Intramolecular rearrangement of the imine-amide ligand within the nickel coordination sphere affected by carbon monoxide

Article abstract of DOI:10.1016/j.jorganchem.2011.07.022

The interactions of the nickel imine-amide allyl complex 1 with carbon monoxide and unsaturated hydrocarbons have been studied. It is shown that this complex reacts readily with carbon monoxide to form the nickel(0) diimine carbonyl complex [(2-(1-propenyl)-[1,10]phenanthroline)Ni(CO)₂] 2. During the process the ligand undergoes a deep transformation within the nickel coordination sphere. Specifically, the nickel-nitrogen σ-bond turns to an N-donor bond with aromatization of a ring in the nitrogen-containing ligand. This novel heteroaromatic ligand 2-(1-propenyl)-[1,10]phenanthroline has been isolated; the nickel(0) diimine carbonyl complex 2 has been studied with X-ray diffraction method. The comparative spectral studies of complexes 1, 2, and 2-(1-propenyl)-[1,10]phenanthroline have been carried out with UV/vis, IR-FT, and 2D NMR spectroscopy. It has been shown that the planar 16-electron nickel(II) imine-amide allyl complex 1 is indifferent to olefins and acetylenes. Based on the NMR data, this fact can be explained by the inability of the π-δ rearrangement into 1.

Full text of DOI:10.1016/j.jorganchem.2011.07.022

Journal of Organometallic Chemistry 696 (2011) 3376e3383
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Intramolecular rearrangement of the imineeamide ligand within the nickel
coordination sphere affected by carbon monoxide
,
b
,
a
b
c
b
Peter B. Kraikivskii a , Hans-Friedrich Klein , Vitaly V. Saraev , Nils E. Schlörer , Victoria V. Bocharova
*
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. Marks 1, 664003 Irkutsk, Russia
c Department für Chemie, Universität zu Köln, Greinstrasse 4, 50939 Köln, Germany
a r t i c l e i n f o
a b s t r a c t
D2-
3
Article history:
The interactions of the nickel imineeamide allyl complex
1 with carbon
C N N C Ni(η -allyl)
Received 7 June 2011
Received in revised form
13 July 2011
monoxide and unsaturated hydrocarbons have been studied. It is shown that this complex reacts readily
with carbon monoxide to form the nickel(0) diimine carbonyl complex [(2-(1-propenyl)-[1,10]phenan-
throline)Ni(CO)2] 2. During the process the ligand undergoes a deep transformation within the nickel
Accepted 18 July 2011
coordination sphere. Specifically, the nickelenitrogen s-bond turns to an N-donor bond with aromati-
zation of a ring in the nitrogen-containing ligand. This novel heteroaromatic ligand 2-(1-propenyl)-[1,10]
phenanthroline has been isolated; the nickel(0) diimine carbonyl complex 2 has been studied with X-ray
diffraction method. The comparative spectral studies of complexes 1, 2, and 2-(1-propenyl)-[1,10]phe-
nanthroline have been carried out with UV/vis, IR-FT, and 2D NMR spectroscopy. It has been shown that
the planar 16-electron nickel(II) imineeamide allyl complex 1 is indifferent to olefins and acetylenes.
Keywords:
Nickel
Diimine ligands
Chelates
Structure elucidation
Based on the NMR data, this fact can be explained by the inability of the
p-d rearrangement into 1.
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
stated that ligands are usually regarded as an unchanging unit
which can be “hosted” in the metal coordination sphere or driven
out of it in the course of catalytic cycle. It is generally accepted that
the state of a transition metal can alter radically at different steps of
the catalytic cycle, whereas the possibility of any transformations of
ligands is neglected as a rule [3,13e19]. Nevertheless, every aspect
of the ligand behavior should be understood and intelligently used,
because it may be the only way to atom-economic catalytic systems
most consistent with the principles of green chemistry.
Polymerization of olefins is still one of the most important
industrial processes today and
products. In 1995 the work of Brookhart et al. [1] on the usage of
nickel and palladium ediimine complexes for polymerization
a-olefins are the most valuable
a
attracted attention of the scientific community at large. It served as
a powerful stimulus for studying diimine complexes of transition
metals in polymerization of both linear and cyclic olefins [2e7].
Transition metal allyl complexes with nitrogen-containing ligands
are the most interesting subjects for investigations as they bear an
active metalecarbon bond inside their coordination sphere that
makes such systems promising for organic fine chemicals synthesis
and metal complex catalysis [8e12].
The least known today is the possibility of transformations of N-
containing ligands themselves within transition metal coordination
sphere. For this reason almost all catalytic cycle schemes proposed
in the literature, including activation and deactivation of the active
species, ignore the possibility that the nature of metaleligand
bonds and, furthermore, the diimine ligand itself can alter. It can be
The possibility of a profound transformation of diimine ligands
within the coordination sphere of
was demonstrated in [20]. The process involves formation of
a nickelenitrogen -bond and an imineeamide complex. Interest-
a nickel p-allyl complex
s
ingly, phenanthroline, usually a stable ligand, looses aromaticity in
one of its heteroatomic rings under very mild conditions (Scheme 1):
Our work focuses on the chemical properties of complex 1,
specifically, whether there is a possibility for this spontaneously
formed imineeamide complex to undergo further transformations
inside the nickel coordination sphere when affected by the
conventional catalytic ligands such as olefins, acetylenes, and
carbon monoxide. We hope that our research will help in following
the ways of how nitrogen-containing ligands transform that could
complement the catalytic cycle puzzle and facilitate the develop-
ment of catalytic systems with desired properties.
* Corresponding author. Department of Chemistry, Irkutsk State University, Str. K.
Marks 1, 664003 Irkutsk, Russia.
E-mail address: peter10@list.ru (P.B. Kraikivskii).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.07.022

P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 696 (2011) 3376e3383
3377
+
Ni
N
N
N
N
Ni
1
Scheme 1.
2. Results and discussion
(the structure is shown on Fig. 1; the crystal packing is given in
Supplementary material).
Nickel di- and monoallyl complexes are classic catalysts for
conversions of olefins, dienes and acetylenes [8]. According to an X-
ray structural analysis and multinuclear 2D NMR spectroscopy [20]
According to NMR data, dissolution of the adduct in THF or
toluene does not bring about an interaction between 2 and pphen.
The 1H NMR spectrum shows a simple superposition of signals from
2 and pphen (Fig. 2). The solution contained 2 and pphen in
approximately equimolar amounts as follows from the corre-
sponding integral intensities of the 1H NMR signals. Analysis of the
TOCSY and NOESY spectrum reveals no mutual cross-peaks for 2
and pphen.
Analysis of the summation of the obtained data suggests that 1
and CO react in the following way (Scheme 2):
Among the products pphen and tetracarbonylnickel should be
taken out. Their presence is explained by Scheme 3.
According to Scheme 2, the reaction of complex 1 and carbon
monoxide involves reduction of nickel(II) to nickel(0) and forma-
tion of the dicarbonyl complex together with the profound trans-
formation of the ligand, specifically, the ring aromatization and
migration of the double bond within the propenyl substituent.
Attempts to separate 2 and pphen using crystallization from
different solutions failed. The crystalline adduct, prepared accord-
ing to Scheme 2, was divided into complex 2 and pphen only
chromatographically. The isolated individual complex 2 was sub-
jected to crystallization from different solvents (pentane, diethyl
ether, toluene, THF, and mixtures). Unfortunately, complex 2 always
precipitated as an X-ray amorphous bright red powder.
When 1 reacted with CO under isobaric conditions in a non-flow
reactor (P ¼ 1 kg/cm2, 20 ꢀC), the initial bright green color of the
solution quickly turned bright red. The absorption of the gas ceased
when the molar ratio of CO:Ni reached 3. From the obtained solu-
tion a powdery bright red X-ray amorphous product was prepared
with the yield of 90e92%. Its spectra were identical to those of
complex 2. Using GCeMS it was also established that the reaction of
1 has a planar structure, contains a
p-allyl group, an active frag-
ment, and, besides, it is electron-deficient with its 16-electron
pattern. On the whole complex 1 meets all the conventional
requirements for a catalyst [21]. This complex is to be active in
catalytic conversions of unsaturated hydrocarbons or at least in
some interactions with them. We tried to initiate reactions
between 1 and ethylene, propylene, norbornadiene, styrene, acet-
ylene, and phenylacetylene. The molar ratios between 1 and the
unsaturated hydrocarbons varied from 1:1 to 1:100, while the
reaction temperature varied from 20 to 70 ꢀC. Under these condi-
tions the NMR spectra of complex 1 remained unchanged. We could
observe only a superposition of chemical shifts from 1 and the used
unsaturated hydrocarbon. Of special interest is the fact of a total
indifference of 1 toward acetylene and phenylacetylene, as it was
quite logical to assume loss of the allyl group by acetylenes due to
the acetylene acidic proton. This irritating inertness provoked
further tests of 1 with carbon monoxide.
When carbon monoxide was admitted to a bright green ether
solution of 1 in a flow reactor, the color quickly changed to bright
red followed by a partial fading during 10e14 h. Using GCeMS it
was established that the moment of the initial color change was
accompanied by formation of acrylic aldehyde in the amount
equimolar to the nickel. Further the content of acrylic aldehyde
stayed constant in the course of the process.
When the change in the coloration ceased, the crystalline (1:1)-
adduct consisting of complex 2 and 2-(1-propenyl)-[1,10]phenan-
throline (pphen) was obtained from the solution. We studied the
molecular structure of the adduct with X-ray structural analysis
Fig. 1. Molecular structure of adduct of 2 and pphen. (ORTEP plot with hydrogen atoms omitted); distances between selected atoms [Å] and angles [ꢀ]: NieN1 ¼ 2.015(2),
NieN2 ¼ 2.052(2), NieC16 ¼ 1.747(3), NieC17 ¼ 1.760(3), C16eO1 ¼ 1.160(4), C17eO2 ¼ 1.151(4), N1eNieN2 ¼ 81.47(10), N1eNieC16 ¼ 114.42 (12), N2eNieC17 ¼ 118.11(12),
N2eNieC16 ¼ 113.12(12), N1eNieC17 ¼ 112.10(12), C16eNieC17 ¼ 113.76(14).

3378
P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 696 (2011) 3376e3383
Fig. 2. Informative region of the 1H NMR spectrum for complex 2 (1), solution of crystalline adduct of 2 with pphen (2), and free pphen (3), 500 MHz, THF-D8, 297 K.
1 and CO gives rise to acrylic aldehyde in the amount equimolar to
the nickel. The detailed analysis of 1H NMR spectra of the reaction
solution revealed that in the isobaric system under the used
conditions complex 2 forms together with free pphen, but, unlike
the flow system, in a small amount. The molar ratio of 2:pphen is
1:0.03 according to the integration of quantitative 1H NMR spectra.
The presence of free pphen can be explained only by the
reversible reaction between 2 and CO (Scheme 3):
complex 1
d
15N1 ¼ ꢂ145. For N2 the 1He15N-HMBC spectrum
contained no cross-peaks that is obviously associated with broad-
ening of the line due to the NieN
d-bond. For free pphen
d
15N1 ¼ ꢂ65 and
d
15N2 ¼ ꢂ76ppm. Thus, the analysis of all the
1He15N-HMBC data suggests that the nitrogen nuclear in allyl
complex 1 is most shielded. It seems to be caused by the essential
displacement of electron density to the nitrogen from the metal
and allyl group.
The equilibrium constant Keq is 9ꢁ10ꢂ4 for the experiment
conditions (P ¼ 1 kg/cm2, 20 ꢀC); the concentration of CO is
assumed to be stationary for the isobaric process. For the reaction
in a flow reactor at 20 ꢀC, provided blowing-out of the volatile
Ni(CO)4, the equilibrium corresponds to the molar ratio of
2:pphen ¼ 1:1.02 (from the integration of 1H NMR spectra).
The 13C NMR spectrum of complex 2 demonstrates the signal at
197 ppm which is characteristic for carbon monoxide coordinated
to nickel [22]. The proton spectrum directs attention to a doublet of
doublets widely displaced to low field (9.6 ppm) that indicates to
a strong deshielding in the non-substituted aromatic ring of the
ligand. For free pphen the signal of the analogous proton is located
in a higher field at 9 ppm (Table 1).
The nature of this effect can be better appreciated from an
analysis of the proton spectrum of the allyl group in complex 1.
The 1H NMR spectrum of complex 1 contains signals which
differ significantly from the signals reported in the literature for
nickel and palladium allyl complexes [23]. First, in contrast with
Ni(allyl)2 [23], there is an essential displacement of the signals of
the central and anti-protons to low field (Table 1) that is indicative
of a substantial deshielding of the protons. At the same time the
signals of syn-protons are widely displaced to high field in
comparison with those of Ni(allyl)2. There is
a significant
nonequivalence of both the syn- and anti-protons of the allyl group.
Forcomplex1 the spinespincouplingconstantforthesyn-protons
H16s and H18s is 2.1 Hz. This nonequivalence seems to be associated
with a strong interaction of the allyl group and imineeamide ligand.
The presence of the selective cross-peaks for the protons H16seH1
and H18seH10 in the NOESY spectrum (Fig. 3) validates this
assumption.
According to the X-ray structural analysis, the NieN bond
lengths in complex 2 are significantly longer than those for
complex 1 (NieN1 ¼ 2.015 Å and 1.921 Å, NieN2 2.052 Å and
1.896 Å for 2 and 1 [20], respectively). It is quite consistent with the
transformation of the NieN
d
-bond of 1 to the coordination bond of
Thus, the interaction with so different in their nature moieties of
the imineeamide ligand results in an essential anisotropy in the
allyl fragment of the complex. A similar pattern was reported for
2. The 1He15N-HMBC spectra of complex 2 have
d
15N1 and 15N2
d
at ꢂ112 and ꢂ117 ppm, respectively, whereas in the case of
O
+ 3 CO
+
pphen
+ Ni(CO)4
+
H
N
N
N
N
Ni
Ni
2
CO
OC
Scheme 2.

P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 696 (2011) 3376e3383
3379
+ CO
-CO
+
Ni(CO)4
N
N
N
N
Ni
CO
CO
Scheme 3.
the palladium allyl complexes with bulky branched nitrogen-
containing ligands [10]. In solution complex 1 exists as an almost
equimolar mixture of its cis- and trans-isomers [20]. The NMR
spectra of the cis- and trans-isomers have no essential differences
other than a displacement of the signals that allows clear identifi-
cation of the isomers. From our viewpoint all the considerations on
the spectral data are valid for the both isomers.
transition region that is characteristic for the d10-nickel. In [28]
a similar effect was reported for the nickel bipyridyl complexes
when nickel(II) was reduced to nickel(0). Weak bands within
340e355 nm are attributable to the n/
nitrogen-containing rings [29]. Compared to the similar band of
phenanthroline (350e360 nm), the spectrum of complex
p* transitions of the
2
demonstrates an insignificant blue displacement together with
The presence of the NOESY selective cross-peaks for the protons
of allyl group and imineeamide ligand suggests a significant
conjugation of the whole electron system of the nickel ligand
surroundings. This is also favorable to the stability of complex 1
despite the formal 16-electron environment.
The vibration spectrum of complex 2 contains two absorption
bands at 1970 cmꢂ1 and 1875 cmꢂ1 characteristic for the carbonyl
stretching frequencies nCO [24]. Similar bands of the carbonyl
stretching frequencies are present in the IR spectrum of the nickel
splitting. The blue displacement can be explained by a decrease in
the energy of the n-orbital due to the
p-p conjugation of the
nitrogen electron pair with the allyl group
p
-system that is quite
consistent with the data of the 1He15N-HMBC spectra. The splitting
of the band can be connected with a nonequivalence of the electron
environment of the nitrogen atoms, in particular, with the influence
of the propenyl substituent.
The summation of the spectral data allows us to conclude that
the imineeamide ligand in complex 1 has the resulting character of
a distinct electron-acceptor. It is well known that the introduction
of acceptor ligands in allyl complexes dramatically enhances their
stability [8]. Thus, when the imine character of the metalenitrogen
bond transforms to the amide type, the stability of allyl structures
in organometallic complexes goes up dramatically that may be
responsible for deactivation of catalysts, if this rearrangement takes
dicarbolyl phenanthroline complex Ni(phen)(CO)2
1915 cmꢂ1) [25]. The lower values of the carbonyl stretching
frequencies for complex in comparison with those for
Ni(phen)(CO)2 are indicative of a more limited transition d(Ni)/
*(CO) and, correspondingly, a more limited total resulting electron
(nCO ¼ 1980,
2
p
donor function of pphen as compared to phenanthroline.
The UV/vis spectra of complex 1 (Fig. 4) have bands at 219,
233 nm, and a split one within 268e277 nm which belong to the
place during the catalytic cycle. When a further p-acceptor ligand,
e.g. carbon monoxide, is introduced at the nickel center, the allyl-
nickel group is activated that can lead to the transformation of the
imineeamide ligand to the diimine type.
p/p* transitions in the ligand nitrogen-containing rings. The
splitting in the 268e277 nm region seems to be brought about by
the nonequivalence of the nitrogen-containing rings one of which
is not aromatic but involved in the collective
p-conjugation
3. Conclusions
through the double bond. For comparison it should be mentioned
that in the considered spectral region phenanthroline has two non-
split bands at 221 and 272 nm [26].
The obtained results are rationalized in the form of a scheme
representing all the studied transformations (Scheme 4):
Two weak bands at 424 and 454 nm are characteristic for the d-
The first step of the interaction between the allyl complex and
phenanthroline is most likely to be the formation of intermediate
transitions in plane d8-nickel complexes [27].
For complex 2 the UV/vis spectra demonstrate p/p* bands in
labile bis-pes allyl complex a. Its coordination sphere undergoes
almost the same locations (219, 233 and 279 nm), however, it
should be mentioned that the long-wave band is not split. It is
obviously related to the restoration of the aromaticity of the N-
containing ring. Also notice that there are no bands in the d-
a rearrangement which can be regarded as the insertion of the C]N
fragment, activated by the coordination to the nickel, into the
metalecarbon bond. This reaction results in formation of stable
imineeamide complex 1 containing allyl group firmly stabilized in
Table 1
Chemical shifts d
(ppm) for selected atomsa of the discussed compounds.
Compound
dH16anti
dH18anti
dH17
dH16syn
dH18syn
dH1
dH10
dN1
dN2
1
cis:
2.57
cis:
2.14
cis:
cis:
3.08
J16se17 ¼ 7.0
J16se18s ¼ 2.1
trans:
cis:
2.78
J18se17 ¼ 7.4
J18se16s ¼ 2.1
trans:
cis:
cis:
ꢂ145
e
5.67
trans:
5.87
8.30
trans:
8.30
4.32
trans:
8.42
J16ae17 ¼ 13.1
J18ae17 ¼ 12.7
trans:
trans:
2.51
2.24
J16ae17 ¼ 13.0
J18ae17 ¼ 12.9
3.1
2.89
J16se17 ¼ 7.0
J16se18s ¼ 2.2
3.76
J18se17 ¼ 6.9
J18se16s ¼ 2.0
Ni(allyl)2 [8]
1.67
4.9
J16ae17 ¼ 14.3
J16se17 ¼ 7.6
2
e
e
e
e
e
e
e
e
e
9.58
9.06
e
e
ꢂ112
ꢂ65
ꢂ117
ꢂ77
pphen
e
a
Atom numbering is in agreement with the molecular fragment at Fig. 3.

3380
P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 696 (2011) 3376e3383
the
p
-form. The coordination of carbon monoxide to 1 most likely
rearrangement resulting in activation of the
allyl group in intermediate complex b. Further the coordinated CO
inserts into the metalecarbon bond with following -proton
capillaries sealed under argon and are uncorrected. All NMR
experiments were carried out in evacuated and sealed NMR
ampoules.
brings about the
pe
s
b
The elemental analysis of the complexes was performed on an
FLACH 1112 analyzer (EA series). Nickel content in samples was
determined by atomic absorption spectrophotometry on a Carl
Zeiss Jena AAS-1 spectrometer using addition method.
UV/vis spectra were recorded with NICOLET spectrometer using
all-soldered quartz cuvettes.
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 and cooled down to 100 K, covered with a pro-
tecting oil film. Data collection was performed using an Xcalibur
diffractometer from Oxford Diffraction, equipped with the Enhance
transfer to form a stable heteroaromatic cycle. The process is
accompanied by the isomerization of the propenyl substituent
leaving the double bond in conjugation with the aromatic ring
(intermediate complexes c and d). The reductive elimination fol-
lowed by coordination of CO affords the stable diimine complex 2.
Further carbonylation of complex 2 proceeds as a conventional
ligand replacement leaving the diimine ligand unchanged.
We concede that the actual mechanism may differ from our
proposal in a few details. It is important that our findings indicate
the possibility of a profound transformation of nitrogen-containing
heterocyclic ligands within the coordination sphere of nickel allyl
complexes. For heteroaromatic nitrogen-containing rings such
a ready transition from the imine systems to amide ones and back
has not been reported in the literature. Our data extend the range of
views about the ligand behavior at different steps of the catalyst
formation and functioning. In particular, they bring us closer to the
understanding why catalysts with diimine ligands (Brookhart’s
catalysts) have higher stability if hydrogen atoms at the carbon,
directly bonded to the nitrogen, are replaced by less labile
substituents.
source option and Sapphire CCD detector in
4 and u-scan mode,
respectively. The structure was solved by direct methods using
SHELXS und refined using SHELXL-97. H atoms were added at
idealized positions.
The Ni(allyl)2 complex was prepared according to [8a].
Phenanthroline-1,10 and all the used solvents were purchased
(Merck).
Complex 1 was prepared according to [20].
IR: 1463(daCH2, s), 1124 (nsCCC, s), 511 (dCCC, s), 291(NieN, s)
cmꢂ1
.
NMR data
4. Experimental section
cis-isomer: 1H NMR (500 MHz, THF-D8, 297 K):
d
¼ 8.30 (m, 1H,
CH1), 7.14 (dd, JH2eH1 ¼ 13 Hz, 3JH2eH3 ¼ 8 Hz, 1H, CH2), 7.94 (dd,
3
4.1. General procedures and materials
3JH3eH2
¼
8.26 Hz, JH3eH1
¼
1 Hz, 1H, CH3), 6.76 (dd,
4
3JH5eH6 ¼ 7.80 Hz, JH5eH3 ¼ 3.50 Hz, 1H, CH5), 6.25 (dd,
4
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.
NMR spectra were obtained from on a Bruker AVANCE 500 and
an AVANCE II 600 spectrometer. Assignment of 1H, 13C and 15N
signals was supported by APT, DEPT-135, COSY, NOESY, TOCSY,
HMQC, HSQC and HMBC spectra. Melting points were measured in
3JH6eH5
¼
8
Hz, JH6eH8
¼
3.20 Hz, 1H, CH6), 6.26 (d,
4
3JH8eH9 ¼ 9.60 Hz, 1H, CH8), 5.28 (dd, JH9eH8 ¼ 9.57 Hz,
3
3JH9eH10 ¼ 4.90 Hz, 1H, CH9), 4.32 (dt, JH10eH9 ¼ 8.10 Hz,
3
3JH10eH13 ¼ 4 Hz, 1H, CH10), 2.58 (m, 1H, CH213), 2.34 (m, 1H,
3
CH2130), 5.98 (m, 1H, CH14), 5.03 (dm, JH15transeH14 ¼ 17.2 Hz,
2JH15transeH15cis
¼
2.2
Hz, 1H,
CH215trans),
4.97(dm,
3JH15ciseH14 ¼ 13.4 Hz, JH15ciseH15trans ¼ 2.2 Hz, 1H, CH215cis), 3.08
(dd, 3JH16syneH17 ¼ 7.0 Hz, 4JH16syneH18syn ¼ 2.10 Hz, 1H, CH216syn),
2.57 (d, 3JH16antieH17 ¼ 13.10 Hz, 1H, CH216anti), 5.67 (m, 1H, CH17),
2
3
4
2.78 (dd, JH18syneH17 ¼ 7.40 Hz, JH18syneH16syn ¼ 2.04 Hz, 1H,
3
CH218syn), 2.14 (d, JH18antieH17 ¼ 12.70 Hz, 1H, CH218anti) ppm
(Fig. 5).
13C NMR (125 MHz, THF-D8, 297 K):
d
¼
148.93 (d,
1JCH ¼ 180.6 Hz, C1), 121.51 (d, JCH ¼ 157.74 Hz, C2), 138.22 (d,
1
1JCH ¼ 161.26Hz, C3), 130.93 (s, C4), 128.31 (d, 1JCH ¼ 157.75 Hz, C5),
1
105.22 (d, JCH ¼ 168.22 Hz, C6), 116.67 (s, C7), 125.65 (d,
1JCH ¼ 157.74 Hz, C8), 123.57 (d, 1JCH ¼ 158.9 Hz, C9), 63.06 (C10),
155.77 (s, C11), 143.58 (s, C12), 49.56 (C13), 136.17 (C14), 116.04 (t,
1JCH ¼ 154.26 Hz, C15), 55.28 (C16), 109.95 (d, 1JCH ¼ 159.9 Hz, C17),
48.42 (C18) ppm (Fig. 4).
Fig. 3. NOESY spectrum of 1 (cis-and trans-isomers, details in Experimental section
and Supplementary material). Expansion of the region of the allyl group protons of
the complexes, 500 MHz, THF-D8, 297 K.
Fig. 4. Absorption UV/vis spectra of 1 (dotted line) and of 2 (solid line).

P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 696 (2011) 3376e3383
3381
CO
phen
+
Ni(allyl)2
N
N
N
N
N
N
N
N
Ni
Ni
b
H
H
CO
Ni
a
Ni
1
H
O
c
CO
+CO
-CO
Keq= 9x10-4
Ni(CO)4
+
N
N
N
N
N
N
Ni
2
O
H
Ni
CO
H
CO
O
d
Scheme 4.
1He15N-HMBC (1H-500 MHz, 15N-50.7 MHz THF-D8, 297 K):
¼ ꢂ145 (N1), 8.3 (CH1) ppm (Fig. 5).
atmospheric pressure, 30 ml/min) until the gas absorption was
over. During the initial 15e20 min the starting bright green solu-
tion of 1 was turning bright red that was accompanied by the active
gas absorption (about 300 ml). Further CO was kept bubbled with
the rate of 10 ml/min for 14 h. After that about 80% of the solvent
were evaporated under reduced pressure and 5 ml of pentane were
added. The resulted solution was kept at ꢂ10 ꢀC in a refrigerator for
two days and nights. The precipitated crimson-colored crystals
were filtered off at ꢂ30 ꢀC followed by washing with cold pentane
(2 ꢁ 10 ml, ꢂ30 ꢀC) and vacuum drying for 6 h at 20e25 ꢀC
(P ¼ 10ꢂ2 mmHg). The obtained powdery product is stable in argon
and decomposes readily in air with formation of smoke. Yield
0.97 g, 70%.
d
trans-Isomer: 1H NMR (500 MHz, THF-D8, 297 K):
d
¼ 8.30 (m,
1H, CH1), 7.13 (dd, 3JH2eH1 ¼13 Hz, 3JH2eH3 ¼ 7.55 Hz, 1H, CH2), 7.94
3
4
(dd, JH3eH2 ¼ 8.26 Hz, JH3eH1 ¼ 1.0 Hz, 1H, CH3), 6.765 (dd,
3JH5eH6 ¼ 7.60 Hz, JH5eH3 ¼ 3.40 Hz, 1H, CH5), 6.25 (dd,
4
3JH6eH5
¼
8
Hz, JH6eH8
¼
3.30 Hz, 1H, CH6), 6.26 (d,
4
3JH8eH9 ¼ 9.60 Hz, 1H, CH8), 5.285 (dd, JH9eH8 ¼ 9.70 Hz,
3
3JH9eH10 ¼ 4.82 Hz, 1H, CH9), 4.42 (dt, JH10eH9 ¼ 7.50 Hz,
3
3JH10eH13 ¼ 4.70 Hz, 1H, CH10), 2.34 (m, 1H, CH13), 2.15 (m, 1H,
3
CH130), 5.97 (m, 1H, CH14), 4.96 (dm, JH15transeH14 ¼ 10.1 Hz,
2JH15transeH15cis
¼
2.1 Hz, 1H, CH215trans), 4.94 (dm,
8.25 Hz, 1H, CH215trans), 3.10 (dd, JH16syn
3JH15transeH14
¼
3
4
¼ 7.0 Hz, JH16syneH18syn ¼ 2.16 Hz, 1H, CH216syn), 2.51 (d,
The crystals begin to decompose with gas evolution at 80e83 ꢀC.
C32H26N4NiO2 (557.3): calc. C 68.97, H 4.70, N 10.05, Ni 10.53;
found C 67.84, H 4.48, N 9.86, Ni 10.42.
eH17
3JH16antieH17 ¼ 13.0 Hz, 1H, CH216anti), 5.87 (m, 1H, CH17), 2.89 (dd,
3JH18syneH17 ¼ 6.9 Hz, 4JH18syneH16syn ¼ 2.03 Hz, 1H, CH218syn), 2.24
(d, 3JH18antieH17 ¼ 12.90 Hz, 1H, CH218anti) ppm (Fig. 5).
13C NMR (125 MHz, THF-D8, 297 K):
d
¼
149.04 (d,
4.3. Synthesis of 2
1JCH ¼ 190.42 Hz, C1), 121.55 (d, JCH ¼ 172.04 Hz, C2), 138.25 (d,
1
1JCH ¼ 150.2Hz, C3), 131.06 (s, C4), 128.27 (d, 1JCH ¼ 148.58 Hz, C5),
a) Crystalline adduct of 2 and pphen (0.90 g) was dissolved in
5 ml of diethyl ether-hexane (1:1 v/v). The prepared solution was
subjected to the separation with preparative column chroma-
tography (aluminum oxide, height 4 cm, d 25 mm). Red complex
2 was retained in the upper layer of the sorbent and washed
with eluent (ether-hexane) to remove pphen. Then the red layer
was quantitatively carried to a Schlenk flask and extracted with
ether (5 ꢁ 20 ml) with vigorous shaking. The extracts were
combined and about 80% of the initial volume of the solution
were evaporated under reduced pressure followed by the addi-
tion of 5 ml of pentane and cooling to ꢂ30 ꢀC. After 2e3 days
a bright red powder precipitated. It was filtered off at ꢂ30 ꢀC and
dried in vacuum (P ¼ 10ꢂ2 mmHg) at 20e25 ꢀC for 3 h. Yield
0.16 g, 30%.
b) A solution of complex 1 (1.6 g, 5 mmol) in 80 ml of diethyl
ether was vigorously stirred in carbon monoxide atmosphere at
20 ꢀC in a non-flow reactor. The pressure of CO (1 kg/cm2) was kept
constant. During the initial 5 min the starting bright green solution
of 1 was turning bright red that was accompanied by the active gas
absorption (about 300 ml). After that the reaction was finished,
about 80% of the solvent were evaporated under reduced pressure
and 5 ml of pentane were added. The resulted solution was kept
at ꢂ30 ꢀC in a refrigerator. The precipitated crimson-colored crys-
tals were filtered off at ꢂ30 ꢀC followed by washing with cold
pentane (2 ꢁ 10 ml, ꢂ30 ꢀC) and vacuum drying for 3 h at 20e25 ꢀC
(P ¼ 10ꢂ2 mmHg). Yield 1.4 g, 85%.
1
105.04 (d, JCH ¼ 168.22 Hz, C6), 116.90 (s, C7), 125.87 (d,
1JCH ¼ 156.7 Hz, C8), 123.59 (d, JCH ¼ 159.3 Hz, C9), 62.82 (C10),
1
155.78 (s, C11), 143.84 (s, C12), 48.89 (C13), 136.04 (C14), 115.86 (t,
1JCH ¼ 153.22 Hz, C15), 54.9 (C16), 112.65 (d, 1JCH ¼ 160.16 Hz, C17),
51.32 (C18) ppm (Fig. 4).
1He15N-HMBC (1H-500 MHz, 15N-50.7 MHz THF-D8, 297 K):
d
¼ ꢂ145 (N1), 8.3 (CH1) ppm (Fig. 5).
4.2. Synthesis of crystalline adduct of 2 and pphen
In a flow reactor carbon monoxide was bubbled through
a solution of 1 (1.6 g, 5 mmol) in 80 ml of diethyl ether (20 ꢀC,
6
5
4
7
8
3
9
2
12
11
10
13
N
N
14
1
1
2
Ni
17
16
18
15
Fig. 5. Numbering scheme of atoms in 1.

3382
P.B. Kraikivskii et al. / Journal of Organometallic Chemistry 696 (2011) 3376e3383
6
6
5
5
4
4
7
7
8
8
3
3
9
9
2
2
12
11
12
11
10
10
13
N
N
14
N
1
N
2
14
1
1
1
2
13
Ni
17
15
15
16
OC
CO
Fig. 7. Numbering scheme of atoms in pphen.
Fig. 6. Numbering scheme of atoms in 2.
13C NMR (150 MHz, THF-D8, 297 K):
d
¼ 150.46 (C1), 123.44 (C2),
The obtained complex 2 is stable in argon and decomposes
readily in air with formation of smoke.
136.34 (C3),129.98 (C4), 126.45 (C5),127.17 (C6),128.30 (C7),136.71
(C8), 121.13 (C9), 156.83 (C10), 147.30 (C11), 147.73 (C12), 133.52
(C13), 132.66 (C14), 18.68 (C15) ppm (Fig. 6).
Decomp. 60e65 ꢀC. C17H14N2NiO2 (336.9): calc. C 60.59, H 4.19,
N 8.31, Ni 17.42; found C 59.80, H 4.25, N 7.96, Ni 17.36.
MS (70 eV): m/z (%) ¼ 28(43.0), 41(6.9), 59(11.8), 149(6.3),
181(100.0), 219(30.9), 279(3.2).
1He15N-HMBC (1H-500 MHz, 15N-50.7 MHz THF-D8, 297 K):
d
¼ ꢂ65 (N1), 9.06 (H1); ꢂ77 (N2), 6.84 (H13) ppm (Fig. 7).
IR (KBr) cmꢂ1: 3416(vs), 3042(m), 2963(s), nCO(sym)1969(s),
nCO(asym)1886(s), 1261(s), 1090(w), 1020(w), 800(s).
Acknowledgements
1H NMR (600 MHz, THF-D8, 297 K):
d
¼
9.58 (dd,
4
3JH1eH2 ¼ 4.90 Hz, JH1eH3 ¼ 1.36 Hz, 1H, CH1), 7.81 (dd,
This work was supported by the Federal Target Program
“Research and Training Specialists in Innovative Russia,
2009e2013”, (The contract # 14.740.11.0619 for 05.10. 2010). We
thank Vsevolod Sorokin for the development and making of
exclusive glass equipment for the experiments.
3
3JH2eH3
3JH3eH2
¼
¼
8.03 Hz, JH2eH1 ¼ 4.86Hz, 1H, CH2), 8.42 (dd,
4
8.08 Hz, JH3eH1 ¼ 1.35 Hz, 1H, CH3), 7.90 (d,
3JH5eH6 ¼ 8.85 Hz, 1H, CH5), 7.88 (d, JH6eH5 ¼ 8.85 Hz, 1H, CH6),
3
3
3
8.37 (d, JH8eH9 ¼ 8.47 Hz, 1H, CH8), 8.14 (d, JH9eH8 ¼ 8.5 Hz, 1H,
CH9), 7.98 (dk, 3JH13eH14 ¼ 16.20 Hz, 4JH13eH15 ¼ 1.60 Hz, 1H, CH13),
3
3
6.92 (dk, JH14eH13 ¼ 16.30 Hz, JH14eH15 ¼ 6.80 Hz 1H, CH14), 2.12
Appendix A. Supplementary material
3
4
(dd, JH15eH14 ¼ 6.79 Hz, JH15eH13 ¼ 1.76 Hz, 3H, CH315) ppm
(Fig. 6).
CCDC 774489 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.
13C NMR (150 MHz, THF-D8, 297 K):
d
¼
152.49 (d,
1JCH ¼ 183.56 Hz, C1), 124.80 (d, JCH ¼ 167.58Hz, C2), 134.84 (d,
1
1JCH ¼ 165.88 Hz, C3),130.66 (s, C4), 126.51 (d, 1JCH ¼ 163.48 Hz, C5),
1
127.27 (d, JCH ¼ 162.46 Hz, C6), 129.06 (s, C7), 135.30 (d,
1JCH ¼ 165.18 Hz, C8), 120.84 (d, JCH ¼ 164.84 Hz, C9), 157.38 (s,
1
Appendix. Supplementary material
C10), 145.08 (s, C11), 145.45 (s, C12), 135.10 (d, 1JC13eH13 ¼ 160.16 Hz,
C13), 134.37 (dk, 1JC14eH14 ¼ 151.93 Hz, JC14e3H15 ¼ 7.78 Hz, C14),
2
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2011.07.022. These
data include MOL files and InChIKeys of the most important
compounds described in this article.
19.30 (dk, 1JC15e3H15 ¼127.66 Hz, 2JC15eH14 ¼ 7.28 Hz, C15),196.87 (s,
C16, C17) ppm (Fig. 6).
1He15N-HMBC (1H-500 MHz, 15N-50.7 MHz THF-D8, 297 K):
d
¼ ꢂ112 (N1), 9.58 (H1); ꢂ117 (N2), 8.14 (H9) ppm (Fig. 6).
References
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