Synthesis, reactivity and characterization of mono-, bi- and tri-nuclear Schiff-base palladacycles with aromatic N-heterocycles

Article abstract of DOI:10.1016/j.jorganchem.2012.04.026

Reactions of μ₂-Chloro bridged cyclometallated Pd(II) complexes [Pd{(4-R) C₆H₃CHNC₆H ₃-2,6-i-Pr₂}(μ-Cl)]₂ (R = H, OMe) with aromatic N-heterocycles such as 1-methylimidazole, 4,4

Full text of DOI:10.1016/j.jorganchem.2012.04.026

Journal of Organometallic Chemistry 713 (2012) 134e142
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, reactivity and characterization of mono-, bi- and tri-nuclear Schiff-base
palladacycles with aromatic N-heterocycles
,
a
a
a
a
a
Xiaohong Chang a , Yu Wang , Yuchun Jiang , Yonglin Guo , Dandan Song , Ximing Song ,
*
,
c
Francis Verpoort b
a Liaoning Provincial Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, PR China
b State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, PR China
c Department of Inorganic and Physical Chemistry, Laboratory of Organometallic Chemistry and Catalysis, Ghent University, Krijgslaan 281 (S-3), 9000 Ghent, Belgium
a r t i c l e i n f o
a b s t r a c t
Article history:
Reactions of m2-Chloro bridged cyclometallated Pd(II) complexes [Pd{(4-R) C6H3CH]NC6H3-2,6-i-Pr2}(m-
Cl)]2 (R ¼ H, OMe) with aromatic N-heterocycles such as 1-methylimidazole, 4,40-bipyridyl (bpy), 1,2-
bis(4-pyridyl)-ethene (bpe), 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (bpt) and 2,4,6-tris-(4-pyridyl)-1,3,5-
triazine (tpt), generated mononuclear complexes [Pd{(4-R)C6H3CH]NC6H3-2,6-i-Pr2}(L)(Cl)] (L ¼ 1-
Received 10 March 2012
Received in revised form
23 April 2012
Accepted 25 April 2012
methylimidazole, R ¼ H, OMe), binuclear complexes [Pd{(4-R)C6H3CH]NC6H3-2,6-i-Pr2}(Cl)]2(
m-Y)
(R ¼ H, OMe; Y ¼ bpy, bpe, bpt) and trinuclear complexes [Pd{(4-R) C6H3CH]NC6H3-2,6-i-Pr2}(Cl)]3(tpt)
(R ¼ H, OMe). In contrast, the reaction of m2-Chloro bridged cyclometallated Pd(II) complexes [Pd{(4-R)
Keywords:
Palladacycle
Schiff-base
N-heterocycle
C6H3CH]NC6H3-2,6-i-Pr2}(
produce binuclear cyclometallated Pd(II) nitrato complexes [Pd{(4-R) C6H3CH]NC6H3-2,6-i-Pr2}(O-
NO2)]2(
m
-Cl)]2 (R ¼ H, OMe) with 2 equiv of AgNO3 and followed with bpy, bpe, bpt to
m
-Y) (R ¼ H, OMe; Y ¼ bpy, bpe, bpt). Treatment of [Pd{(4-R)C6H3CH]NC6H3-2,6-i-Pr2}(Cl)]3(tpt)
(R ¼ H, OMe) with an excess AgNO3 produced trinuclear cyclometallated Pd(II) nitrato complexes [Pd{(4-
R) C6H3CH]NC6H3-2,6-i-Pr2}(ONO2)]3(tpt) (R ¼ H, OMe). All these complexes were fully characterized by
FT-IR, NMR spectroscopy, elemental analysis and/or X-ray crystallography.
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
Interestingly, although Schiff-base palladacycles are one of the
most extensively studied areas in Pd-chemistry [27e33], cyclo-
In the last few decades, the assemblies of organometallic
supramoleculars have attracted more and more interest because of
their potential application as promising molecular materials
[1e11]. The square planar species of platinum(II) and palladium(II)
have been extensively exploited to generate supramolecular
assemblies due to their rigid coordination environment [12e22]. It
is worth noticing that in most examples the blocking ligands bound
to platinum or palladium centers are symmetric diamines or
diphosphines. However, cyclometallated Pd(II) or Pt(II) complexes
containing C,N-donor ligands as corner species to assemble
supramoleculars are very limited [23e26]. In our opinion, readily
synthesized m2-chloro bridged dinuclear cyclometallated Pd(II)
metallated Pd(II) complexes incorporating Schiff-base and aromatic
N-heterocycles are rarely explored. Herein, we report reactions of
m2-chloro bridged dinuclear cyclometallated Pd(II) complexes [Pd
{(4-R)C6H3CH]N-C6H3-2,6-i-Pr2}(m-Cl)]2 with aromatic N-hetero-
cycles. Studies of resulting mono-, bi- and tri-nuclear Schiff-base
palladacycles with aromatic N-heterocycles as building blocks
toward supramolecular construction are in progress.
2. Results and discussion
2.1. Reactions of m-chloro bridged dinuclear cyclometallated Pd(II)
complexes with mono-, bi-, tri-dentate aromatic N-heterocycles
complexes [Pd{(4-R)C6H3CH]N-C6H3-2,6-i-Pr2}(
m
-Cl)]2 (R ¼ H, 1;
OMe, 2), with two blocked cis-coordination sites, seemed suitable
for assembling of metal macrocycles, if one could bridge the [Pd{(4-
R)C6H3CH]NC6H3-2,6-i-Pr2}]þ fragments by appropriate linkers.
Recently, we reported that m2-chloro bridged dinuclear cyclo-
metallated Pd(II) complexes [Pd{(4-R)C6H3CH]NC6H3-2,6-i-
Pr2}(
m
-Cl)]2 (R ¼ H,1; OMe, 2) can readily synthesized by reaction of
Na2PdCl4 with corresponding Schiff base [34]. Although cleavage of
the Cl-bridged cyclopalladated complexes by phosphines giving
neutral or ionic complexes is known [29,35,36], the reports of Cl-
bridged cyclopalladated complexes cleaved by aromatic N-
* Corresponding author. Tel.: þ86 24 62207823; fax: þ86 24 62202380.
E-mail addresses: cxh@lnu.edu.cn, c_x_hong@sina.com (X. Chang).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2012.04.026

X. Chang et al. / Journal of Organometallic Chemistry 713 (2012) 134e142
135
heterocycles are rare [37e39]. Consequently, we examined
the reactions of m2-chloro bridged dinuclear cyclometallated
Pd(II) complex 1 and 2 with mono-, bi- and tri-dentate aromatic
N-heterocycles, as shown in Scheme 1. Treatment of complex 1
and 2 with 2 equiv 1-methylimidazole in CH2Cl2 at room temper-
ature produced yellow mononuclear cyclometallated Pd(II)
complexes [Pd{(4-R)C6H3CH]N-C6H3-2,6-i-Pr2}(L)(Cl)] (L ¼ 1-
methylimidazole, R ¼ H, 3; L ¼ 1-methylimidazole, R ¼ OMe, 4).
The IR spectra of 3 and 4 showed a strengthened stretching at
approximately 1602 cmꢀ1 and 1599 cmꢀ1, respectively, due to the
v(C]N). The 1H NMR spectra of 3 and 4 displayed the resonance for
CH]N protons at
shifted downfield compared to the corresponding Cl-bridged
cyclopalladated complexes 1 and 2, respectively 7.74 ppm and
7.61 ppm. Moreover, upfield shift of the aromatic proton H3 of
d 7.91 and d 7.78 ppm, respectively, which was
d
d
palladated ring in the 1H NMR spectra of complexes 3 and 4 indi-
cated the cis disposition of 1-methylimidazole relative to metalated
carbon atom [35]. Interestingly, the 1H NMR spectra of 3 and 4
revealed the presence of two isomers (in the ratio of 1.00:0.41 for 3
and 1:0.23 for 4 based on the measured intensities of the signals
due to the CH]N groups), for major isomer, the Cl atom of PdeCl
bond is located in the trans-position of PdeC bond, and for minor
isomer, the Cl atom of PdeCl bond is located on the trans-position
of PdeN bond. However, the molecular structure of complex 3 only
exhibited one of the two isomers (Fig. 1).
ꢁ
ꢀ
Fig. 1. Molecular structure of 3. Selected bond lengths (A) and angles ( ): Pd1eC1
1.986(3), Pd1eN1 2.041(2), Pd1eCl1 2.4017(7), Pd1eN2 2.082(2); N1ePd1eN2
172.42(8), N1ePd1eCl1 94.96(6), N2ePd1eCl1 90.02(6), C1ePd1eCl1 176.03(8),
C1ePd1eN1 81.14(9).
blocking ligand. Therefore, we examined reactions of
m-chloro
Bearing in mind that
m-chloro bridged dinuclear cyclometallated
bridged dinuclear cyclometallated Pd(II) complexes 1 and 2 with
bidentate and tridentate aromatic N-heterocycles, such as 4,40-
bipyridyl (bpy), 1,2-bis(4-pyridyl)-ethene (bpe), 2,5-Bis(4-pyridyl)-
1,3,4-thiadiazole (bpt) and 2,4,6-tris-(4-pyridyl)-1,3,5-triazine(tpt).
As shown in Scheme 1, bidentate aromatic N-heterocycles (bpy,
Pd(II) complexes and
1
2
can be readily cleaved by 1-
methylimidazole, we decided to extend this cleavage reaction to
bidentate and tridentate aromatic N-heterocycles. We anticipated
that these reactions should afford binuclear and trinuclear cyclo-
metallated Pd(II) complexes containing C,N-Schiff base ligand as
R
R
R
CH3
N
N
Cl
N
Cl
N
Pd
N
N
Pd
HC
Pd
CH
HC
N
N
N
Cl
S
R = H, 9; OMe, 10
CH3
N
R = H, 3; OMe, 4
N
bpt
R
R
4'
N
5'
HC
R
3'
R
Cl
Cl
Cl
bpy
Pd
Pd
HC
CH
N
N
N
N
Pd
Pd
CH
N
6
5
Cl
3
R = H, 5; OMe, 6
tpt
R = H, 1; OMe, 2
R
Cl
HC
N
bpe
CH
Pd
N
Pd
Cl
N
N
R
N
N
R
R
N
N
Cl
Cl
N
Pd
CH
Pd
HC
N
N
Cl
N
Pd
N
HC
R = H, 11; OMe, 12
Scheme 1. Synthesis of mono-, bi- and tri-nuclear cyclometallated Pd(II) chloro complexes.
R
R = H, 7; OMe, 8

136
X. Chang et al. / Journal of Organometallic Chemistry 713 (2012) 134e142
bpe, bpt) stoichiometrically cleaved the
m
-chloro bridged dinuclear
Single crystals of 3 and 9 suitable for X-ray diffraction analysis
cyclometallated Pd(II) complexes 1 and 2 in CH2Cl2 at room
temperature to give N-heterocycles bridged dinuclear cyclo-
metallated Pd(II) complexes [Pd{(4-R)C6H3CH]NC6H3-2,6-i-Pr2}
were obtained from a dichloromethane/hexane solution and their
molecular structure is depicted in Figs. 1 and 2, respectively. Details
on crystal data, intensity collection, and refinement details are
given in Table 1. As shown in Fig. 1, 3 shows a slightly distorted
square-planar coordination containing a cyclometallated Schiff-
(Cl)]2(
m
-Y) (R ¼ H, Y ¼ bpy, 5; R ¼ OMe, Y ¼ bpy, 6; R ¼ H, Y ¼ bpe, 7;
R ¼ OMe, Y ¼ bpe, 8; R ¼ H, Y ¼ bpt, 9; R ¼ OMe, Y ¼ bpt, 10).
Complexes 5e10 were characterized by spectroscopy and
elemental analysis and the molecular structure of 9 was deter-
mined by X-ray crystallography. The 1H NMR spectra of 5e10
ꢀ
base ligand, a 1-methylimidazole and a Cl atom. N1 is 0.2032 A
out of the molecule planar, defined by C1, Pd1, Cl1 and N2. The five-
membered chelate ring that contains imine functionality defined
by Pd1, C1, C2, C7 and N1 is essentially planar with atomic
showed the resonances of dipyridyl protons at
7.03 ppm, 8.27 and 7.09 ppm, 8.12e8.19 and 7.04 ppm,
and 7.04 ppm, 8.33 and 7.59 ppm, 8.34 and 7.58 ppm,
d
8.21 and
ꢀ
d
d
d
d
d
d
8.14
displacements not exceeding 0.0530 A, to which the diisopropyl-
d
d
d
d
d
phenyl ring is roughly perpendicular with a dihedral angle
80.41(7)ꢁ. The smallest angle in coordination sphere of palladium
corresponds to the C1ePd1eN1 bite angle, 81.14(9)ꢁ. The Pd1eC1
respectively. The aromatic proton H3 of palladated ring in 1H NMR
spectra of complexes 5e10 was shifted to downfield compared to
that of complexes 3 and 4, indicating the trans disposition of
bipyridyl moieties in complexes 5e10 relative to metalated carbon
atom. Furthermore, this observation was confirmed by the molec-
ular structure of complex 9. Similarly to complexes 3 and 4, 1H NMR
spectra of 5e10 also revealed the presence of two isomers in
solution (in the ratio of 1.00:0.30 for 5, 1.00:0.23 for 6, 1.00:0.40 for
7, 1.00:0.27 for 8, 1.00:0.27 for 9, 1.00:0.17 for 10 based on the
measured intensities of the signals due to the CH]N groups). We
presumed the minor products were cis-isomers, in which the Cl
atom in PdeCl bond is located on the trans-position of PdeC bond,
based on the molecular structure of complex 9 (Fig. 2).
ꢀ
bond [1.986(3) A] is slightly longer compared to complex 1
ꢀ
ꢀ
[1.965(2) A] [30] and shorter than the calculated value of 2.05 A
based on the sum of the covalent radii of carbon and palladium.
This is consistent with the values for related complexes where
a partial multiple-bond character of PdeC was assumed [40e43].
An intermolecular CeH.Cl interaction between a proton of the 1-
methylimidazole ring and a chlorine atom coordinated to Pd atom
ꢀ
is observed, with a H.Cl distance of 2.861 A and a C.Cl distance of
ꢀ
3.666 A.
Moreover,
intramolecular
C14eH14.N1
and
C17eH17.N1 interactions are observed, with the distance of
ꢀ
ꢀ
ꢀ
H14.N1 2.4100 A, C14.N1 2.9035 A, H17.N1 2.4000 A, C17.N1
ꢀ
In contrast, the corresponding reactions of
m-chloro bridged
2.8796 A. Fig. 2 reveals that molecular of complex 9 has a dimeric
dinuclear cyclometallated Pd(II) complexes 1 and 2 with a stoi-
chiometric amount of tpt in CH2Cl2 at room temperature produced
trinuclear cyclometallated Pd(II) complexes [Pd(C6H4CH]N-C6H3-
2,6-i-Pr2)(Cl)]3(tpt) (11) and [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-
Pr2}(Cl)](tpt) (12), respectively. Complex 11 was characterized by
FT-IR spectrum and elemental analysis. However, 1H NMR of
complex 11 was not possible due to the poor solubility of 11 in
common organic solvents. The elemental analysis results were
structure bridged by m-bpt. The two Pd atoms are separated by
ꢀ
a distance of 15.054(1) A due to 2,5-bis(4-pyridyl)-1,3,4-thiadiazole
with two [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(Cl)] moieties taking the
cis conformation. Each Pd center adopts a slightly distorted square-
planar coordination containing
a cyclometallated Schiff-base
ligand, a bridging bpt ligand and a chlorine atom, the deviation
from the mean plane being 0.0333, 0.0346, ꢀ0.0011, 0.0061 and
0.0171 for C13, N5, Pd1, Cl1 and N1, respectively. The molecule
plane, defined by Pd1, C13, C18, C19 and N5 (plane 1), is relatively
consistent
with
the
formula
[Pd(C6H4CH]NC6H3-2,6-i-
Pr2)(Cl)]3(tpt). Complex 12 was characterized by FT-IR, 1H NMR and
planar with the atomic displacements not exceeding 0.0297 A. The
ꢀ
elemental analysis. 1H NMR spectrum of 12 showed the resonance
dihedral is 71.15(8)ꢁ between plane 1 and diisopropylphenyl ring,
and the dihedral amounts to 48.58(8)ꢁ between plane 1 and pyridyl
ring coordinated to Pd1. The structure of 9 also reveals that two
pyridyl rings of the bridging bpt ligand are not coplanar, being
twisted to each other by an angle of 18.07(10)ꢁ. The Pd1eC13 bond
approximately at
(CH]N group) and the resonances approximately at
d
7.87 ppm which is assigned to the imine proton
8.48 and
d
8.18 ppm which are assigned to pyridyl ring protons in tpt. Note-
worthy was that the H3 proton signal in complex 12 appeared at
ꢀ
lower field (
d
7.71 ppm), indicating that molecular of complex 12
length [1.989(3) A] is almost equal to the bond of complex 3. The
ꢀ
ꢀ
adopted a cis arrangement, in which the Cl atom in PdeCl bond was
located on the trans-position of PdeN bond and the pyridyl ring in
tpt, coordinating to Pd, was located on the trans-position of PdeC
bond. Furthermore, the 1H NMR spectra of 12 also revealed the
presence of two isomers (ratio of 1.00:0.23 based on the measured
intensities of the signals due to the CH]N groups).
Pd1eCl1 bond [2.2893(9) A] and Pd2eCl2 bond [2.3081(9) A] trans
to nitrogen in complex 9 are significantly shorter than that of
ꢀ
complex 3 [2.4017(7) A] trans to PdeC bond, indicating a higher
trans influence of the carbon. The similar C.Cl interaction as in
complex 3 between C9 of the pyridyl ring and a chlorine atom
ꢀ
coordinated to Pd atom is observed, with a distance of 3.641 A.
ꢁ
ꢀ
Fig. 2. Molecular structure of 9. Selected bond lengths (A) and angles ( ): Pd1eC131.989(3), Pd1eN1 2.181(3), Pd1eN5 2.051(3), Pd1eCl1 2.2893(9), Pd2eC32 1.988(3), Pd2eN4
2.156(3), Pd2eN6 2.037(3), Pd2eCl2 2.3081(9); C13ePd1eN1 177.42(12), C13ePd1eN5 80.42(13), N5ePd1eCl1 173.61(8), N1ePd1eCl1 88.84(7), N5ePd1eN1 97.43(10),
C32ePd2eN6 81.20(12), C32ePd2eN4, 172.40(13), N6ePd2eCl2 96.94(11), N4ePd2eCl2 88.25(8), N6ePd2eCl2 174.27(8).

X. Chang et al. / Journal of Organometallic Chemistry 713 (2012) 134e142
137
Table 1
X-ray data collection and structure refinement.
3
9$0.5C6H14$1.25CH2Cl2
13
21$4.775CH2Cl2
Formula
C23H28ClN3Pd
C54.25H61.50Cl4.50N6Pd2S
1201.98
113(2)
0.22 ꢂ 0.14 ꢂ 0.12
Monoclinic
P21/n
20.517(3)
11.6920(13)
25.107(3)
90
105.116(7)
90
C21H25N3O3Pd
473.84
293(2)
0.30 ꢂ 0.27 ꢂ 0.22
Monoclinic
P21/c
8.7730(18)
28.821(6)
9.1457(18)
90
112.87(3)
90
2130.7(7)
4
1.477
0.896
C82.77H93.54Cl9.55N12O12Pd3
2106.05
113(2)
Formula weight
Temperature (K)
Crystal size
488.33
296(2)
0.33 ꢂ 0.27 ꢂ 0.21
Monoclinic
P21/n
9.9869(7)
14.5976(10)
15.6445(10)
90
93.8620(10)
90
2275.6(3)
4
0.24 ꢂ 0.22 ꢂ 0.16
Crystal system
Space group
Triclinic
ꢁ
P ı
ꢀ
a, A
15.1786(17)
17.2424(19)
20.398(2)
77.838(11)
87.736(12)
69.511(11)
4885.0(9)
2
ꢀ
b, A
ꢀ
c, A
a
, deg
, deg
b
g
, deg
3
ꢀ
V, A
5814.4(12)
4
1.373
Z
dcal, g cmꢀ3
1.425
0.945
1.432
0.867
m
, mmꢀ1
0.900
F(000)
1000
2454
968
2141
Tmin
Tmax
0.338
0.475
16,872
4057
258
0.8266
0.8997
55,635
13,791
676
1.114
0.7748
0.8272
14,054
3823
258
0.763
0.8188
0.8737
49,077
22,777
1239
No. of reflns measured
No. of reflns unique
No. of params refined
ꢀꢀ3
Max., in Dr (e$A
)
0.274
1.530
ꢀꢀ3
Min., in Dr (e$A
)
ꢀ0.563
ꢀ0.796
ꢀ1.299
ꢀ1.936
GOF on F2
1.171
1.064
1.078
1.058
R (I > 2
s
(I))
wR2 (I > 2
R (all data)
0.0227
0.0783
0.0272
0.0949
0.0479
0.1290
0.0587
0.1363
0.0447
0.1028
0.0993
0.1617
0.0531
0.1296
0.0586
0.1337
a
s
(I))
a
wR2 (all data)
a
wR2 ¼ S[w(F2o ꢀ F2c)2]/S[w(F2o)2]1/2
.
Moreover, there are disordered crystallization solvent molecules
are found in molecular structure of complex 9.
protons at
d
9.12 and
d
7.69 ppm,
d
9.07 and
9.17 and
d
7.64 ppm, 9.01 and
8.09 ppm, d 9.13 and
d
d
7.93 ppm,
8.28 ppm,
d
9.00 and
9.28 and
d
7.93 ppm,
d
d
d
d
d
8.57 ppm, respectively, which were shifted
2.2. Bi- and tri-nuclear cyclometallated Pd(II) nitrato complexes
with aromatic N-heterocycle
downfield compared to those of the corresponding chloro coordi-
nated cyclopalladated complexes 5e10 and 12. The resonance of
the H3 protons in complexes 14e19 and 21 shifted upfield
compared to those of the corresponding chloro coordinated
cyclopalladated complexes 5e10 and 12. All these indications prove
that the configuration of complexes 14e21 was different from
corresponding complexes 5e12. The molecular structure of
complex 21 confirmed that the pyridyl fragments are located in
trans-position of PdeN bond and the O-bound nitrato groups are
located in trans-position of PdeC bond. Moreover, in contrast with
the spectra of 5e12, no isomers of the complexes 14e21 could be
detected in 1H NMR spectra.
Since nitrato ligand coordinated to Pd atom could be readily
substituted by other ligands for further supramolecular construc-
tion, bi- and tri-nuclear cyclometallated Pd(II) nitrato complexes, as
shown in Scheme 2 and Scheme 3 were prepared. Reacting
complexes 1 and 2 with 2 equiv of AgNO3 in CH3CN followed by
reaction with 4,40-bipyridyl or 1,2-bis(4-pyridyl)-ethene or 2,5-
bis(4-pyridyl)-1,3,4-thiadiazole in a 1:1 molar ratio in CH2Cl2 at
room temperature produced the binuclear cyclometallated Pd(II)
nitrato complexes [Pd{(4-R)C6H3CH]NC6H3-2,6-i-Pr2}(ONO2)]2(m-
Y) (R ¼ H, Y ¼ bpy, 14; R ¼ OMe, Y ¼ bpy, 15; R ¼ H, Y ¼ bpe, 16;
R ¼ OMe, Y ¼ bpe, 17; R ¼ H, Y ¼ bpt, 18; R ¼ OMe, Y ¼ bpt, 19).
Reacting complexes 11 and 12 with an excess of AgNO3 in CH2Cl2/
CH3OH at room temperature generated [Pd(C6H4CH]NC6H3-2,6-i-
Pr2)(ONO2)]3(tpt) (20) and [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-
Pr2}(ONO2)]3(tpt) (21), respectively. Moreover, the fully character-
ized complex 20 confirmed the formation of complex 11. Addi-
tionally, we were interested in the process of above reactions,
Single crystals of 13 and 21 suitable for X-ray diffraction analysis
were obtained from dichloromethane/hexane solutions and their
molecular structures are presented in Figs. 3 and 4, respectively.
Details on crystal data, intensity collection, and refinement details
are given in Table 1. Fig. 3 shows that palladium atom of complex 13
is in a square-planar environment containing a C,N-coordinating
Schiff-base ligand, one CH3CN, and one nitrato ligand. The coordi-
nation plane shows a tetrahedral distortion, the deviation from the
mean plane being ꢀ0.0012, ꢀ0.0609, 0.1794, 0.1163 and ꢀ0.0904
for Pd1, N1, C15, O1 and N3, respectively. The five-membered
chelate ring that contains imine functionality defined by Pd1, N1,
C13, C14 and C15 is essentially planar with the atomic displace-
therefore
the
intermediate
[Pd(C6H4CH]NC6H3-2,6-i-
Pr2)(NCCH3)(ONO2)] (13) was isolated (Scheme 4). The molecular
structure of complex 13 confirmed that it was a neutral monomeric
compound bearing one C,N-chelating Schiff-base ligand, one
CH3CN and one O-bound nitrato group, see Fig. 3. Complexes 13e21
were characterized by FT-IR, NMR and elemental analysis; more-
over the molecular structure of 13 and 21 was determined by X-ray
crystallography. The FT-IR spectra of 13e19 showed a strong band
at approximately 1384 cmꢀ1 due to the nNeO. The formation of
complexes 20 and 21 also was easily confirmed by characteristic
stretching band at 1384 cmꢀ1 deriving from the nitrato group. The
1H NMR spectra of 14e19 and 21 displayed the resonance of pyridyl
ꢀ
ments not exceeding 0.0174 A, to which the diisopropylphenyl ring
is roughly perpendicular with a dihedral angle 74.1(2)ꢁ. Pd1eN1
ꢀ
ꢀ
bond [2.025(6) A] and Pd1eN3 bond [2.022(7) A] lengths are
almost equal to each other. An intramolecular CeH.Pd between
the proton of isopropyl and palladium atom is observed, with
ꢀ
ꢀ
a H.Pd bond distance of 2.793 A and C.Pd distance of 3.639 A. As
presented in Fig. 4, complex 21 reveals that each Pd center has one
cyclometallated Schiff-base ligand, one terminal O-bound nitrato

138
X. Chang et al. / Journal of Organometallic Chemistry 713 (2012) 134e142
R
R
N
N
1. AgNO3
2. bpy
Pd
Pd
HC
R
CH
N
N
O2NO
ONO2
R = H, 14; OMe, 15
R
R
N
Cl
Cl
N
N
Pd
CH
Pd
1. AgNO3
2. bpe
HC
Pd
HC
R
Pd
CH
N
O2NO
N
ONO2
N
R = H, 16; OMe, 17
R
R
R = H, 1; OMe, 2
N
N
N
N
1. AgNO3
2. bpt
S
Pd
HC
Pd
CH
N
ONO2
N
O2NO
R = H, 18; OMe, 19
Scheme 2. Synthesis of binuclear cyclometallated Pd(II) nitrato complexes 14e19.
ligand and one tpt ligand. 2,4,6-Tris(4-pyridyl)-1,3,5-triazine links
three [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2} (ONO2)] moieties to
give three-dentate “clip” structure, the separation of Pd1.Pd2,
3. Experimental
3.1. General, materials and measurements
ꢀ
ꢀ
Pd2.Pd3 and Pd1. Pd3 is 12.761(1) A, 13.169(2) A and
ꢀ
13.126(2) A, respectively. The coordination sphere of each Pd can be
All manipulations of air-sensitive compounds were performed
under nitrogen by using standard Schlenk techniques. All solvents
were purified and degassed by standard procedure, other regents
were used as supplied. 1H NMR spectra were obtained using
a Mercury-300 spectrophotometer (Varian), CDCl3 or [d6]-DMSO
was applied for all compounds using TMS as an internal standard.
FT-IR spectra were recorded on a Nicolet AVATAR 330 FT-IR spec-
trometer. Elemental analyses were performed on a Thermo Flash
EA1112 Analyzer. ESI-MS was determined by Varian 500-MS ion
trap mass spectrometer equipped with an electrospray ionization
(ESI) source in positive ion mode, with data acquisition using the
Varian MS Workstation (Varian, Palo Alto, CA, USA).
described as slightly distorted square planar. The five-membered
chelate ring that contains the imine functionality defined by Pd1,
N6, C21, C22 and C27 is essentially planar with the atomic
ꢀ
displacements not exceeding 0.0339 A, to which the diisopropyl-
phenyl ring is roughly perpendicular with a dihedral angle 83.9(1)ꢁ.
The pyridyl rings are not coplanar with the triazine ring but they
are twisted to an angle of 12.1(9)ꢁ, 3.5(9)ꢁ and 6.6(9)ꢁ, respectively.
In summary, we prepared a number of mono-, bi- and tri-
nuclear cyclometallated Pd(II) chloro complexes containing C,N-
coordinating Schiff-base ligand by reactions of Cl-bridged cyclo-
palladated complexes with aromatic N-heterocycles. As well bi-
and tri-nuclear cyclometallated Pd(II) nitrato complexes were
synthesized. We found that bi- and tri-nuclear cyclometallated
Pd(II) nitrato complexes possess a different cis conformation with
corresponding bi- and tri-nuclear cyclometallated Pd(II) chloro
complexes in solid state. This kind of cis conformation should be
beneficial for assembling macrocycles based on bi- and tri-nuclear
cyclometallated Pd(II) nitrato complexes. Two kinds of intercon-
version isomers occurred in solution of bi- and tri-nuclear cyclo-
metallated Pd(II) chloro complexes. However, no isomers were
observed in solution of bi- and tri-nuclear cyclometallated Pd(II)
nitrato complexes.
[Pd(C6H4CH]NC6H3-2,6-i-Pr2)(
m-Cl)]2 and [Pd{(4-MeO)C6H3
CH]NC6H3-2,6-i-Pr2} (m-Cl)]2 were prepared according to literature
methods [34].
3.2. Preparations
3.2.1. [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(L)(Cl)](L ¼ 1-
methylimidazole) (3)
To a 10 mL CH2Cl2 solution of complex [Pd(C6H4CH]NC6H3-2,6-
i-Pr2)(m-Cl)]2 (1, 0.075 g, 0.092 mmol) was added stepwise 1-
methylimidazole (16
mL, 0.200 mmol). After stirring for 12 h at
R
Cl
N
N
O2NO
ONO2
HC
N
CH
HC
Pd
CH
Pd
Pd
N
Pd
Cl
N
N
N
N
N
N
N
R
N
N
N
N
R
R
AgNO3
N
Cl
CH2Cl2/CH3OH
R
Pd
O2NO Pd
N
N
HC
R
CH
R = H, 20; OMe, 21
R = H, 11; OMe, 12
Scheme 3. Synthesis of trinuclear cyclometallated Pd(II) nitrato complexes 20, 21.

X. Chang et al. / Journal of Organometallic Chemistry 713 (2012) 134e142
139
3.2.3. [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(Cl)]2(m-bpy) (5)
To a 10 mL CH2Cl2 solution of complex 1 (0.130 g, 0.160 mmol)
was dropwise added a CH2Cl2 solution of 4,40-Bipyridyl (0.037 g,
0.192 mmol). After stirring for 22 h at room temperature, the
solvent was completely evaporated, and the resulting residue was
washed with ether to give a pale yellow solid. Recrystallization
from CH2Cl2/hexane generated pale yellow crystals of
Cl
Cl
N
AgNO3
CH3CN
ONO2
N
Pd
HC
Pd
CH
13
HC
Pd
N
NCCH3
1
[Pd(C6H4CH]NC6H3-2,6-i-Pr2)(Cl)]2(m-bpy) (5, 0.090 g, 58%). IR
(KBr, cmꢀ1): 1600 ( C]N); 1H NMR (300 MHz in CDCl3,
n d): 8.21 (d,
Scheme 4. Synthesis of mononuclear cyclometallated Pd(II) nitrato complex 13.
4H, J ¼ 5.7 Hz, pyridyl), 8.06 (d, 2H, J ¼ 7.8 Hz, H3), 7.91 (s, 2H,
0
eHC]N), 7.34 (d, 2H, J ¼ 7.2 Hz, H6), 7.17e7.26 (m, 2H, H4 ), 7.08 (d,
room temperature, the solvent was completely evaporated and the
resulting residue was washed with ether to give a pale yellow solid.
Recrystallization from CH2Cl2/hexane generated pale yellow crys-
tals of [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(L)(Cl)](L ¼ 1-methylimida
4H, J ¼ 7.8 Hz, H4, 0H5), 7.03 (d, 4H, J ¼ 5.7 Hz, pyridyl), 6.91 (d, 4H,
0
J ¼ 7.5 Hz, H3 , H5 ), 3.37 (hepta, 4H, eCH(CH3)2), 1.02 (dd, 24H,
J ¼ 7.2 Hz, 7.2 Hz, eCH(CH3)2). Anal. Calcd for C48H52Cl2N4Pd2: C,
59.51; H, 5.41; N, 5.78. Found: C, 59.33; H, 5.49; N, 5.69.
Complexes 6e12 were prepared in a similar manner as complex
5.
zole) (3, 0.054 g, 60%). IR (KBr, cmꢀ1): 1602 ( C]N); 1H NMR
n
(300 MHz in CDCl3,
d
): 8.18 (d, 1H, J ¼ 8.4 Hz), 7.91 (s, 1H, eCH]N),
7.37 (d, 1H, J ¼ 7.5 Hz), 7.18e7.24 (m, 2H), 7.15 (br, 1H), 7.11 (d, 3H,
J ¼ 7.5 Hz), 6.49 (s, 1H), 6.15 (s, 1H), 3.40e3.55 (m, 5H, eCH(CH3)2,
NeCH3), 1.12 (d, 6H, J ¼ 6.9 Hz, eCH(CH3)2), 1.04 (d, J ¼ 6.6 Hz, 6H,
eCH(CH3)2). Anal. Calcd for C23H28ClN3Pd: C, 56.57; H, 5.78; N, 8.60.
Found: C, 56.79; H, 5.96; N, 8.55.
3.2.4. [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2}(Cl)]2(
m-bpy) (6, 63%)
IR (KBr, cmꢀ1): 1598 ( C]N); 1H NMR (300 MHz in CDCl3,
n
d):
8.27 (d, 4H, J ¼ 6.0 Hz, pyridyl), 7.83 (s, 2H, eCH]N), 7.70 (d, 2H,
0
J ¼ 2.1 Hz, H3), 7.32 (d, 2H, J ¼ 8.1 Hz, H6), 7.14e7.19 (m, 2H, H4 ), 7.09
0
0
Complex 4 was prepared in a similar manner as complex 3.
(m, 4H, J ¼ 5.7 Hz, pyridyl), 6.97 (d, 4H, J ¼ 7.8 Hz, H3 , H5 ), 6.67 (dd,
J ¼ 2.1, 2.1 Hz, 2H, H5), 3.93 (s, 6H, eOCH3), 3.40e3.53 (m, 4H,
eCH(CH3)2), 1.08 (dd, 24H, J ¼ 7.5 Hz, 7.5 Hz, eCH(CH3)2). Anal.
Calcd for C50H56Cl2N4O2Pd2: C, 58.38; H, 5.45; N, 5.39. Found: C,
58.65; H, 5.67; N, 5.41.
3.2.2. [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2}(L)(Cl)](L ¼ 1-
methylimidazole) (4, 45%)
IR (KBr, cmꢀ1): 1599 ( C]N); m.p.: 108e110 ꢁC; 1H NMR
n
(300 MHz in CDCl3,
d
): 7.78 (s, 1H, eCH]N), 7.76 (d, 1H, J ¼ 2.7 Hz,
0
imidazole), 7.29 (d, 1H, J0¼ 8.4 Hz, H6), 7.22 (d, 1H, J ¼ 8.1 Hz, H4 ),
3.2.5. [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(Cl)]2(m-bpe) (7, 65%)
0
7.08 (d, 2H, J ¼ 7.5 Hz, H3 , H5 ), 7.01 (s, 1H, imidazole), 6.63 (dd, 1H,
J ¼ 2.4, 2.4 Hz, imidazole), 6.48 (s, 1H, H5), 6.18 (s, 1H, H3), 3.92 (s,
3H, eOCH3), 3.40e3.56 (m, 5H, eCH(CH3)2, NeCH3), 1.10 (d, 6H,
J ¼ 6.9 Hz, eCH(CH3)2), 1.03 (d, 6H, J ¼ 6.9 Hz, eCH(CH3)2). Anal.
Calcd for C24H30ClN3OPd$CH2Cl2: C, 49.77; H, 5.35; N, 6.96. Found:
C, 50.03; H, 5.29; N, 6.80.
IR (KBr, cmꢀ1): 1600 ( C]N); 1H NMR (300 MHz in CDCl3,
n d):
8.12e8.19 (m, 6H, pyridyl, H3), 7.96 (s, 2H, eCH]N), 7.39 (d, 2H,
0
J ¼ 7.5 Hz, H6), 7.23e7.29 (m, 2H, H4 ), 7.18 (d, 1H, J ¼ 7.2 Hz, H4), 7.14
(d, 4H, J ¼ 8.4 Hz, eCH]CHe,0 H5), 7.04 (d, 4H, J ¼ 6.6 Hz, pyridyl),
0
7.00 (d, 4H, J ¼ 7.8 Hz, H3 , H5 ), 3.45 (hepta, 4H, eCH(CH3)2), 1.09
(dd, 24H, J ¼ 6.3 Hz, 5.4 Hz, eCH(CH3)2). Anal. Calcd for
C50H54Cl2N4Pd2: C, 60.37; H, 5.47; N, 5.63. Found: C, 60.25; H, 5.43;
N, 5.61.
3.2.6. [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2}(Cl)]2(
m
-bpe) (8, 83%)
IR (KBr, cmꢀ1): 1599 ( C]N); 1H NMR (300 MHz in CDCl3,
n
d): 8.14
(d, 4H, J ¼ 6.0 Hz, pyridyl), 7.82 (s, 2H, eCH]N), 7.72 (d, 2H,
J ¼ 2.4 Hz, H3), 7.31 (d, 2H, J ¼ 8.4 Hz, H6), 7.10e7.19 (m, 4H, eCH]
0
0
CHe, H4 ), 7.04 (d, 4H, J ¼ 6.0 Hz, pyridyl), 6.98 (d, 4H, J ¼ 7.5 Hz, H3 ,
0
H5 ), 6.67 (dd, J ¼ 2.4, 2.4 Hz, 2H, H5), 3.93 (s, 6H, eOCH3), 3.47
(hepta, 4H, eCH(CH3)2), 1.09 (dd, 24H, J ¼ 6.0 Hz, 5.7 Hz,
eCH(CH3)2). Anal. Calcd for C52H58Cl2N4O2Pd2$0.5C6H14: C, 60.17;
H, 5.97; N, 5.10. Found: C, 60.03; H, 5.70; N, 5.32.
3.2.7. [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(Cl)]2(m-bpt) (9, 58%)
IR (KBr, cmꢀ1): 1600 ( C]N); 1H NMR (300 MHz in CDCl3,
n d):
8.33 (d, 4H, J ¼ 6.3 Hz, pyridyl), 8.13 (d, 2H, J ¼ 7.5 Hz, H3), 7.99 (s,
2H, eCH]N), 7.59 (d, 4H, 0J ¼ 6.3 Hz, pyridyl), 7.42 (d,02H, J ¼ 7.5 Hz,
0
H6), 7.23e7.28 (m, 2H, H4 ), 7.18 (d, 4H, J ¼ 7.5 Hz, H3 , H5 ), 7.01 (d,
4H, J ¼ 7.8 Hz, H5), 3.45 (hepta, 4H, eCH(CH3)2), 1.10 (dd, 24H,
J ¼ 3.0 Hz, eCH(CH3)2). Anal. Calcd for C50H52Cl2N6Pd2S: C, 57.04; H,
4.98; N, 7.98; S, 3.05. Found: C, 56.72; H, 5.08; N, 7.76; S, 3.27. ESI-
MS: m/z ¼ 1018.5 (MHþ ꢀ Cl). C50H52ClN6Pd2S (Mr ¼ 1017.3).
3.2.8. [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2}(Cl)]2(m-bpt) (10,
65%)
IR (KBr, cmꢀ1): 1598 ( C]N); 1H NMR (300 MHz in CDCl3,
n d):
ꢁ
ꢀ
Fig. 3. Molecular structure of 13. Selected bond lengths (A) and angles ( ): Pd1eN1
2.025(6), Pd1eC15 1.964(7), Pd1eN3 2.022(7), Pd1eO1 2.194(5), N2eO3 1.242(9),
N2eO2 1.250(8), N2eO1 1.247(8); N1ePd1eN3 173.4(2), N1ePd1eC15 81.7(2),
N1ePd1eO1 92.5(2), C15ePd1eO1 169.7(3), Pd1eO1eN2 117.3(5), Pd1eN3eC20
166.3(7).
8.34 (d, 4H, J ¼ 6.3 Hz, pyridyl), 7.84 (s, 2H, eCCH]N), 7.71 (d, 2H,
J ¼ 2.1 Hz, H3), 7.58 (d, 4H, J ¼ 6.6 Hz, pyridyl), 7.33 (d, 2H, J ¼ 8.4 Hz,
0
0
0
H6), 7.11e7.19 (m, 2H, H4 ), 6.99 (d, 4H, J ¼ 7.5 Hz, H3 , H5 ), 6.68 (dd,
2H, J ¼ 2.4 Hz, 2.7 Hz, H5), 3.93 (s, 6H, eOCH3), 3.47 (hepta, 4H,

140
X. Chang et al. / Journal of Organometallic Chemistry 713 (2012) 134e142
ꢁ
ꢀ
Fig. 4. Molecular structure of 21. Selected bond lengths (A) and angles( ): Pd1eN6 2.030(3), Pd1eN4 2.037(3), Pd1eO1 2.154(2), Pd1eC27 1.977(3), Pd2eN9 2.030(3), Pd2eN7
2.037(3), Pd2eO5 2.146(2), Pd2eC52 1.978(4), Pd3eN10 2.032(3), Pd3eN12 2.041(3), Pd3eO10 2.143(3), Pd3eC77 1.992(3); N6ePd1eN4 177.22(11), C27ePd1eN6 81.71(12),
C27ePd1eO1 177.41(12), C27ePd1eN4 95.63(12), N4ePd1eO1 85.85(10), N9ePd2eN7 176.54(12), C52ePd2eN9 82.79(16), C52ePd2-O5 178.53(14), C52ePd2eN7 93.77(15),
N7ePd2eO5 87.32(11), N10ePd3eN12 174.14(11), C77ePd3eN12 81.65(13), C77ePd3eO10 174.04(13), N10ePd3eO10 91.62(11).
eCH(CH3)2), 1.09e1.12 (m, 24H, eCH(CH3)2). Anal. Calcd for
C52H56Cl2N6O2Pd2S: C, 56.12; H, 5.07; N, 7.55; S, 2.88. Found: C,
55.97; H, 4.66; N, 7.58; S, 2.94.
C21H25N3O3Pd: C, 53.23; H, 5.32; N, 8.87. Found: C, 53.11; H, 5.50; N,
8.76.
3.2.12. [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(ONO2)]2(
m
-bpy) (14)
(0.092 g,
3.2.9. [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(Cl)]3(tpt) (11, 83%)
To
a
20 mL CH3CN solution of complex
1
IR (KBr, cmꢀ1): 1601 (
58.83; H, 5.13; N, 8.23. Found: C, 58.39; H, 4.84; N, 8.36. ESI-MS: m/
z ¼ 1491.2 (M ꢀ Cl). C75H78Cl2N9Pd3 (Mr ¼ 1492.3). 1H NMR was not
performed due to their poor solubility in common organic solvents.
n
C]N); Anal. Calcd for C75H78Cl3N9Pd3: C,
0.113 mmol) was added AgNO3 (0.039 g, 0.230 mmol). After
stirring for 10 h in dark at room temperature, insoluble materials
were filtered off. The solvents of the filtrate were fully removed
by evaporation. To the resulting pale yellow oil was 10 mL CH2Cl2
and 4,40Bipyridyl (0.026 g, 0.135 mmol). After stirring for 14 h at
room temperature, the solvent was removed completely. The
resulting residue was washed with ether to give a pale yellow
solid. Recrystallization from CH2Cl2/hexane gave pale yellow
3.2.10. [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2}(Cl)]3(tpt) (12, 75%)
IR (KBr, cmꢀ1): 1598 ( C]N); m.p.: 280e282 ꢁC; 1H NMR
n
(300 MHz in CDCl3,
d
): 8.48 (d, 4H, J ¼ 5.7 Hz, pyridyl), 8.18 (dd, 4H,
J ¼ 6.0, 6.0 Hz, pyridyl), 7.87 (s, 2H, eCH]N), 7.74 (d, 2H, J ¼ 2.1 Hz,
needles of [Pd2(C6H4CH]NC6H3-2,6-i-Pr2)2(
0.082 g, 71%). IR (KBr, cmꢀ1): 1603 ( C]N), 1384 (nNO); 1H NMR
(300 MHz in CDCl3,
m-bpy)(ONO2)2] (14,
0
H3), 7.35 (d, 2H, J ¼ 8.1 Hz, H6), 7.15 (dd, 2H, J ¼ 7.5, 7.5 Hz, H4 ), 7.02
n
0
0
(d, 4H, J ¼ 7.8 Hz, H3 , H5 ), 6.69 (d, 2H, J ¼ 8.4 Hz, H5), 3.95 (s, 3H,
OCH3), 3.54 (hepta, 4H, eCH(CH3)2), 1.14 (dd, 24H, J ¼ 3.0, 3.0 Hz,
eCH(CH3)2). Anal. Calcd for C78H84Cl3N9O3Pd3: C, 57.79; H, 5.22; N,
7.78. Found: C, 57.93; H, 5.14; N, 8.08.
d
): 9.12 (d, 4H, J ¼ 6.3 Hz, pyridyl), 7.89 (s,
2H, eCH]N), 7.69 (d, 4H, J ¼ 6.6 Hz, pyridyl), 7.45 (d, 2H,
0
J ¼0 7.5 Hz, H6), 7.29e7.35 (m, 2H, H4 ), 7.20 (dd, 6H, J ¼ 8.4, 8.4 Hz,
0
H3 , H5 , H4), 7.10 (dd, 2H, J ¼ 7.8, 7.5 Hz, H5), 6.40 (d, 2H,
J ¼ 7.8 Hz, H3), 3.53 (hepta, 4H, eCH(CH3)2), 1.44 (d, 12H,
J ¼ 6.6 Hz, eCH(CH3)2), 1.18 (d, 12H, J ¼ 6.9 Hz, eCH(CH3)2). Anal.
Calcd for C48H52N6O6Pd2: C, 56.42; H, 5.13; N, 8.22. Found: C,
56.09; H, 5.08; N, 8.14.
3.2.11. [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(NCCH3)(ONO2)] (13)
To a 20 mL CH3CN solution of complex 1 (0.200 g, 0.246 mmol)
was added AgNO3 (0.093 g, 0.547 mmol). After stirring for 10 h in
dark at room temperature, insoluble materials were filtered off. The
solvents of the filtrate were fully removed by evaporation. The
resulting residue was solidified with hexane to give crude solids.
Recrystallization from CH2Cl2/hexane gave pale yellow crystals of
[Pd(C6H4CH]NC6H3-2,6-i-Pr2)(NCCH3)(ONO2)] (13, 0.161 g, 69%).
Complexes 15e19 were prepared in a similar way as complex 14.
3.2.13. [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2}(ONO2)]2(
m-bpy)
(15, 80%)
IR (KBr, cmꢀ1): 1599 ( C]N), 1384 (nNO); 1H NMR (300 MHz in
n
IR (KBr, cmꢀ1): 1601 (
(300 MHz in CDCl3,
(m, 1H), 7.24e7.30 (m, 1H), 7.15e7.18 (m, 5H), 3.43 (hepta, 2H,
eCH(CH3)2), 1.85 (br, 3H, CH3CN), 1.36 (dd, 6H, J ¼ 1.5, 2.4 Hz,
eCH(CH3)2), 1.14 (d, 6H, J ¼ 6.6 Hz, eCH(CH3)2). Anal. Calcd for
n
C]N), 1384 (nNO); m.p.: 114e116 ꢁC; 1H NMR
CDCl3,
d
): 9.07 (d, 4H, J ¼ 5.7 Hz, pyridyl), 7.75 (s, 2H, eCH]N), 7.64
d
): 7.76 (d, 1H, J ¼ 2.1 Hz, eCH]N), 7.33e7.37
(d, 4H, J ¼ 5.4 Hz, pyridyl), 7.39 (d, 2H,0 J ¼ 8.1 Hz, H6), 7.30 (d, 2H,
0
0
J ¼ 7.5 Hz, H4 ), 7.19 (d, 4H, J ¼ 7.5 Hz, H3 , H5 ), 6.66 (d, 2H, J ¼ 8.1 Hz,
H5), 5.87 (s, 2H, H3), 3.71 (s, 6H, eOCH3), 3.54 (hepta, 4H,
eCH(CH3)2), 1.43 (d, 12H, J ¼ 6.6 Hz, eCH(CH3)2), 1.18 (d, 12H,

X. Chang et al. / Journal of Organometallic Chemistry 713 (2012) 134e142
141
J ¼ 6.6 Hz, eCH(CH3)2). Anal. Calcd for C50H56N6O8Pd2: C, 55.51; H,
Complex 21 was prepared in a similar way as complex 20.
5.22; N, 7.77. Found: C, 55.12; H, 5.64; N, 7.45.
3.2.19. [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2}(ONO2)]3(tpt) (21,
3.2.14. [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(ONO2)]2(
m
-bpe) (16, 75%)
71%)
IR (KBr, cmꢀ1): 1603 (
n
C]N), 1384 (nNO); 1H NMR (300 MHz in
IR (KBr, cmꢀ1): 1600 ( C]N), 1384 (nNO); 1H NMR (300 MHz in
n
[d6]-DMSO,
d
): 9.01 (br, 4H, pyridyl), 8.52 (s, 2H, eCH]N), 7.93 (br,
CDCl3,
d
): 9.28 (d, 6H, J ¼ 5.4 Hz, pyridyl), 8.57 (d, 6H, J ¼ 5.7 Hz,
4H, pyridyl), 7.85 (br, 20H, eCH]CHe), 7.61 (d, 2H, J ¼ 7.2 Hz, H6),
pyridyl), 7.77 (s, 3H, eCH]N), 7.40 (d, 3H, J ¼ 8.1 Hz, H6), 7.30 (dd,
0
0
0
0
0
7.41 (t, 2H, J ¼ 7.2 Hz, H4 ), 7.33 (d, 4H, J ¼ 7.2 Hz, H3 , H5 ), 7.23 (t, 2H,
J ¼ 7.2 Hz, H5), 7.15 (dd, 2H, J ¼ 8.1, 7.8 Hz, H4), 6.28 (br, 2H, H3), 3.42
(m, 4H, eCH(CH3)2), 1.39 (d, 12H, J ¼ 6.6 Hz, eCH(CH3)2), 1.18 (d,
3H, J ¼ 7.8, 7.8 Hz, H4 ), 7.19 (d, 6H, J ¼ 7.8 Hz, H3 , H5 ), 6.68 (d, 3H,
J ¼ 8.1 Hz, H5), 5.91 (s, 3H, H3), 3.69 (s, 9H, eOCH3), 3.57 (hepta, 6H,
eCH(CH3)2), 1.45 (d, 18H, J ¼ 6.6 Hz, eCH(CH3)2), 1.19 (d, 18H,
J ¼ 6.9 Hz, eCH(CH3)2). Anal. Calcd for C78H84N12O12Pd3$CH2Cl2: C,
53.13; H, 4.85; N, 9.41. Found: C, 53.29; H, 5.28; N, 9.28.
12H,
J ¼ 6.6 Hz,
eCH(CH3)2).
Anal.
Calcd
for
C50H54N6O6Pd2$0.75CH2Cl2: C, 54.84; H, 5.03; N, 7.56. Found: C,
54.92; H, 4.88; N, 7.49.
3.3. X-ray structure determination
3.2.15. [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2}(ONO2)]2(
m-bpe)
(17, 78%)
Suitablecrystals for X-rayanalysis of3, 9,13 and 21 wereobtained
by recrystallization from CH2Cl2/hexane. X-ray data of complexes 3,
9,13 and 21 were collected on a D-MAX 2200 VPC diffractometer. All
IR (KBr, cmꢀ1): 1600 ( C]N), 1384 (nNO); 1H NMR (300 MHz [d6]-
n
DMSO, d): 9.00 (br, 4H, pyridyl), 8.34 (s, 2H, eCH]N), 7.93 (br, 4H,
pyridyl), 7.86 (br, 2H, eCH]CHe), 7.58 (d, 2H, J ¼ 8.4 Hz, H6), 7.39
the determinations of unit cell and intensity data were performed
0
0
0
(dd, 2H, J ¼ 8.4, 6.9 Hz, H4 ), 7.31 (d, 4H, J ¼ 7.5 Hz, H3 , H5 ), 6.80 (d,
2H, J ¼ 8.4 Hz, H5), 5.67 (br, 2H, H3), 3.68 (s, 6H, eOCH3), 3.45 (m,
4H, eCH(CH3)2), 1.37 (d, 12H, J ¼ 6.6 Hz, eCH(CH3)2), 1.17 (d, 12H,
J ¼ 6.6 Hz, eCH(CH3)2). Anal. Calcd for C52H58N6O8Pd2$0.5CH2Cl2:
C, 54.81; H, 5.17; N, 7.31. Found: C, 54.73; H, 4.98; N, 7.04.
ꢀ
with graphite-monochromated Mo K
a
radiation (
l
¼ 0.71073 A).
The data of complexes 3 and 13 were collected at room temperature
while the data of complex 9 and 21 were collected at 113 K using the
u
-scan technique. Details of the data collection and refinement are
summarized in Table 1. All calculations were carried out with the
SHELX-97 programs [44]. All structures were solved by direct
methods. All non-hydrogen atoms were refined with anisotropic
thermal parameters by using full-matrix least-squares methods.
3.2.16. [Pd(C6H4CH]NC6H3-2,6-i-Pr2)(ONO2)]2(
m-bpt) (18, 79%)
IR (KBr, cmꢀ1): 1602 ( C]N), 1384 (nNO); 1H NMR (300 MHz in
n
CDCl3,
d
): 9.17 (d, 4H, J ¼ 6.3 Hz, pyridyl), 8.09 (d, 4H, J ¼ 6.3 Hz,
pyridyl), 7.88 (s, 2H, eCH]N), 7.45 (d, 2H, J0¼ 7.2 Hz, H6), 7.31 (dd,
Acknowledgment
0
0
2H, J ¼ 7.2, 7.2 Hz, H4 ), 7.17e7.22 (m, 6H, H3 , H5 , H5), 7.09 (dd, 2H,
J ¼ 7.5, 7.5 Hz, H4), 6.39 (d, 2H, J ¼ 7.5 Hz, H3), 3.52 (hepta, 4H,
eCH(CH3)2), 1.44 (d, 12H, J ¼ 6.6 Hz, eCH(CH3)2), 1.18 (d, 12H,
This work was supported by the Project Sponsored by the
Scientific Research Foundation for the Returned Overseas Chinese
Scholars of State Education Ministry (2008), the Scientific Research
Foundation funded by Liaoning Provincial Education Department of
China [No. 2008T073], the Natural Science Foundation of Liaoning
Province [No. 201102085], and Foundation of 211 Project for
Innovative Talents Training, Liaoning University.
J ¼ 6.9 Hz,
eCH(CH3)2).
Anal.
Calcd
for
C50H52N8O6Pd2S$0.25CH2Cl2: C, 53.55; H, 4.69; N, 9.94; S, 2.84.
Found: C, 53.58; H, 4.81; N, 10.03, S, 3.03. ESI-MS: m/z ¼ 1106.5
(MHþ). C50H52N8O6Pd2S (Mr ¼ 1105.9).
3.2.17. [Pd{(4-MeO)C6H3CH]NC6H3-2,6-i-Pr2}(ONO2)]2(
m-bpt)
(19, 56%)
Appendix A. Supporting material
IR (KBr, cmꢀ1): 1599 ( C]N), 1384 (nNO); 1H NMR (300 MHz in
n
[d6]-DMSO, d): 9.13 (br, 4H, pyridyl), 8.35 (s, 2H, eCH]N), 8.28 (br,
CCDC 842514e842517 contains the supplementary crystallo-
graphic data for 3, 9, 13 and 21. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/deposit.
4H, pyridyl), 7.58 (d, 2H, J ¼ 8.4 Hz, H6), 7.40 (dd, 2H, J ¼ 7.8, 7.2 Hz,
0
0
0
H4 ), 7.32 (d, 4H, J ¼ 7.2 Hz, H3 , H5 ), 6.82 (d, 2H, J ¼ 8.4 Hz, H5), 5.76
(s, 2H, H3), 3.72 (s, 6H, eOCH3), 3.46 (hepta, 4H, eCH(CH3)2), 1.37 (d,
12H, J ¼ 6.3 Hz, eCH(CH3)2), 1.16 (d, 12H, J ¼ 6.6 Hz, eCH(CH3)2).
Anal. Calcd for C52H56N8O8Pd2S$0.5CH2Cl2: C, 52.18; H, 4.75; N,
9.27. Found: C, 51.88; H, 4.66; N, 7.04.
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To
a 15 mL CH2Cl2 suspension of complex 11 (0.103 g,
0.067 mmol) was added AgNO3 (0.044 g, 0.259 mmol) solution
dissolved in 5 mL methanol. After stirring for 10 h in dark at room
temperature, insoluble materials were filtered off, the filtrate was
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40
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0
0
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}