Preparation of chelate bis(imine)nickel allyl systems by reaction of their corresponding butadiene complexes with electrophiles

Article abstract of DOI:10.1016/S0022-328X(03)00699-5

The chelate 1,2-bis(imine)nickel(butadiene) complex 4a (chelate ligand derived from condensation of biacetyl with 2,6-diisopropylaniline) adds the strong Lewis acid B(C₆F₅)₃ at the terminal carbon atom of the butadiene ligand to yield the dipolar substituted π-allyl-type betaine complex (lig)Ni[η ³-C₃H₄-CH₂B(C₆ F₅)₃] (Z-6a). At 90 °C the kinetically formed product equilibrated with its E-6a isomer. Similarly, 4a adds the boron Lewis acid (pyrrolyl)B(C₆F₅)₂ to yield the corresponding neutral dipolar π-allyl betaine complex Z-7a, that slowly equilibrated with E-7a over several hours at ambient temperature. Protonation of the butadiene ligand of complex 4a was achieved by treatment with the neutral Br?nsted acid (2H-pyrrol) B(C₆F₅)₃ to yield the [(lig)Ni (η³-crotyl)⁺][(pyrrolyl)B(C₆ F₅)₃^-] salt 9a (Z-/E-9a ratio=90:10 upon preparation). At 298 K this salt rearranged to a 5:95 mixture of Z-9a/E-9a with a Gibbs activation energy of Δ G ^? (298 K)=22.3±0.2 kcal mol^-1. Complex 4a added [Ph₃C⁺] to the butadiene ligand to yield the salt [(lig)Ni(η³-C₃H₄-CH₂ CPh₃)⁺][B(C₆F₅)₄ ^-] (Z-12a), that proved isomerically stable under the applied reaction conditions. Similar reactions were carried out starting from the acenaphthylene 1,2-dione derived chelate bis(imine)Ni(butadiene) complex 4b. The systems 6, 7, 9 and 12 were found to be active ethene polymerization catalysts in the presence of Al(i-Bu)₃.

Full text of DOI:10.1016/S0022-328X(03)00699-5

Journal of Organometallic Chemistry 683 (2003) 249Á260
/
www.elsevier.com/locate/jorganchem
Preparation of chelate bis(imine)nickel allyl systems by reaction of
their corresponding butadiene complexes with electrophiles
Joachim W. Strauch, Gerald Kehr, Gerhard Erker *
Organisch-Chemisches Institut der Universitat Munster, Corrensstrasse 40, D-48149 Munster, Germany
¨ ¨ ¨
Received 18 July 2003
Abstract
The chelate 1,2-bis(imine)nickel(butadiene) complex 4a (chelate ligand derived from condensation of biacetyl with 2,6-
diisopropylaniline) adds the strong Lewis acid B(C6F5)3 at the terminal carbon atom of the butadiene ligand to yield the dipolar
substituted p-allyl-type betaine complex (lig)Ni[h3-C3H4-CH2B(C6F5)3] (Z-6a). At 90 8C the kinetically formed product equilibrated
with its E-6a isomer. Similarly, 4a adds the boron Lewis acid (pyrrolyl)B(C6F5)2 to yield the corresponding neutral dipolar p-allyl
betaine complex Z-7a, that slowly equilibrated with E-7a over several hours at ambient temperature. Protonation of the butadiene
ligand of complex 4a was achieved by treatment with the neutral Brønsted acid (2H-pyrrol)B(C6F5)3 to yield the [(lig)Ni(h3-
crotyl)ꢀ][(pyrrolyl)B(C6F5)3ꢁ] salt 9a (Z-/E-9a ratioꢂ
Z-9a/E-9a with a Gibbs activation energy of DG% (298 K)ꢂ
/
90:10 upon preparation). At 298 K this salt rearranged to a 5:95 mixture of
22.39
0.2 kcal molꢁ1. Complex 4a added [Ph3Cꢀ] to the butadiene
/
/
ligand to yield the salt [(lig)Ni(h3-C3H4-CH2CPh3)ꢀ][B(C6F5)4ꢁ] (Z-12a), that proved isomerically stable under the applied reaction
conditions. Similar reactions were carried out starting from the acenaphthylene 1,2-dione derived chelate bis(imine)Ni(butadiene)
complex 4b. The systems 6, 7, 9 and 12 were found to be active ethene polymerization catalysts in the presence of Al(i-Bu)3.
# 2003 Published by Elsevier B.V.
Keywords: (Butadiene)nickel complexes; Boron Lewis acids; Metal boron betaines; (p-Allyl)nickel complexes; Ethene polymerization.
1. Introduction
formation of a substituted h3-allyl moiety. The resulting
complexes show a variety of features of typical (al-
lyl)metal cation systems, only that the dipolar complexes
2 are overall neutral, because they have their counter
anion covalently attached to the allyl ligand framework
(see Scheme 1) [6,7].
(Allyl)nickel complexes have played an important role
in the development of homogeneous catalysis using
structurally well defined mono-nuclear transition metal
complexes [1]. Most noteworthy in the early work is the
chemistry of the neutral (allyl)Ni systems, which is of
great importance, e.g. in the cyclooligomerization and
cooligomerization of butadiene [2]. Chelate Schiff-base
nickel cation complexes and related systems have been
of interest in polymerization catalysis [3]. We had
recently shown that strongly electrophilic neutral bor-
anes, such as B(C6F5)3 [4], can add to the butadiene
ligands of a variety of metal complexes, especially of the
early transition metals [5]. The borane addition occurs
at a terminal CH2 group of the butadiene ligand with
In the case of the nickel systems, the addition of, e.g.
B(C6F5)3 to neutral LnNi(butadiene) complexes of Ni(0)
would then yield dipolar LnNi[C4H6ÁB(C6F5)3] type
/
complexes, featuring a local (allyl)Ni(II) type subgroup
inside an overall neutral ‘betaine’ complex. We have
prepared a few examples of such systems [8], that may
chemically be placed at an intermediate position be-
tween the classical neutral (allyl)Ni complexes and the
charged [(allyl)Niꢀ] cations, by the addition of strongly
electrophilic boranes to (butadiene)nickel complexes,
and we have compared some of the chemical features
of such dipolar systems with closely related (allyl)nickel
cations that were made by Hꢀ or carbenium ion
* Corresponding author. Fax: ꢀ49-251-8336-503.
E-mail address: erker@uni-muenster.de (G. Erker).
/
0022-328X/03/$ - see front matter # 2003 Published by Elsevier B.V.
doi:10.1016/S0022-328X(03)00699-5

250
J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á260
/
100.7 (C3), and a broad C4 resonance at d 26 (see Table
1
1). The H-NMR spectrum of the C3H4-CH2[B] section
of Z-6a shows a six hydrogen pattern of signals that is
typical for the presence of a Z-substituted h3-allyl
moiety [14]. It features the 1-Hsyn and 1-Hanti signals
at d 2.48 and d 2.57, respectively. Their mutual coupling
(2J) is so small that it was not resolved in this case. The
2-H (d 4.88) shows a small cis-coupling constant with 1-
Scheme 1.
addition to the same (butadiene)nickel complex precur-
sors.
Hsyn [3J(2-H,1-Hsyn)ꢂ
/
7.2 Hz] and a large trans-cou-
14.3 Hz].
pling constant with 1-Hanti [3J(2-H,1-Hanti)ꢂ
/
3
2. Results and discussion
Most significantly, the J(2-H,3-H) coupling constant
was found at 7.2 Hz, i.e. in the typical cis-range, which
indicates the presence of the Z-6a isomer in solution
under the applied conditions. The adjacent 4-H/H?
resonances occur at d 2.00/1.03.
As the starting materials for our study we have
employed the chelate bis(imine)nickel complex systems
derived from 3a and 3b. The chelate ligands were
synthesized by treatment of the corresponding 1,2-
diketones with two molar equivalents of 2,6-diisopro-
pylphenylamine under acidic conditions. Subsequent
treatment with (dme)NiBr2 gave the bis(imine)NiBr2
complexes (3a, 3b) that had previously been used
The attachment of the unsymmetrically substituted p-
allyl moiety at the nickel center makes complex Z-6a
chiral and the two halves of the substituted bis(imine)
ligand have become different. Consequently, a pair of
core methyl NMR resonances are observed (1H: d 1.16/
1.15, 13C: 19.5/18.4) and we have monitored a total of
four isopropyl CH resonances (13C: d 30.6, 29.5, 29.1,
28.6) and eight isopropyl CH3 signals (for details see
Section 3) (Scheme 3).
extensively in homogeneous ZieglerÁNatta catalysis
/
[9,10]. The corresponding chelate bis(imine)Ni(buta-
diene) complexes (4a, 4b) had been described by tom
Dieck et al. [11]. They were prepared according to the
literature procedure described by treatment of the
Complex Z-6a rearranges at elevated temperature.
During a period of 1 h at 90 8C (in toluene-d8) it is
equilibrated with its isomer E-6a. After 1 h a ca. 1:1
mixture of the two isomers was present in solution.
From the mixture the typical NMR signals of the E-6a
complexes 3 with the ‘butadieneÁ
/
magnesium’ reagent
[12,13] (Scheme 2).
We then treated complex 4a with B(C6F5)3 (5a). One
molar equivalent of the strong boron Lewis acid was
rapidly added to give the product Z-6a, that was
isolated in ca. 80% yield. We had characterized complex
Z-6a by X-ray diffraction [8]. The X-ray crystal
structure analysis had shown that the borane addition
1
isomer were obtained. The H-NMR spectrum features
allyl resonances at d 2.05, 1.39 (1-Hsyn, 1-Hanti), d 4.71
3
(2-H), and d 4.00 (3-H) with coupling constants J(2-
H,1-Hsyn)ꢂ
/
7.2 Hz, 3J(2-H,1-Hanti)ꢂ
/
13.8 Hz, and
3J(2-H,3-H)ꢂ
/13.8 Hz. The latter clearly characterizes
had taken place at the terminal ꢀ
/
CH2 group of the
conjugated diene ligand. The NMR analysis of Z-6a
showed the analogous structure to be present in solu-
tion. The C4H6-[B] ligand features four characteristical
13C-NMR resonances at d 54.3 (C1), d 110.9 (C2), d
that the isomer E-6a had been formed subsequently
upon thermolysis of Z-6a, which was formed under
kinetic control. The acenaphthen-derived butadiene
nickel complex 4b was similarly converted to Z-6b (ca.
90% isolated, for details see Section 3).
We had recently described a heterocyclic variant of
tris(pentafluorophenyl)borane (5a), namely N-pyrrolyl-
bis(pentafluorophenyl)borane (5b) [15]. It is slightly less
strongly electrophilic than the commonly used 5a, but
was shown to exhibit similar features as an activator
component in homogeneous ZieglerÁNatta catalysis [15]
/
The Lewis acid 5b adds cleanly to the butadiene ligands
of either of the nickel complexes 4a and 4b to yield the
dipolar
‘betaine’ complexes 7a and 7b. These complexes were
isolated in ꢀ70% yield in each case.
(p-allyl)Ni[p-C3H4Á
/
CH2Á/B(C6F5)2(NC4H4)]
/
When the components 4a and 5b were mixed at
ꢁ
/
78 8C in toluene-d8 and the solution was allowed to
warm to room temperature a 90:10 mixture of the
isomers Z-7a and E-7a was obtained. Again the Z-
isomer proved to be the kinetically formed product. In
Scheme 2.
the case of the 5b addition product, the Z-7a=
/E-7a

J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á
/260
251
Table 1
Selected 1H- and 13C-NMR chemical shifts of the Z- and E-allyl nickel products obtained from the addition of electrophiles to 4a and 4b a
Complex
1Hsyn
1Hanti
2-H
3-H
4-H
4-H?
C1
C2
C3
C4
d
Z-6a
E-6a c
Z-6b
Z-7a b
E-7a b
Z-9a
2.48
2.05
2.87
2.52
2.24
2.86
2.60
2.92
2.40
2.73
2.57
1.39
2.99
2.08
1.73
2.53
2.34
2.55
1.96
2.33
4.88
4.71
5.10
5.00
4.57
5.56
5.31
5.53
5.18
5.42
4.08
4.00
4.64
4.12
3.68
3.62
3.23
3.51
3.61
3.82
2.00
1.03
0.37
1.45
1.15
0.10
54.3
E
110.9
e
100.7
e
26
e
1.20
2.32
1.36
0.87
0.60
54.6
53.8
e
110.7
110.8
114.4
115.5
119.4
118.7
116.1
115.6
100.8
97.5
99.0
79.2
80.1
78.7
76.9
75.5
27 d
25 d
e
f
Á/
Á/
Á/
1.64
1.84
58.3
59.7
59.0
60.4
60.3
14.9
15.0
15.4
39.1
39.2
E-9a
E-9b
ꢁ
/
0.03 f
0.17 f
2.60
Z-12a
Z-12b
2.76
a
In CD2Cl2 except 6a and 6b (toluene-d8), 600 MHz (1H), 150.8 MHz (13C) at 298 K.
At 268 K.
At 358 K.
b
c
d
e
f
Broad signal.
Not determined.
CH3 group.
interconversion was, however, much faster then the Z-
6a=E-6a conversion described above. In the case of the
7a isomers it was sufficient to leave the system at room
/
temperature for 6 h to achieve a 50% conversion to E-
1
7a. Fig. 1 shows the TOCSY H-NMR spectrum of the
ca. 1:1 Z-/E-7a mixture featuring the well separated
system of the six coupled proton resonances of the h3-
C3H4-CH2-[B] subunit of the E-7a isomer (top) distin-
guished from the corresponding set of signals originat-
ing from the Z-7a isomer. A detailed analysis of the
3
spectra showed again the typical small J(2-H,3-H)ꢂ
/
8.0 Hz of Z-7a, whereas E-7a features a much larger
3
value of J(2-H,3-H)ꢂ13.4 Hz (see also Table 1).
/
Complex Z-7a again features four diastereotopic
isopropyl groups (1H-NMR: d 3.79, 3.15, 2.82, 2.56,
each sept. 1 H, CHMe2). Due to the chirality of the
system, the methyl groups of each separate isopropyl
group are diastereotopic, which gives rise to a set of each
Fig. 1. TOCSY 1H-NMR spectra of the (h3-C3H4-CH2-[B] subunit of
E-7a (top) and Z-7a (bottom) (CD2Cl2, 600 MHz, 268 K).
(pyrrolyl[B] 13C). The 11B-NMR resonance of Z-7a is
1
eight observed H- and 13C-NMR isopropyl-CH3 reso-
found at d ꢁ6.9 (Scheme 4).
/
nances. The pyrrolyl 13C-NMR resonances of Z-7a
occur at d 122.7 and d 106.3. The corresponding signals
of the isomer E-7a were observed at d 123.0 and d 106.0
Protonation of the butadiene ligand in 4a or 4b should
give rise to the formation of a cationic chelate
[bis(imine)Ni(crotyl)ꢀ] cation complex. As a suitable
Scheme 3.

252
J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á
/260
Scheme 4.
Brønsted acid we have used the neutral 2H-pyrrol/
B(C6F5)3 adduct 8. The reagent 8 is readily prepared
by the addition of N-pyrrolyl lithium to B(C6F5)3
followed by the reaction with hydrogen chloride in ether
[16,17]. Compound 8 had successfully been applied
previously as a suitable Hꢀ source for the protonolysis
of sensitive early metal cation systems. The resulting
[(pyrrolyl)B(C6F5)3ꢁ] anion shows a sufficiently low
nucleophilicity [18] for the generation of such systems.
Proton transfer from 8 to 4a took place readily. At
low temperature, the Z-crotyl nickel cation complex Z-
It is remarkable how different the rates of Z- to E-h3-
allyl isomerizations (qualitatively) are in the series of the
complexes 6, 7 and 9. One obvious structural difference
between these compounds lies in the steric bulk of the
Á
CH2X group that is attached at the essential allyl sp2
/
carbon atom C3, that needs to undergo an inplane
inversion during the isomerization process. This is likely
to occur through the corresponding s-allyl intermediate
(10) [19]. In 10 the nickel center together with its very
bulky 2,6-diisopropylphenyl substituted chelate bis
(imine) ligand will probably get closer to the allyl bound
ÁCH2X substituent. Thus, the isomerization rate is
/
9a was rather selectively formed (Z-/E-9aꢂ90:10).
/
likely to respond to the sterical features of the X-group
that has become connected to the former butadiene C4
carbon center (see Scheme 6).
During ca. 4 h at 298 K it rearranged to a 5:95 mixture
of Z-9a and E-9a. The Gibbs activation energy of the
thermally induced Z-9a to E-9a rearrangement was
From this interpretation it is expected that the
initially formed Z-isomer is ever more effectively
protected from undergoing a subsequent thermally
induced isomerization to the thermodynamically favored
respective E-isomer if the substituent at C4 is increased
in size. As an experimentally feasible extreme case we
have, therefore, treated both the complexes 4a and 4b
with trityl perfluorotetraphenylborate (11) [20]. In both
cases the very bulky trityl cation electrophile added
cleanly to the butadiene ligand to form the respective
substituted chelate bis(imine) p-allyl nickel cation salts.
In both cases only the Z-configurated products (Z-12a,
Z-12b, see Scheme 7) were obtained. They were isolated
in 76 and 89% yield, respectively. Both did not isomerize
to their respective E-isomers. They proved to be stable
with regard to isomerization under the applied condi-
tions.
determined at DG% (298 K)ꢂ
/
22.29 .
0.2 kcal molꢁ1
Again, the kinetically predominantly formed complex
/
3
Z-9a is characterized by a coupling constant of J(2-
H,3-H)ꢂ
/
7.8 Hz, whereas the E-9a isomers features a
much larger value of 3J(2-H,3-H)ꢂ
details see Table 1 and Section 3) (Scheme 5).
/13.4 Hz (for further
The protonation of the acenaphthylene-derived
Ni(butadiene) complex 4b with 8 also proceeds cleanly.
In this case only traces of the Z-9b isomer could be
found. After work-up almost pure E-9b (3J(2-H,3-H)ꢂ
/
13.3 Hz) was found (81% isolated).
Both the betaine systems (6,7) and the substituted p-
allyl nickel cation complexes (9) were low activity
catalysts for ethene polymerization [10] in the presence
of a ca. 50-fold excess of tri-isobutyl aluminum. It was
checked in a NMR study, that the Z-6a system did not
react itself even at 85 8C with a ca. twofold excess of
Al(i-Bu)3. So it remains to be resolved whether the
added aluminum compound is actively involved in the
polymerization process or if it merely acts as a moisture
scavenger. In the latter case the systems 6 and 7 would
serve as model catalyst systems for explaining possible
olefin activation pathways at an increasingly observed
homogeneous catalyst type that is derived from im-
Scheme 5.

J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á
/260
253
Scheme 6.
by 13C-NMR spectroscopy [3b,25]. It was very similar
for the samples listed in Table 2 which typically
exhibited around 100 methyl branches per 1000 chain
carbon atoms, half of which were randomly distributed
and the remaining ones were 1,4-positioned to other
CH3 groups along the chain. In addition, the signals of
very small amounts of longer branches (ethylꢀ
/
propylꢀ
/
butyl) could just be identified in the 13C-
NMR spectra of the polymer samples.
3. Experimental
Scheme 7.
General information: reactions with organometallic
reagents were carried out under argon in Schlenk-type
glassware or in a glove-box. Solvents were dried and
distilled under argon prior to use. For additional general
information, including a list of spectrometers and
equipment used for physical characterization see Ref.
[26]. NMR assignments were in most cases derived from
a series of 2D-NMR experiments [27]. The boron
reagents 5a [4], 5b [15] and 8 [16] were prepared as
described in the literature. The (butadiene)nickel com-
plexes 4a and 4b were synthesized according to literature
procedures [11].
Table 2
Ethene polymerization with the allyl nickel-type complexes a
b
b
Complex
mmol cat.
Mn (ꢃ
/
103)
D
g PE c
Act d
6a
6b
39
33
39
33
39
33
39
33
700
130
400
140
600
220
1.70 12.2
1.98 15.3
159
231
81
7a
7b
1.78
1.94
1.73
1.82
6.3
5.0
4.4
4.5
4.9
5.5
76
57
9a
9b
68
63
12a
12b
73
e
1.93
e
78
a
In 200 ml toluene at 25 8C, with 0.5 ml Al(i-Bu)3 added, 2 bar
ethene.
b
3.1. Reaction of tris(pentafluorophenyl)borane (5a) with
[biacetylbis(2,6-diisopropylphenylimin)](1,3-
butadiene)nickel (4a), preparation of 6a
Mn and polydispersity determined by GPC vs. polystyrene
standard in THF at 35 8C.
g Polyethylene obtained after 1 h reaction time.
c
d
Catalyst activity in kg PE/mol catꢃ
Insoluble polymer, M not determined.
/
bar(ethene)ꢃ
/h.
e
3.1.1. NMR experiments
The betaine system 6a was generated in situ by the
slow addition of a solution of the (butadiene)nickel
complex 4a (20 mg, 38.6 mmol) in 0.5 ml of toluene-d8 to
a solution of 19.8 mg (39.6 mmol) of B(C6F5)3 (5a) in 0.5
ml toluene-d8 at ambient temperature. Initially, only the
formation of Z-6a was observed. Warming to 90 8C
resulted in the rearrangement to E-6a. After 1 h at 90 8C
the NMR signals of a 1:1 mixture of Z-6a and E-6a
were monitored. From the dark-purple colored solution
the betaine precipitated as a dark colored solid during
several days at room temperature (r.t.).
mediate catalyst precursors that are lacking a necessary
metal to carbon s-bond [21Á23]. The polyethylenes
obtained at the 6,7,9/Al(i-Bu)3 catalyst (see Table 2)
have a branched structure, as it is commonly observed at
chelate bis(imine)Ni-derived catalyst systems [9,24]. The
branching of the obtained polyethylenes was analyzed
/

254
J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á260
/
3.1.2. Preparation of 6a
2.29 (each sept, each 1H, 3JHH
(d, 1H, 3JHH 14.3 Hz, 1anti-H), 2.48 (d, 1H, 3JHH
Hz, 1syn-H), 2.00 (br, 1H, 4?-H), 1.57, 1.49, 1.12, 1.01,
0.98, 0.97, 0.92, 0.77 (each d, each 3H, 3JHH
7.2 Hz, i-
PrÁCH3), 1.16, 1.15 (each s, each 3H, NCÁCH3), 1.03
(br, 1H, 4-H). 13C{1H}-NMR (150.8 MHz, benzene-d6,
298 K): dꢂ173.1, 172.5 (each Cꢀ
N), 148.1 (dm, 1JCF
240 Hz, o-B(C6F5)3), 143.1, 141.1 (ipso-Ph), 138.4 (dm,
1JCF
250 Hz, p-B(C6F5)3), 138.2, 137.6, 137.5, 136.0
(each quart. C-CH(CH3)2), 136.7 (dm, JCF
ꢂ
/
7.2 Hz, i-PrÁ
/
CH), 2.57
At ꢁ
/
78 8C a precooled solution of B(C6F5)3 (5a) (198
ꢂ
/
ꢂ/7.2
mg, 387 mmol) in 20 ml of toluene was added dropwise
with stirring to a solution of 200 mg (387 mmol) of 4a in
20 ml of toluene. The mixture was stirred for 30 min and
then warmed to room temperature during 2 h. The dark-
purple solution was stirred for 4 h at ambient tempera-
ture and then the solvent was removed in vacuo. The
residue was suspended in pentane (30 ml). The resulting
ꢂ
/
/
/
/
/
ꢂ
/
ꢂ
/
1
ꢂ250 Hz,
/
brown precipitate was washed with pentane (3ꢃ10 ml)
/
m-B(C6F5)3), 128.0, 127.8, 124.2, 124.1, 123.8, 123.5
(each Ph), 110.9 (C2), 100.7 (C3), 54.3 (C1), 30.6, 29.5,
and dried in vacuo to yield 321 mg (81%) of 6a, m.p.
212 8C dec. Anal. Calc. for C50H46BF15N2Ni (M
1029.4): C, 58.34; H, 4.50; N, 2.72. Found: C, 58.64;
H, 4.81; N, 2.76%.
29.1, 28.6 (each i-PrÁ
23.9, 23.3, 22.7, 22.2, 22.1 (each i-PrÁ
(each NC-CH3). ipso-C of C6F5 not detected. 19F-NMR
/CH), 26 (br, C4), 24.4, 24.2, 24.0,
/
CH3), 19.5, 18.4
(599.9 MHz, benzene-d6, 298 K): dꢂ
/
-166.5 (m, 6F, m-
19 Hz, 3F, p-B(C6F5)3),
3
B(C6F5)3), -163.0 (t, JFF
ꢂ
/
ꢁ
130.5 (m, 6F, o-B(C6F5)3). 11B{1H}-NMR (64.2
/
MHz, benzene-d6, 298 K): dꢂ
2971, 2932, 2874, 1643, 1517, 1459, 1388, 1283, 1223,
1085, 991, 898 cmꢁ1
/
ꢁ
/
14.0. IR (KBr): n˜
/
ꢂ
/
.
3.2. Reaction of the (butadiene)Ni complex 4b with
B(C6F5)3, formation of 6b
3.2.1. NMR experiment
1H-NMR (599.9 MHz, toluene-d8, 358 K): dꢂ
/
7.03 (t,
7.7 Hz,
Complex 6b was generated in situ by treatment of 30.0
mg (48.9 mmol) of 4b in 0.5 ml toluene-d8 with
25.0 mg (48.9 mmol) of B(C6F5)3 (5a) in 0.5 ml of
toluene-d8 at ambient temperature. The NMR spectra of
the product (see below) were obtained from this experi-
ment.
3
1H, JHH
3
7.7 Hz, p-Ph), 6.95 (d, 2H, JHH
ꢂ
/
ꢂ
/
3
m-Ph), 6.89 (t, 1H, JHH
ꢂ7.7 Hz, p-Ph), 6.86 (d, 2H,
/
3
7.7 Hz, m-Ph), 4.71 (d t, 1H, JHH
3JHH
3JHH
3JHH
ꢂ
/
ꢂ/13.8 Hz,
3
7.2 Hz, 2-H), 4.00 (ddd, 1H, JHH
ꢂ
/
ꢂ/13.8 Hz,
3
ꢂ
/
13.2 Hz, JHH
ꢂ
/
7.8 Hz, 3-H), 2.95, 2.91, 2.62,
6.8 Hz, i-PrÁCH), 2.05
7.2 Hz, 1syn-H), 1.39 (d, 1H, 3JHH
13.8
Hz, 1anti-H), 1.27, 1.20 (each s, each 3H, NCÁCH3), 1.20
(br, 1H, 4?-H), 1.36, 1.31, 1.03, 0.99, 0.89, 0.87, 0.80,
2.59 (each sept, each 1H, 3JHH
(d, 1H, 3JHH
ꢂ
/
/
ꢂ
/
ꢂ
/
3.2.2. Preparation of Z-6b
/
The betaine 7 was prepared by treatment of B(C6F5)3
(5a, 167 mg, 326 mmol) with 4b (200 mg, 326 mmol)
in a total volume of 40 ml of toluene analogously as
described above to yield 334 mg (91%) of
the dark violet product Z-6b, m.p. 182 8C (dec.). Anal.
Calc. for C58H46BF15N2Ni (M 1125.5): C, 61.90; H,
4.12; N, 2.49. Found: C, 62.09; H, 4.57; N, 2.40%.
3
0.72 (each d, each 3H, JHH
(br, 1H, 4-H).
ꢂ
/
6.8 Hz, i-PrÁCH3), 0.37
/
1H-NMR (599.9 MHz, toluene-d8, 298 K): dꢂ
/
7.26 (t,
7.7 Hz,
3
1H, JHH
3
7.7 Hz, p-Ph), 7.09 (d, 2H, JHH
ꢂ
/
ꢂ
/
3
m-Ph), 7.05 (t, 1H, JHH
ꢂ7.7 Hz, p-Ph), 6.96 (d, 2H,
/
3
7.7 Hz, m-Ph), 4.88 (dt, 1H, JHH
7.2 Hz, 2-H), 4.08 (br, 1H, 3-H), 3.73, 2.98, 2.64,
3JHH
3JHH
ꢂ
/
ꢂ14.3 Hz,
/
ꢂ
/
1H-NMR (599.9 MHz, toluene-d8, 298 K): dꢂ
7.40 (t,
/

J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á
/260
255
3
1H, JHH
3
8.4 Hz, p-Ph), 7.20 (d, 1H, JHH
ꢂ
/
ꢂ
/
8.4 Hz,
temperature. Some NMR signals of the E-isomer
were broad under the conditions of the NMR measure-
ments.
m-Ph), 7.19-7.13 (m, 4H, p-, m-Ph), 7.13 (d, 1H, 3JHH
ꢂ
/
3
7.8 Hz, napht.), 7.08 (d, 1H, JHH
ꢂ7.8 Hz, napht.),
/
6.62 (t, 1H, 3JHH
ꢂ
/
7.8 Hz, napht.), 6.59 (d, 1H, 3JHH
7.8 Hz, napht.), 6.47
7.8 Hz, napht.), 5.10 (dt, 1H, 3JHH
13.8
7.4 Hz, 2-H), 4.64 (br, 1H, 3-H), 4.04, 3.41,
ꢂ
/
7.8 Hz, napht.), 6.54 (t, 1H, 3JHH
ꢂ
/
(d, 1H, 3JHH
ꢂ
/
ꢂ
/
3
Hz, JHH
ꢂ
/
3
3.17, 2.84 (each sept, each 1H, JHH
ꢂ
/
7.2 Hz, i-PrÁ
13.8 Hz, 1anti-H), 2.87 (d,
7.4 Hz, 1syn-H), 2.32 (br, 1H, 4?-H), 1.57,
1.53, 1.20, 1.03, 0.96, 0.77, 0.74, 0.63 (each d, each 3H,
3JHH CH3), 1.45 (br, 1H, 4-H). 13C{1H}-
7.2 Hz, i-PrÁ
NMR (150.8 MHz, benzene-d6, 298 K): dꢂ
/
3
CH), 2.99 (d, 1H, JHH
ꢂ
/
3
1H, JHH
ꢂ
/
ꢂ
/
/
/170.4, 170.2
1
(each C ꢀ
/
N), 148.6 (dm, JCF
ꢂ/240 Hz, o-B(C6F5)3),
145.3, 131.6, 131.3, 125.3 (each quart. napht.), 143.4,
1
141.9 (ipso-Ph), 137.2 (dm, JCF
137.1, 139.3, 138.6 (each quart. C-CH(CH3)2), 138.4
ꢂ250 Hz, p-B(C6F5)3),
/
1
(dm, JCF
1H-NMR (599.9 MHz, CD2Cl2, 268 K): dꢂ
7.26 (m, 6H, Ph), 6.39 (s, 2H, pyrrol), 5.85 (pt, 2H,
pyrrol), 4.57 (d t, 1H, 3JHH 13.4 Hz, 3JHH
8.0 Hz, 2-
H), 3.69 (br m, 1H, 3-H), 3.13, 3.05, 2.82, 2.71 (each
/
7.45Á
/
ꢂ250 Hz, m-B(C6F5)3), 128.7, 128.6, 125.6,
/
125.1, 125.0, 124.8 (napht.), 128.0, 127.8, 124.2, 124.1,
123.8, 123.5 (Ph), 110.7 (C2), 100.8 (C3), 54.6 (C1), 30.8,
ꢂ
/
ꢂ
/
29.9, 29.5, 29.0 (each i-PrÁ
24.1, 24.0, 23.4, 23.0, 22.4, 22.1 (each i-PrÁ
NMR (599.9 MHz, benzene-d6, 298 K): dꢂ
/
CH), 27 (br, C4), 25.2, 24.5,
CH3). 19F-
166.2 (m,
17 Hz, 3F, p-
130.6 (m, 6F, o-B(C6F5)3). 11B{1H}-
NMR (64.2 MHz, benzene-d6, 298 K): dꢂ 14.0. IR
(KBr): n˜ 2967, 2932, 2874, 1644, 1516, 1458, 1389,
1276, 1084, 972, 799 cmꢁ1
3
/
sept, each 1H, JHH
3JHH
8.0 Hz, 1syn-H), 2.10-1.95 (br, 6H, NC-CH3),
1.73 (m, 1H, 1anti-H), 1.43, 1.32, 1.29, 1.28, 1.25, 1.22,
ꢂ
/
6.8 Hz, i-PrÁ
/
CH), 2.24 (d, 1H,
/
ꢁ
/
ꢂ
/
3
6F, m-B(C6F5)3), ꢁ
/
162.8 (t, JFF
ꢂ
/
3
B(C6F5)3), ꢁ
/
1.15, 1.08 (each d, each 3H, JHH
0.87 (m, 1H, 4?-H), 0.10 (br, 1H, 4-H). 13C{1H}-NMR
ꢂ
/
6.8 Hz, i-PrÁCH3),
/
/
ꢁ
/
(150.8 MHz, CD2Cl2, 268 K): dꢂ
/
147.5 (dm, 1JCF
ꢂ230
/
/
ꢂ
/
1
Hz, o-B(C6F5)3), 138.1 (dm, JCF
.
ꢂ235 Hz, p-
/
1
B(C6F5)3), 136.6 (d, JCF
ꢂ240 Hz, m-B(C6F5)3),
/
3.3. Addition of (N-pyrrolyl)B(C6F5)2 (5b) to the
(butadiene)nickel complex 4a, formation of 7a
128.4, 128.2, 124.8 (br), 124.6 (br), 124.3 (br), 124.0
(each Ph), 123.0, 106.0 (pyrrol-CH), 114.4 (C2), 99.0
(C3), 29.6 (br), 29.5 (br), 29.1, 28.6 (each i-PrÁ
24.1, 23.6, 23.5, 23.3, 23.2, 23.1, 22.7, 22.6 (each i-PrÁ
CH3).
/
CH),
3.3.1. NMR experiments
/
For the in situ generation of 7a two separate solutions
were prepared by dissolving 4a (30.0 mg, 58.0 mmol) in
0.5 ml CD2Cl2 by 5b (23.8 mg, 58.0 mmol) in 0.5 ml
CD2Cl2. Then the borane solution was slowly added to
the (butadiene)Ni solution by pipette. The resulting
product solution was used to monitor the NMR spectra
of 7a.
3.3.2. Preparation of 7a
At ꢁ78 8C a solution of 159 mg (386 mmol) of the
/
boron reagent 5b in 20 ml CH2Cl2 was added to a
solution of 4a (200 mg, 386 mmol) in 20 ml of
dichloromethane. After 30 min the mixture was allowed
to warm to r.t. and then stirred for 2 h. Solvent was
removed in vacuo, the residue suspended in 50 ml of
pentane and the solid collected by filtration. The
product was washed with pentane (3ꢃ10 ml) and dried
/
1H-NMR (599.9 MHz, CD2Cl2, 268 K): dꢂ
7.26 (m, 6H, Ph), 6.20 (s, 2H, pyrrol), 5.80 (pt, 2H,
/
7.45Á
/
in vacuo to yield 292 mg (79%) of 7a, m.p. 195 8C (dec.).
Anal Calc. for C48H50BF10N3Ni (M 928.4): C, 62.10; H,
5.43; N, 4.53. Found: C, 62.40; H, 5.86; N, 4.19%. A
90:10 mixture of Z-7a and E-7a was isolated. In
solution a rearrangement was observed to yield a ca.
50:50 mixture of the isomers after 6 h at ambient
3
pyrrol), 5.00 (dt, 1H, JHH
ꢂ
/
15.0 Hz, 3JHH
H), 4.12 (br m, 1H, 3-H), 3.79, 3.15, 2.82, 2.56 (each
ꢂ8.0 Hz, 2-
/
3
sept, each 1H, JHH
ꢂ
ꢂ
/
6.8 Hz, i-PrÁ
/
CH), 2.52 (dd, 1H,
1.95 (br,
2
8.0 Hz, JHH
3JHH
ꢂ
/
/
1.8 Hz, 1syn-H), 2.10Á
/

256
J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á260
/
6H, NC-CH3), 2.08 (m, 1H, 1anti-H), 1.51, 1.47 (each d,
each 3H, 3JHH
6.8 Hz, i-PrÁCH3), 1.36 (br, 1H, 4?-H),
1.24-1.20 (m, 15H, i-PrÁCH3), 1.15 (m, 1H, 4-H), 1.05
6.8 Hz, i-PrÁ
CH3). 13C{1H}-NMR
(150.8 MHz, CD2Cl2, 268 K): d ꢂ174.1 (br, C ꢀN),
230 Hz, o-B(C6F5)3),
5.09; N, 3.39%. Initially a 90:10 ratio of Z-9a and E-9a
was found that changed during 10 h at ambient
ꢂ
/
/
/
temperature in solution to Z-9a:E-9aꢂ5:95.
/
3
(d, 3H, JHH
ꢂ
/
/
/
/
1
173.8 (C ꢀ
143.8, 142.4 (ipso-Ph), 138.1 (dm, JCF
B(C6F5)3), 138.8, 138.4, 138.3, 138.0 (each quart. C-
/
N), 147.5 (dm, JCF
ꢂ
/
1
ꢂ235 Hz, p-
/
1
CH(CH3)2), 136.6 (dm, JCF
ꢂ240 Hz, m-B(C6F5)3),
/
128.5, 128.4, 125.0, 124.5, 124.4, 124.3 (each Ph), 122.7,
106.3 (pyrrol), 110.8 (C2), 97.5 (C3), 53.8 (C1), 30.4 (br),
29.6 (br), 29.0, 28.6 (each i-PrÁ
24.0, 23.7, 23.2, 22.4, 22.2 (each i-PrÁ
br, NC-CH3), 25 (br, C4). 19F-NMR (599.9 MHz,
benzene-d6, 298 K): dꢂ 131.2 (m, 6F, o-B(C6F5)3),
158.4 (t, 3F, p-B(C6F5)3), ꢁ162.6 (m, 6F, m-
B(C6F5)3). 11B{1H}-NMR (64.2 MHz, benzene-d6, 298
K): dꢂ 6.9. IR (KBr): n˜ 2967 (s), 2932 (w), 2731 (w),
1644 (m), 1458 (vs), 1385 (m), 1273 (w), 1215 (w), 1088
(s), 977 (s), 795 (m), 734 (m) cmꢁ1
/
CH), 25.0, 24.2, 24.1,
/
CH3), 27, 20 (each
/
ꢁ
/
ꢁ
/
/
/
ꢁ
/
/
ꢂ
/
1H-NMR (599.9 MHz, CD2Cl2, 298 K): dꢂ
7.42-7.33
/
.
(m, 6H, Ph), 6.56 (s, 2H, pyrrol), 5.84 (s, 2H, pyrrol),
5.31 (ddd, 1H, 3JHH
7.2 Hz, 2-H), 3.30 (sept, 1H, JHH
ꢂ
/
13.4 Hz, 3JHH
ꢂ
/
13.2 Hz, 3JHH
6.8 Hz, i-PrÁCH),
6.3 Hz, 3-H), 3.10,
6.8 Hz, i-PrÁ
ꢂ
/
3.4. Reaction of (N-pyrrolyl)B(C6F5)2 (5b) with 4b,
formation of 7b
3
ꢂ
ꢂ
/
/
3.23 (dq, 1H, 3JHH
ꢂ
/
13.4 Hz, 3JHH
/
3
A solution of 5b (134 mg, 326 mmol) in 20 ml of
2.81, 2.60 (each sept, each 1H, JHH
ꢂ
/
/
3
2
dichloromethane was added dropwise at ꢁ78 8C to a
/
CH), 2.60 (dd, 1H, JHH
ꢂ
ꢂ
/
7.2 Hz, JHH
ꢂ
ꢂ
/
2.1 Hz,
2.1 Hz,
CH3), 1.41, 1.40,
1.35, 1.34, 1.28, 1.27, 1.21, 1.19 (each d, each 3H,
3
2
solution of 4b (200 mg, 326 mmol) in 20 ml of
dichloromethane. Work-up analogously as described
above yielded 242 mg, (72%) of complex 7b, m.p.
201 8C (dec.). Anal. Calc. for C56H50BF10N3Ni (M
1024.5): C, 65.65; H, 4.92; N, 4.10. Found: C, 65.65;
1syn-H), 2.34 (dd, 1H, JHH
/
13.2 Hz, JHH
/
1anti-H), 2.16, 2.13 (each s, 3H, NCÁ
/
3JHH
ꢂ
/
ꢁ
/
6.8 Hz, i-PrÁ
/
CH3), ꢁ
/
0.03 (d, 3H, JHH
ꢂ6.3
/
3
Hz, 4-H). 13C{1H}-NMR (150.8 MHz, CD2Cl2, 298 K):
1
N), 148.4 (dm, JCF
H, 4.36; N, 3.85%. IR (KBr): n˜/
ꢂ2963 (s), 2932 (w), 2870
/
d ꢂ
/
176.8, 176.7 (each C ꢀ
/
ꢂ240
/
(w), 1644 (m), 1601 (w), 1501 (vs), 1458 (vs), 1385 (w),
1262 (m), 1088 (vs), 986 (m), 957 (s), 779 (s), 756 (m)
cmꢁ1. The NMR spectra of the product 7b were very
broad, even when generated in situ, so that a character-
ization by NMR could not be achieved.
Hz, o-B(C6F5)3), 143.9, 141.7 (ipso-Ph), 137.7 (dm,
1JCF
235 Hz, p-B(C6F5)3), 138.5, 138.0, 137.8, 137.5
(each quart. C Á
ꢂ
/
1
/
CH(CH3)2), 137.0 (dm, JCF
ꢂ240 Hz,
/
m-B(C6F5)3), 129.4, 129.3, 125.5, 125.4, 125.2, 125.1
(Ph), 125.0, 105.9 (pyrrol), 119.4 (C2), 80.1 (C3), 59.7
(C1), 30.2, 29.8, 29.7, 29.5 (each i-PrÁ
23.8, 23.6, 23.3, 23.2, 23.1, 22.9 (each i-PrÁ
20.1 (each NC-CH3), 15.0 (C4).
/
CH), 24.5, 24.2,
3.5. Reaction of 4a with the 2H-pyrrol/B(C6F5)3 adduct
8, formation of 9a
/
CH3), 20.4,
3.5.1. NMR experiments
Complex 9a was generated in situ by combining
solutions of 4a (20.0 mg, 38.7 mmol) in 0.5 ml CD2Cl2
and of 8 (22.4 mg, 38.7 mmol) in 0.5 ml of CD2Cl2. The
NMR spectroscopic characterization of the products
was carried out using the resulting product solution.
3.5.2. Preparation of 9a
A solution of 8 (168 mg, 290 mmol) in 20 ml of
dichloromethane was cooled to 0 8C. To this a solution
of 150 mg (290 mmol) of 4a in 20 ml of CH2Cl2 was
added. The mixture was stirred for 6 h and worked up
analogously as described above to yield 274 mg (86%) of
9a, m.p. 204 8C. Anal. Calc. for C54H51BF15N3Ni (M
1096.5): C, 59.15; H, 4.69; N, 3.83. Found: C, 58.90; H,

J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á
/260
257
1H-NMR (599.9 MHz, CD2Cl2, 298 K): dꢂ
(m, 6H, Ph), 6.56 (s, 2H, pyrrol), 5.84 (s, 2H, pyrrol), 5.56
(ddd, 1H, 3JHH 14.5 Hz, 3JHH 8.5 Hz, 3JHH
7.8 Hz,
7.8 Hz, 3JHH
6.3 Hz, 3-H),
6.8 Hz, i-PrÁCH), 3.09, 2.90 (each
6.8 Hz, i-PrÁCH), 2.86 (dd, 1H,
2.7 Hz, 1syn-H), 2.65 (sept, 1H,
CH), 2.53 (dd, 1H, 3JHH
14.5 Hz,
2.7 Hz, 1anti-H), 2.14, 2.12 (each s, 3H, NCÁCH3),
/7.43-7.40
ꢂ
/
ꢂ
/
ꢂ
/
2-H), 3.62 (dq, 1H, 3JHH
ꢂ
/
ꢂ
/
3.38 (sept, 1H, 3JHH
ꢂ
ꢂ
/
/
3
sept, each 1H, JHH
/
/
2
3JHH
3JHH
2JHH
ꢂ
/
8.5 Hz, JHH
ꢂ
/
ꢂ
/
6.8 Hz, i-PrÁ
/
ꢂ
/
ꢂ
/
/
1.48,1.46,1.38,1.34,1.27,1.25,1.22,1.14(eachd,each3H,
3JHH CH3), 0.60 (d, 3H, 3JHH
6.8 Hz, i-PrÁ 6.3 Hz, 4-
H). 13C{1H}-NMR (150.8 MHz, CH2Cl2, 298 K): d ꢂ
ꢂ
/
/
ꢂ
/
/
1
177.0, 176.8 (each C ꢀ
B(C6F5)3), 143.5, 142.7 (ipso-Ph), 137.7 (dm, 1JCF
Hz, p-B(C6F5)3), 138.6, 138.3, 138.0, 137.5(eachquart. C-
/
N), 148.4 (dm, JCF
ꢂ
/
240 Hz, o-
ꢂ
/
235
1
CH(CH3)2), 137.0 (dm, JCF
ꢂ240 Hz, m-B(C6F5)3),
/
129.2, 129.1, 125.3, 125.2, 125.0, 124.9 (Ph), 125.0, 105.9
(pyrrol), 115.5 (C2), 79.2 (C3), 58.3 (C1), 30.4, 30.1, 29.4
3
CH), 3.51 (dq, 1H, JHH
3
13.3 Hz, JHH
PrÁ
/
ꢂ
/
ꢂ
/
6.4 Hz,
3
3-H), 3.51, 3.14 (each sept, each 1H, JHH
ꢂ
/
6.8 Hz, i-
2.1 Hz,
CH), 2.55
2.1 Hz, 1anti-H), 1.48
), 1.43, 1.42, 1.13, 1.11, 1.01, 0.98 (each d, each 3H,
(2x)(eachi-PrÁ
23.0 (each i-PrÁ
(C4). 19F-NMR (599.9 MHz, benzene-d6, 298 K): dꢂ
130.3 (m, 6F, o-B(C6F5)3), ꢁ157.2 (t, 3F, p-B(C6F5)3),
162.6 (m, 6F, m-B(C6F5)3). 11B{1H}-NMR (64.2 MHz,
benzene-d6, 298 K): dꢂ 8.5. IR (KBr): n˜ 2971 (m),
2874 (w), 1644 (m), 1516 (s), 1462 (vs), 1385 (m), 1277 (w),
1215 (s), 1088 (s), 980 (s), 795 (w) cmꢁ1
/CH),24.6,24.5,24.3,24.1,23.5,23.4,23.2,
3
2
PrÁ
/
CH), 2.92 (dd, 1H, JHH
ꢂ
/
7.1 Hz, JHH
ꢂ
/
/
CH3), 20.9, 20.0 (each NCÁCH3), 14.9
/
3
1syn-H), 2.90 (sept, 1H, JHH
ꢂ
ꢂ
/
6.8 Hz, i-PrÁ
/
/
3
2
(dd, 1H, JHH
(2ꢃ
3JHH
4-H). 13C{1H}-NMR (150.8 MHz, CD2Cl2, 298 K): dꢂ
ꢂ
/
13.3 Hz, JHH
/
ꢁ
/
/
/
ꢁ
/
3
ꢂ
/
6.8 Hz, i-PrÁ/CH3), 0.17 (d, 3H, JHH
ꢂ6.4 Hz,
/
/
ꢁ
/
/
ꢂ
/
/
1
173.2, 173.1 (each C ꢀ
/
N), 148.4 (dm, JCF
ꢂ240 Hz, o-
/
.
B(C6F5)3), 147.8, 132.0 (napht.), 143.4, 141.3 (ipso-Ph),
1
138.8 (dm, JCF
138.5, 138.4 (each quart. C Á
1JCF
240 Hz, m-B(C6F5)3), 129.6, 129.5, 126.5, 126.2,
125.2 (2ꢃ) (each Ph), 125.4, 105.8 (pyrrol), 118.7 (C2),
78.7 (C3), 59.0 (C1), 30.4, 30.1, 29.9, 29.6 (each i-PrÁ
CH), 24.9, 24.4, 23.8, 23.6, 23.3, 23.2, 23.0, 22.7 (each i-
PrÁ
CH3), 15.4 (C4). 19F-NMR (599.9 MHz, benzene-d6,
298 K): dꢂ 130.7 (m, 6F, o-B(C6F5)3), ꢁ157.2 (t, 3F,
p-B(C6F5)3), -163.1 (m, 6F, m-B(C6F5)3). 11B{1H}-
ꢂ
/
235 Hz, p-B(C6F5)3), 139.6, 139.4,
/
CH(CH3)2), 136.7 (dm,
ꢂ
/
3.6. Protonation of 4b with the (2H-pyrrol)/B(C6F5)3
adduct 8, formation of E-9b
/
/
/
/
ꢁ
/
/
3.6.1. NMR experiments
Complex E-9b was in situ generated by the slow
dropwise addition of a solution of 18.9 (32.6 mmol) of 8 in
0.4 ml of CD2Cl2 to a solution of 20.0 mg (32.6 mmol) of
complex 4b in 0.4 ml of CD2Cl2. Only the isomer E-9a was
detected by NMR spectroscopy.
NMR (64.2 MHz, benzene-d6, 298 K): d ꢂ
(KBr): n˜
(vs), 1277 (w), 1088 (m), 980 (m), 760 (w) cmꢁ1
/
ꢁ
/
8.2. IR
/
ꢂ2968 (m), 2870 (w), 1644 (m), 1516 (s), 1462
/
.
3.7. Reaction of 4a with [Ph3Cꢀ][B(C6F5)4ꢁ] (11),
formation of Z-12a
3.6.2. Preparation of E-9b
3.7.1. NMR experiments
The reaction of 8 (189 mg, 326 mmol) with 4b (200 mg,
326 mmol) was carried out at 0 8C in 40 ml CH2Cl2
analogously as described above. After stirring for 4 h at
ambient temperature and the usual work-up 316 mg
(81%) of the product E-9b was obtained, m.p. 212 8C
(dec.). Anal. Calc. for C62H51BF15N3Ni (M 1192.6): C,
62.44; H, 4.31; N, 3.52. Found: C, 62.25; H, 4.51; N,
3.26%.
Complex Z-12a was in situ generated by adding a
solution of 4a (53.5 mg, 58.0 mmol) in 0.5 ml CD2Cl2 to
a solution of 30.0 mg (58 mmol) of 11 in CD2Cl2 at
ambient temperature. The brownÁviolet solution was
/
used to characterize the product by NMR spectroscopy;
only the signals of Z-12a were observed.
3.7.2. Prepraration of Z-12a
A mixture of the reagents 11 (535 mg, 580 mmol) and
4a (300 mg, 580 mmol) were placed in a Schlenk flask.
1H-NMR (599.9 MHz, CD2Cl2, 298 K): dꢂ
/
8.19 (d,
8.0 Hz,
napht.), 7.54 (m, 2H, Ph), 7.48-7.44 (m, 4H, Ph), 6.80,
3
3
2H, JHH
ꢂ
/
8.0 Hz, napht.), 7.57 (t, 2H, JHH
ꢂ
/
Pre-cooled (ꢁ
/
78 8C) dichloromethane (40 ml) was
6.78 (each d, each 1H, 3JHH
ꢂ8.0 Hz, napht.), 6.57, 5.88
/
added. The mixture was stirred for 30 min at ꢁ
/
78 8C,
(each s, each 2H, pyrrol), 5.53 (d t, 1H, 3JHH
ꢂ
/
13.3 Hz,
then allowed to warm to r.t. and stirred for further 4 h.
Solvent was removed in vacuo and the residue sus-
3JHH
ꢂ/7.1 Hz, 2-H), 3.66 (sept, 1H, JHH
ꢂ/6.8 Hz, i-
3

258
J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á260
/
pended in pentane (30 ml). The resulting solid was
collected by filtration, washed with pentane (3ꢃ10 ml)
3.8. Reaction of [Ph3Cꢀ][B(C6F5)4ꢁ] (11) with 4b,
formation of Z-12b
/
and dried in vacuo to yield 634 mg (76%) of Z-12a, m.p.
243 8C. Anal. Calc. for C75H61BF20N2Ni (M 1439.8): C,
62.57; H, 4.27; N, 1.95. Found: C, 63.07; H, 4.65; N,
1.85%.
3.8.1. NMR experiments
For the NMR spectroscopic characterization Z-12b
was generated in situ by slowly adding a solution of 11
(45.1 mg, 48.9 mmol) in 0.5 ml CD2Cl2 to a solution of
4b (30.0 mg, 48.9 mmol) in 0.5 ml CD2Cl2. Only the
formation Z-12b isomer was observed.
3.8.2. Preparation of Z-12b
Analogously as described above 11 (150 mg, 245
mmol) and 4b (226 mg, 245 mmol) were reacted at
ꢁ78 8C in dichloromethane (30 ml). The mixture was
/
warmed to room temperature during 2 h and then
stirred for 6 h. Work-up as described above yielded 300
mg (80%) of Z-12b, m.p. 245 8C. Anal. Calc. for
C83H61BF20N2Ni (M 1535.9): C, 64.91; H, 4.00; N,
1.82. Found: C, 64.58; H, 4.12; N, 1.99%.
1H-NMR (599.9 MHz, CD2Cl2, 298 K): dꢂ
/
7.65 (t,
3
1H, JHH
3
7.8 Hz, p-Ph), 7.56 (d, 1H, JHH
ꢂ
/
ꢂ
/
7.8 Hz,
3
m-Ph), 7.50 (d, 1H, JHH
ꢂ7.8 Hz, m-Ph), 7.36 (t, 1H,
/
3JHH
Ph), 7.28 (d, 1H, JHH
9H, o- and p-CPh3), 6.83Á
(dt, 1H, 3JHH 15.0 Hz, 3JHH
1H, 3JHH 12.7 Hz, 3JHH 8.2 Hz, 2JHH
3-H), 3.38, 3.03, 3.02, 2.56 (each sept, each 1H, JHH
ꢂ
/
7.8 Hz, p-Ph), 7.32 (d, 1H, JHH
ꢂ
/
7.8 Hz, m-
7.8 Hz, m-Ph), 7.16Á7.12 (m,
6.81 (m, 6H, m-CPh3), 5.18
8.2 Hz, 2-H), 3.61 (ddd,
3.5 Hz, 1H,
3
3
ꢂ
/
/
/
ꢂ
/
ꢂ
/
ꢂ
/
ꢂ
/
ꢂ
/
3
ꢂ
/
2
6.8 Hz, i-PrÁ
2JHH
3.5 Hz, 4?-H), 2.40 (dd, 1H, JHH
2JHH
1.6 Hz, 1syn-H), 2.18, 2.11 (each s, each 3H, NC-
CH3), 1.96 (dd, 1H, JHH
1anti-H), 1.64 (t, 1H, JHH
1.34, 1.26, 1.22, 1.20, 1.17, 1.12 (each d, each 3H,
3JHH CH3). 13C{1H}-NMR (150.8 MHz,
6.8 Hz, i-PrÁ
CD2Cl2, 298 K): dꢂ177.2, 176.7 (each C ꢀN), 148.5
250 Hz, o-B(C6F5)4), 145.5 (ipso-CPh3),
/
CH), 2.60 (dd, 1H, JHH
ꢂ
/
12.7 Hz,
3
ꢂ
/
ꢂ
/
8.2 Hz,
ꢂ
/
3
2
ꢂ
ꢂ
/
15.0 Hz, JHH
ꢂ1.6 Hz,
/
/
12.9 Hz, 4-H), 1.67, 1.44,
1H-NMR (599.9 MHz, CD2Cl2, 298 K): dꢂ
/
/
8.20 (d,
7.8 Hz,
7.8 Hz, p-Ph), 7.65 (dd, 2H,
1.2 Hz, m-Ph), 7.59 (t, 1H,
3
1H, 3JHH
ꢂ
/
7.8 Hz, napht.), 8.19 (d, 1H, JHH
ꢂ
ꢂ
/
/
napht.), 7.77 (t, 1H, 3JHH
ꢂ
/
/
/
1
4
7.8 Hz, JHH
3JHH
3JHH
ꢂ
/
ꢂ
/
(dm, JCF
143.2, 143.0 (ipso-Ph), 138.6 (dm, JCF
B(C6F5)4), 139.0, 138.1, 137.9, 137.3 (each quart. C Á
ꢂ
/
1
3
ꢂ250 Hz, p-
/
ꢂ
/
7.8 Hz, napht.), 7.56 (t, 1H, JHH
ꢂ
/
7.8 Hz,
7.8 Hz, p-Ph), 7.44 (dd, 2H,
1.2 Hz, m-Ph), 7.39 (dd, 1H,
1.2 Hz, m-Ph), 7.18Á7.14 (m,
6.81 (m, 6H, m-CPh3), 6.77
napht.), 7.48 (t, 1H, 3JHH
ꢂ
/
/
1
4
7.2 Hz, JHH
3JHH
3JHH
ꢂ
/
ꢂ
/
CH(CH3)2), 136.7 (dm, JCF
ꢂ250 Hz, m-B(C6F5)4),
/
4
129.1, 128.4, 126.7 (o-, m- and p-Ph-CPh3), 129.7, 129.3,
125.8, 125.6, 125.1, 124.9 (each Ph), 116.1 (C2), 76.9
(C3), 60.4 (C1), 58.1 (CPh3), 39.1 (C4), 30.6, 30.2, 29.7,
ꢂ
/
7.2 Hz, JHH
ꢂ
/
/
9H, o- und p-CPh3), 6.83Á
/
3
3
(d, 1H, JHH
Hz, napht.), 5.42 (dt, 1H, JHH
Hz, 2-H), 3.82 (ddd, 1H, 3JHH 12.8 Hz, 3JHH
3JHH
ꢂ
/
7.8 Hz, napht.), 6.74 (d, 1H, JHH
ꢂ/7.8
3
3
29.2 (each i-PrÁ
23.2, 22.8 (each i-PrÁ
19F-NMR (599.9 MHz, benzene-d6, 298 K): dꢂ
(m, 6F, o-B(C6F5)3), ꢁ164.3 (t, 3F, p-B(C6F5)3),
168.1 (m, 6F, m-B(C6F5)3). 11B{1H}-NMR (64.2
MHz, benzene-d6, 298 K): dꢂ 14.9. IR (KBr): n˜
/
CH), 24.9, 24.8, 24.0, 23.9, 23.7, 23.5,
CH3), 20.8, 20.0 (each NCÁCH3).
133.6
ꢂ/15.6 Hz, JHH
ꢂ/8.1
/
/
ꢂ
/
ꢂ
/8.1 Hz,
/
ꢁ
/
ꢂ
/
3.3 Hz, 1H, 3-H), 3.58, 3.43, 3.34, 3.01 (each
3
/
sept, each 1H, JHH
ꢂ
/
6.8 Hz, i-PrÁ
3.3 Hz, 4?-H), 2.73 (dd, 1H,
1.6 Hz, 1syn-H), 2.33 (dd, 1H,
1.6 Hz, 1anti-H), 1.84 (t, 1H,
/CH), 2.76 (dd, 1H,
3
12.8 Hz, JHH
2JHH
3JHH
3JHH
ꢂ
/
ꢂ
/
ꢁ
/
2
8.1 Hz, JHH
/
ꢁ
/
/
ꢂ
/
ꢂ
/
ꢂ
/
2
15.6 Hz, JHH
3063 (w), 2971 (s), 2932 (m), 2874 (w), 1644 (s), 1515
(vs), 1466 (vs), 1381 (s), 1277 (m), 1088 (vs), 980 (vs), 722
ꢂ
/
ꢂ
/
JHH
1.00, 0.96 (each d, each 3H, JHH
ꢂ12.8 Hz, 4-H), 1.69, 1.54, 1.30, 1.28, 1.14, 1.02,
/
3
(s) cmꢁ1
.
ꢂ
/
ꢁ
/
6.8 Hz, i-PrÁ
/

J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á
/260
259
CH3). 13C{1H}-NMR (150.8 MHz, CD2Cl2, 298 K):
dꢂ173.7, 172.8 (each C ꢀ 240 Hz,
N), 148.5 (dm, 1JCF
o-B(C6F5)4), 145.6 (ipso-CPh3), 143.0, 142.9 (ipso-Ph),
References
/
/
ꢂ
/
[1] P.W. Jolly, G. Wilke, The Organic Chemistry of Nickel, vol. I,
1974, vol. II 1975, Academic Press, New York.
[2] (a) G. Wilke, Angew. Chem. 75 (1963) 10;
1
138.6 (dm, JCF
138.0, 137.6 (each quart. C Á
1JCF
240 Hz, m-B(C6F5)4), 133.8, 133.6, 130.0, 129.9,
ꢂ/240 Hz, p-B(C6F5)4), 139.6, 138.7,
/CH(CH3)2), 136.6 (dm,
(b) G. Wilke, B. Bogdanovic, P. Hardt, P. Heimbach, W. Keim,
ꢂ
/
M. Kroner, W. Oberkirch, K. Tanaka, E. Steinrucke, D. Walter,
¨
¨
H. Zimmermann, Angew. Chem. 78 (1966) 157; Angew. Chem.
Int. Ed. Engl. 5 (1966) 151;
126.1, 126.0 (napht.), 129.8, 129.5, 129.4, 126.3, 125.3
(each Ph), 129.1, 128.4, 126.8 (o-, m- und p-CPh3), 115.6
(C2), 75.5 (C3), 60.3 (C1), 57.9 (CPh3), 39.2 (C4), 30.5
(c) B. Bogdanovic, Adv. Organomet. Chem. 17 (1979) 105.
[3] (a) S. Svejda, L.K. Johnson, M. Brookhardt, J. Am. Chem. Soc.
121 (1999) 10634;
(2x), 30.0, 29.6 (each i-PrÁ
23.9, 23.6, 23.4, 22.8 (each i-PrÁ
MHz, benzene-d6, 298 K): dꢂ
B(C6F5)3), ꢁ163.9 (t, 3F, p-B(C6F5)3), ꢁ
m-B(C6F5)3). 11B{1H}-NMR (64.2 MHz, benzene-d6,
298 K): dꢂ 14.5. IR (KBr): n˜ 3067 (w), 2967 (vs),
/
CH), 25.4, 24.7, 24.1, 23.9,
CH3). 19F-NMR (599.9
133.1 (m, 6F, o-
168.0 (m, 6F,
/
(b) D.P. Gates, S.K. Svejda, E. Onate, C.M. Killian, L.K.
Johnson, P.S. White, M. Brookhart, Macromolecules 33 (2000)
2320;
/
ꢁ
/
/
/
(c) For recent articles see, e.g.: T.R. Younkin, E.F. Connor, J.I.
Henderson, S.K. Friedrich, R.H. Grubbs, D.A. Bansleben,
Science 287 (2000) 460;
/
ꢁ
/
/
ꢂ
/
2932 (m), 2874 (m), 1644 (s), 1612 (s), 1512 (vs), 1462
(vs), 1273 (s), 1088 (vs), 996 (vs), 776 (s) cmꢁ1
(d) W. Liu, J.M. Malinoski, M. Brookhart, Organometallics 21
(2002) 2836;
.
(e) R.J. Maldanis, J.S. Wood, A. Chandrasekaran, M.D. Rausch,
J.C.W. Chien, J. Organomet. Chem. 645 (2002) 158;
(f) D. Zhang, G.-X. Jin, N. Hu, Chem. Commun (2002) 574;
3.9. Ethene polymerization
(g) D.L. Schroder, W. Keim, M.A. Zuideveld, S. Mecking,
¨
Macromolecules 35 (2002) 6071;
(h) P. Preishuber-Pflugl, M. Brookhart, Macromolecules 35
(2002) 6074;
A 1-l thermostated glass autoclave (Buchi) was
¨
charged with 200 ml of dry toluene under argon.
Triisobutylaluminum (0.5 ml) was added. The solution
was then saturated with ethene at 2 bar with rapid
stirring (700 U minꢁ1) at 25 8C. After 45 min the
polymerization reaction was started by injection of a
solution of ca. 35 mmol of the nickel catalyst in 10 ml
toluene. After a reaction time of 1 h the mixture was
quenched by adding 10 ml of a 1:1 mixture of methanol
and 2 N aqueous HCl. After 20 min stirring and
evaporation of excess ethene the formed polyethylene
product was precipitated by adding 100 ml of methanol.
The polymer was collected by filtration, washed with 2
(i) Y.H. Kim, T.H. Kim, B.Y. Lee, D. Woodmansee, X. Bu, G.C.
Bazan, Organometallics 21 (2002) 3082.
[4] (a) A.G. Massey, A.J. Park, F.G.A. Stone, Proc. Chem. Soc.
Lond. (1963) 212;
(b) A.G. Massey, A.J. Park, J. Organomet. Chem. 2 (1964) 245;
(c) A.G. Massey, A.J. Park, in: R.B. King, J.J. Eisch (Eds.),
Organometallic Synthesis, vol. 3, Elsevier, New York, 1986, p.
461.
[5] B. Temme, G. Erker, J. Karl, H. Luftmann, R. Frohlich, S.
¨
Kotila, Angew. Chem. 107 (1995) 1867; Angew. Chem. Int. Ed.
Engl. 34 (1995) 1755.
[6] (a) D.D. Devore, F.J. Timmers, D.L. Hasha, R.K. Rosen, T.J.
Marks, P.A. Deck, C.L. Stern, Organometallics 14 (1995) 3132;
(b) G.J. Pindado, M. Thornton-Pett, M. Bochmann, J. Chem.
Soc. Dalton Trans. (1997) 3115;
N aqueous HCl, water and acetone (each 3ꢃ50 ml) and
/
then dried over night at 50 8C in vacuo. For the
characterization by 13C-NMR spectroscopy (90.6
MHz) the respective polymer samples (ca. 60 mg) were
dissolved in toluene-d8 with heating, and the 13C-NMR
spectra recorded at 353 K. The typical NMR spectra of
branched polyethylene were obtained [8,25]. The mole-
cular weights and polydispersities of the polyethylene
samples were obtained by GPC using an Agilent Series
1100 refractive index detector. The gel permeation
chromatography was carried out in THF at 35 8C using
(c) J. Karl, G. Erker, R. Frohlich, J. Organomet. Chem. 535
¨
(1997) 59;
(d) A.H. Cowley, G.S. Hair, B.G. McBurnett, R.A. Jones, J.
Chem. Soc. Chem. Commun (1999) 437;
(e) M. Dahlmann, G. Erker, M. Nissinen, R. Frohlich, J. Am.
¨
Chem. Soc. 121 (1999) 2820;
(f) M. Dahlmann, G. Erker, R. Frohlich, O. Meyer, Organome-
¨
tallics 19 (2000) 2956;
(g) M. Dahlmann, G. Erker, K. Bergander, J. Am. Chem. Soc.
122 (2000) 7986.
[7] (a) Reviews: G. Erker, Acc. Chem. Res. 34 (2001) 309;
(b) G. Erker, Chem. Commun (2003) 1469.
[8] Preliminary communication: J. Strauch, G. Erker, G. Kehr, R.
˚
two columns (100.000 and 1.000 A). The Mn values
listed in Table 2 are relative to a polystyrene standard.
Frohlich, Angew. Chem. 114 (2002) 2662; Angew. Chem. Int. Ed.
¨
Engl. 41 (2002) 2543.
[9] L.K. Johnson, C.M. Killian, M. Brookhart, J. Am. Chem. Soc.
117 (1995) 6114.
[10] (a) G.J.P. Britosek, V.C. Gibson, D.F. Wass, Angew. Chem. 111
(1999) 448; Angew. Chem. Int. Ed. Engl. 38 (1999) 428;
(b) S.D. Ittel, L.K. Johnson, M. Brookhart, Chem. Rev. 100
(2000) 1169.
Acknowledgements
Financial support from the Fonds der Chemischen
Industrie and the Deutsche Forschungsgemeinschaft are
gratefully acknowledged.
[11] (a) H. tom Dieck, M. Svoboda, T. Greiser, Z. Naturforsch. Teil b
36 (1980) 823;
(b) J.C.M. Sinnema, G.H.B. Fendesak, H. tom Dieck, J.

260
J.W. Strauch et al. / Journal of Organometallic Chemistry 683 (2003) 249Á260
/
Organomet. Chem. 390 (2002) 237;
(c) J.C.M. Sinnema, H. tom Dieck, G. Fendesak, J. Organomet.
Chem. 397 (1990) 261.
[17] (a) See also: M. Hill, G. Kehr, R. Frohlich, G. Erker, Eur. J.
¨
Inorg. Chem. (2003) in press;
(b) L. Resconi, Personal communication.
[12] (a) H.E. Ramsden, US Patent (1968) 3388179;
(b) Y. Nakano, K. Natsukawa, H. Yasuda, H. Tani, Tetrahedron
Lett. (1972) 2833;
[18] (a) S.H. Strauss, Chem. Rev. 93 (1993) 927;
(b) E.Y.-X. Chen, T.J. Marks, Chem. Rev. 100 (2000) 1391.
[19] E.G. Hoffmann, R. Kallweit, G. Schroth, K. Seevogel, W.
Stempfle, G. Wilke, J. Organomet. Chem. 97 (1975) 183.
[20] J.C.W. Chien, W.-M. Tsai, M.D. Rausch, J. Am. Chem. Soc. 113
(1991) 8570.
(c) K. Fujita, Y. Ohnuma, H. Yasuda, H. Tani, J. Organomet.
Chem. 113 (1976) 201;
(d) H. Yasuda, Y. Nakano, K. Natsukawa, H. Tani, Macro-
molecules 11 (1978) 586;
[21] (a) T.M. Kooistra, Q. Knijnenburg, J.M.M. Smits, A.D. Horton,
P.H.M. Budzelaar, A.W. Gal, Angew. Chem. 113 (2001) 4855;
Angew. Chem. Int. Ed. Engl. 40 (2001) 4719;
(e) Y. Kai, N. Kanehisa, K. Miki, N. Kasai, K. Mashima, H.
Yasuda, A. Nakamura, Chem. Lett (1982) 1277;
(f) See also: S. Datta, S.S. Wreford, R.P. Beatty, T.J. McNeese, J.
Am. Chem. Soc. 101 (1979) 1053;
(b) V.C. Gibson, M.J. Humphries, K.P. Tellmann, D.F. Wass,
A.J.P. White, D.J. Williams, Chem. Commun. (2001) 2252.
[22] J. Cano, P. Royo, M. Lanfranchi, M.A. Pellinghelli, A. Tiripic-
chio, Angew. Chem. 113 (2001) 2563; Angew. Chem. Int. Ed.
Engl. 40 (2001) 2495.
(g) S.S. Wreford, J.F. Whitney, Inorg. Chem. 20 (1981) 3918.
[13] (a) For examples of the use of the butadiene-magnesium reagent
in organometallic synthesis see, e.g. H. Yasuda, Y. Kajihara, K.
Mashima, K. Nagasuna, K. Lee, A. Nakamura, Organometallics
1 (1982) 388;
[23] J. Jin, D.R. Wilson, E.Y.-X. Chen, Chem. Commun. (2002) 708.
[24] T. Usami, S. Takayama, Macromolecules 17 (1984) 1756.
[25] (a) D.E. Axelson, G.C. Levy, L. Mandelkern, Macromolecules 12
(1979) 41 (and references cited therein);
(b) Reviews: H. Yasuda, K. Tatsumi, A. Nakamura, Acc. Chem.
Res. 18 (1985) 120;
(c) G. Erker, C. Kruger, G. Muller, Adv. Organomet. Chem. 24
(b) E.T. Hsieh, J.C. Randall, Macromolecules 15 (1982) 353;
(c) G.B. Galland, R.F. de Souza, R.S. Mauler, F.F. Nunes,
Macromolecules 32 (1999) 1620;
¨
¨
(1985) 1;
(d) H. Yasuda, A. Nakamura, Angew. Chem. 99 (1987) 745;
Angew. Chem. Int. Ed. Engl. 26 (1987) 723.
(d) A. Jurkiewicz, N.W. Eilerts, E.T. Hsieh, Macromolecules 32
(1999) 5471.
[26] D. Vagedes, G. Erker, R. Frohlich, J. Organomet. Chem. 641
¨
[14] G. Erker, K. Berg, R. Benn, G. Schroth, Angew. Chem. 96 (1984)
621; Angew. Chem. Int. Ed. Engl. 23 (1984) 625.
[15] G. Kehr, R. Frohlich, B. Wibbeling, G. Erker, Chem. Eur. J. 6
¨
(2002) 148.
(2000) 258.
[16] G. Kehr, R. Roesmann, R. Frohlich, C. Holst, G. Erker, Eur. J.
¨
[27] S. Braun, H.-O. Kalinowski, S. Berger, 150 and More Basic NMR
Experiments (and references cited therein), VCH, Weinheim, 1998
(and references cited therein).
Inorg. Chem. (2001) 535.