Nickel(II) Isocyanide complexes as ethylene polymerization catalysts

Article abstract of DOI:10.1021/om0498394

Isocyanide complexes of nickel, NiBr₂(CNAr)₂, are found to be active catalysts for polymerization of ethylene in the presence of methylaluminoxane (MAO). The catalytic activity and properties of polyethylene formed vary with substitu

Full text of DOI:10.1021/om0498394

3976
Organometallics 2004, 23, 3976-3981
Nick el(II) Isocya n id e Com p lexes a s Eth ylen e
P olym er iza tion Ca ta lysts
Masao Tanabiki,§ Kazuhiro Tsuchiya,‡ Yasuaki Kumanomido,‡
Kouki Matsubara,† Yukihiro Motoyama,† and Hideo Nagashima*,†,‡
Institute for Materials Chemistry and Engineering, Graduate School of Engineering Sciences,
Kyushu University, Kasuga, Fukuoka, 816-8580, J apan, and Yokkaichi Research Laboratory,
TOSOH Corporation, 1-8, Kasumi, Yokkaichi, Mie, 510-8540, J apan
Received March 4, 2004
Isocyanide complexes of nickel, NiBr2(CNAr)2, are found to be active catalysts for
polymerization of ethylene in the presence of methylaluminoxane (MAO). The catalytic
activity and properties of polyethylene formed vary with substituents on the aryl group, in
particular, at the 2- or 2,6-positions. The nickel complexes having 2,6-diphenylphenyliso-
cyanide and its analogues are catalysts showing moderate activity and giving high molecular
weight polyethylene (Mv > 106), whereas those bearing 2-phenylphenylisocyanide and its
analogues give polyethylene with Mw ) 103-104.
In tr od u ction
tion of the resulting activated Si species to a carbon-
carbon double or triple bond.4 In other words, molecular
catalysis of metal isocyanides may be discovered by
appropriate design of the isocyanide ligands.
Isocyanides (CNR) are similar in their electronic
structures to carbon monoxide (CO), but have stronger
σ-donor and weaker π-acceptor properties as ligands of
transition metal complexes.1 Since their properties as
a ligand depend on the steric and electronic factors of
R groups in CNR, the ligand design of metal isocyanides
as a key to controlling the catalysis may open an
attractive research area in organometallic chemistry.
However, high reactivity of CNR to metal-catalyzed self-
polymerization2 or insertion between O-H, N-H, and
C-H bonds in certain organic molecules prevents stud-
ies using metal isocyanide complexes as catalysts for
chemical transformation of organic molecules.3 A no-
table exception is a report by Ito and co-workers, in
which palladium complexes bearing certain bulky alkyl
isocyanides are excellent catalysts for the activation of
a Si-Si bond followed by intramolecular addition reac-
In this paper, we wish to report that Ni(II) isocyanide
complexes unexpectedly behave as catalysts for ethylene
polymerization in the presence of methylaluminoxane
(MAO). Organonickel complexes had long been recog-
nized as good catalysts for oligomerization of ethylene
including industrial production of C4-C20 olefins5,6
until Brookhart’s discovery that judicious choice of the
ligand structure in MX2(R-diimine) (M ) Ni, Pd) made
it possible to obtain polyethylene with high molecular
weight.7,8 Since then, nickel complexes bearing ana-
logues of bidentate diimine ligands,9 bidentate phos-
phine ligands,10 P∧O or P∧N chelate ligands,11 N∧O
chelate ligands,12 and several carbon-based ligands13
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Heinicke, J .; Koesling, M.; Bru¨ll, R.; Keim, W.; Pritzkow, H. Eur. J .
Inorg. Chem. 2000, 299. (c) Klabunde, U.; Mulhaupt, R.; Herskovitz,
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2000, 33, 2320.
* Corresponding author. E-mail: nagasima@cm.kyushu-u.ac.jp.
† Institute for Materials Chemistry and Engineering, Kyushu
University.
‡ Graduate School of Engineering Sciences, Kyushu University.
§ Yokkaichi Research Laboratory, TOSOH Corporation.
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10.1021/om0498394 CCC: $27.50 © 2004 American Chemical Society
Publication on Web 07/09/2004

Nickel(II) Isocyanide Complexes
Organometallics, Vol. 23, No. 16, 2004 3977
Sch em e 1. Syn th esis of Nick el Isocya n id e Com p lexes
have been reported as an active molecular catalyst for
olefin polymerization, in which design of the ligand
structure is crucially important for chain growth of
polyethylene.14 In our recent finding that treatment of
NiBr2(CNAr)2 with MAO produces active species for the
formation of polyethylene with Mw ) 103 to >106 with
Mw/Mn ) 1.8-3.2 with moderate catalytic activity (1-
633 g/mmol Ni‚h), the ligand structures, particularly,
substituents on the aryl group in the isocyanide ligands
in the Ni(II) isocyanide complexes, apparently affect the
catalytic activity and the molecular weight and number
of methyl branches of the formed polymers. In other
words, the nickel isocyanide complexes with appropriate
ligand structures have made possible for the first time
catalytic polymerization of ethylene, opening a new
potential for metal isocyanides in molecular catalysis.
(11) (a) Liu, W.; Malinoski, J . M.; Brookhart, M. Organometallics
2002, 21, 2836. (b) Held, A.; Bauers, F. M.; Mecking, S. Chem.
Commun. 2000, 301. (c) Soula, R.; Broyer, J . P.; Llauro, M. F.; Tomov,
A.; Spitz, R.; Claverie, J .; Drujon, X.; Malinge, J .; Saudemont, T.
Macromolecules 2001, 34, 2438. (d) Gibson, V. C.; Tomov, A.; White,
A. J . P.; Williams, D. J . Chem. Commun. 2001, 719. (e) Gibson, V. C.;
Tomov, A. Chem. Commun. 2001, 1964. (f) Komon, Z. J . A.; Bu, X. H.;
Bazan, G. C. J . Am. Chem. Soc. 2000, 122, 1830. (g) Rachita, M. J .;
Huff, R. L.; Bennett, J . L.; Brookhart, M. J . Polym. Sci. Polym. Chem.
2000, 38, 4627. (h) Guan, Z.; Marshall, W. J . Organometallics 2002,
21, 3580. (i) Komon, Z. J . A.; Bazan, G. C. Macromol. Rapid Commun.
2001, 22, 467. (j) Daugulis, O.; Brookhart, M. Organometallics 2002,
21, 5926.
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K.; Grubbs, R. H.; Bansleben, D. A. Science 2000, 287, 460. (b) Wang,
C. M.; Friedrich, S.; Younkin, T. R.; Li, R. T.; Grubbs, R. H.; Bansleben,
D. A.; Day, M. W. Organometallics 1998, 17, 3149. (c) Bauers, F. M.;
Mecking, S. Macromolecules 2001, 34, 1165. (d) Hicks, F. A.; Brookhart,
M. Organometallics 2001, 20, 3217. (e) J enkins, J . C.; Brookhart, M.
Organometallics 2003, 22, 250. (f) Hicks, F. A.; J enkins, J . C.;
Brookhart, M. Organometallics 2003, 22, 3533. (g) Desjardins S. Y.;
Cavell, K. J .; Hoare, J . L.; Skelton, B. W.; Sobolev, A. N.; White, A.
H.; Keim, W. J . Organomet. Chem. 1997, 544, 163. (h) Shim, C. B.;
Kim, Y. H.; Lee, B. Y.; Dong, Y.; Yun, H. Organometallics 2003, 22,
4272. (i) Lee, B. Y.; Kim, Y. H.; Shin, H. J .; Lee, C. H. Organometallics
2002, 21, 3481.
Resu lts a n d Discu ssion
Although the synthesis of NiX2(CNR)2 was reportedly
achieved by treatment of NiX2 with CNR,15,16c we found
that NiBr2(dme) (dme ) 1,2-dimethoxyethane) was a
versatile precursor for preparation of NiBr2(CNAr)2
(1d -11d , Scheme 1) in CH2Cl2 in good yields. Struc-
tures of the isocyanide ligands, in particular, those
having substituents at the 2- and/or 6-positions, are
important for this study, and several novel aryl-
substituted isocyanides are synthesized by the Suzuki
coupling of bromoanilines with arylboronic acids fol-
lowed by formylation and dehydration as shown in
(15) (a) Otsuka, S.; Nakamura, A.; Tatsuno, Y. J . Am. Chem. Soc.
1969, 91, 6994.
(16) (a) Mayr, A.; Mao, L.-F. Inorg. Chem. 1998, 37, 5776. (b) Lu,
Z.-L.; Mayr, A.; Cheung, K.-K. Inorg. Chim. Acta 1999, 284, 205. (c)
Yamamoto, Y.; Ehara, K.; Takahashi, K.; Yamazaki, H. Bull. Chem.
Soc. J pn. 1991, 64, 3376.
(13) (a) Longo, P.; Grisi, F.; Proto, A.; Zambelli, A. Macromol. Rapid
Commun. 1998, 19, 31. (b) Dubois, M. A.; Wang, R. P.; Zargarian, D.;
Tian, J .; Vollmerhaus, R.; Li, Z. M.; Collins, S. Organometallics 2001,
20, 663.
(14) Gibson, V. C. Spitzmesser, S. K. Chem. Rev. 2003, 103, 283.

3978 Organometallics, Vol. 23, No. 16, 2004
Tanabiki et al.
lytic activity (entries 3 and 4). A similar change in the
molecular weight of the product dependent on the aryl
group of the ligand is also seen in the polymerization
with the Brookhart catalyst.9 In all cases, polyethylene
formed has a relatively narrow molecular weight dis-
tribution (Mw/Mn ) 2.1-3.2).
A remarkable increase in the catalytic activity was
discovered when 2-aryl or 2,6-diarylphenyl isocyanides
were used as the ligand of Ni(II) complexes. As shown
in Table 1, entries 5 and 6, 2-phenyl-substituted com-
plex 5d showed relatively high catalytic activity [223
g/mmol Ni‚h by 10 µmol of the catalyst (Al/Ni ) 100/1)]
to produce the polymer with Mw ) 2200 (Mw/Mn ) 1.8).
Use of 1 µmol of the catalyst (Al/Ni ) 1000/1) resulted
in production of polyethylene with 633 g/mmol Ni‚h of
activity. The higher Al/Ni ratio somewhat increased the
catalytic activity. For example, the tert-butylphenyl
anologue of 5d , 7d , showed an activity of 80.0 and 198
g/mmolNi‚h with the Al/Ni ratio of 100/1 and 1000/1,
respectively. The 2,6-disubstituted complex 6d showed
lower catalytic activity (47 g/mmol Ni‚h with 10 µmol
of the catalyst) than 3d . Although the catalytic activity
was lower, it was surprising that the molecular weight
of formed polyethylene was too large to be determined
by our GPC system. The viscosity average molecular
weight (Mv) of polyethylene formed by the catalyst 6d
was estimated by the intrinsic viscosity [η] measure-
ment to be 6 100 000. Since Mw is higher than Mv,
existence of two phenyl group at ortho-positions in the
phenylisocyanide ligand in 6d caused production of
polyethylene of Mw > ca. 6 × 106. In both of the
catalysts, the formed polyethylene has a small number
of methyl branches.17 In particular, polymer obtained
by 6d is almost linear.
To look at further aspects of the substituent effects
of the isocyanide ligands, we prepared a series of Ni(II)
complexes having 2-aryl and 2,6-diarylphenylisocyanide
ligands, shown in Chart 1. The results of polymerization
of ethylene using these catalysts are summarized in
Table 1, entries 5-15. Introduction of a t-Bu group at
the 4′-position of the aryl moiety (5d vs 7d , 6d vs 8d )
led to some decrease of the catalytic activity, but the
molecular weight and Mw/ Mn of the polyethylene formed
were similar. Interestingly, introduction of a 2-tolyl
group of the aryl group of the isocyanide in 5d caused
a dramatic decrease of the catalytic activity (entry 13,
using 9d ), whereas that of a 2,6-xylyl derivative (10d )
completely inhibited the reaction. Similarly, 2,6-dixylyl-
substituted derivative 11d showed no catalytic activity.
There is a striking difference in the molecular structure
of 10d (Figure 2) from that of 5d : the two methyl groups
in the ortho-aryl group prohibit the rotation, which may
be related to the inhibition mechanism by the methyl
groups at the 2- or 2,6-positions described above.The
above clearly showed that the polymerization behavior
is very sensitive to the ligand structure of Ni(II) iso-
cyanide complexes; in particular, 2- and 2,6-substituents
of the aryl group in NiBr2(CNAr)2 play key roles in both
catalyst efficiency and the molecular weight control of
the polyethylene formed. Use of alkyl isocyanides or
introduction of certain aryl substituents to the aryl
isocyanides inhibited the polymerization. These features
F igu r e 1. Molecular structure of 5d in the crystal (el-
lipsoids represent 50% probability; hydrogen atoms are
omitted for clarity). Selected bond length (Å), angles (deg),
and dihedral angles (deg): Ni1-C1 ) 1.846(2), C1-N1 )
1.141(3), Ni1-Br1 ) 2.2978(3), C1-Ni1-Br1 ) 90.4(1),
N1-C1-Ni1 ) 178.6(3), C1Ni1-C1* ) 179.97, Br1-Ni1-
C2-C3 ) -68.0, C2-C3-C8-C9 ) 49.2(4).
Scheme 1. A typical example is described in the Experi-
mental Section, and details are summarized in the
Supporting Information.
It was assigned from IR spectra in the literature16
that nickel isocyanide complexes, NiX2(CNR)2, generally
have a square-planar geometry with trans-configuration
of two isocyanide ligands, which can be adopted to nickel
complexes 1d -11d showing a single νC≡N absorption at
2190-2202 cm-1. The assigned structure is supported
by X-ray crystallographic analysis of one of the com-
pounds, 5d , of which the ORTEP drawing is illustrated
in Figure 1. Two bromine atoms and two carbons in the
isocyanide ligands are bonded to the nickel center with
bond distances of 2.2978(3) Å (Ni1-Br1) and 1.846(2)
Å (Ni1-C1), respectively. The CtN distances are 1.141-
(3) Å, which is similar to those of Pt(II), Pd(II), and Ni-
(0) complexes, trans-[PdI2(4-CN-3-C2H5C6H3CN)2] [Pd-
C ) 1.941(6) Å, CtN ) 1.150(7) Å],16a trans-[PtI2(CN-
C6H2-2,6-i-Pr2-4-Br)2] [Pt-C ) 1.946(6) Å, CtN )
1.146(8) Å],16b and [Ni(4-Br-2,6-Me2C6H3NC)4HgI2]2 [Ni-
C ) 1.936(19)-1.884(21) Å, CtN ) 1.145(26)-1.195-
(26) Å].16c 1H and 13C NMR data of nickel isocyanide
complexes, 1d -11d , are consistent with those deduced
from trans-NiX2(CNR)2 as described in the Experimen-
tal Section.
Studies on the polymerization of ethylene were car-
ried out in a 100 mL stainless steel autoclave in the
presence of MAO (Al/Ni ratio ) 100/1) as the cocatalyst
(Pethylene ) 0.8 MPa). Our initial examinations using 2,6-
dialkylphenylisocyanide as the ligand led to successful
polymerization of ethylene as shown in entries 1-3.
Although the activity was low (1-3 g/mmol Ni‚h), these
complexes act as polymerization catalysts; this is ap-
parent in comparison with the complete lack of activity
of NiBr2(CNR)2 (R ) t-Bu, cyclohexyl) under the condi-
tions used. An interesting observation of these poly-
merizations is the properties of polyethylene formed, in
which increase in the steric bulkiness of the ortho-
substituents of the phenylisocyanide ligands tended to
give a polymer with higher molecular weight and many
methyl branches (entries 1-3). In sharp contrast to the
fact that polymerization with the diisopropyl derivative
3d gave polyethylene with Mw ) 960 000, use of 4d as
the catalyst afforded polyethylene with magnitudes of
smaller molecular weight with somewhat higher cata-
(17) Galland, G. B.; de Souza, R. F.; Mauler, R. S.; Nunes, F. F.
Macromolecules 1999, 32, 1620.

Nickel(II) Isocyanide Complexes
Organometallics, Vol. 23, No. 16, 2004 3979
Ta ble 1. P olym er iza tion of Eth ylen ea
complex (amount
activity
branchb
entry
of catalyst)
yield (g)
(g/mmol‚h)
Mw
Mw/Mn
Mv
Tm (°C)
(1/1000C)
1
2
3
4
1d (100)
2d (100)
3d (100)
4d (100)
5d (10)
5d (1)
6d (100)
6d (10)
7d (10)
7d (10)
7d (1)
8d
0.181
0.192
0.088
0.353
2.23
0.633
0.746
0.466
0.80
1.98
0.267
0.344
0.210
0
1.81
1.92
0.88
3.53
223
200 000
580 000
960 000
4200
2.1
2.3
3.2
2.3
1.8
180 000
118.1
107.8
78.8
128.0
120.8
13.7
15.7
41.3
5.1
310 000
5
2200
5.5
6c
7
633
7.46
46.6
80.0
198
N.D.
2900
N.D.
2.4
6 100 000
132.5
128.9
(<5)
8
9
1.3
10c
11c
12
13
14
15
267
34.4
21.0
N.R.
N.R.
5 620 000
132.0
(<5)
9d
10d
11d
3000
3.1
0
a
All reactions were carried out in a 100 mL stainless steel autoclave in the presence of MAO (Al/Ni ) 100/1 unless otherwise noted)
at room temperature for 1 h. Ethylene (0.8 MPa) was applied. Type and amounts of branching were determined by 13C NMR according
b
to the assignment reported by Galland and co-workers.17 c The Al/Ni ratio was 1000/1.
and benzene-d6 were distilled from benzophenone ketyl and
stored under an argon atmosphere. Other reagents and
solvents were used as received. The 1H NMR spectra were
taken with a J EOL Lambda 400 or 600 spectrometer. Chemical
shifts were recorded in ppm from the internal standard (1H,
13C: solvent). IR spectra were recorded in cm-1 on a J ASCO
FT/IR-550 spectrometer. Molecular weights of the formed
polyethylene were deterimined by gel permeation chromatog-
raphy (TOSOH HLC-8121GPC/HT) using o-dichlorobenzene
as a solvent at 140 °C. The intrinsic viscosity [η] measurements
were carried out on an Automatic Viscometer (Shibayama
Scientific Co., Ltd. SS-201H-2T) in o-dichlorobenzene at 135
°C. Viscosity average molecular weights (Mv) of the formed
polyethylene were calculated by the following equation: [η] )
4.77 × 10-4Mv0.7. Transition melting temperatures of the
F igu r e 2. Molecular structure of 10d in the crystal
(ellipsoids represent 50% probability; hydrogen atoms are
omitted for clarity). Selected bond length (Å), angles (deg),
and dihedral angles (deg): Ni1-C1 ) 1.843(3), C1-N1 )
1.145(4), Ni1-Br1 ) 2.2857(4), C1-Ni1-Br1 ) 89.96(8),
N1-C1-Ni1 ) 178.6(3), C1-Ni1-C16 ) 176.8(1), Br1-
Ni1-C2-C7 ) 37.3, C2-C7-C8-C13 ) -72.3(4).
formed polyethylene were determined by differential scanning
calorimetory (Seiko DSC-200) at a heating rate of 10 °C/min.
Analysis of type and amounts of branching of the polymer
obtained was carried out by 13C NMR according to the
assignment in the literature.17 As a representative example,
an actual 13C NMR chart of polyethylene formed by the
experiment shown in Table 1, entry 1, is shown in the
Supporting Information (p S-23).
as well as the relatively narrow molecular weight
distribution strongly suggest that a single molecular
catalyst species is produced by the reaction of NiBr2-
(CNAr)2 with MAO. Further studies including a search
for more active catalysts as well as elucidation of
mechanism18 are in progress in our laboratory.
Syn th esis of 2-Ar yla n ilin es a n d 2,6-Dia r yla n ilin es. A
typical procedure is as follows: In a 300 mL flask were placed
2,6-dibromoaniline (25.3 mmol, 6.35 g), Pd(PPh3)4 (4.0 mmol,
4.62 g), and toluene (350 mL). To this flask were added an
ethanol solution of PhB(OH)2 (100 mL, 0.76 M, 76 mmol) and
an aqueous solution of Na2CO3 (200 mL, 1.9 M, 379 mmol).
The mixture was stirred at 80 °C for 3 days and then poured
into water. Organic products were extracted with ether. The
combined extracts were washed with water, dried over MgSO4,
and concentrated. The residue was purified by column chro-
matograpy (silica gel) eluted with ether to give 2,6-diphenyl-
aniline (6a ) in 88% yield (5.47 g). 6a : mp 71.5 °C. 1H NMR
(395 MHz, CDCl3): δ 7.54 (d, J ) 8.0 Hz, 4H, Ar), 7.48 (dd, J
) 8.0 Hz, 4H, Ar), 7.38 (t, J ) 7.3 Hz, 2H, Ar), 7.16 (d, J ) 7.5
Hz, 2H, Ar), 6.92 (t, J ) 7.5 Hz, 1H, Ar), 3.75 (br, 2H, NH2).
13C NMR (99 MHz, CDCl3): δ140.01, 141.00, 130.02, 129.58,
129.10, 128.18, 127.51, 118.40. IR: νN-H 3398, 3376, 1603.
HRMS: calcd 245.1204, found 245.1207. Anal. Calcd for
Exp er im en ta l Section
Gen er a l P r oced u r es. All experiments were carried out
under an argon atmosphere using standard Schlenk tech-
niques. Diethyl ether, THF, benzene, toluene, heptane, hexane,
(18) Although further detailed investigation to detect the reactive
catalyst species should be awaited, it seems worthwhile to point out
that there are two possibilities for the net catalyst species: One is the
case that the isocyanide behaves as a unique ligand to produce the
catalytic species. The cationic species, cis-(ArNC)2NiMe+, is its can-
didate, and MAO promotes trans- to cis-isomerization and methylation
of trans-(ArNC)2NiBr2 followed by generation of cationic species. The
other is the case that MAO-promoted oligomerization of isocyanides
on the nickel produces new nickel species. The paper reporting that
(Me3P)2Ni(R)X reacted with t-BuNC to give a metallacyclic compound
may indicate the involvement of oligomerization of isocyanides on the
nickel atom for the production of net catalyst species.19 We have
recently found that metallacyclic compounds analogous to that reported
in ref 19 are a good catalyst for ethylene polymerization in the presence
of MAO (Tanabiki, M.; Matsubara, K.; Motoyama, Y.; Nagashima, H.,
manuscript in preparation); this supports the mechanism involving
oligomerization of isocyanides on the nickel atom.
C
18H15N: C, 88.13; H, 6.16; N, 5.71. Found: C, 87.87; H, 6.23;
N, 5.75. In a similar fashion, a coupling reaction of other
arylboronic acids with 2-bromoaniline or 2,6-dibromoaniline
affords the corresponding aniline derivatives in 70-95% yield.
Spectral data are described in the Supporting Information.
Syn th esis of 2-Ar ylp h en yl Isocya n id es a n d 2,6-Dia r -
ylp h en yl Isocya n id es. A typical procedure is as follows: A
mixture of aniline (10 mmol), formic acid (130 mmol, 5.0 mL,
6.1 g), and toluene (50 mL) was heated under reflux. During

3980 Organometallics, Vol. 23, No. 16, 2004
Tanabiki et al.
Ch a r t 1
the reaction, formed water was removed from the reaction
mixture by a Dean-Stark apparatus. After 24 h, the reaction
mixture was evaporated to dryness, and the resulting white
solids were washed with ether to remove excess formic acid
and with hexane to get rid of trace amounts of aniline. Then,
the resulting solid was dried in vacuo at room temperature.
The crude product was used for the next step without further
Anal. Calcd for C54H58Br2N2Ni: C, 62.59; H, 3.59; N, 3.84.
Found: C, 62.52; H, 3.52; N, 3.81.
Dib r om ob is[2-(isocya n o-KC)-1,3-d im e t h ylb e n ze n e ]-
1
n ick el (1d ): mp 180 °C (dec). H NMR (400 MHz, CDCl3): δ
7.23 (t, 2H, J ) 7.59 Hz, para-H-Ar), 7.10 (d, 4H, J ) 7.59 Hz,
meta-H-Ar), 2.44 (s, 12H, ortho-Me-Ar). 13C NMR (100 MHz,
CDCl3): δ 136.44, 130.24, 128.00, and 125.59(Ar), 18.55 (Me-
Ar). IR: νCtN 2198. Anal. Calcd for C18H18Br2N2Ni: C, 44.96;
H, 3.77; N, 5.83. Found: C, 44.95; H, 3.79; N, 5.81.
1
purification. 6b: mp 175 °C. H NMR (395 MHz, CDCl3), two
isomers: δ 7.85 (d, J ) 0.97 Hz) and 7.78 (d, J ) 11.6 Hz)
(1H, CHO), 7.36-7.47 (m, 13H, Ar), 6.76 (d, J ) 11. 6 Hz) and
6.62 (bs) (1H, NH). 13C NMR (99 MHz, CDCl3): δ 164.47,
159.91, 140.75, 139.52, 138.47, 136.90, 130.67, 130.60, 130.01,
129.35, 129.01, 128.81, 128.26, 127.92, 127.80, 127.44, 126.54.
IR: νN-H ) 3233, νCdO ) 1653. HRMS: calcd 273.1154, found
273.1154. Anal. Calcd for C19H15NO: C, 83.49; H, 5.53; N, 5.12.
Found: C, 83.29; H, 5.57; N, 5.06. The formanilide prepared
by the above procedure (1.0 mmol) and diisopropylamine (350
mg, 3.5 mmol) were dissolved in CH2Cl2 (3.0 mL). The mixture
was cooled to 0 °C, and POCl3 (1.1 mmol) was added dropwise.
After stirring at 0 °C for 2 h, the solution was treated with
Na2CO3 (0.5 g) dissolved in H2O (3.0 mL) at a rate so that the
temperature was maintained at 25-30 °C. The mixture was
stirred for 12 h at room temperature. The organic layer was
separated, and the aqueous layer was extracted with CH2Cl2
three times. The organic layer and the extracts combined were
washed with Et2O, dried over MgSO4, and evaporated to
dryness. In all of the reactions, the desired product was
obtained as a single product (no byproduct was observed in
NMR and IR spectroscopy), which can be used in the next step
without further purification. The analytically pure product can
be obtained by recrystallization from ether and hexane. 6c:
Dibr om obis[2-(isocya n o-KC)-1,3-d ieth ylben zen e]n ick -
1
el (2d ): mp 193 °C (dec). H NMR (400 MHz, CDCl3): δ 7.31
(t, 2H, J ) 7.99 Hz, para-H-Ar), 7.12 (d, 4H, J ) 7.99 Hz, meta-
H-Ar), 2.79 (q, 8H, J ) 7.59 Hz, CH2-Et), 1.27 (t, 12H, J )
7.59 Hz, CH3-Et). 13C NMR (100 MHz, CDCl3): δ 142.36,
130.69, 126.51, and 124.19 (Ar), 25.40 (CH2-CH3) 14.22 (CH2-
CH3). IR: νCtN 2194. Anal. Calcd for C22H26Br2N2Ni: C, 49.21;
H, 4.88; N, 5.22. Found: C, 49.25; H, 4.89; N, 5.21.
Dibr om obis[2-(isocya n o-KC)-1,3-d iisop r op ylben zen e]-
1
n ick el (3d ): mp 224 °C (dec). H NMR (400 MHz, CDCl3): δ
7.38 (t, 2H, J ) 7.99 Hz, para-Ar), 7.18 (d, 4H, J ) 7.99 Hz,
meta-Ar), 3.35 (sept, 4H, J ) 6.79 Hz, CH of iPr), 1.28 (d, 24H,
J ) 6.79 Hz, Me of iPr). 13C NMR (100 MHz, CDCl3): δ 146.61,
130.88, 134.55, 123.53 (Ar), 29.43 (CHMe2), 22.73 (CHMe2).
IR: νCtN 2192. Anal. Calcd for C26H34Br2N2Ni: C, 52.66; H,
5.78; N, 4.72. Found: C, 52.66; H, 5.75; N, 4.71.
Dibr om obis[2-(isocya n o-KC)-1-isop r op ylben zen e]n ick -
el (4d ): mp 146 °C. 1H NMR (400 MHz, CDCl3): δ 7.45-7.41
(m, 6H, Ar), 7.26-7.22 (m, 2H, Ar), 3.35 (sept, 2H, J ) 6.79
Hz, CH of iPr), 1.29 (d, 12H, J ) 6.79 Hz, Me of iPr). 13C NMR
(100 MHz, CDCl3): δ 146.32, 131.20, 127.07, 126.70, 126.47,
and 126.61 (Ar), 29.28 (CHMe2), 22.65 (CHMe2). IR: νCtN 2190.
Anal. Calcd for C20H22Br2 N2Ni: C, 47.20; H, 4.36; N, 5.50.
Found: C, 47.63; H, 4.39; N, 5.56.
Dibr om obis[2-(isocya n o-KC)-1,1′-bip h en yl]n ick el (5d ):
mp 202 °C (dec). 1H NMR (395 MHz, CDCl3): δ 7.50-7.40 (m,
18H, Ar). 13C NMR (99 MHz, CDCl3): δ 139.20, 135.51, 131.05,
130.63, 129.04, 128.97, 128.78, 128.13, 128.01, 124.07. IR:
CtN2202. Anal. Calcd for C54H58Br2N2Ni: C, 54.13; H, 3.14;
N, 4.86. Found: C, 54.08; H, 3.15; N, 4.81.
1
mp 175 °C. H NMR (395 MHz, CDCl3): δ 7.37-7.56 (m, 13H,
Ar). 13C NMR (99 MHz, CDCl3): δ 169.23, 140.01, 137.56,
129.48, 129.34, 129.11, 129.02, 128.50, 128.32. IR: νCtN 2121.
HRMS: calcd 256.1126, found 256.1125.
In a similar fashion, 2-substituted phenylisocyanides and
2,6-disubstituted phenylisocyanides were synthesized via the
corresponding formanilides. Spectral data of the formanilides
and isocyanides synthesized are described in the Supporting
Information.
ν
Dib r om ob is[2-(isocya n o-KC)-1,3-d ip h e n ylb e n ze n e ]-
1
Syn th esis of Ni(II) Isocya n id e Com p lexes. A typical
example is given below. A solution of the isocyanide 6c (216
mg, 0.84 mmol) dissolved in CH2Cl2 (3.0 mL) synthesized by
the above procedure was added to a suspension of (1,2-
dimethoxyethane)NiBr2 (123 mg, 0.4 mmol) in CH2Cl2 (7.0
mL), and the mixture was stirred for 24 h at room tempera-
ture. The resulting suspension was filtered through a short
pad of Celite. The resulting dark brown filtrate was concen-
trated in vacuo, and the residue was washed with Et2O.
Recrystallization of this crude product from dichloromethane-
hexane gave the desired complex 6d in 83% yield (232 mg).
With similar procedures, nickel complexes 1d -5d and 7d -
11d were synthesized in 54-98% yield.
n ick el (6d ): mp 203 °C (dec). H NMR (395 MHz, CDCl3): δ
7.48-7.41 (m, 26H, Ar). 13C NMR (99 MHz, CDCl3): δ 140.42,
136.02, 130.39, 129.49, 129.28, 128.91, 128.65, 122.31. IR: νCt
2190. Anal. Calcd for C54H58Br2N2Ni: C, 62.59; H, 3.59; N,
3.84. Found: C, 62.52; H, 3.52; N, 3.84.
N
Dib r om ob is[2-(isocya n o-KC)-4′-t er t -b u t h ylb ip h en yl]-
n ick el (7d ): mp 241 °C (dec). 1H NMR (395 MHz, CDCl3):
δ7.34-7.52 (m, Ar, 16H), 1.38 (s, t-Bu, 18H). 13C NMR (99
MHz, CDCl3): δ151.76, 139.16, 132.63, 130.94, 130.54, 128.71,
128.14, 127.85, 125.98, 125.19, 34.71, 31.30. IR: νCtN 2197.
Anal. Calcd for C34H34Br2N2Ni: C, 59.26; H, 4.97; N, 4.07.
Found: C, 58.87; H, 5.00; N, 4.01.
Dibr om obis[2-(isocyan o-KC)-1,3-bis(4-ter t-bu tylph en yl)-
1
Dib r om ob is[2-(isocya n o-KC)-1,3-d ip h e n ylb e n ze n e ]-
ben zen e]n ick el (8d ): mp 255 °C (dec). H NMR (395 MHz,
1
n ick el (6d ): mp 203 °C (dec). H NMR (395 MHz, CDCl3): δ
CDCl3): δ 7.35-7.51 (m, 22H, Ar), 1.39 (s, t-Bu, 36H). 13C NMR
(99 MHz, CDCl3): δ 151.43, 145.25, 140.44, 133.25, 130.16,
129.37, 128.95, 125.91, 34.68, 31.35. IR: νCtN 2172. Anal. Calcd
7.49 (bs, 26H, Ar). 13C NMR (99 MHz, CDCl3): δ 140.42, 136.02,
130.39, 129.49, 129.28, 128.91, 128.65, 122.31. IR: νCtN 2190.

Nickel(II) Isocyanide Complexes
Organometallics, Vol. 23, No. 16, 2004 3981
Ta ble 2. X-r a y Cr ysta llogr a p h ic Da ta for 5d a n d
10d
for C54H58Br2 N2Ni: C, 68.02; H, 6.13. N, 2.94. Found: C, 67.41;
H, 6.13; N, 2.93.
Dibr om obis[2-(isocya n o-KC)-2′-m eth yl-1,1′-bip h en yl]-
5d
10d
1
n ick el (9d ): mp 180 °C (dec). H NMR (395 MHz, CDCl3): δ
empirical formula
fw
C
26H18N2Br2Ni
C30H26Br2N2Ni
633.06
123(1)
0.71075
monoclinic
P21/n
12.08(2) Å
14.76(3)
16.46(3)
90
7.19-7.23 (m, 6H, Ar), 7.00-6.96 (m, 2H, Ar), 6.82-6.77 (m,
6H, Ar), 6.66-6.61 (m, 2H, Ar), 2.13 (s, 6H, CH3). 13C NMR
(99 MHz, CDCl3): δ 139.77, 135.87, 135.41, 131.00, 130.64,
130.62, 129.43, 128.87, 128.18, 127.08, 126.06 and 125.31 (Ar),
20.60 (Me). IR: νCtN 2201. Anal. Calcd for C28H22Br2 N2Ni:
C, 55.59; H, 3.67; N, 4.63. Found: C, 55.57; H, 3.68; N, 4.62.
Dibr om obis[2-(isocya n o-KC)-2′,6′-d im eth yl-1,1′-bip h e-
n yl]n ick el (10d ): mp 206 °C (dec). 1H NMR (395 MHz,
CDCl3): δ 7.52-7.38 (m, 3H, Ar), 7.25-7.13 (m, 4H, Ar), 1.97
(s, 6H, CH3). 13C NMR (99 MHz, CDCl3): δ 139.18, 135.79,
135.02, 130.92, 130.83, 128.55, 128.14, 127.81, 127.05, 125.42
(Ar), 20.27. IR: νCtN 2198. Anal. Calcd for C30H26Br2 N2Ni: C,
56.92; H, 4.14; N, 4.43. Found: C, 56.65; H, 4.20; N, 4.46.
Dibr om obis[2-(isocya n o-KC)-1,3-bis(2,6-d im eth ylp h e-
n yl)ben zen e]n ick el (11d ): mp 262 °C (dec). 1H NMR (395
MHz, CDCl3): δ 7.52 (m, 2H, Ar), 7.25 (m, 16H, Ar), 1.98 (s,
24H, CH3). 13C NMR (99 MHz, CDCl3): δ 139.64, 135.68,
135.47, 130.50, 129.35, 128.39, 127.87 and 127.41 (Ar), 20.34
(Me). IR: νCtN 2195. Anal. Calcd for C46H42Br2 N2Ni: C, 65.67;
H, 5.03; N, 3.33. Found: C, 65.69; H, 5.03; N, 3.34.
Eth ylen e P olym er iza tion . In a typical example, toluene
(50 mL) and MAO (1.0 mmol, 0.42 mL in 7.5 wt % toluene
solution) were measured into a 100 mL Schlenk tube, and the
mixture was stirred for 15 min. The nickel complex (10 µmol)
prepared by the method described above was added, and the
solution was stirred for 1 h. The resulting catalyst/cocatalyst
solution was loaded into a 100 mL stainless steel autoclave,
and ethylene was introduced (0.8 MPa) at room temperature.
A continuous supply of ethylene kept the gas pressure at 0.8
MPa during the polymerization. The polymerization was
terminated by the release of ethylene and subsequent addition
of methanol (10 mL). The product was added to a mixture of
methanol (200 mL) and concentrated HCl (12 mL) to remove
aluminum compounds. Polyethylene precipitated was isolated
by filtration, washed with methanol, and dried in vacuo for
12 h.
576.95
123(1)
0.71075
triclinic
P1h
temperature, K
wavelength, Å
cryst syst
space group
a, Å
8.588(5)
8.740(5)
9.090(4)
67.70(4)
73.47(4)
64.02(4)
561.7(5)
1
b, Å
c, Å
R, deg
â, deg
108.1(1)
90
2790(8)
4
γ, deg
V, Å3
Z
density(calcd), Mg/m3
abs coeff, cm-1
F(000)
1.705
44.47
286.00
1.507
35.88
1272
cryst size, mm
θ range for data
collection, deg
index ranges
0.40 × 0.25 × 0.08 0.40 × 0.40 × 0.10
3.0-30.0
3.0-30.0
-11 e h e 11;
-11 e k e 11;
-11 e l e 11
2552
2552 [R(int) )
0.053]
-15 e h e 15;
-19 e k e 18;
-19 e l e 21
6632
6632 [R(int) )
0.050]
no. of reflns collected
no. of indep reflns
no. of reflns obsd (>2σ) 2546
refinement method
6365
full-matrix least-
full-matrix least-
squares on F2
6365/0/343
squares on F2
no. of data/restraints/
params
2546/0/152
goodness-of-fit on F2
final R indices
[I>2σ(I)]
1.009
1.008
R1 ) 0.030
R1 ) 0.031
R indices (all data)
largest diff peak and
hole, e Å-3
wR2 ) 0.080
0.65 and -0.98
wR2 ) 0.059
0.80 and -0.76
tions and 152 variable parameters for 5d and on 6365 observed
reflections and 343 variable parameters for 10d . Neutral atom
scattering factors were taken from Cromer and Waber.23 All
calculations were performed using the CrystalStructure24,25
crystallographic software package. Details of final refinement
are summarized in Table 2, and the numbering schemes
employed are shown in Figures 1 and 2, which were drawn
with ORTEP with 50% probability ellipsoids.
X-r a y Str u ctu r e Deter m in a tion a n d Deta ils of Refin e-
m en t. X-ray-quality crystals of 5d and 10d were grown from
a
mixture of CH2Cl2 and hexane and mounted in glass
capillaries. All measurements were made on a Rigaku RAXIS
RAPID imaging plate area detector with graphite-monochro-
mated Mo KR radiation; λ ) 0.71075 Å. The data were collected
at 123(1) K using a ω scan technique to a maximum 2θ value
of 55°. The data were corrected for Lorentz and polarization
effects. The structure was solved by heavy-atom Patterson
methods20 for 5d and by direct methods21 for 10d , and
expanded using Fourier techniques.22 The non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were refined
using the riding model. The final cycle of full-matrix least-
squares refinement on F2 was based on 2546 observed reflec-
Ack n ow led gm en t. We appreciate the financial sup-
port provided by Grants-in-Aid for Scientific Research
from the Ministry of Education, Culture, Sports, and
Technology, J apan. A part of this study was supported
by CREST (J ST, J apan Science and Technology Coor-
poration).
Su p p or tin g In for m a tion Ava ila ble: Characterization of
6a -6c, 7a -7c, 8a -8c, 9a -9c, 10a -10c, and 11a -11c,
crystallographic data of 5d and 10d , and a 13C NMR chart of
polyethylene. This material is available free of charge via the
Internet at http://pubs.acs.org.
(19) Bochman, M.; Hawkins, I.; Sloan, M. P. J . Organomet. Chem.
1987, 332, 371.
(20) PATTY: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bos-
man, W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla,
C. The DIRDIF Program System; Technical Report of the Crystal-
lography Laboratory; University of Nijmegen: Nijmegen, The Neth-
erlands, 1992.
(21) Burla, M. C.; Camalli, M.; Carrozzini, B.; Cascarano, G. L.;
Giacovazzo, C.; Polidori, G.; Spagna, R. SIR92; 2003.
(22) DIRDIF99: Beurskens, P. T.; Admiraal, G.; Beurskens, G.;
Bosman, W. P.; de Gelder, R.; Israel, R.; Smits, J . M. M. The DIRDIF-
99 program system; Technical Report of the Crystallography Labora-
tory; University of Nijmegen: Nijmegen, The Netherlands, 1999.
OM0498394
(23) Cromer, D. T.; Waber, J . T. International Tables for X-ray
Crystallography; Kynoch Press: Birmingham, U.K., 1974; Vol. 4.
(24) CryatalStructure 3.5.1, Crystal Structure Analysis Package;
Rigaku and Rigaku/MSC: Tokyo and The Woodlands, 2003.
(25) Watkin, D. J .; Prout, C. K.; Carruthers, J . R.; Betteridge, P.
W. CRYSTALS Issue 10; Chemical Crystallography Laboratory: Ox-
ford, U.K., 1996.