0 1 7 F l e x i b l e S t e r i c B u l k y B i s (I m i n o ) a c e -
n a ph th e ne ( B I A N ) -S u p p o r t e d N -H e t e r o c y c l i c C a r b e n e

J. Chem. Sci. ( 2 0 2 0 ) 1 3 2 : 5 1
P a g e 9 o f 1 0 5 1
M , M al l i k D a n d O r g a n M G 2 0 1 0 P d - P E PP S I - I P e n t :
L o w - T e mp e r a t u r e N e g i s h i C r o s s- C o u p l i n g f o r t h e
P r ep a r a t i o n o f H i g h l y F u n c t i o n a l i z e d , T e t ra - ortho- S u b -
s t i tu t e d B i ar yl s Angew. Chem. Int. Ed. 49 2 0 1 4 ; ( e ) H o i
K H , C al i m s i z S , F ro e s e R D J , H o p k i n s o n A C a n d
O r g an M G 2 0 1 2 A m i n a t i o n w i t h P d - NH C C o m p l e x e s:
R at e a n d C o m p u t a t i o n a l S t u d i e s I n v o l v i n g S u b s t i tu te d
A n i l in e S u b s t r a t e s Chem. Eur. J. 18 1 4 5
C o l la b o r a t i v e ( N- H e t e r o c y c l i c C a r b e n e ) - Co p p er a nd -
P a l la d iu m C o m p l e x e s Org. Lett. 16 3 7 2 4 ; ( c ) B o u b ak ri
L , Y a s a r S , D o r c e t V , R o i s n e l T , B r u n e a u C , H a m di b N
a n d O z d e m i r I 2 0 1 7 S y n t h e s i s a n d c a t a l y t i c a p p l i ca t i on s
o f p a l l a d i u m N - h e t e r o c y c l i c c a r b e n e c o m p l e x es a s
e f fi c i e n t p r e - c a t a l y s t s f o r S u z u k i – M i y a u r a a n d S o n o-
g a s h ir a c o u p l i n g r e a c t io n s New J. Chem. 41 5 1 0 5
1 2 . ( a ) P a n y a m P K R , U g a le B a n d G a n d h i T 2 01 8
P a l la d iu m ( I I ) / N - H e t e r o c y c l i c C a r b e n e C a t a ly z e d O n e-
P o t S e q u e n t i a l a- A r y l a t io n / A l k y l a t i o n : A c c e s s t o 3 ,3 -
D i s u b s t it u t e d O x in d o l e s J. Org. Chem. 83 7 62 2;
( b ) K a l o g lu N , K a l o g lu M , T a h i r M N , A r i ci C ,
B r u n e a u C , D o u c e t H , D i x n e u f P H , C¸ e t i n k a y a B a nd
O z d e m i r I 2 0 1 8 S y n t h e s i s o f N- h e te r o c y c li c c a rb e ne -
p a l l a d i u m - P E P P S I c o m p l e x e s a n d t h e i r c a t a l y t i c a ct i v-
i ty i n t h e d i r e c t C - H b o n d a c t i v a t io n J. Organomet.
9 . ( a ) L a n X B , C h e n F M , M a B B , S h e n D S a n d L i u F S
2 0 1 6 P d - P E P P S I C o m p l e x e s B e a r i n g B u l k y [ ( 1 , 2 - D i -
( tert- b u t y l ) a ce n a p h t h y l ] ( D t B u - A n ) o n N- He t e r o c a r b e n e
B ac k b on e s : H i g h l y E f fi c i e n t f o r S u z u k i – M i y a u r a C r o s s -
C o up l i n g u n d e r A e ro b i c C o n d i t i o n s Organometallics 35
3 8 5 2 ; ( b ) T o u j N , G u r b u z N , H a m d i N , Y a s¸ a S a n d
O z d em i r I 2 0 1 8 P a l l a d i u m P E PP S I c o m p l e x e s : S y n t h e -
s i s a nd c at al y t i c a c t i v i t y o n t h e S u z u k i - M i y a u r a
c o up li n g r e ac t i o n s f o r a r y l b r o mi d e s a t r o o m t e m p e r -
a tu r e i n a qu eo u s m e d i a Inorg. Chim. Acta 478 1 8 7 ;
( c ) L e i P , M en g G , L i n g Y , A n J a n d S z o s t a k M 2 0 1 7
P d - P E P P S I : P d -N H C P re c a t a l y s t f o r S u z u k i – M i y a u r a
C r o s s - C o u p l i ng R e a c t i o n s o f A m i d e s J. Org. Chem. 82
¨
Chem. 867 4 0 4 ; ( c ) A k ta s¸ A , B a r u t C e l e p c i D a n d G o k
Y 2 0 1 9 N o v e l 2 - h y d r o x y e t h y l s u b s t i tu t e d N- c o or d i na t e -
P d ( I I ) ( N H C) a n d b i s ( N H C ) P d ( I I ) c o m p le x e s : S y n t he s i s ,
c h a r a c t e r i z a ti o n a n d t h e c a t a l y t i c a c t i v i ty i n t h e d i r ec t
a r y la ti o n r e a c t io n J. Chem. Sci. 131 7 8
6 6 3 8 ; ( d ) S t e ep l e s E , K e l l i n g A , S c h i l d e U a n d E s p o si t o 1 3 . V a l e n te C , P o m p e o M , S a y a h M a n d O r g a n M G 2 01 4
D 2 0 1 6 A m i n o a c i d - d e ri v e d N -h e t e r o c y c l i c c a r b e n e
p a ll a d i um c om p l e x e s f o r a q u e o u s p h a s e S u z u k i –
M i ya u r a c ou pl i n g s New J. Chem. 40 4 9 2 2 ; ( e ) N a v a D 1 4 . ( a ) L u H , W a n g L , Y a n g F , W u a R a n d S h e n W 2 01 4
C a r b o n – H e t e r o a t o m C o u p l i n g U s i n g P d - P E P P S I C o m -
p l e x e s Org. Proc. Res. Dev. 18 1 8 0
R , H e r n a nd e z A A , R h e i n g o l d A L , C a s t i l l o O R S a n d
E s p i n o s D M 2 0 1 9 H y d ro x y l - fu n c t i o n a l i z e d t r ia z o l y l i -
d e ne - b a s e d P E PP S I c o m p l e x e s : m e t a l l a c y c l e f o r m a t i o n
e f f e ct o n t h e S u z u k i c o u p l i n g r e a c t i o n Dalton Trans. 48
3 2 1 4 ; ( f ) I m i k F , Y a s¸ a r S a n d O z d e m i r I 2 0 1 9 S y n t h e s i s
a n d i n v es t ig at i o n o f c a t a l y t i c a c t i v i t y o f p h e n y l e n e –
A n d b i p h en y l en e b r i d g e d b i m e t a l l i c P a l l a d i u m- P E P P S I
c o mp l e x e s J. Organomet. Chem. 896 1 6 2 ; ( g ) K a l o g l u
N a nd O z d e m i r I 2 0 1 9 P E PP S I - Pd - NH C c a ta ly z e d
S u z u k i - M i y au r a c r o s s - c o u p l i n g r e a c t i o n s i n a q u e o u s
m ed i a Tetrahedron 75 2 3 0 6 ; ( h ) S i k o r s k i W , Z a w a r t k a
W a n d T r ze c ia k A M 2 0 1 8 P E P PS I - t y p e c o m p l e x e s
C r o s s - c o u p l in g r e a c t i o n s c a t a l y z e d b y a n N -h e t e ro -
c y c li c c a r b e n e – P d ( I I ) c o m p l e x u n d e r a e r o b i c a nd C u I -
f r e e c o n d i ti o n s RSC Adv. 4 3 0 4 4 7 ; ( b ) L i n Y C , H s ue h
H H , K a n n e S , C h a n g L K , L i u F C a n d L i n I J B 2 01 3
E f fi c i e n t P E P P S I - T h e m e d P a l la d iu m N - H e t e r oc yc l i c
C a r b e n e P r e c a ta l y s t s f o r t h e M i z o r o k i – H e c k R e a ct i on
Organometallics 32 3 8 5 9 ; ( c ) K e s k e E C , Z e n k i n a O V ,
W a n g R a n d C r u d d e n C M 2 0 1 2 S y n t h e si s a n d S t r u ct u re
o f P a l la d i u m 1 , 2 , 3 - T r i a z o l - 5 - y l i d e n e M e s o i o n i c C a r -
b e n e P E P P SI C o m p l e x e s a n d T h e i r C a t a ly ti c A p pl i c a-
t io n s i n t h e M i z o r o k i - H e c k R e a c t i o n Organometallics
31 6 2 1 5
w i t h s m a l l N H C l i g a n d s o b t a i n e d a c c o r d i n g t o t h e n e w 1 5 . A k k o c M , I m i k F , Y a s a r S , D o r c e t V , R oi s ne l T ,
m et h o d e f fi c i en t l y c a t a l y z e d S u z u k i - M i y a u ra r ea c t io n J.
Organomet. Chem. 867 3 2 3 ; ( i ) M o n d a l M , J o j i J a n d
C h o ud h u r y J 2 0 1 8 C o o r d i n a t i o n -p o l y m e r a n c h o r e d
s i n g le - s i t e ‘ P d - N H C ’ c a t a l y s t f o r S u z u k i -M i y a u r a c o u -
p l i n g i n w a t er J. Chem. Sci. 130 8 3
B r u n e a u C a n d O z d e m i r I 2 0 1 7 A n E f fi c i e n t P r o t o co l
f o r P a l la d i u m N - H e t e r o c y c l ic C a r b e n e - C at a ly s ed
S u z u k i - M iy a u r a R e a c t i o n a t r o o m t e m p e r a t u r e Chem-
istrySelect 2 5 7 2 9
1 6 . S A I N T P l u s ( v 6 . 1 4 ) B r u k e r A X S I n c ., M a d is o n, W I ,
2 0 0 8
1 0 . ( a ) Z h a n g Y , L a v i g n e G , L u g a n N a n d C e s a r V 2 0 1 7
B u tt r e s s i n g E f f e c t a s a K e y D e s i g n P ri n c i p l e t o w a r d s 1 7 . B r u k e r A X S I n c ., M a d is o n , W I , 2 0 0 8
H i g h l y E f fi c i e n t P a l l a d i u m / N - He t e r o c y c l i c C a r b e n e 1 8 . S h e l d r i c k G M 1 9 9 7 S H E L X S a n d S H E L X L 9 7 P r o -
B u ch w a ld – H a r t w i g A m i n a t i o n C a t a l y s t s Chem. Eur. J.
23 1 3 7 9 2 ; ( b ) S h a r i f S , R u c k e r R P , C h a n d r a s o m a N ,
¨
g r a m s f o r s t r u c t u r e r e fi n e m e n t a n d s o l u t io n , G o t t i ng e n ,
G e r m a n y
M i tc h e l l D , R o d r i g u e z M J , F ro e s e R D J a n d O r g a n M 1 9 . S p e k A L 2 0 0 2 P L A T O N , A M u l t i p u r p o s e C r y s t a l l o-
G 2 0 1 5 S e l e c ti v e M o n o a r y l a t i o n o f P ri m a r y A m i n e s g r a p h i c T o o l U t r e c h t U n i v e r s it y , U t r e c h t , N e t h e r l an d
U s i n g t h e P d - P E P PS I -I P e n t P re c a t a l y s t Angew. Chem. 2 0 . S p e k A L 2 0 0 3 S i n g l e - c r y s t a l s t r u c t u r e v a l i d a t i o n w i t h
Int. Ed. 54 9 5 0 7 ; ( c ) Y a n g J 2 0 1 7 H e t e r o l e p t i c ( N - t h e p r o g r a m PLATON J. Appl. Cryst. 36 7
h et e r oc y cl i c c a rb e n e ) – P d – p y r a z o l e ( i n d a z o l e ) c o m - 2 1 . R o y B , B a r A K , G o le B a n d M u k h e r j e e P S 2 01 3
C
l
p l ex e s : S y n t h e s i s , c h a r a c t e r i z a t i o n a n d c a t a l y t ic a c t i v -
i t ie s t o w a r d s C – C a n d C – N c r o s s - c o u p l i n g r e a c t i o n s
Appl. Organometal. Chem. 31 3 7 3 4
F l u o r e s c e n t T r i s - I m i d a z o l iu m S e n s o r s f o r P i c r ic A c i d
E x p lo s i v e J. Org. Chem. 78 1 3 0 6
2 2 . J a h n k e M C, H u s s a in M , H u p k a F , P a p e T , A l i S, H a hn F E
a n d C a v e ll K J 2 0 0 9 S y n th e s i s o f p y ra z in e - b r id g e d d i i m -
i d az ol i um s a l t s a nd th ei r a pp l i ca t i o n i n pa l l ad i u m c a t al y z e d
H e c k - t y p e c o u p l i n g r e a c t i o n s Tetrahedron 65 9 0 9
1 1 . ( a ) D a s h C , S h a i k h M M a n d G h o s h P 2 0 0 9 F l u o r i d e -
F r ee H i y a m a a n d C o p p e r a n d A m i n e - F re e S o n o g a s h i r a
C o up l i n g i n A i r i n a M i x e d A q u e o u s M e d i u m b y a
S e r i e s o f P E P P SI - T h e m e d P re c a t a l y s t s Eur. J. Inorg. 2 3 . L o r d P A , N o ll B C , O l m s t e a d M M a n d B a l c h A L
2 0 0 1 A R e m a r k a b l e S k e l e t a l R e a r r a n g e m e n t o f a
C o o r d i n a t e d T e t r a p y r r o le : C h e m i c a l C o n s e q u e n ce s o f
Chem. 1 6 0 8 ; ( b ) G a l l o p C W D , C h e n M T a n d N a v a r r o
2 0 1 4 S o n o g a s h i r a C o u p l i n g s C a t a l y z e d b y
O

5 1 P a g e 1 0 o f 1 0
J. Chem. Sci. ( 2 0 2 0 ) 1 3 2 : 5 1
P a l l ad i u m p- C o o r d i n a t i o n t o a B i l i n d i o n e J. Am. Chem.
Soc. 123 1 0 5 5 4
2 4 . V i o s s a t P B , D u n g N H a n d R o b e r t F 1 9 9 3 S t r u c t u r e
d u trans- d i c hl o r o b i s ( p y r i d i n e ) p a l l a d i u m ( II ) Acta Cryst.
Sect. C C49 8 4
H e c k C o u p l i n g C y c l e s : A C o m b i n e d E x p e r im e n t a l a nd
C o m p u t a t i o n a l S t u d y Organometallics 34 2 46 3;
( b ) S c h r o e t e r F , S t r a s s n e r T 2 0 1 8 U n d e r s t an d i ng
A n io n i c ‘‘ L i g a n d le s s ’’ P a l la d i u m S p e c i e s i n t h e M i z o r-
o k i – H e c k R e a c t i o n Inorg. Chem. 57 5 1 5 9
2 5 . L a n X B , L i Y , L i Y F , S h e n D S , K e Z a n d L i u F S 2 8 . ( a ) J a d h a v S N a n d R o d e C V 2 0 1 7 A n e ffi ci e nt
2 0 1 7 F l e x ib l e S t e r i c B u l k y B i s ( I m i n o ) a c e n a p h t h e n e
( B I A N ) - S u p p o r t e d N -H e t e ro c y c l i c C a rb e n e P al l a d i u m
P r ec a ta l y s t s: C a t a l y t i c A p p l i c a t i o n i n B u c h w a l d - H a r t -
w i g A m i n at i o n i n A i r J. Org. Chem. 82 2 9 1 4
p a l l a d i u m c a t a l y z e d M i z o r o k i – H e c k c r o s s - c o u p l i ng i n
w a t e r Green Chem. 19 5 9 5 8 ; ( b ) C h r i s t o f f e l F a n d W a rd
T R 2 0 1 8 P a l la d iu m - C a t a l y z e d H e c k C r o s s - C o up l i ng
R e a c t io n s i n W a t e r : A C o m p r e h e n s i v e R e v i e w Catal.
Lett. 148 4 8 9
2 6 . H a n Y , H u y n h H V a n d T a n G K 2 0 0 7 S y n t h e s e s a n d
C h ar ac t er i za ti o n s o f P d ( II ) C o m p l e x e s I n c o r p o r a t i n g a 2 9 . K h a z ip o v O V , S h e v c h e n k o M A , C h e r n e n k o A Y ,
N- H et e r o c y c li c C a rb e n e a n d A ro m a t i c N- He t e r o c y c l e s
Organometallics 26 6 4 4 7
2 7 . ( a ) G u e s t D , S i l v a V H M , B a t i s t a A P L , R o e S M ,
B r a g a A A C a n d N a v a r r o O 2 0 1 5 ( N- H e t e r o c y c l i c
C ar b en e ) - P al l ad a t e C o m p l e x e s i n A n i o n i c M i z o r o k i –
A s t a k h o v A V , P a s y u k o v D V , E r e m in D B , Z u b av i ch u s
Y V , K h r u s t a l e v V N , C h e r n y s h e v V M a n d A n an i ko v
V P 2 0 1 8 F a s t a n d S l o w R e l e a s e o f C a t a l y ti c a l l y A c t iv e
S p e c i e s i n M e t a l / N H C S y s t e m s I n d u c e d b y A l ip h at i c
A m i n e s Organometallics 37 1 4 8 3