Synthesis of dialkyl, diaryl and metallacyclic complexes of Ni and Pd containing pyridine, α-diimines and other nitrogen ligands. Crystal structures of the complexes cis-NiR2 py2 (R = benzyl, mesityl)

Article abstract of DOI:10.1016/S0022-328X(03)00691-0

The alkylation of NiCl₂py₄ or PdCl₂ py₂ with organomagnesium or organolithium reagents affords dialkyl complexes cis-MR₂py₂ (R=Me, CH₂ SiMe₃, CH₂Ph, CH₂CMe₂ Ph, 2,4,6-C₆H₂Me₃). The methyl and trimethylsilyl derivatives undergo ligand exchange reactions with chelating nitrogen ligands (α-diimines or 2-imidoylpyridines), yielding the corresponding dialkyl derivatives in good to excellent yields. A catalytic amount of PMe₃ induces the transformation of the nickel complex Ni(CH₂CMe₂Ph)₂ py₂ into the metallacyclic derivative NiCH₂CMe₂-o-C₆H₄(py) ₂.The latter, and the related palladacycle Pd(CH₂CMe₂-o-C₆H₄) (cod), also undergo facile ligand exchange reactions.

Full text of DOI:10.1016/S0022-328X(03)00691-0

Journal of Organometallic Chemistry 683 (2003) 220ꢂ239
/
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Synthesis of dialkyl, diaryl and metallacyclic complexes of Ni and Pd
containing pyridine, a-diimines and other nitrogen ligands
Crystal structures of the complexes cis-NiR2py2 (Rꢀ
/
benzyl, mesityl)
Juan Ca´mpora a,*, Mar´ıa del Mar Conejo a, Kurt Mereiter b, Pilar Palma a,
Carmen Pe´rez a, Manuel L. Reyes a, Caridad Ruiz c
a Instituto de Investigaciones Qu´ımicas, Consejo Superior de Investigaciones Cient´ıficas-Universidad de Sevilla, c/Ame´rico Vespucio, s/n, 41092 Sevilla,
Spain
b Department of Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
c Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cient´ıficas, Campus de Cantoblanco, 28049 Madrid, Spain
Received 26 March 2003; received in revised form 3 July 2003; accepted 14 July 2003
Abstract
The alkylation of NiCl2py4 or PdCl2py2 with organomagnesium or organolithium reagents affords dialkyl complexes cis-MR2py2
(RꢀMe, CH2SiMe3, CH2Ph, CH2CMe2Ph, 2,4,6-C6H2Me3). The methyl and trimethylsilyl derivatives undergo ligand exchange
/
reactions with chelating nitrogen ligands (a-diimines or 2-imidoylpyridines), yielding the corresponding dialkyl derivatives in good
to excellent yields. A catalytic amount of PMe3 induces the transformation of the nickel complex Ni(CH2CMe2Ph)2py2 into the
ꢀ
ꢁ
ꢀ
ꢁ
metallacyclic derivative NiCH2CMe2-o-C6H4(py)2:/The latter, and the related palladacycle Pd(CH2CMe2-o-C6H4) (cod); also
undergo facile ligand exchange reactions.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Nickel; Palladium; Alkyl; Metallacycle; Nitrogen ligands
1. Introduction
decrease the rate of chain transfer, leading to high
molecular weight polymers. This pioneer work has
triggered a wide interest in the use of late transition
metal catalysts for olefin polymerization [3]. Although
MAO or related aluminium alkyls [2,4] may be used as
co-catalysts, alkyl derivatives of Ni(II) and Pd(II) can be
employed directly as catalyst precursors [3,5], an alter-
native that becomes specially useful in co-polymeriza-
tion reactions of ethylene and polar monomers [6].
Although the chemistry of nickel and palladium alkyl
complexes that contain phosphine ligands is well devel-
oped [7], the preparation of similar derivatives stabilized
by hard nitrogen ligands (other than bipyridyl and its
derivatives) frequently poses important difficulties.
Compared with phosphines, amine or imine ligands
usually posses a lower stabilizing influence [8], and the
corresponding alkyl derivatives can display low thermal
stability and high sensitivity to oxygen and moisture.
Another potential problem is the reactivity of some
nitrogen ligands, such as the imines, to the Li or Mg
Nickel alkyl complexes play a central role in several
catalytic transformations of great economic importance,
such as ethylene dimerization or oligomerization [1]. In
these processes, the insertion of two or more ethylene
molecules into a nickel hydride or alkyl bond, followed
by a chain transfer reaction (either b-hydride elimina-
tion or direct chain transfer to the monomer), leads to
the formation of a-olefins. The molecular weight of the
products is determined by the relative rates of the olefin
insertion and chain transfer steps, which in turn are
influenced by the reaction pressure and temperature and
by the structure of the catalyst.
As shown by Brookhart and co-workers [2], nitrogen
ligands containing bulky substituents (e.g. a-diimines
* Corresponding author. Tel.:
4460565.
E-mail address: campora@iiq.csic.es (J. Ca´mpora).
ꢁ
/
34-95-4489555; fax:
ꢁ/34-95-
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00691-0

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
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221
reagents used to transfer the alkyl groups to the metal
center. For instance, the alkylation of the a-diimine
nickel dibromide complexes Ni(NÃN)Br2 with MeLi or
/
Mg(CH2SiMe3)Cl, reported by Brookhart and co-work-
ers [2] and Okuda and co-workers [9] respectively, leads
to the desired alkyl complexes in low yields, usually
below 30%. This can represent a serious drawback for
the use of alkyl complexes in catalyst screening proto-
cols. In contrast, ligand exchange reactions, starting
from suitable precursors of the type MR2L2?; provide a
smooth and selective method for the preparation of the
desired Ni and Pd alkyl complexes. In order to be
synthetically useful, the precursor must contain labile L?
ligands, and at the same time, it should be readily
available and display a reasonable stability. Several
complexes of Ni and Pd have been used as precursors in
the synthesis of alkyl compounds. Thus, the dimethyl
Scheme 1.
1b [13] and CH2C6H4-o-Me [15], have been previously
isolated and characterized. As shown in Scheme 1, the
same general procedure allows for the preparation of the
related complexes 1aꢂ
/
e (Ni) and 2aꢂc (Pd). In most
/
derivatives MMe2(tmed) (Mꢀ
/
Ni [10], Pd [11]; tmedꢀ
/
cases organomagnesium reagents were used as alkylat-
ing reagents, but the methyl derivatives were prepared
from LiMe. The new compounds were isolated as
crystalline solids, soluble in hydrocarbon solvents and
very sensitive to oxygen. Although the products were
isolated in spectroscopically pure form (as seen by
NMR), only in some cases (1e and 2b) it has been
possible to obtain accurate analytical data, probably
because of the relatively low thermal stability of these
complexes. Thus, most MR2py2 compounds decompose
slowly in solution at room temperature in the absence of
added pyridine.
N,N,N?,N?-tetramethylethylenediamine) display good
thermal stability, and the tmed is readily displaced by
stronger ligands, such as phosphines or bipyridyl. Canty
has
proposed
the
dimethyl
complexes
[PdMe2(C4H4N2)2]2 and PdMe2(SMe)2 for the prepara-
tion of various dimethylpalladium derivatives contain-
ing chelating nitrogen donors [12].
Some years ago, our research group reported the
synthesis of the nickel bis(trimethylsilyl) complex
Ni(CH2SiMe3)2py2, (1b), which contains labile pyridine
as the only stabilizing ligand [13]. Compound 1b is
obtained in good yields from the readily available
complex NiCl2py4, and undergoes facile ligand displace-
ment reactions with phosphine, bipyridyl, tmed, etc.
Therefore, it constitutes a useful starting material for
ligand exchange reactions. More recently, we have
found that the air stable palladium metallacycle
While the Pd complexes 2 are in general somewhat
more stable than their Ni counterparts, 1, the thermal
stability of these compounds is mainly determined by
the nature of the group R. Thus, the mesityl 1e and the
trimethylsilyl derivatives 1b and 2b are fairly stable in
solution and can be stored in solid form for several
weeks at 0 8C. On the contrary, the dimethyl complexes
1a and 2a decompose slowly at room temperature both
in solution and in the solid state. As found previously
[16,17], the bis(neophyl) complex 1d is very unstable and
decays in solution within a few hours at room tempera-
ture (vide infra). Despite this, we have succeeded in
isolating it as a red crystalline solid, and its identity has
been confirmed by its transformation into the known
compound Ni(CH2CMe2Ph)2(bipy) [13] (see Section 4).
Compounds 1 and 2 exist in solution as a single
isomer. Their NMR spectra consist of a single set of
signals for the pyridine ligands and another for the alkyl
groups, whose relative intensities agree with the compo-
sition MR2py2. The signals corresponding to the pyri-
ꢀ
ꢁ
Pd(CH2CMe2-o-C6H4) (cod); (14), undergoes facile li-
gand substitution reactions [14]. In this contribution, we
extend these previous results, and report the synthesis of
a
series of complexes of composition MR2py2
(MꢀNi, Pd), including the nickelacycle
/
ꢀ
ꢁ
NiCH2CMe2-o-C6H4(py)2; (4). In addition, we describe
the use of these compounds for the preparation of
dialkyl and metallacyclic complexes that contain nitro-
gen-based ligands, such as a-diimines and 2-imidoylpyr-
idines that are relevant in polymerization catalysis.
2. Results and discussion
1
dine protons appear broad in the H-NMR spectra of
2.1. Dialkyl complexes MR2py2
the nickel complexes 1aꢂe and the palladium derivative
/
2a, presumably due to a fast, associative exchange with
traces of the free ligand, that may result from the partial,
irreversible decomposition of the complexes. From the
readiness with which this process occurs, the following
The alkylation of NiCl2py4 with organomagnesium
reagents in the presence of an excess of pyridine is
known to lead to dialkyl derivatives of composition
NiR2py2. Two compounds of this type, RꢀCH2SiMe3,
/

222
J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ239
/
order of stability can be proposed: Rꢀ
/
CH2CMe2PhB
/
resonances at d 3.29 and 2.27 ppm for 1e, and 3.34 and
2.28 ppm for 1e?), the spectra show broad pyridine
signals in the case of 1e but sharp, well defined
resonances for 1e?, indicating that the ligand exchange
is slower in the latter. Pure samples of 1e in C6D6 show
no indication of isomerization after 24 h at 20 8C.
The identity of the major product, 1e, has been
ascertained by an X-ray diffraction study (vide infra)
that reveals that this compound has a cis geometry.
Hence it can be assumed that compound 1e? corresponds
to the trans isomer. The relative slowness of the pyridine
exchange process for the latter compound could be
attributed to the absence of the trans labilizing effect
that the aryl groups exert in the cis isomer.
MeBCH2PhBCH2SiMe3Bmesityl. The exchange pro-
/
/
/
cess is very fast, and for the dimethyl complexes 1a and
2a, the NMR signals of the pyridine ligands are broad
even at ꢃ80 8C. Although the configuration of these
/
complexes cannot be deduced from the NMR data, the
known compound 1b exhibits a cis disposition in the
solid state [13], and the same configuration is observed
in the crystal structure of the nickel benzyl complex (1c),
shown in Fig. 1. Therefore, it seems reasonable that all
these MR2py2 complexes display a cis geometry, avoid-
ing in this way the mutual trans influence of the two
alkyl groups.
The reaction of Mg(2,4,6-C6H2Me3)Br with NiCl2py4
in the presence of an excess of pyridine is somewhat
more complex since, in addition to the expected complex
1e, smaller amounts of two other species, 1e? and 3 are
also formed (approximate ratio 1e:1e?:3 of 6:1:1.5,
Scheme 2). The main product, 1e, and the sparingly
soluble 3 have been isolated by fractional crystallization.
However, it has not proved possible to isolate a pure
sample of 1e?, since it always co-crystallizes with
variable amounts of 1e. In the absence of added
pyridine, the formation of 1e? is suppressed, and the
isolated yield of 1e is improved (ca. 50%).
2.2. Crystal structure of compounds 1c and 1e
Figs. 1 and 2 show the crystal structures of the benzyl
and mesityl complexes 1c and 1e. Selected bond
distances and angles are collected in Tables 2 and 3.
Complex 1c crystallizes in the monoclinic system, space
group C2/c, and the unit cell contains four equivalent
molecules. These display a slightly distorted square
planar geometry with the pyridine and benzyl ligands
arranged in a cis fashion. In order to minimize steric
interactions, the benzyl groups project themselves in
opposite directions, resulting in a general disposition
that is reminiscent of the previously reported compound
1b [13]. As observed in the latter, the pyridine rings are
tilted by 51.38 with respect to the coordination plane.
The benzyl ligands display a h1 coordination mode.
Although some h1-benzyl complexes of Ni can display
Analytical and NMR data for compound 3 demon-
strate that it is the monoaryl complex trans-Ni(2,4,6-
C6H2Me3)Br(py)2, resulting from the partial arylation of
NiCl2py4 by the bulky organomagnesium reagent. Thus,
1
the H-NMR spectrum of 3 reveals the presence of one
mesityl group and two equivalent pyridine ligands
(Table 4). Naturally, the pyridine ligands appear
equivalent in the 13C{1H} spectrum. Complex 3 can be
selectively prepared by reacting 1e with one equivalent
small NiÃ
/
CH2Ã
/
Ph angles [18] (B1008), these are 109.5
/
and 116.18 in 1c, close to the ideal tetrahedral values.
The remaining metric parameters of this molecule are as
expected, and merit no further discussion.
of HNEtꢁ3 Brꢃ:
/
NMR studies of the 1e plus 1e? mixtures reveal their
isomeric nature. Each isomer displays characteristic
signals for the mesityl and pyridine ligands in a 1:1
ratio. Apart from the different chemical shifts of their
related signals (e.g. the o- and p-Me groups give rise to
Crystals of 1e are orthorhombic, space group
P212121, and contain two crystallographically inequiva-
lent molecules. The crystal packing leaves wide channels
along the a axis, that are occupied by disordered
molecules of solvent. The two molecules adopt a cis
configuration, and have a similar fourfold propeller
shape (Fig. 2), although they display significant differ-
ences in the relative orientation of the pyridine and
mesityl ligands. A comparison of the structure of the
two molecules is also shown in Fig. 2. In the molecule
termed 1, the two pyridine ligands lay in planes with a
different inclination relative to the coordination plane
(65.1 and 48.08), while in the other the py rings exhibit a
more regular disposition, with values of inclination of
54.4 and 51.38, that are similar to those found in 1c. The
disposition of the mesityl units follow a similar trend,
and they are tilted by disparate angles in molecule 1
(72.2 and 67.08 relative to the coordination plane), and
more alike in molecule 2 (73.2 and 71.98).
Fig. 1. ORTEP view of compound 1c.

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
/239
223
Scheme 2.
tively. Similar interactions have been found in the nickel
Table 1
Crystal and refinement data for compounds 1c and 1e
and palladium mesityl complexes M(Mes)2(bipy) (Mꢀ
/
Ni [19], Pd [20]) and [Li(THF)4]ꢁ[NiMes3]ꢃ [21], but
are absent in other palladium [22] and platinum [23]
bis(mesityl) derivatives. The approach of the Ni and H
atoms demands a noticeable distortion of the geometry
of the metal bound Cipso atoms that allows the aryl
1c
1e (as 1e×
solv) a
C28H32N2Ni
/
Empirical formula
Formula weight
Temperature (K)
C24H24N2Ni
399.16
153(2)
455.27
213(2)
˚
Wavelength (A)
0.71073
Monoclinic
C2/c (no. 15)
0.71073
Orthorhombic
P212121 (no. 19)
group to tilt towards the axial position. The NiÃ
/Cipso
Ã
/
Crystal system
Space group
Unit cell dimensions
Cortho angles consistently display two different values in
each mesityl ligand, ca. 116 and 1278. It is very likely
˚
a (A)
24.360(4)
9.606(2)
20.128(4)
90
8.092(6)
23.238(14)
20.128(4)
90
that the Ni×
/
×
/
×
/
H contacts represent true bonding (‘re-
˚
b (A)
mote agostic’ [24]) interactions that compensate for the
energetically unfavorable distortion of the Ni-mesityl
linkage.
˚
c (A)
a (8)
b (8)
g (8)
118.118(3)
90
90
90
3
˚
V (A )
4154.0(13)
8
1.276
5294(6)
8
2.3. Formation of the metallacycle 4
Z
Dcalc (g cmꢃ3
Absorption coefficient (mmꢃ1
F(000)
)
1.142
0.748
1936
Although metallacyclic complexes can be regarded as
a special class of dialkyl complexes, their higher stability
[25] makes them especially attractive as starting materi-
als. Thus, we have recently shown that the metallacycles
)
0.944
1680
Crystal size (mm)
U Range (8)
Index ranges
0.2ꢄ
2.78ꢂ
225
295
65l 5
/
0.2ꢄ
23.32
h 5
k 5
/
0.1
0.6ꢄ
1.92ꢂ
115
295
325
/
0.4ꢄ
27.00
h 5
k 5
l 5
/
0.08
/
/
ꢃ
/
/
/
22,
29,
ꢃ
ꢃ
ꢃ
/
/
/
11,
29,
ꢀ
ꢁ
ꢀ
ꢁ
PdCH2CMe2-o-C6H4(cod) and PdCH2CMe2-o-C6H4-/
ꢃ
/
/
/
/
/
/
ꢃ/
/
/22
/
/
/
32
/
(Py)2; (4), are readily available, air stable materials
that undergo facile ligand exchange reactions [14]. The
Reflections collected
Independent reflections
3941
2045
(Rint
64 656
11 555
ꢀ
ꢁ
related nickelacycle NiCH2CMe2-o-C6H4(PMe3)2 [16] is
also known to exchange PMe3 by bipyridyl or phenan-
troline, but the phosphine ligands are partially displaced
by a-diimines [26]. Thus, we set out to synthesize the
complex 4, the corresponding pyridine-containing com-
plex.
ꢀ/
0.0619)
(Rint
SADABS
ꢀ0.0451)
/
Absorption correction
Data/restraints/parameters
SADABS
2045/0/244
11 555/0/571
Final R indices [I ꢀ
/
2s(I)]
R1ꢀ/0.0631,
R1ꢀ0.0317,
/
wR2ꢀ
/
0.1108
wR2ꢀ
/
0.0674
Goodness-of-fit on F2
R indices (all data)
1.015
R1ꢀ
wR2ꢀ
0.56 and ꢃ
1.003
R1ꢀ
wR2ꢀ
0.409 0.32 and ꢃ
/0.1190,
/
0.0399,
/
0.1272
/
0.0705
0.15
Nickel [16,27] and platinum [28] bis(neophyl) com-
plexes are known to experience a thermally induced
intramolecular d-H abstraction processes leading to the
corresponding cyclometallated products with concomi-
tant elimination of PhCMe3. In the case of nickel, this
reaction seems to be limited to phosphine-containing
neophyl complexes, while the decomposition of the
bipyridyl or other nitrogen-donor derivatives is more
complex and does not allow the isolation of metalla-
cyclic products [16,17].
Largest difference peak
ꢃ3
/
/
˚
and hole (e A
)
One of the most salient features of this structure is the
presence of short contacts between the metal center and
the two of the hydrogen atoms of the ortho methyl
groups that can be observed in both molecules. The
vectors defined by each of these Ni×
/
×
/
×
/
H interactions
project themselves above and below the coordination
Workup of the mother liquors from the crystallization
of 1d allows in some instances the isolation of small
plane, completing a distorted pseudo-octahedral coor-
dination environment for the Ni atoms. The Ni×
/
×
/
×
/
H
amounts (B10% yield) of an orange crystalline mate-
/
˚
distances are 2.529 (Ni1Ã
in molecule 1, somewhat shorter than in the more
symmetric molecule 2, where the Ni2ÃH35b and Ni2Ã
H44b distances amount to 2.608 and 2.563 A, respec-
/
H7b) and 2.513 A (Ni1Ã
/
H16b)
rial, that has been identified as the metallacycle 4. The
metallation of the neophyl ligand is evidenced by the
observation in the 13C{1H}-NMR spectrum of this
compound of two quaternary (161.5 and 170.5 ppm)
/
/
˚

224
J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ239
/
Fig. 2. Crystal structure of compound 1e. (a) ORTEP view of molecule 1. (b) Comparison of the two inequivalent molecules found in the solid state
(molecule 1 full lines, molecule 2 broken lines).
originate two independent sets of signals. These display
normal line widths at room temperature, indicating that
Table 2
˚
Selected bond lengths (A) and angles (8) for compound 1c
the intermolecular ligand exchange is slow in the NMR
time scale. This behaviour contrasts with that of the Ni
Bond lengths
Ni(1)Ã
Ni(1)Ã
Ni(1)Ã
/
C(1)
C(8)
1.973(6) Ni(1)Ã
/
N(15)
C(2)
1.978(5)
1.478(11)
1.472(10)
cis-dialkyls 1aꢂe, and suggests that 4 does not undergo
pyridine-releasing decomposition processes in solution,
under ambient conditions.
/
/
1.926(7) C(1)Ã
/
/
N(21)
1.966(7) C(8)Ã
/
C(9)
Bond angles
C(1)ÃNi(1)Ã
C(8)ÃNi(1)Ã
N(15)Ã
N(21)Ã
Contrary to our expectations, the yield of compound
4 does not significantly improve when 1d is allowed to
stand at room temperature for prolonged periods of
time. Monitoring the decomposition of the latter
/
/
C(8)
88.0(3)
92.3(3)
88.2(3)
91.6(3)
C(1)Ã
C(8)Ã
Ni(1)Ã
Ni(1)Ã
/
Ni(1)Ã
Ni(1)Ã
C(8)Ã
C(1)Ã
/
N(15) 179.3(3)
N(21) 178.6(3)
/
/N(15)
/
/
/
Ni(1)Ã
Ni(1)Ã
/N(21)
/
/
C(9)
C(2)
116.1(5)
109.5(5)
/
/C(1)
/
/
1
compound by H-NMR in C6D6 at room temperature
for 18 h revealed the formation of the coupling product,
2,5-dimethyl-2,5-diphenylhexane, together with t-butyl-
benzene and minor amounts of 4 (Scheme 3). Therefore,
the decomposition of 1d is dominated by reductive
Table 3
˚
Selected bond lengths (A) and angles (8) for compound 1e (as 1e×
/solv)
Molecule 1
Molecule 2
elimination, whereas cyclometallation represents
a
minor path. The addition of a catalytic amount (ca. 5
mol%) of PMe3 to 1d significantly alters this mechanistic
scheme, leading to the quantitative formation of 4 in less
than 1 h (Scheme 3). In the practice, the preparation of 4
does not require the isolation of pure samples of 1d,
since the addition of a small amount of PMe3 to a crude
extract of the latter in hexane affords the metallacycle as
an orange microcrystalline precipitate (ca. 40% yield),
that can be used for synthetic purposes without further
purification steps. This compound is very stable and can
Bond lengths
Ni(1)Ã
Ni(1)Ã
Ni(1)Ã
Ni(1)Ã
Ni(1)Ã
Ni(1)Ã
/
C(1)
C(10)
N(1)
1.920(2)
1.913(2)
1.993(2)
1.975(2)
2.529
1.928(2)
1.921(2)
1.993(2)
1.995(2)
2.608
/
/
/
N(2)
/
H(7b)
H(16b)
/
2.513
2.563
Bond angles
C(1)ÃNi(1)Ã
C(1)ÃNi(1)Ã
C(10)Ã
N(1)ÃNi(1)Ã
C(1)ÃNi(1)ÃN(1)
C(10)Ã
Ni(1)ÃC(1)Ã
Ni(1)ÃC(1)Ã
Ni(1)Ã
Ni(1)Ã
/
/
C(10)
92.3(1)
89.6(1)
90.7(1)
89.7(1)
/
/
N(2)
/
Ni(1)Ã
/
N(1)
90.3(1)
89.5(1)
89.5(1)
90.9(1)
/
/N(2)
/
/
169.8(1)
169.9(1)
116.5(2)
126.8(2)
115.1(2)
127.6(2)
171.9(1)
174.0(1)
116.1(2)
126.9(2)
116.7(2)
127.0(2)
/
Ni(1)Ã
/
N(2)
/
/
C(2)
/
/
C(6)
/
C(10)Ã
C(10)Ã
/
C(11)
C(15)
/
/
and four methyne resonances (137.2, 123.2, 122.7 and
121.2 ppm), corresponding to the o-phenylene group.
The low symmetry of the metallacyclic fragment causes
the inequivalence of the two pyridine ligands, that
Scheme 3.

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
/239
225
be stored for weeks as a solid at 0 8C without signs of
decomposition.
The reaction of 1b with the bulkiest of the a-diimines
employed, 5d, does not proceed to completion. The
1
analysis of the reaction mixture by H-NMR allowed
The catalytic action of PMe3 on complex 1d can be
explained on the basis of the known ability of phosphine
ligands to promote the d-H abstraction process in nickel
bis-neophyl complexes [16]. As shown on Scheme 4, the
displacement of a pyridine ligand of 1d by PMe3 leads to
the unstable species 1d?, that immediately decomposes to
the known metallacycle 4? [16]. Since Ni(II) complexes
undergo very fast ligand exchange reactions, the phos-
phine can readily shift from 4? to the remaining amount
of the starting dialkyl 1d, regenerating 1d?.
the identification of the expected product, 8d, but this
could not be separated from the unreacted starting
materials. It has to be noted, however, that this
compound has been prepared in ca. 18% yield by
reacting NiBr2×
/
5d with Me3SiCH2MgCl [9]. Incomplete
displacement of pyridine was also observed when the
palladium methyl and trimethylsilyl complexes 2a and
2b were reacted with the a-diimine 5c. The dimethyl
palladium derivative 9a could be isolated in analytically
pure form in 65% yield, but in the case of the
trimethylsilyl complex, incomplete conversion, and
similar solubility properties of reagents and products
prevented isolation of a pure sample of compound 9b.
The behaviour of the nickel benzyl complex 1c differs
from that of 1a and 1b, since its reaction with the a-
diimines 5c or 5d leads to dark red solutions from which
no products could be isolated. Nevertheless, it provides
the known compound 13 [29] when it is allowed to react
with N,N,N,N-tetramethylethylenediamine (Scheme 6).
The reaction of the nickel metallacycle 4 with the a-
diimines 5a and 5c affords the substitution products 15a
and 15b in high yield (Scheme 7). The NMR spectra of
15b display, in addition to the expected resonances, an
additional group of signals that are identical to those of
a pure sample of the ligand 5c. The analytical data for
this compound confirm the existence of half a molecule
of the mentioned ligand. This crystalline adduct is
obtained independently of the reagent ratio employed
in its synthesis, and therefore an excess of 5c must be
used in order to complete the pyridine displacement
reaction. When a stoichiometric (1:1) reagent ratio is
used, the co-crystallization of 15b and 5c removes the
latter from the equilibrium mixture, leading to decreased
yields of the product.
2.4. Synthesis of dialkyl and metallacyclic complexes
containing bidentate nitrogen ligands
Brookhart and co-workers [2] and Okuda and co-
workers [9] have reported that the alkylation of nickel
and palladium halocomplexes containing a-diimine
ligands with organomagnesium reagents leads to the
formation of the corresponding dialkyl derivatives. In
this way, these authors have prepared the dimethyl and
bis(trimethysililylmethyl)nickel complexes (7aꢂ
8aꢂ8d, see Scheme 5), albeit in low yield. We have
investigated the reaction of some of the nickel and
palladium complexes 1 and 2 with the a-diimines 5aꢂ5d
/7d and
/
/
and the 2-imidoylpyridines 6a, b. As shown in Scheme 5,
the a-diimine ligands displace the pyridine from the
nickel dimethyl complex 1a, affording the blue products
7aꢂd in greater than 90% isolated yield. Similarly,
/
complex 1b reacts cleanly with the a-diimine ligands
affording the corresponding trimethylsilylmethyl deri-
vatives 8aꢂc as green crystalline solids in ca. 90%
/
isolated yield. Therefore, this reaction provides an
improved method for the synthesis of this type of nickel
complexes. Full spectroscopic and analytical data have
been collected for the seven derivatives.
The palladium analogue of 4 has also been reported
recently [14], but since it is prepared from the more
reactive 1,5-dicyclooctadiene derivative, 14, we chose to
examine the ligand displacement reactions of the latter
compound. As shown on Scheme 7, the cyclooctadiene
ligand is readily replaced by the a-diimine ligand 5aꢂ
/
d,
affording the corresponding metallacycles in nearly
quatitative yields as red or brown solids.
The Ni complexes of 2-imidoylpyridine have been
recently shown to induce good levels of activity in the
oligomerization of ethylene [30]. These ligands can be
considered to occupy an intermediate position between
the a-diimines and 2,2?-bipyridyl. Our results are in
consonance with this trend, since 6a and 6b react with
MR2py2 (MꢀNi or Pd), and with the metallacycles 4
/
and 14, affording the corresponding organometallic
derivatives in quantitative yields (Schemes 5 and 7).
The properties of the dark green (Ni) or red (Pd)
complexes of 2-imidoylpyridines are similar to those of
Scheme 4.

226
J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ239
/
Scheme 5.
substituents of the imino nitrogen atom can not rotate
freely, as deduced from the diastereotopic character of
the isoproyl methyl groups of the complexes that
contain the ligand 6b. However, the lower symmetry
of the 2-imidoylpyridine ligands causes the inequiva-
lence of the two alkyl ligands. The complexes that
contain the unsymmetrical metallacyclic unit exist in
solution as a mixture of isomers. As the isomer ratio is
found to be approximately constant from one sample to
another, these isomers exist in solution as equilibrium
mixtures, their mutual interconversion process being
slow in the NMR timescale. A combined study of their
2D-NOESY and COSY spectra, as well as bidimen-
Scheme 6.
sional HÃ
/
C heterocorrelations has allowed full assign-
ment of the 1H- and 13C{1H}-NMR signals of each
isomer. The relative disposition of the ligands has been
determined on the basis of the NOE relationships found
in the NOESY spectra, as sketched on Fig. 3.
Scheme 7.
their a-diimine counterparts, displaying comparable
sensitivity toward atmospheric agents and similar solu-
bility in hydrocarbon or ethereal solvents, from which
they can be crystallized. The NMR spectra of the dialkyl
derivatives of ligands 6a and 6b show many analogies
with those of a-diimine complexes. For instance, in spite
of their relatively lower steric encumbrance, the aryl
Fig. 3.

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
/239
227
3. Conclusions
diene ligand of the metallacycle 14 is readily displaced
by a-diimines and 2-imidoyl pyridines, providing a facile
method for the preparation of many organometallic
complexes of palladium containing these ligands.
The reactions of NiCl2py4 or PdCl2py2 with organo-
magnesium or organolithium reagents allow the synth-
esis of dialkyl complexes of composition cis-MR2py2
(MꢀNi, 1; Pd, 2). In general, these compounds are very
/
sensitive to oxygen and display limited thermal stability,
but can be handled at room temperature for limited
periods of time. The nickel neophyl derivative 1d can be
readily converted into the metallacyclic species 4 by the
action of catalytic amounts of PMe3. Complex 4 is
considerably more stable than the open-chain dialkyl
compounds, and can be stored for longer periods of
time.
Chelating nitrogen ligands can displace the pyridine
ligands of the Ni complexes, allowing the direct, high
yield preparation of dialkyl and metallacyclic derivatives
stabilized by relatively poor donors such as the a-
diimines. However, this methodology finds some limita-
tions, as a combination of bulky alkyl and a-diimine
ligands can lead to incomplete reactions. The displace-
ment of the pyridine ligands by a-diimines is less
favoured in the case of the Pd derivatives, where it
generally leads to equilibrium mixtures. However, both
4. Experimental
Microanalyses were performed by the Analytical
Service of the Instituto de Investigaciones Qu´ımicas.
The spectroscopic instruments used were Bruker Model
Vector 22 for IR spectra, and Bruker DPX-300, DRX-
400 and DRX-500 for NMR spectroscopy. The 13C
resonance of the solvent was used as an internal
standard, but chemical shifts are reported with respect
to SiMe4. The 13C{1H}-NMR assignments were helped
in most cases with the use of gated decoupling and two
dimensional techniques. 31P{1H}-NMR shifts are refer-
enced to external 85% H3PO4. All preparations and
other operations were carried out under oxygen-free
nitrogen by conventional Schlenk techniques. Solvents
were dried and degassed before use. The petroleum ether
used had a boiling point of 40ꢂ
/
60 8C. The compounds
NiCl2py4 [31a], PdCl2py2
[31b] and
types of MR2py2 compounds (MꢀNi or Pd) find
/
ꢀ
ꢁ
Pd(CH2CMe2-o-C6H4) (cod) [3] were prepared accord-
application for the preparation of derivatives of stronger
ligands, such as the 2-imidoylpyridines. The cycloocta-
ing to literature methods.
Table 4
1H-NMR data for complexes 1aꢂ
/
d, 3 and 4 a
R
CHar(py)
CH2
Me
CHar
Ni(Me)2py2 (1a)
0.20 (bs, 6H)
6.28 (bs, 4H, CH(3))
6.64 (bs, 2H, CH(4))
8.56 (bs, 4H, CH(2))
Ni(CH2Ph)2py2 (1c)
2.25 (s, 4H)
6.87 (d, 4H, 7.0, o-CH)
6.93 (t, 2H, 7.0, p-CH)
6.99 (t, 4H, 7.0, m-CH)
6.82 (bs, 4H, m-CH)
6.98 (bs, 2H, p-CH)
7.62 (bs, 4H, o-CH)
6.73 (s, 4H, m-CH)
6.28 (tm, 4H, 6.3, CH(3))
6.64 (tm, 2H, 7.6, CH(4))
8.13 (bs, 4H, CH(2))
Ni(CH2CMe2Ph)2py2 (1d)
cis-Ni(2,4,6-C6H2Me3)2py2 (1e)
trans-Ni(2,4,6-C6H2Me3)2py2 (1e?)
Ni(2,4,6-C6H2Me3)Brpy2 (3) b
1.17 (bs, 4H) 1.85 (bs, 12H)
6.26 (bs, 4H, CH(3))
6.69 (bs, 2H, CH(4))
8.00 (bs, 4H, CH(2))
6.16 (bs, 4H, CH(3))
2.27 (s, 6H, p-Me)
3.29 (s, 12H, o-Me)
6.63 (bs, 2H, CH(4))
8.10 (bs, 4H, CH(2))
2.28 (s, 6H, p-Me)
3.34 (s, 12H, o-Me)
6.82 (s, 4H, m-CH)
6.32 (s, 2H, m-CH)
6.35 (tm, 2H, CH(4))
5.89 (tm, 4H, CH(3))
8.45 (dm, 4H, CH(2))
7.00 (t, 4H, 6.8, CH(3))
7.47 (t, 2H, 7.5, CH(4))
8.84 (bd, 4H, CH(2))
6.24 (tm, 2H, 6.4, CH(3))
6.33 (tm, 2H, 6.3, CH(3))
6.63 (tm, 1H, 7.6, CH(4))
6.70 (tm, 1H, 7.6, CH(4))
8.43 (dm, 2H, 4.8, CH(2))
8.67 (dm, 2H, 4.7, CH(2))
1.99 (s, 3H, p-Me)
3.37 (s, 6H, o-Me)
ꢀ
ꢁ
/
Ni(CH2CMe2-o-C6H4)py2 (4)
1.76 (s, 2H)
1.91 (s, 6H)
6.42 (d, 1H, 7.2, o-CH)
6.99 (t, 1H, 7.1, m-CH)
7.17ꢂ7.27 (m, 2H, o-, m-CH)
/
a
C6D6, d (J, Hz).
CD2Cl2.
b

228
J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ239
/
Table 5
13C{1H}-NMR data for complexes 1aꢂd, 3 and 4 a,b
/
R
CarH(py)
CH2
CÃ/Me
CarH
Car
Ni(Me)2py2 (1a)
ꢃ
/
5.1
123.4 (CarH(3))
134.3 (CarH(4))
150.1 (CarH(2))
123.2 (CarH(3))
134.4 (CarH(4))
149.8 (CarH(2))
123.8 (CarH(3))
133.6 (bs, CarH(4))
149.5 (bs, CarH(2))
123.1 (CarH(3))
134.9 (CarH(4))
151.2 (CarH(2))
122.2 (CarH(3))
134.0 (CarH(4))
154.0 (CarH(2))
123.8 (CarH(3))
137.0 (CarH(4))
153.4 (CarH(2))
123.5 (CarH(3))
123.6 (CarH(3))
134.6 (CarH(4))
135.0 (CarH(4))
149.9 (CarH(2))
150.8 (CarH(2))
Ni(CH2Ph)2py2 (1c)
23.2
28.9
120.6
122.1
128.7
125.4
125.9
127.4
125.7
144.0
Ni(CH2CMe2Ph)py2 (1d)
cis-Ni(2,4,6-C6H2Me3)2py2 (1e)
trans-Ni(2,4,6-C6H2Me3)2py2 (1e?)
Ni(2,4,6-C6H2Me3)Brpy2 (3)
34.0 (CÃ
41.7 (C Ã
/
Me)
/
Me)
20.6 (p-Me)
27.9 (o-Me)
130.1
143.4
154.2
131.5
142.0
174.6
133.0
140.9
148.0
161.8
170.5
20.8 (p-Me)
24.9 (o-Me)
136.3
126.6
20.3 (p-Me)
23.9 (o-Me)
ꢀ
ꢁ
/
Ni(CH2CMe2-o-C6H4)py2 (4)
44.2
34.7 (CÃ
48.2 (C Ã
/Me)
121.2 (o-CarH)
122.7 (m-CarH)
123.2 (m-CarH)
137.2 (o-CarH)
/
Me)
a
C6D6, d (J, Hz).
Singlets, unless otherwise indicated.
b
4.1. Synthesis of Ni(Me)2py2 (1a)
To a cooled (ꢃ60 8C) suspension of Ni2Cl2py4 (1.60
extracted with 40 ml of toluene and filtered. After
addition of 0.5 ml of py, the solvent was partially
evaporated and some petroleum ether added. Cooling to
/
g, 3.6 mmol) in 40 ml of Et2O were added 1 ml of py and
4.5 ml (7.2 mmol) of a 1.60 M solution of MeLi in Et2O.
The mixture was stirred 20 min at this temperature and
10 min at room temperature (r.t.), during which time the
colour of the suspension turned dark green. The
reaction mixture was taken to dryness and the residue
ꢃ
/
30 8C, provided red crystals of complex 1a in 50ꢂ
/
55%
yield.
The compound Pd(Me)2py2 (2a) was similarly
prepared, from PdCl2py2 as starting material,
and isolated as white crystals in 45ꢂ
yield.
/
50%
Table 6
1H-NMR data for complexes 2aꢂ
/
c a
R
CHar(py)
CH2
Me
CHar
Pd(Me)2py2 (2a)
0.20 (bs, 6H)
6.28 (bs, 4H, CH(3))
6.64 (bs, 2H, CH(4))
8.56 (bs, 4H, CH(2))
Pd(CH2SiMe3)2py2 (2b)
Pd(CH2Ph)2py2 (2c)
ꢃ
/
0.20 (s, 4H)
0.06 (s, 18H)
6.34 (tm, 4H, 7.0, CH(3))
6.62 (tm, 2H, 7.0, CH(4))
8.81 (dm, 4H, 6.5, CH(2))
6.32 (bs, 4H, CH(3))
3.12 (s, 4H)
6.90 (t, 4H, 6.7, m-CH)
7.04 (t, 2H, 6.7, p-CH)
7.16 (d, 4H, 6.5, o-CH)
6.67 (bs, 2H, CH(4))
8.06 (dm, 4H, 6.5, CH(2))
a
C6D6, d (J, Hz).

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
/239
229
Table 7
13C{1H}-NMR data for complexes 2aꢂ
/
c a,b
R
CarH(py)
CH2
Me
CarH
Car
Pd(Me)2py2 (2a)
ꢃ
/
5.1
123.4 (CarH(3))
134.3 (CarH(4))
150.1 (CarH(2))
123.7 (CarH(3))
134.8 (CarH(4))
153.5 (CarH(2))
123.6 (CarH(3))
135.4 (CarH(4))
150.3 (CarH(2))
Ni(CH2SiMe3)2py2 (2b)
Ni(CH2Ph)2py2 (2c)
18.6
23.6
3.0
120.5 (CarH)
127.2 (CarH)
127.7 (CarH)
153.5
a
C6D6, d (J, Hz).
Singlets, unless otherwise indicated.
b
Table 8
1H-NMR data for complexes 7aꢂ
/
d, 8aꢂ
/
c and 15a, b a
R
L
CH2
Me
CHar
R1
R2
CHar(L)
Ni(Me)2L (7a)
1.92 (s, 6H)
2.15 (s, 12H, Me)
8.66 (s, 2H)
7.16 (m, 4H, m-CH)
7.23 (t, 2H, 7.4, p-CH)
0.28 (s, 6H, Me) 7.16 (s, 6H, m,p-CH)
Ni(Me)2L (7b)
Ni(Me)2L (7c)
1.20 (s, 6H)
1.96 (s, 6H)
2.15 (s, 12H, Me)
0.96 (d, 12H, 6.9,
Me)
ꢃ
/
9.03 (s, 2H)
7.31 (d, 4H, 7.1, m-
CH)
7.40 (t, 2H, 6.1, p-CH)
1.37 (d, 12H, 6.9,
Me)
3.28 (h, 4H, 6.8, CH)
0.99 (d, 12H, 6.9,
Me)
Ni(Me)2L (7d)
1.09 (s, 6H)
ꢃ/0.11 (s, 6H, Me) 7.30 (m, 6H, m,p-CH)
1.42 (d, 12H, 6.7,
Me)
3.14 (h, 4H, 6.8, CH)
2.18 (bs, 12H)
Ni(CH2SiMe3)2L (8a)
2.06 (bs,
4H)
0.02 (bs,
18H)
8.56 (bs, 2H)
7.12 (d, 4H, 6.6, m-
CH)
7.22 (t, 2H, 6.7, p-CH)
7.13 (bm, 6H, m,p-CH)
Ni(CH2SiMe3)2L (8b)
Ni(CH2SiMe3)2L (8c)
0.95 (bs,
4H)
0.12 (bs,
18H)
2.16 (bs, 12H)
ꢃ
/
0.25 (bs, 6H,
Me)
0.83 (d, 12H, 6.6,Me) 9.03 (s, 2H)
2.26 (bs,
4H)
0.03 (bs,
18H)
7.31 (d, 4H, 7.5, m-
CH)
7.39 (t, 2H, 7.5, p-CH)
1.47 (d, 12H, 6.5,
Me)
3.53 (h, 4H, 5.7, CH)
ꢀ
ꢁ
/
Ni(CH2CMe2-o-C6H4)L
(15a)
4.29 (s, 2H) 1.18 (s, 6H)
6.63 (dm, 1H,
7.4)
6.84 (tm, 1H, 7.4) 2.15 (s, 6H, Me)
2.14 (s, 6H, Me)
8.19 (s, 1H)
8.30 (s, 1H)
7.05 (d, 2H, 7.5, m-
CH)
7.07 (d, 2H, 6.8, m-
CH)
7.01 (tm, 1H, 7.4)
8.15 (dm, 1H,
7.3)
7.14 (m, 1H, p-CH)
7.19 (t, 1H, 7.5, p-CH)
ꢀ
ꢁ
/
Ni(CH2CMe2-o-C6H4)L
(15b)
4.32 (s, 2H) 1.16 (s, 6H)
6.61 (dm, 1H,
7.1)
0.94 (d, 6H, 6.8, Me) 8.44 (s, 1H)
7.24 (d, 4H, 7.8, m-
CH)
6.80 (tm, 1H, 6.9) 0.99 (d, 6H, 6.8, Me) 8.58 (s, 1H)
6.89 (tm, 1H, 7.1) 1.14 (d, 6H, 6.8, Me)
7.30 (t, 1H, 7.6, p-CH)
7.36 (t, 1H, 7.7, p-CH)
8.12 (dm, 1H,
7.7)
1.35 (d, 6H, 6.8, Me)
3.39 (h, 2H, 6.8, CH)
3.49 (h, 2H, 6.8, CH)
a
C6D6, d (J, Hz)

Table 9
13C{1H}-NMR data for complexes 7aꢂ
/
d, 8aꢂ
c and 15a, b a,b
/
R
L
CH2 CÃ
/
Me
CarH, Car
R1
R2Ã
154.6 (HÃ
/
CÄ/N
CarH (L)
Car (L)
Ni(Me)2L (7a)
Ni(Me)2L (7b)
Ni(Me)2L (7c)
ꢃ
/
6.9
5.3
6.7
18.4 (Me)
/
C Ä
/
N)
125.9 (p-CarH)
127.9 (m-CarH)
125.6 (p-CarH)
128.2 (m-CarH)
123.3 (m-CarH)
126.8 (p-CarH)
128.2 (o-Car)
153.6 (Car)
ꢃ/
18.3 (Me)
19.9 (Me Ã
164.1 (MeÃ
154.3 (HÃC Ä
/
CÄ
C Ä
N)
/
N)
129.2 (o-Car)
149.2 (Car)
/
/N)
ꢃ/
23.1 (Me)
24.1 (Me)
28.5 (CH)
23.1 (Me)
23.4 (Me)
28.5 (CH)
19.1 (Me)
/
/
139.1 (o-Car)
150.9 (Car)
Ni(Me)2L (7d)
ꢃ
/
4.0
20.9 (Me Ã
162.6 (MeÃ
/
CÄ
/
N)
N)
123.4 (m-CarH)
126.4 (p-CarH)
139.1 (o-Car)
147.0 (Car)
/
C Ä
/
Ni(CH2SiMe3)2L (8a)
Ni(CH2SiMe3)2L (8b)
Ni(CH2SiMe3)2L (8c)
ꢃ
/
2.0 3.2
3.2 3.9
3.4 3.1
154.0 (HÃ
/
C Ä
/
N)
126.1 (p-CarH)
128.2 (m-CarH)
125.6 (m-CarH)
128.3 (p-CarH)
123.5 (m-CarH)
126.9 (p-CarH)
128.4 (o-Car)
153.6 (Car)
ꢃ/
19.8 (Me)
18.7 (Me Ã
161.8 (MeÃ
154.3 (HÃC Ä
/
CÄ
/
N)
N)
128.7 (o-Car)
149.7 (Car)
/
C Ä
/
ꢃ/
22.7 (Me)
25.0 (Me)
/
/
N)
139.5 (o-Car)
151.0 (Car)
28.3 (CH)
ꢀ
ꢁ
/
/
Ni(CH2CMe2-o-C6H4)L (15a)
49.4 33.4 (CMe2) 120.8, 122.7, 125.8, 136.6 (CarH)
47.5 (CMe2) 150.1, 171.5 (Car)
18.2 (Me)
18.9 (Me)
155.3 (HÃ
157.1 (HÃ
156.1 (HÃ
156.6 (HÃ
/
C Ä
C Ä
C Ä
C Ä
/
N)
N)
N)
N)
126.0, 126.1 (p-CarH)
127.9, 128.3 (m-CarH)
123.3, 123.5 (m-CarH)
127.0, 127.1 (m-CarH)
128.4, 128.8 (o-Car)
152.9, 153.6 (Car)
139.3, 139.4 (o-Car)
149.8, 151.1 (Car)
/
/
ꢀ
ꢁ
Ni(CH2CMe2-o-C6H4)L (15b)
49.4 33.2 (CMe2) 120.5, 122.5, 125.4, 137.5 (CarH)
47.6 (CMe2) 150.0, 171.3 (Car)
22.2, 22.7, 24.1, 24.6 (Me)
28.4, 28.8 (CH)
/
/
/
/
a
C6D6, d (J, Hz).
Singlets, unless otherwise indicated.
b

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
/239
231
Table 10
1H-NMR data for complexes 9a and 16aꢂ
/
da
R
L
CH2
Me
0.76 (s, 6H)
CHar
R1
R2
CHar(L)
Pd(Me)2L (9a)
1.07 (d, 12H, 6.9, Me) 7.40 (s, 2H)
1.30 (d, 12H, 6.8, Me)
3.38 (h, 4H, 6.9, CH)
7.12 (m, 6H, p,m-CH)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L (16a) 2.44 (s, 2H) 1.48 (s, 6H) 6.55 (dm, 1H, 7.3) 2.09 (s, 6H, Me)
6.96 (s, 2H)
6.94 (m, 6H, p,m-CH)
6.87 (tm, 1H, 7.1) 2.15 (s, 6H, Me)
7.00 (m, 2H)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L (16b) 2.17 (s, 2H) 1.52 (s, 6H) 6.24 (dm, 1H, 7.4) 2.08 (s, 6H, Me)
1.08 (s, 3H, Me) 6.90ꢂ
/
7.07 (m, 6H, p,m-
CH)
6.87 (tm, 1H, 7.3) 2.14 (s, 6H, Me)
7.03 (m, 2H)
1.13 (s, 3H, Me)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L (16c) 2.54 (s, 2H) 1.46 (s, 6H) 6.58 (dm, 1H, 7.6) 1.06 (d, 6H, 7.6, Me) 7.33 (s, 1H)
6.82 (tm, 1H, 7.4) 1.08 (d, 6H, 7.1, Me) 7.36 (s, 1H)
6.94 (dm, 1H, 7.5) 1.16 (d, 6H, 6.8, Me)
7.18 (m, 6H, p,m-CH)
7.02 (tm, 1H, 7.3) 1.36 (d, 6H, 6.8, Me)
3.43 (h, 2H, 7.1, CH)
3.48 (h, 2H, 6.8, CH)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L (16d) 2.24 (s, 2H) 1.49 (s, 6H) 6.16 (dm, 1H, 7.5) 0.99 (d, 6H, 6.9, Me) 1.23 (s, 3H, Me) 7.09ꢂ
/
7.24 (m, 6H, p,m-
CH)
6.80 (tm, 1H, 7.4) 1.05 (d, 6H, 7.0, Me)
6.93 (dm, 1H, 7.3) 1.24 (d, 6H, 6.8, Me) 1.28 (s, 3H, Me)
7.02 (tm, 1H, 7.2) 1.43 (d, 6H, 6.8, Me)
3.21 (h, 2H, 7.3, CH)
3.26 (h, 2H, 6.9, CH)
a
C6D6, d (J, Hz).
4.2. Synthesis of Ni(CH2Ph)2py2 (1c)
ether (2ꢄ
solvent and cooling to ꢃ
crystals of complex 1d in 30ꢂ
Mother liquors provided compound 4 in 10ꢂ
yield.
/
45 ml). Filtration, partial evaporation of the
30 8C furnished dark red
35% yield.
/
One milliliter of py and 6 ml (4.02 mmol) of a 0.67 M
solution of Mg(CH2Ph)Cl in Et2O were added to a
suspension of NiCl2py4 (0.90 g, 2.01 mmol) in 40 ml of
/
/15%
Et2O cooled at ꢃ60 8C. The mixture was stirred 10 min
/
at this temperature and 30 min at r.t. The solvent was
evaporated under reduced pressure and the residue
4.4. Reaction of complex 1d with bipy
extracted with a mixture Et2Oꢂpetroleum ether 1:1, to
/
which 0.5 ml of py had been previously added. After
filtration, concentration of the solution and cooling to
A mixture of 0.45 g (0.94 mmol) of 1d and 0.15 g (0.94
mmol) of bipy was dissolved in 30 ml of Et2O and
ꢃ
/
30 8C, compound 1c was isolated as red crystals in
cooled at ꢃ20 8C and stirred at this temperature for 30
/
55ꢂ65% yield.
/
min, then the cold bath was removed and the mixture
was stirred at r.t. for 30 min. The solution was filtered
The complex Pd(CH2Ph)2py2 (2c) was identically
prepared, from PdCl2py2, and obtained as yellow
and concentrated, upon cooling to ꢃ30 8C compound
/
crystals in 50ꢂ55% yield.
/
Ni(CH2CMe2Ph)bipy [13] was obtained as green crystals
1
in 82% yield. H-NMR (C6D6, 20 8C): d 1.74 (s, 4H,
CH2); 1.88 (s, 12H, CMe2); 6.51 (t, 2H, Jꢀ
CH(4 or 5) bipy); 6.65 (d, 2H, Jꢀ7.0 Hz, CH(3) bipy);
6.80 (t, 2H, Jꢀ6.8 Hz, CH(4ꢂ5) bipy); 6.93 (t, 4H, Jꢀ
7.2, m-CHar); 6.97 (t, 2H, Jꢀ7.1, p-CHar); 7.71 (d, 4H,
Jꢀ4H, o-CHar); 8.86 (d, 2H, Jꢀ4.9 Hz, CH(6) bipy).
/
6.0 Hz,
4.3. Synthesis of Ni(CH2CMe2Ph)2py2 (1d)
/
/
/
/
A suspension of NiCl2py4 (1.34 g, 3.01 mmol) in 40 ml
/
of Et2O was cooled at ꢃ60 8C and treated with 1 ml of
/
/
/
py and 7 ml (6.02 mmol) of a 0.86 M solution of
Mg(CH2CMe2Ph)Cl in Et2O containing small amounts
of iodide. The mixture was stirred 10 min at this
temperature and 2 h at r.t. The solvent was evaporated
under vacuum and the residue extracted with petroleum
13C{1H} (C6D6, 20 8C): d 33.0 (CMe2); 34.0 (CH2); 42.3
(CMe2); 119.8 (CarH); 123.7 (CarH); 125.0 (CarH); 125.8
(double intensity, CarH); 126.8 (double intensity, CarH);
132.2 (CarH); 147.0 (CarH); 152.5 (Car); 154.6 (Car).

232
J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ239
/
4.5. Reaction of NiCl2py4 with Mg(2,4,6-C6H2Me3)Br
in the presence of added pyridine
4.6. Improved procedure for the synthesis of cis-Ni(2,4,6-
C6H2Me3)py2 (1e)
To a suspension of NiCl2py4 (0.89 g, 2.04 mmol) in 30
4.65 ml (4 mmol) of a 0.86 M solution of Mg(2,4,6-
ml of THF cooled at ꢃ
/
60 8C, 1 ml of py and 6 ml (4.08
C6H2Me3)Br in Et2O were added to a cooled (ꢃ60 8C)
/
mmol) of a 0.68 M solution of Mg(2,4,6-C6H2Me3)Br in
Et2O were added. The mixture was stirred 10 min at this
temperature and 50 min at r.t. and then taken to
dryness. The residue was extracted with a mixture
suspension of NiCl2py4 (0.89 g, 2.04 mmol) in 30 ml of
THF. The mixture was stirred 10 min at this tempera-
ture and 1 h at r.t. The solvent was removed under
vacuum and the solid residue extracted with toluene
Et2Oꢂ
tion and cooling to ꢃ
as red crystals in 15ꢂ20% yield.
Partial evaporation and cooling to ꢃ
liquors provided complex 3 as orange crystals in 8ꢂ
yield.
/
petroleum ether 4:1. After filtration, concentra-
(3ꢄ50 ml). The brown solution was filtered, and
/
/
30 8C, compound 1e was isolated
the solvent evaporated. The crude product was recrys-
tallized from a mixture toluene:Et2O 1:1. Concentration
of the deep-orange solution and cooling to
/
/
30 8C of mother
10%
/
ꢃ30 8C overnight, furnished orange-brown crystals of
/
complex 1e in 53% yield. Anal. Calc. for C28H32N2Ni:
C, 73.87; H, 7.08; N, 6.15. Found: C, 73.95; H, 7.16; N,
5.99%.
Subsequent crops were identified as mixtures of
compounds 1e? and 1e.
Table 11
13C{1H}-NMR data for complexes 9a and 16aꢂd a,b
/
R
L
CH2 CÃ
/
Me
CarH, Car
R1
R2Ã
159.7 (HÃ
/
CÄ
/
CarH, Car (L)
Pd(Me)2L (9a)
ꢃ5.4
/
22.5 (Me)
24.1 (Me)
28.2 (CH)
/
C Ä
/
N) 123.1 (m-CarH)
126.9 (p-CarH)
138.6 (o-Car)
145.4 (Car)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L (16a) 46.9 33.9
121.9, 123.7, 124.1, 134.0
(CarH)
157.6, 169.4 (Car)
17.7 (Me)
18.1 (Me)
160.5 (HÃ
/
C Ä
/
N) 126.2, 126.3 (p-
CarH)
(CMe2)
47.2
(CMe2)
160.6 (HÃ
/
C Ä
/
N) 127.5, 128.2 (m-
CarH)
127.6, 128.3 (o-Car)
148.1, 148.9 (Car)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L
46.4 34.0
121.6, 123.3, 123.6, 134.0
(CarH)
158.4, 169.0 (Car)
17.6 (Me)
17.9 (Me)
17.5 (Me Ã
/
CÄ
/
125.6, 125.7 (p-
CarH)
(16b) c
(CMe2)
47.0
(CMe2)
N)
168.4 (MeÃ
N)
/
C Ä
/
128.2, 128.4 (m-
CarH)
168.8 (MeÃ
/
C Ä
/
126.9, 138.8 (o-Car)
N)
145.9, 146.7 (Car)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L (16c) 46.9 33.7
121.8, 123.5, 124.0, 134.8
(CarH)
22.2, 22.6, 23.8, 24.3
(Me)
160.2 (HÃ
/
C Ä
/
N) 123.2, 123.4 (p-
CarH)
(CMe2)
47.5
(CMe2)
156.8, 169.3 (Car)
28.1, 28.5 (CH)
160.5 (HÃ
/
C Ä
/
N) 127.2, 128.0 (m-
CarH)
138.5, 138.8 (o-Car)
145.9, 146.9 (Car)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L (16d) 46.3 33.8
121.4, 123.0, 123.4, 134.9
(CarH)
157.5, 169.4 (Car)
22.8, 23.1, 23.3, 23.4
(Me)
28.4, 28.8 (CH)
19.0 (Me Ã
/
CÄ
CÄ
C Ä
C Ä
/
123.4, 123.7 (p-
CarH)
(CMe2)
N)
47.3
(CMe2)
19.5 (Me Ã
/
/
127.0, 128.1 (m-
CarH)
N)
168.5 (MeÃ
N)
/
/
137.7, 137.8 (o-Car)
169.0 (MeÃ
N)
/
/
143.6, 144.5 (Car)
a
b
c
C6D6, d (J, Hz).
Singlets unless otherwise indicated.
CD2Cl2.

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
/239
233
Table 12
1H-NMR data for complexes 10a, b, 11a, b and 12 a
R
L
CH2
Me
R1, HÃ
/
CÄ/N
CHar (L)
Ni(Me)2L (10a)
1.08 (s, 3H)
1.23 (s, 3H)
2.13 (s, 6H, Me)
7.99 (s, 1H, HÃCÄN)
6.58 (d, 1H, 6.8, CH(3))
6.88 (m, 1H, CH(4 or 5))
7.05 (m, 3H, m-y p-CH)
7.10 (t, 1H, 7.4, CH(4 or 5))
9.63 (sa, 1H, CH(6))
/
/
Ni(Me)2L (10b)
1.08 (s, 3H)
1.22 (s, 3H)
0.94 (d, 6H, 6.9, Me)
1.32 (d, 6H, 6.8, Me)
3.28 (h, 2H, 6.8, CH)
6.58 (d, 1H, 7.6, CH(3))
6.88 (t, 1H, 6.0, CH(4 or 5))
7.12 (t, 1H, 7.9, CH(4 or 5))
7.23 (m, 3H, m-y p-CH)
9.63 (d, 1H, 5.3, CH(6))
6.50 (d, 1H, 7.6, CH(3))
6.86 (t, 1H, 6.0, CH(5))
7.04 (m, 3H, m-y p-CH)
7.07 (t, 1H, 7.9, CH(4))
9.51 (d, 1H, 5.5, CH(6))
6.49 (d, 1H, 7.6, CH(3))
6.87 (t, 1H, 6.6, CH(5))
7.15 (t, 1H, 8.0, CH(4))
7.21 (m, 3H, m-y p-CH)
9.46 (d, 1H, 5.5, CH(6))
6.42 (m, 1H, CH(4 or 5))
6.46 (d, 1H, 7.6, CH(3))
6.75 (t, 1H, 7.9, CH(4 or 5))
7.16 (m, 3H, m-y p-CH)
8.56 (d, 1H, 5.0, CH(6))
8.47 (s, 1H, HÃ
/
CÄ
/
N)
Ni(CH2SiMe3)2L (11a)
Ni(CH2SiMe3)2L (11b)
Pd(Me)2L (12)
0.70 (bs, 4H)
0.29 (bs, 18H)
2.20 (s, 6H, Me)
7.86 (s, 1H, HÃCÄ
/
/
N)
0.71 (s, 2H)
0.75 (s, 2H)
0.23 (s, 9H)
0.29 (s, 9H)
0.91 (d, 6H, 6.8, Me)
1.40 (d, 6H, 6.8, Me)
3.57 (h, 2H, 6.5, CH)
8.45 (s, 1H, HÃ
/
CÄN)
/
0.78 (s, 3H)
1.20 (s, 3H)
1.01 (d, 6H, 6.9, Me)
1.32 (d, 6H, 6.8, Me)
3.44 (h, 2H, 6.8, CH)
7.70 (s, 1H, HÃ
/
CÄN)
/
a
C6D6, d (J, Hz).
ꢀ
ꢁ
4.7. Synthesis of trans-Ni(2,4,6-C6H2Me3)Br(py)2 (3)
A mixture of cis-Ni(2,4,6-C6H2Me3)2(py)2, 1e, (0.89 g,
4.9. Synthesis of Ni(CH2CMe2-o-C6H4)py2 (4)
4.9.1. Method A
1.96 mmol) and HBr×
/
NEt3 (0.36 g, 1.96 mmol) was
60 8C, and stirred for 10
A solution of complex 1d (0.48 g, 1 mmol) in 95 ml of
petroleum ether was treated with 0.5 ml (0.07 mmol) of a
0.14 M solution of PMe3 in Et2O. The mixture was
suspended in 40 ml of THF atꢃ
/
min at this temperature and 2 h at r.t. An orange
precipitated was observed. The solvent was removed
under reduced pressure, and the residue washed with
stirred at r.t. for 1 h and a yellowꢂorange solid
/
precipitated. After filtration, the solid, identified as
metallacycle 4, was washed with some petroleum ether
and isolated in 93% yield. Anal. Calc. for C20H22N2Ni:
C, 68.81; H, 6.35; N, 8.02. Found: C, 68.06; H, 6.31; H,
8.02%.
hexane (2ꢄ
After centrifugation, the orange solution was concen-
trated and cooled to ꢃ30 8C, affording complex 3 in
/30 ml) and extracted with CH2Cl2 (40 ml).
/
91% yield. Anal. Calc. for C19H21BrN2Ni: C, 54.86; H,
5.05; N, 6.74. Found: C, 54.84; H, 5.24; N, 6.71%.
4.8. Synthesis of Pd(CH2SiMe3)2py2 (2b)
4.9.2. Method B
To a cooled (ꢃ
3.01 mmol) in 40 ml of Et2O, were added 1 ml of py and
ml (6.02 mmol) of 0.86 solution of
/
60 8C) suspension of NiCl2py4 (1.34 g,
One milliliter of py and 4.5 ml (4.8 mmol) of a 1.06 M
solution of Mg(CH2SiMe3)Cl in Et2O were added to a
7
a
M
cooled (ꢃ
/
60 8C) suspension of PdCl2py2 (0.80 g, 2.4
Mg(CH2CMe2Ph)Cl in Et2O which contained some
iodide. The reaction mixture was stirred 15 min at this
temperature and 30 min at r.t., then 0.5 ml (0.07 mmol)
of a 0.14 M solution of PMe3 in Et2O were added, and
stirring was continued for 1 h. The solvent was
evaporated under reduced pressure and the residue
extracted with 50 ml of Et2O. After filtration, concen-
mmol) in 30 ml of Et2O. The mixture was stirred 5 min
at this temperature and 1 h at r.t. The solvent was
stripped off and the residue extracted with 40 ml of
petroleum ether and filtered. After partial evaporation
of the solution, cooling to ꢃ
crystals of complex 2b in 50ꢂ55% yield. Anal. Calc. for
/
30 8C furnished yellow
/
C18H32N2PdSi2: C, 49.24; H, 7.35; N, 6.38. Found: C,
49.16; H, 7.50; N, 6.58%.
tration and cooling to ꢃ
isolated as orange crystals in 30ꢂ
/
30 8C, compound 4 was
35% yield.
/

234
J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ239
/
Table 13
13C{1H}-NMR data for complexes 10a, b, 11a, b and 12 a,b
R
L
CH2
Me
R1, HÃ
/
CÄ/N
CarH(L)
Car(L)
Ni(Me)2L (10a)
Ni(Me)2L (10b)
ꢃ
/
3.4
18.2 (Me)
124.1 (C(3)H), 125.7 (C(4 or 5)H)
126.2 (C(4 or 5)H), 127.8 (m-CarH)
133.6 (p-CarH), 148.2 (C(6)H)
129.2 (o-Car)
149.9 (Car)
ꢃ
/
5.0
157.3 (HÃ
/
CÄ
/
N)
154.5 (Car(2))
140.5 (o-Car)
147.1 (Car)
ꢃ
/
3.4
22.8 (Me)
24.4 (Me)
28.0 (CH)
123.1 (m-CarH), 124.2 (C(3)H)
126.3 (C(4 or 5)H), 126.6 (p-CarH)
133.8 (C(4 or 5)H), 148.4 (C(6)H)
ꢃ
/
4.0
154.1 (Car(2))
157.4 (HÃ
/
CÄ
/
N)
N)
Ni(CH2SiMe3)2L (11a)
Ni(CH2SiMe3)2L (11b)
ꢃ
2.6
/
1.1
3.0
3.9
18.8 (Me)
124.2 (C(3)H), 125.7 (C(4 or 5)H)
125.9 (C(4 or 5)H), 128.0 (m-CarH)
133.7 (p-CarH), 148.2 (C(6)H)
129.9 (o-Car)
149.8 (Car)
156.8 (HÃ
/
CÄ
/
153.5 (Car(2))
140.7 (o-Car)
147.1 (Car)
ꢃ
/
1.8
2.7
4.0
22.6 (Me)
25.2 (Me)
28.0 (CH)
123.3 (m-CarH), 124.2 (C(3)H)
125.8 (C(4 or 5)H), 126.9 (p-CarH)
133.9 (C(4 or 5)H), 148.3 (C(6)H)
1.4
153.1 (Car(2))
157.0 (HÃ
22.7 (Me)
24.3 (Me)
27.9 (CH)
/
CÄ
/
N)
N)
Pd(Me)2L (12)
ꢃ
/
6.6
123.1 (m-CH), 125.6 (C(3)H)
126.6 (C4 or 5)H), 127.3 (p-CH)
136.2 (C(4 or 5)H), 148.2 (C(6)H)
139.2 (o-Car)
145.2 (Car)
152.9 (Car(2))
ꢃ5.8
/
162.8 (HÃ
/
CÄ
/
a
C6D6, d (J, Hz).
Singlets unless otherwise indicated.
b
4.10. Synthesis of M(Me)2L (Mꢀ
MꢀPd, Lꢀ5c, 9a; MꢀNi, Lꢀ6a, b, 10a, b; Mꢀ
Lꢀ6b, 12)
/
Ni, Lꢀ
/
5aꢂ
/
d, 7aꢂ
/
d;
Compound 10a: Green. 96% yield. Anal. Calc. for
C16H20N2Ni: C, 64.26; H, 6.74; N, 9.37. Found: C,
64.21; H, 6.64; N, 9.48%.
Compound 10b: Green. 94% yield. Anal. Calc. for
C20H28N2Ni: C, 67.64; H, 7.95; N, 7.89. Found: C,
67.19; H, 7.88; N, 7.90%.
/
/
/
/
/Pd,
/
These complexes have been prepared by reacting
compounds 1a or 2a with the corresponding nitrogen
Compound 12: Red. 92% yield. Anal. Calc. for
C20H28N2Pd: C, 59.63; H, 7.01; N, 6.95. Found: C,
59.42; H, 6.70; N, 7.02%.
ligands 5aꢂd or 6a, b, following the procedure described
/
below for complex 7d:
A solution of 0.26 g (0.65 mmol) of 5d in 10 ml of
toluene was added to 0.16 g (0.65 mmol) of compound
4.11. Synthesis of M(CH2SiMe3)2L (Mꢀ
/
Ni, Lꢀ
/
5aꢂ
/
1a dissolved in 20 ml of toluene, at ꢃ20 8C. The mixture
/
c, 8aꢂc; MꢀNi, Lꢀ6a, b, 11a, b)
/
/
/
was stirred 10 min at this temperature and 1 h at r.t.,
changing the colour of the solution to deep blue. The
solvent was partially evaporated and some petroleum
The preparation of these compounds involves the
reaction of Ni(CH2SiMe3)2py2, 1b, with the appropriate
ether added. Upon cooling to ꢃ30 8C, compound 7d
/
nitrogen ligands 5aꢂc or 6a, b. A representative example
/
was obtained as deep blue crystals in 93% yield. Anal.
Calc. for C30H46N2Ni: C, 73.03; H, 9.40; N, 5.68.
Found: C, 73.03; H, 9.10; N, 5.68%.
Compound 7a: Deep blue. 90% yield. Anal. Calc. for
C20H26N2Ni: C, 68.03; H, 7.42; N, 7.93. Found: C,
67.20; H, 7.22; N, 7.98%.
Compound 7b: Deep blue. 93% yield. Anal. Calc. for
C22H30N2Ni: C, 69.32; H, 7.93; N, 7.35. Found: C,
69.08; H, 7.77; N, 7.43%.
Compound 7c: Deep blue. 90% yield. Anal. Calc. for
C28H42N2Ni: C, 72.27; H, 9.10; N, 6.02. Found: C,
71.66; H, 9.34; N, 6.19%.
of the experimental procedure to synthesize 8c is as
follows:
A solution of 0.5 g (1.30 mmol) of Ni(CH2SiMe3)2py2
in 20 ml of Et2O was cooled at ꢃ30 8C and treated with
/
0.49 g (1.30 mmol) of 5c dissolved in 15 ml of Et2O. The
mixture was stirred 15 min at this temperature and 2 h at
r.t. and then taken to dryness. The residue was extracted
with 40 ml of petroleum ether. Concentration and
cooling at ꢃ30 8C provided complex 8c as deep green
/
crystals in 96% yield. Anal. Calc. for C34H58N2NiSi: C,
66.98; H, 9.59; N, 4.59. Found: C, 66.84; H, 8.67; N,
4.68%.
Compound 9a: Red. 65% yield. Anal. Calc. for
C28H42N2Pd: C, 65.55; H, 8.25; N, 5.46. Found: C,
65.78; H, 8.09; N, 5.66%.
Compound 8a: Green. 90% yield. Anal. Calc. for
C26H42N2NiSi: C, 62.77; H, 8.51; N, 5.63. Found: C,
62.91; H, 8.44; N, 5.83%.

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
/239
235
Table 14
1H-NMR Data for complexes 17 and 18a, b a
R
L
CH2
Me
CHar
R1, HÃ
0.99 (d, 6H, 6.9, Me) 6.47 (d, 1H, 7.7), 6.60 (tm, 1H, 7.0)
/
CÄ
/
N
CHar(L)
ꢀ
ꢁ
/
Ni(CH2CMe2-o-C6H4)L (17) 2.57 (s,
2H)
1.67 (s,
6H)
6.80ꢂ7.20 (m,
/
2H)
7.02 (d, 1H, 6.8) 1.11 (d, 6H, 6.9, Me) 7.15 (m, 3H, p,m-CH)
7.20 (m, 1H)
3.64 (h, 2H, 6.8,
CH)
8.98 (d, 1H, 5.3)
8.09 (s, 1H, HÃ
/
CÄ
/
N)
ꢀ
ꢁ
/
Ni(CH2CMe2-o-C6H4)L (17?) 3.04 (s,
1.60 (s,
6H)
6.80ꢂ
/
7.20 (m,
0.90 (d, 6H, 6.7, Me) 6.54 (d, 1H, 7.6), 6.67 (tm, 1H, 7.0)
1.31 (d, 6H, 6.7, Me) 7.00 (tm, 1H, 7.6)
2H)
2H)
7.31 (tm, 1H,
7.3)
8.04 (d, 1H, 7.2) 3.47 (h, 2H, 6.8,
CH)
7.15 (m, 3H, p,m-CH)
8.16 (s, 1H, HÃ
N)
2.27 (s, 6H, Me)
/
CÄ
/
9.59 (d, 1H, 5.3)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L (18a) 2.57 (s,
2H)
1.30 (s,
6H)
5.96 (dm, 1H,
7.5)
7.13ꢂ7.17 (m, 3H, p,m-CH), 7.69 (m, 1H, CH(5))
/
6.31 (tm, 1H,
7.3)
8.46 (s, 1H, HÃ
/
CÄ
/
7.80 (dm, 1H, 6.9, CH(3)), 8.02 (tm, 1H, 7.7,
CH(4))
N)
6.63 (dm, 1H,
7.5)
8.88 (dm, 1H, 4.5, CH(6))
6.71 (tm, 1H,
7.2)
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L
(18a?)
1.67 (s,
2H)
1.18 (s,
6H)
6.73 (m, 1H)
2.29 (s, 6H, Me)
7.13ꢂ7.17 (m, 3H, p,m-CH), 7.75 (m, 1H, CH(5))
/
6.91 (m, 2H)
8.42 (s, 1H, HÃ
/
CÄ
/
7.80 (d, 1H, 6.9, CH(3)), 8.10 (tm, 1H, 7.0,
CH(4))
N)
7.53 (m, 1H)
6.58 (dm, 1H,
6.9)
9.22 (dm, 1H, 5.0, CH(6))
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L (18b) 3.02 (s,
2H)
1.81 (s,
6H)
1.02 (d, 6H, 6.9, Me) 7.05ꢂ7.25 (m, 3H, p,m-CH)
/
6.87 (tm, 1H,
5.7)
7.10 (m, 2H)
1.19 (d, 6H, 6.8, Me) 6.43 (tm, 1H, 7.7, CH(5)), 6.50 (dm, 1H, 7.7,
CH(3))
3.46 (h, 2H, 6.9,
CH)
6.77 (tm, 1H, 7.7, CH(4)), 8.44 (dm, 1H, 5.0,
CH(6))
7.71 (s, 1H, HÃ
N)
0.97 (d, 6H, 6.9, Me) 7.05ꢂ
CH(5))
/
CÄ
/
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L
(18b?)
2.40 (s,
2H)
1.68 (s,
6H)
7.20 (m, 1H)
7.31 (m, 2H)
/
7.25 (m, 3H, p,m-CH), 6.43 (tm, 1H, 7.7,
1.34 (d, 6H, 6.8, Me) 6.47 (dm, 1H, 7.7, CH(3)), 6.80 (tm, 1H, 7.7,
CH(4))
7.91 (d, 1H, 6.6) 3.45 (ph, 2H, 6.9,
CH)
9.01 (dm, 1H, 4.5, CH(6))
7.70 (s, 1H, HÃ
/
CÄ
/
N)
a
C6D6, d (J, Hz).
Compound 8b: Green. 95% yield. Anal. Calc. for
C28H46N2NiSi: C, 63.99; H, 8.82; N, 5.33. Found: C,
63.72; H, 8.78; N, 5.47%.
Compound 11a: Green. 83% yield. Anal. Calc. for
C22H36N2NiSi: C, 59.59; H, 8.18; N, 6.32. Found: C,
60.33; H, 8.21; N, 5.85%.
4.12. Synthesis of Ni(CH2Ph)2(TMED) (13)
To a solution of complex 1c (0.40 g, 2 mmol) in 35 ml
of Et2O, an excess of TMED (1 ml) was added. The
mixture was stirred at r.t. for 2 h. The solvent was
evaporated under vacuum and the residue extracted
Compound 11b: Green. 85% yield. Anal. Calc. for
C26H44N2NiSi: C, 62.52; H, 8.88; N, 5.61. Found: C,
61.81; H, 8.14; N, 5.87%.
with a mixture Et2Oꢂ
After concentration and cooling to ꢃ
13 was isolated as red crystals in 52% yield. H-NMR
/
petroleum ether 1:3 and filtered.
/
30 8C, compound
1

236
J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ239
/
Table 15
13C{1H}-NMR data for complexes 17 and 18a, b a,b
R
L
CH2 Me
CHar
R1, HÃ
/
CÄ
/
CHar(L)
Car(L)
N
ꢀ
ꢁ
/
Ni(CH2CMe2-o-C6H4)L
47.9 34.0
120.9, 121.5, 123.5, 22.3 (Me) 123.2 (m-CarH), 126.9 (C(3)H), 137.0 (C(4)H), 149.6 140.0 (o-
(17)
(CMe2)
47.7
(CMe2)
134.2 (CarH)
156.4, 170.3 (Car)
(C(6)H)
Car)
147.9 (Car)
24.6 (Me)
28.0 (CH)
153.7
(Car(2))
159.4 (HÃ
CÄN)
121.2, 123.8, 124.3, 22.7 (Me) 123.2 (m-CarH), 126.7 (C(3)H), 126.9 (C(5)H), 137.7 140.5 (o-
/
/
ꢀ
ꢁ
/
Ni(CH2CMe2-o-C6H4)L
47.3 34.2
(17?)
(CMe2)
48.7
(CMe2)
134.3 (CarH)
160.7, 170.8 (Car)
(C(4)H), 151.5 (C(6)H)
Car)
146.6 (Car)
24.8 (Me)
28.5 (CH)
153.4
(Car(2))
158.7 (HÃ
CÄN)
121.7, 123.3, 123.4, 18.7 (Me) 126.5 (p-CarH), 127.7 (C(3)H), 128.5 (m-CarH),
/
/
ꢀ
ꢁ
/
/
/
Pd(CH2CMe2-o-C6H4)L
(18a)
46.0 33.9
129.2 (o-
Car)
149.2 (Car)
(CMe2)
47.1
133.8 (CarH)
157.3, 169.6 (Car)
128.6 (C(5)H), 138.6 (C(4)H), 150.2 (C(6)H)
165.5 (HÃ
/
(CMe2)
CÄN)
/
153.6
(Car(2))
129.2 (o-
Car)
ꢀ
ꢁ
Pd(CH2CMe2-o-C6H4)L
(18a?)
44.3 33.6
122.1, 123.4, 124.1, 18.4 (Me) 126.2 (p-CarH), 127.6 (C(3)H), 128.3 (m-CarH),
128.7 (C(5)H), 138.5 (C(4)H), 151.0 (C(6)H)
(CMe2)
47.5
134.9 (CarH)
160.3, 169.3 (Car)
165.7 (HÃ
CÄN)
/
149.0 (Car)
(CMe2)
/
157.3
(Car(2))
ꢀ
ꢁ
Pd(CH2CMe2-o-C6H4)L
(18b)
46.4 34.3
121.8, 123.1, 123.3, 22.5 (Me) 123.4 (m-CarH), 126.5 (C(3)H), 126.9 (C(5)H), 127.2 139.3 (o-
(p-CarH), 136.7 (C(4)H), 151.9 (C(6)H)
(CMe2)
47.3
(CMe2)
134.6 (CarH)
157.0, 165.1 (Car)
Car)
146.7 (Car)
24.1 (Me)
28.1 (CH)
152.5
(Car(2))
162.8 (HÃ
CÄN)
122.3, 123.6, 124.0, 24.3 (Me) 123.4 (m-CarH), 126.8 (C(5)H), 126.9 (C(3)H), 136.8 138.9 (o-
/
/
ꢀ
ꢁ
/
Pd(CH2CMe2-o-C6H4)L
45.2 33.9
(18b?)
(CMe2)
48.1
(CMe2)
135.0 CarH)
160.1, 168.9 (Car)
(C(4)H), 150.9 (C(6)H)
Car)
145.7 (Car)
24.7 (Me)
27.9 (CH)
152.5
(Car(2))
164.6 (HÃ
/
CÄN)
/
a
C6D6, d (J, Hz).
Singlets unless otherwise indicated.
b
ꢀ
ꢁ
(C6D6, 20 8C): d 1.17 (s, 4H, CH2 tmed); 1.42 (s, 4H,
CH2ÃNi); 1.79 (s, 12H, Me tmed); 7.12 (t, 2H, Jꢀ6.9
Hz, p-CH); 7.26 (t, 4H, Jꢀ 7.4 Hz, m-CH); 7.73 (d, 4H,
o-CH). 13C{1H} (C6D6, 20 8C): d 12.4 (CH2Ã
Ni); 47.2
4.13. Synthesis of Ni(CH2CMe2-o-C6H4)(L)
15a, b)
/
(Lꢀ5a, c,
/
/
/
/
A solution of 0.10 g (0.29 mmol) of complex 4 in 30
ml of Et2O was treated with a solution of 5a (0.08 g, 0.31
mmol) in 10 ml of Et2O, at r.t. The mixture was stirred 1
/
(Me tmed); 58.2 (CH2 tmed); 121.0 (CH); 127.6 (CH);
129.0 (CH); 155.2 (Car).

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
/239
237
h at this temperature and filtered. After partial evapora-
tion of the solvent and cooling to ꢃ30 8C, compound
solvent was evaporated under vacuum and the residue
extracted with 40 ml of petroleum ether and filtered.
/
15a was isolated as green crystals in 87% yield. This
complex crystallizes with 0.5 molecules of Et2O. Anal.
Calc. for C28H32N2Ni: C, 73.87; H, 7.08; N, 6.15.
Found: C, 73.66; H, 6.78; N, 6.34%.
Concentration and cooling at ꢃ30 8C provided green
/
crystals of compound 17 in 68% yield. Anal. Calc. for
C28H34N2Ni: C, 73.55; H, 7.49; N, 6.13. Found: C,
73.18; H, 7.11; N, 6.17%.
Compound 15b was similarly prepared and obtained
as deep blue crystals in 90% yield (respect to the
ligand). It crystallizes with 0.5 molecules of the
ligand 5c. Anal. Calc. for C36H48N2Ni: C, 77.77;
H, 8.92; N, 5.55. Found: C, 77.57; H, 8.91; N,
5.69%.
4.16. X-ray structure determination of 1c
A crystal showing well defined faces was mounted on
a Siemens Smart CCD diffractometer equipped with a
normal focus, 2.4 kW sealed tube X-ray source (Moꢂ
/
Ka
˚
0.71067 A) operating 50 kV and 20 mA.
radiation, lꢀ
/
ꢀ
ꢁ
Data were collected over a quadrant of the reciprocal
space by a combination of three sets exposures. Each
exposure of 10 s covered 0.38 in v. The crystal to
detector distance was 6.05 cm. Coverage of the unique
set was over 92% complete to at least 238 in u. Unit cell
dimensions were determined by a least squares refine-
4.14. Synthesis of Pd(CH2CMe2-o-C6H4) (L) (Lꢀ
/
5aꢂ
/
d, 16aꢂd; Lꢀ6a, b, 18a, b)
/
/
These complexes were prepared by the reaction of
ꢀ
ꢁ
Pd(CH2CMe2-o-C6H4) (cod) with the nitrogen ligands
5aꢂd or 6a, b following the synthesis described for
compound 16d.
/
ment using reflections with I ꢀ
/
20s(I) and 68B
/
2u B
/
468. The first 50 frames were recollected at the end of the
data collection to monitor crystal decay. The intensities
were corrected for Lorentz and polarization effects. Full
matrix least-squares refinement was carried out by
minimizing w(Fo2 ꢃFc2)2: H atoms were included in their
calculated positions. Refinement on F2 for all reflec-
tions, weighted R factors (Rw) and all goodness-of-fit S
are based on F2, while conventional R factors (R)
are based on F. A summary of the fundamental crystal
and refinement data are given in Table 1. Complete
structural data have been deposited as CCDC 206445
[32]. Calculations were carried out with SMART software
for data collection [33] for data reduction and SHELXTL
[33] for structure solution and refinements.
ꢀ
ꢁ
A solution of Pd(CH2CMe2-o-C6H4) (cod) (0.34 g, 1
mmol) and 5d (0.40 g, 1 mmol) in 40 ml of Et2O was
cooled at ꢃ30 8C and stirred at this temperature for 30
/
min, then the cold bath was removed and the mixture
stirred at r.t. for 4 h. The solvent was evaporated under
reduced pressure and the residue extracted with a
mixture Et2Oꢂ
partial evaporation of the solvent and cooling to
30 8C, complex 16d was isolated as red crystals in
/petroleum ether 2:1 and filtered. After
ꢃ
/
quantitative yield. Anal. Calc. for C38H52N2Pd: C,
70.78; H, 8.30; N, 4.23. Found: C, 70.53; H, 8.49; N,
4.21%.
Compound 16a: Red. Quantitative yield. Anal. Calc.
for C28H32N2Pd: C, 66.86; H, 6.41; N, 5.57. Found: C,
66.88; H, 6.48; N, 5.62%.
Compound 16b: Yellow. Quantitative yield. Anal.
Calc. for C30H36N2Pd: C, 67.75; H, 7.06; N, 5.10.
Found: C, 68.06; H, 6.99; N, 5.29.
4.17. X-ray structure determination of 1e as tolueneꢂ
/
petroleum ether solvate 1e×solv
/
A brown plate was mounted on a Siemens/Bruker
Compound 16c: Red. Quantitative yield. Anal. Calc.
for C36H48N2Pd: C, 70.12; H, 8.03; N, 4.42. Found: C,
70.09; H, 8.27; N, 4.68%.
Compound 18a: Red. 83% yield. Anal. Calc. for
C24H26N2Pd: C, 64.22; H, 5.84; N, 6.24. Found: C,
64.30; H, 5.58; N, 6.30%.
Compound 18b: Red. 93% yield. Anal. Calc. for
C28H34N2Pd: C, 66.61; H, 6.74; N, 5.55. Found: C,
66.40; H, 6.77; N, 5.42%.
Smart CCD diffractometer equipped with a sealed tube
˚
Ka radiation, lꢀ0.71067 A, gra-
X-ray source (Moꢂ
/
/
phite monochromator) and a LT2 crystal cooling unit.
Data were collected over a complete sphere of the
reciprocal space by a combination of four sets each
606 exposures. Each exposure of l5 s covered 0.38 in v.
The crystal to detector distance was 4.45 cm. Coverage
of the unique set was over 99.7% complete to 278 in u.
Unit cell dimensions were determined by a least squares
refinement using 7653 reflections with 58B
/
2u B548.
/
ꢀ
ꢁ
4.15. Synthesis of Ni(CH2CMe2-o-C6H4) (L)/
17)
(Lꢀ
/
6b,
The data were corrected for absorption. The structure
was solved with direct methods and refined on F2 with
anisotropic displacement parameters for non-hydrogen
atoms. Aromatic H atoms were included in their
calculated positions, CH3 groups were geometrically
idealized but refined in orientations. The structure
contains two independent Ni complexes. Disordered
To a cooled (ꢃ30 8C) solution of complex 4 (0.29 g,
/
0.83 mmol) in 20 ml of Et2O was added a solution of 6b
(0.22 g, 0.83 mmol) in 10 ml of Et2O. The mixture was
stirred 10 min at this temperature and 1.5 h at r.t. The

238
J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ239
/
[6] L.K. Johnson, S. Mecking, M. Brookhart, J. Am. Chem. Soc. 118
(1999) 267.
solvent molecules (toluene/petroleum ether) were
found to be present in channels extending parallel
[7] (a) A.K. Smith, in: G. Wilkinson, F.G.A. Stone, E. Abel (Eds.),
Comprehensive Organometallic Chemistry II, vol. 9, Pergamon,
Oxford, 1995;
to a (two per unit cell, each with a net volume of
ꢃ3
˚
A
294
)
and produced very diffuse electron
densities with maximum values of 1.97 e Aꢃ3. They
were taken into account with procedure SQEEZE of
program PLATON [34] giving an electron count to 139
electrons per unit cell, equivalent to about three toluene
molecules per eight Ni complexes of one unit cell.
Crystal and refinement data are given in Table 1.
Complete structural data have been deposited as
CCDC 206446 [32]. Other programs used were those
given above [35] .
˚
(b) A.J. Canty, in: G. Wilkinson, F.G.A. Stone, E. Abel (Eds.),
Comprehensive Organometallic Chemistry II, vol. 9, Pergamon,
Oxford, 1995.
[8] (a) R.H. Crabtree, The Chemistry of the Transition Metals, 3rd
ed., J. Wiley & Sons, New York, 2001, p. 91;
(b) P. Fantucci, Comments Inorg. Chem. 13 (1992) 241.
[9] T. Schleis, T.P. Spaniol, J. Okuda, J. Heinemann, R. Mulhaupt, J.
Organomet. Chem. 569 (1998) 159.
[10] W. Kaschube, K.R. Porschke, G. Wilke, J. Organomet. Chem.
¨
355 (1988) 525.
[11] (a) J. de Graaf, J. Boersma, W.J.J. Smeets, A.-L. Spek, G. van
Koten, Recl. Trav. Chim. Pays-Bas 107 (1988) 299;
(b) J. de Graaf, J. Boersma, W.J.J. Smeets, A.-L. Spek, G. van
Koten, Organometallics 8 (1989) 2907.
Acknowledgements
[12] P.K. Byers, A. Canty, Organometallics 9 (1990) 210.
[13] E. Carmona, F. Gonza´lez, M.L. Poveda, J.L. Atwood, R.D.
Rodgers, J. Chem. Soc., Dalton Trans. (1981) 777.
[14] J. Ca´mpora, J.A. Lo´pez, P. Palma, D. del R´ıo, E. Carmona, P.
Valerga, C. Graiff, A. Tiripicchio, Inorg. Chem. 40 (2001) 4116.
[15] E. Carmona, J.M. Mar´ın, M. Paneque, M.L. Poveda, Organo-
metallics 6 (1987) 1757.
Financial support from the Direccio´n General de
Investigacio´n (MCYT) (Project BQU2000-1169),
Repsol-YPF (Project 98092, Research Contracts
for MLR and CP) and EU Research and Training
Network (HPRN-CT2000-00010) are gratefully ac-
knowledged. MMC thanks the Consejo Superior de
Investigaciones Cient´ıficas for a postdoctoral I3P con-
tract. We gratefully thank Professor Ernesto Carmona
for helpful discussions.
[16] (a) E. Carmona, P. Palma, M. Paneque, M.L. Poveda, E.
Gutie´rrez-Puebla, A. Monge, J. Am. Chem. Soc. 108 (1986) 6424;
(b) E. Carmona, E. Gutie´rrez-Puebla, M. Mar´ın, M. Paneque,
M.L. Poveda, C. Ruiz, J. Am. Chem. Soc. 111 (1989) 2883.
[17] I. Black, G.B. Young, Polyhedron 8 (1989) 585.
[18] (a) J. Ca´mpora, E. Gutie´rrez, M.L. Poveda, C. Ruiz, E. Carmona,
J. Chem. Soc., Dalton Trans. (1992) 1769;
(b) B.Y. Lee, G.C. Bazan, J. Vela, Z.J.A. Komon, J. Am. Chem.
Soc. 123 (2001) 5352.
References
[19] A. Klein, Z. Anorg. Allg. Chem. 627 (2001) 645.
[20] A. Klein, M. Niemayer, Z. Anorg. Allg. Chem. 626 (2000) 1191.
[21] R. Hay-Motherwell, G. Wilkinson, T.K.N. Sweet, M.B. Hurst-
house, Polyhedron 15 (1996) 3163.
[1] B. Cornils, W.A. Herrmann (Eds.), Applied Homogeneous
Catalysis with Organometallic Compounds, vol. 1, VCH, Wein-
heim, 1996.
[22] D. Walther, T. Dohler, K. Heubach, B. Schweder, H. Gorls, Z.
Anorg. Allg. Chem. 625 (1999) 923.
[2] (a) L.K. Johnson, C.M. Killian, M. Brookhart, J. Am. Chem.
Soc. 117 (1995) 4414;
[23] (a) A. Klein, T. Scheiring, W. Kaim, Anorg. Allg. Chem. 625
(1999) 1177;
(b) C.M. Killian, L.K. Johnson, M. Brookhart, Organometallics
16 (1997) 2005;
(b) A. Klein, H.-D. Hausen, W. Kaim, J. Organomet. Chem. 440
(1992) 207;
(c) S.A. Svejda, L.K. Johnson, J. Am. Chem. Soc. 121 (1999)
10 634;
(c) A. Klein, W. Kaim, E. Waldhor, H.-D. Hausen, J. Chem. Soc.,
Perkin Trans. 2 (1995) 2121;
(d) D.P. Gates, S.A. Svejda, E. On˜ate, C.M. Killian, L.K.
Johnson, P.S. White, M. Brookhart, Macromolecules 33 (2000)
2320.
(d) A. Klein, E.J.L. McInnes, W. Kaim, J. Chem. Soc., Dalton
Trans. (2002) 2371.
[3] (a) S.D. Ittel, L.K. Johnson, M. Brookhart, Chem. Rev. 100
(2000) 1169;
[24] M. Brookhart, M.L.H. Green, L.L. Wong, Prog. Inorg. Chem. 36
(1988) 1.
(b) L.K. Johnson, C.M. Killian, in: J. Scheirs, W. Kaminsky
(Eds.), Metallocene-based Polyolefins, vol. 1, J. Wiley & Sons,
Chichester, 1999;
[25] J. Ca´mpora, P. Palma, E. Carmona, Coord. Chem. Rev. 193-195
(1999) 207.
[26] Attempts to carry out the PMe3 exchange with the adiimines 4a
and 4c (see Scheme 4) met limited success, and led to the
corresponding metallacycles 12a and 12b in ca. 20% yield. These
results were substantially improved by addition of Pd(h5-Cp)(h3-
C3H5), a phosphine sponge.
(c) S. Mecking, Coord. Chem. Rev. 203 (2000) 325;
(d) V.C. Gibson, S.K. Spitzmesser, Chem. Rev. 103 (2003)
283.
[4] (a) R.J. Maldanis, J.S. Wood, A. Chandrasekaran, M.D. Rausch,
J.C.W. Chien, J. Organomet. Chem. 645 (2000) 158;
(b) L.C. Simon, R.S. Mauler, R.F. De Souza, J. Polym. Chem. 37
(1999) 4656.
[27] E. Carmona, M. Paneque, M.L. Poveda, E. Gutie´rrez-Puebla, A.
Monge, Polyhedron 8 (1989) 1069.
[28] D.C. Griffiths, G.B. Young, Organometallics 8 (1986) 875.
[29] E. Uhlig, W. Poppitz, Z. Anorg. Allg. Chem. 477 (1981) 167.
[30] (a) T.V. Laine, M. Klinga, M. Leskela, Eur J. Inorg. Chem. (1999)
¨
[5] (a) D. Pappalardo, M. Mazzeo, C. Pellechia, Macromol. Rapid.
Commun. 18 (1997) 1017;
(b) S. Tsuji, D.C. Swenson, R.F. Jordan, Organometallics 18
(1999) 4758;
(c) T. Schleis, J. Heinemann, T.S. Spaniol, R. Mulhaupt, R.
959;
(b) T.V. Laine, U. Piironen, K. Lappalainen, M. Klinga, E.
Mulhaupt, J. Okuda, Inorg. Chem. Commun. 1 (1998) 431.
¨
Aitola, M. Leskela, J. Organomet. Chem. 606 (2000) 112.
¨

J. Ca´mpora et al. / Journal of Organometallic Chemistry 683 (2003) 220ꢂ
/
239
239
and
[31] (a) L.M. Vallarino, W.R. Hill, J.V. Quagliano, Inorg. Chem. 4
(1965) 1508;
(b) P. Gupte, R.V. Chaudhari, J. Mol. Catal. 24 (1984) 197.
[33] SMART
and
SELXTL
;
Siemens
Energy
Automation, Inc., Analytical Instrumentation, Madison, WI,
1996.
[32] CCDC nos. 206445ꢂ
/
206446 contains the supplementary crystal-
[34] A.L. Spek. PLATON, A Multipurpose Crystallographic Tool,
Utrecht. University, Utrecht, The Netherlands, 2003.
lographic data for this paper. These data can be obtained free of
charge via: http://www.ccdc.cam.ac.uk/conts/retrieving/html (or
from the CCDC, 12 Union Road, Cambridge CB121EZ, UK; fax:
[35] Programs SMART, SAINT, SADABS, and SELXTL; Siemens Energy
and Automation, Inc., Analytical Instrumentation, Madison, WI,
1998.
ꢁ/44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).