Synthesis and characterization of pyrrole-imine [N-NP] nickel(II) and palladium(II) complexes and their applications to norbornene polymerization

Article abstract of DOI:10.1021/om701297k

Ni(II) and Pd(II) complexes based on N-((1H-pyrrol-2-yl)methylene)-2- (diphenylphosphino)benzenamine were synthesized and characterized. X-ray diffraction studies on complexes 1, 2, and 4 revealed that N, N, P, and halogen atoms coordinated to metal, with

Full text of DOI:10.1021/om701297k

1924
Organometallics 2008, 27, 1924–1928
Synthesis and Characterization of Pyrrole-imine [N-NP] Nickel(II)
and Palladium(II) Complexes and Their Applications to Norbornene
Polymerization
Fu-Bin Han,† Yu-Liang Zhang, Xiu-Li Sun,* Bao-Guo Li,† Yang-Hui Guo, and
Yong Tang*
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese
Academy of Sciences, 354 Fenglin Lu, Shanghai, 200032, China
ReceiVed December 29, 2007
Ni(II) and Pd(II) complexes based on N-((1H-pyrrol-2-yl)methylene)-2-(diphenylphosphino)benzenamine
were synthesized and characterized. X-ray diffraction studies on complexes 1, 2, and 4 revealed that N,
N, P, and halogen atoms coordinated to metal, with distorted square planar geometries in all cases. Upon
treatment with modified methylaluminoxane (MMAO), the [N-NP]Ni(II)X complexes are robust and exhibit
high activity for the vinyl addition polymerization of norbornene (up to 5.46 × 107 g PNB/mol(Ni) · h · atm).
affording vinyl-addition polymers with molecular weights higher
than 106 g/mol.4 Of the Ni(II) and Pd(II) precatalysts developed,2–5
most are involved in bidentate ligand-derived complexes. A few
complexes based on tridentate ligands were reported for this
purpose except limited examples related to oligomerization of
ethylene.4a,g,n,5 Of them, Braunstein et al. described that a [NPN]
nickel complex could be used to promote oligomerization of
ethylene with a TOF up to 37 900 in the presence of 6 equiv of
AlEtCl2.5a Carpentier and Casagrande et al. documented that
tridentate pyrazolyl nickel complexes were highly efficient
catalysts for the dimerization of ethylene with a selectivity up
to 92% for the 1-butene fraction.5b Several 2,6-bis(imino)py-
ridine nickel complexes were synthesized.5c,d These nickel
complexes either proved to be inert to ethylene polymerization
or showed low activity (5 × 103 g/mol(Ni) · h · atm) for the
dimerization of ethylene. As our ongoing research project on
synthesis and applications of metal complexes based on triden-
tate ligands in asymmetric synthesis6 and olefin
polymerization,7very recently, we designed and synthesized
N-((1H-pyrrol-2-yl)-
Introduction
During the last decades, there have been tremendous advances
in the field of homogeneous late-transition metal catalysts for
olefin polymerization.1 For example, the families of nickel and
palladium complexes,2–4 such as those based on R-diimine2a or
salicylaldimine,2b,2c have proven to be one of the most efficient
precatalysts. In the presence of MMAO, R-diimine nickel and
palladium complexes could catalyze the polymerization of
ethylene or propylene with high activities to give linear to highly
branched or even to dendritic polymers.2a,e,3c,d Palladium
complexes could promote the copolymerization of ethylene with
polar comonomers such as methyl acrylate effectively.2d,f,g,3a,b,e,f
Salicylaldiminato nickel(II) complexes were reported to poly-
merize ethylene in the presence of functional additives.2c
Recently, some nickel and palladium complexes were also found
to be highly active for the polymerization of norbornene,
* To whom correspondence should be addressed. E-mail: xlsun@
mail.sioc.ac.cn or tangy@mail.sioc.ac.cn.
† College of Chemistry and Chemical Engineering, Inner Mongolia
University, Huhhot, 010021, Inner Mongolia, China.
methylene)-2-(diphenylphosphino)benzenamine (L1) and the cor-
(1) For recent reviews, see: (a) Britovsek, G. J. P.; Gibson, V. C.; Wass,
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10.1021/om701297k CCC: $40.75
2008 American Chemical Society
Publication on Web 03/21/2008

Pyrrole-imine Ni(II) and Pd(II) Complexes
Scheme 1. Synthesis of Complexes 1-4
Organometallics, Vol. 27, No. 8, 2008 1925
responding nickel-palladium complexes. It was found that the
nickel complexes could catalyze the polymerization of nor-
bornene with activity up to 5.46 × 107 g PNB/mol(Ni) · h · atm
in the presence of MMAO. In this paper, we wish to report the
results in detail.
Results and Discussion
Ligand and Complex Synthesis. Complexes 1-4 were
synthesized as shown in Scheme 1. Pyrrole-imine ligand L1
was prepared readily by the condensation of 2-(diphenylphos-
phino)aniline and pyrrole-2-carboxaldehyde in the presence of
silica–alumina 135 and 4 Å molecular sieves.8 Treatment of
pyrrole-imine ligand L1 with anhydrous NiX2 or PdCl2 in
anhydrous ethanol under reflux afforded the desired complexes
in 41–80% yields. In the solid state, complexes 1, 2, and 4 are
stable in air. Iodide 3 should be kept in the dark to avoid its
decomposition.
Figure 1. Molecular structure of complex 1. Selected bond length
(Å) and angles (deg): Ni-N(1) ) 1.888 (5), Ni-N (2) ) 1.886
(3), Ni-P ) 2.1458 (2), Ni-Cl ) 2.1628 (1), N(1)-Ni-N(2) )
83.8 (2), N(1)-Ni-P ) 169.54 (2), N(2)-Ni-P ) 86.3 (2),
N(1)-Ni-Cl ) 95.73 (2), N(2)-Ni-Cl ) 176.9 (2), P-Ni-Cl
) 94.30 (8).
All the complexes were well characterized by FT-IR,
1
elemental analyses, H NMR, and mass spectral analysis. The
C)N vibration absorption in IR spectra of complexes 1-4
exhibited a characteristic shift from 1619 cm-1 (free ligand) to
1547–1552 cm-1 (complexes), suggesting that the nitrogen
atoms of the imine groups coordinate to metal. The molecular
structures of complexes 1, 2, and 4 were further confirmed by
single-crystal X-ray analyses (Figures 1-3). As shown in Figure
1, nickel complex 1 adopts a distorted square planar geometry
around nickel(II). The N(1), N(2), P, and Cl atoms are nearly
coplanar, with Cl and N(2) occupying the trans position
(Cl-Ni-N(2) angels of 176.9°, N(1)-Ni-P: 169.54°). The
bond length of P-Ni (2.1458(2) Å) is shorter than that of the
reported salicylaldiminato nickel(II) complex (P-Ni 2.172 Å).2b
Noticeably, the Ni-N(1) bond and Ni-N(2) bond lengths are
virtually identical (Ni-N(1) ) 1.888(5) Å and Ni-N(2) )
1.886(3) Å), together with the fact of the longer C(4)-N(1)
bond length in the pyrrole ring than the C(1)-N(1) bond
(C(4)-N(1) ) 1.363(7) Å vs C(1)-N(1) ) 1.328(7) Å),
suggesting electron delocalization in the N(1)-C(4)-C(5)-N(2)
system. This is different from that of the pyrrolidine-imine based
Figure 2. Molecular structure of complex 2. Selected bond length
(Å) and angles (deg): Ni-N(1) ) 1.884(9), Ni-N(2) ) 1.874(6),
Ni-P(1) ) 2.150(3), Ni-Br ) 2.2304(16), N(1)-Ni-N(2) )
82.4(4), N(1)-Ni-P ) 169.0(3), N(2)-Ni-P ) 87.3(3), N(1)-
Ni-Br ) 96.9(3), N(2)-Ni-Br ) 175.7(3), P-Ni-Br ) 93.65(8).
titanium complexes reported by Fujita,9 in which the length
of the Ti-N (in pyrrole) bond is much shorter than that of the
Ti-N bond (in the imine group) (2.033 and 2.185 Å, respec-
tively).
The molecular structure of complexes 2 and 4 (Figures 2 and
3) are similar to that of complex 1, both with a distorted square
planar geometory with N(1), N(2), P, Br(Cl), and the metal atom
being nearly coplanar. However, the bond lengths of C(1)-N(1)
and C(4)-N(1) in pyrrole, which are different in complex 1
(C(1)-N(1) ) 1.328 (7) Å vs C(4)-N(1) ) 1.363 (7) Å), are
(6) (a) Zhou, J.; Tang, Y. J. Am. Chem. Soc. 2002, 124, 9030. (b) Huang,
Z.-Z.; Kang, Y.-B.; Zhou, J.; Ye, M.-C.; Tang, Y. Org. Lett. 2004, 6, 1677.
(c) Zhou, J.; Tang, Y. Chem. Soc. ReV. 2005, 34, 664. (d) Ye, M.-C.; Zhou,
J.; Tang, Y. J. Org. Chem. 2006, 71, 3576. (e) Xu, Z.-H.; Zhu, S.-N.; Sun,
X.-L.; Tang, Y.; Dai, L.-X. Chem. Commun. 2007, 1960. (f) Kang, Y.-B.;
Sun, X.-L.; Tang, Y. Angew. Chem., Int. Ed. 2007, 46, 3918.
(7) (a) Hu, W.-Q.; Sun, X.-L.; Wang, C.; Gao, Y.; Tang, Y.; Shi, L.-P.;
Xia, W.; Sun, J.; Dai, H.-L.; Li, X.-Q.; Yao, X.-L.; Wang, X.-R.
Organometallics 2004, 23, 1684. (b) Wang, C.; Sun, X.-L.; Guo, Y.-H.;
Gao, Y.; Liu, B.; Ma, Z.; Xia, W.; Shi, L.-P.; Tang, Y. Macromol. Rapid
Commun. 2005, 26, 1609. (c) Wang, C.; Ma, Z.; Sun, X.-L.; Gao, Y.; Guo,
Y.-H.; Tang, Y.; Shi, L.-P. Organometallics 2006, 25, 3259. (d) Gao, M.;
Wang, C.; Sun, X.; Qian, C.; Ma, Z.; Bu, S.; Tang, Y.; Xie, Z. Macromol.
Rapid Commun. 2007, 28, 1511.
(8) Qian, C. T.; Gao, F. F.; Chen, Y. F.; Gao, L. J. Synlett 2003, 10,
1419.
(9) Yoshida, Y.; Matsui, S.; Takagi, Y.; Mitani, M.; Nitabaru, M.;
Nakano, T.; Tanaka, H.; Fujita, T. Chem. Lett. 2000, 1270.

1926 Organometallics, Vol. 27, No. 8, 2008
Han et al.
(around 1.8 × 106 g/mol) with very narrow molecular weight
distributions between 1.12 and 1.31 were observed, suggesting
that a single sitelike catalyst be formed.
Under the optimized conditions, the behavior of complexes
1-4 on norbornene polymerization were examined (Table 3).
As shown in Table 3, nickel complexes 1-3 were highly active,
and the anion of the complexes had a great effect on both
conversions and activities. Nickel chloride 1 proved to be the
most active (5.46 × 107 g PNB/mol(Ni) · h · atm, 91% conver-
sion, entry 1). The activities and conversions diminished when
both bromide 2 and iodide 3 were used instead of the chloride
(entries 1–3, Table 3). Despite the different activity, all PNB
produced by complexes 1-3 have high Mw (106 g/mol), very
1
narrow PDI (1.24–1.27), and high TGA (>453 °C). The H
NMR and 13C NMR analysis showed no signal of double bonds
in the polymers, indicating that the polymers were norbornene
adducts through vinyl-addition polymerization. Compared with
the high activities exhibited by nickel complexes 1-3, their
palladium analogue 4 was found nearly inert toward norbornene
polymerization (entry 4).
There are two possible pathways for this polymerization. One
is that the polymerization proceeds via a vinyl-addition and
another is via a cationic process. We found that complex 1,
after treating with AgOTf and AgBF4, respectively, could not
promote this polymerization at all in the absence of MMAO
(Scheme 2). These results suggested that the cationic process
is less possible, and we proposed this polymerization proceeded
via vinyl-addition.
Figure 3. Molecular structure of complex 4. Selected bond length
(Å) and angles (deg): Pd-N(1) ) 2.043(4), Pd-N(2) ) 2.007(3),
Pd-P ) 2.2094(1), Pd-Cl ) 2.2925(1), N(1)-Pd-N(2) ) 81.2(2),
N(1)-Pd-P ) 165.47(1), N(2)-Pd-P ) 84.58(2), N(1)-Pd-Cl
) 97.80(1), N(2)-Pd-Cl ) 177.3(2), P-Pd-Cl ) 96.57(6).
almost the same in complex 2 (C(1)-N(1) ) 1.388 (13) Å vs
C(4)-N(1) ) 1.392 (14) Å). Noticeably, the lengths of
Ni(Pd)-N(imine)bondsareshorterthanthoseofNi(Pd)-N(pyrrole)
bonds in all cases, and the difference is in the order of 1 (0.002
Å) < 2 (0.010 Å) < 4 (0.036 Å). Attempts to develop crystals
of complex 3 suitable for X-ray analysis failed.
Conclusions
Norbornene Polymerization. In the presence of MMAO,
nickel and palladium complexes 1-4 proved to be inactive to
catalyze the polymerization of ethylene either at 50 °C, 1 atm
or at 30 °C, 10 atm. However, complexes 1-3 could promote
the polymerization of norbornene (NB) very well. For example,
it was found that polynorbornene (PNB) generated immediately
after MMAO was added to a mixture of norbornene and nickel
complex in CH2Cl2 or ClCH2CH2Cl. Further study showed that
the polymerization conditions strongly influenced the activities.
As shown in Table 2, increasing the initial concentration of
norbornene resulted in an improvement of activity from 1.49 ×
107 g PNB/mol(Ni) · h · atm to 4.72 × 107 g PNB/mol(Ni) · h · atm
(entries 1–3). The activities decreased with the prolongation of
the polymerization time probably due to poor solubility of the
quickly formed polymer in dichloromethane (DCM), which
might block catalytic species (entries 2 and 4–6). Al/M molar
ratios were also influenced strongly by the polymerization
behaviors. For example, with the increase of the ratio from 100
to 2000, the activity was enhanced nearly four times (entries 2
and 7–9). Noticeably, high activity (1.1 × 107 g PNB/mol(Ni) ·
h · atm) was still observed in the presence of low Al/M molar
ratio (Al/M molar ratio: 100), indicating that the stability of
the active species was quite good. Solvents also strongly
influenced the activity probably due to the solubility of complex
1 in the solvents. For example, both PhCl and CHCl3 gave lower
activity than DCM, and only a trace amount of polymer was
observed in toluene (entries 2 and 15–17). 1,2-Dichloroethane
(1,2-DCE) proved to be the optimal one. Under similar
conditions in 1,2-DCE, 91% conversion of norbornene was
achieved, and the activity was improved to 5.46 × 107 g PNB/
mol(Ni) · h · atm. Control experiments showed that no polymers
were produced in the absence of MMAO or complex 1.
Molecular weights of the produced PNB were slightly influenced
by reaction conditions. In all cases determined, high Mw’s
Nickel(II) and palladium(II) complexes based on N-((1H-
pyrrol-2-yl)methylene)-2-(diphenylphosphino)benzenamine (L1)
have been synthesized and characterized. The X-ray diffraction
studies reveal that these complexes feature a distorted square
planar coordination of the central metal with the N, N, and P
atoms. In the presence of methylaluminoxane (MMAO), an
activity of up to 5.46 × 107 g PNB/mol(Ni) · h · atm has been
achieved with nickel complexes for the polymerization of
norbornene. Further investigations into the polymerization
mechanism are in progress in our laboratory.
Experimertal Section
General Information. All experiments involving air- and/or
moisture-sensitive compounds were carried out under an atmosphere
of dried and purified nitrogen using standard Schlenk techniques.
1H NMR, 13C NMR, and 31P NMR were recorded on a Varian
Mercury 300 spectrometer. Mass spectra were carried out with a
HP5989A spectrometer. IR spectra were recorded using a Nicolet
AV-360 spectrometer. Elemental analyses were performed by the
Analytical Laboratory of Shanghai Institute of Organic Chemistry
(CAS). High-temperature gel permeation chromatography (GPC)
was performed on Waters Alliance GPC 2000 in 1,2,4-trichlo-
robenzene at 135 °C using polystyrene calibration. Modified
methylaluminoxane (MMAO) was purchased from Akzo Nobel with
7 wt % Al (1.9 M) in toluene. Toluene was distilled under nitrogen
over sodium-benzophenone. Norbornene was refluxed over Na and
distilled. CH2Cl2 and ClCH2CH2Cl were dried over CaH2. Ethanol
was purified prior to use. 2-(Diphenylphosphino)aniline was
synthesized according to the literature methods.10
X-Ray Structure Determination. Data were collected at 293
K on a Bruker SMART 1000 CCD diffractometer using Mo K (λ
(10) Allock, H. R. Inorganic Syntheses; Wiely: New York, 1989;
Vol. 25.

Pyrrole-imine Ni(II) and Pd(II) Complexes
Organometallics, Vol. 27, No. 8, 2008 1927
Table 1. Crystal Data and Summary of Data Collection and Refinement Details for 1, 2, and 4
1
2
4
formula
crystal size (mm)
fw
C23H18N2ClPNi
0.36 × 0.23 × 0.04
447.52
C23H18BrN2NiP
0.32 × 0.13 × 0.06
491.98
C23H18N2PClPd
0.33 × 0.16 × 0.11
495.21
crystal system
space group
a, Å
Orthorhombic
Pna2(1)
Orthorhombic
Pna2(1)
Orthorhombic
Pna2(1)
18.7870(18)
8.8927(9)
11.8928(12)
1986.9(3)
4
1.496
4.34 to 56.52
1.202
18.8941(17)
8.8776(8)
11.9195(11)
1999.3(3)
4
1.634
4.32 to 51.98
3.060
18.8885(13)
8.9493(7)
11.9998(9)
2028.4(3)
4
1.622
4.32 to 56.56
1.136
b, Å
c, Å
V, Å3
Z
Dcalcd, Mg/m3
2θ range, deg
µ, mm-1
F(000)
920
992
992
reflections collected/unique
data/restraints/parameters
goodness of fit
R1 (I > 2σ(I))
wR2 (I > 2σ(I))
absolute structure parameter
11598/4420 [R(int) ) 0.0931]
4420/1/253
0.699
0.0507
0.0740
10491/3843 [R(int) ) 0.0824]
3843/1/254
1.069
0.0777
0.2321
11928/3614 [R(int) ) 0.0611]
3614/1/257
0.773
0.0362
0.0496
0.02(2)
0.00(5)
0.01(3)
Table 2. Polymerization of Norbornene with 1/MMAOa
entry
NB (g)
solvent
T (°C)
Al/cat
yield (g)
conv. (%)
activityb
Mw (106 g/mol)c
PDIc
1
2
1.0
2.0
3.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
1.0
1.0
1.0
1.0
2.0
2.0
2.0
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
30
30
30
30
30
30
30
30
30
30
0
30
50
70
30
30
30
500
500
500
500
500
500
100
1000
2000
500
500
500
500
500
500
500
500
0.495
1.092
1.574
0.975
1.250
1.379
0.353
1.327
1.368
1.820
0.453
0.637
0.656
0.610
0.385
trace
49.50
54.60
52.47
48.75
62.50
68.95
17.65
66.35
68.40
91.00
45.30
63.70
65.60
61.00
19.25
-
1.49
3.28
4.72
2.92
1.88
0.83
1.06
3.98
4.10
5.46
1.36
1.91
1.97
1.83
1.16
-
1.85
1.90
2.02
2.00
1.91
1.83
1.93
1.84
1.70
1.77
-
-
-
-
-
-
-
1.23
1.17
1.12
1.13
1.19
1.20
1.17
1.23
1.31
1.27
-
-
-
-
-
-
-
3
4d
5e
6f
7
8
9
DCM
10
11
12
13
14
15
16
17
1,2-DCE
1,2-DCE
1,2-DCE
1,2-DCE
1,2-DCE
PhCl
toluene
CHCl3
0.121
6.05
0.36
a Cat. 1 µmol; 2 min; Vtotal 25.0 mL. b 107 g of PNB/mol · h · atm. c Determined by GPC. d 1 min. e 4 min. f 10 min.
Table 3. Influence of Catalysts on the Activitiesa
Scheme 2. Control Experiments
Mw
entry cat. yield (g) conv. (%) activityb (106 g/mol)c PDIc TGA/°C
1
2
3
4
1
2
3
4
1.820
1.288
0.868
trace
91.00
64.40
43.40
-
5.46
3.86
2.60
-
1.770
1.778
1.822
-
1.27 453.47
1.27 453.81
1.24 454.49
-
-
a Cat., 1 µmol; Al/Cat. (mol), 500; NBE, 2.0 g; Vtotal, 25.00 mL; 30
°C; 2 min; 1,2-DCE. b 107 g of PNB/mol · h; c Determined by GPC.
) 0.71073 Å) radiation. An empirical absorption correction was
applied using the SADABS program.11 All structures were solved
by direct methods and subsequent Fourier difference techniques
and refined anisotropically for all nonhydrogen atoms by full-matrix
least-squares calculations on F2 using the SHELXTL program
package (PC version).12 All hydrogen atoms were geometrically
fixed using the riding model. Crystal data and details of data
collection and structure refinements were given in Table 1. Further
details were included in the Supporting Information.
18.7 mmol) was treated with 2-(diphenylphosphino)aniline (4.71
g, 17.0 mmol) in toluene (60 mL). The solution was heated to 80
°C and stirred for 26 h. Then the insoluble matters were eliminated
by celite filtration, and the filtrate was concentrated under reduced
pressure. The residue was purified by recrystallization from ethanol,
and the white crystals were collected. Yield: 4.81 g (80%). 1H NMR
(CDCl3/TMS, 300 MHz): δ ) 9.18 (brs, 1 H, NH), 8.00 (s, 1 H,
CH)N), 7.37–7.23 (m, 11 H), 7.10–7.01 (m, 2 H), 6.77–6.82 (m,
2 H), 6.49–6.51 (m, 1 H), 6.18–6.20 (m, 1 H). 13C NMR (75 MHz,
CDCl3): δ ) 153.8 (d, J ) 18.0 Hz), 148.5, 148.4, 137.1 (d, J )
10.0 Hz), 134.0 (d, J ) 20 Hz), 132.7, 132.6, 132.5, 130.8, 129.8,
128.4, 128.3, 128.2, 125.4, 122.9, 117.1, 117.0, 115.9, 110.1. 31P
NMR: –12.8. IR (KBr): νCdN 1619 cm-1. MS (EI, m/z): 44 (100),
354 (M+, 53), 183 (43), 277 (40), 353 (31), 261 (26), 41 (12), 199
(12). Anal. Calcd. for C23H19N2P: C, 77.95; H, 5.40; N, 7.90. Found:
C, 78.19; H, 5.58; N, 7.80.
Synthesis of Ligand L1. In the presence of silicon-aluminum
135 and 4 Å molecular sieves, pyrrole-2-carboxaldehyde (1.78 g,
(11) Sheldrick, G. M. SADABS: Program for Empirical Absorption
Correction Of Area Detector Data; University of Göttingen: Göttingen,
Germany, 1996.
(12) SHELXTL V 5.03 Program Package; Siemens Analytical X-ray
Instruments, Inc.: Madison, WI, 1995.

1928 Organometallics, Vol. 27, No. 8, 2008
Han et al.
7.20–7.27 (m, 1 H), 7.06–7.09 (m, 1 H), 6.40 –6.42 (m, 1 H). 31
NMR: 42.3. Anal. Calcd. for C23H18ClN2PdP: C, 55.78; H, 3.66;
N, 5.66. Found: C, 55.34; H, 3.48; N, 5.4. IR (KBr): νCdN 1547
cm-1. MS (EI, m/z): 494 (M+, 30), 183 (100), 496 (28), 275 (27),
459 (5), 353 (18). X-ray: Crystal suitable for X-ray analysis grows
from CH2Cl2-Hexane.
General Procedure for Polymerization of Norbornene. To a
solution of norbornene and precatalyst (1 µmol) in CH2Cl2 was
added MMAO (1.9 M in toluene) via a syringe. After the desired
time, the reaction mixture was quenched by adding acidified EtOH
(5 mL, EtOH/concentrated HCl, 10/1, v/v). The mixture was poured
into a solution of concentrated HCl in EtOH (5%, v/v) and stirred
for 12 h. The polymer was collected by filtration, washed with
EtOH, and dried under reduced pressure at 50 °C to constant weight.
Synthesis of Complex 1. To a mixture of anhydrous NiCl2 (0.726
g, 2.05 mmol) and ligand L1 (0.253 g, 1.95 mmol) was added
anhydrous ethanol (25 mL). The solution was stirred and refluxed for
18 h and then was cooled to room temperature. The dark-red precipitate
was collected, washed with anhydrous ethanol, dissolved in CH2Cl2,
and filtrated. The filtrate was concentrated under reduced pressure.
The residue was purified by recrystallization from CH2Cl2 to give
a dark-red solid. Yield: 0.546 g (63.0%). The other complexes 2-4
were synthesized via the same procedure.
P
1: 1H NMR (DMSO-d6, 300 MHz): δ ) 8.53 (s, 1 H), 7.82–7.89
(m, 5 H), 7.49–7.64 (m, 8 H), 7.20–7.26 (m, 1 H), 6.94 –6.97 (m,
2 H), 6.26–6.27 (m, 1 H). 31P NMR (CDCl3, 121 MHz): 27.6. Anal.
Calcd. for C23H18ClN2NiP: C, 61.37; H, 4.05; N, 6.26; Cl, 7.92.
Found: C, 61.79; H, 4.37; N, 6.60; Cl, 7.81. IR (KBr): νCdN 1552
cm-1. MS (EI, m/z): 447 ((M+1)+,18), 210 (100), 282 (29), 351
(15). X-ray: Crystal suitable for X-ray analysis grows from
CH2Cl2-pentane.
Typical IR spectra for the obtained PNB (KBr): 2946 (vs), 2867
(vs), 1474 (s), 1453 (s), 1375 (m), 1294 (m), 1257 (m), 1223 (m),
1146 (m), 1107 (m), 890 (m). 1H NMR (o-dichlorobenzene-d4, 300
MHz, 110 °C): δ 0.90–2.70 (m). 13C NMR (o-dichlorobenzene-d4,
75 MHz, 110 °C): δ 29.70–32.05 (m), δ 35.34–39.88 (m), δ
47.05–49.24 (m).
2: yield, 41.3%. 1H NMR (CDCl3/TMS, 300 MHz): δ )
7.85–7.92 (m, 5 H), 7.40–7.54 (m, 9 H), 7.26–7.30 (m, 1 H),
7.09–7.13 (m, 1 H), 6.97–7.00 (m, 1 H), 6.31–6.33 (m, 1 H). 31P
NMR: 32.5. Anal. Calcd. for C23H18BrN2NiP: C, 56.15; H, 3.69;
N, 5.69; Br, 16.24. Found: C, 55.51; H, 3.66; N, 4.96; Br, 16.34.
IR (KBr): νCdN 1552 cm-1. MS (EI, m/z): 490 (M+, 50), 57 (100),
97 (80), 492 (70), 411 (36), 349 (34). X-ray: Crystal suitable for
X-ray analysis grows from CH2Cl2.
Acknowledgment. We thank the financial support from the
Natural Sciences Foundation of China, the Major State Basic
Research Development Program (Grant No. 2006CB806105),
The Chinese Academy of Sciences, and The Science and
Technology Commission of Shanghai Municipality.
1
3: yield, 70.5%. H NMR (CDCl3/TMS, 300 MHz): δ 8.05 (d,
2.1 Hz, 1 H), 7.84–7.92 (m, 4 H), 7.70 (s, 1 H), 7.42–7.54 (m, 8
H), 7.19–7.27 (m, 1 H), 7.08–7.14 (m, 1 H), 7.00 –7.02 (m, 1 H),
6.28–6.31 (m, 1 H). 31P NMR: 41.8. Anal. Calcd. for C23H18IN2NiP:
C, 51.25; H, 3.37; N, 5.20; I, 23.55. Found: C, 50.88; H, 4.06; N,
4.58; I, 23.25. IR (KBr): νCdN 1551 cm-1. MS (EI, m/z): 538 (M+,
63), 411 (100), 413 (42), 183 (38), 540 (28), 539 (18).
Supporting Information Available: NMR spectra of LI,
complexes 1-4, and polymer as well as X-ray crystallographic data
in CIF format for 1, 2, and 4. This material is available free of
charge via the Internet at http://pubs.acs.org.
1
4: yield, 80.6%. H NMR (CDCl3/TMS, 300 MHz): 8.17 (s, 1
H, CH)N), δ ) 7.79–7.86 (m, 4 H), 7.39–7.64 (m, 10 H),
OM701297K