Facile synthesis of [(NHC)(NHCewg)RuCl2(CHPh)] complexes

Article abstract of DOI:10.1016/j.jorganchem.2010.07.014

The utility of [(NHC)(PPh₃)RuCl₂(CHPh)] for the facile and efficient synthesis of ten complexes of the type [(NHC)(NHC _ewg)RuCl₂(CHR)] with saturated and unsaturated NHC ligands in 85-94% isolated yield via a simple one step synthesis utilizing [AgI(NHC_ewg)] as NHC_ewg transfer reagents was demonstrated.

Full text of DOI:10.1016/j.jorganchem.2010.07.014

Journal of Organometallic Chemistry 695 (2010) 2418e2422
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Facile synthesis of [(NHC)(NHCewg)RuCl2(CHPh)] complexes
*
Stefanie Wolf, Herbert Plenio
Organometallic Chemistry, FB Chemie, Petersenstr. 18, Technische Universität Darmstadt, 64287 Darmstadt, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
The utility of [(NHC)(PPh3)RuCl2(CHPh)] for the facile and efficient synthesis of ten complexes of the type
[(NHC)(NHCewg)RuCl2(CHR)] with saturated and unsaturated NHC ligands in 85e94% isolated yield via
a simple one step synthesis utilizing [AgI(NHCewg)] as NHCewg transfer reagents was demonstrated.
Ó 2010 Elsevier B.V. All rights reserved.
Received 30 April 2010
Received in revised form
12 July 2010
Accepted 15 July 2010
Available online 23 July 2010
Keywords:
N-Heterocyclic carbene
Ruthenium
Olefin metathesis
Cyclic voltammetry
1. Introduction
relatively unstable [(NHC)RuCl2(CHPh)(py)2], for whose synthesis
a number of additional steps are needed [14]. One approach (of
N-Heterocyclic carbenes substituted with electron withdrawing
groups (NHCewg) display donor properties comparable to those of
trialkylphosphines [1e7]. Consequently, there was the chance that
the substitution of a PCy3 ligand in Grubbs 2nd generation
complexes by an NHCewg ligand would lead to precatalysts of
comparable performance in olefin metathesis [8]. This behavior
would be in contrast to that of symmetrical [(NHC)2RuCl2(CHR)]
type complexes, which were found to display only modest catalytic
activity in such reactions [9e11]. Nonetheless, we recently
several others) [15e17] leading to such complexes is displayed in
Scheme 2 [18].
More recently, the much more stable pyridine complex [(NHC)
RuCl2(3-phenylindenylid-1-ene)(py)] [19] was used to prepare
a number of new complexes (Scheme 1) [20]. The high stability and
the commercial availability of [(NHC)RuCl2(3-phenylindenylid-1-
ene)(py)]renderthis complex useful. Nonetheless, the synthesisof 1,
2 and 3 from simple ruthenium precursors requires some effort and
is not entirely satisfactory with respect to the number of synthetic
steps and especiallyconcerning the use of PCy3. This ligand is used to
replace PPh3 in [(PPh3)2RuCl2(CHPh)] to obtain the much more
stable [(PCy3)2RuCl2(CHPh)]. However, PCy3 does not occur in the
final products 1, 2 or 3. In the course of the synthesis one PCy3 is
replaced by an NHC ligand to furnish [(NHC)(PCy3)RuCl2(CHPh)]. In
the next step the second PCy3 is replaced by pyridine to afford
[(NHC)RuCl2(CHPh)(py)2] and next this pyridine is replaced by an
NHCewg. Obviously, this is not an ideal synthetic strategy.
demonstrated the excellent activity of [(NHC)(NHCewg
)
RuCl2(CHPh)] complex 1 in RCM reactions leading to tetrasub-
stituted olefins [12], even though this complex initiates much more
slowly than Grubbs 2nd generation complexes. Complex 1, being
the first member of this class, was available only in modest yield
(49%) via the reaction of [(NHC)RuCl2(CHPh)(py)2] with an in-situ
generated N-heterocyclic carbene (Scheme 1) [12].
This motivated us to improve and generalize the synthetic
access to such compounds (Scheme 1). It was found that the use of
[AgI(NHCewg)] complexes as NHC transfer reagents allows the
nearly quantitative conversion of [(NHC)RuCl2(CHPh)(py2)] into the
desired complexes 2 (Scheme 1) [13]. This improved synthesis
paved the way for the systematic variation of the NHCewg ligand
and the optimization of the catalytic activity, which finally led to
a series of new precatalysts with significantly improved activity in
RCM reactions [13]. Nonetheless, this approach still relies on the
Consequently, we wish to report here on a new and facilitated
synthesis of such complexes, which is shorter and more efficient
and does not rely on PCy3 containing intermediates.
2. Results and discussion
2.1. Synthesis of ruthenium complexes
Complexes [(NHC)(PPh3)RuCl2(CHPh)] are known and are
directly available from [(PPh3)2RuCl2(CHPh)] and NHC ligands
* Corresponding author.
E-mail address: plenio@tu-darmstadt.de (H. Plenio).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.07.014

S. Wolf, H. Plenio / Journal of Organometallic Chemistry 695 (2010) 2418e2422
2419
NHC
NHC
NHC
Cl
Cl
Cl
Ph
Ru
py Ru
py Ru
Cl
Cl
Ph
Cl
Ph
py
py
py
49%
AgI(NHCewg) >90%
AgI(NHCewg) >90%
NHCewg
N
N
N
N
N
N
Cl
Cl
Cl
Ph
Ru
Ru
Ru
Ph
Ph
R1
Cl
Cl
Cl
NO2
NO2
O2N
O2N
R2
N
N
R2
N
N
R1
N
N
R3
R4
R3
R4
1
2
3
Scheme 1. Synthesis of [(NHC)(NHCewg)RuCl2(CHR)] complexes, see Scheme 3 for the nature of R groups.
(Scheme 3). Complex 4 was first reported by Grubbs et al. and
prepared in the reaction of [(NHC)RuCl2(CHPh)(py)2]with PPh3 [14].
Later the synthesis of this complex was facilitated, when Ren He
et al. described its preparation from [(PPh3)2RuCl2(CHPh)] and NHC
[21,22]. Nolan first reported the closely related complex 5 [23], the
unsaturated relative of 4. We tested the reactions of 4 and 5 with
[AgI(NHCewg)] which led to the clean and quantitative conversion
into the respective new [(NHC)(NHCewg)RuCl2(CHR)] complexes 6
and the previously reported complexes 2. The products were
obtained in 89e94% isolated yield for 2 and in 85e94% isolated
yield for 6. With the exception of the complex 6e with R3, R4 ¼ H all
compounds are very stable and the microcrystalline material can be
stored under ambient atmosphere. In solution the complexes are
stable for a short time, but some decomposition can be observed
after a few hours of exposure to air. Nonetheless, the synthesis
reported here provides facile access to the previously reported
complexes 2aed and the new complexes 6aef in excellent yields
without the need for PCy3 or PCy3 containing intermediates.
The complexes with two different alkyl groups at the nitrogen of
the NHCewg (6b, d, f) occur as two different rotamers in a ratio of ca.
2: 1. Considering the significantly different bulk of the methyl and
the isopropyl group this was unexpected, but was observed before
for related complexes 2.
testing the performance of the newly synthesized complexes 6aef
with an unsaturated NHC backbone in six different RCM reactions
(Table 1). There is no clear “best” precatalyst, but the performance
of 6e is better than that of the other complexes, while the cyano
substituted 6c clearly is the least efficient in this series. The modest
performance of 6c is in line with our previous results. Despite the
fact that the cyano substituted NHCewg ligand is the least efficient
donor (see Table 2), it also tends to be a poor leaving group
compared to other NHCewg ligands. It seems that the cyano
substituted NHCewg is more strongly bound to ruthenium than
other NHCewg ligands e possibly the weaker
this NHCewg is overcompensated by its strong
s
p
-donor capacity of
-accepting ability
[27]. For a better evaluation of the screening data, the yields from
the best performers from two previous studies are also listed in
Table 1. For the reactions tested here, complex 2a with a saturated
NHC backbone is slightly better than 6e, which has an unsaturated
NHC ligand. However, the performance of 1 and 6e are comparable.
N
N
N
N
Cl
Cl
Ru
Ru
4
5
Cl
Ph
Cl
Ph
2.2. Catalytic activity in ring closing metathesis reactions
PPh3
)
PPh3
)
Complexes 1 and 2a (and other related complexes) were shown
to display excellent activities in RCM reactions leading to tri- and
tetrasubstituted olefins [13], which were previously considered to
be difficult RCM reactions [24e26]. We were therefore interested in
AgI(NHCewg
N
AgI(NHCewg
N
N
N
Cl
Cl
Ru
Ru
PCy3
PPh3
Cl
Ph
R1
Cl
Ph
R1
Cl
Cl
PCy3
NHC
Ph
R2
N
N
R2
N
N
Ru
Ru
Cl
Cl
Ph
R3
R4
R3
R4
PCy3
PPh3
1
2
3
4
2
6
or R ,R ; R ,R ; yield
6a
iPr,iPr; Cl,Cl; 91%
iPr,Me; Cl,Cl; 93%
NHC
6b
NHC
Cl
NHC
Cl
6c Me,Me; CN,CN; 94%
2a iPr,Me; Cl,Cl; 94%
Cl
AgI(NHC)
>90%
py
6d
iPr,Me; H,NO2; 90%
2b
Ru
Ru
Et,Et; Cl,Cl; 92%
Me,Me; H,H; 89%
iPr,Me; H,NO2; 90%
py Ru
Cl
6e Me,Me; H,H; 85%
2c
Cl
Ph
Cl
Ph
Ph
6f
iPr,Me; H,H; 88%
NHCewg
2d
PCy3
py
Scheme 2. Synthesis of [(NHC)(NHCewg)RuCl2(CHPh)] complexes.
Scheme 3. Facile synthesis of [(NHC)(NHCewg)RuCl2(CHPh)] complexes.

2420
S. Wolf, H. Plenio / Journal of Organometallic Chemistry 695 (2010) 2418e2422
Table 1
than those with saturated NHC [1], and that the effect of two
methyl groups (compared to two hydrogen substituents) amounts
to a ca. 30 mV cathodic shift [30]. It is therefore not surprising that
the redox potentials of complexes 6 and 2 are very similar (Table 2).
Yields (%) for RCM reactions leading to the depicted products using [Ru] complexes
6aef and comparative data using complexes 2a and 1.
0.5 mol% [Ru]
toluene, 80 o
C
3. Summary and conclusions
Product
6a
6b
6c
6d
6e
6f
2a
1
The simple, efficient and high-yielding synthesis of [(NHC)
(NHCewg)RuCl2(CHPh)] complexes with saturated and unsaturated
NHC ligands via [(NHC)(PPh3)RuCl2(CHPh)] and [AgI(NHCewg)] was
reported. The new synthetic route to such complexes requires
fewer synthetic steps than before, avoids the use of PCy3 and
Ts
N
88
97
e
62
93
77
99
98
CO2Et
CO2Et
affords excellent yields of the respective [(NHC)(NHCewg
)
RuCl2(CHPh)] complexes. The new [(NHC)(NHCewg)RuCl2(CHPh)]
complexes containing ligands with unsaturated backbones were
obtained and tested in demanding RCM reactions and found to be
only slightly less efficient in such transformations than optimized
complexes with saturated NHC ligands.
30
86
74
35
99
92
2
44
83
e
47
99
90
37
84
99
95
48
99
60
CO2Et
CO2Et
e
e
4. Experimental section
CO2Et
CO2Et
All chemicals were purchased as reagent grade from commercial
suppliers and used without further purification unless otherwise
noted. Solvents were dried by passing over Al2O3 and/or by storing
over molecular sieves unless otherwise noted. Pyridine was
degassed by freeze-pump-thaw cycles technique. Flash column and
preparative thin layer chromatography were performed using silica
gel 60 (0.063e0.20 mesh ASTM). TLC was performed by using Fluka
silica gel 60 F254 (0.2 mm) on alumina plates. NMR spectra were
recorded on Bruker DRX500 at 500 MHz (1H) and 126 MHz (13C),
respectively or on Bruker DRX300 at 300 MHz (1H), 75 MHz (13C),
93
e
O
O
17
88
e
1
17
70
23
91
<1
e
26
98
O
121 MHz (31P). The chemical shifts (
d) are given in ppm relative to
TMS. MS spectra were recorded on a Finnigan MAT95 spectrometer.
GC experiments were run on a Clarus 500 GC with autosampler and
52
51
58
95
FID detector. Column: Varian CP-Sil
8
CB (l
¼
15 m,
Screening conditions: reaction time: 24 h, substrate conversion determined by GC,
other reaction conditions as reported in ref. [20].
diam. ¼ 0.25 mm, dF ¼ 1.0 m), N2 (flow: 17 cm/s; split 1:50);
m
Injector-temperature: 200 ꢀC, detector temperature: 270 ꢀC.
Temperature program: isotherm 60 ꢀC for 5 min, heating to 300 ꢀC
with 25 ꢀC/min, isotherm for 5 min. The identity of all GC product
peaks was established by GC/MS on Finnigan MAT GCeMS. The
spectroscopic data (1H NMR) of the isolated products are identical
to those reported in the literature. Cyclic voltammetry: EG&G 263A-
2 potentiostat. Cyclic voltammograms were recorded in dry CH2Cl2
under an argon atmosphere at ambient temperature. A three-
electrode configuration was employed. The working electrode was
a Pt disk (diameter 1 mm) sealed in soft glass with a Pt wire as
counter electrode. The pseudo reference electrode was an Ag wire.
Potentials were calibrated internally against the formal potential of
octamethylferrocene (ꢁ0.010 mV (CH2Cl2) vs. Ag/AgCl). NBu4PF6
(0.1 mol/L) was used as supporting electrolyte.
2.3. Cyclic voltammetry
All of the newly synthesized complexes are characterized by
a reversible electrochemistry and consequently the redox poten-
tials for the new complexes 6aef were determined (Table 2). Those
redox potentials reflect the different electron donation of the
substituents at the NHCewg ligands [28,29]. The cyano substituted
complex 6c has by far the most anodic redox potential
(E ¼ 0.727 V), while the redox potential of 6f with two N-isopropyl
groups and hydrogen substituents (E ¼ 0.474 V) the least anodic.
Complexes 6aef are characterized by the absence of two methyl
groups para to the nitrogen atoms and consequently their redox
potentials are slightly different from that of complexes 2[13].
Therefore the comparison of the redox potentials is less straight-
forward. We observed before that the redox potentials with
unsaturated heterocycles are only slightly (20e30 mV) more anodic
[(NHC)(PPh3)RuCl2(CHPh)] 5: A dry Schlenk flask was charged
with imidazolium chloride (200 mg, 0.637 mmol), potassium t-
amylate (toluene 1.7 M, 375 ml, 0.637 mmol) and toluene (50 mL)
under an Ar atmosphere. The solution was stirred at room
temperature for 15 min. To this mixture was added
[(PPh3)2RuCl2(CHPh)] (500 mg, 0.637 mmol). The reaction mixture
was stirred for 1 h at room temperature, then the solvent was
completely removed under vacuum. The residue was washed with
pentane (3 ꢂ 25 ml) and filtered, and the resulting orange-brown
solid was dried under vacuum. Yield: 410 mg, 80%.
Table 2
Redox potentials of complexes 6aef and the closely related (i.e. same substituent at
the NHCewg ligand) complexes 2 (taken from Ref. [5]) with saturated NHC ligand.
E/V (Ea ꢁ Ec)/(mv)
E/V
6a
6b
6c
6d
6e
6f
0.538 (74)
0.573 (78)
0.727 (75)
0.627 (68)
0.492 (64)
0.474 (88)
2a
2b
2c
0.528
0.556
0.711
e
1H NMR (500 MHz, CDCl3)
d 19.43 (s, 1H), 7.35 (d, 2H), 7.21
(d, 2H), 7.17 (bs, 1H), 7.16 (t, 3H), 7.05 (bs, 1H), 7.01 (t, 6H), 6.96
(bs, 1H), 6.91 (t, 6H), 6.72 (bs, 1H), 6.68 (t, 3H), 6.57 (d, 2H), 2.43
(s, 6H), 2.04 (s, 6H). 13C NMR (125 MHz, CDCl3)
d
306.6
2e
0.482
e
(t), 187.8, 187.0, 151.1, 151.1, 139.1, 138.6, 138.0, 137.4, 137.3, 136.7,

S. Wolf, H. Plenio / Journal of Organometallic Chemistry 695 (2010) 2418e2422
2421
134.3, 134.2, 134.0, 133.8, 130.8, 130.5, 130.4, 129.8, 129.4, 129.2,
129.1, 128.9, 128.8, 128.7, 128.6, 128.2, 127.8, 127.8, 127.7, 124.5,
(125 MHz, CDCl3) d 303.1, 303.1, 197.9, 196.5, 190.4, 190.0, 151.6,
151.5,139.3,137.6, 134.1,134.0, 132.3, 132.2, 132.1,130.3, 130.2, 130.0,
129.8, 129.4, 128.8, 128.8, 128.7, 128.4, 124.4, 122.2, 121.8, 121.2,
120.3, 120.2, 54.6, 52.3, 37.3, 37.1, 31.1, 30.5, 29.6, 29.4, 29.0, 28.9,
27.1, 26.6, 25.1, 23.3, 23.0, 21.7, 19.9, 18.2. HR-MS (EI) calcd for
124.0, 20.0, 18.6. 31P NMR (121 MHz, CDCl3)
d 37.4. MS (ESI): m/z:
795.3 (M ꢁ Cl), 307.3 (C21H27N2).
ꢃ
4.1. General procedure for the synthesis of complexes 2aed and
6aef
C33H37N5O2Cl2Ru (Mþ ) 707.1359, found 707.13875.
4.1.5. Complex 6e
A dry Schlenk flask containing the respective [(NHC)(PPh3)
RuCl2(CHPh)] complex 4 or 5 (0.086 mmol) and [AgI(NHCewg)]
(0.094 mmol, 1.1 equiv) was evacuated and flushed with argon two
times. Toluene (5 mL) was added via a syringe and the reaction
mixture was stirred at 60 ꢀC for 30 min. The volatiles were evap-
orated and the residue purified by column chromatography. The
crude product was dissolved in minimal amount of CH2Cl2 and this
solution added to pentane (40 mL) to slowly precipitate green
microcrystalline material, which was collected by decantation of
the mother liquor.
Chromatography (cyclohexane/EtOAc ¼ 2:1), it is necessary to
use a short column and degassed eluent to obtain the green micro-
crystalline product, yield 48 mg (85%). 1H NMR (500 MHz, CDCl3)
d
19.46 (s,1H), 7.74 (d, 2H), 7.44 (t,1H), 7.33 (t,1 H), 7.25 (s, 2H), 7.16 (s,
3H), 7.09 (t, 3H), 7.05 (bs, 1H), 6.64 (d, 1H), 6.52 (d, 1H), 3.33 (s, 3H),
2.62 (s, 3H) 2.51 (bs, 12H). 13C NMR (125 MHz, CDCl3)
301.2, 192.9,
d
186.1, 151.6, 139.6, 139.5, 137.9, 137.0,129.9, 129.6, 129.0, 128.8,128.1,
124.1, 122.6, 122.2, 60.5, 37.3, 37.0, 29.8, 19.9, 18.4. HR-MS (EI) calcd
ꢃ
for C31H34N4Cl2Ru (Mþ ) 634.1196, found 634.12134.
4.1.6. Complex 6f
4.1.1. Complex 6a
Chromatography (cyclohexane/EtOAc ¼ 2:1), it is necessary to
use a short column and degassed eluent to obtain the green
microcrystalline product, yield 88%. Two rotamers 0.8:1, 1H NMR
Chromatography (cyclohexane/EtOAc ¼ 5:1), green microcrys-
talline, yield 61 mg (91%).
1H NMR (500 MHz, CDCl3)
d
19.68 (s, 1H), 8.98 (bs, 1H), 7.45 (t,
(500 MHz, CDCl3) d 19.60 (s, 0.8H), 19.50 (s, 1H), 7.77 (bs, 1.8 H),
2H), 7.38 (t, 4H), 7.34 (s, 1H), 7.33 (s, 1H), 7.30 (s, 2H), 7.29 (s, 1H),
6.39 (bs, 1H), 4.66 (septet, 1H), 3.65 (septet, 1H), 2.68 (bs, 3H), 2.50
(bs, 3H), 2.34 (bs, 3H), 1.62 (bs, 3H), 1.46 (d, 3H), 1.25 (d, 3H), 1.19
7.45e7.01 (m, 19.7H), 6.78 (s, 1.2 H), 6.67 (s, 1.2 H), 6.63 (s, 1.2H),
6.54 (s, 1H), 6.50 (bs, 0.8H), 4.42 (septet, 0.79H), 3.40 (septet, 1H),
3.30 (s, 3H), 2.69 (bs, 3H), 2.55 (s, 3H), 2.53 and 2.34 (overlapping
bs, 10.2H), 1.62 (bs, 4H), 1.43 (s, 1.4H), 1.26 (s, 1.4H), 1.21 (bs, 4.4H),
(d, 3H), 0.95 (d, 3H). 13C NMR (125 MHz, CDCl3)
d 301.1, 190.5, 189.1,
151.9,151.7,139.5,138.8,138.5, 137.3,136.8,131.9,129.9,129.4,129.2,
128.8, 128.4, 128.1, 127.7, 124.6, 124.5, 124.3, 116.5, 115.8, 56.8, 54.2,
53.8, 29.8, 22.2, 22.1, 21.7, 19.8, 19.3, 18.8, 18.0. HR-MS (EI) calcd for
0.85 (bs, 4.4H), 0.34 (bs, 2.8H). 13C NMR (125 MHz, CDCl3)
d 301.4,
298.1,192.9,192.6, 185.5,185.4, 151.7,151.6,139.7,139.5, 139.3, 138.8,
138.2, 138.0,137.1,136.8,130.5,130.1,129.6,129.0,128.7,128.2,128.1,
124.1, 123.3, 122.9, 117.1, 116.4, 52.5, 50.2, 37.3, 36.7, 29.8, 27.0, 25.0
(br s), 20.0, 19.9, 18.8, 18.4, 18.0. HR-MS (EI) calcd for C33H38N4Cl2Ru
ꢃ
C35H38N6Cl2Ru (Mþ ) 714.1566, found 714.1571.
ꢃ
4.1.2. Complex 6b
(Mþ ) 662.1509, found 662.15734.
Chromatography (cyclohexane/EtOAc ¼ 5:1), green microcrys-
talline, yield 60 mg (93%).
4.1.7. Complex 2a
Two rotamers 0.7:1, 1H NMR (500 MHz, CDCl3)
d
19.59 (s, 0.7H),
Chromatography (cyclohexane/EtOAc ¼ 4:1), green microcrys-
19.50 (s, 1H), 7.75 (bs, 1.4H), 7.49e7.00 (overlapping triplets,
19.3H), 6.49 (bs, 1H), 4.60 (septet, 0.7H), 3.66 (septet, 1H), 3.25
(s, 3H), 2.69e2.32 (m, 18H), 1.61 (bs, 3.5H), 1.43 (s, 1H), 1.36e1.26
(m, 5H), 0.98e0.86 (m, 5H), 0.45 (bs, 2.8H). 13C NMR (125 MHz,
talline, yield 94%.
4.1.8. Complex 2b
Chromatography (cyclohexane/EtOAc ¼ 4:1), green microcrys-
CDCl3)
d
304.8, 301.2, 191.1, 190.8, 188.5, 151.7, 139.4, 137.8, 137.1,
talline, yield 92%.
130.6 (br s), 130.3, 129.9, 129.8, 129.4, 129.4, 129.2, 128.8, 128.4,
128.3, 124.3, 118.5, 118.4, 114.8, 114.2, 56.8, 54.2, 35.5, 35.0, 32.1,
29.8, 29.8, 29.5, 22.8, 22.2, 20.0, 19.8, 14.2. HR-MS (EI) calcd for
C33H36N4Cl4Ru (Mþ ) 730.072, found 730.07287.
4.1.9. Complex 2c
Chromatography (cyclohexane/EtOAc ¼ 2:1), it is necessary to
use short column and degassed eluent to obtain the green micro-
crystalline product, yield 81%.
ꢃ
4.1.3. Complex 6c
Chromatography (cyclohexane/EtOAc ¼ 4:1), green microcrys-
4.1.10. Complex 2d
Chromatography (cyclohexane/EtOAc
microcrystalline, yield 89%.
talline, yield 57 mg (94%).
¼
4:1), redebrown
1H NMR (500 MHz, CDCl3)
d 19.34 (s, 1H), 7.68 (bs, 2H), 7.54 (t,
1H), 7.40 (bs, 2H), 7.29e7.20 (m, 4H), 7.17 (t, 2H), 7.08 (bs, 1H), 6.99
Spectroscopic data for complexes 2aef are in accord with
(bs, 1H), 3.52 (s, 3H), 2.74 (s, 3H), 2.47 (bs, 6H), 2.06 (bs, 3H), 2.04 (s,
literature data [13].
1H), 1.54 (s, 1H), 1.43 (s, 1H). 13C NMR (125 MHz, CDCl3)
d 309.3,
200.7, 189.1, 151.4, 139.5, 139.1, 137.4, 137.0, 130.7, 130.2, 130.1, 129.5,
128.8, 128.7, 124.3, 115.6, 115.5, 107.0, 106.9, 60.5, 37.3, 37.1, 27.1,
Acknowledgements
ꢃ
20.0, 18.2. HR-MS (EI) calcd for C33H32N6Cl2Ru (Mþ ) 684.1101,
This work was supported by the DFG.
found 684.10952.
References
4.1.4. Complex 6d
Chromatography (cyclohexane/EtOAc
microcrystalline, yield 56 mg (90%). Two rotamers 0.35:1, 1H NMR
(500 MHz, CDCl3) 19.48 and 19.47 (overlapping singlets, 1H), 7.82
(s, 0.3H), 7.64 (s, 0.7H), 7.52e6.97 (m, 12.3H), 6.49 (bs, 0.7H), 4.53
(septet, 0.3H), 3.63 (s, 2.1H), 3.48 (septet, 0.8H), 2.83 (s, 0.9H),
2.67e2.31 (m, 8.6H), 1.68e1.13 (m, 7.8H), 0.36 (bs, 1.6H). 13C NMR
¼
4:1), redebrown
[1] S. Leuthäußer, D. Schwarz, H. Plenio, Chem. Eur. J. 13 (2007) 7195e7203.
[2] S. Leuthäußer, V. Schmidts, C.M. Thiele, H. Plenio, Chem. Eur. J. 14 (2008)
5465e5481.
[3] M. Alcarazo, R. Fernández, E. Álvarez, J.M. Lassaletta, J. Organomet. Chem. 690
(2005) 5979e5988.
d
[4] D.M. Khramov, E.L. Rosen, J.A.V. Er, P.D. Vu, V.M. Lynch, C.W. Bielawski,
Tetrahedron 64 (2008) 6853e6862.

2422
S. Wolf, H. Plenio / Journal of Organometallic Chemistry 695 (2010) 2418e2422
[5] U. Siemeling, C. Färber, C. Bruhn, Chem. Commun. (2009) 98e100.
[6] E.L. Rosen, C.D. Varnado, A.G. Tennyson, D.M. Khramov, J.W. Kamplain, D.H. Sung,
P.T. Cresswell, V.M. Lynch, C.W. Bielawski, Organometallics 28 (2009) 6695e6706.
[7] V. César, N. Lugan, G. Lavigne, Eur. J. Inorg. Chem. (2010) 361e365.
[8] C. Samoj1owicz, M. Bieniek, K. Grela, Chem. Rev. 109 (2009) 3708e3742.
[9] T. Weskamp, F.J. Kohl, W. Hieringer, D. Gleich, W.A. Herrmann, Angew. Chem.
Int. Ed. 38 (1999) 2416e2419.
[10] T.W. Hudnall, C.W. Bielawski, J. Am. Chem. Soc. 131 (2009) 16039e16041.
[11] N. Ledoux, A. Linden, B. Allaert, H.V. Mierde, F. Verpoort, Adv. Synth. Catal. 349
(2007) 1692e1700.
[17] E. Poverenov, D. Milstein, Chem. Commun. (2007) 3189e3191.
[18] P. Schwab, R.H. Grubbs, J.W. Ziller, J. Am. Chem. Soc. 118 (1996) 100e110.
[19] R. Dorta, R.A. Kelly, S.P. Nolan, Adv. Synth. Catal. 346 (2004) 917e920.
[20] L.H. Peeck, H. Plenio, Organometallics 29 (2010) 2761e2768.
[21] W. Zhang, C. Bai, X. Lu, R. He, J. Organomet. Chem. 692 (2007)
3563e3567.
[22] W.-Z. Zhang, R. He, R. Zhang, Eur. J. Inorg. Chem. (2007) 5345e5352.
[23] J.K. Huang, E.D. Stevens, S.P. Nolan, J.L. Petersen, J. Am. Chem. Soc. 121 (1999)
2674e2678.
[24] C.K. Chung, R.H. Grubbs, Org. Lett. 10 (2008) 2693e2696.
[25] I.C. Stewart, C.J. Douglas, R.H. Grubbs, Org. Lett. 10 (2008) 441e444.
[26] K.M. Kuhn, J.-B. Bourg, C.K. Chung, S.C. Virgil, R.H. Grubbs, J. Am. Chem. Soc.
131 (2009) 5313e5320.
[27] D.M. Khramov, V.M. Lynch, C.W. Bielawski, Organometallics 26 (2007)
6042e6049.
[12] T. Vorfalt, S. Leuthäußer, H. Plenio, Angew. Chem. Int. Ed. 48 (2009)
5191e5194.
[13] V. Sashuk, L.H. Peeck, H. Plenio, Chem. Eur. J. 16 (2010) 3983e3993.
[14] M.S. Sanford, J.A. Love, R.H. Grubbs, Organometallics 20 (2001) 5314e5318.
[15] T.R. Belderrain, R.H. Grubbs, Organometallics 16 (1997) 4001e4003.
[16] M. Gandelman, K.M. Naing, B. Rybtchinski, E. Poverenov, Y. Ben-David,
N. Ashkenazi, R.M. Gauvin, D. Milstein, J. Am. Chem. Soc. 127 (2005)
15265e15272.
[28] S. Wolf, H. Plenio, J. Organomet. Chem. 694 (2009) 1487e1492.
[29] C. Hansch, A. Leo, R.W. Taft, Chem. Rev. 91 (1991) 165e195.
[30] M. Süßner, H. Plenio, Chem. Commun. (2005) 5417e5419.