Synthesis and characterization of phospha-palladacycles and their catalytic properties in the olefination of chloro- and bromoarenes

Article abstract of DOI:10.1016/j.jorganchem.2005.03.052

Acetylacetonates of phospha-palladacycles are new catalysts in the Heck coupling of aryl chlorides and bromides with styrene. Turnover numbers (TON) of much higher than 300,000 and product yields up to 99% are obtained.

Full text of DOI:10.1016/j.jorganchem.2005.03.052

Journal of Organometallic Chemistry 690 (2005) 3193–3201
www.elsevier.com/locate/jorganchem
Synthesis and characterization of phospha-palladacycles
and their catalytic properties in the olefination
of chloro- and bromoarenes
a
Guido D. Frey , Claus-Peter Reisinger , Eberhardt Herdtweck ,
b
a
a,
*
Wolfgang A. Herrmann
a
Department Chemie, Lehrstuhl fu¨r Anorganische Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstraße4, D-85747 Garching, Germany
b
EXATEC GmbH & Co. KG, Friedrich-Ebert-Straße, D-51429 Bergisch Gladbach, Germany
Received 28 December 2004; accepted 7 March 2005
Available online 23 May 2005
Abstract
Acetylacetonates of phospha-palladacycles are new catalysts in the Heck coupling of aryl chlorides and bromides with styrene.
Turnover numbers (TON) of much higher than 300,000 and product yields up to 99% are obtained.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Catalysis; CC-coupling; Heck reaction; Palladacycles; Palladium; Chloroarenes
1. Introduction
TON in the Heck coupling reaction of iodobenzene with
styrene [7,8]. However, iodobenzene is very expensive
and not at all a candidate in industry as a chemical feed-
stock. We logically developed routes to catalytically
activate the industrially relevant bromo- and particu-
larly chloroarenes.
Most of our work on palladacycle catalytic systems
has been focused on the arylation of olefines with aryl
halides – generally referred as the Mizoroki–Heck reac-
tion [1]. Because of its enormous synthetic potential for
generating carbon–carbon bonds and its tolerance to-
wards a wide range of functional groups, this reaction
has received considerable attention [2]. Catalysts based
upon cyclopalladated tris(o-tolyl)phosphine were first
characterized by Shaw [3], Aleya [4], and Heck [5], and
were intensely investigated in our group [6]. They prom-
ised to become excellent catalysts in organic synthesis.
It was repeatedly mentioned that acetylacetonate
substituted palladacycles (1,2) (Fig. 1) show very high
2. Synthesis and properties of the catalysts
The new acetylacetonate palladacycles were prepared
by treatment of the acetate bridged palladacycles 3 [6]
with 2,4-pentandione (Hacac) in dichloromethane to af-
ford the acetylacetonate products 5a–5e in nearly quan-
titative yield according to Scheme 1.
Another possibility to achieve the catalysts 5a–5e, is
to start from the halide-bridged palladacycles 4a–4e in
a sodiumhydroxide/toluene/water mixture.
*
Corresponding author. Tel.: +49 89 289 13080; fax: +49 89 289
13473.
By reaction of phosphane 6 with Pd(OAc)2 at room
temperature in toluene for 12 h, the expected dinuclear
E-mail address: lit@arthur.anorg.chemie.tu-muenchen.de (W.A.
Herrmann).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.03.052

3194
G.D. Frey et al. / Journal of Organometallic Chemistry 690 (2005) 3193–3201
chemistry [9]. In particular, palladium-catalyzed reac-
R1
R1
PR2
R2
P
Pd
tions have proven to be most versatile in this reaction.
Aryl olefines are commonly employed building blocks
in natural products as well as in fine chemicals synthesis
making the Mizoroki–Heck reaction one of the most
important modern synthetic methods [2b].
The catalysts 5a–5e and 8 are quite equal for the
Heck coupling of bromoaryls with styrene to stilbenes
(Table 1). A lower reactivity is observed for catalyst 8
in comparison to the other catalysts for the reaction of
chloroaryls with styrene. The lower reactivity of naph-
thyl-substituted palladacycles was also observed by
Shaw et al. [7] at the example of iodobenzene/styrene.
The TONs of the catalysts (5a–5e) in these reactions
are as high as the reported ones [7]. However, it is
now possible with the new acetylacetonato-palladacycles
to couple the relatively little reactive, cheaper bromo-
and chloroaryls with styrene.
O
O
R1
Pd
O
O
R1
1a R = o-tolyl, R1 = CH3
1b R = o-tolyl, R1 = CF3
2a R = naphthyl, R1 = CH3
2b R = naphthyl, R1 = CF3
Fig. 1. Acetylacetonate catalysts.
metallacycle 7 can be obtained in 88% yield. Compound
1
7 shows broad H NMR signals at 25 ꢁC. By treating 7
with 2,4-pentandione in dichlormethane we received the
mononuclear acetylacetonato complex 8 (see Scheme 2).
This product shows very sharp NMR signals at 25 ꢁC.
Such broad and sharp NMR spectra were similarly
found at other palladacycles [7,8b].
Screening for the optimum base showed most inor-
ganic bases are equally capable of furnishing stilbene.
Differences in TON were generally small. The very
cheap NaOAc showed very good results. Palladium
black precipitation was not detected when the bases
NaOAc, Na2CO3, Cs2CO3, K2CO3 were used. Stronger
3. Catalysis
The formation of CC-bonds between arenes and ole-
fines is an important reaction in modern synthetic arene
Ac
R1
n-(C4H9)4NCl
+ Hacac
O
1
Pd
/
2
2
P
R1
R2 R3
3a - e
R1
R1
Cl
O
O
1
+ Hacac
Pd
/
2
Pd
2
P
P
toluene/H2O
NaOH
R1
R2 R3
R1
R2 R3
4a - e
5a - e
5a R1 = CH3 R2 = mesityl
5b R1 = H R2 = o-tolyl
5c R1 = H R2 = o-tolyl
5d R1 = H R2 = t-butyl
R3 = mesityl
R3 = cyclohexyl
R3 = t-butyl
R3 = t-butyl
5e R1 = H R2 = cyclohexyl R3 = cyclohexyl
Scheme 1. Synthesis of acetylacetonate-palladacycles (5a–5e).
Ac
O
O
Pd(OAc)2
toluene
+ Hacac
- HOAc
Pd
Pd
P
2
P
Ph
P
Ph
O
Ph
Ph
6
8
7
Scheme 2. Preparation of complexes 7 and 8.

G.D. Frey et al. / Journal of Organometallic Chemistry 690 (2005) 3193–3201
3195
Table 1
Comparison of the catalysts 5a–5e and 8 in Heck olefination of aryl halides with styrene
X
cat. [Pd]a
+
+ HX
R
R
Entry
R
X
Catalyst
mol% Catalyst
t (h)
Conversion (%)
Yield [%]b
TONc
1
2
COCH3
COCH3
COCH3
COCH3
COCH3
COCH3
H
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Cl
Cl
Cl
Cl
Cl
Cl
5a
5b
5c
5d
5e
8
0.1
0.1
0.1
0.1
0.1
0.1
1
18
18
18
18
18
18
18
18
18
18
18
19
18
23
18
18
18
18
18
18
100
100
100
100
100
100
84
95
90
96
93
81
91
95
95
>99
>99
98
80
94
86
94
90
79
81
55
51
8
910
950
950
990
990
980
80
3
4
5
6
7
5a
5b
5c
5d
5e
8
8
H
1
95
86
9
H
1
10
11
12
13
14
15
16
17
18
19
20
a
H
1
94
90
H
1
H
0.1
0.1
0.033
0.1
0.1
0.1
0.1
0.1
0.1
790
810
1410
510
80
OCH3
OCH3
COCH3
COCH3
COCH3
COCH3
COCH3
COCH3
5c
5d
5a
5b
5c
5d
5e
8
82
59
56
9
53
50
34
38
6
510
340
380
60
39
41
8
One equivalent of aryl halide, 1.5 equivalents of styrene, 1.5 equivalents of NaOAc, dimethylacetamide (DMAc), T = 130 ꢁC.
GC – yields using diethyleneglycol-di-n-butyl ether as the internal standard.
(mol product)/(mol Pd).
b
c
bases like Ca(OH)2 and especially KOH rendered useless
of 430 [mol product per mol 5d per hour]. Using bromo-
anisole as a reactant a decreased yield was obtained by
changing the solvent from NMP (65% yield) to DMAc
(55% yield).
With the new palladacycles it is also possible to cou-
ple non activated chloroarenes with styrene (see Table
4).
The acetylacetonato-palladacycle 5d shows a very
high TON of up to 329,000 [mol product per mol 5d]
with the activated bromoacetophenone, even with the
non activated bromobenzene turn over numbers of up
to 265,000 could be achieved. With chlorobenzene a dra-
matic decrease of the TON was recognized but a TON
of 3500 for a non activated chloroaryl is still one of
the best results ever published in literature for phos-
pha-palladacycles (see Table 5). The range of the cata-
lytic turn over frequencies (TOF) lies in the range of
4700–50 [mol product per mol 5d per hour]. All determi-
nations were carried out without the co-catalyst
NBu4Br; adding this co-catalyst even higher TON and
TOF can be expected (cf. Table 2).
as they lead to small decomposition of the catalyst and
additionally of NBu4Br in a Hofmann-type elimination
and less yield [10]. We ascribe the indifference in TON
towards the nature of the base to the good solubility
of all bases in presence of NBu4Br at 130 ꢁC and by
using the very polar solvent dimethylacetamide
(DMAc). Thus, any base which is capable of reductively
eliminating HX from the hydrido palladium species
HPd(L)2X can be used. As a result for coupling of chlo-
roarenes with styrene, Cs2CO3 can be replaced by much
more active and economic bases like NaOAc or
Na2CO3. The addition of the co-catalyst NBu4Br per-
forms a higher TON of the catalysts. This result has
been reported for palladacycles like 3 in our group [6].
It has long been known that in the Heck reaction very
polar solvents such as dimethylacetamide (DMAc) and
N-methyl-2-pyrrolidinone (NMP) perform the best re-
sults. NMP gives better results for deactivated aryl ha-
lides than the cheaper DMAc (Table 3). The highly
polar solvent sulfolane results in no product and in the
decomposition of the palladacycle. Hexamethylphos-
phoramide (HMPA) gave acceptable results in the catal-
ysis, but is highly toxic and expensive and therefore not
the first choice for a solvent.
4. Single crystal X-ray structure determination of
compounds 5e and 7
In Fig. 2 the 4-bromoacetophenone was converted
completely after 420 min to the according product [(E/
Z)-4-acetylstilbene], with a TOF over the whole time
Crystal data and details of the structure determination
are presented in Table 6. Suitable single crystals for the

3196
G.D. Frey et al. / Journal of Organometallic Chemistry 690 (2005) 3193–3201
Table 2
The influence of base and co-catalyst in the Heck reactiona
Entry
R
X
Base
Co-catalyst
Catalyst
mol% Catalyst
t (h)
Conversion (%)
Yield (%)b
TONc
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
a
C(O)CH3
C(O)CH3
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Cl
Cl
Cl
Cl
Cl
NaOAc
NaOAc
Cs2CO3
Na2CO3
Ca(OH)2
K2CO3
NaOAc
KOH
NBu4 Br
–
7
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
1
14
14
14
19
19
19
19
19
19
18
19
19
19
19
19
19
18
18
18
18
18
18
18
23
14
14
14
100
100
20
99
97
96
93
82
77
96
98
96
93
95
81
34
82
57
13
85
69
68
39
2
>99
85
10
98
96
95
92
82
75
94
97
95
91
88
80
34
81
53
9
990
850
100
980
960
950
920
820
750
94
7
C(O)CH3
H
–
NBu4Br
7
5d
5d
5d
5d
5d
5d
5d
8
H
NBu4Br
NBu4Br
H
H
NBu4Br
NBu4Br
H
H
CsCO3
NaOAc
K2CO3
Na2CO3
KOH
NBu4Br
–
H
H
–
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.01
0.1
0.1
0.033
0.1
0.1
0.1
970
950
910
880
800
340
810
530
88
H
–
8
H
–
8
H
Ca(OH)2
NaOAc
CsCO3
NaOAc
K2CO3
CsCO3
NaOAc
NaOAc
NaOAc
NaOAc
Ca(OH)2
Cs2CO3
NaOAc
Cs2CO3
–
8
H
–
8
H
–
8
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
COCH3
COCH3
COCH3
H
–
5c
5c
5c
7
–
–
NBu4Br
84
53
67
34
1.8
29
19
1
840
5300
670
340
54
NBu4Br
–
7
7
–
5d
5d
7
–
–
31
25
2
290
190
10
NBu4Br
NBu4Br
7
H
7
One equivalent of aryl halide, 1.5 equivalents of styrene, 1.5 equivalents of base, 20 mol% co-catalyst, dimethylacetamide (DMAc), T = 130 ꢁC.
GC – yields using diethyleneglycol-di-n-butyl ether as the internal standard.
(mol product)/(mol Pd).
b
c
Table 3
Influence of the solvent in the Heck coupling reaction of aryl halides with styrenea
Entry
R
X
Base
Solvent
Catalyst
mol% Catalyst
t (h)
Conversion (%)
Yield (%)b
TONc
48
49
50
51
52
53
54
55
56
57
a
COCH3
COCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
NaOAc
NaOAc
NaOAc
NaOAc
NaOAc
K2CO3
CsCO3
NaOAc
NaOAc
NaOAc
DMAc
NMP
5d
5d
5c
5c
5c
5c
5c
5c
5d
5d
0.1
18
23
18
18
18
18
18
18
23
23
100
100
85
86
82
58
14
0
>99
>99
85
84
81
53
9
990
3030
850
840
810
530
88
0.033
0.1
0.1
HMPA
NMP
DMAc
DMAc
DMAc
sulfolane
NMP
0.1
0.1
0.1
0.1
0
0
0.033
0.033
74
59
65
55
1970
1660
DMAc
One equivalent of aryl halide, 1.5 equivalents of styrene, 1.5 equivalents of base, T = 130 ꢁC.
GC – yields using diethyleneglycol-di-n-butyl ether as the internal standard.
(mol product)/(mol Pd).
b
c
X-ray diffraction study were grown from dichlormethane
squares refinement of 4435 (9918) reflections. Data collec-
tion were performed at 123 (123) K (OXFORD CRYO-
SYSTEMS) within a h-range of 1.89ꢁ < h < 25.36ꢁ (1.95ꢁ
< h < 25.34ꢁ). Measured with nine (four) data sets in rota-
tion scan modus with Du/Dx = 1.0ꢁ (1.0ꢁ). A total num-
ber of 51,741 (67,268) intensities were integrated. Raw
data were corrected for Lorentz, polarization, and, aris-
ing from the scaling procedure, for latent decay and
absorption effects. After merging [Rint = 0.038 (0.040)] a
sum of 4234 (9680) (all data) and 3961 (7912) [I > 2r(I)],
by slow evaporation of the solvent at ambient tempera-
ture. A clear colorless fragment (light yellow prism) was
stored under perfluorinated ether, transferred in a Linde-
mann capillary, fixed, and sealed. Preliminary examina-
tion and data collection were carried out on an area
detecting system (NONIUS, MACH3, j-CCD) at the
windowofarotatinganode(NONIUS, FR951)andgraph-
˚
ite monochromated Mo Ka radiation (k = 0.71073 A). The
unit cell parameters were obtained by full-matrix least-

G.D. Frey et al. / Journal of Organometallic Chemistry 690 (2005) 3193–3201
3197
100
90
80
70
60
50
40
30
20
10
0
49
56
57
0
200
400
600
800
1000
1200
1400
time [min]
Fig. 2. Comparison of different reaction conditions and dependence of the solvent in the Heck reaction: yield of the product against time. Reaction
conditions: aryl halide (1 mmol), styrene (1.5 mmol), NaOAc (1.5 mmol), T = 130 ꢁC, catalyst 5d (numbers see entry in Table 4).
respectively, remained and all data were used. The struc-
tures were solved by a combination of direct methods and
difference Fourier syntheses. All non-hydrogen atoms
were refined with anisotropic displacement parameters.
5e: All hydrogen atoms were found and refined with indi-
vidual isotropic displacement parameters. 7: All hydro-
gen atoms were placed in ideal positions (riding model).
Table 6
Crystallographic data for complex 5e and 7
Table 4
Heck olefination of chlorobenzene with styrene and the catalysts 5a–5e
and 8
5e
7
Formula
Fw
C24H35O2PPd
492.91
C50H42O4P2Pd2
981.62
Cl
cat. [Pd]a
+
+ HCl
Color/habit
Crystal dimensions
(mm3)
Colorless/fragment
0.36 · 0.51 · 0.56
Light yellow/prism
0.38 · 0.43 · 0.76
TONc
Crystal system
Space group
Monoclinic
P21/c (no. 14)
9.6461(1)
13.6063(1)
17.6048(1)
90.1833(4)
2310.58(3)
4
Monoclinic
P21/n (no. 14)
11.4471(1)
23.1637(1)
20.1354(2)
97.2331(3)
5296.56(7)
4
Entry
Catalyst
mol% Catalyst
Conversion
(%)
Yield
(%)b
˚
a (A)
58
59
60
61
62
63
a
5a
5b
5c
5d
5e
8
0.1
0.1
0.1
0.1
0.1
0.1
17
14
2
2
20
20
18
15
10
10
˚
b (A)
2
˚
c (A)
1.8
1.5
1
b (ꢁ)
16
14
9
3
˚
V (A )
Z
T (K)
1
123
1.417
123
1.231
Dcalc (g cmꢀ3
)
One equivalent of chlorobenzene, 1.5 equivalents of styrene, 1.5
l (mmꢀ1
F(000)
)
0.889
1024
0.776
1984
equivalents of Ca(OH)2, N-methylpyrrolidone, T = 130 ꢁC, t = 22 h.
GC – yields using diethyleneglycol-di-n-butyl ether as the internal
b
standard.
c
h Range (ꢁ)
1.89–25.36
11, 16, 21
51,741
1.95–25.34
13, 27, 24
67,268
(mol product)/(mol Pd).
Index ranges (h,k,l)
No. of reflections
collected
No. of independent
reflections/Rint
4234/0.038
3961
9680/0.040
7912
Table 5
Determination of turn over numbers in the Heck olefination of
different aryl halides with styrene and palladacycle 5d as catalysta
No. of observed
reflections (I > 2r(I))
No. of data/restraints/
parameters
R1/wR2 (I > 2r(I))[a]
R1/wR2 (all data)[a]
GOF (on F2)[a]
Entry
R
X
mol% Catalyst
Yield (%)b
TONc
4234/0/394
9680/0/527
64
65
66
a
4-COCH3
4-H
4-H
Br
Br
Cl
0.000161
0.000242
0.00241
53
64
8
329000
265000
3500
0.0204/0.0468
0.0228/0.0477
1.088
0.0334/0.0887
0.0420/0.0919
1.074
One equivalent of aryl halide, 1.5 equivalents of styrene, 1.5
Largest differential peak
ꢀ3
+0.62/ꢀ0.39
+1.15/ꢀ0.65
equivalents of NaOAc, DMAc, T = 130 ꢁC, t = 70 h.
GC – yields using diethyleneglycol-di-n-butyl ether as the internal
˚
and hole (e A
)
b
P
P
P
P
2
2
1=2
a
R1 = (iFoj ꢀ jFci)/ jFoj; wR2¼f ½wðF 2o ꢀF c2Þ ꢁ= ½wðF o2Þ ꢁg
;
standard.
c
P
2
1=2
GOF¼f ½wðF 2o ꢀF 2cÞ ꢁ=ðnꢀpÞg
.
(mol product)/(mol Pd).

3198
G.D. Frey et al. / Journal of Organometallic Chemistry 690 (2005) 3193–3201
electron density maps showed no remarkable features.
Neutral atom scattering factors for all atoms and anoma-
lous dispersion corrections for the non-hydrogen atoms
were taken from International Tables for Crystallogra-
phy. All calculations were performed on an Intel Pentium
II PC, with the STRUX-V system, including the programs
PLATON, SIR-92, and SHELXL-97 [11]. 5e: Small extinction ef-
fects were corrected with the SHELXL-97 procedure
[e = 0.0015(1)]. 7: An unresolvable disorder of solvent
molecules was cured effectively with the PLATON CALC
SQUEEZE procedure. Complexes 5e and 7 are shown in
Figs. 3 and 4.
In the solid state of complex 5e the two oxygen atoms
of the acetylacetonate group do not have equal bond
lengths to the palladium. The oxygen coordinated trans
to the carbon shows a longer bond length (211.6(1) pm)
than the oxygen coordinated trans to the phosphine
(208.1(1) pm), because of the donating effect of this
carbanion. This behaviour was first observed in complex
1a (211.2, 207.8 pm) for these complexes in our group
[8a]. Also results of a crystallographic analysis of com-
plex 5d showed the same characteristics 211.1(4) and
208.9(4) pm [12].
Fig. 3. ORTEP style plot of the solid state structure of compound 5e.
Thermal ellipsoids are drawn at the 50% probability level. The
˚
hydrogen atoms are omitted for clarity. Selected bond lengths (A) and
bond angles (ꢁ): Pd–P 2.1983(4), Pd–O1 2.116(1), Pd–O2 2.081(1), Pd–
C17 2.030(2); P–Pd–O1 97.69(4), P–Pd–O2 170.78(4), P–Pd–C17
84.06(6), O1–Pd–O2 89.96(5), O1–Pd–C17 176.24(7), O2–Pd–C17
88.61(7), Pd–P–C11 106.01(6), Pd–P–C21 113.72(6), Pd–P–C31
114.71(6), C11–P–C21 107.86(8), C11–P–C31 105.99(8), C21–P–C31
108.05(8).
5. Conclusion
Acetylacetonate complexes of palladacycles show
excellent air and thermal stability even at elevated tem-
peratures. They are very active catalysts for the Mizor-
oki–Heck reaction. The structural identity was settled
by single crystal X-ray diffraction studies. Both activity
and stability of the catalytically active species can be
triggered by the new catalysts in the Mizoroki–Heck
reaction. It is now proven that these catalysts are suc-
cessfully applicable to arylbromides and -chlorides in
the coupling with styrene.
6. Experimental
Fig. 4. ORTEP style plot of the solid state structure of compound 7.
Thermal ellipsoids are drawn at the 50% probability level. The
6.1. General comments
˚
hydrogen atoms are omitted for clarity. Selected bond lengths (A) and
bond angles (ꢁ): Pd1–P1 2.1937(7), Pd1–O1 2.107(2), Pd1–O2 2.149(2),
Pd1–C12 1.989(3), Pd2–P2 2.1960(7), Pd2–O3 2.104(2), Pd2–O4
2.125(2), Pd2–C35 1.986(3); P1–Pd1–O1 171.53(6), P1–Pd1–O2
93.90(6), P1–Pd1–C12 83.45(7), O1–Pd1–O2 87.13(9), O1–Pd1–C12
94.2(1), O2–Pd1–C12 170.5(1), P2–Pd2–O3 167.81(7), P2–Pd2–O4
91.83(7), P2–Pd2–C35 83.48(8), O3–Pd2–O4 89.02(9), O3–Pd2–C35
93.7(1), O4–Pd2–C35 170.1(1), Pd1–P1–C5 105.80(8), Pd1–P1–C16
111.01(9), Pd1–P1–C22 116.11(9), C5–P1–C16 109.6(1), C5–P1–C22
107.4(1), C16–P1–C22 106.8(1), Pd2–P2–C28 105.62(8), Pd2–P2–C39
110.75(9), Pd2–P2–C45 115.65(9), C28–P2–C39 108.9(1), C28–P2–C45
108.5(1), C39–P2–C45 107.2(1).
(2-Methylnaphthyl)diphenylphosphane 6 [13] and the
dimeric palladacycle-precursors (3a–3e) were prepared
according to reported procedures [6b].
1H, 13C and31P NMR spectra were recorded on a
JEOL-JMX-GX 270 or 400 MHz spectrometer at room
1
temperature and referenced to the residual H and 13C
signals of the solvents or 85% H3PO4 as an external
standard (31P). NMR multiplicities are abbreviated as
follows: s = singlet, d = doublet, t = triplet, m = multi-
plet, br. = broad signal. Coupling constants J are given
in Hertz. GC–MS spectra were measured on a Hew-
lett–Packard gas chromatograph GC 5890 A equipped
with a mass selective detector MS 5970 B. Quantitative
analyses were performed on a Hewlett–Packard GC
Full-matrix least-squares refinements with 394 (527)
parameters were carried out by minimizing
P
2
wðF 2o ꢀ F 2cÞ with the SHELXL-97 weighting scheme
and stopped at shift/err <0.001 (0.001). The final residual

G.D. Frey et al. / Journal of Organometallic Chemistry 690 (2005) 3193–3201
3199
5890 A equipped with a flame ionization detector (GC/
FID).
Elemental analyses were carried out by the Microan-
alytical Laboratory at the TU Munchen. Mass spectra
¨
were performed at the TU Munchen Mass Spectrometry
¨
CDCl3): d = 188.2 (s, COacac), 186.6 (s, COacac), 158.9
(d, CAryl, JPC = 29 Hz), 143.6 (d, CAryl, JPC = 12 Hz),
134.9 (s, CAryl), 134.4 (s, CAryl), 132.5 (d, CAryl
JPC = 9 Hz), 131.8 (d, CAryl, JPC = 5 Hz), 131.2 (d, CAryl
JPC = 2 Hz), 131.0 (s, CAryl), 130.8 (d, CAryl
,
,
,
Laboratory on a Finnigan MAT 90 spectrometer using
the CI or FAB technique.
JPC = 2 Hz), 129.3 (s, CAryl), 128.7 (d, CAryl, JPC =
9 Hz), 125.9 (d, CAryl, JPC = 7 Hz), 99.7 (s, CHacac),
37.2 (s, CH3,acac), 36.9 (s, CH3,acac), 31.4 (s, CHHexyl),
29.5–26.8 (m, CH2,Hexyl), 25.6 (s, CH2), 23.8 (s, CH3,Tolyl).
31P {1H} NMR(161 MHz, 300 K, CDCl3): d = 47.1 (s).
MS(FAB): m/z (%) = 500.6 (7, [M+]), 400.7 (100, [M+ ꢀ
Acac]), 318.6 (28, [M+ ꢀ (Acac + cyclohexyl)]). Anal.
Calc. for C25H31O2PPd (500.90): C 59.95; H 6.24; P
6.18; Pd 21.24; Found: C 59.80; H 6.30; P 6.10; Pd 21.20%.
6.2. Preparation of acetylacetonato-[o-(dimesitylphos-
phino)-3,5-dimethylbenzyl]palladium(II) (5a)
To a solution of 1.23 g (1.11 mmol) Pd2(OAc)2[o-
CH2C6H2(CH)2P(Mes)2]2 in 20 ml dichloromethane
300 mg (3 mmol) acetylacetone were added and stirred
for 1 h at room temperature. The solvent was removed
and the residue was washed with cold diethylether.
The product was recrystallized from dichloromethane
as a white solid in 99.9% (658 mg) yield.
6.4. Preparation of acetylacetonato-[o-(t-butyl-o-
tolylphosphino)-benzyl]palladium(II) (5c)
1H NMR (400 MHz, 300 K, CDCl3): d = 7.2 (1H, s,
To a solution of 448 mg (0.5 mmol) Pd2(OAc)2[o-
CH2C6H4P(t-Bu)(o-Tol)]2 in 20 ml dichloromethane
150 mg (1.5 mmol) acetylacetone were added and stirred
for 1 h at room temperature. The solvent was removed
and the residue was washed with diethylether. The prod-
uct was recrystallized from dichloromethane as a white
solid in 99.0% (470 mg) yield.
H
Aryl), 6.8 (4H, s, HMesityl), 6.4 (1H, s, HAryl), 5.15
(1H, s, CHacac), 3.20 (2H, s, PdCH2), 2.20 (3H, s,
CH3,Aryl), 2.15 (12H, s, CH3,Mesityl), 2.12 (3H, s, CH3,Aryl),
1.98 (3H, s, CH3,acac), 1.84 (3H, s, CH3,acac), 1.65 (6H, s,
CH3,Mesityl); 13C {1H} NMR(100 MHz, 300 K, CDCl3):
d = 187.7 (s, COacac), 186.2 (s, COacac), 159.7 (d, CAryl
JPC = 30 Hz), 142.3 (d, CAryl, JPC = 10 Hz), 141.7 (m,
Aryl), 140.0 (d, CAryl, JPC = 2 Hz), 133.8 (s, CAryl),
133.3 (s, CAryl), 131.4 (d, CAryl, JPC = 9 Hz), 129.5 (d,
CAryl JPC = 8 Hz), 126.4 (d, CAryl JPC = 40 Hz),
,
1H NMR (400 MHz, 300 K, CDCl3): d = 7.84 (1H,
3
td, JHH = 8.4 Hz, JHH = 0.8 Hz, HAryl), 7.32 (1H, tt,
4
C
4
3JHH = 7.2 Hz, JHH = 1.2 Hz, HAryl), 7.29 (1H, d,
,
,
3JHH = 7.2 Hz, HAryl), 7.26–7.15 (4H, m, HAryl), 7.05
3
(1H, t, JHH = 7.6 Hz, HAryl), 5.24 (1H, s, CHacac),
125.3–124.5 (m, CAryl), 99.3 (s, CHacac), 28.7 (s, CH3,acac),
28.3 (s, CH3,acac), 26.2 (s, CH2), 25.2 (s, CH3), 24.0 (s,
CH3), 21.3 (s, CH3), 20.9 (s, CH3); 31P {1H} NMR
(161 MHz, 300 K, CDCl3): d = 24.7 (s). MS(FAB):
m/z (%) = 592.6 (5, [M+]), 492.7 (100, [M+ ꢀ Acac]),
478.5 (10, [M+ ꢀ Mes]). Anal. Calc. for C32H39O2PPd
(593.04): C 64.81; H 6.63; Found: C 64.80; H 6.50%.
3
3.47 (2H, d, JHH = 3.6 Hz, PdCH2), 2.54 (3H, s,
CH3,Tolyl), 1.99 (3H, s, CH3,acac), 1.78 (3H, s, CH3,acac),
3
1.50 (9H, d, JHH = 14.8 Hz, CH3,t-Bu). 13C {1H}
NMR(100 MHz, 300 K, CDCl3): d = 188.0 (s, COacac),
186.3 (s, COacac), 158.7 (d, CAryl, JPC = 27 Hz), 143.7
(d, CAryl, JPC = 12 Hz), 135.9 (s, CAryl), 135.4 (s, CAryl),
132.7 (d, CAryl, JPC = 8 Hz), 132.5 (d, CAryl, JPC = 4 Hz),
131.6 (s, CAryl), 131.0 (d, CAryl, JPC = 2 Hz), 130.4 (d,
6.3. Preparation of acetylacetonato-[o-(cyclohexyl-o-
tolylphosphino)-benzyl]palladium(II) (5b)
C
Aryl, JPC = 2 Hz), 129.2 (d, CAryl, JPC = 35 Hz), 128.6
(d, CAryl, JPC = 21 Hz), 125.2 (m, CAryl), 99.5 (s, CHacac),
46.8 (s, C (CH3)3), 35.5 (s, CH3,acac), 35.3 (s, CH3,acac),
28.6 (m, CH3,t-Bu), 23.8 (s, CH3,Tolyl). 31P {1H}
NMR(161 MHz, 300 K, CDCl3): d = 58.1 (s). MS(FAB):
m/z (%) = 473.7 (6, [M+]), 374.7 (100, [M+ ꢀ Acac]), 318.6
(19, [M+ ꢀ (Acac + t-Bu)]), 284.7 (7, [M+ ꢀ (Acac +
o-Tol)]), 226.6 (44, [M+ ꢀ (Acac + t-Bu + o-Tol)]).
Anal. Calc. for C23H29O2PPd (474.86): C 58.18; H 6.16;
P 6.52; Pd 22.41; Found: C 58.80; H 6.20; P 6.55; Pd
22.70%.
To a solution of 461 mg (0.5 mmol) Pd2(OAc)2[o-
CH2C6H4P(Cy)(o-Tol)]2 in 20 ml dichloromethane
150 mg (1.5 mmol) acetylacetone were added and stirred
for 1 h at room temperature. The solvent was removed
and the residue was washed with diethylether. The prod-
uct was recrystallized from DCM as a white solid in
99.8% (500 mg) yield.
1H NMR (400 MHz, 300 K, CDCl3): d = 7.56 (1H,
3
td, JHH = 8.4 Hz, JHH = 0.8 Hz, HAryl), 7.33 (1H, tt,
4
4
3JHH = 7.6 Hz, JHH = 0.8 Hz, HAryl), 7.30 (1H, dd,
4
3JHH = 7.6 Hz, JHH = 1.2 Hz, HAryl), 7.26–7.18 (3H,
m, HAryl), 7.08–7.06 (2H, m, HAryl), 5.26 (1H, s, CHacac),
6.5. Preparation of acetylacetonato-[o-(di-t-butyl-
phosphino)-benzyl]palladium(II) (5d)
3
3.45 (2H, m, JHH = 3.6 Hz, PdCH2), 2.69 (3H, s,
CH3,Aryl), 2.00 (3H, s, CH3,acac), 1.81 (3H, s, CH3,acac),
2.6–1.2 (11H, m). 13C {1H} NMR(100 MHz, 300 K,
To a solution of 401 mg (0.5 mmol) Pd2(OAc)2[o-
CH2C6H4P(t-Bu)2]2 in 20 ml dichloromethane 150 mg

3200
G.D. Frey et al. / Journal of Organometallic Chemistry 690 (2005) 3193–3201
(1.5 mmol) acetylacetone were added and stirred for 1 h
at room temperature. The solvent was removed and the
residue was washed with diethylether. The product was
recrystallized from dichloromethane as a white solid in
99.8% (440 mg) yield.
ꢀ80 ꢁC. The phosphine solution was slowly added via
a syringe to the palladiumacetate solution and slowly
heated up to room temperature and stirred for 12 h.
The solvent was removed via a syringe and the white so-
lid was washed two times with toluene. Yield: 88%
(2350 mg).
1H NMR (400 MHz, 300 K, CDCl3): d = 7.43 (1H, t,
3JHH = 7.1 Hz, HAryl), 7.3–7.2 (2H, m, HAryl), 7.1 (1H, t,
3JHH = 6.7 Hz, HAryl), 5.23 (1H, s, CHacac), 3.30 (2H, d,
3JHH = 4 Hz, PdCH2), 1.93 (3H, s, CH3,acac), 1.84 (3H, s,
1H NMR (400 MHz, 300 K, C6D6): d = 7.80 (1H,
s), 7.61–7.59 (5H, m), 7.44 (1H, s), 6.89–6.62 (9H,
m), 2.15 (3H, s, CH3), 1.79 (3H, s, CO2CH3). 1H
NMR (400 MHz, 300 K, CDCl3): d = 7.77 (1H, s),
3
CH3,acac), 1.36 (18H, d, JHH = 14 Hz, CH3,t-Bu). 13C
{1H} NMR(100 MHz, 300 K, CDCl3): d = 189.0 (s, C
7.57–7.41 (4H, m), 7.25 (4H, d, JHH = 7.6 Hz), 7.16
3
(4H, d, JHH = 7.2 Hz), 7.02 (2H, m), 2.34 (3H, s,
3
O
acac), 187.9 (s, C Oacac), 160.9 (d, CAryl, JPC = 25 Hz),
134.8 (d, CAryl, JPC = 43 Hz), 133.2 (s, CAryl), 132.0 (s,
Aryl), 130.2 (d, CAryl, JPC = 21 Hz), 126.1 (d, CAryl
CH3), 1.77 (3H, s, CO2CH3). 1H NMR (400 MHz,
3
C
,
300 K, (CD3)2SO): d = 7.89 (1H, d, JHH = 6.7 Hz),
JPC = 7 Hz), 100.6 (s, CHacac), 38.2 (s, CH3,acac), 38.0
(s, CH3,acac), 31.4 (s, CH3,t-Bu). 31P {1H}
NMR(161 MHz, 300 K, CDCl3): d = 89.3 (s).
MS(FAB): m/z (%) = 439.7 (12, [M+]), 340.7 (100,
[M+ ꢀ Acac]), 284.7 (17, [M+ ꢀ (Acac + t-Bu)]), 340.7
(41, [M+ ꢀ (Acac + 2 t-Bu)]). Anal. Calc. for
C20H31O2PPd (440.84): C 54.49; H 7.09; P 7.03; Pd
24.14; Found: C 54.40; H 7.10; P 7.10; Pd 24.60%.
7.67–7.05 (14H, m), 1.97 (3H, s, CH3), 1.86 (3H, s,
CO2CH3). 13C {1H} NMR(100 MHz, 300 K,
(CD3)2SO): d = 179.2 (s, C O2CH3), 150.1, 148.6,
139.8, 132.2, 132.1, 131.8, 131.6, 130.9, 130.8, 129.2
(d, JPC = 7.0 Hz), 128.8 (d, JPC = 7.7 Hz), 128.1,
125.6, 125.2, 123.0, 25.1 (CO2CH3), 20.6 (CH3). 31P
{1H} NMR(109 MHz, 300 K, (CD3)2SO): d = 62.1
(s). 31P {1H} NMR(161 MHz, 300 K, CDCl3):
d = 62.6 (s). MS (FAB): m/z (%): 923.6 (23,
[M+ ꢀ OAc]), 864.6 (5, [M+ ꢀ (2*OAc)]), 490.3 (13,
[1/2 (M)+]), 431.3 (100, [1/2 (M ꢀ OAc)+]), 353.2
(19), 325.3 (41), 247.2 (98). Anal. Calc. for
C50H42O4P2Pd2 (981.62): C 61.18; H 4.31; Found: C
60.70; H 4.53%.
6.6. Preparation of acetylacetonato-[o-(dicyclohexyl-
phosphino)-benzyl]palladium(II) (5e)
To a solution of 517 mg (0.5 mmol) Pd2(Br)2[o-
CH2C6H4P(Cy)2]2 in 20 ml dichloromethane 150 mg
(1.5 mmol) acetylacetone and 10 ml 2N NaOH were
added and stirred for 1 h at room temperature. The sol-
vent was removed and the residue was washed with
diethylether. The product was recrystallized from
dichloromethane as a white solid in 99.8% (492 mg)
yield.
1H NMR (400 MHz, 300 K, CDCl3): d = 7.2–7.0
(4H, m, HAryl), 5.22 (1H, s, CHacac), 3.20 (2H, d,
J = 3.5 Hz, PdCH2), 1.99 (3H, s, CH3,acac), 1.90 (3H, s,
CH3,acac), 2.2–1.1 (22H, m). 13C {1H} NMR(100 MHz,
300 K, CDCl3): d = 187.9 (s, C Oacac), 186.6 (s, C Oacac),
6.8. Preparation of acetylacetonato-[5-(diphenyl-
phosphino)-2-methylnaphthyl]palladium(II) (8)
To a solution of 290 mg (0.29 mmol) trans-di(l-ace-
tato)-bis[5-(diphenylphosphino)-2-methylnaphthyl]di-
palladium(II) (7) dissolved in 20 ml dichloromethane
90 mg (0.9 mmol) acetylacetone were added and stirred
for 2 h at room temperature. The solvent was removed
and the residue was washed with diethylether. The prod-
uct was recrystallized from dichloromethane as a white
solid in 99.8% (313 mg) yield.
159.8 (d, CAryl
JPC = 47 Hz), 130.9 (s, CAryl), 130.2 (d, CAryl
,
JPC = 27 Hz), 132.6 (d, CAryl
,
,
1H NMR (400 MHz, 300 K, CDCl3): d = 8.28 (1H, d,
3JHH = 3.6 Hz), 7.82–7.77 (5H, m), 7.57 (1H, d,
3JHH = 7.2 Hz), 7.45–7.39 (7H, m), 7.25 (1H, d,
3JHH = 2.4 Hz), 5.31 (1H, s CHacac), 2.16 (3H, s,
CH3,acac), 2.11 (3H, s, CH3,acac), 1.85 (3H, s, CH3).
JPC = 18 Hz), 128.4 (d, CAryl, JPC = 21 Hz), 125.2 (d,
Aryl, JPC = 7 Hz), 99.5 (s, CHacac), 34.8 (s, CH3,acac),
C
34.5 (s, CH3,acac), 27.9 (CH2), 28.8–26.5 (CHexyl). 31P
{1H} NMR (161 MHz, 300 K, CDCl3): d = 66.7 (s).
Anal. Calc. for C24H35O2PPd (492.91): C 58.48; H
7.16; P 6.28; Pd 21.59; Found: C 58.50; H 7.20; P
6.30; Pd 22.00%.
13C {1H} NMR(100 MHz, 300 K, CDCl3): d = 187.7 (s,
2
COacac), 187.1 (s, COacac), 151.9, 151.2, 149.4 (d, JPC
=
5.1 Hz), 140.1, 133.0, 132.8, 132.2, 132.1, 130.6, 130.1,
129.7, 129.2, 128.9, 128.8, 128.6, 128.5, 125.9, 123.3
(CAr), 99.6 (s, CHacac), 28.3 (CH3,acac), 28.1 (CH3,acac),
21.8 (d, 3JPC = 3.9 Hz, CH3). 31P {1H} NMR(161 MHz,
300 K, CDCl3): d = 61.7 (s). MS(FAB): m/z (%): 430.4
(M ꢀ Acac). Anal. Calc. for C28H25O2PPd2 Æ1/4DCM
(552.12): C 61.45; H 4.66; Cl 3.21; Found: C 61.26; H
4.64; Cl 2.85%.
6.7. Preparation of trans-di(l-acetato)-bis[5-(diphenyl-
phosphino)-2-methylnaphthyl]dipalladium(II) (7)
The phosphine [(2-methylnaphthyl)diphenylphos-
phane] (6) (5.50 mmol) and Pd(OAc)2 (5.43 mmol) were
each dissolved in dry toluene (10 ml) and cooled to

G.D. Frey et al. / Journal of Organometallic Chemistry 690 (2005) 3193–3201
3201
(f) W.A. Herrmann, Angew. Chem. 114 (2002) 1342;
Angew. Chem. Int. Ed. Engl. 41 (2002) 1290.
6.9. General method for the Heck–Mizoroki coupling of
arylhalides with styrene
[3] (a) A.J. Cheney, B.L. Shaw, J. Chem. Soc., Dalton Trans. (1972)
754;
The base (1.5 mmol) and tetrabutylammoniumbromid
(0.2 mmol), in the cases when it was used, were placed in a
Schlenk tube equipped with a stirring bar. The flask was
put under an atmosphere of argon, and aryl halide
(1.0 mmol), styrene (156 mg, 170 ml, 1.5 mmol), 50 mg
of diethyleneglycol-di-n-butylether and 2 ml of degassed
solvent were added. After thermostating at 130 ꢁC for
10 min the catalyst was added against a positive stream
of argon. To determine the yield the mixture was stirred
for 14 h. To finish the reaction, the mixture was allowed
to cool to room temperature and 3 ml of 1 M HCl(aq.)
was added. The aqueous phase was extracted three times
with 2 ml of dichloromethane, the combined organic
phases were dried over MgSO4, and the solution analyzed
on a gas chromatograph.
(b) B.L. Shaw, New J. Chem. (1998) 77.
[4] (a) E.C. Aleya, S.A. Dias, G. Ferguson, P.J. Roberts, J. Chem.
Soc., Dalton Trans. (1979) 948;
(b) E.C. Aleya, G. Ferguson, J. Malito, B.L. Ruhl, Organomet-
allics 8 (1989) 1188.
[5] T. Mitsudo, W. Fischetti, R.F. Heck, J. Org. Chem. 49 (1984)
1640.
¨
[6] (a) W.A. Herrmann, C. Broßmer, K. Ofele, C.-P. Reisinger, T.
Priermeier, M. Beller, H. Fischer, Angew. Chem. 107 (1995) 1989;
Angew. Chem. Int. Ed. Engl. 34 (1995) 1844;
(b) W.A. Herrmann, C. Broßmer, C.-P. Reisinger, T.H. Rierme-
¨
ier, K. Ofele, M. Beller, Chem. Eur. J. 3 (1997) 1357;
(c) W.A. Herrmann, V.P.W. Bo¨hm, J. Organomet. Chem. 572
(1999) 141;
(d) V.P.W. Bo¨hm, W.A. Herrmann, Chem. Eur. J. 6 (2000) 1017;
¨
(e) M. Beller, H. Fischer, W.A. Herrmann, K. Ofele, C. Broßmer,
Angew. Chem. 107 (1995) 1992;
Angew. Chem. Int. Ed. Engl. 34 (1995) 1848;
¨
(f) W.A. Herrmann, C.-P. Reisinger, K. Ofele, C. Broßmer, M.
Beller, H. Fischer, J. Mol. Catal. A 108 (1996) 51;
(g) M. Beller, T.H. Riermeier, C.-P. Reisinger, W.A. Herrmann,
Tetrahedron Lett. 38 (1997) 2073;
7. Supplementary material
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data
Centre as supplementary publication no. CCDC-
270649 (5e) and CCDC-270648 (7). Copies of the data
can be obtained free of charge on application to CCDC,
12 Union Road, Cambridge CB2 1EZ, UK (fax: +44
1223 336 033; e-mail: deposit@ccdc.cam.ac.uk).
(h) W.A. Herrmann, V.P.W. Bo¨hm, C.-P. Reisinger, J. Chem.
Educ. 77 (2000) 92;
(i) V.P.W. Bo¨hm, W.A. Herrmann, Chem. Eur. J. 7 (2001) 4191;
¨
(j) W.A. Herrmann, K. Ofele, D. v. Preysing, S.K. Schneider, J.
Organomet. Chem. 687 (2003) 229.
[7] B.L. Shaw, S.D. Perera, E.A. Staley, Chem. Commun. (1998)
1361.
[8] (a) C.-P. Reisinger, Ph.D. Thesis, Technische Universita¨t Mun-
¨
chen, 1997, ISBN 3-933083-00-1;
(b) W.A. Herrmann, V.P.W. Bo¨hm, C.-P. Reisinger, J. Organo-
met. Chem. 576 (1999) 23.
Acknowledgements
[9] (a) J. Tsuji, Palladium reagents and catalysts, Wiley & Sons,
Chichester, 1995;
(b) L. Brandsma, S.F. Vasilevsky, H.D. Verkruijsse, Application
of transition metal catalysts in organic synthesis, Springer, Berlin,
1998;
We thank the Karl-Wamsler Foundation for financial
¨
support. Helpful suggestions by Dr. K. Ofele are grate-
fully acknowledged. We also thank Martin Schneider
for experimental assistance.
(c) F. Diederich, P.J. Stang (Eds.), Metal-catalyzed Cross-
coupling Reactions, Wiley-VCH, Weinheim, 1998.
[10] A.W. Hofmann, Justus Liebigs Ann. Chem. 78 (1851) 553.
[11] (a) Data Collection Software for Nonius j-CCD devices, Delft,
The Netherlands, 2001;
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