Synthesis, characterization, and catalytic applications of palladacyclic complexes bearing C,N,S-donor ligands

Article abstract of DOI:10.1002/ejic.200600601

The preparations of novel tridentate C,N,S-donor ligand precursors, PhN=C(CMe₂)(NPh)C=N(CH₂)₂SR [R = CMe ₃ (2); R = Ph (3)] are described. Treatment of 2 and 3 with 1 equiv. of Pd(OAc)₂ affords the or

Full text of DOI:10.1002/ejic.200600601

FULL PAPER
DOI: 10.1002/ejic.200600601
Synthesis, Characterization, and Catalytic Applications of Palladacyclic
Complexes Bearing C,N,S-Donor Ligands
Ming-Tsz Chen,[a] Chi-An Huang,[a] and Chi-Tien Chen*[a]
Keywords: Palladacyclic complexes / Pendant thioether / Suzuki reaction / Heck reaction / Palladium
The preparations of novel tridentate C,N,S-donor ligand pre-
cursors, PhN=C(CMe2)(NPh)C=N(CH2)2SR [R = CMe3 (2); R
= Ph (3)] are described. Treatment of 2 and 3 with 1 equiv. of
Pd(OAc)2 affords the orthometallated palladium(II) com-
plexes [PhN=C(CMe2)(N-η1-Ph)C=N(CH2)2SR]Pd(OAc) [R =
CMe3 (4); R = Ph (5)]. Reaction of 4 and 5 with an excess
of LiCl in methanol affords the orthometallated palladium(II)
complexes [PhN=C(CMe2)(N-η1-Ph)C=N(CH2)2SR]PdCl [R =
CMe3 (6); R = Ph (7)]. Crystal structures are reported for com-
pounds 3 and 4. The application of these novel palladacyclic
complexes as catalyses for the Suzuki and Heck reactions
with aryl halide substrates was examined.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
Introduction
Results and Discussion
Due to the powerful application of, and versatile meth-
ods for, the formation of carbon-carbon bonds, palladium-
catalyzed coupling reactions have been an attractive area of
research.[1–19] Among these studies, the search for appropri-
ate ancillary ligands that can serve as catalyst precursors is
of current interest. Palladacycles bearing a metallated car-
bon atom and dative group(s) are the most active catalyst
precursors for the promotion of such reactions.[2–8,11–17,19]
These complexes are usually formed as dinuclear species
with bridged ligands, or as mononuclear species in the pres-
ence of ligands with neutral dative groups. In order to im-
prove the stability and efficiency of catalytic palladium
complexes, various families of palladium based catalyst pre-
cursors have been developed. Recently, some sulfur contain-
ing palladacycles that function as excellent catalyst precur-
sors for coupling reactions have been reported. [20–30] Their
success in catalyzing cross-coupling reactions encouraged
us to study the catalytic performance exhibited by pallada-
cycles with pendant thioether functionalities. Following our
previous work on four-membered ring diimino pallada-
cycles,[31] we report here the synthesis and characterization
of novel mononuclear palladacycles incorporating unsym-
metrical C,N,S-donor ligands. Their catalytic activities to-
ward the Suzuki and Heck reactions were investigated.
Syntheses and Characterization of Ligand Precursors and
Palladacycles
Pre-ligand compound 1 was prepared by the reaction
of 2,2-dimethyl-N,NЈ-diphenylpropanediimidoyl dichloride
with 3.0 equiv. of 2-chloroethylamine hydrochloride in the
presence of 4.0 equiv. of NEt3 using a similar procedure to
that reported in the literature.[31] The new ligand precursors
2 and 3 were synthesized from 1 via a nucleophilic substitu-
tion reaction with the corresponding thiol [R = C(CH3)3
for 2; R = Ph for 3].[20] Compounds 1, 2, and 3 were charac-
terized by NMR spectroscopy and elemental analysis,
which indicated that they are four-membered ring diimine
compounds with the different functionalities. A summary
of the synthetic route and the proposed structures is shown
in Scheme 1. The X-ray structure of 3 features a four-mem-
bered diimine ring bearing a pendant thioether functional
group. The molecular structure is shown in Figure 1, and
selected bond lengths and angles are listed in Table 1. The
C(1)–N(1) [1.253(2) Å] and C(3)–N(3) [1.257(2) Å] bond
lengths are consistent with these bonds possessing signifi-
cant double bond character, and the bond angles around
the imino C and N atoms are indicative of sp2 hybridized
centers.
Treatment of 2 and 3 with 1 equiv. of Pd(OAc)2 at room
temperature yields complexes 4 and 5, respectively, as pale
brown solids. Similar to the results reported previously,[31]
an additional tertiary carbon was found in the phenyl ring
region of the 13C{1H} NMR spectrum that indicates the
presence of a metallated carbon atom, which was created
during the reactions. Crystals of 4 suitable for structural
determination were obtained from a CH2Cl2/hexane solu-
[a] Department of Chemistry, National Chung Hsing University,
Taichung 402, Taiwan, Republic of China
Fax: +886-4-22862547
E-mail: ctchen@dragon.nchu.edu.tw
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The Synthesis and Properties of Palladacyclic Complexes
FULL PAPER
Scheme 1.
a slightly distorted square planar geometry, in which the
palladium metal center is coordinated to one imine nitrogen
atom, one thioether sulfur atom, one carbon atom, and one
OAc oxygen atom. The N–Pd–Cmetallated bite angle
[93.47(12)°] involving the imino nitrogen and metallated
carbon atoms is similar to those [93.20(104)°, 93.77(8)°, and
94.51(10)°] found in our previous work.[31] The N–Pd–S
bite angle [84.62(8)°] involving the imino nitrogen atom and
the pendant group is in the range [84.46(10)–85.1(1)°] found
for C,N,S-donor complexes with two carbon spacer atoms
Figure 1. Molecular structure of compound 3. Hydrogen atoms
bound to carbon atoms have been omitted for clarity.
Table 1. Selected bond lengths [Å] and angles [°] for 3.
S–C(14)
1.751(2)
1.252(2)
1.403(2)
1.413(2)
1.467(3)
104.20(10)
S–C(13)
1.789(2)
1.427(2)
1.411(2)
1.251(2)
N(1)–C(7)
N(2)–C(7)
N(2)–C(20)
N(3)–C(12)
C(14)–S–C(13)
N(1)–C(1)
N(2)–C(11)
N(3)–C(11)
C(7)–N(1)–C(1)
119.15(15)
C(7)–N(2)–C(11) 93.61(13)
C(11)–N(2)–C(20) 133.33(16)
C(7)–N(2)–C(20) 133.05(15)
C(11)–N(3)–C(12) 118.34(17)
Figure 2. Molecular structure of complex 4. Hydrogen atoms
bound to carbon atoms have been omitted for clarity. Dichloro-
methane and water molecules are omitted for clarity.
N(1)–C(7)–N(2)
N(2)–C(7)–C(8)
128.08(16)
91.58(14)
N(1)–C(7)–C(8)
140.33(17)
C(7)–C(8)–C(11) 83.57(13)
N(3)–C(11)–C(8) 141.54(17)
N(3)–C(11)–N(2) 127.21(17)
N(2)–C(11)–C(8) 91.22(14)
Table 2. Selected bond lengths [Å] and angles [°] for 4.
Pd–N(3)
Pd–O(1)
N(3)–Pd–C(23)
C(23)–Pd–O(1)
C(23)–Pd–S
2.011(3)
2.036(2)
93.47(12)
91.47(13)
176.85(11)
Pd–C(23)
Pd–S
N(3)–Pd–O(1)
N(3)–Pd–S
O(1)–Pd–S
2.022(4)
2.4093(9)
174.95(11)
84.62(8)
90.40(8)
tion. The molecular structure is shown in Figure 2, and se-
lected bond lengths and angles are listed in Table 2. The
bond angles [in the range of 84.62(8) to 93.47(12)°] around
the palladium metal center indicate that the complex has
Eur. J. Inorg. Chem. 2006, 4642–4648
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4643

M.-T. Chen, C.-A. Huang, C.-T. Chen
FULL PAPER
between the nitrogen and sulfur atoms.[32–34] The Pd–S a 1 mol-% scale. Selected results are listed in Table 3. The
bond length [2.4093(9) Å] is in the range [2.240(1)– optimum conditions for the reaction were found to be
2.422(1) Å] found for palladium complexes containing thio- K3PO4/toluene, Cs2CO3/DMA, and Cs2CO3/DMF for 4
ether functionalities.[23,25,30,32–37] The Pd–Cmetallated bond (entries 1–3); K3PO4/DMF for 5 (entry 4); Cs2CO3/THF,
length [2.022(4) Å] is in the range [1.964(3)–2.034(2) Å] Cs2CO3/toluene, and Cs2CO3/DMA for 6 (entries 5–7);
found for palladacycles with metallated carbon.[23,31–34,38] Cs2CO3/THF for 7 (entry 8). Higher reactivity was ob-
The Pd–NC=N bond length [2.011(3) Å] is within the range served, under optimum conditions, for palladacycles con-
[1.985(3)–2.098(2) Å] found for palladacycles.[31–34,38] The taining a pendant tBuS moiety. Moreover, compounds con-
Pd–OOAc bond length [2.036(2) Å] is comparable to those taining an acetate group demonstrated slightly higher cata-
[2.0027(9)–2.105(2) Å] found in the literature.[31,39–41] The lytic activities than those containing a Cl group.
reaction of 4 and 5 with an excess of lithium chloride, in
methanol at room temperature, yielded complexes 6 and 7,
respectively, as yellow solids.[42] Compounds 6 and 7
were characterized by NMR spectroscopy and elemental
analysis. Basically, 6 and 7 are quite similar to 4 and 5, but
with Cl coordinated to the metal centre instead of an OAc
group.
Catalytic Studies
Due to the success of some sulfur containing pallada-
cycles in catalyzing cross-coupling reactions,[20–30] the palla-
Scheme 2. Application of the palladacycles in the Suzuki reaction.
dacycles discussed above are expected to catalyze carbon-
carbon coupling reactions. For the purpose of comparing
the reactivity of complexes 4–7 with other palladacycles, the
Although both sets of optimized conditions, K3PO4/tolu-
Suzuki reaction was chosen to demonstrate the catalytic ac- ene and Cs2CO3/DMF, for 4 exhibited similar conversion
tivities of these sulfur containing complexes, as shown in levels with electronically activated aryl bromide (entries 1–
Scheme 2. The potential catalyst precursor candidates 4–7 2 and 9–12), poor conversion levels were observed for reac-
were investigated in the coupling of 4-bromoacetophenone tions with electronically deactivated compounds using
with phenylboronic acid at 50 °C, over a period of 1 h on Cs2CO3/DMF (entries 14–15 and 17–18). Therefore the op-
Table 3. Suzuki coupling reactions catalysed by the new palladium complexes.[a]
Entry
Catalyst
Aryl halide
Base
Solvent
[Pd] (mol-%) T [°C]
t [h]
Conversion (%)[b] Yield (%)[c]
1
2
3
4
5
6
7
8
4
4
4
5
6
6
6
7
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4-bromoacetophenone
4-bromoacetophenone
4-bromoacetophenone
4-bromoacetophenone
4-bromoacetophenone
4-bromoacetophenone
4-bromoacetophenone
4-bromoacetophenone
4-bromobenzaldehyde
methyl 4-bromobenzoate
4-bromobenzaldehyde
methyl 4-bromobenzoate
4-bromotoluene
4-tert-butylbromobenzene
4-bromoanisole
4-bromotoluene
4-tert-butyl-bromobenzene Cs2CO3
4-bromoanisole
4-bromoacetophenone
4-bromoacetophenone
4-chloroacetophenone
4-chloroacetophenone
methyl 4-chlorobenzoate
4-chloroanisole
K3PO4
Cs2CO3
Cs2CO3
K3PO4
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
K3PO4
K3PO4
Cs2CO3
Cs2CO3
K3PO4
K3PO4
K3PO4
Cs2CO3
toluene
DMF
DMA
DMF
THF
toluene
DMA
THF
toluene
toluene
DMF
DMF
toluene
toluene
toluene
DMF
DMF
DMF
toluene
toluene
toluene
DMF
DMF
DMF
DMF
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
50
50
50
50
50
50
50
50
50
50
50
50
110
70
70
135
70
70
80
80
80
80
80
80
135
1
1
1
1
1
1
1
1
1
1
1
1
0.75
3.5
4
0.75
3.5
4
2.5
5
4
96
98
94
92
87
90
88
87
99
99
96
99
99
92
97
99
83
83
87
99
9
90
92
83
85
82
88
85
76
92
95
90
94
90
86
90
89
75
76
81
96
–
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
1
1
Cs2CO3
K3PO4
K3PO4
K3PO4
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
0.01
0.002
1
1
1
1
1
4
4
7
4
85
72
82
92
80
70
75
90
4-chloroacetophenone
1
[a] Reaction conditions: 1.0 mmol aryl halide, 1.5 mmol phenylboronic acid, 2.0 mmol base, 2 mL solvent. [b] Determined by H NMR
spectroscopy. [c] Isolated yield (average of two experiments).
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Eur. J. Inorg. Chem. 2006, 4642–4648

The Synthesis and Properties of Palladacyclic Complexes
FULL PAPER
timized conditions, K3PO4/toluene, were chosen for use in after 24 h (entries 8 and 9). Compound 4 also showed cata-
further studies to examine the limitations of the catalytic lytic activity for reactions involving both electronically acti-
capability of compound 4. Due to the high reactivity of 4, vated and deactivated aryl chlorides; however, higher cata-
lower catalyst concentrations were required, catalyst/sub- lyst loadings were necessary (entries 10 and 11).
strate ratios from 10–4 to 2×10–5 were employed, leading to
turnover numbers of up to 48000 within a 5 h period (en-
tries 19–20). Similar conditions were applied during the re-
action of the electronically activated aryl chloride with
1 mol-% catalyst loading; however, poor conversion levels
were observed after 4 h (entry 21). Surprisingly, the percen-
tage conversion increased to 85% after 4 h (entry 22) using
Cs2CO3/DMF. These conditions were employed in a reac-
tion using methyl 4-chlorobenzoate and resulted in percen-
tage conversion levels of up to 72% within 4 h (entry 23).
A similar conversion level was observed using electronically
deactivated aryl chloride and 4-chloroanisole as substrates;
however, the reaction took up to 7 h (entry 24). In order to
Scheme 3. Application of the palladacycles in the Heck reaction.
compare the catalytic activities with the sulfur containing
palladacycles,[22] the optimized conditions at 110 °C and
135 °C were employed in the reaction with 4-bromotoluene
as the substrate, this gave conversion levels of up to 99%
within 0.75 h (entries 13 and 16). A similar conversion level
was observed using electronically activated aryl chloride
and 4-chloroacetophenone as the substrates; however, the
reaction took up to 4 h at 135 °C (entry 25).
Summary
Mononuclear phosphane-free palladacycles have been
prepared using tridentate ligands containing carbon, nitro-
In order to determine the influence of the pendant func- gen, and sulfur. Under optimized conditions, palladacycle
tionality on the catalytic activity,[21] compounds 4–7 were 4 exhibits catalytic activity comparable to existing sulfur
investigated as catalysts in the Heck coupling reaction of 4- containing palladacyclic systems employed in the Suzuki
bromoacetophenone with styrene at 135 °C over a period coupling reaction. Complex 4 exhibits higher catalytic ac-
of 1.5 h on a 1 mol-% scale, as shown in Scheme 3. Selected tivity in some cases than in others. The catalyst productivity
results are listed in Table 4. The optimum conditions were for the coupling of an electronically activated aryl bromide
found to be Cs2CO3/DMF for 4 (entry 1); KF/DMA for 5 with phenylboronic acid was observed with a turnover of up
(entry 2); K3PO4/DMA for 6 (entry 3); KF/DMA for 7 (en- to 48000 during a 5 h period. Complex 4 also demonstrates
try 4). High reactivity was observed for 4 under optimized catalytic activity with less reactive aryl chlorides containing
conditions. A similar conversion level was observed using both electron withdrawing and electron donating groups. In
methyl 4-bromobenzoate as the substrate (entry 5). Similar the case of the four-membered diimine palladacyclic sys-
conditions were applied to the reactions employing the elec- tem, the thioether containing palladacycle exhibits better
tronically deactivated aryl bromide compounds; however, catalytic activity for the Heck coupling reaction than the
the reactions took up to 6 h (4-bromotoluene) and 12 h (4- nitrogen containing palladacycles reported in our previous
bromoanisole) at 135 °C (entries 6 and 7). Lower catalyst work. Studies relating to the fine-tuning of the ligands, and
concentrations, catalyst/substrate ratios of 10–3 to 10–5, led investigations into further catalytic applications for metal
to percentage conversion levels of 81% after 6 h and 21% complexes are currently underway.
Table 4. Heck coupling reactions catalysed by the new palladium complexes.[a]
Entry
Catalyst Aryl halide
Base
Solvent
[Pd] (mol-%) T [°C]
t [h]
Conversion (%)[b] Yield (%)[c]
1
2
3
4
5
6
7
8
4
5
6
7
4
4
4
4
4
4
4
4-bromoacetophenone
Cs2CO3 DMF
1
1
1
1
1
1
1
135
135
135
135
135
135
135
135
135
135
135
1.5
1.5
1.5
1.5
1.5
6
12
6
24
48
48
92
84
80
89
95
99
96
81
21
57
56
86
–
–
4-bromoacetophenone
4-bromoacetophenone
4-bromoacetophenone
methyl 4-bromobenzoate Cs2CO3 DMF
4-bromotoluene
KF
K3PO4
KF
DMA
DMA
DMA
–
90
87
91
75
–
Cs2CO3 DMF
Cs2CO3 DMF
Cs2CO3 DMF
Cs2CO3 DMF
Cs2CO3 DMF
Cs2CO3 DMF
4-bromoanisole
4-bromoacetophenone
4-bromoacetophenone
4-chloroacetophenone
4-chloroanisole
0.1
0.001
3
9
10
11
–
–
5
[a] Reaction conditions: 1.0 mmol aryl halide, 1.3 mmol styrene, 1.5 mmol base, 2 mL solvent. [b] Determined by 1H NMR spectroscopy.
[c] Isolated yield (average of two experiments).
Eur. J. Inorg. Chem. 2006, 4642–4648
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M.-T. Chen, C.-A. Huang, C.-T. Chen
FULL PAPER
3
3
2 H, CH2), 3.63 (t, J = 7.2 Hz, 2 H, CH2), 6.91 (d, J = 7.2 Hz, 2
Experimental Section
3
3
H, o-Ph), 7.06 (t, J = 7.2 Hz, 1 H, p-Ph), 7.14 (t, J = 7.2 Hz, 1
3
General Procedure: All manipulations were carried out under nitro-
gen using standard Schlenk-line or drybox techniques. Solvents
(THF, toluene, CH2Cl2 and hexane) were refluxed over an appro-
priate drying agent and distilled prior to use. Methanol (Merck,
99.9%), DMA (TEDIA, 99%) and DMF (TEDIA, 95%) were used
as supplied. Deuterated solvents were dried over molecular sieves.
1H and 13C{1H} NMR spectra were recorded on Varian Gemini-
200 (200 MHz), Varian Mercury-400 (400 MHz) and Varian Inova-
600 (600 MHz) spectrometers. Spectra were recorded in chloro-
form-d at ambient temperature unless otherwise stated, and refer-
enced internally to the residual solvent peak, and reported as parts
per million relative to tetramethylsilane. Elemental analyses were
performed with an Elementar Vario ELIV instrument.
H, p-Ph), 7.16 (t, J = 7.2 Hz, 1 H, p-Ph), 7.26 (m, overlap, 4 H,
3
Ph), 7.37 (m, overlap, 4 H, Ph), 8.24 ppm (d, J = 7.8 Hz, 2 H, o-
Ph). 13C{1H} NMR (150 MHz, CDCl3): δ = 21.5 [s, C(CH3)2], 35.2
(s, CH2), 48.3 (s, CH2), 58.0 [s, C(CH3)2], 119.4, 121.4, 123.3, 124.5,
126.1, 128.6 (overlap), 128.9, 129.3 (CH-C6H5), 136.1, 137.1, 146.7,
157.9, 168.8 ppm (three Cipso-C6H5, and two C=N groups).
C25H25N3S (399.55): calcd. C 75.15, H 6.31, N 10.52; found C
75.31, H 6.09, N 10.55.
[PhN=CA(CBMe2)(NB-η1-C6H4)CC=N(CH2)2S(CMe3)(CA–NB)-
(CB–CC)]Pd(OAc) (4): To a flask containing Pd(OAc)2 (0.11 g,
0.50 mmol) and 2 (0.19 g, 0.50 mmol), 30 mL THF was added at
room temperature. After 12 h of stirring, the yellow suspension was
filtered and the filtrate was dried in vacuo to afford a pale brown
1
solid. Yield, 0.22 g, 79.2%. H NMR (600 MHz, CDCl3): δ = 1.47
Chemicals were used as supplied unless otherwise stated. NEt3 was
dried with CaH2 and distilled before use. 2,2-Dimethyl-N,NЈ-di-
phenyl-malonamide and 2,2-dimethyl-N,NЈ-diphenylpropanediimi-
doyl dichloride were prepared by a method reported in the litera-
ture.[31]
[s, 6 H, C(CH3)2], 1.58 [s, 9 H, C(CH3)3], 2.16 [s, 3 H, O-C(=O)-
3
CH3], 2.71 (t, 3J = 6.0 Hz, 2 H, CH2), 3.76 (t, J = 6.0 Hz, 2 H,
3
3
CH2), 6.94 (d, J = 7.2 Hz, 2 H, o-Ph), 7.06 (t, J = 7.2 Hz, 1 H,
3
3
CH-Ph), 7.13 (t, J = 7.2 Hz, 1 H, CH-Ph), 7.17 (t, J = 7.2 Hz, 1
3
3
H, CH-Ph), 7.33 (t, J = 7.8 Hz, 2 H, m-Ph), 7.59 (d, J = 8.4 Hz,
1 H, CH-Ph), 8.09 ppm (d, 3J = 7.8 Hz, 1 H, CH-Ph). 13C{1H}
NMR (150 MHz, CDCl3): δ = 21.0 [s, C(CH3)2], 24.6 [s, O-C(=O)-
CH3], 30.0 [s, C(CH3)3], 30.7 (s, CH2), 48.6 [s, C(CH3)3], 52.6 (s,
CH2), 57.0 [s, C(CH3)2], 116.6, 120.8, 124.1, 124.8, 125.5, 129.0,
134.1 (CH-C6H5), 129.6, 129.9, 145.5, 153.2, 158.7 (one η1-Ph, two
Cipso-C6H5 and two C=N groups), 177.6 ppm [s, O-C(=O)-CH3].
C25H31N3O2PdS (544.02): calcd. C 55.19, H 5.74, N 7.72; found C
54.72, H 5.99, N 7.34.
[PhN=CA(CBMe2)(NB-η1-C6H4)CC=N(CH2)2SPh(CA–NB)(CB–
CC)]Pd(OAc) (5): The procedure for the preparation of 5 was sim-
ilar to that used for 4; however, compound 3 was used instead of
2. A pale brown solid was obtained. Yield, 0.18 g, 61.9%. 1H NMR
(600 MHz, CDCl3): δ = 1.44 [s, 6 H, C(CH3)2], 2.08 [s, 3 H, OC(O)
CH3], 2.98 (t, 3J = 6.0 Hz, 2 H, CH2), 3.65 (t, 3J = 6.0 Hz, 2 H,
CH2), 6.93 (m, 2 H, CH-Ph), 7.11 (m, 1 H, CH-Ph), 7.13 (m, 1 H,
CH-Ph), 7.21 (m, 1 H, CH-Ph), 7.33 (m, 2 H, CH-Ph), 7.43 (m, 3
H, CH-Ph), 7.78 (m, 1 H, CH-Ph), 8.13 ppm (m, 3 H, CH-Ph).
13C{1H} NMR (150 MHz, CDCl3): δ = 21.0 [s, C(CH3)2], 24.0 [s,
O-C(=O)-CH3], 39.2 (s, CH2), 52.1 (s, CH2), 57.1 [s, C(CH3)2],
116.7, 120.8, 124.2, 124.9, 125.8, 129.0, 129.6, 129.7, 133.5, 134.4
(CH-C6H5), 129.76, 129.82, 129.87, 145.5, 153.2, 158.8 (one η1-Ph,
three Cipso-C6H5 and two C=N groups), 177.3 ppm [s, O-C(=O)-
CH3]. C27H27O2N3PdS (564.01): calcd. C 57.50, H 4.83, N 7.45;
found C 57.26, H 5.08, N 7.36.
PhN=CA(CBMe2)(NBPh)CC=N(CH2)2Cl(CA–NB)(CB–CC) (1): To a
flask containing 2,2-dimethyl-N,NЈ-diphenylpropanediimidoyl di-
chloride (2.5 g, 8.0 mmol) and NEt3 (4.5 mL, 32 mmol), 40 mL
CH2Cl2, 2-chloroethylamine hydrochloride (2.8 g, 24 mmol) was
added at 0 °C. The reaction mixture was warmed to room tempera-
ture and left to react overnight. After 14 h of stirring, the volatiles
were removed in vacuo, and the residue was extracted with 30 mL
toluene. After removal of solvent, the residue was washed with
5 mL hexane to afford a white solid. Yield, 1.84 g, 70.5%. 1H NMR
(600 MHz, CDCl3): δ = 1.46 [s, 6 H, C(CH3)2], 3.74 [m, 4 H,
3
(CH2)2], 6.94 (d, J = 7.2 Hz, 2 H, o-Ph), 7.08 (t, 3J = 7.8 Hz, 1 H,
3
3
p-Ph), 7.16 (t, J = 7.2 Hz, 1 H, p-Ph), 7.30 (t, J = 7.8 Hz, 2 H,
3
3
m-Ph), 7.39 (t, J = 7.8 Hz, 2 H, m-Ph), 8.27 ppm (d, J = 7.8 Hz,
2 H, o-Ph). 13C{1H} NMR (150 MHz, CDCl3): δ = 21.7 [s,
C(CH3)2], 45.0 [s, (CH2)2], 50.4 [s, (CH2)2], 58.0 [s, tert-C(CH3)2],
119.4, 121.4, 123.4, 124.6, 128.7 (overlap) (o, m, p-C6H5), 137.1,
146.7, 157.8, 159.6 ppm (two Cipso-C6H5 and two C=N groups).
C19H20N3Cl (325.84): calcd. C 70.04, H 6.19, N 12.90; found C
69.88, H 6.28, N 12.74.
PhN=CA(CBMe2)(NBPh)CC=N(CH2)2S(CMe3)(CA–NB)(CB–CC)
(2): To a flask containing 1 (0.49 g, 1.5 mmol) and K2CO3 (0.62 g,
4.5 mmol), 40 mL DMF, 2-methyl-2-propanethiol (0.34 mL,
3.0 mmol) was added. The reaction mixture was heated to 70 °C
and left to react overnight. After 16 h of stirring, the resulting sus-
pension was cooled to room temperature. Water (ca. 30 mL) was
added into the suspension, which was then put into the fridge, and
subsequently afforded a white solid. Yield, 0.49 g, 85.4%. 1H NMR
(600 MHz, CDCl3): δ = 1.35 [s, 9 H, C(CH3)3], 1.45 [s, 6 H,
[PhN=CA(CBMe2)(NB-η1-C6H4)CC=N(CH2)2S(CMe3)(CA–NB)-
(CB–CC)]PdCl (6): To a flask containing 4 (0.14 g, 0.25 mmol) and
LiCl (0.04 g, 1.0 mmol) 30 mL methanol was added at room tem-
perature. After 0.5 h of stirring, the yellow suspension was filtered
and the precipitate was washed with 20 mL deionized water fol-
lowed by 20 mL hexane to afford a yellow solid. Yield, 0.068 g,
3
3
C(CH3)2], 2.80 (t, J = 7.2 Hz, 2 H, CH2), 3.57 (t, J = 7.8 Hz, 2
3
3
H, CH2), 6.93 (d, J = 7.2 Hz, 2 H, o-Ph), 7.07 (t, J = 7.2 Hz, 1
3
3
H, p-Ph), 7.14 (t, J = 7.2 Hz, 1 H, p-Ph), 7.28 (t, J = 7.8 Hz, 2
H, m-Ph), 7.38 (t, 3J = 7.8 Hz, 2 H, m-Ph), 8.27 ppm (d, 3J =
7.8 Hz, 2 H, o-Ph). 13C{1H} NMR (150 MHz, CDCl3): δ = 21.7 [s,
C(CH3)2], 30.2 (s, CH2), 31.0 [s, C(CH3)3], 42.2 [s, C(CH3)3], 49.1
(s, CH2), 58.0 [s, C(CH3)2], 119.4, 121.5, 123.3, 124.4, 128.6 (over-
lap) (CH-C6H5), 137.2, 146.8, 158.0, 158.4 ppm (two Cipso-C6H5,
and two C=N groups). C23H29N3S (379.56): calcd. C 72.78, H 7.70,
N 11.07; found C 72.35, H 7.30, N 11.01.
1
52.4%. H NMR (600 MHz, CDCl3): δ = 1.50 [s, 6 H, C(CH3)2],
3
3
1.66 [s, 9 H, C(CH3)3], 2.71 (t, J = 6.6 Hz, 2 H, CH2), 3.79 (t, J
3
= 6.6 Hz, 2 H, CH2), 6.95 (m, 2 H, CH-Ph), 7.07 (t, J = 6.6 Hz,
1 H, CH-Ph), 7.14 (t, 3J = 7.2 Hz, 1 H, CH-Ph), 7.16 (t, 3J =
3
7.2 Hz, 1 H, CH-Ph), 7.34 (t, J = 7.8 Hz, 1 H, CH-Ph), 8.10 (d,
3J = 7.8 Hz, 1 H, CH-Ph), 8.41 ppm (d, 3J = 7.8 Hz, 1 H, CH-Ph).
13C{1H} NMR (150 MHz, CDCl3): δ = 21.1 [s, C(CH3)2], 30.6 [s,
C(CH3)3], 31.3 (s, CH2), 49.9 [s, C(CH3)3], 53.1 (s, CH2), 57.0 [s,
PhN=CA(CBMe2)(NBPh)CC=N(CH2)2SPh(CA–NB)(CB–CC) (3): C(CH3)2], 116.8, 120.8, 124.2, 125.1, 125.5, 129.0, 138.9 (CH-
The procedure for the preparation of 3 was similar to that used
C6H5), 130.1, 130.2, 145.5, 153.1, 158.7 ppm (one η1-Ph, two Cipso
-
1
for 2. A white solid was obtained. Yield, 0.46 g, 91.0%. H NMR
C6H5, and two C=N groups). C23H28ClN3PdS (520.43): calcd. C
53.08, H 5.42, N 8.07; found C 53.29, H 5.36, N 8.40.
(600 MHz, CDCl3): δ = 1.34 [s, 6 H, C(CH3)2], 3.19 (t, 3J = 7.2 Hz,
4646
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 4642–4648

The Synthesis and Properties of Palladacyclic Complexes
FULL PAPER
[PhN=CA(CBMe2)(NB-η1-C6H4)CC=N(CH2)2SPh(CA–NB)(CB–
CC)]PdCl (7): The procedure for the preparation of 7 was similar
to that used for 6; however, compound 5 was used instead of 4.A
yellow solid was obtained. Yield, 0.274 g, 87.0 %. 1H NMR
hydrogen atoms were located from successive difference Fourier
maps, and hydrogen atoms were refined using a riding model. An-
isotropic thermal parameters were used for all non-hydrogen atoms,
and fixed isotropic parameters were used for the hydrogen atoms.
(600 MHz, CD2Cl2): δ = 1.46 [s, 6 H, C(CH3)2], 2.99 (t, 3J = 6.0 Hz, The asymmetric unit of 4 contains a severely disordered molecule
3
2 H, CH2), 3.76 (br., 2 H, CH2), 6.97 (d, J = 7.2 Hz, 2 H, o-Ph), of dichloromethane, and a molecule of water. Crystallographic data
3
7.04 (m, 1 H, CH-Ph), 7.14 (t, J = 7.2 Hz, 1 H, CH-Ph), 7.19 (t,
collection and refinement details are given in Table 5.
3
3J = 7.2 Hz, 1 H, CH-Ph), 7.35 (t, J = 7.8 Hz, 2 H, m-Ph), 7.47
CCDC-269677 and -269678 for compounds 3 and 4 contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
(m, 3 H, CH-Ph), 8.11 (m, 2 H, CH-Ph), 8.17 (d, 3J = 8.4 Hz, 1
H, CH-Ph), 8.40 ppm (m, 1 H, CH-Ph). 13C{1H} NMR (150 MHz,
CD2Cl2): δ = 21.0 [s, C(CH3)2], 39.2 (s, CH2), 53.3 (s, CH2), 57.4
[s, C(CH3)2], 117.1, 120.9, 124.3, 124.7, 125.7, 129.2, 129.8, 130.0,
133.4, 138.9 (CH-C6H5), 129.6, 130.3, 130.7, 145.8, 153.7,
159.0 ppm (one η1-Ph, three Cipso-C6H5, and two C=N groups).
C25H24ClN3PdS (540.42): calcd. C 55.56, H 4.48, N 7.78; found C
55.47, H 4.070, N 7.80.
Acknowledgments
We would like to thank the National Science Council of the Repub-
lic of China for financial support.
General Procedure for the Suzuki-Type Coupling Reaction: Pre-
scribed amounts of catalyst, base (2.0 equiv.), boronic acid
(1.5 equiv.), and aryl halide (1.0 equiv.) were placed under nitrogen
in a Schlenk tube. Solvent (2 mL) was added by syringe, and the
reaction mixture was heated at the prescribed temperature for the
prescribed amount of time.
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3
4
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Formula
Fw
T [K]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C25H25N3S
399.54
293(2)
C26H35Cl2N3O3PdS
646.93
293(2)
monoclinic
C2/c
22.7849(14)
13.2886(8)
20.8977(13)
90
112.7370(10)
90
5835.7(6)
8
1.473
0.922
triclinic
¯
P1
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11.6307(11)
12.1069(11)
90.187(2)
98.050(2)
100.699(2)
1095.32(18)
2
2527–2572.
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γ [°]
V [Å3]
Z
ρcalc [Mg/m3]
1.211
0.163
µ(Mo-Kα) [mm–1]
Reflections collected 6263
16054
335
0.0422
0.1332
No. of parameters
262
R1[a]
0.0491
0.1452
1.065
wR2[a]
GoF[b]
1.14
[a] R1 = [Σ(|Fo| – |Fc|)/Σ |Fo2|]; wR2 = [Σw(Fo – Fc ) /Σw(Fo2)2]1/2
,
2
2 2
w = 0.10. [b] GoF = [Σw(Fo – Fc ) /(Nrflns – Nparams)]1/2
.
2 2
Eur. J. Inorg. Chem. 2006, 4642–4648
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4647

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Received: June 27, 2006
Published Online: September 22, 2006
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 4642–4648