Alkyl group-tagged ruthenium indenylidene complexes: Synthesis, characterization and metathesis activity

Article abstract of DOI:10.1016/j.jorganchem.2015.04.054

We report on the synthesis of ruthenium indenylidene catalysts [RuCl₂(3-R-1-indenylidene)(PCy₃)₂ in which R is iso-propyl (7a), tert-butyl (7b) or cyclohexyl (7c)]. The obtained alkyl tagged indenylidene catalysts were ana

Full text of DOI:10.1016/j.jorganchem.2015.04.054

Journal of Organometallic Chemistry 791 (2015) 148e154
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Alkyl group-tagged ruthenium indenylidene complexes: Synthesis,
characterization and metathesis activity
Baoyi Yu b, Fatma B. Hamad d, Karen Leus b, Alex A. Lyapkov c, Kristof Van Hecke b,
, b, c, *
Francis Verpoort a
a Laboratory of Organometallics, Catalysis and Ordered Materials, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,
School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China
b Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
c National Research Tomsk Polytechnic University, Tomsk, Russian Federation
d Dar es Salaam University College of Education, Faculty of Science, Department of Chemistry, P.O. Box 2329, Dar es Salaam, Tanzania
a r t i c l e i n f o
a b s t r a c t
Article history:
We report on the synthesis of ruthenium indenylidene catalysts [RuCl2(3-R-1-indenylidene)(PCy3)2 in
which R is iso-propyl (7a), tert-butyl (7b) or cyclohexyl (7c)]. The obtained alkyl tagged indenylidene
catalysts were analyzed by means of IR, elemental analysis, NMR and single crystal X-Ray diffraction
analysis. Furthermore, the catalytic performance of these new complexes was examined in different
metathesis reactions: ring-closing metathesis (RCM), ring-closing ene-yne metathesis (RCEYM), ring-
opening metathesis polymerization (ROMP) and cross metathesis (CM), exhibiting a comparable activ-
ity in comparison with the commercially available catalyst 3a.
Received 1 March 2015
Received in revised form
14 April 2015
Accepted 28 April 2015
Available online 2 June 2015
Keywords:
Olefin metathesis
Ruthenium
© 2015 Elsevier B.V. All rights reserved.
Indenylidene
Homogeneous
Catalysis
1. Introduction
catalysts have also been well-studied, for example complex 3a [6].
The peculiar attribution of ruthenium indenylidene catalysts is
Olefin metathesis as a powerful synthesis tool plays an impor-
tant role in synthetic chemistry [1]. The suitability of ruthenium
based olefin metathesis catalysts over other transition metals is
based on their ability to combine both high activity and excellent
stability [2]. Since the discovery of the 1st generation ruthenium
benzylidene catalyst 1a (Fig. 1) by Grubbs and coworkers [3], the
great focus of metathesis pioneers has been on the development of
new catalysts with enhanced catalytic performance. A notable
development was the substitution of one of the labile phosphines
by N-heterocyclic carbenes (NHC), which resulted in the more
stable 2nd generation catalyst 1b [4]. Another important contri-
bution in this area was the development of the chelating benzyli-
dene Grubbs-Hoveyda type catalyst 2, which showed an increased
stability in comparison to complex 1a [5]. Besides ruthenium
their ease of synthesis [7], and increased stability under harsh
conditions. Additionally, they exhibit a comparable (or sometimes
higher) catalytic performance than their benzylidene counterparts
[7a,8]. Furthermore, the ruthenium indenylidene catalysts were
often employed as starting materials for the synthesis of other
families of ruthenium catalysts, e.g. benzylidene [9] or ether
chelating benzylidene catalysts [10].
The ease of synthesis and high catalytic performance of ruthe-
nium indenylidene catalysts have encouraged some researchers to
modify these basic indenylidene structures. In 2010, the catalyst 4a,
bearing the bidentate iso-propoxyindenylidene ligand, was re-
ported by Bruneau's group which was an analogue of complex 2.
Although a lower catalytic initiation speed was observed, the re-
ported complex showed improved thermal stability in comparison
with its benzylidene analogue 2 [11]. Later on, substituted variants
with the general structure of 4b of the chelating indenylidene
complexes were reported by the same group [12]. Moreover,
Schrodi et al. reported on the in-situ generated methoxy coordi-
nated bidentate indenylidene catalyst 4c, which showed a com-
parable activity to complex 2 [13]. Recently, we have reported the
benzylidene catalysts
1 and 2, the ruthenium indenylidene
* Corresponding author. Department of Inorganic and Physical Chemistry, Ghent
University, Krijgslaan 281-S3, 9000 Ghent, Belgium.
E-mail address: Francis.verpoort@ugent.be (F. Verpoort).
http://dx.doi.org/10.1016/j.jorganchem.2015.04.054
0022-328X/© 2015 Elsevier B.V. All rights reserved.

B. Yu et al. / Journal of Organometallic Chemistry 791 (2015) 148e154
149
reactions yielding complexes 6a-c were monitored by 31P NMR
spectroscopy. The reaction solutions all showed a dark red color
after 10 min and according to the 31P NMR spectra the reactions
were finished. Single phosphine peaks for each compound were
observed at 29.6 ppm for 6a, 29.1 ppm for 6b and 29.5 ppm for 6c
from the 31P NMR spectra (see Fig. S.4,6,8), after purification by
simply washing with n-hexane and methanol. The structural con-
figurations of 6a-c were confirmed by single crystal X-ray analysis
(see the section “Single crystal X-ray diffraction analysis”). Later on,
complexes 7a-c were obtained by the exchange of the PPh3 on 6a-c
by PCy3 in dichloromethane (Scheme 1) as reddish brown solids in
high yield (91e95%) after washing with n-pentane. The purities of
the obtained complexes 7a-c were analyzed by elemental analysis.
The characterization of 7a-c was done by means of IR, NMR and
single crystal X-ray diffraction (see the section “Single crystal X-ray
diffraction analysis”). For the NMR data, assignment of each proton
and carbon resonance of the 1H- (see Fig. S.9,12,15) and 13C{1H} (see
Fig. S.10,13,16) NMR spectra was achieved by a combination of the
1D and 2D (1H{1H}COSY, 1H{13C}HSQC and HMBC) NMR data (see
the section of “Structure elucidation of NMR spectral data” in the
ESI).
Fig. 1. Ruthenium based olefin metathesis catalysts.
synthesis of first generation ruthenium indenylidene complexes
3b-d featuring a functionalized 3-phenyl group based on the gen-
eral scaffold of complex 3a, the resulting complexes showed com-
parable catalytic activity relative to the reference catalyst 3a [14].
So far, all the reported ruthenium indenylidene catalysts were
derived from 1,1-diaryl-propargylic alcohols [11e13,15]. Neverthe-
less, only one of the two aryl groups is necessary to be involved in
the indenylidene formation process. Some attempts for obtaining
ruthenium indenylidene complexes from a mono aryl propargylic
alcohol were not successful [13b,16]. Herein, we report on the
successful synthesis of ruthenium indenylidene catalysts employ-
ing a library of 1-alkyl-1-phenyl-2-propyn-1-ol ligands. The char-
acterization and catalytic activity of the obtained first generation
single species with the general structure of RuCl2(3-alkyl-1-
indenylidene)(PCy3)2 are described.
2.1. Single crystal X-ray diffraction analysis
Crystallization of 6a-c was carried out by incubation of reaction
solutions at room temperature for two days affording crystals,
suitable for X-ray structure determination. Their structures are
shown in Fig. 2.
Compounds 6a and 6c crystallized both in the centro-symmetric
triclinic space group P-1, while compound 6b crystallized in the
centro-symmetric monoclinic space group I2/a. The asymmetric
unit of the structures consists of one ruthenium complex molecule
and additional dioxane solvent molecules (one dioxane molecule
for 6a, two-and-a-half for 6b and three for 6c). For 6a, the 3-iso-
propyl-1-indenylidene moiety is completely disordered over two
2. Results and discussion
A convenient way to obtain a ruthenium based alkylidene
catalyst (vinylidene [17], allenylidene [6c,18] and indenylidene
[7a,12,19]) is the direct treatment of non-hazardous propargylic
alcohols with RuCl2(PPh3)3 [20]. However, the ruthenium inden-
ylidene catalysts were generally preferred among these three
families since they showed a relatively more active performance in
olefin metathesis reactions in comparison to their vinylidene or
allenylidene analogues [15b]. Especially, the latter two catalysts
types could be decomposed by H2O [21] or O2, [22] consequently,
the cleavage of the Ca ¼ Cb bond resulted in a formation of a CO
ligand. Thus, in terms of catalyst efficiency and hence the cost
effectiveness of the expensive ruthenium used, ruthenium inden-
ylidene catalysts are more preferred [15b,20c,f]. The indenylidene
precursor complex 3a could be obtained from a well-established
general strategy, which involves the reaction of RuCl2(PPh3)3 and
1,1-diphenyl-2-propyn-1-ol in THF/dioxane in presence of acid and
followed by an exchange of PPh3 with PCy3 [7b].
The propargylic alcohols 5a [23], 5b [24] and 5c [25] (Scheme 1)
were prepared by direct addition of ethynylmagnesium bromide to
the relative keton in THF and were purified by column chroma-
tography. Subsequently, 5a-c were allowed to react with
RuCl2(PPh3)3 in dioxane in the presence of HCl at 90 ꢀC [26]. The
Fig. 2. ORTEP representations of the structures of complexes 6a-c (thermal ellipsoids
are shown at the 30% probability level), showing the atom labeling scheme of the
heteroatoms and carbon atom C1 and C1A. Hydrogen atoms and dioxane solvent
molecules are omitted for clarity. For 6a, the disorder of the 3-iso-propyl-1-
indenylidene moiety is omitted for clarity.
Scheme 1. Synthesis of complexes 7a-c from 5a-c.

150
B. Yu et al. / Journal of Organometallic Chemistry 791 (2015) 148e154
positions, turned over about 175.8ꢀ with respect to each other.
Complexes 6a-c feature a slightly distorted square-pyramidal ge-
ometry around the ruthenium atom, similar to complexes 1a [27]
and 3a [28], with the indenylidene moieties in the axial position.
The Ru]C bond lengths for 6a and 6c are 1.861(6)/1.85(3) and
1.869(5) Å, respectively, while these values are slightly longer than
the one for 6b (1.833(8) Å) (Table 1). The RueCl bond lengths for 6a-
c are found between 2.345(1) and 2.375(1) Å and RueP bond
lengths range from 2.370(2) to 2.400(2) Å. PeRueP and CleRueCl
angles for these three species are within 166e169ꢀ and 158e160ꢀ,
respectively.
Crystals, suitable for X-ray diffraction analysis, of 7a-c were
grown from a fast evaporation (a few seconds) of a dichloro-
methane solution of complexes on a glass slide. Their structures are
shown in Fig. 3.
Apparently, all complexes 7a-c crystallized in the R-3 trigonal
space group with one ruthenium complex in the asymmetric unit.
Similar to 1a [27], 3a [28] and 6a-c, a square-pyramidal geometry
around the ruthenium center is observed for 7a-c. Some selected
structural data of complexes 7a-c are listed in Table 1, in compar-
ison with complex 1a and the parent complex 3a. Complexes 7a-c
exhibit Ru]C bond lengths of 1.869(5), 1.858(8) and 1.860(6) Å,
respectively, while complex 1a and 3a show Ru]C bond lengths of
1.841(2) Å and 1.882(6) Å, respectively. The bond distances of RueCl
are quite similar for 1a, 3a and 7a-c, and are all in the range of
2.385(2)-2.408(2) Å. Considering the RueP bond lengths, all the
bond lengths are between 2.4030(7) and 2.427(2) Å for all the
species 1a, 3a and 7a-c. The CleRueCl angles for the new species
and 3a can be summarized in a value of 164ꢀ without significant
differences, while the angle is 167ꢀ for 1a, which is obviously larger
than the ones for the former indenylidene complexes. 7a-c show
PeRueP bond angles of 161ꢀ in comparison with 1a and 3a (162ꢀ
and 159ꢀ, respectively). Potential intramolecular hydrogen bonds
are observed between the indenylidene ligand and the chlorides for
7a-c: C2eH2/Cl2 and C7eH7/Cl1 (C/Cl distance of 3.19e3.25 Å)
(number scheme see Fig. S.1).
Fig. 3. ORTEP representations of the structures of complexes 7a-c (thermal ellipsoids
are shown at the 30% probability level), showing the atom labeling scheme of the
heteroatoms and carbon atom C1. Hydrogen atoms are omitted for clarity.
2.2. Catalytic activity studying in olefin metathesis reactions
The catalytic performance of the new complexes 7a-c was tested
in some well-established model olefin metathesis reactions [7a,29].
More specifically, in the ring-closing metathesis (RCM) of diethyl
2,2-diallylmalonate (8) (Scheme 2, a), the ring-opening metathesis
polymerization (ROMP) of cis,cis-cycloocta-1,5-diene (COD)
(Scheme 2, b), the ring-closing ene-yne metathesis (RCEYM) of (1-
(allyloxy)prop-2-yne-1,1-diyl)dibenzene (9) (Scheme 2, c) and the
cross metathesis (CM) between allylbenzene and cis-1,4-diacetoxy-
2-butene (Scheme 2, d). The results of all the catalytic tests are
depicted in Figs. 4e7.
Scheme 2. Olefin metathesis model reactions a, b, c, d.
as well as 3a showed a similar conversion pattern and a similar
kinetics. After approximately 30 min of reaction, complexes 7b and
7c exhibited a conversion of 93% whereas for complex 7a, a con-
version of 90% was noted, which was comparable to the catalytic
Fig. 4 displays the catalytic performance of 7a-c in comparison
with 1a and 3a for the RCM of 8 (Scheme 2, a). A catalyst loading of
0.5 mol% was applied at 20 ꢀC in CDCl3. All the new complexes 7a-c
Table 1
Selected bond lengths (Å) and angles (ꢀ) for complexes 6a-c and 7a-c in comparison with 1a and 3a.
6a
6b
6c
1aa
3ab
7a
7b
7c
Ru¼C
1.861(6)/1.85(3)
2.3577(7)
2.3686(7)
2.3776(9)
2.395(1)
1.833(8)
2.367(2)
2.362(2)
2.375(2)
2.400(2)
168.01(8)
157.52(8)
1.869(5)
2.345(1)
2.374(1)
2.396(1)
2.370(2)
169.00(5)
158.35(5)
1.841(2)
1.882(6)
2.389(2)
2.408(2)
2.427(2)
2.416(2)
159.03(7)
163.91(7)
1.869(5)
2.392(1)
2.389(1)
2.414(2)
2.416(2)
160.69(6)
163.88(6)
1.858(8)
2.393(2)
2.385(2)
2.416(2)
2.413(1)
160.92(7)
163.84(7)
1.860(6)
2.389(2)
2.395(2)
2.419(2)
2.418(2)
160.63(7)
164.06(7)
RueCl
2.3949(6)
2.3957(6)
2.4030(7)
2.4066(7)
162.22(2)
166.87(2)
RueP1
RueP2
PeRueP
CleRueCl
165.99(3)
160.10(3)
a
Data according to reference [27].
Data according to reference [28].
b

B. Yu et al. / Journal of Organometallic Chemistry 791 (2015) 148e154
151
Fig. 4. RCM of 8 (Scheme 2a) with complexes 1a, 3a and 7a-c (0.5 mol%) at 20 ꢀC in
CDCl3. Lines are intended as visual aid.
Fig. 7. CM between allylbenzene and cis-1,4-diacetoxy-2-butene (Scheme 2, d)
applying catalyst loading of 2.5 mol% at 25 ꢀC in dichloromethane. Lines are intended
as visual aid.
performance of the reference complex 3a. In contrast, the first
generation Grubbs catalyst 1a exhibited a faster initiation while a
much lower conversion was observed (about 62%) in comparison to
its indenylidene analogues [29].
The conversion patterns for the ROMP of COD (Scheme 2, b)
using catalysts 3a and 7a-c are depicted in Fig. 5. The catalytic
performance of complex 3a in the ROMP of COD was in agreement
with previous report [30]. Moreover, as can be seen from Fig. 5, all
the new species showed a similar catalytic efficiency as the refer-
ence complex 3a. No significant difference can be observed among
all the employed complexes 3a and 7a-c in any stage of the
reaction.
Furthermore, all the synthesized complexes were examined in
the RCEYM of substrate 9 (Scheme 2, c) and the CM between
allylbenzene and cis-1,4-diacetoxy-2-butene (Scheme 2, d). Also in
the latter two catalytic tests, the novel catalysts exhibited a similar
metathesis activity as the benchmark catalyst 3a (Figs. 6 and 7).
All these indenylidene complexes 3a and 7a-c showed a similar
catalytic performance in all the investigated olefin metathesis re-
actions, however, they showed a better overall performance than
the Grubbs first generation catalyst 1a in the RCM reaction of
substrate 8.
Fig. 5. ROMP of COD (Scheme 2, b) with complexes 3a and 7a-c (0.033 mol%) at 25 ꢀ
in CDCl3. Lines are intended as visual aid.
C
The effect of a modification of the alkylidene moieties on the
catalytic activities could be either via electronic influences [31] on
the ruthenium center or via steric repulsion between the sur-
rounding ligands [32]. In our case, we believe that the indenylidene
fragment, between the ruthenium center and the modified sites,
suppresses the electronic effect from the phenyl (3a) or alkyl (7a-c)
groups.
Considering the steric aspect, it was reported that the interac-
tion between a bulkier NHC and indenylidene ligands could stim-
ulate the dissociation of PCy3, therefore resulting in a high initiation
rate of the ruthenium indenylidene catalyst [32]. In comparison
with second generation type catalysts, the dissociation rate of PCy3
of first generation type catalysts is relatively faster [33]. As a matter
of fact, _ENREF_53the reaction rate of first generation type catalysts
is not dependent on the dissociation of PCy3, in other words, the
dissociation of phosphine is not the rate determining step for first
generation catalysts, which was revealed by Grubbs group [33a].
Therefore, the function of steric stimulation to release the PCy3
group to achieve faster catalysts initiation for a first generation type
catalyst was reduced. Especially, in our study, as can be seen from
Fig. 6. RCEYM of 9 (Scheme 2, c) with complexes 3a and 7a-c (5 mol%) at 50 ꢀC in
toluene. Lines are intended as visual aid.

152
B. Yu et al. / Journal of Organometallic Chemistry 791 (2015) 148e154
Table 1, most of the bond lengths and bond angles in complexes 7a-
c are similar to these in complex 3a, no significant steric interaction
was noted between the investigated modified parts (3-alkyl
groups) and any of the two PCy3 groups. So, we believe that the
similarity of the catalytic performance of the investigated inden-
ylidene catalysts is probably due to the resemblance of their
configuration around the ruthenium center.
the ShelXL program [39]. Non-hydrogen atoms were anisotropi-
cally refined and the hydrogen atoms in the riding mode and
isotropic temperature factors fixed at 1.2 times U(eq) of the parent
atoms (1.5 times for methyl groups). CCDC-1032813e1032818
contain the Supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
3. Conclusions
Structure elucidation of NMR spectral data of 7a-c. Standard
benchmark screening procedures were done following the litera-
ture and applied details as well as NMR spectra of 6a-c and 7a-c
were also listed in the Supporting information.
The current work extends the scope of ligands, which can be
employed to generate ruthenium indenylidene catalysts from the
previous reported 1,1-diaryl-propargylic alcohols to the 1-alkyl-1-
phenylpropargylic alcohols. A new library of ruthenium inden-
ylidene complexes has been synthesized successfully and has been
characterized by means of IR, elemental analysis, NMR and single
crystal X-ray diffraction. The X-ray diffraction data demonstrate
that all complexes exhibiting quite similar values for both the bond
lengths and angles of these ligands around the ruthenium center.
Moreover, the catalytic activity of these complexes was examined
in various model olefin metathesis reactions. As a result, no sig-
nificant difference in catalytic performance was observed among
the new catalysts themselves nor between the new catalysts and
the reference catalyst 3a. The changes in the geometry from the
phenyl group (3a) by the alkyl groups (7a-c) showed negligible
effect on the catalytic activity on these first generation ruthenium
indenylidene complexes.
4.2. General synthesis condition for the ruthenium complexes 6a-c
and 7a-c
The RuCl2(PPh3)3 (1 eq., 0.50 mmol) was added to the prop-
argylic alcohols 5 (1.3 eq., 0.65 mmol) in 5 mL HCl/dioxane solution
(0.1 mol/L). The reaction mixture was heat up in an oil bath at 90 ꢀC
and was monitored by 31P NMR. The reaction was completed after
only 10 min of reaction. Afterwards, all the volatiles were removed
under vacuum and hexane (20 mL) was added. The flask was placed
in an ultrasonic bath until the solid was homogenously distributed.
The resulting suspension was filtered and washed with n-hexane
and methanol affording a red-brown powder. The products 6 were
measured by 1H and 31P NMR spectroscopy. Single crystal of 6
suitable for X-ray diffraction analysis was obtained by incubation of
the reaction solution at room temperature for two days.
In a second step, the obtained ruthenium complex 6 was mixed
with tricyclohexylphosphine (3.0 eq., 1.5 mmol) in dry dichloro-
methane (10 mL) under argon atmosphere and vigorously stirred at
room temperature. The reaction was monitored by 31P NMR. After
completion of the reaction (about 3 h), the resulting slurry was
dried under vacuum and cold n-pentane (5 mL) was added.
Filtration afforded a red-brown powder, which was afterwards
washed with cold n-pentane (2 x 5 mL) and drying under vacuum
affording the reddish brown powder 7. Single crystal of 7 suitable
for X-ray diffraction analysis was grown from a fast evaporation of
the complex dichloromethane solution on a glass slide.
4. Experimental section
4.1. General consideration
All the reactions were carried out under argon atmosphere.
Solvents were dried and freshly distilled prior to use. For drying
dichloromethane, CaH2 was used as drying agent whereas for
toluene, n-hexane, n-pentane and 1,4-dioxane, sodium was
employed as drying agent and benzophenone was used as indica-
tor. The compounds RuCl2(PPh3)3 [34], 4-methyl-3-phenyl-1-
pentyn-3-ol [23], 4,4-dimethyl-3-phenyl-1-pentyn-3-ol [24], 1-
cyclohexyl-1-phenyl-2-propyn-1-ol [25] and (1-(allyloxy)prop-2-
yne-1,1-diyl)dibenzene [35] were prepared according to the liter-
ature. n-Hexane, n-pentane, 1,4-dioxane and toluene were pur-
chased from Fiers. Diethyl 2,2-diallylmalonate, HCl in 1,4-dioxane
(1M), benzophenone, cis,cis-cycloocta-1,5-diene and allylbenzene
were bought from Aldrich. cis-1,4-diacetoxy-2-butene was ob-
tained from ABCR.
The 1D and 2D NMR spectra were recorded on Bruker Avance
300 MHz and 500 MHz spectrometers. Chemical shifts were listed
in ppm using tetramethylsilane with residual solvent resonance as
an internal standard (1H, 13C) or external standard H3PO4 (31P). The
exact indicated number of each assigned proton and carbon of the
new complexes could be found from Fig. S.1 in the supporting
information. Elemental analyses were performed on a CHNS-
0 Analyzer from Interscience. Gas chromatography measurements
were carried out on a Agilent 7890A instrument equipped with a
flame ionization detector and an HP-5 5% phenyl methyl siloxane
column (DB-5, column length: 30 m, inside diameter: 0.25 mm,
outside diameter: 0.32 mm, film thickness: 0.25 mm). X-ray
diffraction data were collected on an Agilent Supernova Dual
Source (Cu at zero) diffractometer equipped with an Atlas CCD
4.2.1. RuCl2(3-iso-propyl-1-indenylidene) (PPh3)2, 6a
1H NMR (300 MHz, CDCl3, 20 ꢀC, TMS):
d 7.48e7.54 (m, 12H),
3
3
7.38 (t, JH,H ¼ 7.4 Hz, 6H), 7.27 (t, JH,H ¼ 7.5 Hz, 12H), 7.21 (t,
3JH,H ¼ 7.4 Hz, 1H), 6.95 (d, 3JH,H ¼ 7.2 Hz, 1H), 6.86 (d, 3JH,H ¼ 7.2 Hz,
1H), 6.53 (t, 3JH,H ¼ 7.4 Hz, 1H), 6.17 (s, 1H), 2.09 (sept, 3JH,H ¼ 6.6 Hz,
3
1H), 1.01 (d, JH,H ¼ 6.8 Hz, 6H); 31P{1H}NMR (121 MHz, CDCl3,
20 ꢀC):
d 29.6 (s); elemental analysis calcd (%) for C48H42Cl2P2Ru
(852.12): C 67.60, H 4.96; found: C 67.82, H 5.25.
4.2.2. RuCl2(3-iso-propyl-1-indenylidene) (PCy3)2, 7a
(0.42 g, 95%). 1H NMR (500 MHz, CDCl3, 20 ꢀC, TMS):
d 8.57 (d,
3JH,H ¼ 7.3 Hz,1H, H-7), 7.30 (t, 3JH,H ¼ 7.3 Hz,1H, H-5), 7.18e7.21 (m,
2H, H-2 and H-6), 6.95 (d, 3JH,H ¼ 7.0 Hz, 1H, H-4), 2.57e2.61 (m, 6H,
3
H-PCy3), 2.26 (sept, JH,H ¼ 6.7 Hz, 1H, H-10), 1.86e1.88 (m, 6H, H-
PCy3), 1.75 (s, 12H, H-PCy3), 1.66 (s, 12H, H-PCy3), 1.40e1.52 (m,12H,
H-PCy3), 1.15e1.24 (m, 24H, H-11, H-PCy3); 13C{1H}NMR (126 MHz,
CDCl3, 20 ꢀC):
d
297.8 (t, 2JC,P ¼ 7.6 Hz, C-1), 148.4 (C-3), 143.7 (C-8),
141.5 (C-9), 136.9 (C-2), 128.8 (C-7), 128.7 (C-6), 128.4 (C-5), 115.6
(C-4), 32.4e32.6 (C-PCy3), 29.7e29.8 (C-PCy3), 27.7e27.9 (C-PCy3),
27.3 (C-10), 26.6 (C-PCy3), 19.6 (C-11). 31P{1H}NMR (203 MHz,
detector using CuK
a
radiation (
l
¼ 1.54178 Å) and
u scans. All
images were interpreted and integrated with the program CrysA-
lisPro (Agilent Technologies) [36]. Using Olex2 [37], the structures
were solved by direct methods using the ShelXS structure solution
program [38] and refined by full-matrix least-squares on F2 using
CDCl3, 20 ꢀC):
d
31.4 (s). IR (Neat):
n
¼ 2929, 2851, 1549, 1446, 1360,
1345, 1328, 1301, 1266, 1222, 1199, 1174, 1129, 1109, 1046, 1004, 918,
916, 888, 847, 767, 754, 733, 708 cmꢁ1; elemental analysis calcd (%)
for C48H78Cl2P2Ru (888.40): C 64.85, H 8.84; found: C 64.78, H 8.92.

B. Yu et al. / Journal of Organometallic Chemistry 791 (2015) 148e154
153
4.2.3. RuCl2(3-tert-butyl-1-indenylidene) (PPh3)2, 6b
1H NMR (300 MHz, CDCl3, 20 ꢀC, TMS):
7.48e7.53 (m, 12H),
Appendix A. Supplementary data
d
3
3
7.38 (t, JH,H ¼ 7.2 Hz, 6H), 7.27 (t, JH,H ¼ 7.4 Hz, 12H), 7.20 (t,
3JH,H ¼ 7.4 Hz, 1H), 7.09 (d, 3JH,H ¼ 7.4 Hz, 1H), 7.02 (d, 3JH,H ¼ 7.2 Hz,
1H), 6.49 (t, 3JH,H ¼ 7.2 Hz, 1H), 6.19 (s, 1H), 1.11 (s, 9H); 31P{1H}NMR
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2015.04.054.
(121 MHz, CDCl3, 20 ꢀC):
d 29.1 (s); elemental analysis calcd (%) for
References
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49H44Cl2P2Ru (866.13): C 67.90, H 5.12; found: C 67.58, H 5.39.
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¼2910, 2854,1541,1447,1364,1346, 1329,1301,1259,
1198, 1183, 1175, 1129, 1110, 1004, 915, 896, 887, 848, 768, 754,
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3
3
7.38 (t, JH,H ¼ 7.4 Hz, 6H), 7.27 (t, JH,H ¼ 7.4 Hz, 12H), 7.19 (t,
3JH,H ¼ 7.5 Hz, 1H), 6.93 (d, 3JH,H ¼ 6.8 Hz, 1H), 6.85 (d, 3JH,H ¼ 7.2 Hz,
3
1H), 6.52 (t, JH,H ¼ 7.4 Hz, 1H), 6.15 (s, 1H), 1.70e1.81 (m, 6H),
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5.19; found: C 68.90, H 5.05.
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4.2.6. RuCl2(3-cyclohexyl-1-indenylidene) (PCy3)2, 7c
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3
3JH,H ¼ 7.3 Hz, 1H, H-7), 7.29 (t, JH,H ¼ 7.3 Hz, 1H, H-5), 7.19 (t,
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ꢀ
1.37e1.52, 1.15e1.24; 13C{1H}NMR (126 MHz, CDCl3, 20 ꢀC):
d 298.0
(t, 2JC,P ¼ 7.6 Hz, C-1),147.3 (C-3),143.6 (C-8),141.5 (C-9),137.4 (C-2),
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CDCl3, 20 ꢀC):
d
31.5 (s). IR (Neat):
n
¼ 2930, 2854, 1547, 1446, 1346,
1328,1301, 1295, 1270,1230, 1205, 1198, 1175, 1130, 1110,1077, 1020,
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