Synthesis, molecular structures and norbornene addition polymerization activity of the neutral nickel catalysts supported by N-naphthyl- salicylaldiminato ligands

Article abstract of DOI:10.1016/j.inoche.2004.11.025

3-R₁-5-R₂-(naphthyl-NCH)-C₆H ₂O]Ni(Ph)(PPh₃) can be used as catalysts for the addition polymerization of norbornene in the presence of methylaluminoxane as co-catalyst in high activities. A series of nickel Schiff-base complexes were synthesized by the reaction of Schiff-bases containing N-naphththyl group with trans-[Ni(PPh₃)₂(Ph)Cl] and they were characterized by EA, IR and NMR. When activated by methylaluminoxane, these complexes exhibit good catalytic activity for the addition polymerization of norbornene.

Full text of DOI:10.1016/j.inoche.2004.11.025

Inorganic Chemistry Communications 8 (2005) 109–112
www.elsevier.com/locate/inoche
Synthesis, molecular structures and norbornene
addition polymerization activity of the neutral nickel
catalysts supported by N-naphthyl-salicylaldiminato ligands
*
Wei-Hua Wang, Guo-Xin Jin
Department of Chemistry, Laboratory of Molecular Catalysis and Innovative Materials, Fudan University,
Handan Road 220, Shanghai 200433, PR China
Received 5 November 2004; accepted 16 November 2004
Abstract
A series of nickel Schiff-base complexes were synthesized by the reaction of Schiff-bases containing N-naphththyl group with
trans-[Ni(PPh3)2(Ph)Cl] and they were characterized by EA, IR and NMR. When activated by methylaluminoxane, these complexes
exhibit good catalytic activity for the addition polymerization of norbornene.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Nickel; Catalysts; Molecular structure; Polymerization; Polynorbornene
Late transition metal catalysts have been one of the
most exciting developments in the area of catalysis,
organometallic chemistry, and polymer science in recent
years [1]. Ni-based catalyst was best known to oligomer-
ize ethylene and dimerize propylene and higher a-olefins
because nickel metal was usually thought to generally
prefer b-hydride elimination followed by reductive elim-
ination before 1995 [2], however, the discovery of sali-
cylaldiminato nickel complexes as high active catalysts
for polymerization of olefin has become a great break-
through [3].
During the past few years, most of our effort has
focused on neutral, single-component nickel ethylene-
polymerization catalysts before we began our cyclo-ole-
fins polymerization study. Several series of nickel
catalysts supported by [N, O] mono-anionic and bis-
anionic ligands, including salicylaldiminato phenyl
nickel complexes [4] and binuclear 2,5-disubstituteda-
mino-p-benzoquinone nickel(II) complexes [5], were
designed and synthesized on the basis of recent devel-
opments. And these neutral nickel complexes based
on anion ligands are very reactive toward ethylene.
Deming and Novak [6] introduced the first nickel com-
plexes for the addition polymerization of norbornene
in 1993 and recently several other catalyst systems
are presented [7]. This paper aims to investigate what
effect can be brought in by replacement of the phenyl
with naphthyl group in the imino moiety of salicylal-
diminato nickel complexes, since the latter has a larger
conjugated system (Scheme 1). Polymerizations of nor-
bornene were carried out with these complexes as
catalysts in the presence of methylaluminoxane as a
co-catalyst.
The complexes were prepared as shown in Scheme 1,
including 4e to make comparison, the preparation pro-
cedures were according to the analogous method of ref-
erence [3b]. All complexes were characterized by EA, IR
*
Corresponding author. Tel.: +86 21 65643776; fax: +86 21
65641740.
1
and H NMR [8]. In the IR spectra of complexes, the
E-mail address: gxjin@fudan.edu.cn (G.-X. Jin).
1387-7003/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2004.11.025

110
W.-H. Wang, G.-X. Jin / Inorganic Chemistry Communications 8 (2005) 109–112
R
CHO
N-Ar
R
CH
OH
2
2
Ar-NH2
H+/EtOH
OH
R
R
1
1
2a-e
1a-e
NaH/THF
Ar
CH
O
R
2
R
2
CH
N-Ar
N
trans-[Ni(PPh3)2(Ph)Cl]
benzene
Ph
Ni
ONa
PPh
3
R
1
R
1
4a-e
3a-e
a: R1=H, R2=H, Ar=Naphthyl
b: R1=t-Bu, R2=H, Ar=Naphthyl
c: R1=H, R2=OCH3, Ar=Naphthyl
d: R1=NO2, R2=NO2, Ar=Naphthyl
e: R1=H, R2=H, Ar=Phenyl
Scheme 1. Synthesis of complexes 4a–4e.
˚
Fig. 2. Molecular structure of complex 4c. Selected bond lengths (A)
and angles (ꢁ): Ni(1)–C(19) 1.887(4), Ni(1)–O(1) 1.896(3), Ni(1)–N(1)
1.946(3), Ni(1)–P(1) 2.184(2), N(1)–C(35) 1.288(4) and C(19)–Ni(1)–
O(1) 175.13(13), C(19)–Ni(1)–N(1) 90.33(13), O(1)–Ni(1)–N(1)
91.60(11), C(19)–Ni(1)–P(1) 85.32(11), O(1)–Ni(1)–P(1) 93.12(9),
N(1)–Ni(1)–P(1) 173.50(8).
˚
Fig. 1. Molecular structure of complex 4a. Selected bond lengths (A)
and angles (ꢁ): Ni(1)–O(1) 1.8808(17), Ni(1)–C(19) 1.892(2), Ni(1)–
N(1) 1.937(2), Ni(1)–P(1) 2.1696(10), N(1)–C(35) 1.292(3) and O(1)–
Ni(1)–C(19) 176.60(9), O(1)–Ni(1)–N(1) 91.59(8), C(19)–Ni(1)–N(1)
91.73(9), O(1)–Ni(1)–P(1) 91.10(6), C(19)–Ni(1)–P(1) 85.57(7), N(1)–
Ni(1)–P(1) 177.15(6).
bands of C@N are shifted to lower frequencies for differ-
ent amounts, respectively, due to the coordination be-
tween azomethine nitrogen and nickel.
The ORTEP diagrams of 4a and 4c are shown in
Figs. 1 and 2, respectively [9], along with selected bond
lengths and angles.

W.-H. Wang, G.-X. Jin / Inorganic Chemistry Communications 8 (2005) 109–112
111
Table 1
Results of norbornene polymerization initiated by catalysts 4a–e
b
Mn (g/mol)
b
Run
Cat
T (ꢁC)
Yield (%)
Activity (g-PNB/mol-Ni Æ h)
Mv (g/mol)
Mw/Mn
1
2
3
4
5
6
7
8
9
4b
4b
4b
4b
4b
4a
4c
4d
4e
0
15
30
45
60
30
30
30
30
39.25
46.31
65.06
60.81
64.21
60.38
56.35
67.50
29.63
2.22 · 107
2.62 · 107
3.68 · 107
3.44 · 107
3.63 · 107
3.41 · 107
3.18 · 107
3.81 · 107
1.67 · 107
1.19 · 105a
1.37 · 106a
2.58 · 106b
4.70 · 105a
4.06 · 105a
2.17 · 106b
2.63 · 106b
1.95 · 106b
2.06 · 106b
1.07 · 106
2.72
7.77 · 105
1.07 · 106
5.98 · 105
7.71 · 105
3.22
2.79
3.81
3.05
Polymerization conditions: reaction volume: 15 ml; time: 10 min; solvent: chlorobenzene; [Al]/[Ni] = 2665; [Ni] = 1.33 · 10À5 mol/l; [NBE]/[Ni] =
100 000.
a
Obtained by capillary viscosimetry using the Mark–Houwink coefficients: a = 0.56, K = 7.78 · 10À4dl/g [11a].
Obtained by GPC [11b].
b
The molecule of 4a adopts a nearly ideal square-pla-
nar coordination geometry with the Ni approximately
˚
0.091 A out of the plane of its ligands. The 1-naphthy-
for Distinguished Young Scholars (Grant Nos.
29925101, 20274008) and from the Key Project of Sci-
ence and Technology of the Education Ministry of
China.
limido-group occupies the position trans to the triphe-
nylphosphine ligand with a nearly linear N(1)–Ni–P(1)
angle (177.15(6)ꢁ). The Ni(1)–P(1) bond distance
˚
(2.1696(10) A) is between that in Grubbsꢀ nickel-based
References
˚
complex (d(Ni–P) 2.172(2) A) and that in Cavellꢀs [Ni(P-
Ph3)(o-tolyl)(N–O)] complex with N–O bidentate pyri-
[1] (a) S.D. Ittel, L.K. Johnson, M. Brookhart, Chem. Rev. 100
(2000) 1169;
˚
dinecarboxylate ligand (d(Ni–P) 2.1653(2) A) [3b,10].
(b) G.W. Coates, Chem. Rev. 100 (2000) 1223;
(c) S. Mecking, Coord. Chem. Rev. 203 (2000) 325;
(d) V.C. Gibson, S.K. Spitzmesser, Chem. Rev. 103 (2003) 283.
[2] (a) L.K. Johnson, C.M. Killian, M. Brookhart, J. Am. Chem.
Soc. 117 (1995) 6414;
The coordination sphere of complex 4c was found to
be alike (Fig. 2), the Ni(1), N(1), O(1), P(1), C(19) atoms
˚
are coplanar (mean deviation, 0.0636 A). One benzene
molecule is incorporated in a unit cell.
The catalyst of 4b showed quite good activities over a
wide range (0–60 ꢁC) of reaction temperature, the activ-
ity increased with higher temperature and reached a pla-
teau around 30 ꢁC. Except for 0 ꢁC, the molecular
weight of the obtained polymer declined with higher
temperature. The reason for this exception might be
plausibly attributed to that under low temperature, the
propogation of the polymer chain could not be fully
developed in 10 min (see Table 1).
The structures of the neutral Ni(II) complexes clearly
affected the activities. Since naphthyl group is a two-ring
conjugated system while phenyl is a one-ring conjugated
system, replacement of phenyl with naphthyl in the mol-
ecule might bring an electron property modification to
the complex. All of 4a–d showed a higher activity
roughly doubled that of 4e. The resulted polymers are
soluble in chlorobenzene at room temperature.
Although different molecular weights were obtained by
changing reaction conditions, same spectra were ob-
served for those polynorbornenes [12].
(b) D.P. Gates, S.A. Svejda, E. Onate, C.M. Killian, L.K.
Johnson, P.S. White, M. Brookhart, Macromolecules 33 (2000)
2320;
(c) Z. Guan, P.M. Cotts, E.F. McCord, S.J. McLain, Science 283
(1999) 2059;
(d) C.M. Killian, D.J. Tempel, L.K. Johnson, M. Brookhart, J.
Am. Chem. Soc. 118 (1996) 11664.
[3] (a) R. Soula, J.P. Broyer, M.F. Llauro, A. Tomov, R. Spitz, J.
Claverie, X. Drujon, J. Malinge, T. Saudemont, Macromolecules
34 (2001) 2438;
(b) C. Wang, S. Friedrich, T.R. Younkin, R.T. Li, R.H.
Grubbs, D.A. Bansleben, M.W. Day, Organometallics 17 (1998)
3149;
(c) T.R. Younkin, E.F. Connor, J.I. Henderson, S.K. Friedrich,
R.H. Grubbs, D.A. Bansleben, Science 287 (2000) 460.
[4] (a) D. Zhang, G.X. Jin, Chem Commun. (2002) 574;
(b) D. Zhang, G.X. Jin, Eur. J. Inorg. Chem. (2003) 1570;
(c) D. Zhang, G.X. Jin, Appl. Catal. A: General 262 (2004) 13;
(d) D. Zhang, G.X. Jin, Appl. Catal. A: General 262 (2004) 85;
(e) G.X. Jin, D. Zhang, J. Polym. Sci. Polym. Chem. 42 (2004)
1018.
[5] D. Zhang, G.X. Jin, Organometallics 22 (2003) 2851.
[6] T.J. Deming, B.M. Novak, Macromolecules 26 (1993) 7089.
[7] (a) A.O. Patil, S. Zushma, R.T. Stibrany, S.P. Rucker, L.M.
Wheeler, J. Polym. Sci. Part A: Polym. Chem. 41 (2003) 2095;
(b) X.F. Li, Y.S. Li, J. Polym. Sci. Part A: Poly. Chem. 40 (2002)
2680;
Acknowledgements
(c) W.H. Sun, H. Yang, Z. Li, Y. Li, Organometallics 22 (2003)
3678;
We gratefully acknowledge the financial supports
from the National Nature Science Foundation of China
(d) V. Lozan, P.G. Lassahn, C. Zhang, B. Wu, C. Janiak, G.
Rheinwald, Z. Lang, Z. Naturforsch. B 58 (2003) 1152;

112
W.-H. Wang, G.-X. Jin / Inorganic Chemistry Communications 8 (2005) 109–112
(e) G.M. Benedikt, E. Elce, B.L. Goodall, H.A. Kalamarides,
(400 MHz, CDCl3): d 2.17 (s, 9H, t-Bu), 5.30–8.35 (m, 30H,
aromatic-H), 8.58 (s, 1H, CH@N). IR (KBr pellet, m (cmÀ1)):
1583.5 (s). Anal. Calc. for C45H40NOPNi: C, 77.16; H, 5.76; N,
2.00. Found: C, 77.26; H, 5.79; N, 2.10. 4c (66.7% yield). 1H NMR
(400 MHz, CDCl3): d 3.69 (s, 3H, OCH3), 5.48–8.28 (m, 30H,
aromatic-H), 8.63 (s, 1H, CH@N). IR (KBr pellet, m (cmÀ1)):
1615.4 (s). Anal. Calc. for C42H34NO2PNi Æ 1/2C6H6: C, 75.76; H,
5.23; N, 1.96. Found: C, 75.44; H, 5.21; N, 1.50. 4d (70.8% yield).
1H NMR (400 MHz, CDCl3): d 5.53–8.34 (m, 29H, aromatic-H),
8.60 (s, 1H CH@N). IR (KBr pellet, m (cmÀ1)): 1615.5(s). Anal.
Calc. for C41H30N3O5PNi: C, 67.06; H, 4.12; N, 5.72. Found: C,
67.19; H, 4.15; N, 5.56. 4e (80.8% yield). 1H NMR (400 MHz,
CDCl3): d 5.60–8.10 (m, 29H, aromatic-H), 8.64 (s, 1H, CH@N).
IR (KBr pellet, m (cmÀ1)): 1610.2 (s). Anal. Calc. for C37H30NOP-
Ni Æ 1/2C6H6: C, 75.86; H, 5.25; N, 2.21. Found: C, 75.93; H, 5.71;
N, 2.43.
L.H. McIntosh, L.F. Rhodes, K.T. Selvy, C. Andes, K. Oyler, A.
Sen, Macromolecules 35 (2002) 8979;
(f) X. Mi, Z. Ma, N. Cui, L. Wang, Y. Ke, Y. Hu, J. Appl. Poly.
Sci. 88 (2003) 3273;
(g) D. Zhang, G.X. Jin, L.H. Weng, F.S. Wang, Organometallics
23 (2004) 3270.
[8] To a stirred solution of salicylaldehyde (26.8 mmol) in dried
ethanol (40 ml), 1-naphthylamine (4.32 g, 30.2 mmol) and formic
acid (0.5 ml) were added. The reaction mixture was stirred for 24 h
at room temperature. Subsequently, the solution was concentrated
and the brown precipitate was separated by filtration, then
purified with column chromatography on silica gel eluting with
petroleum ether/ethyl acetate (10:1) to afford 2a as yellow solid
(4.19 g). The other ligands were prepared by similar procedures,
except for that they were refluxed for 2 h instead of stirred for 24 h
at room temperature. 2a (63.2% yield). 1H NMR (500 MHz,
CDCl3): d 6.98–8.25 (m, 11H, aromatic-H), 8.70 (s, 1H, CH@N),
13.37 (s, 1H, OH). IR (KBr pellet, m (cmÀ1)): 1621.8 (s). Anal.
Calc. for C17H13NO: C, 82.57; H, 5.30; N, 5.66. Found: C, 82.66;
H, 5.30; N, 5.60. 2b (73.3% yield). 1H NMR (500 MHz, CDCl3): d
1.52 (s, 9H, t-Bu), 6.91–8.30 (m, 10H, aromatic-H), 8.72 (s, 1H,
CH@N), 13.92 (s, 1H, OH). IR (KBr pellet, m (cmÀ1)): 1606.0 (s).
Anal. Calc. for C21H21NO: C, 83.14; H, 6.98; N, 4.61. Found: C,
83.14; H, 7.05; N, 4.72. 2c (68.8% yield). 1H NMR (400 MHz,
CDCl3): d 3.78 (s, 3H, OCH3), 6.97–8.19 (m, 10H, aromatic-H),
9.00 (s, 1H, CH@N), 12.41 (s, 1H, OH). IR (KBr pellet, m (cmÀ1)):
1618.9 (s). Anal. Calc. for C18H15NO2: C, 77.96; H, 5.45; N, 5.04.
Found: C, 77.77; H, 5.41; N, 4.79. 2d (74.2% yield). 1H NMR (400
MHz, DMSO): d 6.95–8.18 (m, 7H, naphthyl-H), 8.87 (s, 1H,
subst. phenyl-H), 8.92 (s, 1H, subst. phenyl-H), 9.68 (s, 1H,
CH@N), 2.8–4.2 (br, exchangeable with D2O). IR (KBr pellet, m
(cmÀ1)): 1620.4 (s). Anal. Calc. for C17H11N3O5: C, 60.55; H, 3.29;
N, 12.44. Found: C, 60.62; H, 3.25; N, 12.51.A solution of ligand
2a (0.495 g, 2 mmol) in THF (20 ml) was added to excess amount
of NaH. The resulting mixture was stirred at room temperature
for 2 h, then filtered. And the filtrate was evaporated. The
greenish-yellow residue was washed with hexane (20 ml) and dried
in vacuum, yielding the Na salt 3a as yellow powder. The Na salt
3a (0.295 g, 1.097 mmol) and trans-[Ni(PPh3)2(Ph)Cl] (0.733 g,
1.053 mmol) were jointed together in a Schlenk flask, 20 ml of
benzene was added, then stirred at room temperature for 8 h. The
reaction mixture was filtered by cannula filtration, and the filtrate
was concentrated in vacuo to ca. 5 ml. Then 30 ml of hexane was
added and a yellow-orange solid precipitated from solution and
was isolated by cannula filtration, then washed several times with
hexane to yield 0.608 g (0.944 mmol) of 4a. The other nickel
complexes 4b-e were prepared by analogous procedures. 4a (89.6%
ꢀ
[9] Crystal data for 4a: C41 H32NNiOP, Mr = 644.36, Triclinic, P1
˚
a = 10.633(4), b = 11.405(4), c = 14.924(5) A, a = 69.687(4)ꢁ,
3
˚
b = 70.648(4)ꢁ, r = 83.103(4)ꢁ, V = 1601.2(9) A , Z = 2,
F(000) = 672, Dcalc = 1.336 g cmÀ3, Of 7231 data collected, 6082
were unique. [Rint = 0.0158]. Final
R
indices [I > 2r(I)],
R1 = 0.0396, wR2 = 0.0904. Crystal data for 4c: C45H37NNiO2P,
ꢀ
Mr = 713.44, Triclinic, P1, a = 11.386(13), b = 13.215(14), c =
˚
13.971(16) A, a = 65.645(15)ꢁ, b = 70.681(15)ꢁ, k = 87.220(16)ꢁ,
3
V = 1798(3) A , Z = 2, F(000) = 746, Dcalc = 1.318 g cmÀ3, of
˚
7618 data collected, 6245 were unique. [Rint = 0.0217]. Final R
indices [I > 2r(I)], R1 = 0.0492, wR2 = 0.1040. All the data were
collected on a CCD-Bruker Smart diffractometer using graphite
˚
monochromated Mo-Ka radiation (k = 0.71073 A) at room
temperature using the x scan technique. The structures were
solved by the direct method, expanded using Fourier techniques
and refined on F2 by a full-matrix least-squares method. Aniso-
tropic displacement parameters were included for all non-hydro-
gen atoms. All the calculations were carried out with Siemens
SHELXTL PLUS program. Crystallographic data for the struc-
tural analysis have been deposited with the Cambridge Crystal-
lographic Data Center CCDC Nos. 248435 and 248436.
[10] S.Y. Desjardins, K.J. Cavell, J.L. Hoare, B.W. Skelton, A.N.
Sobolev, A.H. White, W. Keim, J. Organomet. Chem. 544 (1997)
163.
[11] (a) C. Mast, M. Krieger, K. Dehnicke, A. Greiner, Macromol.
Rapid Commun. 20 (1999) 232;
(b) Determined using a PL GPC-220 gel permeation chromato-
graph at 150 ꢁC with narrow standard calibration and equipped
with three PL gel columns (sets of PL gel 10 lm Mixed-B LS),
and 1,2,4-trichlorobenzene was used as solvent at a flow rate of
1.00 ml/min.
[12] Spectra of the resulted polynorbornenes: IR (KBr pellet, m
(cmÀ1)): 2944.6 (vs), 2867.6 (vs), 1474.4 (m), 1453.0 (s), 1294.1
(m). 1H NMR (o-dichlorobenzene-d4): d = 1.0–2.7 ppm (m,
maxima at 1.31, 1.55, 1.71, 2.46). 13C NMR (o-dichlorobenzene-
d4): d = 29–52 ppm (m, maxima at 31.1, 38.1, 47.1).
yield). 1H NMR (500 MHz, CDCl3):
d 5.45–8.25 (m,31H,
aromatic-H), 8.62 (s, 1H, CH@N). IR (KBr pellet, m (cmÀ1)):
1605.1 (s). Anal. Calc. for C41H32NOPNi: C, 76.42; H, 5.01; N,
2.17. Found: C, 76.15; H, 4.89; N, 2.13. 4b (68.2% yield). 1H NMR