Synthesis, structural studies, and catalytic application of palladium complexes containing anilido-oxazolinate ligands

Article abstract of DOI:10.1002/ejic.201100743

A series of palladium anilido-oxazolinate complexes 1-8 prepared from ligand precursors HNArOxa [ortho-C₆H₄(NHAr)(4,4-dimethyl- 2-oxazoline) where Ar = 2,4,6-trimethylphenyl, HNPh^TriMeOxa; 2,6-diisopropylphenyl, HNPh^DiiPrOxa; phenyl, HNPh^HOxa; 2-methoxyphenyl, HNPh^OMeOxa; 2-methylthiophenyl, HNPh ^SMeOxa] is reported. Treatment of HNArOxawith 1.1 equiv. Pd(OAc) ₂ afforded palladium(II) acetate complexes (NPh^TriMeOxa) Pd(I·²-OAc) (1) and (NPh^DiiPrOxa) Pd(I·²-OAc) (2) as monomeric complexes, [(NPh ^HOxa)Pd(OAc)]₂ (3) as an anilido-bridged dinuclear complex, [(NPh^OMeOxa)Pd(OAc)]₂ (4) as an acetate-bridged dinuclear complex, and (NPh^SMeOxa)Pd(OAc) (5) as a monomeric complex. The reactions of 2, 4, and 5 with an excess of NaCl_(aq.) in acetone yielded palladium(II) chloride complexes, [(NPh^DiiPrOxa)Pd(Cl)] ₂ (6) as a chloro-bridged dinuclear complex, (NPh^OMeOxa) Pd(Cl) (7) as a monomeric complex, [(NPh^OMeOxa)Pd(Cl)]₂ (7′) as an anilido-bridged dinuclear complex, and (NPh^SMeOxa) Pd(Cl) (8) as a monomeric complex. The crystal and molecular structures of 1-8 are reported, and their application towards Suzuki and Heck reactions with a wide range of aryl halides has been examined. Copyright

Full text of DOI:10.1002/ejic.201100743

FULL PAPER
DOI: 10.1002/ejic.201100743
Synthesis, Structural Studies, and Catalytic Application of Palladium
Complexes Containing Anilido-Oxazolinate Ligands
Kuo-Fu Peng[a] and Chi-Tien Chen*[a]
Keywords: Palladium / Bidentate ligands / N ligands / Cross-coupling
A series of palladium anilido-oxazolinate complexes 1–8 pre- complex, and (NPhSMeOxa)Pd(OAc) (5) as a monomeric com-
pared from ligand precursors HNArOxa [ortho-C6H4(NHAr)-
(4,4-dimethyl-2-oxazoline) where Ar = 2,4,6-trimethylphenyl,
HNPhTriMeOxa; 2,6-diisopropylphenyl, HNPhDiiPrOxa; phen-
yl, HNPhHOxa; 2-methoxyphenyl, HNPhOMeOxa; 2-methyl-
plex. The reactions of 2, 4, and 5 with an excess of NaCl(aq.) in
acetone yielded palladium(II) chloride complexes, [(NPhDiiPr
Oxa)Pd(Cl)]2 (6) as a chloro-bridged dinuclear complex,
(NPhOMeOxa)Pd(Cl) (7) as a monomeric complex, [(NPhOMe
-
-
thiophenyl, HNPhSMeOxa] is reported. Treatment of HNArOxa Oxa)Pd(Cl)]2 (7Ј) as an anilido-bridged dinuclear complex,
with 1.1 equiv. Pd(OAc)2 afforded palladium(II) acetate com-
plexes (NPhTriMeOxa)Pd(η2-OAc) (1) and (NPhDiiPrOxa)-
Pd(η2-OAc) (2) as monomeric complexes, [(NPhHOxa)-
Pd(OAc)]2 (3) as an anilido-bridged dinuclear complex,
[(NPhOMeOxa)Pd(OAc)]2 (4) as an acetate-bridged dinuclear
and (NPhSMeOxa)Pd(Cl) (8) as a monomeric complex. The
crystal and molecular structures of 1–8 are reported, and their
application towards Suzuki and Heck reactions with a wide
range of aryl halides has been examined.
to the palladium center. However, their catalytic activities
have been less investigated.[1u–1z,2a–2e,2g,3b,3c,4a,5f] In our pre-
vious study, palladacycles bearing the pendant oxazolinate
group exhibited better activities for Suzuki and Heck reac-
tions than those with pendant pyridine or amine groups.[5d]
Recently, zinc, aluminium, and magnesium complexes con-
taining anilido-oxazolinate ligands have demonstrated ef-
ficient activities for the ring-opening polymerization of l-
lactide and ε-caprolactone.[5g–5i] Therefore, palladium com-
plexes bearing anilido-oxazolinate ligands, which are ex-
pected to have enhanced catalytic activities, have been ex-
plored. Due to the various bonding modes of the related
bidentate ligands I–IV, structural studies of these new palla-
dium complexes are reported. In order to investigate the
Introduction
Monoanionic, nitrogen-based, bidentate ligands have at-
tracted considerable attention in coordination and organo-
metallic chemistry. Among these studies, β-diketiminates
(Scheme 1, I) rapidly became benchmark ancillary li-
gands.[1a] Because of the relative ease of synthesis and the
ability to tune the steric and electronic properties through
the substitution of nitrogen or carbon atoms of the back-
bone, they work as ancillary ligands for a large number of
main group and transition metals.[1] The impact of the li-
gand skeleton I is further demonstrated through the devel-
opment of various ligand platforms, i.e. triazapentadienates
(II),[2] formazanates (III),[3] and anilidoiminates (IV).[4] An-
ilido-oxazolinates (V), which originate from IV through the
replacement of the imine group with the isoelectronic ox-
azolinate group, have received less attention.[5] Metal com-
plexes bearing I–V as ancillary ligands have been studied
and have demonstrated excellent catalytic activities in hy-
drogenation,[1c] hydrosilylation,[1d] hydroamination,[1e] cycli-
zation,[1f] oxidation,[2l,4b] cross-coupling,[2f,5c–5e] cycloalkene
oxide/CO2 copolymerization,[1g,4c,5a] olefin polymeriza-
tion,[1h–1l,3e,4d–4i] and ring-opening polymerization of cyclic
esters.[1m–1o,4j–4m,5g–5i] Recently, some palladium complexes
bearing I,[1j,1k,1u–1z] II,[2a–2g] III,[3b,3c] IV,[4a,4g] and V[5c–5f]
have been synthesized and fully characterized. These li-
gands showed various bonding modes upon coordination
[a] Department of Chemistry, National Chung Hsing University,
Taichung 402, Taiwan
E-mail: ctchen@dragon.nchu.edu.tw
Scheme 1. β-Diketiminate I and analogues II–V.
5182
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Eur. J. Inorg. Chem. 2011, 5182–5195

Palladium Complexes Containing Anilido-Oxazolinate Ligands
enhancement of catalytic activities caused by the introduc- as a purple solid. Reaction of HNPhSMeOxa with Pd(OAc)2
tion of the oxazolinate group, the catalytic application of
1–8 towards cross-coupling reactions has been examined.
in CH2Cl2 at room temperature afforded 5 as a purple solid.
The synthesis and proposed structures of 1–5 are shown in
Scheme 2. With the exception of 3, these complexes were
characterized by single-crystal X-ray diffraction, NMR
spectroscopy, and elemental analysis. The disappearance of
the N–H signal of the ligand precursors and the appearance
of the resonance for protons of the acetate groups (1.74 for
1, 1.70 for 2, 1.26 for 4, and 1.99 ppm for 5) in the up-field
region are consistent with the formation of palladium anil-
ido-oxazolinate acetate complexes. Based on the molecular
structures and NMR spectroscopic studies, the chemical
shifts of the acetate groups were used as a reference for the
different bonding modes (η2-OAc for 1 and 2, μ-OAc for 4,
and η1-OAc for 5). Because of its poor solubility in organic
solvents, 3 was characterized by single-crystal X-ray diffrac-
tion, elemental analysis, and MS.
Results and Discussion
Synthesis and Characterization of Acetate-Containing
Palladium Complexes 1–5
Ligand precursors HNPhTriMeOxa, HNPhDiiPrOxa,
HNPhHOxa, HNPhOMeOxa, and HNPhSMeOxa were pre-
pared as described previously.[5g,5h] Treatment of
HNPhTriMeOxa and HNPhDiiPrOxa with Pd(OAc)2 in hot
tetrahydrofuran (THF) afforded 1 and 2 as dark green sol-
ids, respectively. Reaction of HNPhHOxa with Pd(OAc)2 in
toluene at 50 °C yielded 3 as an orange solid. Treatment of
HNPhOMeOxa with Pd(OAc)2 in CHCl3 at 60 °C afforded 4
Scheme 2. Synthesis of palladium anilido-oxazolinate complexes 1–8.
Eur. J. Inorg. Chem. 2011, 5182–5195
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5183

K.-F. Peng, C.-T. Chen
FULL PAPER
Suitable crystals for the structural determination of 1 and ing
η2-acetate
groups
[Pd–Cacetate
2.461(5)–
2 were obtained from concentrated n-hexane solutions. The 2.509(5) Å].[1k,1w,7] The Pd–Oacteate bond lengths [2.0814(17)
molecular structures of 1 and 2 are shown in Figures 1 and and 2.0957(17) for 1, 2.0830(18) and 2.0941(16) Å for 2]
2. The summation of the bond angles (359.91° for 1 and and
Oacetate–Pd–Oacetate bite angles [62.41(7)° for 1,
360° for 2) around Pd in each compound indicates a slightly 62.61(7)° for 2] are close to those found in palladium com-
distorted square-planar geometry, in which the Pd center is plexes containing η2-acetate groups [Pd–Oacteate 2.089(4)–
coordinated to two nitrogen atoms from the chelating anil- 2.2591(14) Å;
O
acetate–Pd–Oacetate
59.92(14)–
ido-oxazolinate ligand and two oxygen atoms from the η2- 62.141(15)°].[1k,1w,7] Although most of the six-membered
acetate group. Unlike most acetate-bridged dinuclear palla- chelate rings of palladium β-diketiminate complexes adopt
dium complexes, 1 and 2 are mononuclear complexes with a half-chair or boat conformation,[1u,1v,1x,1y] the chelate
a η2-acetate ligand. This might result from the steric hin- rings of the palladium anilido-oxazolinate complexes are
drance of the substituents on the anilido groups.[1k,1w] The planar as evidenced by the dihedral angles between the pla-
Pd–Noxazoline [1.972(2) for 1, 1.974(2) Å for 2] and Pd– nes defined by N(1)–Pd–N(2)/C(1)–C(6)–C(16), which is
Nanilido bonds [1.9578(19) for 1, 1.9675(19) Å for 2] are 6.3° for 1, and N(1)–Pd–N(2)/C(1)–C(6)–C(19), which is
shorter than those found in structurally related palladium 1.6° for 2, and this conformation is consistent with other
anilido-oxazolinate complexes [Pd–Noxazoline 2.0254(14)– palladium β-diketiminate complexes.[1k,1u]
2.0731(13) Å; Pd–Nanilido 1.9942(13)–2.0077(14) Å][5c,5f]
and close to those found in palladium β-diketiminate
complexes [Pd–N 1.958(4)–2.1113(7) Å][1j,1k,1u–1z] and palla-
dium anilidoiminate complexes [Pd–Nimine 1.931–
2.086(2) Å;
Pd–Nanilido
1.938(3)–2.109(3) Å].[6]
The
N
oxazoline–Pd–Nanilido bite angles [90.55(8)° for 1, 90.17(7)°
for 2] are close to those found in palladium anilido-
oxazolinate complexes [Noxazoline–Pd–Nanilido 88.70(5)–
90.01(6)°],[5c,5f] palladium anilidoiminate complexes
[Nimine–Pd–Nanilido 82.4(4)–93.1°],[6] and palladium β-diket-
iminate complexes [N–Pd–N 87.4(1)–93.74(8)°].[1j,1k,1u–1z]
The Pd–Cacetate distances [2.434 for 1; 2.434 Å for 2] are
shorter than those found in palladium complexes contain-
Figure 2. Molecular structure of 2. Selected bond lengths [Å] and
angles (°): Pd–N(1) 1.974(2); Pd–N(2) 1.9675(19); Pd–O(2)
2.0941(16); Pd–O(3) 2.0830(18); Pd···C(24) 2.434; N(1)–Pd–N(2)
90.17(7); O(2)–Pd–O(3) 62.61(7); N(1)–Pd–O(2) 105.29(7); N(2)–
Pd–O(3) 101.93(6); N(1)–Pd–O(3) 167.90(8); N(2)–Pd–O(2)
164.51(6); O(2)–C(24)–O(3) 118.2(2); Pd–O(2)–C(24) 89.42(14).
Hydrogen atoms on carbon atoms are omitted for clarity.
Suitable crystals for the structural determination of 3
were obtained from a toluene/n-hexane solution at room
temperature. The molecular structure of 3 is depicted in
Figure 3. Although several anilido-bridged palladium com-
plexes (type VI) have been reported,[8] as shown in
Scheme 3, examples of a bridged donor atom linked to ter-
minal ligand (type VII) are relatively rare.[9] Based on its
molecular structure, 3 is a type-VII palladium complex, in
which each palladium center is coordinated to three nitro-
gen atoms (two from the same anilido-oxazolinate ligand
and one from the second anilido-oxazolinate ligand) and
one oxygen atom from η1-acetate. The Pd–Noxazoline [Pd–
N(1) 2.034(2) Å] and Pd–OAc bond lengths [Pd–O(2)
2.0328(16) Å] are similar to those discussed above. The Pd–
Nanilido bond lengths [Pd–N(2) 2.068(2) and Pd–N(2A)
2.0494(19) Å] are between type VI [2.047(2)–2.148(6) Å]
Figure 1. Molecular structure of 1. Selected bond lengths [Å] and
angles (°): Pd–N(1) 1.972(2); Pd–N(2) 1.9578(19); Pd–O(2)
2.0814(17); Pd–O(3) 2.0957(17); Pd···C(21) 2.434; N(1)–Pd–N(2)
90.55(8); O(2)–Pd–O(3) 62.41(7); N(1)–Pd–O(3) 104.84(8); N(2)–
Pd–O(2) 102.19(8); N(1)–Pd–O(2) 167.10(8); N(2)–Pd–O(3)
164.60(8); O(2)–C(21)–O(3) 118.1(2); Pd–O(2)–C(21) 90.13(15).
Hydrogen atoms on carbon atoms are omitted for clarity.
5184
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 5182–5195

Palladium Complexes Containing Anilido-Oxazolinate Ligands
and type VII [2.037(2)–2.054(2) Å] complexes. The structure. The overall dimeric structure is similar to those
N
oxazoline–Pd–Nanilido
bite
angles
[N(1)–Pd–N(2A) found in the literature.[1w,1x,10] The Pd–Noxazoline [Pd–N(1)
87.42(8)°] are smaller than those discussed above. This 2.0004(18) Å] and Pd–Nanilido bond lengths [Pd–N(2)
might result from the twist of the ligand backbone to fit 1.9855(17) Å] and the Noxazoline–Pd–Nanilido bite angle
the square-planar geometry. The distance between the two [N(1)–Pd–N(2) 89.84(7)°] are close to those discussed above
palladium centers [Pd···PdA 3.0419(4) Å] is between the for palladium β-diketiminate complexes.[1j,1k,1u–1z] The Pd–
range of type VI [3.0554(4)–3.1099(4) Å] and type VII Oacetate bond lengths [Pd–O(2) 2.0649(15) Å and Pd–O(3)
[2.875 Å] complexes. Unlike 1 and 2, the distorted six-mem- 2.0668(15) Å] are slightly longer than those found in dinu-
bered chelate ring of 3 is characterized by the dihedral angle clear acetate-bridged palladium β-diketiminate complexes
N(1)–Pd–N(2A)/C(1)–C(6)–C(14) of 43.3°.
[Pd–Oacetate 2.042(2)–2.062(2) Å].[1w,1x] Based on the van
der Waals radii, there is no bond between the palladium ion
and the oxygen atom from the methoxy group [Pd···O(4)
3.287 Å] in the solid state. The Oacetate–Pd–Oacetate bond an-
gle [O(2)–Pd–O(3) 85.63(6)°] is close to those found in dinu-
clear acetate-bridged palladium β-diketiminate complexes
[Oacetate–Pd–Oacetate 85.7(1)–88.39(9)°].[1w,1x] Similar to 3,
the distorted six-membered chelate ring of 4 is charac-
terized by the dihedral angle N(1)–Pd–N(2)/C(1)–C(6)–
C(14) of 35.6°.
Figure 3. Molecular structure of 3. Selected bond lengths [Å] and
angles (°): Pd–N(1) 2.034(2); Pd–N(2) 2.068(2); Pd–N(2A)
2.0494(19); Pd–O(2) 2.0328(16); Pd···PdA, 3.0419(4); N(1)–Pd–
N(2A) 87.42(8); N(2)–Pd–N(2A) 84.75(8); N(1)–Pd–N(2)
172.16(8); N(2A)–Pd–O(2) 175.96(7); Pd–N(2)–PdA, 95.25(8). Hy-
drogen atoms on carbon atoms are omitted for clarity.
Figure 4. Molecular structure of 4. Selected bond lengths [Å] and
angles (°): Pd–N(1) 2.0004(18), Pd–N(2) 1.9855(17), Pd–O(2)
2.0649(15), Pd–O(3) 2.0668(15), Pd···PdA 3.0138(4), N(1)–Pd–N(2)
89.84(7), O(2)–Pd–O(3) 85.63(6), N(2)–Pd–O(3) 89.23(7), N(1)–
Pd–O(2) 95.82(7), N(1)–Pd–O(3) 176.78(7), N(2)–Pd–O(2)
Scheme 3. The classes of anilido-bridged dinuclear palladium com-
plexes.
Suitable crystals for the structural determination of 4
were obtained from a concentrated CH2Cl2/n-hexane solu-
tion. The molecular structure of 4 is depicted in Figure 4.
Because of the less bulky substituent on the anilido group
than that of 1 and 2, 4 is a dinuclear species with two bridg-
168.56(7),
O(2)–C(19)–O(3A)
127.02(19),
Pd–O(2)–C(19)
126.28(14). Hydrogen atoms on carbon atoms are omitted for clar-
ity.
Suitable crystals for the structural determination of 5
ing acetate ligands. Each palladium ion adopts as a slightly were obtained from a CH2Cl2/n-hexane solution, and the
distorted square-planar geometry with two nitrogen atoms molecular structure is shown in Figure 5. As discussed
from the chelating anilido-oxazolinate ligand and two oxy- above, palladium complexes bearing anilido-oxazolinate li-
gen atoms from the bridging acetate ligands. As mentioned gands prefer to form a square-planar geometry with the
above, only one signal corresponding to the acetate ligand stabilization of η2-OAc or bridged-OAc groups. Therefore,
1
is observed in the H NMR spectrum, which indicates an the introduction of a side arm containing a soft donor atom
anti configuration[10a,10b] consistent with the solid state would lead to the formation of more stable four-coordinate
Eur. J. Inorg. Chem. 2011, 5182–5195
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5185

K.-F. Peng, C.-T. Chen
FULL PAPER
complexes. Complex 5 demonstrates a distorted square-
Suitable crystals for the structural determination of 6
planar geometry, in which the palladium center is coordi- were obtained from a CH2Cl2/n-hexane solution, and the
nated to two nitrogen atoms and one sulfur atom from the molecular structure of 6 is shown in Figure 6. Similar to
pendant anilido-oxazolinate ligand and one oxygen atom palladium β-diketiminate chloride complexes,[1x] 6 demon-
from a η1-acetate group to form a mononuclear species. The strates a chloro-bridged dinuclear species, in which each
Pd–Noxazoline [Pd–N(1) 2.055(4) Å] and Pd–Nanilido bond palladium center is coordinated to two nitrogen atoms from
lengths [Pd–N(2) 1.997(4) Å] and the Noxazoline–Pd–Nanilido the chelating anilido-oxazolinate ligand and two bridging
bite angle [N(1)–Pd–N(2) 89.72(18)°] is similar to those dis- chloride ions. The Pd–Noxazoline [Pd–N(1) 2.0139(18) Å] and
cussed above. The Pd–Sthiomethyl bond [Pd–S 2.2718(15) Å] Pd–Nanilido bond lengths [Pd–N(2) 1.9995(19) Å] and the
is longer than those found in [N,N,S]-type palladium anili-
doiminate complexes [Pd–S 2.2433(7)–2.2503(23) Å].[4g] The are close to those discussed above. The Pd–Cl bond lengths
anilido–Pd–Sthiomethyl bite angle [N(2)–Pd–S 85.27(14)°] is [Pd–Cl 2.3355(7) and 2.3334(7) Å] are close to those found
Noxazoline–Pd–Nanilido bite angle [N(1)–Pd–N(2) 91.11(7)°]
N
smaller than those found in palladium anilidoiminate com- in the corresponding palladium β-diketiminate chloride
plexes [85.61(10)–86.49(6)°].[4g] Similar to 4, the distorted complex [2.342(1) and 2.356(1) Å].[1x] Similar to 1 and 2,
six-membered chelate ring of 5 is characterized by a dihe- the chelate ring of 6 is planar as evidenced by the dihedral
dral angle N(1)–Pd–N(2)/C(1)–C(6)–C(14) of 35.6°.
angle of 2.4° between the planes defined by N(1)–Pd–N(2)/
C(1)–C(6)–C(19).
Figure 5. Molecular structure of 5. Selected bond lengths [Å] and
angles [°]: Pd–N(1) 2.055(4), Pd–N(2) 1.997(4), Pd–O(2) 2.021(4),
Pd–S 2.2718(15), N(1)–Pd–N(2) 89.72(18), O(2)–Pd–S 93.98(14),
N(1)–Pd–O(2) 90.9(2), N(2)–Pd–S 85.27(14), N(1)–Pd–S
174.22(14), N(2)–Pd–O(2) 176.7(2). Hydrogen atoms on carbon
atoms are omitted for clarity.
Figure 6. Molecular structure of 6. Selected bond lengths [Å] and
angles [°]: Pd–N(1) 2.0139(18), Pd–N(2) 1.9995(19), Pd–Cl
2.3355(7), Pd–ClA 2.3334(7), Pd···PdA 3.599, N(1)–Pd–N(2)
91.11(7), Cl–Pd–ClA 79.13(3), N(1)–Pd–ClA 96.35(3), N(2)–Pd–Cl
93.44(6), N(1)–Pd–Cl 174.99(5), N(2)–Pd–ClA 172.52(6), Pd–Cl–
PdA 100.87(3). Hydrogen atoms on carbon atoms are omitted for
clarity.
Synthesis and Characterization of Chloride-Containing
Palladium Complexes 6–8
Suitable crystals for the structural determination of 7
were obtained from a CH2Cl2/n-hexane solution, and the
The reactions of 2, 4, and 5 with an excess of brine in molecular structure of 7 is depicted in Figure 7. The pen-
acetone at room temperature yielded 6, 7, and 8, respec- dant anilido-oxazolinate ligand is a tridentate ligand. Com-
tively, as palladium chloride complexes. The synthesis and plex 7 demonstrates a distorted square-planar geometry, in
proposed structures of these complexes are shown in which the palladium center is coordinated to two nitrogen
Scheme 2. Attempts to synthesize a palladium chloride atoms and one oxygen atom from the pendant anilido-ox-
complex from 1 using a similar route proved unsuccessful. azolinate ligand and one chloride ion to form a mononu-
Purification could not be achieved because of the similar clear species. The Pd–Noxazoline [Pd–N(1) 1.990(4) Å] and
solubility of the major product and byproduct. Compounds Pd–Nanilido bond lengths [Pd–N(2) 1.979(4) Å] and the
6–8 were characterized by single-crystal X-ray diffraction,
Noxazoline–Pd–Nanilido bite angle [N(1)–Pd–N(2) 90.01(16)°]
NMR spectroscopy, and elemental analysis. The disappear- are similar to those discussed above. The Pd–Cl bond
ance of the acetate signal of the palladium acetate precur- length [Pd–Cl 2.3173(3) Å] is close to that found in another
sors in the NMR spectra was consistent with the formation mononuclear palladium chloride complex [2.3158(8) Å].[10f]
of palladium chloride complexes.
The Pd–Omethoxy bond [Pd–O(2) 2.073(3) Å] is shorter than
5186
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 5182–5195

Palladium Complexes Containing Anilido-Oxazolinate Ligands
those found in other palladium complexes bearing a pen- [Pd···PdA 3.0252(2) Å] is similar to that in 3. The distorted
dant methoxy group [Pd–O 2.187(3)–2.4464(17) Å].[10f,11] six-membered chelate ring of 7Ј is characterized by the dihe-
The distorted six-membered chelate ring of 7 is charac- dral angle N(1)–Pd–N(2A)/C(1A)–C(6A)–C(14) of 60.9°.
terized by a dihedral angle N(1)–Pd–N(2)/C(1)–C(6)–C(14)
of 39.4°.
Figure 8. Molecular structure of 7Ј. Selected bond lengths [Å] and
angles [°]: Pd–N(1) 2.0285(16), Pd–N(2) 2.0918(15), Pd–N(2A)
Figure 7. Molecular structure of 7. Selected bond lengths [Å] and
angles [°]: Pd–N(1) 1.990(4), Pd–N(2) 1.979(4), Pd–Cl 2.3173(12),
Pd–O(2) 2.074(3), N(1)–Pd–N(2) 90.01(16), O(2)–Pd–Cl 88.51(10),
N(1)–Pd–Cl 99.16(15), N(2)–Pd–O(2) 82.34(15), N(1)–Pd–O(2)
172.29(15), N(2)–Pd–Cl 170.80(12). Hydrogen atoms on carbon
atoms are omitted for clarity.
2.1007(14), Pd–Cl 2.3326(5), Pd···PdA 3.0252(3), Pd···O(2) 2.928,
N(1)–Pd–N(2A) 85.84(6), N(2)–Pd–N(2A) 87.63(6), N(1)–Pd–Cl
93.98(5), N(2)–Pd–Cl 92.59(4), N(1)–Pd–N(2) 173.43(6), N(2A)–
Pd–Cl 174.08(4), Pd–N(2)–PdA 92.37(6). Hydrogen atoms on car-
bon atoms are omitted for clarity.
1
A small amount of orange crystals were found during
Two sets of signals were observed in the H NMR spec-
the recrystallization of 7 from a CH2Cl2/n-hexane solution tra of 8 with relative intensities of 1.33:1 in C6D6, 1.22:1 in
at room temperature over a few days. Compound 7Ј was C7D8, and 1.86:1 in CDCl3. 13C{1H} NMR spectroscopic
also synthesized by allowing the solution of 7 in CH2Cl2/n- studies confirmed these results. Attempts to separate these
hexane to stand or by stirring the solution of 7 in CHCl3 palladium chloride complexes by recrystallization or
or toluene at room temperature for a few days. An alterna- chromatography proved unsuccessful. Therefore, we pro-
tive route for the preparation of 7Ј by heating a solution of pose that 8 consists of two isomers with different ligand
7 in toluene at 80 °C for 2.5 days results in the formation coordination.[12] It is likely that the dynamic process is asso-
of anilido-bridged palladium complexes as orange solids. ciated with versatile ligand bonding modes[12a,12b] or the
Because of the poor solubility of 7Ј in organic solvents, the fluxionality of the methyl group on the thioether function-
1H NMR spectrum was only recorded in CDCl3. Com- ality.[12c,12d] In order to gain more insight into this process,
1
pound 7Ј was also characterized by single-crystal X-ray dif- high temperature H NMR studies were carried out for 8
fraction and elemental analysis. The molecular structure of in C7D8 from 293 K to 363 K. At 293 K, three kinds of
7Ј is depicted in Figure 8. Similar to 3, 7Ј is a type VII signals could be clearly observed from the following: (1) the
palladium complex, in which each palladium center is coor- signals of the methyl group on the oxazoline group (Ha) are
dinated to three nitrogen atoms (two from the same anilido- located in the range of 1.56–1.60 ppm, (2) two signals of
oxazolinate ligand and one from the second anilido-oxazol- the thiomethyl group (Hb) are located at 2.02 and 2.40 ppm
inate ligand) and one chloride ion. The Pd–Noxazoline [Pd– with a ratio of relative intensities of 1.22:1, and (3) the sig-
N(1) 2.0285(16) Å], Pd–Cl [Pd–Cl 2.3326(5) Å], and Pd– nals of the methylene groups on the oxazoline group (Hc)
Nanilido bond lengths [Pd–N(2) 2.0918(15) and Pd–N(2A) are located at 3.35 and 3.66 ppm (overlap of two doublets).
2.1007(14) Å] are similar to those discussed above. The These peaks coalesced to broad signals upon heating from
N
oxazoline–Pd–Nanilido bite angle [N(1)–Pd–N(2A) 85.84(6)°] 323 to 343 K and merge to three broad peaks upon heating
is smaller than those discussed above, which might result from 353 K to 363 K, as shown in Figure 9. These observa-
from the twist of the ligand backbone to fit the square- tions indicate that a dynamic process could occur in solu-
planar geometry. The distance between two Pd centers tion with different ligand coordination or fluxionality of the
Eur. J. Inorg. Chem. 2011, 5182–5195
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5187

K.-F. Peng, C.-T. Chen
FULL PAPER
1
Figure 9. Variable temperature H NMR spectra for 8 ([D8]toluene, 600 MHz).
methyl group on the thioether functionality to form another Catalytic Studies
chemical environment could occur, which supports the ob-
servation that such a ligand could coordinate to palladium
Palladium-catalyzed cross-coupling reactions are power-
by versatile bonding modes or different orientations and ful and convenient tools for carbon–carbon bond formation
two conformers are found at room temperature. One of in modern organic synthesis.[13] Based on the catalytic cy-
these two isomers was identified by single-crystal X-ray cles mentioned by most reports,[13] ancillary ligands with
structure determination. Suitable crystals of 8 were ob- bulky, electron-rich properties, such as phosphanes[14] and
tained from a CH2Cl2/n-hexane solution, and the molecular N-heterocyclic carbenes,[15] play an important role in en-
structure of 8 is depicted in Figure 10. Complex 8 is similar hancing catalytic activity. However, sensitivity, toxicity, and
to 5 but with a coordinated chloride ion instead of an acet- economic considerations result in significant limitations on
ate group. The bond lengths [Pd–Noxazoline 2.0490(18) Å; their synthetic application. Therefore, many metal com-
Pd–Nanilido 2.0152(17) Å; Pd–S 2.2479(5) Å] and bite angle plexes bearing nitrogen- or oxygen-based ligands,[16] such as
[Noxazoline–Pd–Nanilido 89.01(7)°] are similar to those dis- guanidines,[16a] amidines,[16b,16c] diamines,[16d,16e] di-
cussed above for 5. The Pd–Cl bond length [Pd–Cl imines,[16f–16i] simple amines,[16j,16k] Schiff bases (half
2.3234(6) Å] is close to that discussed above for 7. Similar SALEN),[16l–16r] and diketones,[16s] and heterocyclic li-
to 5, The distorted six-membered chelate ring of 8 is charac- gands,[17] such as oxazolines,[5c,5d,17c–17h] pyridines,[17i–17l]
terized by the dihedral angle N(1)–Pd–N(2)/C(1)–C(6)– quinolines,[17m] pyrazoles,[17n–17r] imidazoles,[17s–17u] 1,4-di-
C(14) of 41.3°.
azabicyclooctane,[17v–17x] and piperazines,[17y,17z] have been
5188
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 5182–5195

Palladium Complexes Containing Anilido-Oxazolinate Ligands
14). Reexamination of the biphasic system with EtOH/H2O
using an optimized volume ratio of 1:3 led to a better con-
version of 97% within 10 min (Entry 15). The optimized
base was found to be K3PO4 after trials with several bases
such as K3PO4, KF, and Cs2CO3 (Entries 15–17). After ex-
amining the catalytic activities of 1–8 using the optimized
conditions, 2 was found to exhibit the best conversion
within 10 min (Entries 15, 18–25 in Table 1 and Figure S1).
This might result from the bulkier substituents on the anil-
ido group. The results also showed that acetate-containing
1, 2, and 4 were more active than chloride-containing 6.
Poor conversions were found with [N,N,S]-type 5 and 8, in-
dicating that a better interaction between the palladium
center and the pendent sulfur atom might result in poor
activities. However, the [N,N,O]-type 7 was more active than
[N,N,S]-type 5 and 8. Due to their poor solubility in the
cosolvent system, poor activities were observed using type
VII 3 and 7Ј as catalyst precursors. Complex 2 also demon-
strated good conversions within 10–30 min for electroni-
cally deactivated substrates, even ortho-substituted aryl bro-
mides (Entries 26–29). However, poor conversion was ob-
served within 24 h using 2-bromomesitylene as the substrate
Figure 10. Molecular structure of 8. Selected bond lengths [Å] and
angles [°]: Pd–N(1) 2.0490(18), Pd–N(2) 2.0152(17), Pd–Cl under the optimized conditions at 50 °C (Entry 30), which
2.3234(6), Pd–S 2.2479(5), N(1)–Pd–N(2) 89.01(7), S–Pd–Cl
might result from the steric effect of the substrate. A lower
85.97(2), N(1)–Pd–Cl 98.37(5), N(2)–Pd–S 86.71(5), N(1)–Pd–S
catalyst concentration (catalyst/substrate ratio of 10–4:1) led
175.03(5), N(2)–Pd–Cl 172.53(5). Hydrogen atoms on carbon
to a conversion of 91% within 2 h at 50 °C (Entry 31),
atoms are omitted for clarity.
whereas a catalyst/substrate ratio of 10–5:1 gave a poor con-
version (30%) within 24 h at 80 °C (Entry 32). The turnover
numbers (TONs) achieved were up to 9.1ϫ103 and
examined for their catalytic activities in cross-coupling reac-
tions. Due to the success of some palladium complexes con-
3.0ϫ104 using deactivated 4-bromoanisole as the substrate.
Poor conversion (11%) was observed within 24 h at 80 °C
using 4-chloroacetophenone as the substrate on a 1 mol-
% scale with 2 (Entry 33). Comparing with some reports
concerned with catalytic systems containing oxazoline
groups or alcohol/H2O for the Suzuki reaction, under opti-
mized conditions 2 exhibited better activity than palladium
complexes containing anilido-oxazoline[5d] and oxazoline li-
taining anilido or oxazoline groups in cross-coupling reac-
tions, 1–8 are expected to work as catalysts in Suzuki and
Heck reactions.
Suzuki Reaction
We examined the catalytic activities of 1–8 in the Suzuki gands[17d–17f] and some catalytic systems using EtOH/H2O
reaction using the coupling of aryl halides with phen- as cosolvent, such as Pd(OAc)2/guanidine[16a] and a (quin-
ylbronic acid on a 1 mol-% Pd scale, as shown in Scheme 4. oline-8-carboxylato)palladium complex.[17m]
Selected results are listed in Table 1. The solvent system was
optimized by introducing nonpolar or polar solvents, such
as toluene, THF, dichloromethane, acetonitrile, N,N-di-
methylformamide (DMF), N,N-dimethylacetamide (DMA),
methanol or H2O, in the coupling of 4-bromoanisole with
phenylboronic acid in the presence of K3PO4 at room tem-
Scheme 4. Application of 1–8 to the Suzuki reaction.
perature on a 1 mol-% scale with 2. However, poor conver-
sions (Ͻ 30%) were observed within 30 min (Entries 1–8).
The catalytic activity was improved by using a biphasic sys-
Heck Reaction
tem in the presence of TBAB (tetra-n-butylammonium bro-
mide).[18] Complex 2 was used to examine the catalytic ac-
We also examined the catalytic activities of 1–8 in the
tivities on a 1 mol-% scale using 4-bromoanisole as the sub- Heck reaction using the coupling of aryl halides with sty-
strate with the volume ratio of solvent/H2O of rene on a 1 mol-% Pd scale, as shown in Scheme 5. Selected
1:1.[17m,18j,18k] The optimized solvent system for these con- results are listed in Table 2. When 4-bromoacetophenone
ditions was found to be EtOH/H2O after examining the bi- was used as the substrate, the optimized base/solvent mix-
phasic systems, such as CH3CN/H2O,[18e,18f] DMF/ ture for the reaction using 2 was found to be K3PO4/DMA
H2O,[16h,16,16m,16o,17j,17o,18g–18i] ROH/H2O[16a,17k,17m,18i–18m] after trials with a combination of bases (K3PO4, KF, and
(ROH = MeOH, EtOH, iPrOH, and tBuOH; Entries 9– Cs2CO3) and solvents (THF, toluene, and DMA; Entries 1–
Eur. J. Inorg. Chem. 2011, 5182–5195
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5189

K.-F. Peng, C.-T. Chen
FULL PAPER
Table 1. Suzuki–Miyaura reaction catalyzed by 1–8.[a]
Entry
Catalyst Aryl halide
4-bromoanisole
Base
Solvent
Pd [mol-%] T [°C]
t [min]
Conv. [%][b]
Yield [%][c]
1
2
3
4
5
6
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
3
4
5
6
7
7Ј
8
2
2
2
2
2
2
2
2
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
KF
Cs2CO3
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
toluene
THF
CH2Cl2
CH3CN
DMF
DMA
MeOH
H2O
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
room temp.
30
30
30
30
30
30
30
30
30
30
30
30
30
30
10
10
10
10
10
10
10
10
10
10
10
10
30
30
30
24 hr
2 hr
24 hr
24 hr
15
7
13
9
–
–
–
–
–
–
–
–
–
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromotoluene
4-tBu-bromobenzene
2-bromoanisole
2-bromotoluene
2-bromomesitylene
4-bromoanisole
4-bromoanisole
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
room temp.
50
Ͻ5
Ͻ5
28
12
18
27
87
99
65
67
97
22
70
90
9
84
6
78
77
10
5
95
90
92
93
13
91
30
11
7
8[d]
9[d,e]
10[d,e]
11[d,e]
12[d,e]
13[d,e]
14[d,e]
15[d,f]
16[d,f]
17[d,f]
18[d,f]
19[d,f]
20[d,f]
21[d,f]
22[d,f]
23[d,f]
24[d,f]
25[d,f]
26[d,f]
27[d,f]
28[d,f]
29[d,f]
30[d,f]
31[d,f]
32[d,f]
33[d,f]
CH3CN/H2O
DMF/H2O
MeOH/H2O
EtOH/H2O
iPrOH/H2O
tBuOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
EtOH/H2O
–
83
97
–
–
92
–
–
83
–
80
–
–
–
–
–
90
85
87
90
–
88
–
–
1
0.01
0.001
1
50
80
80
4-chloroacetophenone K3PO4
1
[a] Reaction conditions: aryl halide (1.0 mmol), phenylboronic acid (1.5 mmol), base (2.0 mmol), solvent (2 mL). [b] Determined by H
NMR spectroscopy. [c] Isolated yield (average of two runs). [d] Addition of 50 mol-% TBAB. [e] Volume ratio: 1:1. [f] Volume ratio: 1:3.
3). Poor conversion was observed when 4-bromoanisole was ever, it took 48 h to achieve 68% conversion with a 10–4:1
used as the substrate under the optimized base/solvent con- ratio (Entries 17 and 19). The TONs achieved were up to
ditions (Entry 4). However, the conversion was enhanced 9.3ϫ102 and 6.8ϫ103. For the deactivated 4-bromoanisole,
up to 73% for 4-bromoanisole using similar conditions with moderate conversion (60%) was achieved within 48 h with
the addition of 20 mol-% TBAB (Entry 5). The optimized a 10–3:1 ratio, whereas a poor conversion (Ͻ 5%) was ob-
conditions were used to examine the catalytic activities of tained within 48 h with a 10–4:1 ratio (Entries 18 and 20).
1–8. The highest reactivity was observed for 6 with a con- The TON achieved was up to 6.0ϫ102 using deactivated 4-
version of up to 76% (Entries 5–13 in Table 2 and Figure bromoacetophenone as the substrate (Entry 18). Complex 6
S2). Compared with the trend of the Suzuki reaction, chlo- also exhibited activity for catalyzing chlorinated substrates
ride-containing 6 and 7 were more active than acetate-con- under the optimized conditions. A conversion of up to 94%
taining 2 and 4. Poor activities were also observed using within 4 h was achieved using activated 4-chloroacetophen-
type VII 3 and 7Ј due to their poor solubilities. Even under one as a substrate (Entry 21); however, a poor conversion
high temperature conditions, [N,N,S]-type 5 and 8 exhibited (5%) was observed using 4-chloroanisole as the substrate
poor conversions probably due to the strong coordination (Entry 22). Under the optimized conditions, 6 exhibited
between the palladium center and the pendent sulfur atom. better catalytic activities than some palladium complexes
Better conversions were achieved of up to 90% within 2.5 to containing anilido-oxazoline[5c,5d] and oxazoline li-
7 h for 4-bromoanisole, 4-bromotoluene, and 4-tert-butyl- gands.[17d–17f]
bromobenzene using 6 under the optimized conditions (En-
tries 14–16). Lower catalyst concentrations of 6 were inves-
tigated on catalyst/substrate ratios from 10–3 to 10–4:1 using
4-bromoacetophenone and 4-bromoanisole as the sub-
strates. For the activated 4-bromoacetophenone, 93% con-
version was achieved within 6 h with a 10–3:1 ratio, how- Scheme 5. Application of 1–8 to the Heck reaction.
5190
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 5182–5195

Palladium Complexes Containing Anilido-Oxazolinate Ligands
Table 2. Heck reaction catalyzed by 1–8.[a]
Entry
Catalyst
Aryl halide
Base
Solvent
Pd [mol-%]
T [°C]
t [h]
Conv. [%][b]
Yield [%][c]
1
2
3
2
2
2
2
2
1
3
4
5
6
7
7Ј
8
6
6
6
6
6
6
6
6
6
4-bromoacetophenone
4-bromoacetophenone
4-bromoacetophenone
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
KF
THF
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
70
1
1
1
1
1
1
1
1
1
1
1
1
1
2.5
3.5
7
5
58
97
10
73
54
45
50
5
76
62
34
10
90
90
93
93
60
68
Ͻ5
94
5
–
–
91
–
–
–
–
–
–
–
–
–
–
85
84
87
86
–
Cs2CO3
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
K3PO4
toluene
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
110
135
135
135
135
135
135
135
135
135
135
135
135
135
135
135
135
135
135
135
135
4
5[d]
6[d]
7[d]
8[d]
9[d]
10[d]
11[d]
12[d]
13[d]
14[d]
15[d]
16[d]
17[d]
18[d]
19[d]
20[d]
21[d]
22[d]
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromoanisole
4-bromotoluene
4-tert-butylbromobenzene
4-bromoacetophenone
4-bromoanisole
4-bromoacetophenone
4-bromoanisole
0.1
0.1
0.01
0.01
1
6
24
48
48
4
–
–
85
–
4-chlorooacetophenone
4-chloroanisole
1
24
1
[a] Reaction conditions: aryl halide (1.0 mmol), styrene (1.3 mmol), base (1.5 mmol), solvent (2 mL). [b] Determined by H NMR spec-
troscopy. [c] Isolated yield (average of two runs). [d] Addition of 20 mol-% TBAB.
inate complexes bearing bulkier substituents on the anilido
group were found to be efficient catalyts in both Suzuki and
Conclusions
A series of palladium anilido-oxazolinate complexes with
or without pendant functionalities was synthesized and
characterized. Based on the molecular structures, versatile
bonding modes were found with different substituents on
the anilido group. Due to the steric hindrance of the substit-
Heck reactions.
Experimental Section
uents on the anilido groups, 1 and 2 were observed as mo- General Procedures and Instruments: All manipulations were car-
nonuclear complexes with a η2-acetate group. The type VII
ried out under an atmosphere of dinitrogen using standard Schlenk
or drybox techniques. Toluene, THF, dichloromethane, and n-hex-
ane were heated to reflux with the appropriate drying agent and
distilled prior to use. Methanol, ethanol, 2-propanol, tert-butyl
bonding mode of dinuclear 3 with a η1-acetate group is
rare. Complex 4 was found to be a dinuclear complex with
two bridging acetate ligands bearing the less bulky anilido
alcohol, acetonitrile, chloroform, DMF, and DMA were used as
group. For 5, the palladium center was found to be sur-
1
received. Deuterated solvents were dried with molecular sieves. H
rounded by a tridentate ligand with a η1-acetate group to
and 13C{1H} NMR spectra were recorded with Varian Mercury-
complete the square-planar geometry. The palladium anil-
ido-oxazolinate chloride complex 6, which contains bulkier
anilido groups, exhibited a dinuclear structure with two
400 (400 MHz) or Varian Inova-600 (600 MHz) spectrometers in
CDCl3 or C6D6 at ambient temperature and referenced internally
to the residual solvent peak and reported as parts per million rela-
bridging chloride ions. However, the preparation of a palla- tive to tetramethylsilane. Elemental analyses were performed with
an Elementar Vario EL III instrument. HRMS (EI) were recorded
with a Finnigan/Thermo Quest MAT 95XL spectrometer. Pd-
(OAc)2 (Acros), K3PO4 (Lancaster), KF (Lancaster), Cs2CO3
(Lancaster), and TBAB (TCI) were used as supplied. Ligand pre-
cursors, HNPhTriMeOxa, HNPhDiiPrOxa, HNPhOMeOxa, and
HNPhSMeOxa, were prepared as described previously.[5g,5h]
dium chloride complex from 4 resulted in a mixture of mo-
nonuclear 7 with coordination of the pendant methoxy
functionality as the major product and dinuclear anilido-
bridged palladium chloride complex 7Ј as the minor prod-
uct, in which the ligands coordinate to the metal centers in
a similar bonding mode to 3. Based on variable-tempera-
(NPhTriMeOxa)Pd(η2-OAc) (1): To a flask containing Pd(OAc)2
(0.32 g, 1.43 mmol) and HNPhTriMeOxa (0.40 g, 1.3 mmol) was
added THF (30 mL) at room temperature. The reaction mixture
was heated to reflux for 14 h. After cooling to room temperature,
the reaction mixture was filtered, and the filtrate was evaporated
to dryness. The crude product was washed with n-hexane (10 mL)
to afford a green solid; yield 0.55 g (90%). 1H NMR (CDCl3,
600 MHz): δ = 1.46 [s, 6 H, oxazoline-C(CH3)2], 1.74 [s, 3 H, O–
C(=O) –CH3], 2.24 [s, 3 H, p-(CH3)Ph], 2.28 [s, 6 H, o-(CH3)2Ph],
1
ture H NMR spectroscopy, we proposed that 8 consists of
two conformers in solution at room temperature. The cata-
lytic activities of 1–8 towards the Suzuki and Heck reac-
tions were examined. Under optimized conditions, 2 exhib-
ited higher activity in the Suzuki reaction within 10 min at
room temperature with 4-bromoanisole in a biphasic system
of EtOH/H2O. Complex 6 demonstrated better reactivity
for 4-bromoanisole under optimized conditions in the Heck
reaction. Based on these results, palladium anilido-oxazol- 4.29 (s, 2 H, oxazoline-CH2), 5.97 (d, J = 9.0 Hz, 1 H, Ph-H), 6.29
Eur. J. Inorg. Chem. 2011, 5182–5195
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5191

K.-F. Peng, C.-T. Chen
FULL PAPER
(t, J = 7.2 Hz, 1 H, Ph-H), 6.83 (m, 1 H, Ph-H), 6.90 (s, 2 H, Ph- washed with n-hexane (10 mL) to afford a purple solid; yield 0.47 g
1
H), 7.57 (m, 1 H, Ph-H) ppm. 13C{1H} NMR (CDCl3, 150 MHz):
(99%). H NMR (CDCl3, 600 MHz): δ = 1.49 [s, 3 H, oxazoline-
δ = 18.6 [s, o-(CH3)2Ph], 21.3 [s, p-(CH3)Ph], 23.8 [s, O–C(=O)– C(CH3)2], 1.68 [s, 3 H, oxazoline-C(CH3)2], 1.99 [s, 3 H, O–C(=O)–
CH3], 28.1 [s, oxazoline-C(CH3)2], 67.7 [s, oxazoline-C(CH3)2], 80.0
(s, oxazoline-CH2), 112.3, 115.3, 129.1, 129.5, 132.8 (s, CH-Ph),
103.6, 134.9, 136.5, 141.8, 151.0, 159.9 (Cquat), 191.5 [s, O-C(=O)-
CH3] ppm. C22H26N2O3Pd (472.86): calcd. C 55.88, H 5.54, N 5.92;
found C 56.42: H 5.80: N 6.29.
CH3], 2.87 (s, 3 H, SCH3), 4.15 (d, J = 8.4 Hz, 1 H, oxazoline-
CH2), 4.39 (d, J = 7.8 Hz, 1 H, oxazoline-CH2), 6.61 (t, J = 7.2 Hz,
1 H, Ph-H), 6.65 (t, J = 7.8 Hz, 1 H, Ph-H), 7.03 (t, J = 8.4 Hz, 1
H, Ph-H), 7.09 (t, J = 8.4 Hz, 1 H, Ph-H), 7.25 (d, J = 8.4 Hz, 1
H, Ph-H), 7.33 (d, J = 7.2 Hz, 1 H, Ph-H), 7.44 (d, J = 7.8 Hz, 1
H, Ph-H), 7.60 (d, J = 8.4 Hz, 1 H, Ph-H) ppm. 13C{1H} NMR
(CDCl3, 150 MHz): δ = 23.2 [s, O-C(=O)-CH3], 26.5 [s, oxazoline-
C(CH3)2], 27.9 [s, oxazoline-C(CH3)2], 30.7 (s, SCH3), 68.8 [s, oxaz-
oline-C(CH3)2], 81.4 (s, oxazoline-CH2), 117.1, 119.1, 119.4, 120.6,
130.1, 130.2, 131.7, 132.5 (s, CH-Ph), 115.2, 124.7, 151.6, 158.9,
162.4 (Cquat), 177.6 [s, O–C(=O)–CH3] ppm. C20H22N2O3PdS
(476.87): calcd. C 50.37, H 4.65, N 5.87; found C 49.72, H 4.74, N
5.84.
(NPhDiiPrOxa)Pd(η2-OAc) (2): To a flask containing Pd(OAc)2
(0.25 g, 1.1 mmol) and HNPhDiiPrOxa (0.35 g, 1.0 mmol) was
added THF (30 mL) at room temperature. The reaction mixture
was heated to reflux for 4 h. After cooling to room temperature,
the reaction mixture was filtered, and the filtrate was evaporated
to dryness. The crude product was washed with n-hexane (10 mL)
to afford a green solid; yield 0.44 g (85%). 1H NMR (CDCl3,
600 MHz): δ = 1.04 [d, J = 7.2 Hz, 6 H, (CH3)2CH], 1.46 [d, J =
6.6 Hz, 6 H, (CH3)2CH], 1.47 [s, 6 H, oxazoline-C(CH3)2], 1.70 [s,
3 H, O–C(=O)–CH3], 3.54 [sept, 2 H, (CH3)2CH], 4.30 (s, 2 H,
oxazoline-CH2), 5.98 (d, J = 8.4 Hz, 1 H, Ph-H), 6.29 (m, 1 H, Ph-
H), 6.81 (m, 1 H, Ph-H), 7.15 (d, J = 7.8 Hz, 2 H, Ph-H), 7.30 (t,
J = 7.8 Hz, 1 H, Ph-H), 7.58 (dd, J = 8.4 & 1.2 Hz, 1 H, Ph-H)
ppm. 13C{1H} NMR (CDCl3, 150 MHz): δ = 23.5 [s, O–C(=O)–
CH3], 24.03, 24.14 [s, (CH3)2CH], 28.1 [signal overlap, (CH3)2CH
and oxazoline-C(CH3)2], 67.8 [s, oxazoline-C(CH3)2], 80.1 (s, oxaz-
oline-CH2), 112.3, 116.8, 123.7, 126.5, 129.4, 132.3 (s, CH-Ph),
103.1, 141.5, 147.1, 151.9, 160.0 (Cquat), 191.0 [s, O–C(=O)–CH3]
ppm. C25H32N2O3Pd (514.94): calcd. C 58.31, H 6.26, N 5.44;
found C 58.93, H 6.62, N 5.57.
[(NPhDiiPrOxa)Pd(μ-Cl)]2 (6): To a flask containing 2 (0.26 g,
0.5 mmol) were added acetone (15 mL) and brine (15 mL) at room
temperature. After stirring for 14 h, the green suspension was fil-
tered, and the precipitate was washed with deionized water (10 mL)
followed by n-hexane (10 mL) to afford a green solid; yield 0.24 g
1
(98%). H NMR (CDCl3, 600 MHz): δ = 0.95 [d, J = 7.2 Hz, 12
H, (CH3)2CH], 1.13 [s, 12 H, oxazoline-C(CH3)2], 1.51 [d, J =
7.2 Hz, 12 H, (CH3)2CH], 3.42 [sept, 4 H, (CH3)2CH], 4.06 (s, 4 H,
oxazoline-CH2), 5.92 (d, J = 9.0 Hz, 2 H, Ph-H), 6.25 (m, 2 H, Ph-
H), 6.75 (m, 2 H, Ph-H), 7.04 (d, J = 7.8 Hz, 2 H, Ph-H), 7.13 (t,
J = 7.8 Hz, 2 H, Ph-H), 7.59 (dd, J = 8.4 and 1.2 Hz, 2 H, Ph-H)
ppm. 13C{1H} NMR (CDCl3, 150 MHz): δ = 24.1, 24.5 [s,
(CH3)2CH], 27.4 [s, oxazoline-C(CH3)2], 27.9 [s, (CH3)2CH], 70.1
[s, oxazoline-C(CH3)2], 80.8 (s, oxazoline-CH2), 112.4, 117.3, 123.7,
125.7, 130.0, 132.1 (s, CH-Ph), 102.8, 146.0, 146.3, 151.7, 161.0
(Cquat) ppm. C46H58Cl2N4O2Pd2 (982.70): calcd. C 56.22, H 5.95,
N 5.70; found C 55.87, H 6.19, N 5.91.
(NPhOMeOxa)Pd(Cl) (7): To a flask containing 4 (0.46 g, 0.5 mmol)
were added acetone (15 mL) and brine (15 mL) at room tempera-
ture. After stirring for 1.5 h, the green suspension was filtered, and
the residue was washed with deionized water (10 mL) followed by
n-hexane (10 mL) to afford a green solid; yield 0.40 g (91%). 1H
NMR (CDCl3, 600 MHz): δ = 1.69 [s, 6 H, oxazoline-C(CH3)2],
4.15 (s, 3 H, OCH3), 4.30 (br., 2 H, oxazoline-CH2), 6.61 (t, J =
7.2 Hz, 1 H, Ph-H), 6.74 (m, 1 H, Ph-H), 6.86 (m, 1 H, Ph-H), 7.02
(d, J = 8.4 Hz, 1 H, Ph-H), 7.13 (m, 1 H, Ph-H), 7.42 (m, 1 H, Ph-
H), 7.54 (d, J = 8.4 Hz, 1 H, Ph-H), 7.59 (dd, J = 7.8 & 1.2 Hz, 1
H, Ph-H) ppm. 13C{1H} NMR (CDCl3, 150 MHz): δ = 27.4 [s,
oxazoline-C(CH3)2], 61.8 (s, OCH3), 69.7 [s, oxazoline-C(CH3)2],
81.4 (s, oxazoline-CH2), 113.7, 116.0, 116.3, 120.0, 120.3, 123.4,
[(μ-NPhHOxa)Pd(OAc)]2 (3): To a flask containing Pd(OAc)2
(0.25 g, 1.1 mmol) and HNPhHOxa (0.27 g, 1.0 mmol) was added
toluene (10 mL) at room temperature. The mixture was stirred at
50 °C for 6 h. After cooling to room temperature, the reaction mix-
ture was filtered, and the residue was evaporated to dryness. The
crude product was washed with n-hexane (10 mL) to afford an
orange solid; yield 0.33 g (77%). C38H40N4O6Pd2 (861.56): calcd.
C 52.97, H 4.68, N 6.50; found C 52.78, H 4.59, N 6.24. HRMS:
calcd. for C38H40N4O6Pd2 [M + H]+ 861.1018; found 861.1082.
[(NPhOMeOxa)Pd(μ-OAc)]2 (4): To a flask containing Pd(OAc)2
(0.25 g, 1.1 mmol) and HNPhOMeOxa (0.30 g, 1.0 mmol) was
added CHCl3 (10 mL) at room temperature. The reaction mixture
was stirred at 60 °C for 3 h. After cooling to room temperature, the
reaction mixture was filtered, and the filtrate was evaporated off to
dryness. The crude product was washed with n-hexane (10 mL) to
afford a brown solid; yield 0.41 g (88%). 1H NMR (C6D6,
600 MHz): δ = 1.11 [s, 6 H, oxazoline-C(CH3)2], 1.16 [s, 6 H, oxaz-
oline-C(CH3)2], 1.26 [s, 6 H, O–C(=O)–CH3], 3.36 (s, 6 H, OCH3),
3.43 (s, 4 H, oxazoline-CH2), 6.39 (m, 2 H, Ph-H), 6.59 (d, J =
9.0 Hz, 2 H, Ph-H), 6.63 (d, J = 7.2 Hz, 2 H, Ph-H), 6.82 (m, 2 H,
Ph-H), 6.93 (m, 2 H, Ph-H), 7.11 (m, 2 H, Ph-H), 7.48 (d, J =
7.2 Hz, 2 H, Ph-H), 7.86 (d, J = 8.4 Hz, 2 H, Ph-H) ppm. 13C{1H}
NMR (C6D6, 150 MHz): δ = 23.1 [s, O–C(=O)–CH3], 27.4, [s, oxaz-
oline-C(CH3)2], 27.8 [s, oxazoline-C(CH3)2], 55.2 (s, OCH3), 67.7
[s, oxazoline-C(CH3)2], 79.6 (s, oxazoline-CH2), 111.9, 113.0, 117.4,
121.6, 127.0, 129.8, 131.9, 132.9 (s, CH-Ph), 104.7, 136.7, 153.0,
157.0, 160.5 (Cquat), 191.4 [s, O–C(=O)–CH3] ppm.
C40H44N4O8Pd2 (921.61): calcd. C 52.13, H 4.81, N 6.08; found C
52.15, H 4.82, N 5.94.
130.1, 132.9 (s, CH-Ph), 112.9, 140.2, 149.6, 154.7, 161.5 (Cquat
)
ppm. C18H19ClN2O2Pd (437.21): calcd. C 49.45, H 4.38, N 6.41;
found C 49.88, H 4.82, N 6.74.
[(μ-NPhOMeOxa)Pd(Cl)]2 (7Ј): To a flask containing 7 (0.26 g,
0.60 mmol) was added toluene (3.0 mL) at room temperature. The
reaction mixture was stirred at 80 °C for 2.5 d. After cooling to
room temperature, the brown suspension was filtered, and the resi-
due was washed with toluene (10 mL) to afford an orange solid;
1
yield 0.20 g (77%). H NMR (CDCl3, 600 MHz): δ = 0.90 [s, 6 H,
oxazoline-C(CH3)2], 1.36 [s, 6 H, oxazoline-C(CH3)2], 3.61 [s, 6 H,
o-(OCH3)Ph], 3.65 (d, J = 8.4 Hz, 2 H, oxazoline-CH2), 4.00 (d, J
= 8.4 Hz, 2 H, oxazoline-CH2), 5.66 (d, J = 8.0 Hz, 2 H, Ph-H),
(NPhSMeOxa)Pd(OAc) (5): To a flask containing Pd(OAc)2 (0.25 g, 6.33 (t, J = 7.2 Hz, 2 H, Ph-H), 6.88 (t, J = 7.6 Hz, 2 H, Ph-H),
1.1 mmol) and HNPhSMeOxa (0.32 g, 1.0 mmol) was added CH2Cl2
(30 mL) at room temperature. The reaction mixture was stirred at 7.61 (d, J = 6.8 Hz, 2 H, Ph-H), 7.91 (t, J = 8.0 Hz, 2 H, Ph-H),
6.95 (d, J = 8.0 Hz, 2 H, Ph-H), 7.48 (t, J = 7.6 Hz, 2 H, Ph-H),
room temperature for 1 h. The reaction mixture was filtered, and
the filtrate was evaporated to dryness. The crude product was
9.67 (d, J = 8.4 Hz, 2 H, Ph-H) ppm. C36H38Cl2N4O4Pd2 (874.43):
calcd. C 49.45, H 4.38, N 6.41; found C 49.07, H 4.75, N 6.43.
5192
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 5182–5195

Palladium Complexes Containing Anilido-Oxazolinate Ligands
(NPhSMeOxa)Pd(Cl) (8): To
flask containing (0.17 g,
a
5
the SADABS program.[19] For 6 and 7, empirical absorption correc-
tion was based on spherical harmonics implemented in SCALE3
ABSPACK scaling algorithm from CrysAlis RED, Oxford Diffrac-
tion Ltd. The space group determination was based on the Laue
symmetry and systematic absences and was confirmed using the
structure solution. The structures were solved by direct methods
using a SHELXTL package.[20] All non-H atoms were located from
successive Fourier maps, and hydrogen atoms were refined using a
riding model. Anisotropic thermal parameters were used for all
non-H atoms, and fixed isotropic parameters were used for H
atoms. Some details of the data collection and refinement are given
in Tables S1 and S2.
0.36 mmol) were added acetone (10 mL) and brine (10 mL) at room
temperature. After stirring for 0.5 h, the purple suspension was
filtered, and the precipitate was washed with deionized water
(10 mL) and n-hexane (10 mL) to afford a purple solid; yield 0.12 g
(71%). A ratio of 1.33:1 was displayed for the two isomers in C6D6.
1
For the major isomer: H NMR (C6D6, 600 MHz): δ = 1.58 [s, 3
H, oxazoline-C(CH3)2], 1.61 [s, 3 H, oxazoline-C(CH3)2], 2.00 [s, 3
H, o-(SCH3)Ph], 3.29 (d, J = 7.8 Hz, 1 H, oxazoline-CH2), 3.58 (d,
J = 8.4 Hz, 1 H, oxazoline-CH2), 6.32 (t, J = 7.2 Hz, 1 H, Ph-H),
6.54 (signal overlap, 1 H, Ph-H), 6.70 (t, J = 7.5 Hz, 1 H, Ph-H),
6.76 (d, J = 7.2 Hz, 1 H, Ph-H), 6.89 (m, 1 H, Ph-H), 7.25 (d, J =
8.4 Hz, 1 H, Ph-H), 7.40 (d, J = 9.0 Hz, 3 H, Ph-H), 7.70 (t, J =
6.3 Hz, 1 H, Ph-H) ppm. 13C{1H} NMR (C6D6, 150 MHz): δ =
27.8 [s, o-(SCH3)Ph], 27.37 [s, oxazoline-C(CH3)2], 28.2 [s, oxazol-
ine-C(CH3)2], 70.1 (Cquat), 81.4 (s, oxazoline-CH2), 117.4, 118.6,
120.2, 121.5, 128.8, 130.5, 132.8 (s, CH-Ph), 115.9, 123.5, 152.3,
CCDC-762654 (for 1), -762655 (for 2), -833347 (for 3), -762656
(for 4), -762657 (for 5), -762658 (for 6), -762659 (for 7), -762660
(for 7Ј), and -762661 (for 8) contain the supplementary crystallo-
graphic 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.
1
159.8, 162.7 (Cquat) ppm. For the minor isomer: H NMR (C6D6,
600 MHz): δ = 1.60 [s, 3 H, oxazoline-C(CH3)2], 1.63 [s, 3 H, oxaz-
oline-C(CH3)2], 2.36 [s, 3 H, o-(SCH3)Ph], 3.31 (d, J = 7.8 Hz, 1
H, oxazoline-CH2), 3.60 (d, J = 8.4 Hz, 1 H, oxazoline-CH2), 6.38
(t, J = 7.2 Hz, 1 H, Ph-H), 6.54 (signal overlap, 2 H, Ph-H), 6.66
(t, J = 7.5 Hz, 1 H, Ph-H), 6.83 (m, 1 H, Ph-H), 7.21 (d, J = 8.4 Hz,
1 H, Ph-H), 7.37 (d, J = 9.0 Hz, 1 H, Ph-H), 7.70 (t, J = 6.3 Hz, 1
H, Ph-H) ppm. 13C{1H} NMR (C6D6, 150 MHz): δ = 24.7 [s, o-
(SCH3)Ph], 27.41 [s, oxazoline-C(CH3)2], 28.4 [s, oxazoline-C-
(CH3)2], 70.2 (Cquat), 81.5 (s, oxazoline-CH2), 117.5, 119.1, 120.5,
121.4, 129.6, 130.7, 132.5 (s, CH-Ph), 116.5, 125.9, 152.5, 158.1,
162.5 (Cquat) ppm. C18H19ClN2OPdS (453.27): calcd. C 47.69, H
4.22, N 6.18; found C 47.99, H 4.33, N 6.02.
Acknowledgments
We would like to thank the National Science Council of the Repub-
lic of China for financial support (NSC 98-2113-M-005-002-MY3).
[1] a) L. Bourget-Merle, M. F. Lappert, J. R. Severn, Chem. Rev.
2002, 102, 3031–3065; b) S. Nagendran, H. W. Roesky, Organo-
metallics 2008, 27, 457–492; c) P. H. M. Budzelaar, N. N. P.
Moonen, R. de Gelder, J. M. M. Smits, A. W. Gal, Eur. J. Inorg.
Chem. 2000, 753–769; d) J. Spielmann, S. Harder, Eur. J. Inorg.
Chem. 2008, 1480–1486; e) M. R. Crimmin, M. Arrowsmith,
A. G. M. Barrett, I. J. Casely, M. S. Hill, P. A. Procopiou, J.
Am. Chem. Soc. 2009, 131, 9670–9685; f) K. C. MacLeod, B. O.
Patrick, K. M. Smith, Organometallics 2010, 29, 6639–6641; g)
M. Cheng, D. R. Moore, J. J. Reczek, B. M. Chamberlain, E. B.
Lobkovsky, G. W. Coates, J. Am. Chem. Soc. 2001, 123, 8738–
8749; h) W.-K. Kim, M. J. Fevola, L. M. Liable-Sands, A. L.
Rheingold, K. H. Theopold, Organometallics 1998, 17, 4541–
4543; i) J. Zhang, Z. Ke, F. Bao, J. Long, H. Gao, F. Zhu, Q.
Wu, J. Mol. Catal. A 2006, 249, 31–39; j) J. Feldman, S. J.
McLain, A. Parthasarathy, W. J. Marshall, J. C. Calabrese,
S. D. Arthur, Organometallics 1997, 16, 1514–1516; k) J. A.
Olson, T. A. P. Paulose, P. Wennek, J. W. Quail, S. R. Foley,
Inorg. Chem. Commun. 2008, 11, 1297–1299; l) S. Gong, H.
Ma, J. Huang, J. Organomet. Chem. 2008, 693, 3509–3518; m)
B. M. Chamberlain, M. Cheng, D. R. Moore, T. M. Ovitt,
E. B. Lobkovsky, G. W. Coates, J. Am. Chem. Soc. 2001, 123,
3229–3238; n) A. P. Dove, V. C. Gibson, E. L. Marshell, A. J. P.
White, D. J. Williams, Chem. Commun. 2001, 283–284; o)
M. H. Chisholm, J. C. Gallucci, K. Phomphrai, Inorg. Chem.
2004, 43, 6717–6725; p) S. Yao, S. Block, M. Brym, M. Driess,
Chem. Commun. 2007, 3844–3846; q) D. Vidovic, G. Reeske,
M. Findlater, A. H. Cowley, Dalton Trans. 2008, 2293–2297; r)
S. Yao, Y. Xiong, C. van Wüllen, M. Driess, Organometallics
2009, 28, 1610–1612; s) A. L. Kenward, W. E. Piers, M. Parvez,
Organometallics 2009, 28, 3012–3020; t) M. R. Crimmin,
A. G. M. Barrett, M. S. Hill, D. J. MacDougall, M. F. Mahon,
P. A. Procopiou, Dalton Trans. 2009, 9715–9717; u) X. Tian,
R. Goddard, K.-R. Pörschke, Organometallics 2006, 25, 5854–
5862; v) A. Hadzovic, J. Janetzko, D. Song, Dalton Trans. 2008,
3279–3281; w) A. Hadzovic, D. Song, Inorg. Chem. 2008, 47,
12010–12017; x) A. Hadzovic, D. Song, Organometallics 2008,
27, 1290–1298; y) P. B. Hitchcock, M. F. Lappert, M. Linnol-
ahti, R. Sablong, J. R. Severn, J. Organomet. Chem. 2009, 694,
667–676; z) B.-L. Lin, K. X. Bhattacharyya, J. A. Labinger,
J. E. Bercaw, Organometallics 2009, 28, 4400–4405.
General Procedure for the Suzuki Reaction: The prescribed amount
of catalyst, base (2 equiv.), phenylboronic acid (1.5 equiv.), and so-
lid aryl halides (1 equiv.) were placed in a Schlenk tube under nitro-
gen. Ethanol (0.5 mL), deionized water (1.5 mL), and liquid aryl
halides (1 equiv.) were added by syringe. The reaction mixture was
stirred at the prescribed temperature for the prescribed time. The
volatiles were removed, and the residue was diluted with ethyl acet-
ate and filtered through a pad of silica gel. A sample in CDCl3 was
taken for determination of conversion by NMR spectroscopy. The
crude material was further purified by flash chromatography on
silica gel (ethyl acetate/n-hexane).
General Procedure for the Heck Reaction: The prescribed amount
of catalyst, base (1.5 equiv.), and solid aryl halides (1 equiv.) were
placed in a Schlenk tube under nitrogen. Solvent (2 mL), styrene
(1.3 equiv.), and liquid aryl halides (1 equiv.) were added by syringe.
The reaction mixture was heated to the prescribed temperature for
the prescribed time. The volatiles were removed, and the residue
was dissolved in ethyl acetate and filtered through a pad of silica
gel. A sample in CDCl3 was taken for determination of conversion
by NMR spectroscopy. The crude material was further purified by
flash chromatography on silica gel (ethyl acetate/n-hexane).
Crystal Structure Data: Crystals were grown from concentrated
CH2Cl2/n-hexane solutions (for 4–8 and 7Ј) or n-hexane solutions
(for 1 and 2) and isolated by filtration. Suitable crystals of 1–5, 7Ј,
and 8 were sealed in thin-walled glass capillaries under a nitrogen
atmosphere and mounted on a Bruker AXS SMART 1000 dif-
fractometer. Suitable crystals of 6 and 7 were mounted on a
Mounted CryoLoop (Hampton Research, size: 0.5–0.7 mm) using
perfluoropolyether vacuum oil (Aldrich, Fomblin®Y) and cooled
rapidly in a stream of cold nitrogen gas using an Oxford Diffraction
Limited GEMINT R and S. For 1–5, 7Ј, and 8, the absorption
correction was based on the symmetry equivalent reflections using
[2] a) A. R. Siedle, R. J. Webb, F. E. Behr, R. A. Newmark, D. A.
Weil, K. Erickson, R. Naujok, M. Brostrom, M. Mueller, S.-
Eur. J. Inorg. Chem. 2011, 5182–5195
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5193

K.-F. Peng, C.-T. Chen
FULL PAPER
H. Chou, V. G. Young Jr., Inorg. Chem. 2003, 42, 932–934; b)
N. Heβe, R. Fröhlich, I. Humelnicu, E.-U. Würthwein, Eur. J.
Inorg. Chem. 2005, 2189–2197; c) J.-P. Guo, W.-K. Wong, W.-
Y. Wong, Eur. J. Inorg. Chem. 2006, 3634–3640; d) J.-B. Grev-
ing, H. Behrens, R. Fröhlich, E.-U. Würthwein, Eur. J. Org.
Chem. 2008, 5740–5754; e) I. Häger, R. Fröhlich, E.-U.
Würthwein, Eur. J. Inorg. Chem. 2009, 2415–2428; f) M. N. Ko-
pylovich, J. Lasri, M. F. C. Guedes da Silva, A. J. L. Pombeiro,
Dalton Trans. 2009, 3074–3084; g) M. N. Kopylovich, J. Lasri,
M. F. C. Guedes da Silva, A. J. L. Pombeiro, Eur. J. Inorg.
Chem. 2011, 377–383; h) H. V. R. Dias, S. Singh, Inorg. Chem.
2004, 43, 5786–5788; i) H. V. R. Dias, S. Singh, Inorg. Chem.
2004, 43, 7396–7402; j) H. V. R. Dias, S. Singh, J. A. Flores,
Inorg. Chem. 2006, 45, 8859–8861; k) M. Zhou, Y. Song, T.
Gong, H. Tong, J. Guo, L. Weng, D. Liu, Inorg. Chem. 2008,
47, 6692–6700; l) P. J. Figiel, M. N. Kopylovich, J. Lasri,
M. F. C. Guedes da Silva, J. J. R. Fraústo da Silva, A. J. L.
Pombeiro, Chem. Commun. 2010, 46, 2766–2768; m) M. Zhou,
T. Gong, X. Qiao, H. Tong, J. Guo, D. Liu, Inorg. Chem. 2011,
50, 1926–1930.
1667–1670; g) C.-T. Chen, C.-Y. Chan, C.-A. Huang, M.-T.
Chen, K.-F. Peng, Dalton Trans. 2007, 4073–4078; h) C.-T.
Chen, H.-J. Weng, M.-T. Chen, C.-A. Huang, K.-F. Peng, Eur.
J. Inorg. Chem. 2009, 2129–2135; i) M.-T. Chen, P.-J. Chang,
C.-A. Huang, K.-F. Peng, C.-T. Chen, Dalton Trans. 2009,
9068–9074; j) V. Coeffard, H. Müller-Bunz, P. J. Guiry, Org.
Biomol. Chem. 2009, 7, 1723–1734; k) M. Yamashita, Y. Ara-
maki, K. Nozaki, New J. Chem. 2010, 34, 1774–1782; l) I. Ki-
eltsch, G. G. Dubinina, C. Hamacher, A. Kaiser, J. Torres-Ni-
eto, J. M. Hutchison, A. Klein, Y. Budnikova, D. A. Vicic, Or-
ganometallics 2010, 29, 1451–1456.
a) I. Aiello, A. Crispini, M. Ghedini, M. L. Deda, F. Barigel-
letti, Inorg. Chim. Acta 2000, 308, 121–128; b) N. Maiti, S. Pal,
S. Chattopadhyay, Inorg. Chem. 2001, 40, 2204–2205; c) C.-W.
Su, J.-D. Chen, T.-C. Keng, J.-C. Wang, Inorg. Chem. Commun.
2001, 4, 201–204; d) R. J. Bowen, M. A. Fernandes, M. Layh,
J. Organomet. Chem. 2004, 689, 1230–1237; e) Z. Zhu, M. Ko-
jima, K. Nakajima, Inorg. Chim. Acta 2005, 358, 476–488; f)
D. Patra, J. Pratihar, B. Shee, P. Pattanayak, S. Chattopadhyay,
Polyhedron 2006, 25, 2637–2642; g) J. Pratihar, B. Shee, P. Pat-
tanayak, D. Patra, A. Bhattacharyya, V. G. Puranik, C. H.
Hung, S. Chattopadhyay, Eur. J. Inorg. Chem. 2007, 4272–4281;
h) M. Zhang, M. Inamo, M. Kojima, K. Nakajima, Inorg.
Chim. Acta 2007, 360, 3040–3046; i) A. R. Dick, M. S. Remy,
J. W. Kampf, M. S. Sandford, Organometallics 2007, 26, 1365–
1370; j) T. Furuya, H. M. Kaiser, T. Ritter, Angew. Chem. 2008,
120, 6082; Angew. Chem. Int. Ed. 2008, 47, 5993–5996; k) T.
Furuya, T. Ritter, J. Am. Chem. Soc. 2008, 130, 10060–10061.
a) N. Thirupathi, D. Amoroso, A. Bell, J. D. Protasiewicz, Or-
ganometallics 2005, 24, 4099–4102; b) J.-C. Lee, M.-G. Wang,
F.-E. Hong, Eur. J. Inorg. Chem. 2005, 5011–5017; c) B.-Y.
Shiu, P.-C. Huang, Y.-L. Huang, F.-E. Hong, Tetrahedron 2008,
64, 6221–6229; d) L.-Y. Jung, S.-H. Tsai, F.-E. Hong, Organo-
metallics 2009, 28, 6044–6053; e) C. C. Scarborough, A.
Bergant, G. T. Sazama, I. A. Guzei, L. C. Spencer, S. S. Stahl,
Tetrahedron 2009, 65, 5084–5092; f) L. Ackermann, H. K. Po-
tukuchi, A. R. Kapdi, C. Schulzke, Chem. Eur. J. 2010, 16,
3300–3303.
[6]
[3] a) J. B. Gilroy, M. J. Ferguson, R. McDonald, B. O. Patrick,
R. G. Hicks, Chem. Commun. 2007, 126–128; b) J. B. Gilroy,
B. O. Patrick, R. McDonald, R. G. Hicks, Inorg. Chem. 2008,
47, 1287–1294; c) J. B. Gilroy, M. J. Ferguson, R. McDonald,
R. G. Hicks, Inorg. Chim. Acta 2008, 361, 3388–3393; d) S.
Hong, L. M. R. Hill, A. K. Gupta, B. D. Naab, J. B. Gilroy,
R. G. Hicks, C. J. Cramer, W. B. Tolman, Inorg. Chem. 2009,
48, 4514–4523; e) A. V. Zaidman, I. G. Pervova, A. I. Vilms,
G. P. Belov, R. R. Kayumov, P. A. Slepukhin, I. N. Lipunov,
Inorg. Chim. Acta 2011, 367, 29–34.
[7]
[4] a) J. Sanmartín, A. M. García-Deibe, M. R. Bermejo, F. Novio,
D. Navarro, M. Fondo, Eur. J. Inorg. Chem. 2003, 3905–3913;
b) I. Bar-Nahum, J. T. York, V. G. Young Jr., W. B. Tolman,
Angew. Chem. 2008, 120, 543; Angew. Chem. Int. Ed. 2008, 47,
533–536; c) B. Y. Lee, H. Y. Kwon, S. Y. Lee, S. J. Na, S.-I. Han,
H. Yun, H. Lee, Y.-W. Park, J. Am. Chem. Soc. 2005, 127,
3031–3037; d) H. Gao, W. Guo, F. Bao, G. Gui, J. Zhang, F.
Zhu, Q. Wu, Organometallics 2004, 23, 6273–6280; e) H.-Y.
Wang, X. Meng, G.-X. Jin, Dalton Trans. 2006, 2579–2585; f)
H. Gao, Z. Ke, L. Pei, K. Song, Q. Wu, Polymer 2007, 48,
7249–7254; g) J. Long, H. Gao, K. Song, F. Liu, H. Hu, L.
Zhang, F. Zhu, Q. Wu, Eur. J. Inorg. Chem. 2008, 4296–4305;
h) D. Zhang, Q. Yue, J. Wang, G. Shigeng, L. Weng, Inorg.
Chem. Commun. 2009, 12, 1193–1196; i) T. Xu, H. An, W. Gao,
Y. Mu, Eur. J. Inorg. Chem. 2010, 3360–3364; j) W. Gao, D.
Cui, X. Liu, Y. Zhang, Y. Mu, Organometallics 2008, 27, 5889–
5893; k) W. Yao, Y. Mu, A. Gao, W. Gao, L. Ye, Dalton Trans.
2008, 3199–3206; l) Y.-H. Tsai, C.-H. Lin, C.-C. Lin, B.-T. Ko,
J. Polym. Sci., Part A: Polym. Chem. 2009, 47, 4927–4936; m)
A.-H. Gao, W. Yao, Y. Mu, W. Gao, M.-T. Sun, Q. Su, Polyhe-
dron 2009, 28, 2605–2610; n) R. M. Porter, A. A. Danopoulos,
Dalton Trans. 2004, 2556–2562; o) Y. Ren, X. Liu, W. Gao, H.
Xia, L. Ye, Y. Mu, Eur. J. Inorg. Chem. 2007, 1808–1814; p)
S. M. Kloek, K. I. Goldberg, J. Am. Chem. Soc. 2007, 129,
3460–3461; q) E. C. Brown, I. Bar-Nahum, J. T. York, N. W.
Aboelella, W. B. Tolman, Inorg. Chem. 2007, 46, 486–496; r) A.
Mcheik, N. Katir, A. Castel, H. Gornitzka, S. Massou, P. Ri-
vière, T. Hamieh, Eur. J. Inorg. Chem. 2008, 5397–5403; s) X.
Meng, Y.-J. Lin, G.-X. Jin, J. Organomet. Chem. 2008, 693,
2597–2602; t) K. Pang, Y. Rong, G. Parkin, Polyhedron 2010,
29, 1881–1890.
[8]
a) J. Ruiz, M. T. Martínez, C. Vicente, G. García, G. López,
P. A. Chaloner, P. B. Hitchcock, Organometallics 1993, 12,
4321–4326; b) L. A. Villanueva, K. A. Abboud, J. M. Boncella,
Organometallics 1994, 13, 3921–3931; c) F. Ragaini, S. Cenini,
F. Demartin, J. Chem. Soc., Dalton Trans. 1997, 2855–2856; d)
S. Kannan, J. P. R. Sharp, Polyhedron 2000, 19, 155–163; e) A.
Singh, U. Anandhi, M. A. Cinellu, P. R. Sharp, Dalton Trans.
2008, 2314–2327.
[9]
J. V. Cuevas, G. García-Herbosa, A. Muñoz, Organometallics
1997, 16, 2220–2222.
[10]
a) A. Fernádez, D. Vázquez-García, J. J. Fernández, M. López-
Torres, A. Suárez, S. Castro-Juiz, J. M. Vila, Eur. J. Inorg.
Chem. 2002, 2389–2401; b) M. López-Torres, P. Juanatey, J. J.
Fernández, A. Fernádez, A. Suárez, R. Mosteiro, J. M. Ortig-
ueira, J. M. Vila, Organometallics 2002, 21, 3628–3636; c) N. R.
Conley, L. A. Labios, D. M. Pearson, C. C. L. McCrory, R. M.
Wagmouth, Organometallics 2007, 26, 5447–5453; d) O. Siri, P.
Braunstein, J.-P. Taquet, J.-P. Collin, R. Welter, Dalton Trans.
2007, 1481–1483; e) K.-F. Peng, M.-T. Chen, C.-A. Huang, C.-
T. Chen, Eur. J. Inorg. Chem. 2008, 2463–2470; f) M.-T. Chen,
C.-A. Huang, C.-T. Chen, Eur. J. Inorg. Chem. 2008, 3142–
3150.
[11]
[12]
a) H. Weissman, L. J. W. Shimon, D. Milstein, Organometallics
2004, 23, 3931–3940; b) J. J. Nuricumbo-Escobar, C. Campos-
Alvarado, G. Ríos-Moreno, D. Morales-Morales, P. J. Walsh,
M. Parra-Hake, Inorg. Chem. 2007, 46, 6182–6189; c) D. L.
Davies, O. Al-Duaij, J. Faecett, K. Singh, J. Organomet. Chem.
2008, 693, 965–980; d) J. Vicente, A. Arcas, F. Juliá-Hernández,
Organometallics 2010, 29, 3066–3076.
a) C. W. Liu, T. S. Lobana, B. K. Santra, C.-M. Hung, H.-Y.
Liu, B.-J. Liaw, J.-C. Wang, Dalton Trans. 2006, 560–570; b) G.
Tresoldi, S. Lanza, S. D. Pietro, D. Drommi, Eur. J. Inorg.
[5] a) M. Cheng, N. A. Darling, E. B. Lobkovsky, G. W. Coates,
Chem. Commun. 2000, 2007–2008; b) J. Castro, S. Cabaleiro, P.
Pérez-Lourido, J. Romero, J. A. García-Vázquez, A. Sousa, Z.
Anorg. Allg. Chem. 2002, 628, 1210–1217; c) A. Decken, R. A.
Gossage, P. N. Yadav, Can. J. Chem. 2005, 83, 1185–1189; d)
K.-M. Wu, C.-A. Huang, K.-F. Peng, C.-T. Chen, Tetrahedron
2005, 61, 9679–9687; e) S. Doherty, J. G. Knight, C. H. Smyth,
N. T. Sore, R. K. Rath, W. McFarlane, R. W. Harrington, W.
Clegg, Organometallics 2006, 25, 4341–4350; f) R. Giri, N.
Maugel, B. M. Foxman, J.-Q. Yu, Organometallics 2008, 27,
5194
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 5182–5195

Palladium Complexes Containing Anilido-Oxazolinate Ligands
Chem. 2008, 4807–4815; c) E. Hauptman, P. J. Fagan, W. Mar-
shall, Organometallics 1999, 18, 2061–2073; d) J. Dupont, A. S.
Gruber, G. S. Fonseca, A. L. Monteiro, G. Ebeling, R. A. Bur-
row, Organometallics 2001, 20, 171–176.
694, 3008–3011; o) A. Kumar, M. Agarwal, A. K. Singh, R. J.
Butcher, Inorg. Chim. Acta 2009, 362, 3208–3218; p) S. A. Patil,
C.-M. Weng, P.-C. Huang, F.-E. Hong, Tetrahedron 2009, 65,
2889–2897; q) J. Cui, M. Zhang, Y. Zhang, Inorg. Chem. Com-
mun. 2010, 13, 81–85; r) P. Liu, X.-J. Feng, R. He, Tetrahedron
2010, 66, 631–636; s) N. S. Nandurkar, B. M. Bhanage, Tetrahe-
dron 2008, 64, 3655–3660.
[13] a) N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457–2483; b)
S. P. Stanforth, Tetrahedron 1998, 54, 263–303; c) A. Suzuki, J.
Organomet. Chem. 1999, 576, 147–168; d) I. P. Beletskaya, A. V.
Cheprakov, Chem. Rev. 2000, 100, 3009–3066; e) N. J. Whit-
combe, K. K. Hii, S. E. Gibson, Tetrahedron 2001, 57, 7449–
7476; f) A. F. Littke, G. C. Fu, Angew. Chem. 2002, 114, 4350;
Angew. Chem. Int. Ed. 2002, 41, 4176–4211; g) S. Kotha, K.
Lahiri, D. Kashinath, Tetrahedron 2002, 58, 9633–9695; h)
R. B. Bedford, Chem. Commun. 2003, 1787–1796; i) E.-I. Negi-
shi, L. Anastasia, Chem. Rev. 2003, 103, 1979–2017; j) W. A.
Herrmann, K. Öfele, D. V. Preysing, S. K. Schneider, J. Or-
ganomet. Chem. 2003, 687, 229–248; k) H.-U. Blaser, A. In-
dolese, F. Naud, U. Nettekoven, A. Schnyder, Adv. Synth. Ca-
tal. 2004, 346, 1583–1598; l) R. B. Bedford, C. S. J. Cazin, D.
Holder, Coord. Chem. Rev. 2004, 248, 2283–2321; m) U.
Christmann, R. Vilar, Angew. Chem. 2005, 117, 370; Angew.
Chem. Int. Ed. 2005, 44, 366–374; n) A. C. Frisch, M. Beller,
Angew. Chem. 2005, 117, 680; Angew. Chem. Int. Ed. 2005, 44,
674–688; o) K. C. Nicolaou, P. G. Bulger, D. Sarlah, Angew.
Chem. 2005, 117, 4516; Angew. Chem. Int. Ed. 2005, 44, 4442–
4489; p) A. Zapf, M. Beller, Chem. Commun. 2005, 431–440;
q) N. T. S. Phan, M. Van Der Sluys, C. W. Jones, Adv. Synth.
Catal. 2006, 348, 609–679; r) J.-P. Corbet, G. Mignani, Chem.
Rev. 2006, 106, 2651–2710; s) H. Doucet, J.-C. Hierso, Angew.
Chem. 2007, 119, 850; Angew. Chem. Int. Ed. 2007, 46, 834–
871; t) L. Yin, J. Liebscher, Chem. Rev. 2007, 107, 133–173; u)
R. Chinchilla, C. Nájera, Chem. Rev. 2007, 107, 874–922; v)
A. M. Trzeciak, J. J. Ziółkowski, Coord. Chem. Rev. 2007, 251,
1281–1293; w) G. P. McGlacken, I. J. S. Fairlamb, Eur. J. Org.
Chem. 2009, 4011–4029; x) G. A. Molander, B. Canturk, An-
gew. Chem. 2009, 121, 9404; Angew. Chem. Int. Ed. 2009, 48,
9240–9261; y) S. E. Denmark, C. R. Butler, Chem. Commun.
2009, 20–33; z) L. Xue, Z. Lin, Chem. Soc. Rev. 2010, 39, 1692–
1705.
[17]
a) S. Iyer, G. M. Kulkarni, C. Ramesh, Tetrahedron 2004, 60,
2163–2172; b) Y. Kawashita, C. Ueba, M. Hayashi, Tetrahedron
Lett. 2006, 47, 4231–4233; c) C. Mazet, L. H. Gade, Organome-
tallics 2001, 20, 4144–4146; d) B. Tao, D. W. Boykin, Tetrahe-
dron Lett. 2002, 43, 4955–4957; e) R. A. Gossage, H. A. Jenk-
ins, P. N. Yadav, Tetrahedron Lett. 2004, 45, 7689–7691; f) C. R.
Eisnor, R. A. Gossage, P. N. Yadav, Tetrahedron 2006, 62,
3395–3401; g) X.-Q. Hao, Y.-N. Wang, J.-R. Liu, K.-L. Wang,
J.-F. Gong, M.-P. Song, J. Organomet. Chem. 2009, 695, 82–
89; h) V. A. Stepanova, J. E. Kukowski, I. P. Smoliakova, Inorg.
Chem. Commun. 2010, 13, 653–655; i) T. Kawano, T. Shinom-
aru, I. Ueda, Org. Lett. 2002, 4, 2545–2547; j) C. Nájera, J.
Gil-Moltó, S. Karlström, L. R. Falvello, Org. Lett. 2003, 5,
1451–1454; k) C. Nájera, J. Gil-Moltó, S. Karlström, Adv.
Synth. Catal. 2004, 346, 1798–1811; l) W.-Y. Wu, S.-N. Chen,
F.-Y. Tsai, Tetrahedron Lett. 2006, 47, 9267–9270; m) X. Cui,
J. Li, Z.-P. Zhang, Y. Fu, L. Liu, Q.-X. Guo, J. Org. Chem.
2007, 72, 9342–9345; n) A. Mukherjee, A. Sarkar, Tetrahedron
Lett. 2005, 46, 15–18; o) F. Li, T. S. A. Hor, Adv. Synth. Catal.
2008, 350, 2391–2400; p) V. Montoya, J. Pons, V. Branchadell,
J. Garcia-Antón, X. Solans, M. Font-Bardía, J. Ros, Organome-
tallics 2008, 27, 1084–1091; q) A. Pal, R. Ghosh, N. N. Adarsh,
A. Sarkar, Tetrahedron 2010, 66, 5451–5458; r) S. O. Ojwach,
J. Darkwa, Inorg. Chim. Acta 2010, 363, 1947–1964; s) S. B.
Park, H. Alper, Org. Lett. 2003, 5, 3209–3212; t) W. Chen, C.
Xi, Y. Wu, J. Organomet. Chem. 2007, 692, 4381–4388; u) K.
Kawamura, S. Haneda, Z. Gan, K. Eda, M. Hayashi, Organo-
metallics 2008, 27, 3748–3752; v) J.-H. Li, W.-J. Liu, Org. Lett.
2004, 6, 2809–2811; w) J.-H. Li, W.-J. Liu, Y.-X. Xie, J. Org.
Chem. 2005, 70, 5409–5412; x) J.-H. Li, X.-C. Hu, Y. Liang,
Y.-X. Xie, Tetrahedron 2006, 62, 31–38; y) S. Mohanty, D. Su-
resh, M. S. Balakrishna, J. T. Mague, Tetrahedron 2008, 64,
240–247; z) S. Mohanty, D. Suresh, M. S. Balakrishna, J. T.
Mague, J. Organomet. Chem. 2009, 694, 2114–2121.
[14] a) M.-N. Birkholz, Z. Freixa, P. W. N. M. van Leeuwen, Chem.
Soc. Rev. 2009, 38, 1099–1118; b) C. A. Fleckenstein, H. Plenio,
Chem. Soc. Rev. 2010, 39, 694–711.
[15] a) W. A. Herrmann, Angew. Chem. 2002, 114, 1342; Angew.
Chem. Int. Ed. 2002, 41, 1290–1309; b) E. Peris, R. H. Crabtree,
Coord. Chem. Rev. 2004, 248, 2239–2246; c) C. M. Crudden,
D. P. Allen, Coord. Chem. Rev. 2004, 248, 2247–2273; d)
E. A. B. Kantchev, C. J. O’Brien, M. G. Organ, Angew. Chem.
2007, 119, 2824; Angew. Chem. Int. Ed. 2007, 46, 2768–2813.
[16] a) S. Li, Y. Lin, J. Cao, S. J. Zhang, Org. Chem. 2007, 72, 4067–
4072; b) K. Lamm, M. Stollenz, M. Meier, H. Görls, D. Wal-
ther, J. Organomet. Chem. 2003, 681, 24–36; c) S. Rau, K.
Lamm, H. Görls, J. Schöffel, D. Walther, J. Organomet. Chem.
2004, 689, 3582–3592; d) Z. Weng, S. Teo, L. L. Koh, T. S. A.
Hor, Organometallics 2004, 23, 3603–3609; e) S. Gülcemal, Í.
Kani, F. Yilmaz, B. Çetinkaya, Tetrahedron 2010, 66, 5602–
5606; f) G. A. Grasa, A. C. Hillier, S. P. Nolan, Org. Lett. 2001,
3, 1077–1080; g) D. Domin, D. Benito-Garagorri, K. Mereiter,
J. Fröhlch, K. Kirchner, Organometallics 2005, 24, 3957–3965;
h) T. Mino, Y. Shirae, M. Sakamoto, T. Fujita, J. Org. Chem.
2005, 70, 2191–2194; i) T. Kylmälä, N. Kuuloja, Y. Xu, K. Ris-
sanen, R. Franzén, Eur. J. Org. Chem. 2008, 4019–4024; j) B.
Tao, D. W. Boykin, Tetrahedron Lett. 2003, 44, 7993–7996; k)
B. Tao, D. W. Boykin, J. Org. Chem. 2004, 69, 4330–4335; l)
Y.-C. Lai, H.-Y. Chen, W.-C. Hung, C.-C. Lin, F.-E. Hong,
Tetrahedron 2005, 61, 9484–9489; m) I. D. Kostas, B. R. Steele,
A. Terzis, S. V. Amosova, A. V. Martynov, N. A. Makhaeva,
Eur. J. Inorg. Chem. 2006, 2642–2646; n) D. F. Brayton, T. M.
Larkin, D. A. Vicic, O. Navarro, J. Organomet. Chem. 2009,
[18]
a) J. P. Genet, M. Savignac, J. Organomet. Chem. 1999, 576,
305–317; b) C.-J. Li, Chem. Rev. 2005, 105, 3095–3165; c) K. H.
Shaughnessy, Eur. J. Org. Chem. 2006, 1827–1835; d) K. H.
Shaughnessy, Chem. Rev. 2009, 109, 643–710; e) K. H. Shaugh-
nessy, R. S. Booth, Org. Lett. 2001, 3, 2757–2759; f) R. B. De-
Vasher, L. R. Moore, K. H. Shaughnessy, J. Org. Chem. 2004,
69, 7919–7927; g) N. A. Bumagin, V. V. Bykov, Tetrahedron
1997, 53, 14437–14450; h) I. Özdemir, S. Demir, B. Çetinkaya,
Tetrahedron 2005, 61, 9791–9798; i) L. Liu, Y. Zhang, B. Xin,
J. Org. Chem. 2006, 71, 3994–3997; j) Y. Kitamura, A. Sakurai,
T. Udzu, T. Maegawa, Y. Monguchi, H. Sajiki, Tetrahedron
2007, 63, 10596–10602; k) T. Maegawa, Y. Kitamura, S. Sako,
T. Udzu, A. Sakurai, A. Tanaka, Y. Kobayashi, K. Endo, U.
Bora, T. Kurita, A. Kozaki, Y. Monguchi, H. Sajiki, Chem.
Eur. J. 2007, 13, 5937–5943; l) B. Mu, T. Li, J. Li, Y. Wu, J.
Organomet. Chem. 2008, 693, 1243–1251; m) J. Wang, G. Song,
Y. Peng, Tetrahedron Lett. 2011, 52, 1477–1480.
[19] G. M. Sheldrick, SADABS, Program for area detector absorp-
tion correction, Institute for Inorganic Chemistry, University of
Göttingen, Germany, 1996.
[20] G. M. Sheldrick, SHELXTL-97, Program for refinement of
crystal structures, Institute for Inorganic Chemistry, University
of Göttingen, Germany, 1997.
Received: July 18, 2011
Published Online: October 17, 2011
Eur. J. Inorg. Chem. 2011, 5182–5195
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5195