Polymerization of aryl isocyanides by cyclopentadienylnickel-alkynyl complexes

Article abstract of DOI:10.1016/S0022-328X(98)00423-9

(η⁵-Cyclopentadienyl)nickel-alkynyl complexes, CpNi(PPh₃)C≡CR (R = Ph, H, CO₂Et), and -methyl complex effectively catalyze the polymerization of aryl isocyanides at room temperature. Double-insertion complexes of isocyanid

Full text of DOI:10.1016/S0022-328X(98)00423-9

Journal of Organometallic Chemistry 559 (1998) 91–96
Polymerization of aryl isocyanides by cyclopentadienylnickel–alkynyl
complexes
Fumie Takei, Shaopo Tung, Koichi Yanai, Kiyotaka Onitsuka, Shigetoshi Takahashi *
The Institute of Scientific and Industrial Research, Osaka Uni6ersity, Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
Received 28 October 1997; received in revised form 20 January 1998
Abstract
(p5-Cyclopentadienyl)nickel–alkynyl complexes, CpNi(PPh3)CꢀCR (R=Ph, H, CO2Et), and -methyl complex effectively
catalyze the polymerization of aryl isocyanides at room temperature. Double-insertion complexes of isocyanides are isolated and
characterized as an active intermediate of the polymerization, whose mechanism involving successive insertion of isocyanides into
nickel–carbon |-bonds is proposed. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Nickel acetylides; Cyclopentadienylnickel; Polymerization; Isocyanides; Multiple insertion
1. Introduction
cyanides and the polymerization proceeds via successive
and multiple insertion of isocyanides into a metal–car-
bon |-bond of the ethynediyl dinuclear complexes.
However, mononuclear palladium- and platinum–
alkynyl complexes did not exhibit a catalytic activity
for the polymerization of isocyanides although
mononuclear palladium–alkyl complexes are known to
be active for the polymerization of isocyanides [6]. Now
we have found mononuclear cyclopentadienylnickel–
alkynyl complexes to be active for the polymerization
of aryl isocyanides, and successfully isolated an active
intermediate in the initiation step of the polymerization.
It is well-known that nickel complexes such as
Ni(CO)4 [7] and NiX2 [8] complexes exhibit a high
activity for the polymerization of isocyanides, and re-
cently Novak and co-workers have found a living poly-
merization system with (p3-allyl)nickel catalysts and
applied the system to a stereoselective polymerization
of isocyanides [9]. We also attempted to find a new type
of nickel catalysts and tried to prepare the nickel
analog of v-ethynediyl dinuclear complexes [10], but
failed the preparation probably due to instability of
nickel complexes in the reaction conditions. About 30
years ago Yamazaki and Yamamoto reported the reac-
tion of cyclopentadienylnickel–alkyl and -aryl com-
In recent years polymerization reactions catalyzed by
transition metal complexes have attracted much atten-
tion in the fields of polymer science and organometallic
chemistry in terms of unique polymer synthesis and
mechanistic interest. Many reports on the design and
synthesis of active transition metal catalysts for poly-
merization of various monomers have appeared in the
literature in the last few decades [1]. Such representative
examples involve cyclopentadienyl-group 4 metal com-
plexes for olefin polymerization [2], ruthenium- and
tungsten–carbene complexes for ring-opening metathe-
sis polymerization [3] and cyclopentadienyl–lanthanide
complexes for vinyl polymerization [4]. In these systems
the role of metal catalysts as well as the polymerization
process have been well studied on the basis of
organometallic chemistry and in some cases active in-
termediates in the polymerization reactions have been
isolated and characterized.
We previously reported [5] that v-ethynediyl palla-
dium–palladium and palladium–platinum dinuclear
complexes catalyze the living polymerization of iso-
* Corresponding author. Fax: +81 6 8798459.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00423-9

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F. Takei et al. / Journal of Organometallic Chemistry 559 (1998) 91–96
plexes with alkyl isocyanides to yield isocyanide insertion
products [11]. For example, (p5-cyclopentadienyl)(triph-
enylphosphine)nickel–methyl reacted with cyclohexyl
isocyanide to give an insertion product, CpNi(CNC6
H11)C(CH3)ꢁNC6H11, but further insertion of cyclohexyl
isocyanide was not observed. Now, we have found that
the nickel–methyl complex undergoes multiple insertion
of aryl isocyanides and exhibit a catalytic activity for the
polymerization of p-butylphenyl and p-octylphenyl iso-
cyanide. We also found air-stable cyclopentadienyl-
nickel–alkynyl complexes to show a high activity for the
polymerization of aryl isocyanides. The latter may
provide the first example of mononuclear transition
metal alkynyls active for the polymerization of iso-
cyanides. We report here the catalysis of cyclopentadi-
enylnickel–alkynyl complexes in the polymerization of
aryl isocyanides, and the polymerization mechanism will
be discussed on the basis of stoichiometric reactions
between the nickel complexes and isocyanides.
istic of isocyanide polymers. However 3a is unable to
be characterized in details by NMR spectral analyses
because of its low solubility in solvents such as ben-
zene, THF and dichloromethane. In order to improve
the solubility of polymers, alkyl-substituted phenyl
isocyanides are used as a monomer. p-Butylphenyl-
(2d) and p-octylphenyl isocyanide (2e) were similarly
polymerized in the presence of 1 mol.% of 1a under
the same reaction conditions. Polymers 3d and 3e
thus obtained showed the typical absorption of
w(CꢁN) at 1650 cm−1 in the IR spectra, and were
identified by spectral analyses as they are soluble in
benzene, THF and dichloromethane. (See Section 3,
Experimental) The 13C-NMR spectrum of 3d showed
a broad signal due to CꢁN groups at 162.8 ppm.
p-Nitrophenyl isocyanide also gave polymer 3f in 40%
yield. The low yield is due to its low solubility which
causes precipitation of the polymer formed during the
reaction. 2,6-Dimethylphenyl isocyanide 2g did not
give polymeric products at all and the monomer was
recovered. Sterically bulky 2,6-dimethylphenyl group
presumably prevents successive insertion of the iso-
cyanide into the Ni–C bond. The results of iso-
cyanide polymerization are summarized in Table 1,
which reveals that complex 1a is active for the poly-
merization of a variety of aryl isocyanides, but inac-
2. Results and discussion
2.1. Polymerization of isocyanides
Isocyanides have an isoelectric structure with carbon
monoxide and both sometimes insert into a metal–car-
bon |-bond to form an imino or carbonyl group.
Transition metal–alkyl bonds often undergo isocyanide
insertion, in some cases multiple insertion [12], whereas
transition metal–alkynyl bonds are stable and resist
isocyanide insertion except few particular cases [13].
Since multiple and successive insertion of isocyanides
may lead to polymerization of isocyanides, transition
metal complexes containing M–C |-bonds have a poten-
tial to act as a catalyst (or initiator) for the polymeriza-
tion of isocyanides [5,6,14]. In an attempt to find effective
catalysts for isocyanide polymerization, we treated (p5-
cyclopentadienyl)nickel–phenylacetylide complex, Cp-
Ni(PPh3)CꢀCPh 1a, with 100 equivalents of m-benz-
ylaminocarbonylphenyl isocyanide 2a at room tempera-
ture in THF and found that polymerization occurred
smoothly to afford yellow polymer 3a (Mw=27600,
Mw/Mn=1.46) in 60% yield after usual work-up and
precipitation with methanol. Polymer 3a exhibits an
absorption of w(CꢁN) at 1650 cm−1 which is character-
tive
for
alkyl
isocyanides.
(p5-Cyclopentadi-
enyl)nickel–alkynyl complexes such as CpNi
(PPh3)CꢀCH 1b and CpNi(PPh3)CꢀCCOOEt 1c as
well as (p5-cyclopentadienyl)nickel-methyl 4 also ex-
hibited the catalytic activity towards the polymeriza-
tion of aryl isocyanides.
Interestingly, chiral isocyanide m-(−)-menthoxycar-
bonylphenyl isocyanide 2c yielded polymer 3c in 77%
yield which exhibits a large optical rotation power
[h]. Polyisocyanides have a 41 helical structure and
usually exist a 1:1 mixture of two conformational iso-
mers with right- and left-handed helices. Monomer 2c
bearing a (−)-menthyl group shows an optical rota-
tion power of −83°, while polymer 3c exhibits +
296° with the opposite sign to the monomer,
indicating that the large optical rotation power arises
from a helical chirality of 3c [15]. and that nickel
complex 1a is able to catalyze a screw-sense-selective
polymerization of 2c to give polymer 3c having sin-
gle-handed helix.
2.2. Stoichiometric reaction of isocyanides
In order to know the polymerization mechanism,
reactions of nickel catalysts with stoichiometric amounts
of isocyanides were investigated. On treatment of Cp-
Ni(PPh3)CꢀCPh 1a with three equivalents of m-
PhCH2NHCOC6H4NC 2a in dichloromethane at room
temperature, we obtained reddish-brown complex 5a in

F. Takei et al. / Journal of Organometallic Chemistry 559 (1998) 91–96
93
lapping with the absorption of the N–H group, in the
13C-NMR spectrum two signals due to CꢁN groups
appeared at 177.6 (CꢁN) and 156.6 ppm (CꢁN), and in
27% yield along with isocyanide oligomers and recov-
ered 1a. The FAB mass spectrum (m/z=697, M+1)
and elemental analysis suggested 5a to be a product
derived from an addition of two molecules of 2a to 1a
and an elimination of the triphenylphosphine ligand
from 1a. The IR spectrum of 5a exhibited an absorp-
tion at 2141 cm−1 due to v(CꢀC) which appeared at a
higher wave number than that of 1a (2098 cm−1).
Although the absorption attributable to a CꢁN group
was not assigned in the IR spectrum because of over-
1
addition the H-NMR spectrum clearly showed signals
due to the CH2 protons of the benzylamino groups at
4.35 and 4.62 ppm, suggesting the presence of two
kinds of CꢁNR groups in 5a. The IR and NMR spectra
indicated that 5a does not contain isocyanide ligands
coordinated the nickel atom. The proton signal of the
cyclopentadienyl group appeared at 5.30 ppm, and
carbon signals assignable to the CꢀC group at 98.84
and 121.49 ppm, while no peaks were observed in the
31P-NMR spectrum. These data indicate 5a to be a
double-insertion product in which two molecules of
isocyanide 2a successively insert into the Ni–C bond of
1a. Similarly the reaction of 1a with three equivalents
Table 1
Polymerizationa of isocyanides RNC catalyzed by CpNi(PPh3)CꢀCY
1 and CpNi(PPh3)CH3
4
Run
R
Catalystb Yield
Mw
of p-tolyl isocyanide 2b and m-(−)-menthoxycar-
bonylphenyl isocyanide 2c gave 5b and 5c, respectively.
Double-insertion product 5 thus obtained seems to be
an apparent 16-electron complex of divalent nickel and
coordinately unsaturated one (structure 5A). A molecu-
lar structure of 5B or 5C seems more likely because it
forms an 18-electron complex by coordination of the
imino nitrogen atom or the acetylene group. However,
complexes 5 showed a normal stretching frequency of
the CꢀC group around 2140 cm−1 in the IR spectra,
and we did not observe a shift to lower frequencies
suggesting an interaction of the CꢀC group with the
central nickel atom; that is, the terminal acetylenic
group to be free.
It is known that 4 and CpNi(PPh3)CꢀCPh react with
cyclohexyl isocyanide to give a single-insertion product
CpNi(CNC6H11)C(R)ꢁNC6H11 (R=Me or Ph) with re-
placement of the PPh3 ligand by the isocyanide [11].
However, the analogous form 5D is excluded for the
structure of 5 because the spectral data indicate the
presence of two kinds of imino groups and the absence
of a coordinated isocyanide ligand in 5 as mentioned
above. Then, we added excess amounts of PPh3 to a
solution of 5a in THF, but 5a was recovered intact.
a Conditions: 1 mol.% of 1 in THF at room temperature.
b 1a: Y=Ph, 1b: Y=H, Y=CO2Et.
c Not determined due to its low solubility in THF.
d 2 mol.% of 1 in THF at 40°C.

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F. Takei et al. / Journal of Organometallic Chemistry 559 (1998) 91–96
and Mw/Mn=1.94, addition of 50 equivalents of 3,5-
dipropoxycarbonylphenyl isocyanide as second
a
monomer produced a co-polymer having Mw=71000
and Mw/Mn=2.46. The increase in the molecular
weight of the resulting polymer suggests a living na-
ture of the present system, however the rather large
polydispersity index (Mw/Mn) means that the present
polymerization is not a real living one. Then, in an
attempt to stabilize the living nickel catalyst and to
improve the polymerization reaction, triphenylphos-
phine was added to the polymerization system ini-
tiated with complex 1a. Addition of 10 equivalents of
PPh3, however, did not affect significantly the poly-
merization of isocyanide 2a and gave a polymer of
Mw=26000, Mw/Mn=1.56. Almost no effect of the
additional phosphine on the polymerization (cf. Table
1, run 1) is consistent with the proposed mechanism,
in which an isocyanide monomer interacts with the
active nickel complexes much more strongly than
triphenylphos-phine.
Scheme 1.
Addition of isocyanides to 5 caused further insertion
of isocyanides leading to the polymerization (vide in-
fra). On the basis of these facts, we tentatively pro-
pose molecular structure 5B which involves an
interaction between the imino nitrogen atom and the
nickel one, although we have not yet obtained evi-
dence for confirming such the interaction from the
spectral analyses.
An experiment by monitoring with gel permeation
chromatography demonstrated that the reaction of 1a
with one equivalent of isocyanide 2a at room temper-
ature in dichloromethane gave double-insertion
product 5a along with recovered complex 1a, but the
formation of a single-insertion product was not de-
tected. Probably a second monomer reacts with a sin-
gle-insertion complex much faster than the first one
with 1a, and the same phenomenon has been ob-
served for the reaction of a v-ethynediyl dipalladium
complex with phenyl isocyanide [5].
3. Experimental
All reactions were carried out under an atmosphere
of argon, but the work-up was performed in air. H-
1
and 13C-NMR were recorded in CDCl3 on a JEOL
EX-270 (270 MHz) and JEOL JNM-LA400 (400
MHz) spectrometer using SiMe4 as an internal stan-
dard, and 31P-NMR (in CDCl3) spectra on a JEOL
JNM-LA400 (400 MHz) spectrometer against an ex-
ternal 85% H3PO4 reference. Chemical shifts are given
in ppm. IR and mass spectra were taken on a
Perkin–Elmer System 2000 FT-IR and JEOL JMS-
600H instrument, respectively. Elemental analyses
were performed by the Material Analysis Center,
ISIR, Osaka University. Molecular weight measure-
ments were carried out by a Shimazu LC-6AD liquid
chromatograph using columns of Shimazu GPC-805,
-804 and -8025 with polystyrene standards.
2.3. Polymerization mechanism
We examined the reactivity of double-insertion
complexes 5 for isocyanides and found that they can
initiate the polymerization of isocyanides. When 5a
was treated with 100 equivalents of isocyanide 2a in
THF at room temperature, polymerization reaction
smoothly occurred to give a yellow polymer with Mw
of 37000 and Mw/Mn of 2.18 in 60% yield (Table 1,
run 12). The almost same catalytic activity of 5a as
1a unambiguously indicates 5a to be an active inter-
mediate at the initial stage of the polymerization.
Other double-insertion complexes 5b and 5c also ef-
fectively initiate the polymerization of isocyanides.
Thus, we propose the polymerization mechanism in-
volving successive insertion of isocyanides into the
nickel–carbon bond. (Scheme 1) The mechanism may
predict a living nature of the polymerization if the
Ni–imino complexes are stable during the propaga-
tion step. Actually, after complete reaction of 1a with
50 equivalents of 2c, of which the GPC analysis
showed the formation of polymer 3c with Mw=57000
3.1. Materials
Aryl and alkyl isocyanides were prepared according
to the literature methods [16]. (p5-Cyclopentadi-
enyl)methyl(triphenylphosphine)nickel 4 was prepared
from the reaction of CpNi(PPh3)Cl with MeMgI by
the literature method [17].
3.1.1. Synthesis of CpNi(PPh3)CꢀCPh (1a) [18]
To a solution of PhCꢀCH (102 mg, 1 mmol) in 15 ml
of a 1/2 mixture of Et2O and Et3N was added a
solution of CpNi(PPh3)Cl (243 mg, 1 mmol) in 25 ml of
Et2O. After addition of a CuCl catalyst (5 mg) the
reaction mixture was stirred for 1.5 h at room tempera-
ture. The solvent was evaporated and the residue was

F. Takei et al. / Journal of Organometallic Chemistry 559 (1998) 91–96
95
chromatographed on alumina with benzene. The frac-
tion of a green band was collected, and the solvent
was removed to give green crystals 1a. (368 mg 82%)
13C-NMR: (67.8 MHz, CDCl3) l 134.44–124.53 (m,
ArC), 119.73 (s, CꢀCNi), 85.77 (d JP–C=49 Hz,
Polymer 3b: yield: 70%; Anal. Calcd for (C8H7N)n:
C, 82.02; H, 6.02; N, 11.96%; Found: C, 81.80; H,
5.81; N, 11.69%; IR (KBr pellet): w(CꢁN) 1650 cm−1
.
Polymer 3c: yield: 77%; 13C-NMR: (100 MHz,
CDCl3) l 164.4 (br, ArCOOC), 160.7 (br, CN), 150.8
(br, ArC), 129.1 (br, ArC), 118.6 (br, ArC), 74.7 (br,
CH2), 47.3, 41.0, 34.4, 31.5, 31.0, 26.5, 23.7, 22.1,
20.8, 17.1, 16.5 (br, menthyl–C); Anal. Calcd for
(C18H23O2N)n: C, 75.76; H, 8.12; N, 4.91%; Found: C,
75.71; H, 8.00; N, 4.71%; IR (KBr pellet): w(CꢁN)
1650 cm−1; [h]2D0=296° (CHCl3, c=0.05).
1
CꢀCNi), 92.58 (s, CpC); H-NMR: (270 MHz, CDCl3)
l 7.78–7.70 (m, 6H, PPh3–H), 7.42–7.25 (m, 9H,
PPh3–H)), 6.93–6.88 (m, 3H, ꢀCPh–H)), 6.65–6.62
(m, 2H, ꢀCPh–H)), 5.25 (s, 5H, CpH); 31P-NMR:
(162 MHz, CDCl3) l 41.3 (s, PPh3): IR (KBr pellet):
w(CꢀC) 2098 cm−1; Anal. Calcd for C31H25PNi: C,
76.42; H, 5.17; P, 6.36%; Found: C, 76.19; H, 5.22; P,
6.12%; m.p. 131–132°C (dec.).
Polymer 3d: yield: 67%; 13C-NMR: (100 MHz,
CDCl3) l 1162.8 (br, CN), 146.2 (br, ArC) 138.0 (br,
ArC), 127.7 (br, ArC), 118.5(br, ArC), 35.5 (br, CH2),
33.7 (br, CH2), 22.3(br, CH2), 14.0 (br, CH2); Anal.
Calcd for (C11H13N)n: C, 83,03; H, 8.17; N, 8.80%;
Found: C, 81.98; H, 7.76; N, 9.90%; IR (KBr pellet):
3.1.2. Synthesis of CpNi(PPh3)CꢀCY 1b and 1c
Alkynyl complexes CpNi(PPh3)CꢀCH 1b and Cp-
Ni(PPh3)CꢀCCO2Et 1c were similarly prepared in a
mixed solvent of diethyl ether and triethylamine.
1b: green crystals; yield 65%, m.p. 124–126°C (dec.);
w(CꢁN) 1650 cm−1
.
IR (KBr pellet): w(ꢀC–H) 3250, w(CꢀC) 1960 cm−1
;
Polymer 3e: yield: 73%; Anal. Calcd for
(C15H21N1)n: C, 83.67; H, 9.83; N, 6.50%; Found: C,
82.98; H, 9.58; N, 6.74%; IR (KBr pellet): w(CꢁN)
1H-NMR: (270 MHz, CDCl3) l 7.8–7.7 (m, 6H,
PPh3–H), 7.48–7.33 (m, 9H, PPh3–H), 5.18 (s, 5H,
CpH); 1.46 (d, JP–H=2.64 Hz, 1H, ꢀCH)
1650 cm−1
.
Polymer 3f: yield: 36%; IR (KBr pellet): w(CꢁN)
1c: green crystals; yield 65%, m.p. 62–64°C (dec.);
1H-NMR: (270 MHz, CDCl3) l 7.72–7.36 (m, 15H,
PPh3–H), 5.2 (s, 5H, CpH), 3.8 (q, J=7.26 Hz, 2H,
O–CH2–), 1.1 (t, J=7.26 Hz, 3H, O–C–CH3); IR:
w(CꢀC) 2090 cm−1, w(CꢁO) 1667 cm−1; Anal. Calcd
for C28H25O2PNi: C, 69.68; H, 5.18%; Found: C,
69.63; H, 5.19%.
1650, w(NO2) 1520, w(NO2) 1380 cm−1
.
3.3. Stoichiometric reactions of complexes with
isocyanides
3.3.1. Reaction of complex 1a with
m-benzylaminocarbonylphenyl isocyanide 2a
3.2. Polymerization of isocyanide
To a solution of m-benzylaminocarbonylphenyl iso-
cyanide 2a (354 mg, 1.5 mmol) in 15 ml of THF was
added a solution of complex 1a (243 mg, 0.5 mmol) in
10 ml of CH2Cl2. After stirred for 1.5 h under room
temperature, the solution was chromatographed on alu-
mina with CH2Cl2. After removing unreacted 1a and an
isocyanide oligomer, a mixture of CH2Cl2 /ethyl acetate
(19/1: v/v) was use as an eluent. The fraction of the
orange band was collected, and the solvent was evapo-
rated under reduced pressure. Addition of hexane (100
ml) gave a precipitate, which was washed with hexane
and dried in vacuum to afford reddish-brown powder
of 5a (95 mg, 27%).
3.2.1. Polymerization of m-benzylaminocarbonylphenyl
isocyanide 2a with catalyst 1a
To a solution of m-benzylaminocarbonylphenyl iso-
cyanide (354 mg, 1.5 mmol) in 10 ml of THF was
added a solution of CpNi(PPh3)C2Ph 1a (7.3 mg,
0.015 mmol) in 5 ml of THF. After stirred for 24 h at
room temperature, the solution was concentrated to
about 1 ml. Addition of methanol (100 ml) gave a
precipitate, which was collected, washed with
methanol, and dried in vacuum to afford yellow pow-
der of 3a (216 mg, 60%); Anal. Calcd for
(C15H12ON2)n: C, 76.25; H, 5.12; N, 11.86%; Found:
13C-NMR: (100 MHz, CDCl3) (ppm) l 177.64 (s,
CN), 167.96 (s, ArCOOC), 165.59 (s, ArCOOC),
156.59 (s, CN), 150.42 (s, ArC), 138.55–119.66 (m,
C, 76.07; H, 5.11; N, 11.93%. IR: w(CꢁN) 1650 cm−1
.
3.2.2. Polymerization of p-tolyl isocyanide 2b,
m-(−)-menthoxycarbonylphenyl isocyanide 2c,
p-n-buthylphenyl isocyanide 2d, p-n-octylphenyl
isocyanide 2e, or p-nitrophenyl isocyanide 2f with
catalyst 1a
The polymerizations of 2b–2f (1.5 mmol) were car-
ried out with 1a (0.015 mmol) in THF at room tem-
perature by the procedure similar to that for 2a to
give polymers 3b–3f.
1
ArC), 92.99 (s, CpC), 43.94 (s, CH2); H-NMR: (400
MHz, CDCl3) l 8.37 (s, 1H, NH), 7.94–7.13 (m, 23H,
ArH), 6.63 (s, 1H, NH), 5.30 (s, 5H, CpH), 4.62 (d,
2H, J=6 Hz, CH2), 4.35 (d, 2H, J=6 Hz, CH2); IR
(KBr pellet): w(CꢀC) 2146 cm−1
;
Anal. Calcd
for C43H34O2N4Ni: C, 74.05; H, 4.91; N, 8.03%;
Found: C, 73.89; H, 4.67; N, 7.99%; Mass: m/z 697
(M+1).

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F. Takei et al. / Journal of Organometallic Chemistry 559 (1998) 91–96
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3.3.2. Reaction of complex 1a with isocyanides 2a and
2c
Similarly the reaction of 1a with 3 equivalents of
p-tolyl isocyanide 2b and m-(−)-menthoxycar-
bonylphenyl isocyanide 2c gave complexes 5b and 5c,
respectively.
5b: reddish-brown oil: yield 32%; 13C-NMR: (100
MHz, CDCl3) l 173.83 (s, CN), 153.08 (s, CN), 149.62
(s, ArC), 139.18–120.37 (m, ArC) 92.57 (s, CpC),
1
21.34, 21.04 (s, CH3); H-NMR: (400 MHz, CDCl3) l
7.56–7.00 (m, 13H, ArH), 5.28 (s, 5H CpH), 2.35 (s,
3H, CH3), 2.33 (s, 3H, CH3); IR (KBr pellet): w(CꢀC)
2135, w(CꢁN) 1542 cm−1
.
5c: reddish-brown solid: yield 61%; 13C-NMR: (100
MHz, CDCl3) l 176.66 (s, CN), 166.0 7 (s, ArCOOC),
164.02 (s, ArCOOC), 155.45 (s, CN), 151.43 (s, ArC),
133.55–121.00 (m, ArC), 92.94 (s, CpC), 77.00, 76.51
(s, menthyl–C), 47.22, 47.03, 40.95, 40.76, 34.16, 34.07,
31.47, 31.32, 26.35, 26.26, 23.37, 22.54, 21.94, 20.76,
1
16.28 (s, menthyl–C); H-NMR: (400 MHz, CDCl3) l
8.02–7.27 (m,13H, ArH), 5.36 (s, 5H, CpH), 4.98–4.91
(m, 2H, menthyl–H)), 2.10–0.77 (m, 36H, menthyl–
H); IR (KBr pellet): w(CꢀC) 2135 cm−1; Anal. calcd
for C49H56O2N2Ni: C, 73.96; H, 7.09; N, 3.52%; Found:
C, 73,75; H, 7.09; N, 3.61%.
[10] (a) K. Onitsuka, H. Ogawa, T. Joh, S. Takahashi, Y. Ya-
mamoto, H. Yamazaki, J. Chem. Soc. Dalton Trans. (1991)
1531. (b) K. Onitsuka, T. Joh, S. Takahashi, Bull. Chem. Soc.
Jpn. 32 (1992) 851.
[11] Y. Yamamoto, H. Yamazaki, N. Hagihara, J. Organomet.
Chem. 18 (1969) 189.
Acknowledgements
[12] Y. Yamamoto, T. Tanase, T. Yanai, T. Asano, K. Kobayashi, J.
Organomet. Chem. 456 (1993) 287 and references therein.
[13] F.R. Lemke, R.M. Bullock, Organometallics 11 (1992) 4261.
[14] S. Otsuka, A. Nakamura, T. Yoshida, J. Am. Chem. Soc. 91
(1969) 7196.
[15] F. Takei, K. Yanai, K. Onitsuka, S. Takahashi, Angew. Chem.
Int. Ed. Engl. 35 (1996) 1554.
[16] R. Obrecht, R. Herrmann, I. Ugi, Synthesis (1985) 400.
[17] H. Yamazaki, T. Nishido, Y. Matsumoto, S. Sumida, N. Hagi-
hara, J. Organomet. Chem. 6 (1966) 86.
This work is supported by Grant-in-Aid for Scientific
Research on Priority Areas, ‘New Polymers and Their
Nano-Organized Systems’ (No. 277/08246103), from
The Ministry of Education, Science, Sports and
Culture.
[18] (a) K. Sonogashira, T. Yatake, Y. Tohda, S. Takahashi, N.
Hagihara, J. Chem. Soc. Chem. Commun. (1977) 291. (b) M.I.
Bruce, M.G. Humphrey, J.G. Matisons, S.K. Roy, A.G. Swin-
cer, Aust. J. Chem. 37 (1984) 1955.
References
[1] See, for example, (a) J.C. Salamone (Ed.), Polymeric Material
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.