Nickel(II) complexes with bifunctional phosphine-imidazolium ligands and their catalytic activity in the Kumada-Corriu coupling reaction

Article abstract of DOI:10.1016/j.jorganchem.2005.09.010

Zwitterionic Ni(II) complexes of type NiX₃(NCN⁺), (NCN⁺ = 1-(2-diphenylphosphinoethyl)-3-(2,4,6-trimethylphenyl) imidazolium and X = Cl, 6; Br, 7), have been prepared by addition of NCN ⁺ bromide (1a) or tetrafl

Full text of DOI:10.1016/j.jorganchem.2005.09.010

Journal of Organometallic Chemistry 691 (2006) 433–443
www.elsevier.com/locate/jorganchem
Nickel(II) complexes with bifunctional phosphine–imidazolium
ligands and their catalytic activity in the Kumada–Corriu
coupling reaction
*
*
`
Joffrey Wolf, Agnes Labande , Jean-Claude Daran, Rinaldo Poli
Laboratoire de Chimie de Coordination, 205 Route de Narbonne, 31077 Toulouse Cedex 4, France
Received 4 August 2005; received in revised form 2 September 2005; accepted 10 September 2005
Available online 18 October 2005
Abstract
Zwitterionic Ni(II) complexes of type NiX3(NCN+), (NCN+ = 1-(2-diphenylphosphinoethyl)-3-(2,4,6-trimethylphenyl)imidazolium
and X = Cl, 6; Br, 7), have been prepared by addition of NCN+ bromide (1a) or tetrafluoroborate (1b) to NiX2L, and characterised
by X-ray crystallography. They have been used as catalytic precursors in the Kumada–Corriu coupling reaction between phenylmagne-
sium chloride and 4-chloroanisole, yielding high catalytic activities. Stoechiometric deprotonation investigations did not provide clear
evidence for the formation of coordinated carbene species.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Nickel(II); Phosphine; Imidazolium; Bifunctional ligands; Kumada–Corriu reaction
1. Introduction
sis of the phosphine–imidazolium precursor of this ligand,
previously described by Nolan et al. [4] and Tsoureas
et al. [9], has been improved. We also report the preparation
and characterisation of two nickel(II) complexes containing
the phosphine–imidazolium ligand and our attempts to
characterise the species obtained by subsequent deprotona-
tion of the imidazolium moiety. Finally, preliminary results
on C–C coupling-catalysed reactions are given.
The preparation of transition metal complexes of imi-
dazolin-2-ylidenes has received an ever growing attention
over the past 10 years [1–3]. Many transition metals have
been used for this purpose, particularly palladium, nickel,
rhodium and iridium [4–30]. The main interest of these
N-heterocyclic carbene complexes, in comparison to phos-
phine complexes, resides in producing robust catalysts
which will not undergo decomposition or deactivation.
On the other hand, the incorporation of a weaker coordi-
nating unit on the same ligand should ensure a good activ-
ity for catalytic applications.
N
N
Ph 2 P
The synthesis of complexes bearing a chelating phos-
phine/N-heterocyclic carbene (P-NCN) ligand has been re-
cently described [4,9,23,31,32]. They are catalytically
active, although no thorough study has been published
yet concerning their potential in this domain.
I
2. Results and discussion
In this paper, we describe the preparation of nickel(II)
complexes bearing a chelating P-NCN ligand I. The synthe-
2.1. Ligand synthesis
*
The synthesis of salts of the previously reported phos-
phine–imidazolium cation, 1-(2-diphenylphosphinoethyl)-
Corresponding author. Tel.: +33 561333173; fax: +33 561553003.
E-mail address: labande@lcc-toulouse.fr (A. Labande).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.09.010

434
J. Wolf et al. / Journal of Organometallic Chemistry 691 (2006) 433–443
3-mesityl-imidazolium (1), has been improved. Indeed, the
first method, described by Nolan et al. [4], gives the desired
compound in only 21% overall yield (starting from N-mesi-
tylimidazole) (Scheme 1a).
The alternative procedure, developed by Tsoureas et al.
[9], involves a phosphine oxide intermediate which is re-
duced under harsh conditions, and was hardly reproducible
in our hands (Scheme 1b). Moreover, the latter method
yields the imidazolium ligand as a mixture of chloride
and bromide salts, which can prove problematic for the
synthesis of metal complexes.
Our synthetic method is based on the quaternisation of
N-mesitylimidazole (2) with 1-bromoethanol, to give (1-
hydroxyethylene-3-mesityl) imidazolium bromide (3a)
(90%). We then developed two different routes to obtain
the title compound. The first one involves mesylation of
alcohol 3a (Scheme 2).
In a first attempt, mesylate 4 was obtained in only 13%
yield. However, the presence of a bromide anion made the
imidazolium salt quite soluble in water, and most of the
product was lost in the aqueous phase during work-up.
We thus proceeded to exchange the anion with tetrafluoro-
borate, leading to the salt 3b in 96% yield. Mesylation using
3b gave us compound 4 in 88% yield, then nucleophilic sub-
stitution with KPPh2 [4] produced ligand 1b in 76% yield.
However, a drawback of this procedure is the fact that
the tetrafluoroborate anion is partially replaced by mesy-
late. A second route was thus developed to avoid this prob-
lem: the imidazolium salt was obtained via bromination of
alcohol 3a with PBr3 and subsequent nucleophilic substitu-
tion with KPPh2 (67% overall yield, starting from N-mesi-
tylimidazole) (Scheme 3).
The successful introduction of PPh2 on the brominated
intermediate allowed us to avoid the phosphine protec-
tion/deprotection sequence described in Scheme 1(iv), and
to obtain the salt with Brꢀ as the only anion.
Although compound 1a could be used directly for coor-
dination studies, pure compound 1b (without mesylate con-
tamination) was also needed in order to prepare Ni(II)
complexes bearing only chloride ligands, vide infra. It
was obtained in good yields from 1a (83%), following an
anion exchange reaction with NaBF4.
Single crystals of compounds 1a and 1b were investi-
gated by X-ray crystallography. Molecule 1a (see Fig. 1,
left) shows a hydrogen bonding interaction between the
bromide anion and the acidic imidazolium proton
˚
˚
Br
Br
N
[C(1)ꢁ ꢁ ꢁBr = 3.506(5) A, H(1)ꢁ ꢁ ꢁBr=2.561(1) A]. Selected
bond distances and angles are listed in Table 1. Such
hydrogen bonding is well known from other imidazolium
structures [33,34].
(ii)
(a)
N
N
N
Br
N
Ph2P
+
+
1
(i)
2.2. Nickel(II) complexes preparation and characterisation
N
Heating a sample of NiCl2 with 1b and NaCl, or
NiBr2(DME) with 1a, in refluxing THF led, respectively,
to the air stable complexes 6 (blue crystalline solid, 63%
yield) and 7 (green crystalline solid, 95% yield) (Scheme 4).
Both complexes gave X-ray quality crystals from slow
evaporation of acetone solutions (see Fig. 2). The metal
is bonded to three halide ligands and to the phosphorus
atom of the phosphine–imidazolium ligand, to give an
overall neutral, zwitterionic structure. Selected bond dis-
tances and angles are listed in Table 2.
(iii)
Br
X
O
(iv)
(b)
N
N
N
N
+
Ph2P
Ph2P
+
Scheme 1. Reagents and conditions: (i) 1,2-dibromoethane (4.4 equiv.),
THF, r.t., 2 d (23%); (ii) HPPh2 (1.1 equiv.), t-BuOK (1.05 equiv.),
DMSO, r.t., 1 h (91%). (iii) Ph2P(@O)(CH2)2Br, 150–160 ꢁC, 4–5 d (83%);
(iv) HSiCl3, chlorobenzene, 120 ꢁC, 3 h (75%).
The coordination geometry is distorted tetrahedral. For
both structures, the X(2)–Ni–X(3) angle is significantly
X
(i)
(iii)
N
N
HO
+
N
N
Br
(i)
(ii)
X = Br 3a
X = BF4 3b
2
(ii)
N
N
N
N
HO
(iii)
+
2
3a
BF4
X
(iv)
Br
+
N
+
N
N
N
MsO
Ph2P
Br
N
+
N
N
N
+
Br
Ph2P
1b
4
5
1a
Scheme 2. Reagents and conditions: (i) 1-bromoethanol, toluene, 120 ꢁC,
18 h (90%); (ii) NaBF4, H2O/CH2Cl2, r.t., 3 d (96%); (iii) MsCl, NEt3,
CH2Cl2, 0 ꢁC, 3 h (88%); (iv) HPPh2, t-BuOK, DMSO, r.t., 1 h
(76%).HSiCl3, chlorobenzene, 120 ꢁC, 3 h (75%).
Scheme 3. Reagents and conditions: (i) 1-bromoethanol, toluene, 120 ꢁC,
18 h (90%); (ii) PBr3, CH2Cl2, 0 ꢁC, 15 h (78%); (iii) HPPh2, t-BuOK,
DMSO, r.t., 1 h (95%).

J. Wolf et al. / Journal of Organometallic Chemistry 691 (2006) 433–443
435
Fig. 1. An ORTEP view of compounds 1a (left) and 1b (right). Ellipsoids are drawn at the 50% probability level. For 1a, C–Hꢁ ꢁ ꢁBr bonding interaction is
shown as dashed line.
Table 1
ring, which is parallel to the X(2)–Ni–X(3) wedge plane, or
to the establishment of a hydrogen bonding interaction be-
˚
Selected bond distances (A) and angles (ꢁ) for compounds 1a and 1b
1a
1b
tween the C(1) hydrogen atom and the halogen atom X(3).
The latter is suggested by the slightly longer Ni–X(3) dis-
tance relative to Ni–X(1) and Ni–X(2) for both structures.
˚
(a) Distances (A)
P(1)–C(111)
P(1)–C(121)
P(1)–C(12)
N(1)–C(1)
N(1)–C(2)
N(1)–C(11)
N(2)–C(1)
N(2)–C(3)
N(2)–C(211)
C(2)–C(3)
1.825(4)
1.827(5)
1.857(4)
1.315(5)
1.389(5)
1.479(5)
1.337(5)
1.388(5)
1.448(5)
1.330(6)
1.505(6)
1.833(2)
1.832(2)
1.856(2)
1.331(2)
1.374(2)
1.477(2)
1.321(2)
1.378(2)
1.460(2)
1.340(3)
1.515(3)
˚
Indeed, the X(3)–H(1) distances are 2.678 A (X = Cl) and
˚
2.826 A (X = Br), which, although longer than in the free li-
gand 1a (vide supra), are shorter than the sum of the van der
Waals radii of H and X. This does not exclude, however, the
possibility of an intermolecular stacking interaction. It is
important to underline that the other crystallographically
characterized [NiX3L]ꢀ with X = Cl and Br show a much
smaller dispersion for the Ni–X distances and X–Ni–X
angles. In particular, these are symmetry imposed (C3) for
C(11)–C(12)
(b) Angles (ꢁ)
[NiCl3(PPh3)]ꢀ [Ni–Cl = 2.233(2) A; Cl–Ni–Cl = 114.61(6)]
˚
C(111)–P(1)–C(121)
C(111)–P(1)–C(12)
C(121)–P(1)–C(12)
C(1)–N(1)–C(2)
C(1)–N(1)–C(11)
C(2)–N(1)–C(11)
C(1)–N(2)–C(3)
C(1)–N(2)–C(211)
C(3)–N(2)–C(211)
N(1)–C(1)–N(2)
C(3)–C(2)–N(1)
C(2)–C(3)–N(2)
N(1)–C(11)–C(12)
C(11)–C(12)–P(1)
103.7(2)
101.46(19)
101.6(2)
109.0(3)
125.4(3)
125.0(4)
107.9(4)
124.1(3)
127.9(4)
108.6(4)
106.9(4)
107.6(4)
112.1(3)
113.5(3)
102.60(9)
99.20(10)
in the Et4N+ salt [35]. For the corresponding Cy3PH+ salt
˚
102.48(10)
108.31(17)
125.37(17)
126.26(16)
108.25(16)
124.79(16)
126.72(16)
108.89(17)
107.14(17)
107.40(18)
112.78(17)
110.15(15)
they are in the ranges Ni–Cl = 2.231–2.239 A; Cl–Ni–
Cl = 111.2–117.7ꢁ [36]. Crystallographically characterized
phosphine tribromide anions are Ph4As+[NiBr3(PPh3)]ꢀ
˚
[Ni–Br = 2.365–2.382 A; Br–Ni–Br = 110.6–116.8ꢁ] [37]
+
˚
and tBu3PH [NiBr3(PtBu3)] [Ni–Br = 2.368–2.391 A; Br–
Ni–Br = 107.3–110.3ꢁ] [38,39]. The Ni–P distances for 6
˚
and 7 [2.2811(11) and 2.2865(17) A, respectively], are sub-
stantially shorter than those found in the above mentioned
[NiX3L]ꢀ structures, a factor which may be related to the
presence of the hydrogen bonding and the lengthening of
the Ni–X(3) distance.
As expected for tetrahedral Ni(II) complexes, com-
pounds 6 and 7 are paramagnetic: no signal is observed
N
by 31P NMR, while the H NMR spectra show broad sig-
+
N
1
X
Ph2P
1
(i) or (ii)
nals between 30 and ꢀ22 ppm. A variable temperature H
N
N
Ph2P
Ni
+
NMR study in acetone-d6 shows a linear dependence of the
chemical shifts with 1/T (e.g., see Fig. 3 for compound 6),
which indicates Curie–Weiss behaviour for both com-
plexes. Therefore, the compounds are typical tetrahedral
complexes of Ni(II), for which a spin triplet ground state
is expected [40].
X
X
X
X = BF4, 1b
X = Br, 1a
X = Cl, 6
X = Br, 7
Scheme 4. Reagents and conditions: (i) NiCl2, NaCl, THF, 60 ꢁC, 18 h;
(ii) NiBr2(DME), THF, 75 ꢁC, 1 h.
Rather surprisingly, these complexes give relatively
1
wider [122.56(4)ꢁ and 123.29(4)ꢁ for X = Cl and Br, respec-
tively], than the other two X–Ni–X angles. This could be
attributed to the conformation adopted by the C(12) phenyl
sharp H NMR and 31P resonances in MeOD, indicating
diamagnetism. It would seem, therefore, that the methanol
solvent has replaced the phosphine ligand in the metal

436
J. Wolf et al. / Journal of Organometallic Chemistry 691 (2006) 433–443
Fig. 2. An ORTEP view of compounds 6 (left) and 7 (right). Ellipsoids are drawn at the 50% probability level. H atoms have been omitted for clarity.
Table 2
25
15
5
˚
Selected bond distances (A) and angles (ꢁ) for compounds 6 and 7
6
7
˚
(a) Distances (A)
-5
Ni(1)–X(1)
Ni(1)–X(2)
Ni(1)–X(3)
Ni(1)–P(1)
N(2)–C(1)
N(2)–C(3)
N(2)–C(12)
N(3)–C(1)
N(3)–C(4)
N(3)–C(311)
P(1)–C(121)
P(1)–C(111)
P(1)–C(11)
C(3)–C(4)
2.2644(11)
2.2197(11)
2.2959(11)
2.2811(11)
1.317(5)
1.382(4)
1.470(5)
1.339(5)
1.370(5)
1.446(5)
1.805(4)
1.817(4)
1.840(4)
1.346(5)
1.524(5)
2.3376(11)
2.3072(11)
2.3679(10)
2.2865(17)
1.310(7)
1.386(8)
1.485(7)
1.323(7)
1.391(8)
1.455(7)
1.807(6)
1.809(7)
1.839(6)
1.330(9)
1.527(8)
-15
-25
0.003 0.0035 0.004 0.0045 0.005
1/T(1/K)
Fig. 3. Temperature dependence of selected 1H NMR resonances of
complex 6.
obtained by dissolving complex 7 in MeOD. At lower tem-
peratures, the signal shifts downfield and becomes sharper
and more intense.
In an attempt to dihydrohalogenate complexes 6 and 7
and generate a neutral phosphine-functionalized N-hetero-
cyclic carbene complex of nickel(II), which would be re-
lated to the recently reported palladium(II) analogue [9],
the reaction of 6 and 7 with various base/solvent systems
was investigated. In a parallel fashion, we also investigated
the deprotonation of compound 1a under the same condi-
tions. We first settled our choice on strong bases like n-
BuLi, LiN(SiMe3)2 or KN(SiMe3)2. Compounds 1a, 6
and 7 are all insoluble in THF, but readily dissolve when
either one of these bases is added, to afford orange-brown
solutions. Our attempts to isolate a nickel complex from
these solutions, however, were not successful.
C(11)–C(12)
(b) Angles (ꢁ)
X(2)–Ni(1)–X(1)
X(2)–Ni(1)–P(1)
X(1)–Ni(1)–P(1)
X(2)–Ni(1)–X(3)
X(1)–Ni(1)–X(3)
P(1)–Ni(1)–X(3)
C(1)–N(2)–C(3)
C(1)–N(2)–C(12)
C(3)–N(2)–C(12)
C(1)–N(3)–C(4)
C(1)–N(3)–C(311)
C(4)–N(3)–C(311)
N(2)–C(1)–N(3)
C(4)–C(3)–N(2)
C(3)–C(4)–N(3)
C(12)–C(11)–P(1)
N(2)–C(12)–C(11)
110.34(4)
104.29(4)
101.68(4)
122.56(4)
109.96(4)
105.66(4)
109.1(3)
125.6(3)
124.9(3)
108.3(3)
127.0(3)
124.7(3)
108.4(3)
106.4(4)
107.7(4)
116.1(3)
112.5(3)
112.65(4)
103.80(5)
103.00(5)
123.29(4)
107.36(4)
104.45(5)
108.5(5)
125.1(5)
126.1(5)
108.1(5)
125.7(5)
126.0(5)
109.1(5)
107.3(6)
106.9(5)
116.0(4)
111.9(5)
The formation and stability of the putative carbenic spe-
cies was therefore probed by H, 13C and 31P NMR inves-
1
tigations of the reaction of 1a with KN(SiMe3)2 in THF-d8.
At ꢀ10 ꢁC, the 1H NMR spectrum clearly indicated the ab-
sence of the imidazolium proton between 10 and 11 ppm,
while the 31P NMR spectrum shows only one signal at
ꢀ22.2 ppm, and the 13C NMR spectrum shows a large up-
field shift of the carbon situated between the two nitrogen
atoms, from 141 to 215 ppm.
All these observations agree with the generation of a car-
benic species. No degradation of the ligand occurs under
these conditions. However, our attempts to crystallise the
free carbene were not successful, because decomposition
coordination sphere and that the signals observed are due
to the free ligand. Indeed, the observed H and 31P chemi-
1
cal shift(s) correspond to that of compound 1. This behav-
iour can be rationalized by the presence of a dynamic
coordination/dissociation process, inducing broadening
and shifting of the free ligand resonances as a result of
the complex paramagnetism. This hypothesis is confirmed
by a variable temperature 31P NMR study of solutions

J. Wolf et al. / Journal of Organometallic Chemistry 691 (2006) 433–443
437
occurred as shown by a colour change from colourless to
red at room temperature. This behaviour is quite different
from that of a similar ligand, bearing a (2,6-diisopro-
pyl)phenyl moiety instead of a mesityl, which could be crys-
tallized under the same conditions [41]. This results suggests
that the steric protection by the 2,6-isopropyl substituents
plays a key role in the stabilization of the N-heterocyclic
carbene at room temperature.
show that the replacement of the (2,6-diisopropyl)phenyl
substituent by a mesityl group, whose steric protection is
not much smaller, does not allow room temperature stabil-
ity. However, the formation of the carbene by deprotona-
tion of 1 below 0 ꢁC is indeed confirmed, thus it may be
intercepted by the nickel ion to form a stable coordination
compound.
In initial studies aimed at obtaining a nickel(II)–carbene
complex, ligand 1a was first deprotonated using Li(N-
SiMe3)2 or K(NSiMe3)2 in THF at ꢀ40 ꢁC and then added
to a nickel(II) precursor (NiBr2 or NiBr2(DME)). The disap-
pearance of the imidazolium proton could be observed by 1H
NMR monitoring. However, the resulting brown-orange
reaction mixture showed a complex 31P NMR spectrum
and we could not isolate and characterise the expected com-
plex (see Scheme 5). In subsequent studies, complexes 6 and 7
were deprotonated using similar conditions (Scheme 5). A
brown-orange mixture was again formed, but once again a
clean product could not be obtained.
1
The H and 31P NMR monitoring of the deprotonation
product of 1a in THF-d8 demonstrates its thermal instabil-
1
ity. The two imidazole ring proton signals in the H NMR
(located at 7.45 and 7.04 ppm at or below ꢀ10 ꢁC) notice-
ably shift upfield to 7.32 and 6.91 ppm, respectively, by the
time the temperature reaches 0 ꢁC (Fig. 4(a)). Simulta-
neously, the 31P NMR spectrum exhibits a sharp, predom-
inant signal at ꢀ21.75 ppm and a small, broad signal at ca.
ꢀ20.5 ppm (probably minor amounts of material that has
already decomposed) at ꢀ10 ꢁC or below (Fig. 4(b)).
However, when the temperature reached 0 ꢁC, only one
sharp signal at ꢀ20.55 ppm was left. Furthermore, no car-
benic carbon resonance at 215 ppm could be seen in the 13
C
2.3. Catalytic studies
NMR spectrum after leaving the sample for several days at
room temperature, under argon. These results indicate the
occurrence of an irreversible structural change that con-
sumes the carbene functionality at or above 0 ꢁC, consis-
tent with the colour change of the carbenic solution.
However, decomposition yields complex NMR spectra.
The only exploitable data is the absence of signal between
10 and 11 ppm in 1H NMR, that should correspond to the
imidazolium proton.
Nickel catalysts have been proved highly effective for
C–C coupling reactions between a Grignard reagent and
an aryl or alkyl halide (Kumada–Corriu reaction), usually
more so than their palladium analogues. Since the discov-
ery of the metal-catalysed reaction by Kumada and Corriu
One hypothesis is that the carbene compound dimerizes
to yield an alkene derivative, as was shown to occur for
analogous systems [42–44]. We have made no further efforts
to characterize the decomposition products. Danopoulos
et al. [41] isolated the {1-[b-(diphenylphosphino)ethyl]-3-
N
N
X
+
N
N
N
(i)
N
(ii) Ph P
2
Ph P
2
Ni
Br
Ni
X
X
X
X
PPh
6 or 7
2
1a
[(2,6-diisopropyl)phenyl]imidazol-2-ylidene}
compound
and suggested that the presence of bulky groups on both
nitrogen atoms of the heterocyclic ring is not necessary
for the isolation of stable carbenes. Our results, however,
Scheme 5. Reagents and conditions: (i) KN(SiMe3)2, THF, ꢀ40 ꢁC, then
NiBr2 or NiBr2(DME). (ii) n-BuLi, LiN(SiMe3)2 or KN(SiMe3)2, THF,
ꢀ40 ꢁC.
Fig. 4. NMR monitoring of the THF-d8 solution obtained from 1a and KN(SiMe3)2. (a) 1H NMR spectra. (b) 31P spectra.

438
J. Wolf et al. / Journal of Organometallic Chemistry 691 (2006) 433–443
in the early 1970s [45,46], many ligands have been reported,
especially (chelating) diphosphines [47–57], but very few
examples of metal-imidazolium salt systems have been re-
ported. Moreover, catalytic systems involving the reaction
of unactivated aryl chlorides with aryl Grignard reagents
have been described only recently [58,59]. Amongst them
is a very efficient Pd-imidazolium chloride precatalyst de-
scribed by Huang et al. [59], though this system required
the use of relatively elevated temperatures. The only known
examples involving nickel-N-heterocyclic carbene systems
are complexes A, reported by Bo¨hm et al. in [21].
and reductive elimination steps involved in the generally
accepted mechanism, by stabilising the metal centre at dif-
ferent stages of the catalytic cycle.
For the above reasons, we considered that the nickel
carbene-phosphine complex that is expected to form upon
dehydrohalogenation of 6 or 7 may exhibit an interesting
catalytic activity. Our inability to isolate this complex did
not prevent us from testing 6 and 7 themselves, since they
may be deprotonated to the neutral carbene complex
in situ by the Grignard reagent. A first test was thus carried
out with compound 7 for the reaction between phenylmag-
nesium chloride and iodobenzene in N,N-dimethylaceta-
mide (the precatalyst being soluble in this solvent). The
catalytic activity was poor (80% conversion, 8% yield of
biphenyl after 20 h at room temperature), even lower than
that of NiBr2 under identical conditions (100% conversion,
56% yield of biphenyl). Much more encouraging results
were obtained, on the other hand, for the Kumada cou-
pling of 4-chloroanisole with phenylmagnesium chloride
in THF (Scheme 6). The results are summarised in Table 3.
Pleasingly, when the reaction was carried out with a
3 mol% suspension of 6 in THF, without prior deprotona-
tion of the imidazolium moiety (Table 3, entry 3), a 100%
conversion and a 80% yield (relative to the limiting 4-chlo-
roanisole reagent) for the expected product 10 were ob-
tained. Under the same conditions, Bo¨hm et al. recovered
a non negligeable amount of 4-chloroanisole (entries 1
and 2) and obtained a lower proportion of 10.
Cl
Ar
Ar
Ar = 2,4,6-trimethylphenyl or
2,6-diisopropylphenyl
N
N
+
/ Ni(acac)2
A
These systems are able to couple aryl chlorides with aryl
Grignard reagents at room temperature and in very good
yields [21]. To date, no catalyst bearing a bifunctional li-
gand with a N-heterocyclic carbene has been tested in the
Kumada–Corriu reaction. However, it is known that a
proper choice of ligands can affect both oxidative addition
When a base was added to pre-catalyst 6 (entry 4), a
total conversion was again observed (only traces of 4-
chloroanisole could be detected), but with a lower propor-
tion of 10, and more biphenyl 12. This change in selectivity
does not seem to be related to the prior addition of a base
to the pre-catalyst, since similar results were obtained with
7 (entries 5 and 7), but with an inversion of the selectivity.
Slightly better yields, however, were obtained with 7 com-
pared to 6. In order to evaluate the activity of our com-
plexes, the catalyst ratio (7, entry 6) was lowered to
2 mol%. Again, the conversion after 18 h was complete,
and the distribution of products was quite similar to that
observed with 3 mol% catalyst. However, the amount of
homocoupling product 13 raised from 1% to 7%, and the
isolated yield was somewhat lower (68%). A small amount
Scheme 6.
Table 3
Nickel-catalysed (NiCl3L (6) and NiBr3L (7)) Kumada–Corriu reaction of 4-chloroanisole (1 equiv.) with phenylmagnesium chloride (1.5 equiv.) at room
temperature in THF (18 h)
Entry
Catalyst (mol%)
Base
Products (%) distribution (GC) 10/8/11/12/13/14
Isolated yield 10 (%)c
1a
2a
3b
4b
5b
6b
7b
a
IMes/Ni(acac)2
IPr/Ni(acac)2
NiCl3L 6 (3)
NiCl3L 6 (3)
NiBr3L 7 (3)
NiBr3L 7 (2)
NiBr3L 7 (3)
–
–
–
67/18/2/6/7/0
–
–
71/19/1/16/9/0
85/0/0.5/9.5/2/3
75/0.3/0.5/18/4/1.3
74/0/4/20/1/tr.
66/0/4/22/7/1
80
80
83
68
92
KN(SiMe3)2
–
–
n-BuLi
87/0/1/10/1.5/0.5
Ref. [21].
b
c
All reactions were repeated to ensure a good reproducibility of the results. Yields are not optimised.
Relative to 4-chloroanisole. The relatively large amount of biphenyl 12 originates from the excess Grignard reagent.

J. Wolf et al. / Journal of Organometallic Chemistry 691 (2006) 433–443
439
the deprotonation products of 6 and 7 and understand
their catalytic role; (iii) develop related systems by ligand
modification in order to improve the catalytic activity in
this and other C–C coupling reactions.
120
100
80
60
40
20
0
4. Experimental
All reactions were carried out under a dry argon atmo-
sphere using Schlenk glassware and vacuum line techniques.
Solvents for synthesis were dried and degassed by standard
methods before use. Elemental analyses were carried out by
the ‘‘Service dÕAnalyse du Laboratoire de Chimie de Coor-
0
100
200
Time (min)
300
1
dination’’ in Toulouse. H, 13C{1H, 31P}, 31P{1H} and 19F
Fig. 5. Percent conversion of 4-chloroanisole 8 (j) vs. time to give coupling
product 10 (r, GC yield). Conditions are as shown in Experimental
(method A).
NMR data were recorded on Bruker AM-250 and AV-
500 spectrometers for H, operating at 250 and 500 MHz,
1
respectively, on Bruker AV-500 for 13C and 31P, operating
at 125.8 and 202.5 Hz respectively, and on Bruker AC-200
for 19F, operating at 188 MHz. The spectra were referenced
internally using the signal from the residual protiosolvent
(1H) or the signals of the solvent (13C). Mass spectra (elec-
trospray ionisation or chemical ionisation) were obtained
from acetonitrile or methanol solutions on a Nermag
R10-10 instrument. GC chromatograms were recorded on
a Fisons 8000 Series GC equipped with a SPB-5 capillary
column and the products were identified by comparison
with authentic samples. Chromatographic work was per-
of terphenyl was observed as well, which did not occur with
IMes/Ni(acac)2 or IMes/Ni(acac)2 systems [60]. These re-
sults are equal or slightly superior to those reported by
Bo¨hm et al. for their bis-carbene nickel(II) catalytic system.
As we always observed a total conversion of the starting
material after 18 h, we decided to follow the conversion of
4-chloroanisole in time (typical reaction conditions of
Table 1, entry 5): aliquots of the reaction mixture were
quenched at regular intervals and analysed by gas chroma-
tography: we were pleased to see that the conversion was
almost total after only 1 h (96%, see Fig. 5), which suggests
that the catalytic species is very active for this system. In-
deed, 75% product is formed after only 30 min, and 81%
after 1 h. To the best of our knowledge, no analogous mon-
itoring experiments have been previously reported for this
reaction with use of related complexes as catalysts. It is
therefore impossible to make more precise comparisons
of catalytic activity. It seems, however, that this system is
much more active than previously appreciated and looks
very promising for future catalytic applications.[21] Fur-
ther studies in our laboratory will be devoted to further
optimizing it.
˚
formed on Silica gel 60A. Commercial chemicals were from
Acros, Aldrich and Avocado.
4.1. 1-(2-Hydroxyethyl)-3-(2,4,6-trimethylphenyl)-
imidazolium bromide (3a)
2-Bromoethanol (2.1 mL, 29.0 mmol) was added at
room temperature to a toluene solution (75 mL) of N-
(2,4,6-trimethylphenyl) imidazole (2) (4.92 g, 26.4 mmol).
The mixture was stirred at 120 ꢁC for 18 h. During this
time a white solid precipitated in the flask. The suspension
was cooled to room temperature, the solid was decanted off
and washed with toluene (2 · 15 mL). A white solid was
1
obtained. Yield: 7.4 g, 90%. H NMR (250 MHz,CDCl3):
d = 2.07 (s, 6H), 2.33 (s, 3H), 3.54 (br, 1H), 4.03 (t,
3. Conclusions
3
3J = 4.8 Hz, 2H), 4.85 (t, J = 4.9 Hz, 2H), 6.99 (s, 2H),
3
3
In summary, we have presented the synthesis and char-
acterisation of new nickel(II) complexes, where the metal is
bonded to a phosphine ligand that contains a pendant imi-
dazolium moiety. The deprotonation of the free ligand gen-
erates an unstable imidazolin-2-ylidene (observed at low
temperature by NMR). By comparison with the previously
reported N-2,6-diisopropylphenyl analogue, the N-mesityl
group is much poorer for sterically protecting the carbene
function. The deprotonation of the coordinated ligand
does not lead to isolable neutral carbene complexes. How-
ever, these precursors have shown promising results in
catalysis for the Kumada–Corriu coupling reaction, with
low catalyst loadings and good yields. We are now inter-
ested in: (i) studying more thoroughly the reactivity of
complexes 6 and 7 in catalysis; (ii) identify the nature of
7.16 (t, J = 1.5 Hz, 1H), 7.97 (t, J = 1.5 Hz, 1H), 9.64
(s, 1H) (data consistent with those found in the literature).
4.2. 1-(2-Hydroxyethyl)-3-(2,4,6-trimethylphenyl)-
imidazolium tetrafluoroborate (3b)
NaBF4 (7.05 g, 64.26 mmol) was added to a biphasic
solution (CH2Cl2/H2O: 1/2, 60 mL) of 3a (4.0 g,
12.85 mmol). The mixture was stirred for three days at room
temperature (10 mL). The two layers were separated, the
aqueous phase was extracted with CH2Cl2 (5 mL) and the
combined organic extracts washed with water (10 mL).
The solution was dried (MgSO4), filtered and concentrated
in vacuum to give a pale orange wax. Yield: 3.95 g (97%).
Mp 81–82 ꢁC. C14H19BF4N2O (318.12) Calcd: C, 52.86;

440
J. Wolf et al. / Journal of Organometallic Chemistry 691 (2006) 433–443
H, 6.02; N, 8.81%. Found: C, 52.82; H, 5.76; N, 8.63%. 1H
NMR (500 MHz, CDCl3): d = 2.03 (s, 6H), 2.34 (s, 3H),
3.06 (br, 1H), 3.96 (t, 3J = 4.8 Hz, 2H), 4.51 (t,
added to a DMSO solution (2 mL) of 5 (445 mg,
1.13 mmol). The solution was allowed to stir for 1 h at room
temperature. The solvent was then removed under vacuum.
Methanol (5 mL) was added to quench excess KPPh2, then
removed under vacuum. Dichloromethane (10 mL) was
added and the mixture was filtered. The filtrate was concen-
trated (ca. 1.5 mL) and diethyl ether (20 mL) was added.
The resulting precipitate was separated and the product
was obtained as a white air sensitive solid. Colorless crystals
were obtained by slow diffusion of diethyl ether into a
CH2Cl2 solution. Yield: 540 mg (95%). 1H NMR
(500 MHz, CDCl3): d = 2.08 (s, 6H), 2.36 (s, 3H), 2.93 (t,
3
3J = 4.8 Hz, 2H), 7.01 (s, 2H), 7.19 (t, J = 1.6 Hz, 1H),
7.78 (t, 3J = 1.6 Hz, 1H), 8.70 (t, 3J = 1.6 Hz, 1H); 13C
NMR (125.8 MHz, CDCl3): d = 17.15, 21.09, 52.37, 60.46,
123.28, 123.95, 129.77, 130.68, 134.46, 136.85, 141.24; 19F
NMR (188 MHz, CDCl3): d = ꢀ74.79. MS (IS), m/z (%):
232, (100) [M+ ꢀ BF4]; 87, (100) [Mꢀ ꢀ C14H19N2O].
4.3.1-(2-Bromoethyl)-3-(2,4,6-trimethylphenyl)-
imidazolium bromide (5)
3
3
3J = 6.9 Hz, 2H), 4.86 (dt, J = 11.9 Hz, J = 6.8 Hz, 2H),
3
PBr3 (0.19 mL, 2 mmol) was slowly added to a cold
CH2Cl2 solution (10 mL, 0 ꢁC) of 3a (622 mg, 2 mmol).
The mixture was stirred for 15 h at room temperature, di-
luted with CH2Cl2 (30 mL) and added to a cold saturated
NaHCO3 solution (20 mL, 0 ꢁC). The organic phase was ex-
tracted and washed with cold saturated NaHCO3 solution
(1 · 5 mL, 0 ꢁC). The solution was dried (MgSO4), filtered
and concentrated in vacuum. A white solid was obtained.
7.02 (s, 2H), 7.10 (t, J = 1.8 Hz, 1H), 7.36 (m, 6H), 7.46
3
3
(m, 4H), 7.66 (t, J = 1.7 Hz, 1H), 10.41 (t, J = 1.4 Hz,
1H); 31P NMR (202.5 MHz, CDCl3): d = ꢀ23.29 (s) (data
consistent with those found in the literature).
4.6.1-(2-Diphenylphosphinoethyl)-3-(2,4,6-trimethyl-
phenyl)imidazolium tetrafluoroborate (NCNþBF 4ꢀ) (1b)
1
Yield: 580 mg (78%). H NMR (250 MHz, CDCl3): d =
Method A: KPPh2, freshly made from t-BuOK (460 mg,
4.1 mmol) and HPPh2 (0.75 mL, 4.3 mmol) in DMSO
(5 mL), was added to a DMSO solution (3 mL) of 4
(1.55 g, 3.9 mmol). The solution was allowed to stir for
1 h at room temperature. The solvent was then removed
under vacuum. Methanol (15 mL) was added to quench ex-
cess KPPh2, then removed under vacuum. CH2Cl2 (10 mL)
was added and the mixture was filtered. The filtrate was
concentrated (ca. 3 mL) and diethyl ether (40 mL) was
added. The resulting precipitate was separated and the
product was obtained as a white air sensitive solid. Yield:
1.42 g (75%).1H NMR (250 MHz, CDCl3): d = 2.03 (s,
3
2.07 (s, 6H), 2.33 (s, 3H), 4.03 (t, J = 5.5 Hz, 2H), 5.23
(t, 3J = 5.4 Hz, 2H), 7.00 (s, 2H), 7.17 (t, 3J = 1.7 Hz,
3
3
1H), 8.31 (t, J = 1.7 Hz, 1H), 10.09 (t, J = 1.7 Hz, 1H)
(data consistent with those found in the literature).
4.4.1-(2-Ethylmesylate)-3-(2,4,6-trimethylphenyl)-
imidazolium tetrafluoroborate (4)
NEt3 (1 mL, 6.84 mmol) was added to a cold CH2Cl2
solution (0 ꢁC, 20 mL) of 3b (1.45 g, 4.56 mmol). The mix-
ture was stirred at 0 ꢁC for 15 min, then CH3SO2Cl
(0.53 mL, 6.84 mmol) was slowly added. The temperature
was allowed to reach slowly 25 ꢁC over 3 h and the mixture
was concentrated (ca. 5 mL). Water (10 mL) was added
and the mixture was stirred for 12 h. The two layers were
separated, the aqueous phase was extracted with CH2Cl2
(5 mL) and the combined organic extracts washed with
water (5 mL). The solution was dried (MgSO4), filtered
and concentrated in vacuum to give a brown wax. Yield:
1.6 g (89%). Mp 42–44 ꢁC. C15H21BF4N2O3S (396.21)
Calcd: C, 45.47; H, 5.34; N, 7.07%. Found: C, 45.36; H,
3
3
6H), 2.33 (s, 3H), 2.80 (t, J = 6.9 Hz, 2H), 4.64 (t, J =
6.9 Hz, 2H), 6.99 (s, 2H), 7.10 (s, 1H), 7.35 (m, 6H), 7.46
(m, 4H), 7.57 (s, 1H), 9.34 (s, 1H). 19F NMR (188 MHz,
CDCl3): d = ꢀ74.70 (s); 31P NMR (101 MHz, CDCl3):
d = ꢀ20.08 (s).1H NMR revealed a mixture of anions
ðMeSOꢀ3 [d 2.61, s]/BFꢀ4 Þ.
Method B: NaBF4 (530 mg, 4.75 mmol) was added to a
biphasic solution (CH2Cl2/H2O, 1/3, 12 mL) of 1a (460 mg,
0.95 mmol). The mixture was stirred for 24 h at room tem-
perature then the two layers were separated, the aqueous
phase was extracted with CH2Cl2 (5 mL) and the combined
organic extracts washed with water (2 mL). The solution
was dried (MgSO4),filtered and concentrated (2 mL).
Et2O (20 mL) was added to give a white precipitate, it
was separated and dried in vacuum. Colorless, air sensitive
crystals were obtained by slow diffusion of diethyl ether
into a CH2Cl2 solution. Yield: 410 mg (88%). Mp 109–
110 ꢁC. C26H28BF4N2P (486.3). Calcd: C, 64.22; H, 5.80;
1
4.95; N, 6.84%. H NMR (500 MHz, CDCl3): d = 2.06 (s,
3
6H), 2.35 (s, 3H), 3.07 (s, 3H), 4.71 (t, J = 4.3 Hz, 2H),
3
4.82 (t, J = 4.3 Hz, 2H), 7.02 (s, 2H), 7.22 (s, 1H), 7.85
(s, 1H), 8.73 (s, 1H);13C NMR (125.8 MHz, CDCl3):
d = 17.18, 21.12, 37.34, 49.45, 68.09, 123.63, 124.17,
129.80, 130.56, 134.56, 137.23, 141.35; 19F NMR
(188 MHz, CDCl3): d = ꢀ74.22. MS (IS), m/z (%): 309.6,
(100) [M+ ꢀ BF4]; 87, (100) [Mꢀ ꢀ C15H21N2O3S].
1
N, 5.76%. Found: C, 63.73; H, 6.28; N, 5.29%. H NMR
4.5.1-(2-Diphenylphosphinoethyl)-3-(2,4,6-trimethyl-
phenyl)imidazolium bromide (NCN+Brꢀ) (1a)
(500 MHz, CDCl3): d = 2.03 (s, 6H), 2.35 (s, 3H), 2.77 (t,
3J = 7.1 Hz, 2H), 4.55 (dt, 3J = 10.7, 3J = 7.2 Hz, 2H),
3
7.01 (s, 2H), 7.15 (t, J = 1.8 Hz, 1H), 7.36 (m, 6H), 7.44
KPPh2, freshly made from t-BuOK (140 mg, 1.24 mmol)
and HPPh2 (0.24 mL, 1.30 mmol) in DMSO (2 mL), was
(m, 4H), 7.61 (t, 3J = 1.8 Hz, 1H), 8.82 (t,3J = 1.8 Hz,
1H); 13C NMR (125.8 MHz, CDCl3): d = 17.31, 21.13,

J. Wolf et al. / Journal of Organometallic Chemistry 691 (2006) 433–443
441
29.11, 48.09, 123.43, 123.44, 128.98, 129.44, 129.79, 130.56,
132.77, 134.44, 136.82, 141.37; 19F NMR (188 MHz,
CDCl3): d = ꢀ74.69 (s); 31P NMR (202.5 MHz, CDCl3):
d = ꢀ23.52 (s). MS (IS), m/z (%): 399.6, (100)
[M+ ꢀ BF4]; 87, (100) [Mꢀ ꢀ C26H28N2P].
(500 MHz, d6-(Me)2CO): d = ꢀ2.13 (br), 0.47 (br), 1.30
(s), 1.42 (br), 1.90 (s), 2.07 (br + acetone), 2.12 (s), 2.90
(br), 3.76 (s), 4.07 (br), 6.16 (s), 6.33 (s), 6.57 (br), 20.80
(br). MS (IS), m/z (%): 399, (100) [M+ ꢀ NiBr3]; 79–81,
(100) [Mꢀ ꢀ C26H28N2PNiBr2]. MS (DCI[NH3]), m/z (%):
535, (82) [(M + NH3)+ ꢀ Br].
4.7. [NiCl3]ꢀ(NCN+) (6)
4.9. Typical procedures for Kumada–Corriu reactions
NiCl2 (18 mg, 0.14 mmol) was added to a THF suspen-
sion (3 mL) of 1b (49 mg, 0.1 mmol) [synthesised by method
B]. The mixture was stirred for 18 h at 60 ꢁC to give a red/
violet suspension. After filtration, a blue solid was obtained
and washed with CHCl3 (3 · 2 mL), dissolved in acetoni-
trile (2 mL), filtered and acetonitrile was removed in vac-
uum to give a blue solid. NaCl (30 mg, 0.5 mmol) was
added to the violet solution. The mixture was stirred at
60 ꢁC for 1 h. A blue precipitate appeared and the solution
became colorless. The suspension was filtered and washed
with THF (2 · 5 mL). The product was dissolved in aceto-
nitrile, filtered and dried in vacuo to give a blue solid. Glo-
bal yield: 35 mg (63%). Blue crystals were obtained by slow
diffusion of diethyl ether into an acetonitrile solution. Mp
231–233 ꢁC. C26H28Cl3N2NiP (564.55) Calcd: C, 55.32; H,
Method A: 4-Chloroanisole (0.12 mL, 1.0 mmol) was
added to a suspension of 7 (21 mg, 0.03 mmol) in 1 mL
THF. Phenylmagnesium chloride (0.75 mL, 1.5 mmol)
was then added dropwise, and the reaction mixture was
stirred for 18 h at room temperature. H2O was added,
the solution was dried (MgSO4), filtered on a short path
of silica gel and rinsed with dichloromethane. The crude
mixture was analysed by gas chromatography, and then
purified by column chromatography on silica gel (eluent:
pentane/dichloromethane 95:5) to give 10 as a white solid
(NMR data consistent with those found in the literature).
Yield: 153 mg (83%).
Method B: n-BuLi (22 lL, 0.036 mmol) was added to a
suspension of 7 (21 mg, 0.03 mmol) in 1 mL THF, which
dissolved instantaneously to give a brown solution. 4-Chlo-
roanisole (0.12 mL, 1.0 mmol) was added to the solution
1
5.00; N, 4.96%. Found: C, 55.00; H, 4.99; N, 4.57%. H
NMR (500 MHz, d3-MeOD): d = 1.94 (s, 6H), 2.23 (s,
3
3
3H), 2.71 (t, J = 5.9 Hz, 2H), 4.35 (t, J = 5.8 Hz, 2H),
6.99 (s, 2H), 7.26 (m, 6H), 7.35 (m, 4H), 7.59 (t, 3J =
Table 4
Crystal data and structure refinement, compounds 1a and 1b
1.3 Hz, 1H), 7.84 (t, J = 1.3 Hz, 1H), 9.14 (s, 1H); 31P
3
NMR (202.5 MHz, d3-MeOD): d = ꢀ23.25 (br);13C NMR
(125.8 MHz, d3-MeOD): d = 15.94, 19.62, 28.27, 47–48,
123.06, 124.20, 128.47, 128.97, 129.19, 130.95, 132.43,
Identification code
Empirical formula
1b
1a
(C26H28N2P)(BF4) (C27H30Cl2N2P)Br,
CH2Cl2
1
Formula weight
Temperature (K)
Wavelength (A)
486.28
180(2)
0.71073
Triclinic
564.31
180(2)
134.33, 136.42, 141.06. H NMR (500 MHz, d6-(Me)2CO):
d = ꢀ2.13 (br), 0.47 (br), 1.30 (s), 1.42 (br), 1.90 (s), 2.07
(br + acetone), 2.12 (s), 2.90 (br), 3.76 (s), 4.07 (br), 6.16
(s), 6.33 (s), 6.57 (br), 20.80 (br). MS (IS), m/z (%): 399,
(100) [M+ ꢀ NiCl3]; 35, (100) [Mꢀ ꢀ C26H28N2PNiCl2].
MS (DCI[NH3]), m/z (%): 544, (3) [(M + NH3)+ ꢀ Cl].
˚
0.71073
Monoclinic
P21/c
14.352(2)
10.7141(18)
17.644(2)
Crystal system
Space group
ꢀ
P1
˚
a (A)
9.3799(12)
10.8049(14)
14.090(2)
71.863(13).
70.702(13)
74.799(11)
1260.5(3)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
4.8. [NiBr3]ꢀ(NCN+) (7)
90.289(10)
3
˚
Volume (A )
2713.1(7)
4
1.382
1.789
1160
NiBr2(DME) (309 mg, 1.00 mmol) was added to a sus-
pension of 1a (400 mg, 0.83 mmol) in THF (5 mL). The
mixture was stirred at 75 ꢁC for 1 h. The precipitate was fil-
tered, the green solid obtained was washed with THF
(2 · 5 mL) and CHCl3 (2 · 10 mL). The product was dis-
solved in acetone (20 mL), filtered on silica and was crystal-
lised from acetone to give green crystals. Yield: 555 mg
(95%). Mp 231–233 ꢁC. C26H28Br3N2NiP (697.9) Calcd:
C, 44.75; H, 4.04; N, 4.01%. Found: C, 43.59; H, 4.06;
Z
Dcalc (Mg/m3)
Absorption coefficient (mmꢀ1
F(000)
1.281
0.155
508
)
Crystal size (mm3)
h Range (ꢁ)
0.51 · 0.14 · 0.137 0.61 · 0.55 · 0.056
2.80–26.37
2.84–26.37
Reflections collected
9909
18657
Independent reflections (Rint
Completeness (%)
)
5159 (0.0323)
99.7
5539 (0.0734)
99.8
Absorption correction
Max. and min. transmission
Refinement method
None
Multi-scan
0.4461 and 0.2067
F2
1
N, 3.52%. H NMR (500 MHz, d3-MeOD): d = 2.01 (s,
F2
6H), 2.30 (s, 3H), 2.78 (t, 3J = 6.0 Hz, 2H), 4.40 (t,
3J = 5.9 Hz, 2H), 7.06 (s, 2H), 7.32 (m, 6H), 7.43 (m,
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
5159/0/310
0.890
R1 = 0.0444,
wR2 = 0.0953
R1 = 0.0833,
wR2 = 0.1073
5539/0/301
0.906
R1 = 0.0570,
wR2 = 0.1423
R = 0.0935,
wR2 = 0.1685
3
3
4H), 7.66 (d, J = 1.3 Hz, 1H), 7.92 (d, J = 1.3 Hz, 1H),
9.17 (s, 1H); 31P NMR (202.5 MHz, d3-MeOD): d =
ꢀ23.36 (br).13C NMR (125.8 MHz, d3-MeOD): d = 16.05,
19.70, 28.27, 47–48, 123.12, 124.22, 128.53, 129.03,
R indices (all data)
ꢀ3
˚
1
Residual density (e A
)
0.248 and ꢀ0.215 1.530 and ꢀ1.061
129.26, 131.02, 132.46, 134.42, 136.47, 141.11. NMR H

442
J. Wolf et al. / Journal of Organometallic Chemistry 691 (2006) 433–443
and after stirring for 5 min at room temperature, phenyl-
magnesium chloride (0.75 mL, 1.5 mmol) was added drop-
wise. The reaction mixture was stirred for 18 h at room
temperature. H2O was added, the solution was dried
(MgSO4), filtered on a short path of silica gel and rinsed
with dichloromethane. The crude mixture was analysed
by gas chromatography, and then purified by column chro-
matography on silica gel (eluent: pentane/dichloromethane
95:5) to give 10 as a white solid. Yield: 170 mg (92%)
(NMR data consistent with those found in the literature).
tion no. CCDC 277961–277964. Copies of the data can
be obtained free of charge on application to the Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax:
+44 1223 336 033; deposit@ccdc.cam.ac.uk).
Acknowledgements
We are grateful to the CNRS for support of this work
´
and the ‘‘Fonds Social Europeen’’ for a Ph.D. fellowship
to J.W.
4.10. X-ray structure determinations
References
Single crystal of each compound was mounted under in-
ert perfluoropolyether at the tip of glass fibre and cooled in
the cryostream of the Oxford-Diffraction XCALIBUR
CCD diffractometer. Data were collected using the mono-
chromatic Mo Ka radiation (k = 0.71073). The structures
were solved by direct methods (SIR97 [61]) and refined by
least-squares procedures on F2 using SHELXL-97 [62]. All
H atoms attached to carbon were introduced in calculation
in idealised positions and treated as riding models. The
drawing of the molecules was realised with the help of OR-
TEP32 [63]. Crystal data and refinement parameters are
shown in Tables 4 and 5. Crystallographic data (excluding
structure factors) have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publica-
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Table 5
Crystal data and structure refinement, compounds 6 and 7
Identification code
Empirical formula
6
7
C27H31Cl3N2Ni P, C26H28Br3N2 Ni P
1/2(C3H6O)
Formula weight
Temperature (K)
Wavelength (A)
593.57
180(2)
697.91
180(2)
˚
0.70930
Monoclinic
P21/n
12.1663(11)
9.1747(8)
26.402(2)
102.537(7)
2876.7(4)
4
0.71073
Monoclinic
P21/c
9.2547(7)
13.0627(10)
23.2366(17)
94.230(6)
2801.5(4)
4
Crystal system
Space group
˚
a (A)
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
Volume (A )
Z
Dcalc (Mg/m3)
Absorption coefficient (mmꢀ1
F(000)
1.371
1.030
1232
1.655
5.045
1384
)
Crystal size (mm3)
0.32 · 0.21 · 0.073 0.25 · 0.2 · 0.18
h Range ꢁ
Reflections collected
3.01–26.31
18520
2.89–26.37
20049
Independent reflections (Rint
Completeness (%)
)
5867 (0.0523)
99.8
5730 (0.0490)
99.8
Absorption correction
Max. and min. transmission
Refinement method
Analytical
0.9303 and 0.7776 0.5762 and 0.4246
F2
Analytical
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