Novel nickel(II) and copper(II) complexes with phenoxy-imidazole ligands: Syntheses, crystal structures and norbornene addition polymerization

Article abstract of DOI:10.1016/j.jorganchem.2007.04.010

The novel nickel(II) (1) and copper(II) (2) complexes bearing 2′-(4′,6′-di-tert-butylhydroxy-phenyl)-1,4,5-triphenyl imidazole ligand have been synthesized and characterized. The molecular structure analyses of complexes 1 and 2 indicated that Ni(II) cent

Full text of DOI:10.1016/j.jorganchem.2007.04.010

Journal of Organometallic Chemistry 692 (2007) 3435–3442
www.elsevier.com/locate/jorganchem
Novel nickel(II) and copper(II) complexes with
phenoxy-imidazole ligands: Syntheses, crystal structures
and norbornene addition polymerization
*
Feng-Tai Chen, Guang-Rong Tang, Guo-Xin Jin
Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200433, PR China
Received 13 February 2007; received in revised form 3 April 2007; accepted 10 April 2007
Available online 14 April 2007
Abstract
The novel nickel(II) (1) and copper(II) (2) complexes bearing 20-(40,60-di-tert-butylhydroxy-phenyl)-1,4,5-triphenyl imidazole ligand
have been synthesized and characterized. The molecular structure analyses of complexes 1 and 2 indicated that Ni(II) centre in 1 adopts
a distorted tetrahedral coordination geometry with a dihedral angle of 85.2ꢀ between Ni(1)O(1)N(1) plane and Ni(1)O(1A)N(1A) plane,
while the Cu(II) centre in 2 represents a distorted square planar coordination geometry with a cis-N2O2 arrangement of the donor atoms,
the dihedral angle being 32ꢀ between Cu(1)O(1)N(1) plane and Cu(1)O(1A)N(1A) plane. After activation with methylaluminoxane
(MAO), both Ni(II) and Cu(II) complexes can be used as catalysts for the addition polymerization of norbornene (NB). The polynor-
bornenes (PNBs) are produced with very high polymerization activity (108 g PNB molꢀ1 Ni hꢀ1) for Ni(II) complex and moderate cat-
alytic activity (105 g PNB molꢀ1 Cu hꢀ1) for Cu(II) complex, respectively. The high molecular weight polynorbornenes (106) are obtained
for complexes 1 and 2. Moreover, the distinct effects of polymerization temperature and Al/M ratio on catalytic activities and molecular
weights of polymers are discussed.
ꢁ 2007 Elsevier B.V. All rights reserved.
Keywords: Nickel; Copper; Catalysts; Phenoxy-imidazole ligand; Polymerization; Norbornene
1. Introduction
lished in this field show the intense exploration and com-
mercialization of new polymerization technologies [3].
Polynorbornene (PNB) with different structures and
properties can be afforded via three corresponding path-
ways: ring-opening metathesis polymerization (ROMP),
cationic or free-radical polymerization, and addition poly-
merization (Scheme 1) [4]. The first type of polymers con-
tains double bonds in their backbone, which must be
further vulcanized or hydrogenated for commercialization.
Low molecular weight polymers are formed through 2,7-
linkage in the second type of polymerization products.
However, in the addition type polynorbornene, the bicyclic
structure remains intact and only the p-bond of the cyclo-
olefin is opened. This type of specialty polymers exhibits
interesting and unique properties like high chemical
resistance, high glass transition temperature, large refrac-
tive index, low dielectric constant, and excellent optical
Olefin polymerization of late transition metal catalysts
has attracted considerable attention in academic and indus-
trial fields over the past decade [1]. Extraordinary roles
have been played by nickel-based catalysts in oligomeriza-
tion or polymerization of olefin. Nickel catalysts are best
known to oligomerize ethylene, dimerize propylene and
higher a-olefins, in which there exists the competition
between olefin-insertion and chain-transfer processes [2].
Obviously, this is a function of a number of parameters,
containing the nature of the ligands and structure of the
precatalysts. A large number of papers and patents pub-
*
Corresponding author. Fax: +86 21 65643776.
E-mail address: gxjin@fudan.edu.cn (G.-X. Jin).
0022-328X/$ - see front matter ꢁ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.04.010

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F.-T. Chen et al. / Journal of Organometallic Chemistry 692 (2007) 3435–3442
lhydroxy-phenyl)-1,4,5-triphenyl imidazole (LH). The novel
nickel(II) and copper(II) complexes, bis{(20-(40,60-di-tert-
butylhydroxy-phenyl)-1,4,5-triphenyl imidazole)}nickel (NiL2)
(1) and bis{(20-(40,60-di-tert-butylhydroxy-phenyl)-1,4,5-tri-
phenyl imidazole)}copper (CuL2) (2), have been synthesized
and characterized. Preliminary results from the complexes
catalyzing norbornene polymerization after activation with
methylaluminoxane (MAO) are investigated. The ultrahigh
catalytic activity (108 g PNB molꢀ1 Ni hꢀ1) is observed for
addition polymerization of norbornene in the nickel(II)/
MAO system.
ROMP
n
7
1
2
6
cationic or radical
n
4
3
5
n
vinyl-type
3
2
7
1
4
2. Results and discussion
5
6
n
Scheme 1. Schematic representation of the three different types of
polymerization for norbornene.
2.1. Preparation of ligands and complexes
The syntheses of the nickel and copper complexes as cat-
alytic precursors are shown in Scheme 2. According to a
modified method [12], the phenol-imidazole ligand was effi-
ciently synthesized. Complex formation was achieved by
treatment of NiCl2 or CuBr2 with 2 equiv. of the lithium
salt of the phenol-imidazole ligand obtained by the reac-
transparency. Driving by industrial application, the addi-
tion polymerization of norbornene has inspired the interest
of chemists and chemical engineers [5].
In 2001, Janiak and Lassahn [4a] gave an overall review
on the vinyl addition polymerization of norbornene using
various metal complexes as catalysts, including early tran-
sition metals (zirconium and titanium) and late transition
metals (palladium and nickel). After Deming and Novak
[6] introduced the first nickel complex for the vinyl addition
polymerization of norbornene, several other catalyst sys-
tems have also been applied to this polymerization reaction
[7]. However, copper-based catalysts are considerably rare
for olefin polymerization in literatures reported [8],
although copper (II) catalysts possess some unique proper-
ties in both homo- and copolymerization of olefins with
function monomers [9]. In vinyl addition polymerization
of norbornene, only a few examples are reported so far [10].
In our research, considerable effort has been devoted to
design and synthesize novel olefin polymerization catalysts
bearing [N,O], [N,N], and [N,P] ligands. Good catalytic
activities have been exhibited by some catalysts in the poly-
merization of ethylene and norbornene [11]. In recent years,
[N,O] bidentate ligand has been one of our preferred
objects. Considering the bulky steric hinder and electronic
conjugative effect, in this contribution, we prepared a phe-
nol-imidazole [N,O] bidentate ligand, (20-(40,60-di-tert-buty-
n
tion of the ligand with BuLi. The attempts to obtain the
complexes by direct reaction of Ni(OAc)2 Æ 4H2O or Cu-
(OAc)2 Æ 2H2O with the phenol-imidazole ligand are not
particularly successful. Crystal suitable for X-ray crystal-
lography of complex 1 or 2 was obtained by slow diffusion
of hexane into the dichloromethane solution of complex 1
or 2.
The structures of complexes 1 and 2 are shown in Figs. 1
and 2, respectively. The crystallographic data and refine-
ment parameters of 1 and 2 are summarized in Table 3.
For nickel (1) and copper (2) complexes, each ligand acts
as an N,O-bidentate ligand and each metal possesses
four-coordinate N2O2-coordination sphere. The Ni(II) cen-
tre of complex 1 represents a distorted tetrahedral coordi-
nation geometry with a dihedral angle of 85.2ꢀ between
Ni(1)O(1)N(1) plane and Ni(1)O(1A)N(1A) plane, while
the Cu(II) centre of complex 2 possesses a distorted square
planar coordination geometry with a cis-N2O2 arrangement
of the donor atoms, the dihedral angle being 32ꢀ between
Cu(1)O(1)N(1) plane and Cu(1)O(1A)N(1A) plane. It is
noticeable that the coordinate geometry of the metal Ni(II)
obviously deviates from the preferred square planar struc-
N
tBuLi
2
OH
N
O
O
N
1)
2
M
N
2) NiCl2 or CuBr2
N
N
M=Ni(1),Cu(2)
Scheme 2. Synthesis of nickel (1) and copper (2) complexes.

F.-T. Chen et al. / Journal of Organometallic Chemistry 692 (2007) 3435–3442
3437
Fig. 1. (a) ORTEP drawing of complex 1. The hydrogen atoms and solvent molecules are omitted for clarity. (b) Molecular packing diagram of 1. Selected
˚
bond lengths (A) and angles (ꢀ): Ni(1)–O(1) 1.884(3); Ni(1)–N(1) 1.971(2); O(1)–Ni(1)–N(1) 92.64(8); O(1)–Ni(1)–O(1A) 118.18(13); O(1A)–Ni(1)–N(1)
121.31(9); N(1)–Ni(1)–N(1A) 113.17(12).
Fig. 2. (a) The molecular structure of complex 2. (b) Molecular packing diagram of 2. The hydrogen atoms and solvent molecules are omitted for clarity.
˚
Selected bond lengths (A) and angles (ꢀ): Cu(1)–O(1) 1.891(2); Cu(1)–N(1) 1.945(2); O(1)–Cu(1)–N(1) 88.12(10); O(1A)–Cu(1)–O(1) 93.84(13); O(1)–
Cu(1)–N(1A)157.78(9); N(1A)–Cu(1)–N(1) 98.37(15).
ture and takes distorted tetrahedral coordination geometry
because of the steric hindrance of the butyl of phenol and a
phenyl group of imidazole ring.[13] The Ni(1)–O and
The X-ray analysis shows that there exist two intramo-
lecular p–p interactions between the phenyl ring at 4-posi-
tion (C9) of imidazole of one ligand and the phenol and/or
imidazole ring of the other ligand in the molecular struc-
tures of both 1 and 2 (see Fig. 3) [16]. For complex 2, the
weak intermolecular H–p interactions are formed between
the hydrogen of a phenyl ring at 1-position (N2) of imidaz-
ole in one molecule and a phenol ring in the other mole-
cule. The distance between hydrogen atom and the center
˚
Ni(1)–N distances are 1.884(3) and 1.971(2) A, respectively,
˚
which are longer than those (1.828(6) and 1.908(7) A,
respectively) found in the bis[(N-2,6-diisopropylphenyl)sal-
icylaldiminate]nickel(II) complex [14]. The lengths of
˚
Cu(1)–O and Cu(1)–N (1.891(2) and 1.945(2) A, respec-
tively) are similar to those of bis(salicylaldiminate)cop-
per(II) complex [15].
˚
of phenol ring is 3.18 A (Fig. 3). The zigzag stacking

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F.-T. Chen et al. / Journal of Organometallic Chemistry 692 (2007) 3435–3442
Fig. 3. View of complex 2 showing the intramolecular p–p interactions between the two ligands of the same molecular and intermolecular H–p
interactions between hydrogen atom of one molecule and a phenol ring the other molecule.
manner along c-axis for 1 and a-axis for 2 direction can
also be observed (Figs. 1 and 2).
Table 2
Norbornene polymerization for the 2/MAO catalytic systema
Run
Al/Cu
t (ꢀC)
Yield (g)
Activityb
Mvc
3. Norbornene polymerization
1
2
3
4
5
6
7
8
9
500
1000
1500
2000
2500
3000
2000
2000
2000
2000
60
60
60
60
60
60
30
45
75
90
0.063
0.494
0.578
1.582
0.106
0.018
Trace
0.022
0.080
0.058
12.2
98.7
115.6
316.3
21.1
3.5
–
4.4
16.0
11.5
1.83
1.96
2.22
1.92
1.76
1.46
–
1.79
1.98
2.05
The polymerization results catalyzed by complexes 1
and 2 in the presence of MAO are summarized in Tables
1 and 2. No catalytic activity was observed for complexes
1 and 2 in the absence of MAO. Therefore, the cocatalyst
MAO, which can create an empty site for coordination
and insertion of the norbornene, is essential for the nor-
bornene polymerization catalyzed by complexes 1 and 2
[17]. After activation with MAO, both Ni(II) and Cu(II)
complexes can catalyze norbornene (NB) polymerization.
Variation of the ratio of [Al]/1 or 2, which is expressed
here as the Al/Ni or Al/Cu ratio, shows a significant effect
on the catalytic activities and molecular weight. For Ni(II)
complex 1, the catalytic activities are very high up to
10
a
Polymerization conditions: [Cu] = 5 lmol, [NB] = 1.88 g; time = 1 h;
Vtotal = 15.0 mL; solvent: chlorobenzene.
b
103 g PNB molꢀ1 Cu hꢀ1
106 g molꢀ1
.
c
.
108 g PNB molꢀ1 Ni hꢀ1. The activities increase with the
increase of the Al/Ni ratio under the experimental condi-
tions. When the ratio of Al/Ni was 10,000/1, the highest
activity of 2.29 · 108 g PNB molꢀ1 Ni hꢀ1 (Table 1, Run
6) is observed. The catalytic polymerization behavior of
Cu(II) complex 2 is different from that of Ni(II) complex
1. The catalytic activities of 2 increases first and then sharply
decrease. The highest activity of 3.16 · 105 g PNB molꢀ1
Cu hꢀ1 is observed at Al/Cu ratio of 2000/1 (Table 3, Run
4). All polymers display high molecular weights (Mv up to
106). The effect of Al/M ratio on molecular weight of poly-
mers is different. For complex 1, Mv varies irregularly with
the increase of Al/Ni ratio, but Mv increases first and then
decreases with the increase of Al/Cu ratio for complex 2.
The large difference of catalytic activities of Ni(II) com-
plex 1 and Cu(II) complex 2 indicates that the nature of the
metal center has a significant effect on catalytic activity.
Table 1
Norbornene polymerization for the 1/MAO catalytic systema
Run
Al/Ni
t (ꢀC)
Yield (g)
Activityb
Mvc
1
2
3
4
5
6
7
8
9
1000
2000
3000
4000
5000
10,000
4000
4000
4000
4000
30
30
30
30
30
30
15
45
60
75
0.902
1.108
1.341
1.525
1.558
1.908
0.817
1.675
1.117
0.992
1.08
1.33
1.61
1.83
1.87
2.29
0.98
2.01
1.34
1.19
1.65
1.82
1.79
2.18
1.77
1.87
2.32
1.94
1.86
0.98
10
a
Polymerization conditions: [Ni] = 0.1 lmol, [NB] = 3.76 g; time = 5 -
min; Vtotal = 15.0 mL; solvent: chlorobenzene.
b
108 g PNB molꢀ1 Ni hꢀ1
106 g molꢀ1
.
c
Ni(II) complex 1 (up to 2.29 · 108 g PNB molꢀ1 Ni hꢀ1
,
.

F.-T. Chen et al. / Journal of Organometallic Chemistry 692 (2007) 3435–3442
3439
Table 1, Run 6) is more active than the corresponding
Cu(II) complex 2 (up to 3.16 · 105 g PNB molꢀ1 Cu hꢀ1
Table 2, Run 3), which implies that the rate of chain prop-
agation of nickel catalyzed norbornene polymerization is
much faster than that of copper catalyzed norbornene
polymerization.
All polynorbornenes obtained show similar IR spectra.
IR spectra reveal the characteristic signals of polynorborn-
enes at about 943 cmꢀ1. And there are no absorptions at
,
1680–1620 cmꢀ1, especially about 960 and 735 cmꢀ1
,
assigned to the trans and cis forms of double bonds, respec-
tively, which are characteristic of the ROMP structure of
polynorbornenes [24]. These absorption peaks at about
943 cmꢀ1 can be assigned to the ring system of bicy-
cle[2.2.1]heptane, as Kennedy noted [25].
All the polynorbornenes synthesized here are easily sol-
uble in cyclohexane, chlorobenzene and o-dichlorobenzene,
which indicate low stereoregularity. Indeed, analysis by
wide-angle X-ray diffractometry shows no indication of
crystallinity. The attempts to determine the glass transition
temperature (Tg) of polynorbornenes failed, since DSC
studies did not give an endothermic signal upon heating
to 400 ꢀC [11a].
The polymerization results catalyzed by complexes 1 and
2 are higher than that of bis[(N-2,6-diisopropylphenyl)sali-
cylaldiminate]nickel(II) complex (up to 3.5 · 107 g
PNB molꢀ1 Ni hꢀ1
)
and bis(salicylaldiminate)copper(II)
complex (up to 1.5 · 105 g PNB molꢀ1 Cu hꢀ1) [7a,18], espe-
cially for Ni(II) complex 1. The activity of complex 1 is
higher with an order of magnitude than that of bis[(N-2,6-
diisopropylphenyl)salicylaldiminate]nickel(II)
complex.
The difference results from the difference of molecular struc-
ture may be due to the steric hindrance. From Ni(II) complex
1, the longer Ni(1)–O, Ni(1)–N bond distances (1.884(3) and
˚
1.971(2) A) make the coordinate atoms (N or O) easier to be
removed and form the bare coordinate sites, accordingly
benefiting insertion of norbornene.
4. Conclusions
The reaction temperature also considerably affects the
catalytic activities and molecular weight of complexes 1
and 2. With an increase of reaction temperature, the cata-
lytic activities of complexes 1 and2 first increase and then
decrease. For complex 1, the maximum value of activities
is obtained at 45 ꢀC. For complex 2, sharp changes can
be observed and the highest activity is obtained at 60 ꢀC.
For complex 1, Mv of polymers decreases with increase
of reaction temperature, but slight increase for complex 2
with increase of reaction temperature is observed.
The crystal structures show that the four coordination
metal centers of nickel(II) metal (1) and copper(II) (2) com-
plexes with phenoxy-imidazole ligands take the form of dis-
torted tetrahedral and distorted square planar coordination
geometries, respectively. Due to the steric effects of adjacent
groups, a more crowded steric environment for nickel(II)
center makes it obviously deviated from the usual planar
trans-N2O2 coordination geometry.
Preliminary experiments indicated that complexes 1 and
2 can be used as the precursor for the catalysis of norborn-
ene polymerization in the presence of MAO. To the best of
our knowledge, this is one of the catalysts possessing high-
est activities for vinyl addition polymerization of norborn-
ene in reported literatures either to nickel complex or to
copper complex.
The microstructure of the obtained polynorbornene is
1
characterized by H NMR and 13C NMR spectra and IR
1
spectra. The polynorbornene have similar H NMR and
13C NMR spectra. No resonances are displayed at about d
1
5.1 and 5.3 ppm in the H NMR spectrum of the polynor-
bornene, assigned to the cis and trans form of double bonds
[19], which generally indicates the presence of the ring-open-
ing metathesis polymerization (ROMP) structure. The 13C
NMR spectrum shows the main four groups of resonances:
d (51.3, 49.4, 48.8, 46.8, 44.5), 38.5, (37.8, 37.4, 34.7), (30.5,
28.7) ppm, attributed to carbons 2 and 3, carbons 1 and 4,
carbon 7, carbons 5 and 6, respectively (Scheme 1) [20,21].
The 13C NMR spectrum is similar to that reported by Wu
et al. [20] and Patil et al. [7a]. These data indicate that the
polynorbornene obtained with the aforementioned catalysts
was a vinyl-type (2,3-linked) addition product, i.e. no
ROMP was observed. And the 13C NMR spectrum shows
that the polymer is exo enchained; the spectrum does not
exhibit resonances in the d 20–24 ppm region. The presence
of such resonances has been taken as evidence of endo
enchainment on the basis of mode studies [21]. The multiplic-
ity of the peaks suggests that the insertion of monomer units
can take place in more than one stereospecific way, and
therefore the obtained polynorbornenes is atactic [22].
Indeed, all polynorbornenes are soluble at room tempera-
ture in chlorobenzene and cyclohexane, which indicate low
stereoregularity [23].
5. Experimental
5.1. General procedures
All air-sensitive experiments were carried out under nitro-
gen using standard Schlenk and vacuum-line techniques.
Chlorobenzene was dried over CaH2 and distilled under
nitrogen prior to use. Norbornene was purchased from
ACROS and purified by distillation over sodium. Methyl-
aluminoxane (MAO) was purchased from Aldrich as 10%
weight of a toluene solution and used without further purifi-
cation. Other chemicals were of analytical grade and were
used as received. IR spectra were recorded on a Niclolet
FT-IR spectrometer. Element analyses were performed on
an Elementar vario EL III Analyzer. H NMR and 13C
1
NMR spectra were carried out on a Bruker AC 500 spec-
trometer instrument at room temperature in CDCl3 solution
for ligands and complexes, and o-dichlorobenzene-d4 solu-
tion for polymers using TMS as an internal standard. The
intrinsic viscosity [g] was measured in chlorobenzene at
25 ꢀC using an Ubbelohde viscometer. Viscosity average

3440
F.-T. Chen et al. / Journal of Organometallic Chemistry 692 (2007) 3435–3442
molecular weight (Mv) values of polymer were calculated by
the following equation: [g] = 5.97 · 10ꢀ4 Mv0.56 [26,27]. Dif-
ferential scanning calorimetric (DSC) measurements were
performed on a Perkin–Elmer Pyris 1 DSC. The wide-angle
X-ray diffraction (WAXD) diagram of the polymer powders
was obtained using a Bruker D4 Endeavor X-ray diffractom-
eter with monochromatic radiation at a wavelength of
2356(w), 2340(w), 1580(m), 1496(s), 1429(s), 1384(m),
1299(m), 1260(s), 1018(m), 796(m), 779(m), 762(m), 729(s),
698(s). Elemental Anal. Calc. for C70H70CuN4O2 Æ 2CH2Cl2:
C, 70.15; H, 6.05; N, 4.54. Found: C, 70.16; H, 6.13; N,
4.46%.
5.5. X-ray crystallography
˚
1.54 A. Scanning was performed with 2h ranging from 5ꢀ
to 60ꢀ.
Diffraction data of complexes 1 and2 were collected on a
Bruker Smart APEX CCD diffractometer with graphite-
5.2. Synthesis of ligand [20-(40,60-di-tert-butylhydroxy-
phenyl)-1,4,5-triphenyl imidazole] (LH)
monochromated Mo Ka radiation (k = 0.71073 A). All
˚
the data were collected at room temperature and the struc-
tures were solved by direct methods and subsequently
refined on F2 by using full-matrix least-squares techniques
(SHELXL) [28], absorption corrections were applied to the
data. The non-hydrogen atoms were refined anisotropi-
cally, and hydrogen atoms were located at calculated posi-
tions. A summary of the crystallographic data and selected
experimental information is given in Table 3.
Analogous to the literature reported previously [12], a
25 mmol of benzyl and 25 mmol of 3,5-di-tert-butylhydroxy-
benzaldehyde were dissolved in 100 mL glacial acetic acid at
room temperature. Aniline (37.5 mmol) was added dropwise
to this solution, and 125 mmol ammonium acetate was
added subsequently. The mixture was heated at 110 ꢀC for
12 h. After the termination of the reaction, the yellow solu-
tion was poured into a copious amount of water.
Recrystallization from an ethyl acetate solution afforded
5.6. Polymerization of norbornene
1
7.35 g of white powder with a 59% overall yield. H NMR
In a typical procedure (Table 1, Run 5), 0.1 lmol of
nickel complex 1 in 2.0 mL of chlorobenzene, 3.76 g of nor-
bornene in 8.0 mL of chlorobenzene and 5.0 mL of fresh
chlorobenzene were added into a special polymerization
bottle (25 mL) with a strong stirrer under nitrogen atmo-
sphere. After the mixture was kept at 30 ꢀC for 10 min,
0.33 mL of MAO was charged into the polymerization sys-
tem via a syringe and the reaction was started. Five min-
utes later, acidic ethanol (Vethanol:Vconcd.HCl = 20:1) was
(500 MHz,CDCl3, ppm) d 0.90(s, 9H, tBu), 1.49(s, 9H,
tBu), 6.61(d, 1H, ArOHH), 7.19(d, ArOHH), 7.20–7.25(m,
11H, ArH), 7.34(d, 3H, ArH), 7.55(d, 1H, ArH), 13.4-
(1H, OH). IR (kBr, cmꢀ1): m 3419(br), 3061(w), 2957(s),
ꢀ
2906(m), 2867(m), 2641(w), 1560(m), 1485(s), 1441(s),
1395(s), 1360(m), 1251(s), 1278(m), 1227(m), 1187-
(w), 1076(w), 1025(w), 876(w), 849(m), 768(m), 697(s),
668(w). Elemental Anal. Calc. for C35H36N2O: C, 83.96;
H, 7.25; N, 5.60. Found: C, 83.89; H, 7.21; N, 5.60%.
5.3. Synthesis of nickel complexes (NiL2) (1)
Table 3
Crystal data and structure refinement for complexes 1 and 2
To a solution of ligand (LH) (4 mmol, 1.868 g) in 20 mL
of THF was added dropwise a 1.6 M solution of BuLi in
Complex
1
2
n
Formula
Fw
C
72H74Cl4N4NiO2 C72H74Cl4CuN4O2
hexane (4 mmol, 2.5 mL). A light yellow solution was
obtained. After 2 h of reaction, the resulting lithium salt
solution was added dropwise to the suspension of anhy-
drous NiCl2 (2 mmol, 0.259 g) in 20 mL CH2Cl2; a dark
red solution was formed, then stirred for 6 h at room tem-
perature. The solution obtained was dried in vacuo, and
the residue was extracted with 30 mL of dichloromethane
and recrystallized from a dichloromethane/hexane solution
at room temperature to give complex 1 as yellow crystals in
46% yield. IR (KBr, cmꢀ1): ꢀm 3059(w), 2950(s), 2904(m),
2866(m), 2364(w), 1600(m), 1497(s), 1458(m), 1384(m),
1310(m), 1262(s), 1075(w), 919(w), 794(w), 768(m), 699(s).
Elemental Anal. Calc. for C70H70NiN4O22CH2Cl2: C,
70.43; H, 6.07; N, 4.56. Found: C, 70.79; H, 6.28; N, 4.51%.
1227.86
Monoclinic
C2/c
28.473(10)
13.024(5)
18.500(7)
90
108.064(5)
90
6522(4)
4
1.250
0.509
2584
16,004
7157
1232.69
Monoclinic
C2/c
27.231(7)
12.303(3)
19.897(5)
90
103.575(4)
90
6480(3)
4
1.264
0.550
2588
16,003
7085
Crystal system
Space group
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢀ)
b (ꢀ)
c (ꢀ)
3
˚
V (A )
Z
qcalcd (Mg mꢀ3
)
l (mmꢀ1
F(000)
)
Reflections collected
Independent reflections
R(int)
Data/restraints/parameters
GOF on F2
0.0588
7157/0/381
0.939
0.0784
7085/0/381
0.773
5.4. Synthesis of copper complexes (CuL2) (2)
a
R1, wR2 [I > 2r(I)]
0.0596, 0.1525
0.0580, 0.1089
Largest difference in peak and
0.546 and ꢀ0.473 1.069 and ꢀ0.376
Analogous synthesis to 1, except that anhydrous CuBr2
ꢀ3
˚
hole (e A
)
instead of anhydrous NiCl2. Green crystals in 61% yield.
P
P
P
P
a
R1 = (||Fo| ꢀ |Fc||)/ |Fo|, wR2 = [ (|Fo|2 ꢀ |Fc|2)2/ (Fo2)]1/2
.
IR (KBr, cmꢀ1): m 3063(w), 2959(s), 2899(m), 2863(m),
ꢀ

F.-T. Chen et al. / Journal of Organometallic Chemistry 692 (2007) 3435–3442
3441
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added to terminate the reaction. The PNB was isolated by
filtration, washed with ethanol and dried at 80 ꢀC for 48 h
under vacuum. For all polymerization procedures, the total
reaction volume was 15.0 mL, which can be achieved by
the variation of the amount of chlorobenzene when neces-
sary. IR (KBr): 2944, 2871, 1474, 1451, 1377, 1296, 1260,
1220, 1141, 1102, 1020, 940, 902, 864, 800 cmꢀ1 1H
.
(j) Q.-Z. Yang, A. Kermagoret, M. Agostinho, O. Siri, P. Braunstein,
Organometallics 25 (2006) 5518.
NMR: d 0.7–3.0 (m, maxima at 1.29 1.71 2.05 2.36 ppm).
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Acknowledgements
(c) B. Berchtold, V. Lozan, P.-G. Lassahn, C. Janiak, J. Polym. Sci.
Part A: Polym. Chem. 40 (2002) 3604;
(d) C. Janiak, P.G. Lassahn, V. Lozan, Macromol. Symp. 236 (2006)
88.
Financial support by the National Science Foundation
of China for Distinguished Young Scholars (20421303,
20531020), by the National Basic Research Program of
China (2005CB623800) and by Shanghai Science and Tech-
nology Committee (05JC14003, 05DZ22313) is gratefully
acknowledged.
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(Idemitsu Kosan) (1991), Chem. Abstr. 115 (1991) 256943g;
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Appendix A. Supplementary material
CCDC 636922 and 636923 contain the supplementary
crystallographic data for 1 and 2. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
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