Manganese(II), nickel(II), and palladium(II) complexes of a terpyridine-Like ligand containing a sulfur linkage, and an analogous NCN pincer palladium(II) complex: Synthesis, characterization, and Pd-Catalyzed reactions

Article abstract of DOI:10.1246/bcsj.20100076

Coordination properties of new polypyridines containing a single sulfur linkage, 6-(2″-pyridylthio)-2, 2′-bipyridine (L1) and 1-(2′-pyridyl)-3-(2″-pyridylthio)benzene (HL2), are described. The manganese(II) and nickel(II) complexes of the terpyridine-like ligand L1, [MnCl₂(L1)] (1), [NiCl(μ-Cl)(L1)]₂ (2), and [Ni(L1)₂](SbF₆)₂ (3), were prepared and characterized by UV-vis spectroscopy and X-ray crystallography. The palladium(II) complex [PdCl(L1)]Cl (4) was synthesized from L1 and Li ₂[PdCl₁] at room temperature, while the corresponding NCN pincer complex of L2, [PdCl(L2)] (5), was synthesized in DMSO at 150 °C by cyclopalladation of the ligand precursor HL2. The crystal structures of 4 and 5 revealed similar coordination geometries around Pd except for the longer Pd-Cl distance in 5, which is induced by the strong trans influence of the Pd-C bonding. The NMR spectra of 4 showed partial dissociation of L1 in DMSO-d ₆, which was not observed for L2 in 5. Catalytic activities of 4 and 5 for the Mizoroki-Heck reaction were investigated, and the lower activity of 5 can be related to the strong σ-donating character of L2.

Full text of DOI:10.1246/bcsj.20100076

1058 Bull. Chem. Soc. Jpn. Vol. 83, No. 9, 1058–1066 (2010)
© 2010 The Chemical Society of Japan
Manganese(II), Nickel(II), and Palladium(II) Complexes of
a Terpyridine-Like Ligand Containing a Sulfur Linkage,
and an Analogous NCN Pincer Palladium(II) Complex:
Synthesis, Characterization, and Pd-Catalyzed Reactions
Masakazu Hirotsu,* Yuhei Tsukahara, and Isamu Kinoshita
Department of Material Science, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585
Received March 15, 2010; E-mail: mhiro@sci.osaka-cu.ac.jp
Coordination properties of new polypyridines containing a single sulfur linkage, 6-(2¤¤-pyridylthio)-2,2¤-bipyridine
(L1) and 1-(2¤-pyridyl)-3-(2¤¤-pyridylthio)benzene (HL2), are described. The manganese(II) and nickel(II) complexes
of the terpyridine-like ligand L1, [MnCl2(L1)] (1), [NiCl(®-Cl)(L1)]2 (2), and [Ni(L1)2](SbF6)2 (3), were prepared and
characterized by UV-vis spectroscopy and X-ray crystallography. The palladium(II) complex [PdCl(L1)]Cl (4) was
synthesized from L1 and Li2[PdCl4] at room temperature, while the corresponding NCN pincer complex of L2, [PdCl(L2)]
(5), was synthesized in DMSO at 150 °C by cyclopalladation of the ligand precursor HL2. The crystal structures of 4 and 5
revealed similar coordination geometries around Pd except for the longer Pd-Cl distance in 5, which is induced by the
strong trans influence of the Pd-C bonding. The NMR spectra of 4 showed partial dissociation of L1 in DMSO-d6, which
was not observed for L2 in 5. Catalytic activities of 4 and 5 for the Mizoroki-Heck reaction were investigated, and the
lower activity of 5 can be related to the strong ·-donating character of L2.
5
4
3"
6"
3"
6"
Planar tridentate ligands based on 2,2¤:6¤,2¤¤-terpyridine
(terpy) have been widely used for transition-metal complexes
incorporated in supramolecular architecture and multicompo-
nent reaction systems.1,2 The special attention of terpyridine
metal complexes are their outstanding photophysical proper-
ties.3,4 A major advantage of terpyridine relies on the inherent
stability of its complexes, which is due to the strong coor-
dinating ability and dynamic chelate effect. Mono- and bis-
complexes of terpyridines are easily prepared under stoichio-
metric reaction conditions. Therefore various photoinduced
electron- or energy-transfer systems have been developed using
functionalized terpyridine derivatives.5
Recent studies showed that transition-metal complexes of
terpyridines are useful as catalysts. For example, a di-®-oxo
manganese complex of terpyridine catalyzes the conversion of
sodium hypochlorite to molecular oxygen.6 Catalytic cross-
coupling reactions were reported for terpyridine nickel com-
plexes.7,8 Enantioselective cyclopropanations were carried out
using copper or rhodium complexes of chiral terpyridines.9,10
To refine the steric and electronic character of the metal center
in terpyridine complexes, the three pyridine rings of terpyridine
were functionalized without changing its backbone. On the
other hand, pyridine-based pincer complexes containing
a metal-carbon bond were used in catalysis, and the palla-
dium(II) complexes with two six-membered metallacycles
showed high catalytic performance in the Mizoroki-Heck
reaction compared to the five-membered analogs.11,12 The
modification of the chelate rings size is also important for the
development of new catalytic systems.
3 S 2"
S
6
2"
4"
5"
5
6
4"
5"
4
3
N1
N
N
2
1"
2
1"
1
2'
2'
N1'
6'
N1'
3'
4'
3'
4'
6'
5'
5'
L1
HL2
Chart 1.
bipyridine (L1) and 1-(2¤-pyridyl)-3-(2¤¤-pyridylthio)benzene
(HL2) (Chart 1). The coordination properties of the N,N,N-
tridentate ligand L1 were investigated using manganese(II),
nickel(II), or palladium(II) ion. The cyclopalladation of the
ligand precursor HL2 provided a palladium(II) complex with a
N-C-N sequence of donor atoms. The palladium(II) complexes
of L1 and L2 were compared in structure, solution behavior, and
catalytic activity in the Mizoroki-Heck reaction.
Results and Discussion
Synthesis of Ligands. The pyridine-based tridentate ligand
L1 was synthesized by the reaction of 6-bromo-2,2¤-bipyridine
with pyridine-2-thiol in 1,2-propanediol (Scheme 1). Purifica-
tion by silica gel column chromatography gave a pale yellow
oil of L1 in 81% yield.
The ligand precursor HL2 for the NCN ligand was obtained
from 1,3-dibromobenzene in three steps according to
Scheme 2. Treatment of 1,3-dibromobenzene with pyridine-2-
thiol gave the monosubstituted product 1-bromo-3-(2¤-pyri-
dylthio)benzene in 31% yield after purification by column
In this paper we report a new class of polypyridines
containing a single sulfur linkage: 6-(2¤¤-pyridylthio)-2,2¤-
Published on the web August 21, 2010; doi:10.1246/bcsj.20100076

M. Hirotsu et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 9 (2010) 1059
Table 1. Selected Bond Lengths/¡ and Angles/° for 1
Br
N
S
Mn-N(1)
Mn-N(2)
Mn-N(3)
2.2440(12)
2.2756(12)
2.2414(12)
Mn-Cl(1)
Mn-Cl(2)
2.3949(4)
2.3471(4)
N
N
N
pyridine-2-thiol
1,2-propanediol
120 °C, 3 h
N
Cl(1)-Mn-Cl(2) 105.953(13) Cl(2)-Mn-N(2) 94.88(3)
Cl(1)-Mn-N(1) 93.62(3)
Cl(1)-Mn-N(2) 158.13(3)
Cl(1)-Mn-N(3) 94.72(3)
Cl(2)-Mn-N(1) 112.06(3)
Cl(2)-Mn-N(3) 116.84(3)
N(1)-Mn-N(2) 71.97(4)
N(1)-Mn-N(3) 125.58(4)
N(2)-Mn-N(3) 81.40(4)
L1
Scheme 1. Synthesis of the N,N,N-tridentate ligand L1.
C(10)-S-C(11)
101.43(6)
S
1) n-BuLi / Et2O
pyridine-2-thiol
K2CO3, DMF
reflux, 5 h
N
2) B(OMe)3
3) HCl aq.
Br
Br
Br
S
N
S
N
2-bromopyridine
[Pd(PPh3)4]
K2CO3
DME / H2O
B
N
HO
OH
HL2
Scheme 2. Synthesis of a precursor for the N,C,N-tridentate
ligand L2.
Figure 2. ORTEP drawing of 2 with thermal ellipsoids at
the 50% probability level. Hydrogen atoms are omitted for
clarity.
are 158.13(3)° of Cl(1)-Mn-N(2) and 125.58(4)° of N(1)-Mn-
N(3). The structural index parameter ¸ for 1 becomes 0.54,
where ¸ = (¢ ¹ ¡)/60 (¡ and ¢ are the two largest bond
angles around the metal ion, ¢ > ¡).13 This indicates that the
geometry around Mn is between trigonal bipyramidal and
square pyramidal. A modified index parameter, », has been
proposed to describe the trigonality of five-coordinate com-
plexes, where » = (¢ + £ + ¤ ¹ 2¡)/180 (£ and ¤ represent
the remaining bond angles around the metal ion without the
donor atoms defining ¢).14 The » value for 1 is 0.75, which
suggests that the geometry around Mn in 1 is better described
as a distorted trigonal bipyramid with the two apical positions
occupied by Cl(1) and N(2). The Mn-Cl(1) and Mn-N(2)
bonds are slightly longer than Mn-Cl(2) and Mn-N(terminal),
respectively. The corresponding manganese(II) complex of
terpyridine, [MnCl2(terpy)], was reported as a distorted square
pyramid with the NNNCl basal plane: the ¸ and » values are
0.04 and 0.34, respectively.15 Thus the trigonal-bipyramidal
structure of 1 results from the S linkage in the L1 ligand, which
is folded along the S£Mn line. The fold angle is 60.36(5)°,
which is defined as the deviation angle of the pyridine ring with
N(3) from the bipyridine plane.
Figure 1. ORTEP drawing of 1 with thermal ellipsoids at
the 50% probability level. Hydrogen atoms are omitted for
clarity.
chromatography. Bromine-lithium exchange with n-butyl-
lithium followed by the reaction with trimethyl borate and
then hydrolysis resulted in the formation of 3-(2¤-pyridyl-
thio)phenylboronic acid in 65% yield. The palladium-catalyzed
cross-coupling reaction of the boronic acid with 2-bromopyri-
dine afforded HL2 as a pale yellow solid in 85% yield.
Synthesis and Structure of Manganese(II) Complex 1.
The manganese(II) complex [MnCl2(L1)] (1) was prepared by
the reaction of MnCl2¢4H2O with an equimolar amount of L1
in ethanol. Vapor diffusion of diethyl ether into a methanol
solution of 1 gave yellow crystals, from which the crystal
structure was obtained (Figure 1). The manganese ion is
surrounded by three N donors of an L1 ligand and two chloride
ions to form a five-coordinate structure. The bond lengths and
angles around Mn are listed in Table 1. The two largest angles
Synthesis and Structures of Nickel(II) Complexes 2 and
3. Treatment of a methanol solution of NiCl2¢6H2O with L1 in
a 1:1 molar ratio gave a green solution, from which [NiCl(®-
Cl)(L1)]2 (2) was isolated as green crystals. The structure of 2
was determined by X-ray crystal structure analysis (Figure 2),
and selected bond distances and angles are listed in Table 2.
Complex 2 has a dimeric structure consisting of two NiCl2(L1)
units, in which L1 adopts meridional coordination. The Ni

1060 Bull. Chem. Soc. Jpn. Vol. 83, No. 9 (2010)
Table 2. Selected Bond Lengths/¡ and Angles/° for 2
Tridentate Ligands with a Sulfur Linkage
Ni(1)-N(1)
Ni(1)-N(2)
Ni(1)-N(3)
Ni(1)-Cl(1)
Ni(1)-Cl(3)
Ni(1)-Cl(2)
2.0746(18) Ni(2)-N(4)
2.066(2) Ni(2)-N(5)
2.0996(19) Ni(2)-N(6)
2.4254(6) Ni(2)-Cl(3)
2.4289(7) Ni(2)-Cl(1)
2.4422(7) Ni(2)-Cl(4)
2.068(2)
2.067(2)
2.0912(18)
2.4229(6)
2.4162(7)
2.4814(7)
N(1)-Ni(1)-N(2) 79.49(8)
N(2)-Ni(1)-N(3) 92.94(7)
N(4)-Ni(2)-N(5) 79.53(8)
N(5)-Ni(2)-N(6) 93.47(7)
N(1)-Ni(1)-N(3) 168.91(8) N(4)-Ni(2)-N(6) 169.33(8)
N(2)-Ni(1)-Cl(1) 171.21(6) N(5)-Ni(2)-Cl(3) 170.98(6)
Cl(1)-Ni(1)-Cl(3) 84.87(2)
Cl(2)-Ni(1)-Cl(3) 176.75(2) Cl(1)-Ni(2)-Cl(4) 176.53(2)
Ni(1)-Cl(1)-Ni(2) 95.10(2) Ni(1)-Cl(3)-Ni(2) 94.83(2)
Cl(1)-Ni(2)-Cl(3) 85.20(2)
C(10)-S(1)-C(11) 107.44(11) C(25)-S(2)-C(26) 108.03(12)
centers are doubly bridged by chloro ligands and the other two
chloride ions act as terminal ligands to form two edge-shared
N3Cl3 octahedra. The dinuclear structure has pseudo Ci
symmetry with the inversion center at the midpoint between
two Ni atoms. The Ni-N bonds from pyridylthio groups
are somewhat longer than those from bipyridine moieties:
average, Ni-N(c) = 2.067(2) ¡, Ni-N(pyC) = 2.071(2) ¡, Ni-
N(pyS) = 2.095(2) ¡; c, pyC, and pyS in parentheses denote a
central donor atom in a tridentate ligand, and terminal pyridyl
groups bound to C and S atoms, respectively. The trans angles,
N(1)-Ni(1)-N(3) and N(4)-Ni(2)-N(6) in 2 are 168.91(8) and
169.33(8)°, respectively. These structural features are different
from those of terpyridine nickel(II) complexes, which usually
show significant decreases of the Ni-N(c) bond distance and
the N-Ni-N trans angle.16-18 The meridionally coordinated L1
ligand in 2 shows deviation from planarity at the S linkage: the
fold angles between bipyridine and pyridine units are 36.66(8)
and 33.36(8)°. Although these angles are considerably smaller
than that in 1 (60.36(5)°), all the Ni-N bonds in 2 are com-
parable to those in [Ni(bpy)3]SO4 (average, 2.089(9) ¡).19
Thus, there is no significant strain in the coordination geometry
in 2 because of the flexible S linkage in L1.
Figure 3. ORTEP drawing of 3 with thermal ellipsoids at
the 50% probability level. Hexafluoroantimonate anions
and hydrogen atoms are omitted for clarity.
Table 3. Selected Bond Lengths/¡ and Angles/° for 3
Ni-N(1)
Ni-N(2)
Ni-N(3)
2.124(3)
2.068(3)
2.092(3)
Ni-N(4)
Ni-N(5)
Ni-N(6)
2.114(3)
2.064(3)
2.104(3)
N(1)-Ni-N(2)
N(2)-Ni-N(3)
N(1)-Ni-N(3)
N(2)-Ni-N(5)
76.44(14) N(4)-Ni-N(5)
93.90(14) N(5)-Ni-N(6)
169.53(14) N(4)-Ni-N(6)
166.72(15)
77.20(13)
93.42(14)
168.38(14)
C(10)-S(1)-C(11) 105.9(2)
C(25)-S(2)-C(26) 106.0(2)
S
S
N
N
Li2[PdCl4]
DMSO, 150 °C
H
Pd
N
N
Cl
The 2:1 reaction of L1 with Ni(CH3COO)2¢4H2O afforded
purple crystals of [Ni(L1)2](SbF6)2 (3) by adding NaSbF6. The
crystal structure of 3 is shown in Figure 3, and selected bond
distances and angles are given in Table 3. Two L1 ligands are
bound through three N atoms in a meridional fashion. The Ni-
N bonds from terminal N atoms in bipyridine units in 3 (Ni-
N(1) = 2.124(3) ¡, Ni-N(4) = 2.114(3) ¡) are slightly longer
than the corresponding Ni-N distances in 2 (2.0746(18) and
2.068(2) ¡). Furthermore, the fold angles of L1 (44.61(15)
and 47.34(15)°) are larger than those in 2. These results suggest
that the bis-coordination of L1 in 3 induces the repulsive
intramolecular interactions between the terminal and central
pyridine rings in different ligands. In contrast, the Ni-N
distances of terpyridine complexes are similar between mono-
and bis-complexes, which is due to the smaller intraligand
N-Ni-N trans angles reducing the steric repulsion between
ligands.16-18,20,21
HL2
[PdCl(L2)] (5)
Scheme 3. Synthesis of the palladium complex [PdCl(L2)] (5).
gave an orange suspension, from which orange crystals of
[PdCl(L1)]Cl (4) were obtained. The corresponding L2 complex
[PdCl(L2)] (5) was synthesized by heating a dimethyl sulfoxide
(DMSO) solution of the ligand precursor HL2 and Li2[PdCl4] at
150 °C (Scheme 3). In 1H NMR experiments (DMSO-d6), 70%
of HL2 was cyclopalladated to form 5 after heating at 150 °C
for 4 h and no other new signals were observed. Thus the C-H
bond between 2-pyridyl and 2-pyridylthio groups in HL2 is
selectively activated. The high regioselectivity stems from the
two pyridyl groups in HL2 since precoordination of the pyridyl
group was found to facilitate the cyclometallation.22,23
The structures of 4 and 5, which were confirmed by X-ray
structure analysis, are shown in Figures 4 and 5, respectively.
Selected bond distances and angles are summarized in Table 4.
In both complexes, the palladium ion is surrounded by a
tridentate ligand and a chloride ion to form a square-planar
Synthesis and Structures of Palladium(II) Complexes 4
and 5. Palladium complexes were synthesized for both L1 and
L2 ligands. The reaction of L1 with Li2[PdCl4] in methanol

M. Hirotsu et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 9 (2010) 1061
Table 4. Selected Bond Lengths/¡ and Angles/° of 4 and 5
4
5
Pd-N(c) or C(c)a)
Pd-N(pyC)a)
Pd-N(pyS)a)
Pd-Cl
2.0069(16) 1.9577(19)
2.0108(18) 2.0435(15)
2.0350(18) 2.0655(17)
2.2936(4)
2.4191(5)
N(c)-Pd-N(pyC)a)
N(c)-Pd-N(pyS)a)
80.83(6)
94.76(6)
80.74(7)
93.39(7)
165.69(6)
95.64(4)
171.64(5)
91.81(5)
N(pyC)-Pd-N(pyS) or N(pyC)a) 167.29(7)
N(pyC)-Pd-Cla)
N(c)-Pd-Cla)
N(pyS)-Pd-Cla)
C-S-C
94.71(4)
172.01(5)
90.95(4)
105.37(11) 105.47(9)
a) Abbreviations c, pyC, and pyS in parentheses mean a central
donor atom in a tridentate ligand, 2-pyridyl groups bound to C
and S atoms, respectively.
Figure 4. ORTEP drawing of 4 with thermal ellipsoids at
the 50% probability level. Hydrogen atoms are omitted for
clarity.
Figure 5. ORTEP drawing of 5 with thermal ellipsoids at
the 50% probability level. Hydrogen atoms are omitted for
clarity.
Figure 6. Absorption spectra of 2 in methanol (®), 3 in
acetonitrile (- - -), and L1 in methanol (- Á -).
complex, [PdCl(L1)]+ or [PdCl(L2)]. As shown in Figure 4, the
complex cations [PdCl(L1)]+ in 4 tend to pair, forming a face to
face dimer with a Pd£Pd distance of 3.5387(2) ¡. There is a
relatively short contact of 3.5448(7) ¡ between the counter ion
six-coordinate complexes 2 and 3, and smaller than that of the
five-coordinate complex 1.
The coordination geometries of 4 and 5 are compared
with those of the analogous palladium(II) complexes,
[PdCl(terpy)]Cl24 and [PdCl(LN,C,N)],11 where LN,C,N is a 2,6-
bis(2-pyridyl)phenyl ligand. The Pd-N(c) distance in 4 is
larger than that in [PdCl(terpy)]Cl (1.96(2) ¡) by ca. 0.05 ¡.
Similar elongation was observed for the Pd-C distance in 5
by comparison with [PdCl(LN,C,N)] (1.910(2) ¡). The Pd-Cl
distances are 2.313(7) ¡ for [PdCl(terpy)]Cl and 2.427(1) ¡
for [PdCl(LN,C,N)], which are similar to those for 4 and 5,
respectively. Thus the NCN pincer ligands show the elongation
of the Pd-Cl bond by ca. 0.1 ¡ compared with the correspond-
ing NNN tridentate ligands.
¹
Cl and the Pd atom. The Cl(2)£Pd£Pd*£Cl(2)* arrangement
is close to linear with a Cl(2)-Pd-Pd* angle of 174.297(11)°,
which suggests the weak bonding interactions in the axial
direction. In complex 5, L2 acts as an anionic N,C,N-tridentate
ligand, which forms a five-membered and a six-membered
metallacycle (Figure 5). There is no Pd£Pd interaction in the
crystal structure of 5, while ³-³ stacking interactions are
observed between the pyridyl ring containing N(1) and the five-
membered chelate ring with C(11) and N(1) donor atoms:
N(1)£C(5)*, C(5)£N(1)*, 3.471(2); C(6)£C(1)*, 3.422(2);
C(11)£C(2)*, 3.435(2); Pd£C(3)*, 3.753(2); Pd£C(4)*,
3.7204(19) ¡. The Pd-C distance in 5 (1.9577(19) ¡) is smaller
than the Pd-N(central) distance in 4 (2.0069(16) ¡), while the
Pd-Cl distance in 5 (2.4191(5) ¡) is larger than that in 4
(2.2936(4) ¡), indicating a strong trans influence of the carbon
donor atom in 5. Other bond distances and angles are similar
between 4 and 5. The fold angles between bipyridine (or
phenylpyridine) and pyridine units in 4 and 5 are 45.53(8) and
39.14(6)°, respectively. These values are similar to those of the
Spectroscopic Characterization of Complexes. Absorp-
tion spectra of L1, 2, and 3 are shown in Figure 6, and spectral
data for L1 and all the complexes are summarized in Table 5.
¹1
Ligand L1 exhibits intense bands above 29000 cm (below
340 nm), which are assignable to ³-³* transitions (Figure 6).
The spectrum of manganese(II) complex 1 was quite similar to
that of L1 in dilute conditions, which suggests the dissociation
of the ligand.

1062 Bull. Chem. Soc. Jpn. Vol. 83, No. 9 (2010)
Tridentate Ligands with a Sulfur Linkage
Table 5. Absorption Spectral Data for L1, 1, 2, 3, 4, and 5
¹1
Complex (solvent)
- )
max/nm (¾/mol¹1 dm3 cm
L1 (CH3OH)
1 (CH3OH)
2 (CH3OH)
3 (CH3CN)
4 (CH3OH)
5 (DMSO)
315 (8300),a) 284 (13800), 239 (17600)
316 (8100),a) 283 (13900), 239 (17600)
952 (12.6), 773 (6.21), 633 (16.2), 334 (21900), 292 (27000), 244 (30200)
870 (11.6), 795 (11.0),a) 537 (16.2), 335 (17900), 291 (23900), 245 (30000)
351 (8300), 303 (9500), 255 (18400),a) 233 (30000)
373 (2800),a) 332 (9370), 320 (9390), 275 (20400)
a) Shoulder.
Nickel(II) complexes 2 and 3 show intense bands above
¹1
27000 cm (below 370 nm), which are assignable to ³-³*
transitions localized on the ligand (Figure 6). In the visible
region,
2 displays two bands at 10500 (952 nm) and
¹1
15800 cm (633 nm), which are assignable to d-d transitions,
3T2g(F) ← 3A2g and T1g(F) ← 3A2g, respectively. The dimeric
3
structure of 2 can be dissociated to the mononuclear species
n+
such as [NiCl2¹n(L1)(CH3OH)1+n
]
(n = 0, 1, and 2) in
methanol because of the lability of the nickel(II) center.
The electrospray ionization (ESI) mass spectrum of 2 in
methanol exhibited peaks due to the [Ni(L1)(CH3OH)]2+ ion.
The absorption spectrum of 2 readily changed to that of 3 by
adding an equimolar amount of L1. The [Ni(L1)2]2+ ion was
observed in the ESI mass spectrum of 3. An acetonitrile
¹1
solution of 3 showed the absorption bands at 11500 cm
Figure 7. 1H NMR (300 MHz) spectra of (a) 4 in methanol-
d4, (b) 4 in DMSO-d6, and (c) 5 in DMSO-d6. Asterisks
denote the signals of the free ligand L1.
(870 nm) and 18600 (537 nm), which were assigned to d-d
transitions, T2g(F) ← 3A2g and T1g(F) ← 3A2g, respectively,
in a symmetry near Oh. The transition energies of these bands
are smaller than those of [Ni(terpy)2](ClO4)2 in acetonitrile
(12600 and 19400 cm¹1) and [Ni(bpy)3]Cl2 in H2O (12600 and
19300 cm¹1).20,25 The reduction in ¦O for 3 is related to the
six-membered chelate and the intramolecular repulsion of L1
found in the crystal structure.
3
3
Table 6. Mizoroki-Heck Reactions Catalyzed by Palladium
Complexes 4 and 5
CO2Me
I
Pd complex
DMF, Et3N
CO2Me
+
The absorption spectrum of palladium(II) complex 4 in
methanol was characterized by three intense bands in the
range of 220-390 nm. The absorption at 28500 cm (351 nm)
Entry
Catalyst (mol %)
T/°C
Time/h
Yield/%a)
¹1
1
2
3
4
5
6
7
8
4 (0.1)
5 (0.1)
4 (0.1)
5 (0.1)
4 (0.001)
5 (0.001)
4 (0.001)
5 (0.001)
110
110
80
5
5
5
5
5
5
15
15
>99
>99
92
6
7
6
22
20
can be attributed to a metal to ligand charge-transfer (MLCT)
transition by analogy to terpyridine palladium(II) complexes.26
The higher-energy transitions are related to intraligand ³-³*
transitions.
80
110
110
110
110
1
The H NMR spectrum of 4 showed that the L1 ligand in 4
partially dissociates in a DMSO-d6 solution at room temper-
ature (Figure 7). The ratio of 4 and L1 was 5:1, and the
complex cation [Pd(Me2SO)4]2+ would be formed.27,28 This
dissociation results from the coordination ability of DMSO
because no signal of free L1 was observed in methanol-d4. In
contrast, the L2 ligand in complex 5 is stable in DMSO as
expected from the synthesis conditions. The strong ·-donating
character of aryl C donor of L2, which forms stable metalla-
cycles, prevents the dissociation of L2 in DMSO. In the NMR
spectra of 4 and 5, two 6-positioned H signals of 2-pyridyl and
2-pyridylthio groups exhibit low field shifts compared with
those of the free ligands. This suggests that the 2-pyridylthio
group, as well as the 2-pyridyl group, is bound to Pd in the
solution.
a) Yields are given relative to iodobenzene.
iodobenzene and methyl acrylate. All reactions were performed
in N,N-dimethylformamide (DMF) in the presence of trieth-
ylamine as a base. The results are summarized in Table 6. The
reactions in Entries 1 and 2 were carried out at 110 °C for 5 h
using 4 and 5 as catalysts (0.1 mol %), respectively, and were
1
monitored by H NMR spectroscopy. Figure 8 shows the time
course of the yields of methyl trans-cinnamate. Catalysts 4 and
5 gave excellent conversions after 40 min and 3 h, respectively.
The faster rate for the reaction with 4 indicates that the
formation of the catalytically active species from 4 is faster
than that from 5. When the reactions were performed at 80 °C
for 5 h, catalyst 4 gave a good yield (92%), while 5 reduced the
yield to 6% (Entries 3 and 4). Palladium black was precipitated
Mizoroki-Heck Reaction Catalyzed by Palladium(II)
Complexes. Catalytic activities of palladium(II) complexes
4 and 5 were investigated for the Mizoroki-Heck reaction of

M. Hirotsu et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 9 (2010) 1063
compared to 4. The S-linked ligands, L1 and L2, would be
applicable as tridentate polypyridine ligands for a wide range
of transition-metal ions. Further applications of these ligands to
transition metal-catalyzed reactions are in progress.
Experimental
Materials and Instrumentation.
All reagents were
purchased from commercial sources and used as received.
6-Bromo-2,2¤-bipyridine was prepared according to literature
procedures.31 Lithium tetrachloropalladate(II) was prepared by
refluxing an aqueous solution of PdCl2 (1 equiv) and LiCl
(2 equiv) for 2 h. NMR spectra were recorded on a JEOL
Lambda 300 or a Bruker AVANCE 300 FT-NMR spectrometer
at room temperature. UV-vis spectra were measured on a
JASCO V-570 spectrometer. ESI mass spectrometry was
performed on an Applied Biosystem Mariner time-of-flight
mass spectrometer. Elemental analyses were performed by the
Analytical Research Service Center at Osaka City University
on Perkin-Elmer 240C or FISONS Instrument EA1108 ele-
mental analyzers.
Figure 8. Time course of the yields of methyl trans-
cinnamate for the Mizoroki-Heck reactions of iodobenzene
(2 mmol) and methyl acrylate (3 mmol) catalyzed by 4
(0.1 mol %, ) and 5 (0.1 mol %, ). The reactions were
performed in N,N-dimethylformamide (10 mL) at 110 °C,
using triethylamine (3 mmol) as a base.
6-(2¤¤-Pyridylthio)-2,2¤-bipyridine (L1). A suspension of
6-bromo-2,2¤-bipyridine (0.71 g, 3.0 mmol) and pyridine-2-
thiol (0.50 g, 4.5 mmol) in deoxygenated 1,2-propanediol
(15 mL) was stirred at 120 °C for 3 h under an argon
atmosphere. To the resulting bright yellow solution were added
water (50 mL) and chloroform (30 mL), followed by stirring for
1 h. The organic layer was separated, and then the aqueous
layer was extracted with chloroform (30 mL). The combined
extract and organic layer were washed with water, dried over
Na2SO4, filtered, and concentrated to dryness. The residual
orange oil was purified by column chromatography (silica
gel, 2 cm © 12 cm, n-hexane/ethyl acetate, 1:1). Ligand L1
was obtained as a pale yellow oil (0.65 g, 81%). 1H NMR
(300 MHz, CDCl3, Me4Si): ¤ 7.20 (ddd, J = 7.4, 4.9, 1.2 Hz,
1H, 5¤¤-H), 7.29 (ddd, J = 7.5, 4.8, 1.2 Hz, 1H, 5¤-H), 7.43 (dd,
J = 7.8, 0.9 Hz, 1H, 5-H), 7.54 (dt, J = 8.0, 1.1 Hz, 1H, 3¤¤-H),
7.65 (ddd, J = 8.0, 7.4, 1.9 Hz, 1H, 4¤¤-H), 7.74 (t, J = 7.8 Hz,
1H, 4-H), 7.75 (ddd, J = 8.0, 7.5, 1.8 Hz, 1H, 4¤-H), 8.26 (dt,
J = 8.0, 1.0 Hz, 1H, 3¤-H), 8.27 (dd, J = 7.8, 0.9 Hz, 1H, 3-H),
8.59 (ddd, J = 4.9, 1.9, 0.9 Hz, 1H, 6¤¤-H), 8.66 (ddd, J = 4.8,
1.8, 0.9 Hz, 1H, 6¤-H). 1H NMR (300 MHz, DMSO-d6, Me4Si):
¤ 7.36 (ddd, J = 7.5, 4.8, 1.0 Hz, 1H), 7.46 (ddd, J = 7.5, 4.8,
1.2 Hz, 1H), 7.51 (dd, J = 7.8, 0.8 Hz, 1H), 7.59 (dt, J = 8.0,
0.9 Hz, 1H), 7.84 (td, J = 7.7, 1.9 Hz, 1H), 7.92 (td, J = 7.7,
1.8 Hz, 1H), 7.93 (t, J = 7.8 Hz, 1H), 8.14 (dt, J = 7.9, 0.9 Hz,
1H), 8.27 (dd, J = 7.8, 0.8 Hz, 1H), 8.56 (ddd, J = 4.8, 1.8,
0.8 Hz, 1H), 8.69 (ddd, J = 4.8, 1.8, 0.9 Hz, 1H). 13C NMR
(75.5 MHz, CDCl3, Me4Si): ¤ 118.8 (3-C), 121.3 (3¤-C), 121.9
(5¤¤-C), 123.9 (5¤-C), 125.2 (5-C), 126.5 (3¤¤-C), 136.86 (4¤-C),
136.94 (4¤¤-C), 137.9 (4-C), 149.1 (6¤-C), 150.2 (6¤¤-C), 155.4
only in the reaction of Entry 1 (0.1 mol % of catalyst 4,
110 °C). This could be related to the solution behavior
suggested by the NMR data. Ligand L1 in 4 can dissociate in
the reaction solution, while the coordination of L2 in 5 remains
intact. Reetz and de Vries recently proposed the reaction
mechanism catalyzed by ligand-free palladium.29,30 Although
the actual catalytically active species in the reactions studied
here remain elusive, the results indicate that the strong ·-
donating character of the C donor atom in L2 prevents the
formation of active Pd(0) species from 5.
Lower catalyst loadings (0.001 mol %) significantly reduced
the yield for both 4 and 5, even when the reaction time was
extended to 15 h (Entries 5-8). The turnover frequencies were
1400 h¹1 for 4 and 1300 h¹1 for 5, which are lower than that for
¹1
the corresponding reactions using [PdCl(LN,C,N)] (5400 h
)
containing two five-membered palladacycles.11 An analogous
complex with a 2,6-bis(2-pyridyloxy)phenyl ligand has two
six-membered palladacycles, and showed higher turnover
frequencies under very dilute conditions.12 Complex 5 has a
five- and a six-membered palladacycle. The catalytic activity of
the NCN pincer Pd complexes is affected by the electronic
effect of the linkage atom, as well as the geometry around the
metal center.
Conclusion
The terpyridine-like ligand L1 containing a sulfur linkage
was isolated and used for the manganese(II), nickel(II), and
palladium(II) complexes. Five-, six-, and four-coordinate
complexes were presented for Mn, Ni, and Pd, respectively.
The fold angle between bipyridine and pyridine units varied
from 60.36(5) to 33.36(8)°. These values are indicative of
flexibility of L1 in coordination compounds.
The NCN pincer palladium(II) complex 5, which is geo-
metrically analogous to the L1-palladium(II) complex 4, was
synthesized via the regioselective C-H activation of the ligand
precursor HL2. The strong ·-donating character of the aryl
carbon donor results in the different solution behavior of 5
(2¤-C), 156.4 (2- or 6-C), 156.5 (2- or 6-C), 156.8 (2¤¤-C).
12
HRMS (ESI+): m/z calcd for
C
1H1214N332S1 ([M + H]+):
15
266.0746. Found: 266.0729.
1-Bromo-3-(2¤-pyridylthio)benzene. To a deoxygenated
solution of 1,3-dibromobenzene (4.7 g, 20 mmol) and pyridine-
2-thiol (3.3 g, 30 mmol) in DMF (80 mL) was added K2CO3
(4.1 g, 30 mmol). The reaction mixture was refluxed for 5 h
under an argon atmosphere. The resulting pale yellow suspen-
sion was filtered and concentrated to dryness. The yellow

1064 Bull. Chem. Soc. Jpn. Vol. 83, No. 9 (2010)
Tridentate Ligands with a Sulfur Linkage
residue was purified by column chromatography (silica gel,
2.5 cm © 40 cm, n-hexane/ethyl acetate, 1:1) to give a colorless
liquid (1.66 g, 31%). H NMR (300 MHz, CDCl3, Me4Si): ¤
7.70-7.80 (m, 2H), 8.07 (ddd, J = 7.7, 1.7, 1.2 Hz, 1H), 8.24
(td, J = 1.7, 0.4 Hz, 1H), 8.43 (ddd, J = 4.9, 1.9, 0.9 Hz, 1H),
8.70 (ddd, J = 4.8, 1.7, 1.1 Hz, 1H). 13C NMR (75.5 MHz,
CDCl3, Me4Si): ¤ 119.9, 120.7, 121.4, 122.6, 127.7, 130.0,
131.7, 133.4, 135.4, 136.8, 136.9, 141.0, 149.6, 149.8, 156.3,
161.4. Anal. Calcd for C16H12N2S: C, 72.70; H, 4.58; N,
1
7.00 (dt, J = 8.0, 1.0 Hz, 1H, 3¤-H), 7.05 (ddd, J = 7.5, 4.9,
1.0 Hz, 1H, 5¤-H), 7.28 (t, J = 7.9 Hz, 1H, 5-H), 7.48-7.55
(m, 3H, 4-, 6-, and 4¤-H), 7.73 (t, J = 1.8 Hz, 1H, 2-H), 8.45
(ddd, J = 4.9, 1.9, 0.9 Hz, 1H, 6¤-H). 13C NMR (75.5 MHz,
CDCl3, Me4Si): ¤ 120.5, 122.1, 123.1, 130.8, 131.9, 132.9,
10.60%. Found: C, 72.56; H, 4.50; N, 10.42%. HRMS (ESI+):
12
m/z calcd for
C
16
1H1314N232S1 ([M + H]+): 265.0794. Found:
133.6, 136.8, 136.9, 149.8, 159.9. HRMS (ESI+): m/z calcd
265.0793.
12
for
C
11
1H979Br114N132S1 ([M + H]+): 265.9634. Found:
[MnCl2(L1)] (1). A solution of L1 (67 mg, 0.25 mmol)
in ethanol (1 mL) was added to a solution of MnCl2¢4H2O
(50 mg, 0.25 mmol) in ethanol (1 mL). The reaction mixture
was stirred at room temperature for 30 min. The resulting
yellow precipitate was collected by filtration. The product was
recrystallized by vapor diffusion of diethyl ether into a
methanol solution (12 mL). Yield: 76 mg (77%). Anal. Calcd
for C15H11Cl2MnN3S: C, 46.06; H, 2.83; N, 10.74%. Found: C,
46.35; H, 2.76; N, 10.65%. A piece of crystal was used for
single-crystal X-ray structure analysis.
265.9637.
3-(2¤-Pyridylthio)phenylboronic Acid.
1-Bromo-3-(2¤-
pyridylthio)benzene (2.12 g, 8.0 mmol) was dissolved in dry
diethyl ether (40 mL) under an argon atmosphere and cooled to
¹90 °C using a liquid nitrogen/methanol bath. n-Butyllithium
(1.6 M, 1 M = 1 mol dm¹3) in n-hexane (5.5 mL, 8.8 mmol)
was added dropwise via a syringe, and the mixture was allowed
to warm to ¹40 °C for 40 min. The pale yellow suspension was
cooled to ¹80 °C, and then trimethyl borate (1.8 mL, 16 mmol)
was added. The mixture was allowed to warm to room
temperature and stirred for 10 h. To the resulting colorless
suspension, cooled to 0 °C, was added 2 M aqueous hydro-
chloric acid (30 mL), and the mixture was stirred at room
temperature for 2 h. The aqueous layer was neutralized using
K2CO3, and extracted with diethyl ether (total 200 mL). The
organic layer and extracts were combined, washed with water,
dried over Na2SO4, filtered, and concentrated to dryness. The
colorless residue was taken up in chloroform (30 mL), filtered,
washed with chloroform, and dried under reduced pressure to
give a white powder. Yield: 1.20 g (65%). 1H NMR (300 MHz,
DMSO-d6, Me4Si): ¤ 6.90 (dt, J = 8.1, 0.9 Hz, 1H, 3¤-H), 7.14
(ddd, J = 7.4, 4.8, 0.9 Hz, 1H, 5¤-H), 7.47 (t, J = 7.5 Hz, 1H,
5-H), 7.60-7.67 (m, 2H, 4- or 6-H), 7.89 (dt, J = 7.4, 1.1 Hz,
1H, 4- or 6-H), 8.00 (s, 1H, 2-H), 8.23 (s, br, 2H, BOH), 8.40
(ddd, J = 4.8, 1.8, 0.8 Hz, 1H, 6¤-H). 13C NMR (75.5 MHz,
DMSO-d6, Me4Si): ¤ 120.2, 120.7, 129.0, 129.1, 134.9, 136.4,
137.3, 140.4, 149.4, 160.3. Anal. Calcd for C11H10BNO2S: C,
[NiCl(®-Cl)(L1)]2 (2). A solution of L1 (67 mg, 0.25 mmol)
in methanol (1 mL) was added to a solution of NiCl2¢6H2O
(60 mg, 0.25 mmol) in methanol (1 mL). The solution was
stirred at room temperature for 30 min to give a green solution.
Green crystals were grown by vapor diffusion of diethyl ether
into the methanol solution. The crystals were collected by
filtration, washed with methanol/diethyl ether (1:1), and air-
dried. Pure crystals of 2 were obtained by recrystallization
from methanol/diethyl ether. Yield: 70 mg (63%). Anal. Calcd
for C30H22Cl4N6Ni2S2¢CH3OH¢3H2O: C, 42.51; H, 3.68; N,
9.59%. Found: C, 42.39; H, 3.69; N, 9.76%. MS (ESI+):
m/z = 177.51 ([Ni(L1)(CH3OH)]2+). A piece of crystal, the
formula of which is [NiCl(®-Cl)(L1)]2¢3CH3OH, was used for
single-crystal X-ray structure analysis.
[Ni(L1)2](SbF6)2 (3). To a solution of L1 (60 mg, 0.23
mmol) in methanol (10 mL) was added Ni(CH3COO)2¢4H2O
(28 mg, 0.11 mmol), and the solution was stirred at room tem-
perature for 30 min. A solution of NaSbF6 (0.11 g, 0.43 mmol)
in methanol (2 mL) was added to the reaction solution. After
stirring for 30 min, a pink precipitate was collected by filtration.
The product was dissolved in DMSO (2 mL) and layered with
water. After two weeks purple crystals of 3 were deposited,
collected by filtration, washed with water, and air-dried. Yield:
67 mg (56%). Anal. Calcd for C30H22F12N6NiS2Sb2: C, 33.96;
H, 2.09; N, 7.92%. Found: C, 33.88; H, 2.24; N, 7.90%. MS
(ESI+): m/z = 294.04 ([Ni(L1)2]2+). A piece of crystal was
used for single-crystal X-ray structure analysis.
57.17; H, 4.36; N, 6.06%. Found: C, 57.21; H, 4.46; N, 5.85%.
12
HRMS (ESI+): m/z calcd for
C
11
1H1111B114N116O232S1
([M + H]+): 232.0600. Found: 232.0612.
1-(2¤-Pyridyl)-3-(2¤¤-pyridylthio)benzene (HL2). A solu-
tion of K2CO3 (0.55 g, 4.0 mmol) and 2-bromopyridine (0.32 g,
2.0 mmol) in 1,2-dimethoxyethane/H2O (3:1, 40 mL) was
deoxygenated by bubbling with argon gas. 3-(2¤-Pyridylthio)-
phenylboronic acid (0.46 g, 2.0 mmol) and [Pd(PPh3)4] (23 mg,
0.020 mmol) were added, and the mixture was refluxed for 6 h
under argon. To the resulting yellow solution were added
chloroform (15 mL) and water (15 mL), followed by stirring for
1 h. The organic and aqueous layers were separated, and the
aqueous layer was extracted with chloroform (15 mL). The
combined extract and organic layer were washed with water,
dried over Na2SO4, filtered, and concentrated to dryness. The
residual yellow oil was purified by column chromatography
(silica gel, 2 cm © 12 cm, n-hexane/ethyl acetate, 1:1). The
ligand HL2 was obtained as a pale yellow solid (0.45 g,
85%). 1H NMR (300 MHz, CDCl3, Me4Si): ¤ 6.94 (dt, J = 8.1,
0.9 Hz, 1H), 7.00 (ddd, J = 7.5, 4.9, 1.0 Hz, 1H), 7.26 (ddd,
J = 6.7, 4.8, 1.9 Hz, 1H), 7.45 (ddd, J = 8.1, 7.5, 1.9 Hz, 1H),
7.54 (t, J = 7.7 Hz, 1H), 7.65 (ddd, J = 7.7, 1.7, 1.3 Hz, 1H),
[PdCl(L1)]Cl (4).
To a methanol solution (4 mL) of
Li2[PdCl4] (60 mg, 0.23 mmol) was added L1 (60 mg, 0.23
mmol) in methanol (4 mL). The resulting orange suspension
was stirred at room temperature for 2 days and then filtered.
Diethyl ether was diffused into the pale orange filtrate to give
pale orange crystals, which were collected by filtration, washed
with diethyl ether, and dried under reduced pressure. Yield:
49 mg (47%). 1H NMR (300 MHz, CD3OD, Me4Si): ¤ 7.58
(ddd, J = 6.7, 6.0, 2.4 Hz, 1H, 5¤¤-H), 7.77 (ddd, J = 7.6, 5.8,
1.4 Hz, 1H, 5¤-H), 8.09-8.19 (m, 3H), 8.36 (t, J = 8.0 Hz, 1H,
4-H), 8.38 (td, J = 7.9, 1.5 Hz, 1H, 4¤-H), 8.50 (dd, J = 8.0,
1.2 Hz, 1H, 3-H), 8.54 (ddd, J = 8.2, 1.4, 0.5 Hz, 1H, 3¤-H),
9.34 (ddd, J = 5.8, 1.5, 0.5 Hz, 1H, 6¤-H), 9.48 (ddd, J = 6.0,

M. Hirotsu et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 9 (2010) 1065
Table 7. Crystallographic Data for 1, 2, 3, 4, and 5
1
2
3
4
5
Empirical formula
Formula weight
Temperature/K
Wavelength/¡
Crystal system
Space group
a/¡
b/¡
c/¡
¡/°
C15H11Cl2MnN3S
391.18
193
0.7107
monoclinic
P21/n
7.5467(10)
12.2142(17)
16.981(2)
90
C33H34Cl4N6Ni2O3S2 C30H22F12N6NiS2Sb2 C15H13Cl2N3OPdS C16H11ClN2PdS
886
113
1060.84
193
460.65
153
405.19
153
0.7107
monoclinic
P21/n
18.499(5)
9.355(2)
21.252(5)
90
0.7107
orthorhombic
Pbca
14.0794(7)
19.2201(8)
26.1610(11)
90
0.7107
monoclinic
C2/c
18.325(3)
15.056(2)
12.6184(19)
90
0.7107
monoclinic
P21/n
9.9901(14)
11.3175(14)
12.9530(19)
90
¢/°
£/°
V/¡3
91.804(3)
90
1564.5(4)
4
1.661
1.315
100.877(3)
90
3611.8(16)
4
1.629
1.498
90
90
7079.4(5)
8
1.991
106.757(3)
90
3333.7(9)
8
1.835
1.565
106.859(3)
90
1401.6(3)
4
1.92
1.656
Z
¹3
D
calcd/Mg m
¹1
®(Mo K¡)/mm
F(000)
Crystal size/mm3
2.254
4112
788
1816
1824
800
0.24 © 0.20 © 0.10 0.23 © 0.16 © 0.07 0.31 © 0.09 © 0.06 0.17 © 0.05 © 0.05 0.20 © 0.11 © 0.07
14262 26344 51670 15286 12287
Reflections collected
Independent reflections
Completeness to ª
3498 (Rint = 0.025) 8013 (Rint = 0.026) 7970 (Rint = 0.030) 3735 (Rint = 0.027) 3066 (Rint = 0.025)
97.5% (ª = 27.48°) 96.9% (ª = 27.48°) 98.3% (ª = 27.48°) 97.6% (ª = 27.48°) 95.4% (ª = 27.48°)
Max. and min. transmission
No. of data/restraints/params
Goodness of fit on F2
Final R indices [I > 2·(I)]
R indices (all data)
0.877 and 0.729
3498/0/243
1.004
R1 = 0.0231
wR2 = 0.0590
) 0.35 and ¹0.33
0.900 and 0.681
8013/22/473
1.004
R1 = 0.0455
wR2 = 0.1779
1.33 and ¹1.00
0.873 and 0.628
7970/22/500
1.004
R1 = 0.0547
wR2 = 0.2011
2.51 and ¹1.32
0.925 and 0.787
3735/11/228
1.001
R1 = 0.0248
wR2 = 0.0671
0.97 and ¹0.74
0.891 and 0.679
3066/0/234
1.017
R1 = 0.0243
wR2 = 0.0678
0.92 and ¹0.60
¹3
Largest diff. peak and hole (e ¡
1.4, 0.7 Hz, 1H, 6¤¤-H). 13C NMR (75.5 MHz, CD3OD, Me4Si):
¤ 124.4 (3-C), 125.96 (3¤-C), 126.01 (5¤¤-C), 128.5 (5¤-C),
129.3 (5-C), 129.5 (3¤¤-C), 142.7 (4¤¤-C), 143.4 (4¤-C), 144.1
(4-C), 151.4 (2¤¤-C), 152.1 (2- or 6-C), 153.9 (6¤-C), 158.5
(6¤¤-C), 158.8 (2¤-C), 160.2 (2- or 6-C). Anal. Calcd for
C15H11Cl2N3PdS¢H2O: C, 39.11; H, 2.84; N, 9.12%. Found:
C, 39.15; H, 2.76; N, 8.93%. MS (ESI+): m/z = 407.95
([Pd(L1)Cl]+), 387.98 ([Pd(L1)(OH)]+). A piece of crystal was
used for single-crystal X-ray structure analysis.
[PdCl(L2)] (5). Li2[PdCl4] (30 mg, 0.11 mmol) and HL2
(30 mg, 0.11 mmol) were dissolved in DMSO (3 mL). The
brown solution was heated at 150 °C for 14 h. The resulting
bright yellow solution, cooled to room temperature, was
filtered. The filtrate was layered with water (5 mL) and allowed
to stand at room temperature for 3 days. Pale yellow crystals of
5 were deposited, collected by filtration, washed with water,
and air-dried. Yield: 25 mg (54%). 1H NMR (300 MHz,
DMSO-d6, Me4Si): ¤ 7.26 (t, J = 7.6 Hz, 1H, 5-H), 7.36 (dd,
J = 7.7, 1.3 Hz, 1H, 4-H), 7.43 (td, J = 5.9, 3.1 Hz, 1H, 5¤¤-H),
7.48 (td, J = 5.8, 3.1 Hz, 1H, 5¤-H), 7.76 (dd, J = 7.6, 1.3 Hz,
1H, 6-H), 7.96-8.04 (m, 2H, 3¤¤- and 4¤¤-H), 8.09-8.17 (m,
2H, 3¤- and 4¤-H), 9.43 (m, 1H, 6¤-H), 9.74 (m, 1H, 6¤¤-H).
13C NMR (75.5 MHz, DMSO-d6, Me4Si): ¤ 119.9 (3¤-C),
121.6 (5¤¤-C), 123.2 (6-C), 123.4 (5¤-C), 125.3 (3¤¤-C), 126.13
(4- or 5-C), 126.17 (4- or 5-C), 128.9 (1- or 3-C), 139.0 (4¤¤-C),
140.2 (4¤-C), 146.5 (1- or 3-C), 151.9 (6¤-C), 152.8 (C-Pd),
153.4 (2¤¤-C), 156.6 (6¤¤-C), 164.2 (2¤-C). Anal. Calcd for
C16H11ClN2PdS: C, 47.43; H, 2.74; N, 6.91%. Found: C, 47.30;
H, 2.67; N, 6.70%. A piece of crystal was used for single-
crystal X-ray structure analysis.
General Procedure of Mizoroki-Heck Reaction. Iodo-
benzene (408 mg, 2.0 mmol), methyl acrylate (258 mg, 3.0
mmol), triethylamine (304 mg, 3.0 mmol), and mesitylene
(240 mg, 2.0 mmol) as an internal standard were dissolved in
DMF (10 mL) containing an appropriate amount of the isolated
complex 4 or 5. The solution was heated at 110 °C for 5 h. To
determine the yield of methyl trans-cinnamate, 0.05 mL of the
reaction solution was used for the H NMR measurements in
CDCl3. The 1H NMR spectrum of methyl trans-cinnamate was
identical to that of an authentic sample.
X-ray Crystal Structure Determination of 1, 2, 3, 4, and
5. A single crystal of 1, 2, 3, 4, or 5 was mounted on a glass
fiber. The diffraction data were collected on an AFC7/CCD
Mercury diffractometer using the rotation method with 0.5°
frame width and with 10 s exposure time per frame. The data
were processed and corrected for Lorentz and polarization
effects using CrystalClear software.32 The analyses were
carried out using the CrystalStructure 3.8 crystallographic
software package.33 Absorption corrections were applied using
the Multi Scan method. The structures were solved using direct
methods (SIR9734) and refined by full-matrix least-squares on
F2 using CRYSTALS.35 Crystallographic data are summarized
in Table 7. All non-hydrogen atoms were refined anisotropi-
cally. Hydrogen atoms in 1 and 5 were found in difference
Fourier maps and refined isotropically. Hydrogen atoms in 2, 3,
and 4 were located on calculated positions and refined as the
riding model.
1
Crystallographic data have been deposited with Cambridge
Crystallographic Data Centre: Deposition numbers CCDC-
750358, -750359, -750360, -750361, and -750362 for com-

1066 Bull. Chem. Soc. Jpn. Vol. 83, No. 9 (2010)
Tridentate Ligands with a Sulfur Linkage
14 T. Konno, K. Tokuda, J. Sakurai, K. Okamoto, Bull. Chem.
Soc. Jpn. 2000, 73, 2767.
pounds 1, 2, 3, 4, and 5, respectively. Copies of the data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html (or from the Cambridge Crystallographic Data
Centre, 12, Union Road, Cambridge, CB2 1EZ, U.K.; Fax:
+44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
15 C. Mantel, C. Baffert, I. Romero, A. Deronzier, J. Pécaut,
M.-N. Collomb, C. Duboc, Inorg. Chem. 2004, 43, 6455.
16 R. Cortés, M. I. Arriortua, T. Rojo, X. Solans, C.
Miravitlles, D. Beltran, Acta Crystallogr., Sect. C 1985, 41, 1733.
17 T. Rojo, R. Cortés, L. Lezama, M. I. Arriortua, K. Urtiaga,
G. Villeneuve, J. Chem. Soc., Dalton Trans. 1991, 1779.
18 M. G. Barandika, R. Cortés, L. Lezama, M. K. Urtiaga,
M. I. Arriortua, T. Rojo, J. Chem. Soc., Dalton Trans. 1999, 2971.
19 A. Wada, N. Sakabe, J. Tanaka, Acta Crystallogr., Sect. B
1976, 32, 1121.
This work was supported by a Grant-in-Aid for Scientific
Research (No. 18350033) from the Ministry of Education,
Culture, Sports, Science and Technology of Japan.
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