Conversion of imine ligands in allyl-nickel(II) complexes

Article abstract of DOI:10.1016/j.jorganchem.2009.08.010

Interaction of Ni(allyl)₂ and bidentate nitrogen-containing ligands (phenanthroline-1,10; bis(2,6-diisopropylphenyl)diazabutadiene) has been studied. It has been shown that coordination of diimine ligands proceeds with transfer of an allylnickel group to the diimine frame and formation of a covalent Ni-N bond giving rise to imine(amide)Ni(II) complexes. In the case of phenanthroline dearomatization of one heteroaromatic ring takes place. The low-spin imine(amide)allyl complexes (allyl)Ni(C₁₅H₁₅N₂) (1) and (allyl)Ni(C₂₉H₄₂N₂) (3) have been isolated as crystals and characterized by solution spectroscopy. Combining two molar equivalents of phenanthroline-1,10 with Ni(allyl)₂ results in the transfer of both allyl groups and formation of the high-spin imine(amide)Ni(II) complex Ni(C₁₅H₁₅N₂)₂ (2).

Full text of DOI:10.1016/j.jorganchem.2009.08.010

Journal of Organometallic Chemistry 694 (2009) 3912–3917
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Conversion of imine ligands in allyl–nickel(II) complexes
a
b
c
Peter B. Kraikivskii a,b, , Hans-Friedrich Klein , Vitaly V. Saraev , Reinhard Meusinger ,
*
Ingrid Svoboda d, Mikhail Pashchanka a
a Eduard-Zintl-Institut für Anorganische und Physikalische Chemie der Technischen Universität Darmstadt, Petersenstrasse 18, 64287 Darmstadt, Germany
b Department of Chemistry, Irkutsk State University, Str. K. Marksa, 1, Irkutsk 664003, Russia
c Clemens-Schoepf-Institut für Organische Chemie und Biochemie der Technischen Universität Darmstadt, Petersenstrasse 22, 64287 Darmstadt, Germany
d Fachgebiet Strukturforschung, Fachbereich Material – und Geowissenschaften der Technischen Universität Darmstadt, Petersenstrasse 23, 64287 Darmstadt, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Interaction of Ni(allyl)2 and bidentate nitrogen-containing ligands (phenanthroline-1,10; bis(2,6-diiso-
propylphenyl)diazabutadiene) has been studied. It has been shown that coordination of diimine ligands
proceeds with transfer of an allylnickel group to the diimine frame and formation of a covalent Ni–N
bond giving rise to imine(amide)Ni(II) complexes. In the case of phenanthroline dearomatization of
one heteroaromatic ring takes place. The low-spin imine(amide)allyl complexes (allyl)Ni(C15H15N2) (1)
and (allyl)Ni(C29H42N2) (3) have been isolated as crystals and characterized by solution spectroscopy.
Combining two molar equivalents of phenanthroline-1,10 with Ni(allyl)2 results in the transfer of both
allyl groups and formation of the high-spin imine(amide)Ni(II) complex Ni(C15H15N2)2 (2).
Ó 2009 Elsevier B.V. All rights reserved.
Received 19 June 2009
Accepted 5 August 2009
Available online 12 August 2009
Keywords:
Nickel
Diimine ligands
Chelates
Structure elucidation
1. Introduction
on these intriguing problems we have studied the reaction of
bis(allyl)nickel with phenanthroline-1,10 and bis(2,6-diisopropyl-
Dimerization and polymerization of olefins are among the most
important industrial processes nowadays. Neutral and cationic
complexes of nickel are applied in highly effective homogeneous
processes of ethylene oligomerization, such as SHOP-process [1–
4]. Comparatively recently it has been shown that bidentate dii-
mine nickel complexes can catalyze conversions of low olefins into
products of different polymerization degree ranging from dimers
to high molecular weight polymers [5]. Of special importance is
that diimine nickel complexes may be useful for manufacture of
phenyl)diazabutadiene which can be ranked as classic ligands of
Brookhart catalysts. These systems were chosen because they con-
tain nickel complexes bearing an olefin unit bound to the metal
atom and an imine ligand within the coordination sphere. In par-
ticular, phenanthroline and bis(2,6-diisopropylphenyl)diazabut-
adiene enable us to assess the behavior of a nitrogen donor atom
either integrated in an aromatic system or positioned beyond it.
2. Results and discussion
a-olefinic products [6–8].
Diimine ligands allow an extensive varying both the geometric
Addition of one mole equivalent of phenanthroline-1,10 to an
ether solution of Ni(allyl)2 at ꢀ5 °C makes the yellow solution turn
bright green (Eq. (1)). Raising the temperature to 35 °C leaves the
coloration unaltered. Evaporation of the volatiles in vacuo gave a
green powder which was readily soluble in pentane, benzene, or
tetrahydrofurane. Recrystallization from pentane yielded filar crys-
tals which decomposed in air within 10–15 min.
and donor–acceptor properties of catalytically active complexes
and thereby a control over properties of the prepared catalysts
[9–18]. This gave a great impetus to syntheses of a wealth of
new diimine ligands and their metallo-complexes with different
transition metals [19–32].
One of the poorest known issues, in our view, is the possibility
for imine ligands to be converted within the coordination sphere of
a transition metal in the course of catalytic cycle. Is the structure of
a nitrogen ligand left intact over the whole life of the catalytically
active species? Does the nature of the nitrogen–metal bond alter in
the course of the catalyst functioning? In order to shed more light
+
Ni
N
N
N
N
Ni
1
* Corresponding author. Address: Department of Chemistry, Irkutsk State
University, Str. K. Marksa, 1, Irkutsk 664003, Russia. Tel.: +49 6151 162173.
E-mail address: peter10@list.ru (P.B. Kraikivskii).
ð1Þ
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.08.010

P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 694 (2009) 3912–3917
3913
For the assignment of the confusing 1H and 13C NMR spectra of
complex 1 heteronuclear multiple bond coherence methods were
applied. The 1H NMR spectrum of complex 1 shows a clear signal
at 5.87 ppm which is representative for an allyl group bound to
nickel. The signal is displaced to a weak field by comparison with
that from the complex Ni(allyl)2 (4.98 ppm). In the HSQC spectrum
the signal at 5.87 ppm shows a cross-peak with the 13C signal at
112.65 ppm which is slightly displaced to a strong field relative
to that from the complex Ni(allyl)2 (112.91 ppm). All the four pro-
tons in the CH2-groups of the allyl moiety at the nickel atom are
non-equivalent (d = 2.14, 2.57, 2.78, 3.09 ppm) and generally more
shielded in comparison with those in Ni(allyl)2 (1.75, 3.09 ppm)
[33,34]. The proton signals show cross-peaks with 13C nuclei at
51.32 and 54.90 ppm. Quantitative 1H and 13C NMR spectra detect
the complex 1 as two isomers, different in the position of the allyl
groups, only. The isomers ratio is about 1:1.15. An independence of
the ratio from the used solvent was observed in benzene, toluene
and in tetrahydrofurane. The difference in the intensities allowed
the assignment of all NMR signals to particular isomers. In 1967
Wilke and co-workers [33] reported that Ni(allyl)2 exists in the
form of dynamically equilibrated cis- and trans-isomers differing
by the locations of the allyl moieties. The ratio between these iso-
mers depends strongly on the temperature and ranges from 3:1 at
+30 °C to 8:1 at ꢀ70 °C. Quantitative NMR spectroscopy was ap-
plied from 60 °C up to ꢀ83 °C to elucidate the possibility of the
transformation between the cis- and trans-isomers of complex 1.
However, the ratio of the cis-, trans-isomers was constant in the
temperature range. It is noteworthy that both the intensities and
the ratio between the signals of the cis- and trans-isomers left con-
stant for at least two months when a solution was kept in a sealed
NMR ampoule. This fact suggests a rather high energy barrier for
the interconversion of the cis- and trans-forms of the complex.
The presence of two isomers may testify that the formation of com-
plex 1 proceeds at two reaction centers or according to two differ-
ent mechanisms.
Fig. 1. Molecular structure of 1 (ORTEP plot with hydrogen atoms omitted); distances
between selected atoms [Å] and angles [°]: Ni–N1 = 1.921(3), Ni–N2 = 1.896(3), Ni–
C17 = 1.969(6), N1–C1 = 1.325(4), N1–C12 = 1.372(4), C1–C2 = 1.383(5), N2–C10 =
1.469(5), N2–C11 = 1.329(5), C10–C9 = 1.505(6), N1–Ni–N2 = 85.14(12), N2–Ni–
C18 = 100.97 (16), N1–Ni–C17 = 133.6(3), N2–Ni–C17 = 136.3(2), Ni–N2–C11 =
112.5(2), Ni–N1–C12 = 111.5(2).
complex as a whole. To the best of our knowledge, no reaction
associated with a similarly profound altering of an aromatic het-
erocyclic ligand has been described. We reason that if the ligands
of the catalytically active species undergo such dramatic change
in both the electronic and geometric structures, it must crucially
affect the course of catalysis.
N
N
Ni
1
+
The IR spectrum of complex 1 displays a significant displace-
ment of the skeleton vibration bands of phenanthroline rings in
the region of 1637–1322 cmꢀ1 together with the appearance of
new intensive narrow lines at 904 and 846 cmꢀ1 attributable to
the vibrations of a dearomatized nitrogen heterocycle. Further-
more, in the low-frequency IR region there appears a narrow line
at 291 cmꢀ1 which can be assigned to the Ni–N vibration [34].
The mass-spectrum of complex 1 has the molecular ion peak m/z
320 with a very low intensity (3.5%). It is quite explicable by a fac-
ile detachment of the allyl moiety from the nickel atom during the
ionization. It is also supported by a high intensity of the signal at
m/z 279 (M+ꢀC3H5). All the spectral data are in excellent agree-
ment with those of an X-ray analysis (Fig. 1).
N
N
N
N
2
N
N
N
2
+
Ni
Ni
N
N
N
2
ð2Þ
To test complex 1 for a possible introduction of the second phe-
Analysis of the X-ray data as a whole allows one to state that the
dearomatized moiety of the formed ligand is characterized by
elongation of the ring skeleton bonds (N2–C10 = 1.469 Å, N2–
C11 = 1.329 Å, C9–C10 = 1.505 Å) and a short Ni–N bond (N2–
Ni = 1.896 Å) that is recognized as a d-bond, whereas the N1–Ni
bond is close by its parameters to the usual diazadiene coordina-
tion. As suggested by solution spectroscopy one may assert that
the dearomatized moiety of the ligand contains a sp3-hybridized
nitrogen atom, whereas that of the aromatic part remains sp2-
hybridized.
Thus the obtained data support the mechanistic view that phe-
nanthroline reacts with Ni(allyl)2 by formally inserting the C@N
moiety into the Ni–C bond of the allyl complex. In the process
one of the N-heterocycles undergoes dearomatization which is at-
tended with the formation of a new five-membered metallocycle.
Noteworthy, this cycle comprises two Ni–N bonds of fundamen-
tally different character that may play an essential role in the elec-
tronic and geometric properties of the resulting amide-imine
nanthroline molecule we have carried out its reaction with one
mole equivalent of phenanthroline.
When phenanthroline was added to an ether solution of com-
plex 1 the color of the reaction mixture turned from bright green
to greenish-brown. A similar change can be seen when the reaction
proceeds in pentane, tetrahydrofurane, or benzene. Vacuum evap-
oration gave a greenish-brown powder which during recrystalliza-
tions gave no crystals suitable for X-ray analysis. The 1H NMR
spectrum of the compound contains very broad and grossly shifted
signals, whereas the 13C spectrum has no signals apart from those
of the solvent. Varying the concentration and solvents (THF, C6D6,
acetone, toluene, and pyridine) did not improve the resolution. The
product appears to be a paramagnetic material. Its EPR spectrum
contained no signals from both the powdered complex and its
solutions at 296–77 K. This may be explained by the high-spin
state of a tetrahedral d8-complex of Ni(II). The mass-spectrum does
not display the molecular ion that seems to result from a low sta-
bility of the complex and its decomposition in the course of the

3914
P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 694 (2009) 3912–3917
ionization. The peak at the maximum m/z (222) is assigned to the
molecular ion of the protonated ligand C15H15N2+. In the IR spec-
trum of complex 2 one can see lines located close to those of com-
plex 1 together with novel intensive narrow bands at 812 and
728 cmꢀ1 in the region expected of the dearomatized heterocycle
and at 1531, 1420 and 1405 cmꢀ1 in the region of the skeleton
vibrations of aromatic rings. In the low-frequency IR region of
Ni–N vibrations a broadened band appears at 238 cmꢀ1 that is
shifted toward lower frequencies, as compared with complex 1.
Clearly the IR spectrum contains a second set of bands which is
consistent with a tetrahedral structure of complex 2. Thus the sec-
ond phenanthroline unit is inserted into the second Ni–C allyl bond
to form a high-spin tetrahedral nickel(II) complex 2. We have also
prepared this complex by reacting Ni(allyl)2 with two mole equiv-
alents of phenanthroline (Eq. (2)).
When one mole equivalent of bis(2,6-diisopropylphenyl)diaz-
abutadiene was added to an ether solution of Ni(allyl)2 at 0–5 °C
the color of the reaction mixture turned from yellow to bright
red. Crystallization from pentane at ꢀ30 °C gave bright red plates
of complex 3 (Eq. (3)). The 1H NMR spectrum of complex 3 contains
the well resolved multiplet at 5.35 ppm from one proton which is
characteristic of the allyl group bound to nickel. The signal is some-
what displaced to a strong field relative to the analogous signal of
complex 1 and significantly displaced to a weak field relative to
that of Ni(allyl)2 (4.98 ppm) [33,34].
i-Pr
i-Pr
i-Pr
ð4Þ
N
N
3
Ni
i-Pr
Thus, complex 3 in solution (toluene, benzene, THF, ether, pen-
tane) undergoes a spontaneous isomerization into complex 4
which remains unaltered in solution for two months at least. The
isomerization of complex 3 is attributable to a thermodynamical
stabilization of complex 4 by conjugation of double bonds. From
reddish-brown solutions of complex 4 in pentane, benzene, or
THF a reddish-brown powder was obtained which was readily sol-
uble but failed to form crystals suitable for X-ray analysis.
Addition of bis(2,6-diisopropylphenyl)diazabutadiene to com-
plexes 3 and 4 does not cause a reaction. NMR spectra show no
change except for appearance of the signals from the free ligand.
According to NMR data the reaction of Ni(allyl)2 with two mole
equivalents of bis(2,6-diisopropylphenyl)diazabutadiene also gives
complexes 3 and 4 and free bis(2,6-diisopropylphenyl)diazabut-
adiene. These observations suggest that free diimine ligands do
not readily replace an imine-amide ligand at the nickel center.
The transformation of an imine ligand in the coordination
sphere of a transition metal proceeding through formal insertion
of a C@N moiety into the M–C bond was previously demonstrated
for organometallic complexes Zr(CH2Ph)4 and Hf(CH2Ph)4 when
combined with 2,5-bis(N-aryliminomethyl)pyrrole [23,35]. Alkyl-
ation of a diene in the reaction between diethyl zinc and bis(2,6-
diisopropylphenyl)diazabutadiene was also described to form an
imine(amide)ethylzinc complex [36]. Similar reactions of organo-
nickel complexes are without precedent.
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
+
N
N
Ni
N
N
Ni
3
Exemplifying two classic ligands in Brookhart-type catalytic
systems, we have demonstrated principal alterations of the ligand
molecule by dearomatization of the aromatic heterocycle and the
formation of imine(amide)nickel complexes. This reactivity of dii-
mine ligands is bound to affect catalytic cycles of nickel complexes
comprising Brookhart-type ligands. The observed dearomatization
of phenanthroline under ambient conditions provides access to
amide(allyl)nickel complexes and is of general interest in
synthesis.
ð3Þ
In the HSQC spectrum the signal at 5.35 ppm has the cross-peak
with the 13C signal at 106.39 ppm which is, in contrast to complex
1, significantly displaced to a strong field by comparison with that
of Ni(allyl)2 (112.91 ppm). All the four proton of the CH2-groups of
the allyl moiety at the nickel are non-equivalent (d = 1.4, 1.43, 1.58
and 1.61 ppm) and, in general, much less shielded compared to
those of complex 1. Hence it may be suggested that the ligand of
complex 3 exhibits generally more acceptor properties than the li-
gand of complex 1 does. The double bond position in the allyl moi-
ety of the nitrogen-containing ligand is uniquely determined by
the DEPT-135 signals at 119.48 ppm (H2C@), 132.44 ppm (HC@)
and 37.65 ppm (CH2). When compared with the free ligand the
3. Experimental section
3.1. General procedures and materials
IR spectrum of complex 3 has the m
(C@N)imine band at 1602 cmꢀ1
shifted by about 24 cmꢀ1 to low frequency which correlates quite
well with published data on coordination shifts in diimine ligands
[21].
Standard vacuum techniques were used in manipulations of
volatile and air-sensitive materials.
Infrared spectra were measured for specimens pressed in KBr
tablets under argon on an Infralum FT-801 FT spectrometer. Mass
spectra were obtained on a Varian MAT spectrometer.
1H and 13C NMR spectra were obtained from a Bruker AVANCE
500. Assignment of 13C and 1H signals was supported by APT, DEPT,
COSY, NOESY, TOCSY, HMQC, HSQC, HMBC spectra. Melting points
were measured in capillaries sealed under argon and are uncor-
rected. The elemental analysis of the complexes was performed
on a FLACH 1112 analyzer (EA series).
In the mass-spectrum of complex 3 the molecular ion peak at
m/z 516 is pronounced, whereas the peak at m/z 476 (M+ꢀC3H5)
has the highest intensity. This suggests a rather facile dissociation
of an allyl moiety from the nickel.
When a solution of complex 3 is kept at 20–25 °C for 4 h, the
bright red color of the solution turns reddish-brown. The process
is attended with the clear replacement of the initial DEPT 13C
NMR signals at 119.48 ppm. (H2C@), 132.44 ppm (HC@), and
37.65 ppm (CH2) of the allyl moiety with CH2-terminal group in
complex 3 by the signals at 19.27 ppm (from terminal CH3-group),
140.89 ppm (HC@), 124.10 ppm (HC@) of the propenyl moiety
with terminal CH3-group in complex 4 (Eq. (4)). The other parts
of complexes 3 and 4 remain similar and the NMR signals alter
insignificantly (see Section 3).
3.2. Crystal structure analysis
Selected crystals were kept under paraffin oil for protection
against humidity. For single crystal data collection the crystals
were placed in premounted Cryoloops from Hampton Research

P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 694 (2009) 3912–3917
3915
Table 1
Crystal data for compound 1.
5
6
7
4
1
3
8
Empirical formula
Formula mass
Crystal size (mm)
Crystal system
Space group
a (Å)
C18H18N2Ni
321.05
0.20 ꢁ 0.10 ꢁ 0.02
Monoclinic
P21/c
9.8871(4)
19.0290(10)
7.8769(4)
99.265(4)
1462.64(12)
4
2
9
11
12
1
N
N
14
10
b (Å)
c (Å)
Ni
13
16
18
15
b (°)
V (Å3)
17
Z
Dcalcd. (g/cm3)
1.458
1.320
Fig. 2. Numbering scheme of carbon atoms in 1.
l
(Mo K
a
) (mmꢀ1
)
Temperature (K)
Data collected range (°)
h
k
100(2)
3
6.26 (d, JHH = 9.64 Hz, 1H, CH6), 6.24 (m, 1H, CH8), 5.28 (dd,
4.7 P 2h P 52.74
ꢀ12 P h P 12
ꢀ23 P k P 22
ꢀ7 P l P 9
8586
2976 (Rint = 0.0483)
209
0.970
3JHH = 4.9 Hz, JHH = 9.65 Hz, 1H, CH9), 4.32(m, 1H, CH10), 2.34
(m, 1H, CH213), 2.57 (m, 1H, CH213’), 5.96 (m, 1H, CH14), 4.95
3
2
l
(m, 2H, CH215), 2.14 (d, JHH = 12.8 Hz, 1H, CH216), 2.78 (d,
Number of reflections measured
Number of unique data
Parameters
2JHH = 6.61 Hz, 1H, CH216’), 5.67 (m, 1H, CH17), 2.57 (d,
2JHH = 13.00 Hz,
1H,
CH218),
3.09
(dd,
3JHH = 3.09 Hz,
2JHH = 12.73 Hz, 1H, CH218’) ppm (Fig. 2).
Goodness-of-fit (GOF) on F2
13C NMR (125 MHz, [D8]THF, 297 K): d = 148.93 (d,
R1 [I P 2r(I)]
0.0426
0.0876
wR2 (all data)
1JCH = 180.6 Hz, C1), 138,22 (d, JCH = 161.26 Hz, C2), 121.51 (d,
1
1JCH = 157.74 Hz, C3), 130,93 (s, C4), 128.27 (d, JCH = 157.75 Hz,
1
1
C5), 105.22 (d, JCH = 168.22 Hz, C6), 116.67 (s, C7), 125.65 (d,
1JCH = 157.74 Hz, C8), 123.57 (d, JCH = 158.9 Hz, C9), 63.96 (C10),
1
and cooled down to 100 K, covered with a protecting oil film. Data
collection was performed using an Xcalibur diffractometer from
Oxford Diffraction, equipped with the Enhance source option and
155.77 (s, C11), 143.58 (s, C12), 49.56 (C13), 136.17 (C14),
1
116.37 (t, JCH = 154.26 Hz, C15), 48.42 (C16), 109.95 (d,
1JCH = 159.9 Hz, C17), 55.28 (C18) ppm (Fig. 2).
Isomer B (trans-isomer)
Sapphire CCD detector in u and
x-scan mode, respectively. The
structure was solved by direct methods using SHELXS und refined
using SHELXL-97. H atoms were added at idealized positions (see
Table 1).
The Ni(allyl)2 complex and bis(2,6-diisopropylphenyl)diazabut-
adiene were prepared according to [33,13], respectively. Phenan-
throline-1,10 and all the used solvents were purchased (Merck).
1H NMR (500 MHz, [D8]THF, 297 K): d = 8.31 (m, 1H, CH1), 7.95
3
(m, 1H, CH2), 7.14(m, 1H, CH3), 6.77(d, JHH = 3.48 Hz, 1H, CH5),
3
6.26 (d, JHH = 6.33 Hz, 1H, CH6), 6.28 (m, 1H, CH8), 5.29 (dd,
3JHH = 4.8 Hz, JHH = 9.67 Hz, 1H, CH9), 4.42(m, 1H, CH10), 2.14
3
(m, 1H, CH13), 2.34 (m, 1H, CH13’), 5.96 (m, 1H, CH14), 5.01 (m,
2
2H, CH215), 2.24 (d, JHH = 13.36 Hz, 1H, CH216), 2.89 (d,
2JHH = 6.75 Hz, 1H, CH216’), 5.87 (m, 1H, CH17), 3.10 (dd,
3.3. Synthesis of 1
3JHH = 7.18 Hz,
2JHH = 12.67 Hz,
1H,
CH218’),
2.51
(d,
2JHH = 13.10 Hz, 1H, CH218) ppm (Fig. 2).
A cold solution (ꢀ5 °C) of phenanthroline-1,10 (0.54 g, 3 mmol)
in 50 ml of diethyl ether was slowly, during 30 min, added by
drops to a vigorously stirred solution of Ni(allyl)2 (0.423 g, 3 mmol)
in 50 ml of diethyl ether keeping the temperature at ꢀ5 °C. The
resulting bright green reaction mixture was kept stirring at this
temperature for 2 h followed by filtration. The filtrate was evapo-
rated in vacuo to give a bright green powder. This was dissolved
in 20 ml of pentane and kept in at ꢀ30 °C for three days. Thin green
needles were formed that were filtered off at ꢀ30 °C and dried for
6 h at 10ꢀ2 mbar, 20 °C. The product is stable in argon but air-
sensitive.
13C NMR (125 MHz, [D8]THF, 297 K): d = 149.04 (d,
1JCH = 190.42 Hz, C1), 138,25 (d, JCH = 150.2 Hz, C2), 121.55 (d,
1
1JCH = 172.04 Hz, C3), 131,06 (s, C4), 128.31 (d, JCH = 148.58 Hz,
1
1
C5), 105.04 (d, JCH = 168.22 Hz, C6), 116.90 (s, C7), 125.87 (d,
1JCH = 156.7 Hz, C8), 123.59 (d, JCH = 159.3 Hz, C9), 62.82 (C10),
1
155.77 (s, C11), 143.84 (s, C12), 48.89 (C13), 136.04 (C14),
1
116.19 (t, JCH = 153.22 Hz, C15), 51.32 (C16), 112.65 (d,
1JCH = 160.16 Hz, C17), 54.90 (C18) ppm (Fig. 2).
3.4. Synthesis of 2
Yield 632 mg (1.9 mmol), 66%.
Decomp. 82–90 °C. Anal. Calc. for C18H18N2Ni (321.04): C, 67.34;
H, 5.65; N, 8.73; Ni, 18.28. Found: C, 67.50; H, 6.05; N, 8.93%.
A solution of phenanthroline-1,10 (0.36 g, 2 mmol) in 30 ml of
diethyl ether was slowly, during 30 min, added by drops to a vig-
orously stirred solution of 1 (0.642 g, 2 mmol) in 30 ml of diethyl
ether at 20 °C. The greenish-brown reaction mixture was kept stir-
ring for 2 h followed by filtration. The filtrate was evaporated to
give a greenish-brown powder. This was dissolved in 20 ml of pen-
tane-ether (5:1 v/v) at 20–25 °C. The solution was kept in a refrig-
erator at ꢀ30 °C for three days to obtain a greenish-brown
amorphous precipitate. This was filtered off at ꢀ30 °C and dried
in vacuum for 6 h at 10ꢀ2 mbar, 20 °C. The product is stable in ar-
gon but air-sensitive.
HRMS: C18H18N2Ni calculated
– 320.0823, measured –
320.0822.
HRMS: C15H13N2Ni (M+ꢀC3H5) calculated – 279.0432, measured
– 279.04223.
MS (70 eV): m/z (%) = 39(36.9), 58(45.7), 98(28.5), 140(53.2),
180(74.3), 238(100.0), 279(80.5), 320(3.5).
IR (KBr) cmꢀ1: 3407(vs), 3021(m), 2915(m), 1637(s), 1616(s),
1589(s), 1542(s), 1506(s), 1463(s), 1396(s), 1376(s), 1124(s),
989(vs), 904(s), 846(s), 804(s), 786(s), 728(d), 711(s), 673(s),
646(s), 291(Ni–N, s).
Yield 470 mg (0.94 mmol), 47%.
Isomer A (cis-isomer).
Decomp. 126 – 128 °C. Anal. Calc. for C30H26N4Ni (501.25): C,
71.88; H, 5.23; N, 11.18; Ni, 11.71. Found: C, 71.05; H, 5.52; N,
10.93%.
1H NMR (500 MHz, [D8]THF, 297 K): d = 8.31 (m, 1H, CH1), 7.94
3
(m,1H, CH2), 7.14(m, 1H, CH3), 6.75(d, JHH = 3.48 Hz, 1H, CH5),

3916
P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 694 (2009) 3912–3917
MS (70 eV): m/z (%) = 39(65.7), 50.0(51.4), 51(50.4), 63(61.2),
53.61(C17), 28.44(C18), 26.16(C19), 26.34(C20), 28.30(C21),
24.49(C22), 25.16(C23), 37.65(C24), 132.44(C25), 119.48(C26),
29.09(C27), 24.14(C28), 24.23(C29), 29.29(C30), 24.42(C31),
24.57(C32) ppm (Fig. 3).
180(100.0), 193(58.9), 207(36.7), 221(42.8).
IR (KBr) cmꢀ1: 3401(w), 3023(m), 2823(m), 1620(s), 1548(s),
1569(s), 1531(s), 1506(s), 1468(s), 1447(s), 1420 (s), 1405(s),
1390(s), 1362(s), 1316(s), 1236(s), 1198(s), 1122(s), 989(vs),
906(s), 844(s), 830(s), 812(s), 795(s), 770(s), 728(d), 686(s),
636(s), 238(Ni–N, w).
3.6. Synthesis of 4
(a) A solution of complex 3 (2.58 g, 5 mmol) in 100 ml of diethyl
ether was kept in a Schlenk flask at 20–25 °C for 5 h and then
evaporated to give a reddish-brown powder. This was dis-
solved in 50 ml of pentane and kept in a refrigerator at
ꢀ30 °C for five days to obtain an amorphous reddish-brown
precipitate which was filtered off and dried for 6 h at 10ꢀ2
mbar, 20 °C. The product is stable in argon but air-sensitive.
Yield 1.99 g (3.85 mmol), 77%. m.p. 97– 100 °C 60 – 65 °C. Anal.
Calc. for C32H46N2Ni (517.41): C, 74.28; H, 8.96; N, 5.41; Ni,
11.34. Found: C, 73.42; H, 8.05; N, 4.70%. MS (70 eV): m/z
(%) = 31(12.1), 41(29.8), 59(18.8), 74(30.0), 186(13.56),
228(43.4), 418(32.4), 434(40.7), 476(100.0), 516(65.2).IR
(KBr) cmꢀ1: 3052(m), 3012(s), 2960(s), 2923(s), 2865(s),
2740(m), 2688(s), 1932(s), 1913(s), 1872(s), 1847(s), 1812(s),
1783(s), 1762(s), 1641(N@C, s), 1490(s), 1384(d), 1313(vs),
1253(s), 1218(s), 1205(s), 1076(vs), 987(vs), 919(s), 873(s),
794(s), 754(d), 568(s), 532(s).1H NMR (500 MHz, [D8]THF,
297 K): d = 6.94 (m, 1H, CH3), 6.84 (m, 1H, CH4), 6.97(m, 1H,
CH5), 4.57(d, 2JHH = 24.81 Hz, 1H, CH27), 4.78 (d,
2JHH = 25.24 Hz, 1H, CH27’), 7.18 (m, 3H,CH11–CH13), 1.43 (d,
3.5. Synthesis of 3
A cold solution (ꢀ5 °C) of (2,6-diisopropylphenyl)diazabutadi-
ene (1.50 g, 4 mmol) in 100 ml of diethyl ether was slowly, during
30 min, added by drops to a vigorously stirred solution of Ni(allyl)2
(0.564 g, 4 mmol) in 100 ml of diethyl ether keeping the tempera-
ture at ꢀ5 °C. The resulting bright red reaction mixture was kept at
this temperature for another 2 h followed by filtration. The filtrate
was evaporated to give a bright red powder. This was dissolved in
50 ml of pentane at ꢀ5 °C. The solution was kept in a refrigerator at
ꢀ30 °C for five days to obtain a crystalline precipitate as thin bright
red plates. The crystals were filtered off at ꢀ30 °C and dried in vac-
uum for 6 h at 10ꢀ2 mbar, 20 °C). The product is stable in argon but
air-sensitive.
Yield 1.07 g (2.08 mmol), 52%.
Decomp. 60 – 65 °C. Anal. Calc. for C32H46N2Ni (517.41): C,
74.28; H, 8.96; N, 5.41; Ni, 11.34. Found: C, 75.16; H, 8.20; N, 4.92%.
HRMS: C32H46N2Ni calculated
– 516.3014, measured –
516.29939 (ꢀ2 mmu).
MS (70 eV): m/z (%) = 41(24.9), 59(13.9), 186(13.0), 228(43.2),
418(33.4), 434(42.9), 476(100.0), 516(74.8).
2
2JHH = 13.8 Hz, 1H, CH215), 1.59 (d, JHH = 6.25 Hz, 1H,
2
CH215’), 5.35(m, 1H, CH16), 1.41 (d, JHH = 8.89 Hz, 1H,
IR (KBr) cmꢀ1: 3052(m), 3012(s), 2960(s), 2923(s), 2865(s),
2740(m), 2688(s), 1932(s), 1913(s), 1872(s), 1847(s), 1812(s),
1783(s), 1762(s), 1602(N@C,s) 1571(s), 1461(d), 1363(s), 1355(s),
1313(vs), 1253(s), 1105(s), 1076(vs), 987(vs), 919(s), 892(s),
794(s), 754(d), 568(s), 532(s).
2
CH217), 1.60 (d, JHH = 12.88 Hz, 1H, CH217’), 4.51 (m, 1H,
CH18), 1.26 (m, 3H, CH319), 1.29 (m, 3H, CH320), 3.88 (m,
1H, CH21), 1.20 (m, 6H, CH322, CH323), 5.70 (d, 3JHH = 15.7 Hz,
3
2H, CH24), 6.52 (m, 1H, CH25), 1.64 (d, JHH = 6.98 Hz, 3H,
CH326), 3.37 (m, 1H, CH27), 1.35 (m, 3H, CH328), 1.37(m,
3H, CH329), 3.66 (m, 1H, CH30), 1.11 (m, 3H, CH331),
1H NMR (500 MHz, [D8]THF, 297 K): d = 6.95 (d, JHH = 7.12 Hz,
3
3
1H, CH3), 6.86 (m, 1H, CH4), 6.98(d, JHH = 6.87 Hz 1H, CH5),
1.16(m, 3H, CH332) ppm (Fig. 4).13
C NMR (125 MHz,
2
2
4.37(d, JHH = 26.34 Hz, 1H, CH27), 4.55 (d, JHH = 26.34 Hz, 1H,
[D8]THF, 297 K): d = 158.17(C1), 148.02(C2), 123.43(C3),
123.02(C4), 123.53(C5), 146.54(C6), 69.56(C7), 184.13(C8),
2
CH27’), 7.20 (m, 3H,CH11–CH13), 1.44 (d, JHH = 4.96 Hz, 1H,
2
CH215), 1.59 (d, JHH = 12.90 Hz, 1H, CH215’), 5.34(m, 1H, CH16),
147.17(C9),
124.43(C13),
139.71(C10),
140.20(C14),
124.17(C11),
50.72(C15),
127.13(C12),
106.71(C16),
2
2
1.43 (d, JHH = 7.96 Hz, 1H, CH217), 1.62 (d, JHH = 12.94 Hz, 1H,
CH217’), 4.50 (m, 1H, CH18), 1.38 (m, 3H, CH319), 1.40 (m, 3H,
CH320), 3.86 (m, 1H, CH21), 1.31 (m, 6H, CH322, CH323), 2.88 (m,
2H, CH24), 5.73 (m, 1H, CH25), 5.01 (m, 2H, CH26), 3.32 (m, 1H,
CH27), 1.29 (m, 6H, CH328, CH329), 3.61 (m, 1H, CH30), 1.22 (m,
6H, CH331, CH332) ppm (Fig. 3).
53.97(C17), 28.45(C18), 26.10(C19), 26.26(C20), 28.28(C21),
24.89(C22), 25.15(C23), 124.10(C24), 140.89(C25),
19.27(C26), 29.22(C27), 23.78(C28), 24.00(C29), 29.42(C30),
24.28(C31), 24.62(C32) ppm (Fig. 4).1H NMR (500 MHz,
C6D6, 297 K): d = 7.27 (m, 1H, CH3), 7.23 (m, 1H, CH4),
7.32(m, 1H, CH5), 4.68(d, 2JHH = 25.30 Hz, 1H, CH27), 4.90 (d,
2JHH = 25.30 Hz, 1H, CH27’), 7.06 (m, 3H,CH11–CH13), 1.79
13C NMR (125 MHz, [D8]THF, 297 K): d = 157.84(C1),
147.87(C2), 123.43(C3), 123.06(C4), 123.54(C5), 146.33(C6),
72.82(C7), 191.36(C8), 146.67(C9), 139.26(C10), 124.41(C11),
127.33(C12), 124.67(C13), 139.61(C14), 50.62(C15), 106.39(C16),
2
2
(d, JHH = 12.98 Hz, 1H, CH215), 2.00 (d, JHH = 4.27 Hz, 1H,
26
26
23
6
29
23
6
29
25
25
28
28
27
9
22
7
27
9
21
22
7
21
24
8
24
10
5
11
13
8
10
5
11
13
12
N
N
4
N
N
12
1
1
Ni
Ni
17
15
17
15
3
14
3
14
2
2
16
16
30
30
18
18
19
19
32
32
31
31
20
20
Fig. 3. Numbering scheme of carbon atoms in 3.
Fig. 4. Numbering scheme of carbon atoms in 4.

P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 694 (2009) 3912–3917
3917
2
[3] W. Keim, A. Behr, B. Gruber, B. Hoffmann, F. Kowaldt, U. Kurschner, B.
Limbacker, F. Sistig, Organometallics 5 (1986) 2356–2359.
[4] W. Keim, Angew. Chem. 102 (1990) 251–260. Angew. Chem., Int. Ed. Engl. 29
(1990) 235–244.
[5] L.K. Johnson, C.M. Killian, M. Brookhart, J. Am. Chem. Soc. 117 (1995) 6414–
6415.
CH215’), 5.46(m, 1H, CH16), 1.62 (d, JHH = 5.36 Hz, 1H,
2
CH217), 1.83 (d, JHH = 12.98 Hz, 1H, CH217’), 4.81 (m, 1H,
CH18), 1.47 (m, 3H, CH319), 1.53 (m, 3H, CH320), 4.14 (m,
1H, CH21), 1.41 (m, 6H, CH322, CH323), 5.65 (d, 3JHH = 15.8 Hz,
2H, CH24), 5.88 (dk, 3JHH = 6.97 Hz, 3JHH = 16.2 Hz 1H, CH25),
[6] C.M. Killian, D.J. Tempel, L.K. Johnson, M. Brookhart, J. Am. Chem. Soc. 118
(1996) 11664–11665.
3
0.94 (d, JHH = 6.53 Hz, 3H, CH326), 3.46 (m, 1H, CH27), 1.28
[7] C.M. Killian, L.K. Johnson, M. Brookhart, Organometallics 16 (1997) 2005–2007.
[8] P. Preishuber-Pflugl, M. Brookhart, Macromolecules 35 (2002) 6074–6076.
[9] S.A. Svejda, M. Brookhart, Organometallics 18 (1999) 65–74.
[10] S.A. Svejda, L.K. Johnson, M. Brookhart, J. Am. Chem. Soc. 121 (1999)
10634–10635.
[11] D.P. Gates, S.A. Svejda, E. Onate, C.M. Killian, L.K. Johnson, P.S. White, M.
Brookhart, Macromolecules 33 (2000) 2320–2334.
[12] (a) M.D. Leatherman, S.A. Svejda, L.K. Johnson, M. Brookhart, J. Am. Chem. Soc.
125 (2003) 3068–3081;
(m, 3H, CH328), 1.37(m, 3H, CH329), 3.75 (m, 1H, CH30),
1.10 (m, 3H, CH331), 1.15(m, 3H, CH332) ppm (Fig. 4).13
C
NMR (125 MHz, C6D6, 297 K): d = 157.99(C1), 147.96(C2),
123.55(C3), 123.79(C4), 123.58(C5), 146.37(C6), 69.69(C7),
183.46(C8),
126.95(C12),
106.76(C16),
26.42(C20),
123.77(C24),
146.80(C9),
124.18(C13),
54.09(C17),
28.20(C21),
139.82(C25),
139.41(C10),
139.85(C14),
28.36(C18),
25.01(C22),
18.81(C26),
123.87(C11),
51.09(C15),
26.23(C19),
25.35(C23),
28.81(C27),
(b) A.R. O’Connor, P.S. White, M. Brookhard, J. Am. Chem. Soc. 129 (2007)
4142–4143;
(c) A.R. O’Connor, S.A. Urbin, R.A. Moorhouse, P.S. White, M. Brookhard,
Organometallics 28 (2009) 2372–2384.
23.70(C28), 23.89(C29), 29.00(C30), 24.29(C31), 24.62(C32)
ppm (Fig. 4).
[13] L. Jafarpour, E.D. Stevens, S.P. Nolan, J. Organomet. Chem. 606 (2000) 49–54.
[14] E. Kogut, A. Zeller, T.H. Warren, T. Strassner, J. Am. Chem. Soc. 126 (2004)
11984–11994.
[15] K.M. Smith, Organometallics 24 (2005) 778–784.
[16] G. Bai, P. Wei, D.W. Stephan, Organometallics 24 (2005) 5901–5908.
[17] R.D.J. Froese, P.D. Hustad, R.L. Kuhlman, T.T. Wenzel, J. Am. Chem. Soc. 129
(2007) 7831–7840.
[18] K.E. Kristian, M. Iimura, S.A. Cummings, J.R. Norton, K.E. Janak, K. Pang,
Organometallics 28 (2009) 493–498.
[19] L.R. Sita, J.R. Babcock, Organometallics 17 (1998) 5228–5230.
[20] D. Neculai, H.W. Roesky, A. Neculai, J. Magull, R. Herbst-Irmer, B. Walfort, D.
Stalke, Organometallics 22 (2003) 2279–2283.
(b) A solution of complex 3 in THF-D8 sealed in an NMR-tube
was monitored with NMR-DEPR 13C method using the sig-
nals of the C26 atom (Fig. 4) as distinctive ones. After 3 h
at 25 °C the signal at 119.48 ppm (complex 3) was com-
pletely replaced by the signal at 19.27 ppm (complex 4).
The transformation of complex 3 into complex 4 is almost
100%.
[21] Y. Champouret, J. Fawcett, W.J. Nodes, K. Singh, G.A. Solan, Inorg. Chem. 45
(2006) 9890–9900.
[22] S. Gu, W. Chen, Organometallics 28 (2009) 909–914.
[23] H. Tsurugi, Y. Matsuo, T. Yamagata, K. Mashima, Organometallics 23 (2004)
2797–2805.
[24] R. Zavoianu, C. Nenu, E. Angelescu, Catal. Commun. 6 (2005) 415–420.
[25] D. Meinhard, P. Reuter, B. Rieger, Organometallics 26 (2007) 751–754.
[26] X. Tang, W.-H. Sun, T. Gao, J. Hou, J. Chen, W. Chen, J. Organomet. Chem. 690
(2005) 1570–1580.
[27] J. Flapper, H. Kooijman, M. Lutz, A.L. Spek, P.W.N.M. van Leeuwen, C.J. Elsevier,
P. Kamer, Organometallics 28 (2009) 1180–1192.
[28] P. Chavez, I.G. Rios, A. Kermagoret, R. Pattacini, A. Meli, C. Bianchini, G.
Giambastiani, P. Braunstein, Organometallics 28 (2009) 1776–1784.
[29] S.O. Ojwach, I.A. Guzei, L.L. Benade, S.F. Mapolie, J. Darkwa, Organometallics 28
(2009) 2127–2133.
[30] T.K. Goswami, M. Roy, M. Nethaji, A.R. Chakravarty, Organometallics 28 (2009)
1992–1994.
Acknowledgements
We are grateful to Prof. J.J. Schneider for providing laboratory
facilities. P.K. thanks DAAD Michail-Lomonosov-Forschungsstipen-
dien (No. 8168) for a research stipendium. P. K. is indebted to Kris-
tina Vinober for helpful joint discussion and interpretation of the
results.
This work was supported by the RFBR (Russia) and CRDF (USA)
(The international Grant No. RUC1-2862-IR-07).
Appendix A. Supplementary material
[31] S.-W. Lai, Q.K.-W. Chan, J. Han, Y.-G. Zhi, N. Zhu, C.-M. Che, Organometallics 28
(2009) 34–37.
CCDC 730019 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/j.jorganchem.
2009.08.010.
[32] D. Wang, S. Li, X. Liu, W. Gao, D. Cui, Organometallics 27 (2008) 6531–6538.
[33] H. Bönnemann, B. Bogdanovic, G. Wilke, Angew. Chem. 79 (1967) 817–818.
[34] (a) B. Henc, P.W. Jolly, R. Salz, G. Wilke, R. Benn, E.G. Hoffmann, R. Mynott, G.
Schroth, K. Seevogel, J.C. Sekutowski, C. Krüger, J. Organomet. Chem. 191
(1980) 425–448;
(b) R.E. Wilde, T.K.K. Srinivasan, S.N. Ghosh, J. Inorg. Nucl. Chem. 35 (1973)
1017–1021.
[35] P. De Waele, B.A. Jazdzewski, J. Klosin, R.E. Murray, C.N. Theriault, P.C.
Vosejpka, J.L. Petersen, Organometallics 26 (2007) 3896–3899.
[36] P.J. Bailey, C.M. Dick, S. Fabre, S. Parson, L.J. Yellowlees, Dalton Trans. 13 (2006)
1602–1610.
References
[1] W. Keim, B. Hoffmann, R. Lodewick, M. Peuckert, G. Schmitt, J. Fleischhauer, U.
Meier, J. Mol. Catal. 6 (1979) 79–97.
[2] M. Peuckert, W. Keim, Organometallics 2 (1983) 594–597.