Synthesis and structure of [Ru(dppe)2(CH3CN)Cl] [BPh4] and its catalytic application to anti-Markovnikov addition of carboxylic acids to terminal alkynes

Article abstract of DOI:10.1016/j.jorganchem.2011.11.017

The compound, [Ru(dppe)₂(CH₃CN)Cl][BPh₄] (1) has been synthesized from the precursor complex, [(PPh₃) ₂Ru(CH₃CN)₃Cl][BPh₄]. The complex has been structurally character

Full text of DOI:10.1016/j.jorganchem.2011.11.017

Journal of Organometallic Chemistry 700 (2012) 78e82
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and structure of [Ru(dppe)2(CH3CN)Cl][BPh4] and its catalytic
application to anti-Markovnikov addition of carboxylic acids to terminal alkynes
*
Uttam Kumar Das, Manish Bhattacharjee
Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The compound, [Ru(dppe)2(CH3CN)Cl][BPh4] (1) has been synthesized from the precursor complex,
[(PPh3)2Ru(CH3CN)3Cl][BPh4]. The complex has been structurally characterized. This complex has been
found to be an efficient catalyst for the anti-Markovnikov addition of carboxylic acids to alkynes.
Ó 2011 Elsevier B.V. All rights reserved.
Received 6 September 2011
Received in revised form
9 November 2011
Accepted 15 November 2011
Keywords:
Ruthenium
Alkyne
Carboxylic acid
Addition of carboxylic acid to alkyne
Catalysis
1. Introduction
cis-[Ru(dppe)2(CH3CN)Cl]PF6 has not been structurally character-
ized and their catalytic properties still remains unexplored.
Coordinatively unsaturated ruthenium complexes have received
much attention due to their involvement in transition metal cata-
lyzed organic transformations. Ruthenium can adopt wide range of
coordination geometry and oxidation states and because of this
ruthenium compounds are found to be effective catalysts for
variety of organic reactions [1e3]. It has been emphasized in the
literature that, 16 electron cationic species are the active catalyst in
many cases. Thus, in recent years, some 16 electron cationic stable
species have been isolated and characterized structurally [4e6].
Ruthenium(II) phosphine complexes are widely used as catalyst for
various types of organic transformations. A large number reports
deal with synthesis of ruthenium complexes of tertiary phosphines
of all types, including bi and tridentate phosphines [7e15]. For
example, diphenylphosphinoethane complex of ruthenium of the
type, [Ru(dppe)2Cl2] has been synthesized from the reaction of
RuCl2(DMSO)4 with the diphosphine ligand [16]. However, reaction
of RuCl2(DMSO)4 with the diphenylphosphinoethane affords
mixture of cis- and trans- isomers [16]. The corresponding cationic
complexes of the type, and [Ru(dppe)2Cl]PF6 and cis-[Ru(dp-
pe)2(CH3CN)Cl]PF6 have been synthesized from the parent
complex, cis-[Ru(dppe)2Cl2] [17]. It is worth mentioning here that,
Ruthenium complexes with diphosphine ligands have been
shown to be effective catalysts for various organic transformations
[18e20]. Control of stereo and regioselectivity of metal catalyzed
organic transformations has been shown to be dependent on the
ligand environment around the metal center. Thus, ligand
controlled metal catalysis has received much attention in recent
years [21e24].
Rotem and Shvo reported the first ruthenium catalyzed addition
of carboxylic acid to alkyne using Ru3(CO)12 as catalyst [25,26],
which was followed by a large number of reports on ruthenium
catalyzed addition of carboxylic acid to alkynes [27e36]. Addition
of carboxylic acid to alkynes affords three possible isomers
(Scheme 1) and most of the reported reactions afford more than
one isomers. Ruthenium catalyzed addition of carboxylic acid has
been studied extensively by Dixneuf and coworkers [27,32,33] and
Mitsudo and coworkers [29e31] and catalytic systems for anti-
Markovnikov addition as well as Markovnikov addition product
have been developed. For anti-Markovnikov addition, the catalysts
used were synthesized from sensitive organometallic compounds
like, bis(cyclootadienyl)Ru [29,30] or bis(2-methylpropenyl)-
(cyclooctadienyl)Ru [27]. Recently Goossen et al. have reported
anti-Markovnikov addition of carboxylic acid to alkynes using [(p-
cumene)RuCl2]2 and phosphenes like PPh3, P(Fur)3, or P(p-Cl-
C6H4)3 in the presence of organic bases like pyridine or (4-
dimethylamino)pyridine [28]. We have been interested in the
* Corresponding author. Tel.: þ91 3222 283302; fax: þ91 3222 282252.
E-mail addresses: mxb@chem.iitkgp.ernet.in, mxb@iitkgp.ac.in (M. Bhattacharjee).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.11.017

U.K. Das, M. Bhattacharjee / Journal of Organometallic Chemistry 700 (2012) 78e82
79
expected to form a vinylidene complex on reaction with terminal
alkynes. The carboxylic acid is expected to attack the C2 carbon of
the vinylidene moiety, leading to the formation of anti-Markovni-
kov addition product. Herein we report synthesis, structure and
catalytic properties of the cationic ruthenium complex, [Ru(dp-
pe)2(CH3CN)Cl][BPh4] (1).
Scheme 1. Three possible products of the reaction of alkyne with carboxylic acid.
Table 1
Crystal data and structure refinement for 1.
2. Results and discussion
Empirical formula, Formula weight
Temperature, K
Wavelength (Å)
C78H71BClNP4Ru, 1293.57
293(2)
0.71073
2.1. Synthesis and characterization
Crystal system, Space group
a (Å), b (Å), c (Å)
Triclinic, P-1
12.3230(13), 13.8160(14), 19.274(2)
93.776(3), 97.575(3), 94.302(3)
3234.1(6)
2
1.328
0.428
1344
1.07e27.40
The complex has been synthesized from the reaction of
[(PPh3)2Ru(CH3CN)3Cl][BPh4] with diphenylphosphinoethane
(dppe) in 1:1 ratio in acetonitrile. The complex has been charac-
terized by elemental analyses, IR, and 1H and 31P NMR
spectroscopy.
a
,
b
,
g
(ꢂ)
V (Å3)
Z
Dcalc. (Mg/m3)
m
(Mo-K
F(000)
range (ꢂ)
a
) (mmꢁ1
)
The elemental analyses agree well with the formulation of the
compound. The 1H NMR spectrum of the compound in CDCl3
solution shows a broad signal at 2.70 ppm due to the four eCH2
protons of the bonded dppe ligand and eCH3 protons of the coor-
dinated acetonitrile ligand, which is in good agreement with other
ruthenium dppe complexes [16,17]. The signals for the aromatic
protons appear as multiplets in the region 6.56e7.88 ppm. Along
with these signals a singlet appears at 2.07 ppm. This is due to the
eCH3 protons of free acetonitrile. The appearance of the signal for
free acetonitrile clearly shows that, the complex undergoes disso-
ciation and produces a five coordinate species in solution. At ꢁ40 ꢂC
the signal at 2.70 ppm splits into two broad signals, which appear at
2.75 and 2.65 ppm. The signal for free acetonitrile ligand appears at
2.07 ppm. Thus it is clear that, even at low temperature the
complex undergoes dissociation in solution to give a five coordinate
species. The 31P NMR spectrum of the complex in CDCl3 solution
shows a sharp singlet at 48.7 ppm.
q
Reflections collected, Unique reflections 43,614, 14,108
R(int)
0.0727
0, 776
0.991
Restraints, parameters
Goodness of fit (F2)
Final R indices [I > 2
R indices (all data)
s
(I)]
R1 ¼ 0.0530, wR2 ¼ 0.1109
R1 ¼ 0.1236, wR2 ¼ 0.1440
synthesis of simple catalytically active ruthenium(II) cationic
compound containing phosphine ligands and labile N donor
ligands, which can easily afford 16 electron species in solution.
Recently, we have reported synthesis, structure and catalytic
properties of the cationic complex, [(PPh3)2Ru(CH3CN)3Cl][BPh4]
[37e40]. The cationic complex was found to be an active catalyst for
condensation of carboxylic acid and alkynes in the presence of
ꢀ
catalytic amount of BF3 Et2O [40]. The major product was found to
be Markovnikov addition product. Dixneuf and coworkers have
suggested that, for the anti-Markovnikov addition diphosphine
complexes are more efficient and also, it has been suggested that,
the addition takes place via external attack of carboxylic acid to the
electrophilically activated coordinated alkyne. We wanted to
synthesize a cationic ruthenium complex containing diphosphine
ligand having only one vacant coordination site. This complex is
2.2. Single crystal X-ray structure
The complex crystallizes in triclinic space group P-1 (Table 1).
The asymmetric unit contains one cationic ruthenium complex,
[Ru(dppe)2(CH3CN)Cl]þ, and one tetraphenylborate anion. The
Fig. 1. ORTEP view of [Ru(dppe)2(CH3CN)Cl]þ cation. Hydrogen atoms have been omitted for clarity.

80
U.K. Das, M. Bhattacharjee / Journal of Organometallic Chemistry 700 (2012) 78e82
Table 2
Important bond distances [Å] and bond angles [ꢂ] of 2 and 3.
Bond distances [Å]
Bond angles [ꢂ]
N(1)-Ru(1)
P(1)-Ru(1)
P(2)-Ru(1)
P(3)-Ru(1)
P(4)-Ru(1)
Cl(1)-Ru(1)
2.006(3)
N(1)-Ru(1)-P(2)
P(2)-Ru(1)-P(1)
P(2)-Ru(1)-P(4)
N(1)-Ru(1)-P(3)
P(1)-Ru(1)-P(3)
N(1)-Ru(1)-Cl(1)
P(1)-Ru(1)-Cl(1)
P(3)-Ru(1)-Cl(1)
92.59(10)
80.29(4)
N(1)-Ru(1)-P(1)
N(1)-Ru(1)-P(4)
P(1)-Ru(1)-P(4)
P(2)-Ru(1)-P(3)
P(4)-Ru(1)-P(3)
P(2)-Ru(1)-Cl(1)
P(4)-Ru(1)-Cl(1)
99.03(10)
89.68(10)
99.09(4)
98.22(4)
82.33(4)
88.20(4)
89.52(4)
2.3940(12)
2.3510(12)
2.4106(11)
2.3964(12)
2.4241(10)
177.71(4)
82.58(10)
177.83(4)
178.02(10)
79.31(4)
99.11(4)
cationic complex has a ruthenium(II) center bonded to one aceto-
nitrile and a chloride in a trans fashion and two diphenylphosphi-
noethane ligands in cis fashion (Fig. 1). The BPhꢁ4 anion is found
outside the coordination sphere and does not show any bonding
interaction with ruthenium(II) center. All the four Ru-P distance
are not equal [P1eRu1 ¼ 2.3940(12) Å, P2eRu1 ¼2.3510(12) Å,
P3eRu1 ¼2.4106(11) Å, P4eRu1 ¼ 2.3964(12) Å]. The :N1-Ru1-
Cl1 angle is less then 180ꢂ [178.02(10)]. Similarly, the :P(1)-
Ru(1)-P(3) and :P(2)-Ru(1)-P(4) angles are found to be 177.83(4)ꢂ
and 177.71(4)ꢂ, respectively (Table 2). Thus, the ruthenium(II)
center is found to be in a distorted octahedral coordination
environment.
NMR spectroscopy. In addition, the newly synthesized compounds,
4e, 4h, 4k and 4l have been characterized by high resolution mass
spectrometry (HRMS).
In contrast to the [(PPh3)2Ru(CH3CN)3Cl][BPh4] catalyzed addi-
tion of carboxylic acids to terminal alkynes, which afford Markov-
nikov addition product [40], in the present catalytic system, the
major product is anti-Markovnikov addition product. Also, in
[(PPh3)2Ru(CH3CN)3Cl][BPh4] catalyzed reaction addition of Lewis
acid, BF3 is necessary. However, in the present case, addition of
Lewis acid is not required. No improvement on the conversion
could be observed upon addition of BF3Et2O. Apart from these, the
turnover numbers were found to be slightly better compared to the
[(PPh3)2Ru(CH3CN)3Cl][BPh4] catalyzed reaction. In the complex,
[(PPh3)2Ru(CH3CN)3Cl][BPh4] the number of possible vacant coor-
dination sites is more, as a result we could observe coordination of
both the substrates to the ruthenium center [40]. However, the
number of possible vacant coordination site in [Ru(dppe)2(CH3CN)
Cl][BPh4] is only one and thus, in the in situ NMR studies (vide infra)
2.3. Catalytic addition of carboxylic acids to alkynes
We were interested in studying the efficacy of 1 as catalyst for
the addition of carboxylic acids to alkynes. The reaction of phe-
nylacetylene with benzoic acid in toluene was chosen as a model
reaction to establish the reaction condition. Benzoic acid (5 mmol)
was mixed with phenylacetylene (5 mmol) and 1 (0.05 mmol) in
toluene (5 cm3) and the reaction was monitored by HPLC. To begin
with the reaction was carried out for 12 h at room temperature.
However, we could not detect any product formation. Gradually the
temperature was raised to 70 ꢂC, but even at that temperature no
reaction took place. However, at 90 ꢂC we could observe product
formation and at 12 h complete conversion was achieved. The
product obtained was a mixture of E and Z isomers (25:75) of anti-
Markovnikov product (60%) and Markovnikov addition product
(40%) (Table 3). When the temperature was raised to 110 ꢂC, the
regioselectivity of the addition reaction changed and a mixture
(5:95) of Markovnikov and anti-Markovnikov addition product was
obtained. The ratio of the E and Z isomers of the anti-Markovnikov
product was found to be 20:80.
Scheme 2. Reaction of various alkynes with different carboxylic acids catalyzed by 1.
Having established the reaction condition, the scope of the
reaction was tested. The reactions of various alkynes with
aromatic and aliphatic carboxylic acids were carried out (Scheme
2, Table 4). The reaction was found to be effective in the cases of
both aromatic and aliphatic carboxylic acids as well as alkynes.
The products were isolated in 80e90% yield with moderate
turnover number. The products were characterized by 1H and 13C
Table 4
Reaction of alkynes with carboxylic acid catalyzed by 1.a
Entry
Alkyne
Acid
Product
Yield (%)b
E/Z
TONC
1
2
3
4
5
6
7
8
2a
2a
2a
2a
2a
2a
2a
2a
2b
2b
2c
2c
3a
3b
3c
3d
3e
3f
3g
3h
3d
3e
3d
3c
4a
4b
4c
4d
4e
4f
4g
4h
4i
90
85
87
95
10/90
20/80
20/80
20/80
25/75
35/65
15/85
5/95
25/75
20/80
25/75
35/65
180
170
174
190
160
170
164
150
160
170
166
160
80d
85d
82d
75e
80
Table 3
Temperature dependence of the product distribution of 1 catalyzed reaction of
phenylacetylene and benzoic acid acid.a
9
T (ꢂC)
Yield (%)
Yield (%) (Anti-Markovnikov)b
(E/Z)c
10
11
12
4j
4k
4l
85d
83
80
Entry
(Markovnikov)b
1
2
90
110
40
5
60 (25:75)
95 (20:80)
a
Reaction condition: 2 mmol carboxylic acid, 2 mmol alkyne in 5 cm3 of toluene
and 0.01 mmol of catalyst, time 12 h.
a
Reaction condition: 5 mmol benzoic acid, 5 mmol phenylacetylene in 5 cm3 of
b
Isolated.
mol of product/mol of catalyst.
Time 15 h.
toluene and 0.05 mmol of catalyst, time 12 h.
c
b
Isolated.
d
c
HPLC and 1H NMR.
e
Time 17 h.

U.K. Das, M. Bhattacharjee / Journal of Organometallic Chemistry 700 (2012) 78e82
81
Scheme 3. Plausible mechanism of reaction of alkyne and carboxylic acid catalyzed by 1.
we could observe only coordination of alkyne. This may be the
3. Conclusion
reason for difference in regioselectivity of the addition reaction.
In summary, we have synthesized a simple cationic ruthenium
complex, [Ru(dppe)2(CH3CN)Cl][BPh4], using commercially avail-
able cheap chemicals. The complex is not air or moisture sensitive.
This complex can catalyze anti-Markovnikov addition of carboxylic
acids to alkynes, in a stereoselective manner affording Z-vinyl
esters. The catalyst loading is low (0.5 mol%) and the reaction does
not require any harmful additives like pyridine.
2.4. Mechanistic investigations
We have carried out in situ 31P as well as 1H NMR spectral
studies in order to get an insight into the mechanism of the reac-
tion. As discussed earlier, the 1H NMR spectrum of the complex
clearly show that, in solution, it affords a pentacoordinated ruthe-
nium complex cation, [Ru(dppe)2Cl]þ.
4. Experimental
The31PNMRspectrumofthecomplexintoluene-d8 shows a singlet
at 49.1 ppm. The spectrum remains unchanged when the solution is
heated up to 110 ꢂC. However, when phenylacetylene is added to the
solution and is heated to 110 ꢂC, a new intense signal appears at
38.1 ppm. The 1H NMR spectrum of this solution shows a new signal at
3.40 ppm (singlet). This can be assigned to the ruthenium coordinated
vinylidene proton of the species, [Ru(]C]CHPh)(dppe)2Cl]þ. This
assignment is in good agreement with a structurally characterized
Chemicals and solvents used were reagent grade products. The
1H, 13C and 31P NMR spectra were recorded on Bruker Avance II (1H
frequency ¼ 400 MHz and 200 MHz) spectrometers. HRMS of the
newly synthesized compounds, 4e, 4h, 4k and 4l were recorded on
TOF MS in ESIþ mode in methanol water mixture.
4.1. Preparation of [Ru(dppe)2(CH3CN)Cl][BPh4] (1)
ruthenium vinylidene compound, [(p-Cymene)Ru(m-Cl)3RuCl(]C]
CHPh)(IMes)] {IMes ¼ 1,3-dime-setylimidazole-2-yilidene}, the 1H
NMR spectrum of which shows a singlet at 3.41 ppm due to the
vinylidene proton [41]. It may be noted that, a similar ruthenium
vinylidene intermediate has been suggested in the ruthenium cata-
lyzed synthesis of vinylic carbamates by the reaction of secondary
amines, CO2 and terminal alkynes [27].
To the solution of the complex and phenylacetylene, when
acetic acid is added and heated, a new signal (singlet) appears at
2.28 ppm in the 1H NMR spectrum. This singlet can be assigned
to the eCH3 protons of the ester group. Based on the above in
situ NMR studies a plausible mechanism has been suggested,
which has been shown in Scheme 3. The first step is the coor-
dination of alkyne to [Ru(dppe)2Cl]þ (A) followed by the rear-
rangement of the coordinated alkyne to give alkylidene species,
[Ru(]C]CHPh)(dppe)2Cl]þ (B). This is followed by the external
attack by the carboxylic acid to produce the species C, which is
followed by the release of the product by protonolysis
(Scheme 3).
A sample of [(PPh3)2Ru(CH3CN)3Cl][BPh4] (1.1 g; 1 mmol) and
dppe (0.76 g; 2 mmol) was dissolved in acetonitrile (10 cm3) and
the reaction solution was refluxed for about 2.5 h. The reaction
solution was then filtered. The filtrate was concentrated on water-
bath, where upon a yellow crystalline solid separated out. The
separated solid was filtered and washed with hexane (3e4 times)
and dried in vacuo. The compound was finally recrystallized from
acetonitrile. Yield: 1.02 g; 79%. Anal. Calc. for C78H71BClNP4Ru (Mol.
Wt. ¼1293.63): C; 72.42, H; 5.53, N; 1.08. Found: C; 71.08, H; 4.72,
N; 0.98. IR (cmꢁ1): 730, 745, 930, 1434, 1483, 3053. 1H NMR (CDCl3)
(in ppm): 2.70 (br, 11H) 6.55e7.82 (m, 60H). 31P NMR (CDCl3) (in
ppm): 48.7.
4.2. [Ru(dppe)2(CH3CN)Cl][BPh4] (1) catalyzed reaction of alkynes
with carboxylic acid
The alkyne (2 mmol), acid (2 mmol), and the catalyst
(0.01 mmol) were taken in 5 cm3 toluene in a 25 ml round

82
U.K. Das, M. Bhattacharjee / Journal of Organometallic Chemistry 700 (2012) 78e82
[5] C. Gemel, K. Mereiter, R. Schmid, K. Krichner, Organometallics 16 (1997)
5601e5603.
[6] Y. Yamagichi, H. Nagashima, Organometallics 19 (2000) 725e727.
[7] M.J. Burn, M.G. Fickes, F.J. Hollander, R.G. Bergman, Organometallics 14 (1995)
137e150.
[8] E. Fache, C. Santini, F. Senocq, J.M. Basset, J. Mol. Catal. 72 (3) (1992) 331e336.
[9] P.S. Hallman, T.A. Stephenson, G. Wilkinson, Inorg. Synth. 12 (1970) 237e240.
[10] P.S. Hallman, B.R. McGarvey, G. Wilkinson, J. Chem. Soc. A (1968) 3143e3150.
[11] L.D. Field, A.V. George, D.C.R. Hockless, G.R. Purches, A.H. White, J. Chem. Soc
Dalton Trans. (1996) 2011e2016.
[12] J. Chatt, R.G. Hayter, J. Chem. Soc. (1961) 896e904.
[13] J. Chatt, R.G. Hayter, J. Chem. Soc. (1961) 2605e2611.
[14] L.D. Field, T.W. Hambley, B.C.K. Yau, Inorg. Chem. 33 (1994) 2009e2017.
[15] M.E. Woodhouse, F.D. Lewis, T.J. Marks, J. Am. Chem. Soc. 104 (1982)
5586e5594.
[16] M.T. Bautista, E.P. Cappellan, S.D. Drouin, R.H. Morris, C.T. Schweitzer, A. Sella,
J. Zubkowski, J. Am. Chem. Soc. 113 (1991) 4876e4887.
[17] B. Chin, A.J. Lough, R.H. Morris, C.T. Schweitzer, C. D’Agostino, Inorg. Chem. 33
(1994) 6278e6288.
[18] O. Kröcher, R.A. Köppel, A. Baiker, Chem. Commun. (1997) 453e454.
[19] J.A. van Rijn, M. Lutz, L.S. von Chrzanowski, A.L. Spek, E. Bouwman, E. Drent,
Adv. Synth. Catal. 351 (2009) 1637e1647.
[20] P.W.N.M. van Leeuwen, P.C.J. Kamer, J.N.H. Reek, P. Dierkes, Chem. Rev. 100
(2000) 2741e2770.
[21] D.J. Gorin, B.D. Sherry, F.D. Toste, Chem. Rev. 108 (2008) 3351e3378.
[22] R. Kumareswaran, M. Nandi, T.V. RajanBabu, Org. Lett. 5 (2003) 4345e4348.
[23] D. Zhao, K. Oisaki, M. Kanai, M. Shibasaki, J. Am. Chem. Soc. 118 (2006)
14440e14441.
bottomed flask fitted with a reflux condenser. The reaction mixture
was stirred for desired time (12e17 h) at 110 ꢂC. The reactions were
monitored by TLC. After the completion of the reaction, the solvent
was removed under vacuum. The products were purified by column
chromatography. The products were characterized by 1H and 13C
NMR spectroscopy. The new compounds, 4e, 4h, 4k and 4l, have
been further characterized by HRMS. The spectral data and the
spectra are given in supplementary material.
4.3. Single crystal data collection and refinements
Single crystal X-ray data of 1 were collected on Bruker Smart
APEX system that uses graphite monochromated Mo-Ka radiation
(
l
¼ 0.71073 Å). The structure was solved by direct method and
refined by least square method on F2 employing WinGx [42]
package and the relevant programs (SHELX-97 [43] and ORTEP-3
[44]) implemented therein. Non-hydrogen atoms were refined
anisotropically and hydrogen atoms on C-atoms were fixed at
calculated positions and refined using a riding model. The crystal
data is given in Table 1 and important bond distances and bond
angles are given in Table 2.
[24] H. Doucet, V.B. Martin, C. Bruneau, P.H. Dixneuf, J. Organomet. Chem. 60
(1995) 7247e7255.
Acknowledgment
[25] M. Rotem, Y. Shvo, Organometallics 2 (1983) 1689e1691.
[26] M. Rotem, Y. Shvo, J. Organomet. Chem. 448 (1993) 189e204.
[27] C. Bruneau, P.H. Dixneuf, Chem. Commun. (1997) 507e512.
[28] L.J. Goossen, J. Paetzold, D. Koley, Chem. Commun. (2003) 706e707.
[29] T. Mitsudo, Y. Hori, Y. Watanabe, J. Organomet. Chem. 50 (1985) 1566e1568.
[30] T. Mitsudo, Y. Hori, Y. Yamakawa, Y. Watanabe, Tetrahedron Lett. 27 (1986)
2125e2126.
We thank Department of Science & Technology, Government of
India, New Delhi for single crystal X-ray and NMR facilities. UKD
thanks Council of Scientific & Industrial Research, New Delhi for
fellowship.
[31] T. Mitsudo, Y. Hori, Y. Yamakawa, Y. Watanabe, J. Organomet. Chem. 52 (1987)
2230e2239.
Appendix. Supplementary material
[32] C. Ruppin, P.H. Dixneuf, Tetrahedron Lett. 27 (1986) 6323e6324.
[33] M. Neveux, B. Seiller, F. Hagedorn, C. Bruneau, P.H. Dixneuf, J. Organomet.
Chem. 451 (1993) 133e138.
[34] N.E. Leadbeater, K.A. Scott, L.J. Scott, J. Organomet. Chem. 65 (2000)
3231e3232.
Supplementary data related to this article can be found online at
doi:10.1016/j.jorganchem.2011.11.017.
[35] S. Ye, W.K. Leong, J. Organomet. Chem. 691 (2006) 1117e1120.
[36] K. Melis, P. Samulkiewicz, J. Rynkowski, F. Verpoort, Tetrahedron Lett. 43
(2002) 2713e2716.
References
[37] S. Naskar, M. Bhattacharjee, J. Organomet. Chem. 690 (2005) 5006e5010.
[38] S. Naskar, M. Bhattacharjee, Tetrahedron Lett. 48 (2007) 465e468.
[39] S. Naskar, M. Bhattacharjee, Tetrahedron Lett. 48 (2007) 3367e3370.
[40] J. Tripathy, M. Bhattacharjee, Tetrahedron Lett. 50 (2009) 4863e4865.
[41] Y. Borguet, X. Sauvage, G. Zaragoza, A. Domonceau, L. Delaude, Organome-
tallics 30 (2011) 2730e2738.
[42] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837e838.
[43] G.M. Sheldrick, Acta Crystallogr. A64 (2008) 112e122.
[44] L.J. Farrugia, J. Appl. Crystallogr. 30 (1997) 565.
[1] T. Naota, H. Takaya, S.-I. Murahashi, Chem. Rev. 98 (1998) 2599e2660 and
references therein.
[2] B.M. Trost, F.D. Toste, A.B. Pinkerton, Chem. Rev. 110 (2001) 2067e2096 and
references therein.
[3] G.C. Vougioukalakis, R.H. Grubbs, Chem. Rev. 98 (2010) 1747e1787 and
references therein.
[4] M.J. Tenorio, K. Mereiter, M.C. Pureta, P. Valerga, J. Am. Chem. Soc. 122 (2000)
11230e11231.