Palladium(II) and nickel(II) complexes bearing N,N,O-chelate ligands: Syntheses, characterization and catalysis in Heck and Kumada coupling reactions

Article abstract of DOI:10.1002/ejic.200700347

Two new anionic ligands, namely [2-{OC(Ph)₂CH ₂}-6-(3,5-Me₂C₃HN₂)C ₅H₃N]^- (L1^-) and [2-{OC(Ph)=CH}-6-(3,5-Me₂C₃HN₂)C ₅H₃N]^- (L2^-), and their palladium and nickel complexes, were synthesized and characterized. 6-(3,5-Dimethyl-1H- pyrazol-1-yl)-2-methylpyridine was lithiated with nBuLi and the lithiated product treated with benzophenone to give Li(L1) (2), whereas treatment of 2-[6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridin-2-yl]-1-phenylethanone with NaH afforded Na(L2) (6). The palladium and nickel complexes [(L1)PdCl] (3), [(L1)NiAr] [Ar = o-MeC₆H₄ (4a), 1-C₁₀H ₇ (4b)], [(L2)PdCl] (7) and [(L2)NiAr] [Ar = o-MeC₆H ₄ (8a), 1-C₁₀H₇ (8b)] were obtained by ligand-transfer reactions between Li(L1) or Na(L2) and [PdCl₂(PhCN) ₂] or [(Ph₃P)₂Ni(Ar)Cl] (Ar = o-MeC ₆H₄ and 1-C₁₀H₇, respectively). These complexes are diamagnetic and were characterized by NMR spectroscopy and elemental analyses. The structures of complexes 4b and 8a were determined by single-crystal X-ray diffraction techniques. The catalytic activity of the nickel and palladium complexes in the Heck and Kumada cross-coupling reactions were investigated. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejic.200700347

FULL PAPER
DOI: 10.1002/ejic.200700347
Palladium(II) and Nickel(II) Complexes Bearing N,N,O-Chelate Ligands:
Syntheses, Characterization and Catalysis in Heck and Kumada Coupling
Reactions
Zhong-Xia Wang*[a] and Zuo-Yun Chai[a]
Keywords: N,N,O ligands / Palladium / Nickel / Chelates / Homogeneous catalysis / C–C coupling
Two new anionic ligands, namely [2-{OC(Ph)2CH2}-6-(3,5-
Me2C3HN2)C5H3N]– (L1–) and [2-{OC(Ph)=CH}-6-(3,5-
Me2C3HN2)C5H3N]– (L2–), and their palladium and nickel
complexes, were synthesized and characterized. 6-(3,5-Di-
methyl-1H-pyrazol-1-yl)-2-methylpyridine was lithiated with
nBuLi and the lithiated product treated with benzophenone
to give Li(L1) (2), whereas treatment of 2-[6-(3,5-dimethyl-
1H-pyrazol-1-yl)pyridin-2-yl]-1-phenylethanone with NaH
afforded Na(L2) (6). The palladium and nickel complexes
[(L1)PdCl] (3), [(L1)NiAr] [Ar = o-MeC6H4 (4a), 1-C10H7 (4b)],
[(L2)PdCl] (7) and [(L2)NiAr] [Ar = o-MeC6H4 (8a), 1-C10H7
(8b)] were obtained by ligand-transfer reactions between
Li(L1) or Na(L2) and [PdCl2(PhCN)2] or [(Ph3P)2Ni(Ar)Cl] (Ar
= o-MeC6H4 and 1-C10H7, respectively). These complexes
are diamagnetic and were characterized by NMR spec-
troscopy and elemental analyses. The structures of com-
plexes 4b and 8a were determined by single-crystal X-ray
diffraction techniques. The catalytic activity of the nickel and
palladium complexes in the Heck and Kumada cross-coup-
ling reactions were investigated.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
The choice of supporting ligands on the central metal
atoms is crucial to the catalytic behavior of the complexes.
The most often used ligands, which have achieved great suc-
cess in catalysts for the Heck and Kumada reactions, are
tertiary phosphanes. However, phosphane ligands are often
expensive, poisonous, air-sensitive, and prone to degrade at
elevated temperatures;[6] therefore the development of phos-
phane-free ligands is a topic of current interest in this area.
A number of phosphane-free ligands have been examined
for palladium- and nickel-catalyzed Heck and Kumada
couplings, some of which have exhibited excellent behav-
ior.[7] Herein we report the syntheses and characterization
of new N,N,O-chelate ligands and their nickel and palla-
dium complexes as well as the catalytic behavior of these
complexes in the Heck and Kumada coupling reactions.
Introduction
Group 10 metal catalyzed C–C coupling has been recog-
nized as one of the most useful methods for C–C bond for-
mation in organic synthesis and has been well developed
over the past decades.[1] The most frequently used cross-
coupling reactions include the reactions of alkyl halides or
pseudohalides with olefins (Heck reaction) and with nucle-
ophilic organometallic reagents such as Grignard reagents
(Kumada reaction), organozinc reagents (Negishi reaction),
and organotin (Stille reaction), organoboron (Suzuki reac-
tion), and organosilicon (Hiyama reaction) derivatives.[1]
The Heck reaction, which is mainly catalyzed by palladium
complexes, is one of the simplest ways to obtain variously
substituted olefins, dienes, and other unsaturated com-
pounds.[2] Other transition metals can also catalyze this re-
action but they normally exhibit lower catalytic activity.
The Kumada reaction, which was the first reported cross-
coupling (early 1970s),[3] is still attracting attention over 30
years later. Current investigation focuses mainly on the de-
velopment of new catalyst systems and extension of this
reaction to substrates such as organic chlorides.[4] Com-
plexes of Ni, Pd, Fe, Co, and other transition metals have
been used to catalyze this reaction,[1,4,5] although nickel and
palladium complexes are the most attractive and intensively
studied.
Results and Discussion
Syntheses and Characterization of Compounds 2–8b
The syntheses of the compounds discussed in this paper
are shown in Scheme 1. 2-(3,5-Dimethyl-1H-pyrazol-1-yl)-
6-methylpyridine (1) was prepared by treatment of 2-hydraz-
ino-6-methylpyridine with pentane-2,4-dione in acetic acid
according to our previously reported method.[8] Compound
1 was readily lithiated by treatment with LDA and the lithi-
ated product treated with benzophenone to afford [Li{2-
[OC(Ph)2CH2]-6-(3,5-Me2C3HN2)C5H3N}] (2) in good
yield. Complex 2 proved to be a good ligand-transfer rea-
gent in reactions with [PdCl2(PhCN)2] and [(Ph3P)2Ni-
[a] Department of Chemistry, University of Science and Technol-
ogy of China,
Hefei, Anhui 230026, China
Fax: +86-551-360-1592
E-mail: zxwang@ustc.edu.cn
4492
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Palladium(II) and Nickel(II) Complexes of N,N,O-Chelate Ligands
(Ar)Cl] (Ar = o-MeC6H4, 1-C10H7), yielding the corre- pale-yellow solid and was characterized by 1H and 13C
sponding complexes 3, 4a and 4b, respectively. Lithiated 1 NMR spectroscopy and elemental analysis. Complexes 2
was treated with PhCN and subsequently dilute H2SO4 to and 6 are air-sensitive colorless (2) or pale-yellow (6) crys-
afford 2-[6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridin-2-yl]-1- tals. The palladium and nickel complexes are pale-yellow
phenylethanone (5). Treatment of 5 with nBuLi or LDA (3), brown (8a), or red (4a, 4b, 7 and 8b) crystals and are
gave a mixture of the lithiated product and unreacted 5. air-stable in the solid state. The nickel complexes are soluble
However, the reaction with NaH in thf formed [Na{2- in CHCl3, CH2Cl2, and thf, but only slightly soluble in tolu-
[OC(Ph)=CH]-6-(3,5-Me2C3HN2)C5H3N}] (6) cleanly.
ene. The palladium complexes are soluble in CH2Cl2, partly
soluble in thf, and almost insoluble in toluene and Et2O.
Each of the complexes was characterized by NMR spec-
troscopy and elemental analyses and the data were found
to be consistent with their respective structures. In addition,
the diamagnetism of the four-coordinate palladium and
nickel complexes revealed that these complexes have a
square-planar geometry at the respective central metal
atom, which means that the ligand coordinates to the cen-
tral metal atom as an N,N,O-tridentate chelate. This was
confirmed by single-crystal X-ray diffraction analyses of
complexes 4b and 8a.
An ORTEP drawing of complex 4b is presented in Fig-
ure 1 along with selected bond lengths and bond angles.
This complex shows a distorted square-planar geometry
around the nickel atom. The fact that the N1–Ni1–O1 bond
angle [95.73(10)°] is wider than N1–Ni1–N3 [82.54(11)°] is
consistent with the corresponding chelate ring size. Simi-
larly, the Ni1–N1–C15 angle [126.3(2)°] is also wider than
Ni1–N1–C19 [113.6(2)°]. The Ni1–N3 distance of
1.893(2) Å is shorter than that of Ni1–N1 [1.959(2) Å] and
is also much shorter than the distances between the
pyrazolyl nitrogen atoms and the nickel atom in
[NiCl2{NCH2CH2(N2C3HMe2-3,5)}]·H2O [2.0334(19) and
2.069(2) Å, respectively],[9] but similar to the Ni–N dis-
Scheme 1. Ligand and complex syntheses. Reagents and conditions:
(i) LDA, thf, –60 to –20 °C, 20 min, then Ph2CO, –80 °C to room
temp., 12 h; (ii) 2  aqueous solution of HCl, room temp., 1 h;
(iii) [PdCl2(PhCN)2] or [(Ph3P)2Ni(Ar)Br] (Ar = o-MeC6H4 or 1-
C10H7), thf, –80 °C to room temp., 10–30 h; (iv) LDA, thf, –60 to
–20 °C, 20 min, then PhCN, –80 to –20 °C, 30 min, room temp.,
10 h, then 2  aqueous H2SO4, 0 °C to room temp., 10 h; (v) NaH,
thf, refluxing, 12 h.
Treatment of 6 with [PdCl2(PhCN)2] afforded the palla-
dium complex [PdCl{2-[OC(Ph)=CH]-6-(3,5-Me2C3HN2)-
C5H3N}] (7), while treatment of 6 with [(Ph3P)2Ni(Ar)Cl]
(Ar = o-MeC6H4, 1-C10H7) afforded complexes 8a and 8b,
respectively. Attempts to synthesize [Ni(X){2-[OC(Ph)2-
CH2]-6-(3,5-Me2C3HN2)C5H3N}] and [Ni(X){2-[OC(Ph)=
CH]-6-(3,5-Me2C3HN2)C5H3N}] (X = Cl, Br) by treating 2
and 6, respectively, with various nickel compounds such as
[(dme)NiCl2], [(R3P)NiCl2] (R = Ph, Et), [(Ph3P)NiBr2],
and NiBr2 were unsuccessful. Each reaction produced an
Figure 1. ORTEP drawing of complex 4b with thermal ellipsoids
drawn at the 30% probability level. Selected bond lengths [Å] and
angles [°]: Ni1–O1 1.840(2), Ni1–N1 1.959(2), Ni1–N3 1.893(3),
Ni1–C20 1.900(3), C1–O1 1.397(3), C1–C14 1.553(4), C14–C15
1.486(4), N2–N3 1.395(3), N2–C19 1.406(4), N1–Ni1–O1
95.73(10), N3–Ni1–O1 175.05(10), C20–Ni1–O1 86.30(11), N1–
Ni1–N3 82.54(11), N1–Ni1–C20 172.68(12), N3–Ni1–C20
95.98(12), Ni1–N1–C19 113.6(2), Ni1–N3–N2 112.69(18), Ni1–
unidentified white precipitate. The neutral compound 5 is a O1–C1 122.03(18), Ni1–N1–C15 126.3(2).
Eur. J. Inorg. Chem. 2007, 4492–4499
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Z.-X. Wang, Z.-Y. Chai
FULL PAPER
tances in [Ni2{(NSiMe3)2CPh}2] [1.868(5)–1.876(5) Å][10] catalyzed by 0.1 mol-% of 7 under the same conditions af-
and [Ni{(2,6-Me2C6H3)NC(Me)C(H)C(Ph)O}2] [Ni1–N2 = forded the coupling product in only 15% yield (Table 1, En-
1.901(3) Å].[11] The Ni–O and Ni–C distances are within the try 22). The iodides were found to be more reactive than
normal range.
the bromides, and aryl chlorides were completely inert. The
An ORTEP drawing of complex 8a is presented in Fig- electronic effects of the substituents on the aryl ring of the
ure 2 along with selected bond lengths and angles. Complex halides obviously affect the coupling reactions catalyzed by
8a also shows a distorted square-planar geometry at the 7 as both electron-withdrawing and electron-donating
nickel atom and its structural skeleton is similar to that of groups lead to a large decrease of the reactivity of the aryl
complex 4b, although with some differences in the bond bromides (Table 1, Entries 15, 18, 22, 36, 38, and 40). How-
lengths and angles. For example, the Ni1–N1, Ni1–N3, and ever, the electronic effects of the substituents on the aryl
Ni1–C19 distances in 8a are shorter than the corresponding ring of the halides is much smaller in the reactions catalyzed
ones in 4b, while the N1–Ni1–C19 and N3–Ni1–O2 angles by 3 than in the same reactions catalyzed by 7 (Table 1,
in 8a are wider than the corresponding ones in 4a. The C6– Entries 2, 4, 7, 29, 31, and 33). The type of base used also
C7 distance of 1.370(8) Å in 8a is typical of a C–C double affects the reaction. Thus, K2CO3 gave excellent results in
bond. The C5, C6, C7, and O2 atoms are almost coplanar, the catalyst systems tested, while Et3N led to relatively poor
with a torsion angle of 0.5°.
results in most cases.
Complexes 4a, 4b, 8a, and 8b showed similar catalytic
activity, with 0.5 mol-% of catalyst being sufficient to drive
the reaction between PhI and butyl acrylate to completion
with a quantitative yield of coupling product.
The couplings of aryl iodides or bromides with
PhCH=CH2 were also investigated. The nickel complexes
were found to be almost inactive to the coupling reactions,
although the palladium complexes 3 and 7 exhibited cata-
lytic activity. These reactions showed a similar trend with
respect to the reactions between aryl halides and butyl acry-
late. Between 0.5 and 2 mol-% of the catalysts was required
to drive these reactions to completion, depending on the
aryl bromides employed. In addition, each coupling reac-
tion gave only the trans product (by 1H NMR spec-
troscopy); no cis isomer was observed.
de Vries and other researchers have recently reported that
most of the palladium catalysts used for the Heck reaction
decompose to form soluble palladium(0) colloids or nano-
particles at high temperature (higher than 120 °C), and that
this colloidal palladium reacts further with aryl halides to
form anionic intermediates.[12] The reaction temperature is
as high as 120 °C in our reaction system, and thus it seems
that the palladium complexes might have decomposed dur-
ing reaction. However, we did observe different catalytic ac-
tivity between complexes 3 and 7. For comparison, we also
tested the Heck reaction catalyzed by PdCl2 and PdCl2 to-
gether with neutral ligand 2Ј using the same substrates and
reaction conditions as those for 3. The results showed that
PdCl2 alone exhibits very low catalytic activity (Table 1, En-
Figure 2. ORTEP drawing of complex 8a with thermal ellipsoids
drawn at the 30% probability level. Selected bond lengths [Å] and
angles [°]: Ni1–O2 1.840(4), Ni1–N1 1.908(5), Ni1–N3 1.888(5),
Ni1–C19 1.886(6), C5–C6 1.423(8), C6–C7 1.370(8), C7–O2
1.300(6), N2–C1 1.410(7), N2–N3 1.408(6), O2–Ni1–C19 85.1(2),
O2–Ni1–N3 177.2(2), C19–Ni1–N3 96.0(2), O2–Ni1–N1 95.88(18),
C19–Ni1–N1 174.9(2), N1–Ni1–N3 83.2(2).
Catalytic Activity of Complexes 3, 4, 7, and 8 in the Heck
and Kumada Reactions
We first examined the catalytic activity of complexes 3, tries 42 and 44), while PdCl2+2Ј shows good catalytic ac-
4, 7, and 8 in the Heck reaction. The palladium complexes tivity (Table 1, Entries 43 and 45), although a little lower
3 and 7 catalyze the coupling of aryl iodides and bromides than that of 3. This could be because the ligand stabilizes
with butyl acrylate in the presence of a base, whereas under the colloids and prevents their aggregation, as suggested by
similar reaction conditions the nickel complexes only cata- de Vries.[12a] The ligand probably also stabilizes the anionic
lyze the reactions of aryl iodides with butyl acrylate. Com- palladium species formed by reaction of colloidal palladium
plex 3 exhibits a higher catalytic activity than complex 7 in with aryl bromides.
most cases, especially for substrates p-MeC(O)C6H4Br and
The catalytic behavior of complexes 3, 4, 7, and 8 in the
p-MeOC6H4Br. For example, 0.1 mol-% of 3 catalyzes the Kumada cross-coupling reaction was also evaluated. Palla-
coupling of p-MeOC6H4Br with butyl acrylate at 120 °C in dium complexes 3 and 7 were found to catalyze the coup-
NMP in the presence of K2CO3 to give the coupling prod- ling of both aryl iodides and aryl bromides with p-
uct trans-p-MeOC6H4CH=CHCOOnBu in 86% yield MeC6H4MgBr to give the cross-coupling products
(Table 1, Entry 7), while the reaction of the same substrates (Table 2). Complex 7 exhibits a slightly better catalytic ac-
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Eur. J. Inorg. Chem. 2007, 4492–4499

Palladium(II) and Nickel(II) Complexes of N,N,O-Chelate Ligands
Table 1. Coupling of RCH=CH2 (R = COOnBu or Ph) and aryl bromides or iodides catalyzed by complexes 3, 4, 7, and 8.[a]
Entry
R
X
R1
Catalyst
(mol-%)
Solvent
Time
[h]
T
Base
Yield
[%][c]
[°C][b]
1
2
3
4
5
6
7
8
H
H
H
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
I
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
CO2nBu
Ph
3 (0.05)
3 (0.1)
3 (0.5)
3 (0.1)
3 (1)
NMP
NMP
DMF
NMP
NMP
NMP
NMP
NMP
NMP
NMP
DMF
DMF
DMF
NMP
NMP
DMF
DMF
NMP
NMP
DMF
NMP
NMP
NMP
NMP
NMP
NMP
DMF
DMF
NMP
NMP
NMP
NMP
NMP
NMP
NMP
NMP
NMP
NMP
NMP
NMP
NMP
NMP
NMP
32
32
20
32
12
3
120
120
120
120
120
100
120
100
120
120
120
120
110
120
120
120
120
120
120
120
100
120
100
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
K2CO3
K2CO3
K2CO3
K2CO3
NEt3
62
98
98
93
82
98
86
98
78
97
99
99
99
52
95
78
93
22
46
62
98
15
98
75
18
99
99
99
89
99
93
93
88
94
trace
94
98
22
97
16
97
24
88
p-MeCO
p-MeCO
p-MeCO
p-MeO
p-MeO
o-Me
o-Me
H
3 (1)
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
NEt3
3 (0.1)
3 (1.3)
3 (0.1)
3 (1)
32
3
9
32
12
12
12
10
32
32
24
32
32
20
20
12
32
3
12
32
12
12
12
32
15
32
15
32
24
48
32
12
32
24
32
24
32
32
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
4a (0.5)
4b (0.5)
7 (0.001)
7 (0.05)
7 (0.1)
7 (0.1)
7 (0.2)
7 (0.1)
7 (0.2)
7 (0.2)
7 (0.5)
7 (0.1)
7 (1)
H
H
H
H
H
H
I
I
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
I
p-MeCO
p-MeCO
p-MeCO
p-MeCO
p-MeO
p-MeO
p-MeO
o-Me
o-Me
H
NEt3
K2CO3
K2CO3
NEt3
7 (1)
7 (0.1)
7 (0.5)
8a (0.5)
8b (0.5)
3 (0.1)
3 (0.8)
3 (0.1)
3 (1.5)
3 (0.1)
3 (2)
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
H
H
I
Br
Br
Br
Br
Br
Br
I
Br
Br
Br
Br
Br
Br
Br
Br
p-Me
p-MeCO
p-MeCO
p-MeO
p-MeO
H
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
4a (2)
H
7 (0.1)
7 (0.5)
7 (0.1)
7 (1.5)
7 (0.1)
7 (2)
p-Me
p-MeCO
p-MeCO
p-MeO
p-MeO
H
CO2nBu
CO2nBu
PdCl2 (0.1)
PdCl2 (0.1)
+ 2Ј (0.1)
PdCl2 (0.5)
PdCl2 (0.5)
+ 2Ј (0.5)
H
44
45
H
H
Br
Br
Ph
Ph
NMP
NMP
32
32
120
120
K2CO3
K2CO3
64
95
[a] Reaction conditions: ArX: 2 mmol; olefin: 3 mmol; solvent: 6 mL; base: 3 mmol. [b] Bath temperature. [c] Yields of isolated products.
tivity than complex 3. For example, 1 mol-% of 7 gave a tions tested, and 2 mol-% of catalyst was sufficient to drive
99% yield of the coupling product of PhBr and p- the reactions to completion. These nickel complexes also
MeC6H4MgBr, while 1 mol-% of 3 under the same condi- proved to be good catalysts for deactivated aryl iodides. For
tions gave only 93% of the coupling product. The nickel example, 2 mol-% of 4b or 8b can catalyze the coupling of
complexes also catalyze the coupling of aryl iodides with p-MeOC6H4I with p-MeC6H4MgBr to give the cross-coup-
p-MeC6H4MgBr efficiently. However, the coupling of aryl ling product in excellent yield (Table 2, Entries 10 and 19).
bromides gave very low product yields. Complexes 4a, 4b, We also found that increased steric hindrance of the reac-
8a, and 8b show very similar catalytic activity in the reac- tion substrates led to a decrease of the product yields. For
Eur. J. Inorg. Chem. 2007, 4492–4499
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4495

Z.-X. Wang, Z.-Y. Chai
FULL PAPER
Table 2. Coupling of R1C6H4MgBr and aryl bromides or iodides catalyzed by complexes 3, 4, 7, and 8.[a]
Entry
R
R1
X
Catalyst
(mol-%)
T
Time
[h]
Yield
[%][c]
[°C][b]
1
2
3
4
5
H
H
o-Me
o-Me
p-Me
p-Me
o-Me
I
Br
Br
Br
Br
I
I
I
I
I
3 (0.8)
3 (1)
100
100
100
100
100
100
60
100
100
100
100
100
100
100
100
100
100
100
100
12
6
98
93
96
74
72
99
81
81
99
91
99
99
93
46
42
99
80
99
95
3 (1)
24
24
24
12
12
20
12
12
12
6
24
24
24
12
20
12
12
2,4,6-trimethyl
2,4,6-trimethyl
p-Me
3 (2)
3 (2)
2,4,6-trimethyl
6
H
H
o-Me
H
p-MeO
H
H
o-Me
o-Me
4a (2)
4a (2)
4a (2)
4b (2)
4b (2)
7 (0.5)
7 (1)
7[d]
8
p-Me
o-Me
p-Me
p-Me
p-Me
p-Me
o-Me
9
10
11
12
13
14
15
16
17
18
19
I
Br
Br
Br
Br
I
I
I
7 (1)
2,4,6-trimethyl
2,4,6-trimethyl
p-Me
7 (2)
2,4,6-trimethyl
H
7 (2)
8a (2)
8a (2)
8b (2)
8b (2)
o-Me
H
p-MeO
o-Me
p-Me
p-Me
I
[a] Reactions were carried out in a 1:1 mixture of thf/toluene unless otherwise indicated. [b] Bath temperature. [c] Yields of isolated
products. [d] Reaction was carried out in thf.
none (thf, Et2O and n-hexane), or CaH2 (CH2Cl2) and degassed
prior to use; dmf and dmp were dried with activated molecular
sieves, distilled under nitrogen, and degassed prior to use. CDCl3,
C5D5N, and C6D6 (Acros Organics) were degassed and stored over
either activated molecular sieves (CDCl3 and C5D5N) or Na/K al-
loy (C6D6). 2-Hydrazino-6-methylpyridine,[13] [(Ph3P)2Ni(Ar)-
Br],[14] and [PdCl2(PhCN)2][15] were prepared according to litera-
ture methods. Diisopropylamine was dried with NaOH, distilled
under nitrogen, and degassed prior to use. The aryl bromides used
for preparation of Grignard reagents, including p-MeC6H4Br, o-
MeC6H4Br, and α-bromonaphthalene, were distilled and degassed
prior to use. All other chemicals were obtained commercially and
used as received. NMR spectra were recorded with a Bruker av300
example, the reactions of 2,4,6-Me3C6H2MgBr with 2,4,6-
Me3C6H2Br or o-MeC6H4Br catalyzed by either 3 or 7
gave relatively low yields of coupling products (Table 2,
Entries 4, 5, 14 and 15). The reaction between o-
MeC6H4MgBr and o-MeC6H4I catalyzed by the nickel cat-
alysts 4a or 8a also gave lower yields of coupling product
than the reaction between p-MeC6H4MgBr and C6H5I
(Table 2, Entries 8 and 17), whereas the reaction of o-
MeC6H4MgBr and o-MeC6H4Br catalyzed by 3 or 7 seems
to be unaffected (Table 2, Entries 3 and 13).
1
spectrometer at ambient temperature. H and 13C NMR chemical
Conclusion
shifts are referenced to TMS or internal solvent resonances. Ele-
mental analyses were performed by the Analytical Center of the
We have synthesized and characterized nickel and palla-
dium complexes of the novel ligands [2-{OC(Ph)2CH2}-6- University of Science and Technology of China.
(3,5-Me2C3HN2)C5H3N]– and [2-{OC(Ph)=CH}-6-(3,5-
Preparations
Me2C3HN2)C5H3N]–. These complexes have square-planar
coordination geometries around the metal centers, as shown
2-(3,5-Dimethyl-1H-pyrazol-1-yl)-6-methylpyridine (1):[8] Pentane-
2,4-dione (0.48 g, 48 mmol) was added dropwise to a stirred solu-
tion of 2-hydrazino-6-methylpyridine (0.50 g, 40.6 mmol) in acetic
acid (10 mL) at room temperature and the resultant mixture re-
by their diamagnetism and single-crystal X-ray diffraction
results (for complexes 4b and 8a). The palladium complexes
exhibit good catalytic activity in the Heck and Kumada re-
actions. The nickel complexes also catalyze the coupling re- fluxed for 12 h. The acetic acid was then removed under reduced
pressure and the residue dissolved in CH2Cl2 (20 mL). This CH2Cl2
solution was washed twice with 10% Na2CO3 solution and then
dried with Na2SO4. The Na2SO4 was removed by filtration and the
solvent removed from the filtrate by rotary evaporation. The resi-
due was distilled under reduced pressure to give a colorless oil
action between aryl iodides and butyl acrylate or p-
MeC6H4MgBr.
Experimental Section
1
(0.71 g, 93%), b.p. 78–80 °C/0.1 Torr. H NMR (CDCl3): δ = 2.24
General Procedure: All experiments were performed under nitrogen
using standard Schlenk and vacuum-line techniques. Solvents were
distilled under nitrogen from sodium (toluene), sodium/benzophe-
(s, 3 H, Me), 2.46 (s, 3 H, Me), 2.55 (s, 3 H, Me), 5.90 (s, 1 H,
pyrazolyl), 6.93 (dd, J = 0.9, 7.4 Hz, 1 H, Py), 7.52–7.61 (m, 2 H,
Py) ppm.
4496
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 4492–4499

Palladium(II) and Nickel(II) Complexes of N,N,O-Chelate Ligands
[Li{2-[OC(Ph)2CH2]-6-(3,5-Me2C3HN2)C5H3N}] (2): A solution
49.05, 77.27, 113.98, 122.05, 122.38, 124.83, 125.14, 125.36, 126.40,
126.59, 126.87, 127.08, 128.08, 128.27, 128.88, 136.72, 137.72,
147.52, 155.62, 159.87 ppm. C31H29N3NiO (518.28): calcd. C 71.84,
H 5.64, N 8.11; found C 71.76, H 5.51, N 8.19. Single crystals of
complex 4a suitable for an X-ray diffraction analysis were obtained
by recrystallization of the sample from a mixture of thf and toluene.
of
2-(3,5-dimethyl-1H-pyrazol-1-yl)-6-methylpyridine
(0.48 g,
2.57 mmol) in thf (10 mL) was cooled to about –60 °C and a solu-
tion of LDA in Et2O [prepared from diisopropylamine (0.29 g,
2.8 mmol) and nBuLi (1.2 mL of a 2.5  solution in hexane,
3 mmol) in Et2O] was added with stirring. After stirring at –20 °C
for 20 min, the mixture was added dropwise to a solution of benzo-
phenone (0.50 g, 2.75 mmol) in thf (5 mL) at about –80 °C. The
resultant mixture was warmed to room temperature and stirred for
12 h. The solvent was then removed under vacuum and the residue
dissolved in toluene (10 mL). The solution was filtered and the fil-
trate was concentrated to about 2 mL. Diethyl ether (2 mL) was
added to the solution to give compound 2 (0.54 g, 56%) as colorless
[Ni(1-C10H7){2-{OC(Ph)2CH2}-6-(3,5-Me2C3HN2)C5H3N}] (4b): A
solution of 2 (0.08 g, 0.21 mmol) in thf (5 mL) was added to a
stirred solution of [(Ph3P)2Ni(naphthyl)Br] (0.17 g, 0.22 mmol) in
thf (10 mL) at about –80 °C. The mixture was warmed to room
temperature and stirred for 30 h, then the solvent was removed un-
der vacuum and the residue extracted with CH2Cl2. The extract
was filtered and then concentrated to dryness to give a red solid,
which was recrystallized from a mixture of CH2Cl2/hexane (1:1) to
afford red crystals (0.11 g, 83%), m.p. 171–173 °C. 1H NMR
(CDCl3): δ = 0.72 (s, 3 H, Me), 2.32 (s, MeC6H5), 2.38 (s, 3 H,
Me), 3.54 (d, J = 15.3 Hz, 1 H, CH), 3.81 (d, J = 15.3 Hz, 1 H,
CH), 5.63 (s, 1 H, pyrazolyl), 6.90–6.98 (m, 4 H, Ar), 7.06–7.15 (m,
6 H, Ar), 7.20–7.31 (m, 5 H, Ar), 7.37 (d, J = 7.2 Hz, 3 H, Ar),
7.60 (d, J = 7.2 Hz, 3 H, Ar), 7.70 (t, J = 8.1 Hz, 1 H, Ar), 8.00
(d, J = 6.9 Hz, 1 H, Ar), 9.29–9.32 (m, 1 H, Ar) ppm. 13C NMR
(CDCl3): δ = 13.86, 21.58, 49.32, 77.27, 107.16, 114.41, 122.19,
122.74, 123.70, 123.79, 123.92, 125.08, 125.24, 125.43, 125.96,
126.72, 127.42, 127.61, 128.02, 128.36, 129.17, 132.75, 133.54,
133.89, 138.02, 139.14, 140.23, 141.68, 151.77, 151.82, 156.11,
156.97, 160.38 ppm. C34H29N3NiO·0.8C7H8 (628.02): calcd. C
75.73, H 5.68, N 6.69; found C 75.75, H 5.75, N 6.67.
1
crystals, m.p. 227–228 °C. H NMR (C6D6): δ = 1.79 (s, 3 H, Me),
2.20 (s, 3 H, Me), 3.86 (s, 2 H, CH2), 5.41 (s, 1 H, pyrazolyl), 6.12
(d, J = 8.1 Hz, 1 H, Py), 6.23 (d, J = 7.5 Hz, 1 H, Py) 6.68 (t, J =
7.8 Hz, 1 H, Py), 6.84–6.87 (m, 2 H, Ph), 6.98 (br., 4 H, Ph), 7.65
(d, J = 7.2 Hz, 4 H, Ph) ppm. 13C NMR (C6D6): δ = 13.03, 14.01,
53.27, 81.62, 109.45, 122.48, 124.31, 126.84, 137.06, 138.04, 148.64,
151.04, 162.25 ppm. C24H22LiN3O (375.39): calcd. C 76.79, H 5.91,
N 11.19; found C 76.90, H 5.90, N 11.11.
2-[OC(Ph)2CH2]-6-(3,5-Me2C3HN2)C5H3N (2Ј): Hydrochloric acid
(2 , 20 mL) was added to a solution of 2 [prepared from 1 (0.72 g,
3.85 mmol), LDA, and Ph2CO according to the above procedure]
in thf (15 mL). The mixture was stirred for 1 h and then neutralized
with 2  NaOH. The aqueous layer was extracted twice with
CH2Cl2 (20 mL each time), and the combined organic layers were
dried with MgSO4. After concentration in vacuo, the product was
recrystallized from CH2Cl2/Et2O to give a white solid (1.0 g, 70.4%
based on the amount of 1), m.p. 156–157 °C. 1H NMR (CDCl3): δ
= 2.28 (s, 3 H, Me), 2.43 (s, 3 H, Me), 3.74 (s, 2 H, CH2), 5.98 (s,
1 H, pyrazolyl), 6.91 (dd, J = 2.4, 6 Hz, 1 H, Py), 7.12–7.27 (m, 7
H, Ph), 7.41–7.44 7.12–7.27 (m, 3 H, Ph), 7.50–7.66 (m, 2 H, Py)
ppm. 13C NMR (CDCl3): δ = 13.70, 14.22, 47.50, 78.36, 109.33,
114.74, 122.11, 126.32, 126.78, 128.13, 139.28, 141.11, 146.89,
150.26, 152.30, 157.22 ppm. C24H23N3O (369.46): calcd. C 78.02,
H 6.27, N 11.37; found C 77.79, H 6.24, N 11.22.
2-[6-(3,5-Dimethyl-1H-pyrazol-1-yl)pyridin-2-yl]-1-phenylethanone
(5): A solution of 2-(3,5-dimethyl-1H-pyrazol-1-yl)-6-methylpyr-
idine (0.48 g, 2.57 mmol) in thf (10 mL) was cooled to about –60 °C
and a solution of LDA in Et2O [prepared from diisopropylamine
(0.29 g, 2.8 mmol) and nBuLi (1.2 mL of a 2.5  solution in hexane,
3 mmol) in Et2O] was added with stirring. The mixture was stirred
at –20 °C for 20 min and was then added dropwise to PhCN
(0.30 g, 2.91 mmol) at about –80 °C. The resultant solution was
stirred at –20 °C for 30 min and at room temperature for 10 h. A
2  aqueous solution of H2SO4 (10 mL) was then added at 0 °C.
The mixture was stirred at room temperature for 10 h and then
neutralized with NaOH solution. The organic layer was separated
and the aqueous layer was extracted twice with diethyl ether
(20 mL each time). The combined ether solutions were dried with
Na2SO4, then the Na2SO4 was removed by filtration and the filtrate
was concentrated to give pale-yellow crystals (0.49 g, 66%), m.p.
[Pd(Cl){2-[OC(Ph)2CH2]-6-(3,5-Me2C3HN2)C5H3N}] (3): A solu-
tion of 2 (0.11 g, 0.29 mmol) in thf (5 mL) was added to a stirred
solution of [PdCl2(PhCN)2] (0.105 g, 0.27 mmol) in thf (10 mL) at
about –80 °C. The mixture was warmed to room temperature and
stirred for 10 h, then the solvent was removed under vacuum. The
residue was dissolved in CH2Cl2 and then filtered. Concentration
of the filtrate afforded pale-yellow crystals (0.11 g, 80%), m.p. 293–
295 °C. 1H NMR (CDCl3): δ = 2.54 (s, 3 H, Me), 2.59 (s, 3 H, Me),
1
80–81 °C. H NMR (CDCl3): δ = 2.19 (s, 3 H, Me), 2.41 (s, 3 H,
Me), 4.37 (s, 2 H, CH2), 5.86 (s, 1 H, pyrazolyl), 7.07 (t, J = 4.2 Hz,
3.97 (s, 2 H, CH2), 6.01 (s, 1 H, pyrazolyl), 7.03 (d, J = 7.8 Hz, 1 1 H, Ar), 7.32–7.50 (m, 3 H, Ar), 7.65 (d, J = 4.2 Hz, 2 H, Ar),
H, Py), 7.12–7.25 (m, 7 H, Ph+Py), 7.62 (d, J = 8.1 Hz, 4 H, Ph),
7.80 (t, J = 8.4 Hz, 1 H, Py) ppm. C24H22ClN3OPd (510.32): calcd.
C 56.49, H 4.35, N 8.23; found C 56.89, H 4.23, N 8.28.
7.94–7.97 (m, 2 H, Ar) ppm. 13C NMR (CDCl3): δ = 13.67, 14.64,
47.89, 109.05, 113.66, 120.71, 125.44, 128.43, 128.66, 128.85,
133.31, 136.59, 138.90, 141.68, 149.81, 153.28, 153.68, 196.73 ppm.
C18H17N3O (291.35): calcd. C 74.20, H 5.88, N 14.42; found C
74.28, H 5.58, N 14.26.
[Ni(o-MeC6H4){2-{OC(Ph)2CH2}-6-(3,5-Me2C3HN2)C5H3N}] (4a):
A solution of 2 (0.22 g, 0.59 mmol) in thf (5 mL) was added to a
stirred solution of [(Ph3P)2Ni(o-MeC6H4)Br] (0.44 g, 0.58 mmol) in
[Na{2-[OC(Ph)=CH]-6-(3,5-Me2C3HN2)C5H3N}] (6): A mixture of
thf (10 mL) at about –80 °C. The resultant solution was warmed 5 (0.60 g, 2.06 mmol) and NaH (0.08 g, 3.3 mmol) in thf (20 mL)
to room temperature and stirred for 30 h, then the solvent was re-
moved under vacuum and the residue was extracted with CH2Cl2.
The solvent was removed from the extract under reduced pressure
and the residual solid was recrystallized from thf to give red crystals
was refluxed for 12 h, then the mixture was filtered and the solvent
removed from the filtrate under vacuum. The residue was recrys-
tallized from a mixture of thf/hexane (1:1) to give pale-yellow crys-
tals (0.50 g, 77%), m.p. 245–247 °C. H NMR (C6D6): δ = 1.76 (s,
3 H, Me), 1.86 (s, 3 H, Me), 5.30 (s, 1 H, pyrazolyl), 5.67 (s, 1 H,
1
1
(0.28 g, 92%), m.p. 203–204 °C. H NMR (CDCl3): δ = 1.16 (s, 3
H, Me), 2.39 (s, 3 H, Me), 2.78 (s, 3 H, Me), 3.49 (d, J = 14.4 Hz,
CH), 5.92 (d, J = 7.5 Hz, 1 H, Py), 6.42–6.45 (m, 1 H, Py), 6.82–
1 H, CH), 3.68 (d, J = 14.4 Hz, 1 H, CH), 5.74 (s, 1 H, pyrazolyl), 7.16 (m, 4 H, Ph + Py), 7.99 (t, J = 7.8 Hz, 1 H, Py), 6.62–6.67
6.68–7.10 (m, 11 H, Ar), 7.37 (d, J = 6.3 Hz, 2 H, Ar), 7.61–7.70 (m, 4 H, Ph), 7.79 (d, J = 7.2 Hz, 2 H, Ph) ppm. 13C NMR (C6D6):
(m, 4 H, Ar) ppm. 13C NMR (CDCl3): δ = 13.50, 21.32, 24.97, δ = 13.57, 13.70, 95.16, 106.15, 108.68, 119.64, 127.02, 127.60,
Eur. J. Inorg. Chem. 2007, 4492–4499
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4497

Z.-X. Wang, Z.-Y. Chai
FULL PAPER
128.23, 135.73, 139.06, 147.35, 150.19, 150.37, 161.98, 173.33 ppm.
C18H16N3NaO (313.33): calcd. C 69.00, H 5.15, N 13.41; found C
69.32, H 5.11, N 13.75.
5.27, N 9.55; found C 68.42, H 5.42, N 9.49. Single crystals for X-
ray diffraction analysis were obtained by recrystallization of the
sample from a mixture of thf and benzene.
[Pd(Cl){2-{OC(Ph)=CH}-6-(3,5-Me2C3HN2)C5H3N}] (7): A solu-
tion of 6 (0.13 g, 0.42 mmol) in thf (5 mL) was added to a stirred
solution of [PdCl2(PhCN)2] (0.13 g, 0.34 mmol) in thf (10 mL) at
about –80 °C. The mixture was stirred at room temperature over-
night, then the solvent was removed under vacuum. The residue
was dissolved in CH2Cl2 and then filtered. Concentration of the
filtrate afforded red crystals of 7 (0.10 g, 68%), m.p. 293–295 °C.
1H NMR (CDCl3): δ = 2.58 (s, 3 H, Me), 2.62 (s, 3 H, Me), 5.93
(s, 1 H, CH), 6.04 (s, 1 H, pyrazolyl), 6.86 (d, J = 8.1 Hz, 1 H, Py),
6.91 (d, J = 8.1 Hz, 1 H, Py), 7.27–7.32 (m, 3 H, Ph), 7.53 (t, J =
8.1 Hz, 1 H, Py), 7.80–7.83 (m, 2 H, Ph) ppm. 13C NMR
(CDCl3+C5D5N): δ = 14.19, 14.35, 77.37, 112.15, 118.83, 119.16,
119.48, 121.46, 122.84, 124.39, 126.02, 127.26, 127.29, 128.07,
134.95, 147.42, 147.78, 157.20 ppm. C18H16ClN3OPd (432.21):
calcd. C 50.02, H 3.73, N 9.72; found C 50.00, H 3.64, N 9.64.
[Ni(1-C10H7){2-[OC(Ph)=CH]-6-(3,5-Me2C3HN2)C5H3N}] (8b): A
solution of 5 (0.17 g, 0.54 mmol) in thf (5 mL) was added to a
stirred solution of [(PPh3)2Ni(naphthyl)Br] (0.40 g, 0.51 mmol) in
thf (10 mL) at about –80 °C. The resultant solution was warmed
to room temperature and stirred for 30 h, then the solvent was re-
moved under vacuum and the residue dissolved in CH2Cl2. The
mixture was filtered and the filtrate was concentrated to give red
1
crystals of 8b (0.17 g, 71%), m.p. 239–240 °C. H NMR (CDCl3):
δ = 0.84 (s, 3 H, Me), 2.48 (s, 3 H, Me), 5.76 (s, 1 H, pyrazolyl),
6.08 (s, 1 H, CH), 6.75 (d, J = 7.8 Hz, 1 H, Py), 6.84 (d, J = 8.1 Hz,
1 H, Py), 7.01–7.15 (m, 5 H, Ar), 7.27–7.43 (m, 5 H, Ar), 7.53 (t,
J = 8.1 Hz, 1 H, Py), 7.58–7.62 (m, 1 H, Ar), 7.89 (d, J = 6.6 Hz,
1 H, Ar), 9.66 (d, J = 7.8 Hz, 1 H, Ar) ppm. 13C NMR (CDCl3): δ
= 14.39, 15.27, 93.11, 99.56, 113.89, 119.66, 122.72, 123.56, 123.77,
124.23, 126.59, 127.82, 127.86, 128.38, 128.70, 129.19, 132.86,
133.16, 133.88, 136.17, 139.77, 140.18, 141.97, 146.45, 153.84,
155.16, 155.32, 170.23 ppm. C28H23N3NiO (476.20): calcd. C 70.62,
H 4.87, N 8.82; found C 70.46, H 4.81, N 9.07.
[Ni(o-MeC6H4){2-[OC(Ph)=CH]-6-(3,5-Me2C3HN2)C5H3N}] (8a):
A solution of 6 (0.15 g, 0.48 mmol) in thf (5 mL) was added to a
stirred solution of [(PPh3)2Ni(o-MeC6H4)Br] (0.33 g, 0.43 mmol) in
thf (10 mL) at about –80 °C. The solution was warmed to room
temperature and stirred for 30 h, then the solvent was removed un- Crystal Structure Determination: Single crystals were mounted in
der vacuum and the residue extracted with CH2Cl2. The solvent
was removed from the extract under vacuum and the residual solid
was recrystallized from a 1:1 mixture of thf/toluene to afford brown
crystals of 8a (0.16 g, 85%), m.p. 247–248 °C. H NMR (CDCl3):
δ = 1.17 (s, 3 H, Me), 2.37 (s, 3 H, Me), 3.00 (s, 3 H, Me), 5.75 (s,
Lindemann capillaries under nitrogen. Diffraction data were col-
lected with a Siemens CCD area detector with graphite-monochro-
mated Mo-Kα radiation (λ = 0.71073 Å). The structure was solved
by direct methods using SHELXS-97[16] and refined against F2 by
full-matrix least squares using SHELXL-97.[17] Hydrogen atoms
1
1 H, pyrazolyl), 5.98 (s, 1 H, CH), 6.63 (d, J = 7.8 Hz, Py), 6.73– were placed in calculated positions. Crystal data and experimental
6.75 (m, 4 H, C6H4+Py), 7.11–7.15 (m, 3 H, Ph), 7.45 (t, J = details of the structure determinations are listed in Table 3. CCDC-
8.1 Hz, 1 H, Py), 7.51–7.54 (m, 2 H, Ph), 7.67–7.71 (m, 1 H, C6H4) 641763 and -641764 (for 4b·C7H8 and 8a·0.5C6H6, respectively)
ppm. 13C NMR (CDCl3): δ = 14.13, 15.19, 25.16, 92.96, 99.66, contain the supplementary crystallographic data for this paper.
113.76, 119.46, 122.67, 122.74, 122.47, 126.47, 127.89, 128.64,
136.05, 136.46, 139.93, 140.12, 144.27, 146.15, 152.67, 153.56,
155.04, 169.88 ppm. C25H23N3NiO (440.16): calcd. C 68.22, H
These data can be obtained free of charge from The Cambridge
Crystallographic
data_request/cif.
Data
Centre
via
www.ccdc.cam.ac.uk/
Table 3. Summary of crystal data for complexes 4b and 8a.
4b·C7H8
8a·0.5C6H6
Empirical formula
Formula mass
C41H37N3NiO
646.45
C28H26N3NiO
479.23
Crystal system
Space group
monoclinic
P21/n
monoclinic
C2/c
a [Å]
b [Å]
c [Å]
15.609(2)
11.1736(15)
19.144(3)
95.792(2)
3321.7(8)
4
20.171(3)
13.841(2)
18.560(3)
96.873(2)
5144.5(14)
8
β [°]
V [Å3]
Z
T [K]
294(2)
1.293
298(2)
1.237
Dcalcd. [gcm–3]
F(000)
1360
0.621
2008
0.777
µ [mm–1]
θ range for data collection [°]
Absorption correction
No. of reflections collected
No. of independent reflections (Rint
No. of data/restraints/parameters
Goodness of fit on F2
Final R indices[a] [I Ͼ 2σ(I)]
1.77–26.40
semiempirical from equivalents
18266
6767 (Rint = 0.0493)
6767/92/457
1.000
R1 = 0.0464,
wR2 = 0.0962
R1 = 0.1007,
wR2 = 0.1202
0.328/–0.239
2.03–25.01
semiempirical from equivalents
12474
4477 (Rint = 0.0531)
4477/102/325
1.001
R1 = 0.0695,
wR2 = 0.1775
R1 = 0.1352,
wR2 = 0.2258
0.571/–0.589
)
R indices (all data)
Largest diff peak/hole [eÅ–3]
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|; wR2 = [Σw(Fo – Fc ) /Σw(Fo4)]1/2
.
2
2 2
4498
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 4492–4499

Palladium(II) and Nickel(II) Complexes of N,N,O-Chelate Ligands
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3957; h) A. Fürstner, H. Krause, C. W. Lehmann, R. Martin,
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charged with aryl halide (2 mmol), butyl acrylate or styrene
(3 mmol), a base (3 mmol), the pre-catalyst, and solvent (6 mL)
and the mixture was stirred at the appropriate temperature for the
specified period of time. The mixture was then cooled to room
temperature and quenched with a 1  aqueous solution of hydro-
chloric acid (3 mL). The aqueous phase was extracted with CH2Cl2
(3ϫ5 mL), then the combined organic layers were washed with
water (10 mL) and dried with Na2SO4. The NaSO4 was removed
by filtration and the filtrate was concentrated. The residue was
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charged with aryl halide (2 mmol), pre-catalyst, solvent (4 mL), and
a magnetic stir bar, then a thf solution of p-MeC6H4MgBr (pre-
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specified period of time. After the mixture had been cooled to room
temperature, the reaction was quenched with water. The aqueous
phase was extracted with CH2Cl2 (3ϫ5 mL) and the combined or-
ganic layers were dried with MgSO4. The MgSO4 was removed by
filtration and the filtrate was concentrated. The residue was puri-
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Acknowledgments
We thank the Natural Science Foundation of Anhui Province (pro-
ject code: 070416238) for support.
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Received: March 28, 2007
Published Online: July 31, 2007
Eur. J. Inorg. Chem. 2007, 4492–4499
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4499