Syntheses and structures of ruthenium(II) N,S-heterocyclic carbene diphosphine complexes and their catalytic activity towards transfer hydrogenation

Article abstract of DOI:10.1002/asia.201000930

Phosphine exchange of [Ru^IIBr(MeCOO)(PPh₃) ₂(3-RBzTh)] (3-RBzTh=3-benzylbenzothiazol-2-ylidene) with a series of diphosphines (bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino) ethylene (dppv), 1,1′-bis(diph

Full text of DOI:10.1002/asia.201000930

DOI: 10.1002/asia.201000930
Syntheses and Structures of Ruthenium(II) N,S-Heterocyclic Carbene
Diphosphine Complexes and their Catalytic Activity towards Transfer
Hydrogenation
[
a]
[a, b]
Nini Ding and T. S. Andy Hor*
Abstract: Phosphine exchange of
N,S-heterocyclic carbene (NSHC), and
a bromide. Two geometric isomers of 6
(6a and 6b) have been isolated. The
structures of these products, which
have been elucidated by single-crystal
X-ray crystallography, show two struc-
tural types, I and II, depending on the
relative dispositions of the ligands.
Type I structures contain a carbenic
carbon atom trans to the oxygen atom,
whereas two phosphorus atoms are
trans to bromine and oxygen atoms.
The type II system comprises a carbene
II
[
(
Ru Br
3-RBzTh=3-benzylbenzothiazol-2-yli-
dene) with a series of diphosphines
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(MeCOO)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(PPh )
ACHTUNGERTNNUNG( 3-RBzTh)]
carbon atom trans to one of the phos-
phorus atoms, whereas the other phos-
phorus is trans to the oxygen atom,
with the bromine trans to the remain-
ing oxygen atom. Complexes 2, 3, 4,
and 6a belong to type I, whereas 5 and
6b are of type II. The kinetic product
6b eventually converts into 6a upon
standing. These complexes are active
towards catalytic reduction of para-
methyl acetophenone by 2-propanol at
828C under 1% catalyst load giving
the corresponding alcohols. The dppm
complex 2 shows the good yields (91–
97%) towards selected ketones.
3
2
(
(
bis(diphenylphosphino)methane
dppm), 1,2-bis(diphenylphosphino)-
ethylene (dppv), 1,1’-bis(diphenylphos-
phino)ferrocene (dppf), 1,4-bis(diphe-
nylphosphino)butane (dppb), and 1,3-
(
diphenylphosphino)propane (dppp))
gave mononuclear and neutral octahe-
2
dral complexes [RuBr
ACTHUNGTNERNUNG( MeCOO) ACHTUNGRTENNUNG( h -
P )(3-RBzTh)] (P =dppm (2), dppv
ACHTUNGTRENNUNG
2
2
(
3), dppf (4), dppb (5), or dppp (6)),
Keywords: carbenes · diphosphines ·
the coordination spheres of which con-
tained four different ligands, namely, a
chelating diphosphine, carboxylate,
N,S-heterocycles
·
ruthenium
·
transfer hydrogenation
[
3]
Introduction
bene. Prominent examples include the second-generation
Grubbs olefin metathesis catalysts that contain coordinated
[4]
[5]
Catalytic reactions utilizing ruthenium N-heterocyclic car-
bene (NHC) complexes have witnessed an explosive growth
tricyclohexylphosphine (PCy ). Chelating alkylidenes, bi-
3
dentate Schiff base ligands, heterodonating P,O- and N,O-
chelates etc. have been introduced to improve the thermal,
[6]
[1,2]
[7]
in the last two decades.
These species are generally
robust and tolerant towards many functional groups under
standard organic synthetic conditions. One of the general
design principles of active ruthenium–NHC complexes re-
quires the disposition of a labile functionality trans to car-
oxygen, and moisture tolerance. Somewhat surprising is the
lack of bidentate phosphine ligands among the known ruthe-
[8]
nium–NHC catalysts,
complexes have been proven to be effective towards a wide
although ruthenium diphosphine
[9]
range of organic transformations. It is hence desirable to
develop a facile synthetic methodology for ruthenium(II)
NHC–diphosphine complexes for catalysis. In view of the
demonstrated application of N,S-heterocyclic carbene
[
a] N. Ding, Prof. T. S. A. Hor
Department of Chemistry
National University of Singapore
[10]
3
Science Drive 3, 117543 (Singapore)
(NSHC) in olefin metathesis, and as part of our ongoing
[11]
Fax : (+65)68731324
E-mail: andyhor@nus.edu.sg
effort in NSHC research, we herein report a general syn-
II
thetic pathway for mixed-ligand complexes [Ru Br-
[
b] Prof. T. S. A. Hor
2
A
H
U
G
R
N
N
(MeCOO)
A
H
U
G
R
N
U
G
A
H
U
T
E
N
N
(3-RBzTh)] (3-RBzTh=3-benzylbenzothia-
2
Institute of Materials Research and Engineering
Agency for Science, Technology and Research
zol-2-ylidene; P =diphosphine). Their structural character-
2
istics and catalytic activities towards transfer hydrogenation
are described and discussed.
3
Research Link, S117602 (Singapore)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201000930.
Chem. Asian J. 2011, 6, 1485 – 1491
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1485

FULL PAPERS
Results and Discussion
phosphorus trans to carbene and oxygen atoms, respective-
ly). Under tetrahydrofuran reflux conditions, 6a is formed
and isolated in pure form. Complex 6b is formed at room
Synthesis and Characterization of Complexes 2–6
II
31
Diphosphine substitutions of [Ru Br
A
H
U
G
E
N
N
(MeCOO)
A
H
U
G
R
N
U
G
2A
H
U
G
R
N
N
(3-
temperature but cannot be isolated free of 6a. Its P NMR
3
[11j]
RBzTh)] (1),
which can be easily prepared from [Ru-
resonances are fluxional, probably through an interconvert-
ing process of diastereomeric isomers in solution. Upon
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(MeCOO) (PPh ) ], by bis(diphenylphosphino)methane
ACHTUNGTRENNUNG
2
3 2
31
(
dppm), 1,2-bis(diphenylphosphino)ethylene (dppv), 1,1’-
bis(diphenylphosphino)ferrocene (dppf), 1,4-bis(diphenyl-
phosphino)butane (dppb), and 1,3-(diphenylphosphino)pro-
cooling from room temperature to ꢀ208C, the broad P res-
onance sharpens and is then well-resolved into a pair of an-
2
ticipated doublets ( J =40 Hz; see the Supporting Informa-
PP
pane (dppp) give new complexes [RuBr
A
H
U
G
R
N
U
G
tion, Figure S1). Its solution slowly changes from red to
3
1
RBzTh)] (P =dppm (2), dppv (3), dppf (4), dppb (5), or
dppp (6)) in moderate to high yields (61–95%; Scheme 1).
bright yellow at room temperature. Its P NMR spectrum
2
3
1
accordingly suggests the conversion of 6b ( P NMR spectra:
d=54.2 and 14.6 ppm) into 6a
3
1
(
P NMR spectra: d=45.7 and
0.5 ppm) within 66 hours at
4
room temperature (see the Sup-
porting Information, Figure S2)
Complex 6b is hence concluded
to be a kinetic product in a re-
action that drives towards 6a as
the thermodynamic outcome.
Complexes 2–6 (except 6b) are
stable in both solid and solution
states.
Molecular Structures of
Complexes 2–6
Scheme 1. Synthetic route to ruthenium(II)–benzothiazol-2-ylidene complexes 2–6.
All the complexes have been
crystallized and their structures unequivocally elucidated by
single-crystal X-ray diffraction studies (Figure 1). They are
universally mononuclear and neutral, showing an octahedral
ruthenium sphere with four different ligands, namely, a che-
lating diphosphine, carboxylate, NSHC carbene, and bro-
mide. They can be categorized into two structural types, I
and II, based on the relative dispositions of the ligands.
Type I structures contain a carbenic carbon trans to the
oxygen atom, whereas two phosphorus atoms are trans to
the bromine and oxygen atoms. The type II system compris-
es a carbene carbon atom trans to one of the phosphorus
atoms, whereas the other phosphorus atoms is trans to
oxygen, with bromine trans to the remaining oxygen atom.
Complexes 2, 3, 4, and 6a belong to type I, whereas 5 and
6b are type II structures (Scheme 1). The former, with the
phosphine group avoiding facing a high trans-ligand carbene,
is more common and generally expected. Although 5 shares
the same structural type as 6b, it is thermodynamically
stable and does not convert into the type I isomer under the
present experimental conditions.
They are readily soluble in dichloromethane, tetrahydrofur-
an, and toluene and slightly soluble in diethyl ether. They
can also be prepared from phosphine substitution directly
with the precursor, namely [Ru ACTHUNGTERNNN(UG MeCOO) CAHTUNGRTENNGU( PPh ) ], giving
2 3 2
2
[12]
[Ru
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(MeCOO)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -P )],
followed by acid condensation
2
2
with a benzothiazolium salt. This alternative synthesis is ex-
emplified by the successful preparation of 2 and 5 from the
2
one-pot condensation reaction between [Ru
A
H
U
G
R
N
U
G
A
H
U
G
E
N
N
(h -
2
P )] and N-benzylbenzothiazolium
2
bromide
[
(C H )SCHNR]X (R and X=benzyl and Br) in the pres-
6 4
ence of NaOAc.
All products have been characterized by ESI spectral
31
analysis. Their P NMR spectra show downfield shifts, thus
pointing to successful coordination of both phosphine sites
in all cases. The most notable contrast with 1 is the presence
31
of two discrete P NMR resonances, implying cis orienta-
tion of a chelating diphosphine with different trans ligands
across the phosphine donors. This rules out a symmetrical
bridge formation or a trans orientation as occurred in 1. The
phosphine inequivalence and restricted rotation of the Ruꢀ
C bond differentiate the two CH protons of the benzyl sub-
The heterocylic ring of the carbene tends to rotate out of
the coordination plane (by 18.8–42.18 in 2–6) to accommo-
date other secondary intra- and intermolecular interactions
(see the Supporting Information, Figure S3). In 2, the rota-
tion (28.48) is accompanied by intramolecular CꢀH···O hy-
drogen bonding (C8···O1: 3.03 ꢁ; C8ꢀH8B···O1: 138.98) and
2
stituent.
31
The P NMR spectrum of the reaction mixture of 1 and
dppp at room temperature is unique in showing a mixture of
products that are consistent with geometric isomers 6a and
6
b. Both show mutually coupled inequivalent phosphines
6a: d=40.5 and 45.7 ppm for the phosphorus donors trans
to bromide and oxygen atoms; 6b: d=14.6 and 54.2 ppm for
(
intermolecular offset p–p interactions (3.35 ꢁ) between the
heterocyclic ring and its symmetry-generated counterpart
1486
www.chemasianj.org
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2011, 6, 1485 – 1491

Ruthenium(II) N,S-Heterocyclic Carbene Diphosphine Complexes
(
ꢀx, ꢀy+1, ꢀz+1; see the Supporting Information). In 3,
similar CꢀH···O hydrogen bonding (C8···O2: 3.03 ꢁ; C8ꢀ
H8B···O2: 135.18) is evident except that the rotation increas-
es to 31.98 to alleviate the close contacts between the g-H
on the nitrogen substituent and the protons on the neighbor-
ing phenyl rings of dppv (H8A···H2C: 2.84 ꢁ). In 4, the ro-
tation rises further to 32.38 to accommodate the CꢀH···O
hydrogen bonding (C8···O2: 3.03 ꢁ; C8ꢀH8A···O2: 141.68),
nonbonding H···H contact (H8B···H6B: 2.48 ꢁ), and addi-
tional intramolecular face-to-face p–p interactions between
the five-membered C1-S1-C7-C2-N1 and six-membered
C1B-C2B-C3B-C4B-C5B-C6B (3.45 ꢁ between ring cent-
roids) rings. In 5, the intramolecular CꢀH···O hydrogen
bonding (C8···O2: 2.89 ꢁ; C8ꢀH8B···O2: 121.18) and the in-
tramolecular face-to-face p–p interactions between the five-
membered C1-S1-C7-C2-N1 and six-membered C1C-C2C-
C3C-C4C-C5C-C6C (3.62 ꢁ between ring centroids) rings
possibly governs the carbene ring rotation (18.88). The large
ring rotation in 6a (42.18) is traced to an edge-to-face Cꢀ
H···p interaction between a pair of CꢀH bonds of the
phenyl ring of the nitrogen substituent and C=C bond of the
phenyl ring of dppp (H10···C6D: 2.92 ꢁ; C10ꢀH10···C6D:
1
53.18; H11···C5D: 3.32 ꢁ; C11ꢀH11···C5D: 129.98) and the
intramolecular CꢀH···O hydrogen bonding (C8···O2: 3.23 ꢁ;
C8ꢀH8A···O2: 135.68). Complex 6b shows intermolecular
hydrogen bonding within each pair of molecules. The ring
rotates 23.78 out of the coordination plane to minimize in-
teractions between the phenyl ring of the nitrogen substitu-
ent C13ꢀH13 or C14ꢀH14 and O2A (C13···O2A: 3.19 ꢁ;
C13ꢀH13A···O2A: 123.98; C14···O2A: 3.24 ꢁ; C14ꢀ
H14A···O2A: 118.28; symmetry code to generate O2A:
ꢀ
x+2, ꢀy+1, ꢀz+2).
It is remarkable that these diphosphines with a diverse
range of spacer lengths and skeletal properties have adapted
to a common mononuclear core as chelating ligands, espe-
[13a]
cially considering that ligands, such as dppf
and dppb,
could easily adopt the bridging mode. This feature is exem-
plified by the tolerance over a wide span of P-Ru-P angles
Figure 1. ORTEP of complexes 2–6 with 50% probability ellipsoids. All
hydrogen atoms and solvent molecules are omitted for clarity.
(
73.05(3)–101.16(7)8) and P···P distances (2.669–3.578 ꢁ;
Table 1). The metallo–diphosphine ring properties have
Table 1. Selected bond lengths [ꢁ] and angles [8] for complexes 2–6.
2
3
4
5
6a
6b
Ru(1)ꢀC(1)
1.972(3)
2.2311(9)
2.2529(9)
2.5792(5)
2.214(2)
2.186(2)
2.669
1.980(4)
2.245(1)
2.255(1)
2.5942( 6)
2.217(3)
2.205(3)
3.023
1.982(7)
2.335(2)
2.297(2)
2.570(1)
2.200(5)
2.200(5)
3.578
2.056(3)
2.3751(9)
2.2580(9)
2.5530(4)
2.226(2)
2.135(2)
3.429
1.957(7)
2.283(2)
2.280(2)
2.6025(9)
2.219(5)
2.182(5)
3.282
2.034(6)
2.363(2)
2.236(1)
2.5434(7)
2.127(4)
2.242(4)
3.322
Ru(1)ꢀP(1)
Ru(1)ꢀP(2)
Ru(1)ꢀBr(1)
Ru(1)ꢀO(1)
Ru(1)ꢀO(2)
P(1)···P(2)
P(1)-Ru(1)-P(2)
O(1)-Ru(1)-O(2)
C(1)-Ru(1)-P(1)
C(1)-Ru(1)-P(2)
Br(1)-Ru(1)-P(1)
Br(1)-Ru(1)-P(2)
73.05(3)
59.51(8)
95.75(9)
90.37(9)
98.53(3)
170.61(2)
28.4
84.38(4)
59.1(1)
93.3(1)
88.8(1)
95.71(3)
173.36(3)
31.9
101.16(7)
59.6(2)
89.7(2)
97.0(2)
169.52(5)
89.25(6)
32.3
95.46(3)
59.84(9)
174.77(9)
89.75(9)
90.76(2)
89.47(2)
18.8
92.00(7)
59.8(2)
93.8(2)
94.2(2)
89.86(5)
171.63(5)
42.1
92.45(5)
59.8(2)
173.6(2)
92.9(2)
85.95(4)
87.79(4)
23.7
[
a]
dihedral angle
[
a] Dihedral angle between the N,S-heterocyclic carbene ring and coordination plane.
Chem. Asian J. 2011, 6, 1485 – 1491
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
1487

N. Ding and T. S. A. Hor
FULL PAPERS
[
9,13]
been related to the catalytic behaviors of some systems.
cursor 1, which returns with a similarly yield of approxi-
mately 90% but requires a longer reaction duration.
Complex 2 was thus chosen to compare its effect on dif-
ferent alkyl and aryl ketones (Table 3). It returns with excel-
lent yields (91–97%) except towards benzophenone and 4-
methoxyacetophenone (Table 3, entry 5 and 6), which could
The RuꢀC bonds (1.957(7)–2.034(6) ꢁ) for 2–6 are within
the range reported for Ru–NSHC complexes (for example,
[11j]
complex 1 : 1.970(6) ꢁ); [RuCl (=CH-o-iPrO-Ph)(3-Ph-
2
[10]
DMeTh)]
.944(1) ꢁ), [Ru(CO)F(H)
tetramethylimidazol-2-ylidene;
(DMeTh=4,5-dimethylthiazol-2-ylidene;
[14]
1
ACHTUNGTNERNUNG( NHC) ACHTUGNTRENNUNG( PPh ) ] (NHC=1,3,4,5-
3 2
2.170(2) ꢁ),
(NHC=1,3-bis(2-diphenylphospha-
nylethyl)-3H-imidazol-2-ylidene; 2.038(3) ꢁ). With carbene
mer,cis-
[15]
[
RuCl (CO) ACHTUNGTRENNUNG( NHC)]
2
[
a]
Table 3. Catalytic transfer hydrogenation of ketones with complexes 2.
[16]
and phosphine at a mutually trans orientation,
type II
Entry Substrate
Product
Yield
%]
[
structures understandably show the longest, and presumably
weakest, RuꢀC (2.056(3) ꢁ for 5 and 2.034(6) ꢁ for 6b) and
RuꢀP bonds (2.3751(9) ꢁ for 5 and 2.363(2) ꢁ for 6b). The
1
2
3
4
5
cyclopentanone
acetophenone
4-chloroacetophenone
4-bromoacetophenone
4-methoxyacetophe-
none
cyclopentanol
1-phenylethanol
1-(4-chlorophenyl)ethanol
1-(4-bromophenyl)ethanol
1-(4-methoxyphenyl)etha-
nol
95
91
94
97
8
acetate chelate is most distorted in 6b, showing the highest
contrast in RuꢀO lengths (2.127(4) and 2.242(4) ꢁ), the
latter is also the weakest RuꢀO in this series. These offer a
6
benzophenone
diphenylmethanol
12
possible explanation on the fluxionality of 6b. A facile che-
late to monodentate conversion of the acetate would readily
create a fluxional 5-coordinated structure that would allow
the carbene and bromide to swap positions followed by che-
late reformation to give 6a. The stability of 6a is also exem-
[a] Experimental conditions: ketone (1 mmol), NaOtBu (0.1 mmol), cata-
lyst (0.01 mmol), 2-propanol (15 mL), T=828C.
plified by a near-ideal P1-Ru1-P2 chelate angle (92.00(7)8)
2
and strong J coupling (40.9 Hz).
be attributed to unfavorable electronic (Table 3, entry 5)
and steric effects (Table 3, entry 6) of the substituent on the
ketones. These are comparable with the performance of
PP
Transfer Hydrogenation
[11j]
[15–17]
1
.
Use of phosphine-free NHC complexes,
such as
The catalytic performance of 2–6 towards the reduction of
para-methyl acetophenone by 2-propanol to 1-(4-methylphe-
nyl)ethanol has been compared (Table 2). Complex 2 gener-
[RuCl (L)(NO)] (L=3-tert-butyl-1-(2-pyridyl)imidazol-2-yli-
3
dene) provides an alternative with similar yield (96%) in
similar reduction of acetophenone but within a shorter
period of 4 hours. There are other effective carbene-free cat-
alysts that are supported by [NNN] or [PNN] tridentate li-
[18,19]
gands.
Table 2. Catalytic transfer hydrogenation of para-methyl acetophenone
[
a]
with complexes 2–6.
Conclusions
We have developed a convenient synthetic method to ruthe-
nium(II) complexes with all-different ligands. The formula-
tion of these complexes are based on two stable and nondis-
sociative (namely, NSHC carbene and diphosphine) and two
dissociative and exchangeable (namely, bromide and ace-
tate) ligands. This unique combination would potentially
create a plethora of new ruthenium(II) catalysts based on
Entry
Catalyst
t [h]
Yield [%]
1
2
3
4
5
6
7
8
9
2
2
2
1
3
4
5
6a
6b
8
12
24
30
24
24
24
24
24
57
68
90
91
52
46
68
48
32
the interaction of the robust [Ru ACHUTNGREUNNG( NSHC) CAHTUNGTRNENUNG( P-P)] core with a
wide range of anions, substrates, and reactive species. An-
other option is to introduce chelating carbene, or dicarbene,
which has been shown to be effective in catalytic transfer
[
a] Experimental conditions: ketone (1 mmol), NaOtBu (0.1 mmol), cata-
lyst (0.01 mmol), 2-propanol (15 mL), T=828C.
[15,17]
hydrogenation,
to this core. We are exploring the cata-
lytic potential of this new system with reference to the rich
II
ally gives the best yields within 24 hours at a catalyst load of
catalytic chemistry that has been established for the [Ru -
[9,20,21]
1
mol%. This result is consistent with the strength of the
A
H
U
G
R
N
N
(PR )
]
2ꢀ3
system. A distinctive feature of this diphos-
3
carbene and diphosphine chelate, as 2 has the strongest Ruꢀ
C and RuꢀP bonds in this series. As this form of transfer hy-
drogenation typically goes through a hydride intermediate
and the bromide–hydride exchange is expected to be facile,
phine–carbene combination is that, as demonstrated in the
isolation of 5 and 6b, alternative geometric isomers can be
stabilized through adjustment of the skeletal traits of the
diphsophine. Such stereochemical tuning, which is lacking
among monodentate phosphines, offers a simple mechanism
to examine the stereogeometrical effect on catalytic efficacy.
the stability of the [Ru
ACTHUNGTRENNU(GN NSHC) ACHTUNGERTNNUNG( P-P)] core could be a deter-
mining factor. Complex 2 has a slight advantage over its pre-
1488
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ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2011, 6, 1485 – 1491

Ruthenium(II) N,S-Heterocyclic Carbene Diphosphine Complexes
1
22.7, 119.1, 113.5 (Ar-Cmeta/ortho, N/S), 76.8–77.3 (Cp-C, overlapping sin-
glets), 76.5 (d, JCP =12.0 Hz; Cp-C), 75.8 (d, JCP =10.0 Hz; Cp-C), 75.5
(dd, JCP =8.6, 7.3 Hz; Cp-C), 72.2 (d, JCP =6.0 Hz; Cp-C), 72.0 (d, JCP
Experimental Section
All manipulations were carried out under a dry nitrogen atmosphere by
=
using standard Schlenk techniques. Complex 1 was prepared according to
7.0 Hz; Cp-C), 71.7(d, JCP=6.0 Hz; Cp-C), 70.5 (d, J =5.0 Hz; Cp-C),
CP
[
11j]
31
the literature method.
Other commercially available chemicals were
56.0 (CH ), 24.4 ppm (CH COO); P NMR (CDCl ): d=49.4, 47.6 ppm
2
3
3
purchased from Sigma–Aldrich. All solvents were freshly distilled from
standard drying agents. H (500.1), P (202.4) and C(125.8 MHz) NMR
(d, JPP =24.8 Hz); MS (ESI, positive mode): m/z (%): 940.09 (100)
1
31
13
+
[MꢀBr] ; elemental analysis calcd (%) for C H BrFeNO P RuS: C
5
0
42
2 2
spectra were recorded in ppm on a Bruker AMX 500 spectrometer. The
58.89, H 4.15, N 1.37; found: C 58.89, H 4.14, N 1.48.
1
13
1
chemical shifts (d) are referenced to TMS for H and C{ H} and H
3
PO
4
3
1
1
2
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(85%) for P{ H}. ESI mass spectra were obtained by using a Finnigan
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
(MeCOO)
A
H
U
G
R
N
N
LCQ. Elemental analyses were performed on a Perkin–Elmer PE 2400
elemental analyzer. The yields of transfer hydrogenation products were
determined by using Hewlett Packard Series 6890 GC (Santa Clara, CA,
USA) coupled to a Hewlett Packard 5973 MS detector.
1
Yield: 0.17 g (0.19 mmol, 95%); H NMR (CDCl
3
): d=8.31–8.27 (m, 2H;
Ar-H), 7.99–7.96 (m, 2H; Ar-H), 7.58–7.55 (m, 2H; Ar-H), 7.38–7.29 (m,
2
), 7.23 (m, 3H; Ar-H), 7.15–7.03 (m, 6H; Ar-H), 6.89–
.81 (m, 5H; Ar-H), 6.64 (d, 1H, JHH =8.2 Hz; Ar-H), 4.56 (d, 1H, JHH
9
H; Ar-H, CH
6
=
2
4.0 Hz; CH ), 2.95 (m, 1H; CH2
A
H
U
G
E
N
N
(CH ) CH ), 2.81 (m, 1H; CH2
General Procedures for the Preparation of [RuBr
RBzTh)] Complexes (2–6)
A
H
U
G
R
N
U
G
A
T
N
T
N
U
G
A
H
N
T
E
U
G
2
2
2
2
A
H
U
G
R
N
U
G
2
)
)
2
CH
CH
2
), 2.68–2.61 (m, 2H; CH
), 2.06–1.94 (m, 2H; CH
2
A
T
N
T
N
U
G
2
)
2
CH
2
), 2.14 (m, 1H; CH
), 1.69 (m, 1H; CH
2
A
H
N
T
E
N
G
2
2
2
2
A
H
U
G
E
N
N
2
1
)
2
3
CH
2
2
A
mixture of [RuBr
A
H
U
G
R
N
N
(CH
3
COO)
2
A
H
U
T
E
N
N
(PPh
3
)
2
A
H
U
G
R
N
U
G
2 2 2 3 3
ACHTUNGTREUNNGN( CH ) CH ), 1.46 ppm (s, 3H; CH COO); C NMR (CDCl ): d=229.0
0
.20 mmol) and diphosphorus ligands (0.22 mmol) was suspended in
(JCP =14.9, 13.0 Hz; NCS), 186.2 (CH COO), 144.5, 139.2, 138.9, 137.9,
3
THF. The resultant orange solution was refluxed (2–5 and 6a) or stirred
at RT (6b) for 3 h. Upon cooling, the solvent was removed under
vacuum, leaving a yellow or orange residue, which was then washed sev-
137.5, 135.7, 135.3, 135.1, 134.8, 134.4, 133.8, 132.8, 132.6, 131.7, 129.4,
129.2, 129.0, 128.2, 127.9, 127.7, 127.5, 126.9 (Ar-C), 124.5, 122.4, 118.7,
113.5 (Ar-Cmeta/ortho, N/S), 56.1 (CH ), 27.3 (J =27.9 Hz; CH
2
CP
2
A
H
U
G
R
N
U
(CH ) CH ),
2
2
2
eral times with hexane. The powder product was redissolved in CH
and diffused with hexane. The yellow to orange crystals of 2–6 were ob-
2
Cl
2
25.1–25.0 (m, overlapping singlets; CH2
A
H
U
G
R
N
U
G
2
3
2
2
3
2
1
A
H
U
T
N
N
(CH ) CH ), 20.6 ppm (CH
2
2
2
2
A
H
U
G
R
N
N
2
2
tained within a week.
37.3 ppm (d, J =28.5 Hz); MS (ESI, positive mode): m/z (%): 812.11
PP
+
(
100) [MꢀBr] ; elemental analysis calcd (%) for C44
2 2
H42BrNO P RuS: C
2
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[RuBr
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -dppm)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(MeCOO)
A
H
U
G
R
N
N
(3-RBzTh)] (2)
5
9.26, H 4.75, N 1.57; found: C 59.26, H 4.82, N 1.70.
1
Yield: 0.16 g (0.19 mmol, 94%); H NMR (CDCl
3
): d=8.25–8.22 (m, 2H;
2
A
H
U
G
R
N
U
G
A
H
U
G
R
N
N
(h -dppp)
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
Ar-H), 8.13–8.09 (m, 2H; Ar-H), 7.48–7.32 (m, 10H; Ar-H), 7.29–7.07
m, 10H; Ar-H), 7.07–6.94 (m, 3H; Ar-H), 6.74 (d, 1H,
2
(
J
HH =16.4 Hz;
Yield: 0.16 g (0.18 mmol, 91%); H NMR (CDCl ): d=8.06–8.05 (m, 2H;
Ar-H), 7.85–7.82 (m, 2H; Ar-H), 7.48–7.41 (m, 5H; Ar-H), 7.38 (m, 1H;
Ar-H), 7.30–7.10 (m, 13H; Ar-H), 7.05–6.95 (m, 5H; Ar-H, CH ), 6.84
(d, 1H, JHH =8.2 Hz; Ar-H), 5.16 (d, 1H, JHH =15.8 Hz; CH ), 3.10–2.99
3
2
2
CH
2
), 6.31 (d, 1H,
J
HH =16.4 Hz; CH
2
), 5.22 (m, 1H,
J
PH =15.1, 10.4,
2
2
2
J
HH =10.7 Hz; PCH
P), 1.53 ppm (s, 1H; CH
NCS), 186.1 (CH COO), 137.3, 136.2, 136.0, 134.2, 133.9, 133.3, 133.0,
2
P), 4.93 (m, 1H,
J
PH =14.5, 10.7,
J
HH =10.7 Hz;
2
1
3
PCH
2
3
COO); C NMR (CDCl
3
): d=231.0
2
(
3
(m, 2H; CH CH CH ), 2.66–2.60 (m, 2H; CH CH CH ), 2.45 (m, 1H;
2
2
2
2
1
1
32.9, 132.2, 132.1, 132.0, 131.9, 130.2, 130.1, 129.6, 128.7, 128.6, 128.2,
2 2 2 2 2 2 3
CH CH CH ), 2.08 (m, 1H; CH CH CH ), 1.35 ppm (s, 3H; CH COO);
C NMR (CDCl ): d=227.9 (J =14.0 Hz; NCS), 185.2 (CH COO),
3 CP 3
1
3
27.7, 127.0 (Ar-C), 125.1, 122.8, 119.6, 113.7 (Ar-Cmeta/ortho, N/S), 56.4
3
1
(
CH
2
), 51.0 (JPC =23.0 Hz; PCH
2
P), 24.6 ppm (CH
3
COO); P NMR
145.0, 137.4, 136.4, 136.0, 135.3, 135.2, 135.0, 134.7, 134.3, 134.1, 134.0,
133.3, 133.2, 131.8, 129.4, 129.3, 129.1, 128.2, 128.0, 127.9, 127.7, 127.6,
127.5, 127.4, 127.1, 126.7 (Ar-C), 125.0, 122.9, 119.1, 114.0 (Ar-Cmeta/ortho, N/S),
56.4 (CH ), 29.0 (dd, J =30.9, 4.0 Hz; CH CH CH ), 28.9 (d, J =32.9;
(
CDCl
3
): d=14.2, 11.2 ppm (d, JPP =78.1 Hz); MS (ESI, positive mode):
+
m/z (%): 770.03 (100) [MꢀBr] ; elemental analysis calcd (%) for
C
1
41
H
2 2
36BrNO P RuS: C 57.95, H 4.27, N 1.65; found: C 57.71, H 4.15, N
2
CP
2
2
2
CP
3
1
.64.
CH CH CH ), 24.5 (CH COO), 20.5 ppm (CH CH CH ); P NMR
2
2
2
3
2
2
2
(
CDCl ): d=45.7, 40.5 ppm (d, JPP =40.9 Hz); MS (ESI, positive mode):
3
2
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[RuBr
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -dppv)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(MeCOO)
A
T
N
T
E
U
G
+
m/z (%): 797.9 (100) [MꢀBr] ; elemental analysis calcd (%) for
C
1
43
H
2 2
40BrNO P RuS: C 58.84, H 4.59, N 1.60; found: C 58.68, H 4.97, N
Yield: 0.15 g (0.17 mmol, 87%); H NMR (CDCl
Ar-H), 7.96–7.78 (m, 3H; Ar-H), 7.57–7.47 (m, 3H; Ar-H, CH=CH,
CH ), 7.36–7.19 (m, 14H; Ar-H), 7.12–7.09 (m, 2H; Ar-H), 7.02–6.95 (m,
H; Ar-H, CH=CH), 6.93–6.87 (m, 2H; Ar-H), 6.83–6.79 (m, 1H; Ar-H),
.76 (d, 1H, JHH =16.4 Hz; CH
): d=229.0 (NCS), 186.1 (CH
CH=CH), 145.3 (JCP =24.9, 23.9 Hz; CH=CH), 144.3, 137.6, 136.1, 135.7,
3
): d=8.30–8.21 (m, 3H;
.38.
2
2
A
H
U
G
R
N
U
G
A
H
U
G
R
N
N
(h -dppp)
A
H
U
G
R
N
U
G
A
H
U
G
R
N
U
G
3
5
(
2
13
1
3
COO); C NMR
Yield: 0.11 g (0.12 mmol, 61%); H NMR (CDCl ): d=8.05–8.03 (m, 2H;
Ar-H), 7.69 (d, 1H; Ar-H), 7.45–7.08 (m, 21H; Ar-H), 6.82–6.60 (m, 6H;
Ar-H), 5.95 (d, 1H, JHH =15.8 Hz; CH ), 5.86 (d, 1H, J =15.8 Hz;
3
CDCl
3
2
2
HH
1
1
1
2
1
34.5, 134.4, 133.7, 133.3, 133.1, 133.0, 132.6, 132.4, 132.3, 132.2, 132.0,
31.8, 130.2, 129.8. 129.6, 128.5, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8,
2 2 2 2 2 2 2
CH ), 3.00 (m, 1H; CH CH CH ), 2.84–2.77 (m, 2H; CH CH CH ), 2.46–
2.22 (m, 2H; CH CH CH ), 1.77 (m, 1H; CH CH CH ), 1.06 ppm (s, 3H;
2
2
2
2
2
2
1
3
27.0 (Ar-C), 124.7, 122.5, 119.2, 113.4 (Ar-Cmeta/ortho, N/S), 56.6 (CH
2
),
=
3 3 3
CH COO); C NMR (CDCl ): d=185.1 (CH COO), 144.3, 137.3, 136.8,
3
1
4.6 ppm (CH
3.6 Hz); MS (ESI, positive mode): m/z (%): 782.03 (100) [MꢀBr] ; ele-
36BrNO RuS: C 58.54, H 4.21, N
3
COO); P NMR (CDCl
3
): d=87.5, 84.9 ppm (d, JPP
136.2, 135.9, 134.9, 134.8, 134.3, 134.1, 134.0, 133.3, 130.2, 129.9, 129.1,
128.4, 127.9, 127.8, 127.7, 127.6, 127.4, 126.8, 126.7, 125.5, 125.0, 124.8,
123.3, 121.0, 113.6 (Ar-C), 56.2 (CH ), 27.4 (CH CH CH ), 27.2
+
mental analysis calcd (%) for C42
H
2 2
P
2
2
2
2
3
1
1
.62; found: C 58.11, H 4.15, N 1.60.
(CH CH CH ), 23.7 (CH COO), 21.4 ppm (CH CH CH ); P NMR
2
2
2
3
2
2
2
(
7
CDCl ): d=54.2, 14.6 ppm (m); MS (ESI, positive mode): m/z (%):
97.9 (100) [MꢀBr] .
3
2
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[RuBr
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(h -dppf)
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(MeCOO)
A
H
U
G
R
N
N
(3-RBzTh)] (4)
+
1
Yield: 0.16 g (0.17 mmol, 83%); H NMR (CDCl
H), 7.84 (m, 2H; Ar-H), 7.61 (m, 2H; Ar-H), 7.29–7.27 (m, 7H; Ar-H),
.24–7.17 (m, 5H; Ar-H), 7.15–7.09 (m, 5H; Ar-H), 7.04–7.01 (m, 2H;
3
): d=8.02 (m, 2H; Ar-
General Procedure for the Transfer Hydrogenation Reaction
7
The transfer hydrogenation experiments were carried out by using stan-
dard Schlenk techniques. A mixture of an appropriate amount of 2–6
(1 mol%) and the ketone (1 mmol) was dissolved in 2-propanol (20 mL).
The solution was heated to 828C. The reaction commenced immediately
upon addition of 0.1m NaOtBu (1 mL). After ~24 h reflux, the mixture
2
Ar-H, CH
2
), 6.98–6.94 (m, 5H; Ar-H), 6.13 (d, 1H, JHH =16.4 Hz; CH
2
),
5
3
(
.08 (s, 1H; Cp-H), 4.79 (m, 2H; Cp-H), 4.46 (m, 2H; Cp-H), 4.36 (m,
H; Cp-H), 1.14 ppm (s, 3H; CH
CP =14.0, 13.0 Hz; NCS), 186.6 (CH
1
3
3
COO); C NMR (CDCl
3
): d=230.2
J
3
COO), 145.0, 139.6, 139.2, 138.0,
1
1
36.4, 136.1, 135.8, 134.8, 134.5, 134.4, 134.3, 134.2, 134.1, 133.6, 133.5,
29.3, 128.9, 128.7, 128.1, 127.6, 127.2, 127.1, 127.0, 126.8 (Ar-C), 124.8,
was passed through a small column of silica gel and eluted with Et
The crude product was collected for GC-mass chromatography analysis.
2
O.
Chem. Asian J. 2011, 6, 1485 – 1491
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
1489

N. Ding and T. S. A. Hor
FULL PAPERS
Table 4. Summary of crystallographic parameters and refinement results for complexes 2–6.
2
3
4
5
6a
6b
formula
C
41
H
36BrNO2·25
P
2
RuS
C
42
H37BrNO2·50
P
2
RuS
C
52
H
46BrCl
4
FeNO
2
P
2
RuS
C
44 2 2 45 6 2 2 43 2 2
H42BrNO P RuS C H42BrCl NO P RuS C H39BrNO P RuS
F
w
853.69
870.71
monoclinic
P21/n
13.2523(6)
10.7742(5)
26.924(1)
90
99.429(1)
90
3792.4(3)
4
1189.53
monoclinic
P21/n
16.771(7)
16.975(7)
18.167(8)
90
108.42(1)
90
4907(4)
4
891.77
orthorhombic
Pbca
11.9272(5)
19.5253(8)
32.640(1)
90
1116.48
triclinic
Pꢀ1
876.73
crystal system monoclinic
space group
a [ꢁ]
b [ꢁ]
c [ꢁ]
a [8]
b [8]
g [8]
V [ꢁ ]
Z
triclinic
Pꢀ1
P21/n
12.648(1)
11.625(1)
25.720(2)
90
95.695(2)
90
3762.8(6)
4
8.782(1)
14.294(2)
19.356(3)
107.130(3)
98.111(3)
95.118(3)
2276.5(6)
2
10.318(1)
12/481(1)
16.283(1)
103.897(3)
101.402(2)
106.085(3)
1875.6(4)
2
90
90
3
7601.2(5)
8
1.558
ꢀ
3
D
m [mm
calcd [gcm
]
1.507
1.656
1.525
1.645
1.610
1.786
1.629
1.730
1.552
1.663
ꢀ
1
]
1.643
F
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(000)
1728
1764
2400
3632
1124
890
no. of reflns
collected
26079
26039
33942
52301
29231
13429
no. of unique 8633
reflns
8679
11245
8732
10458
8548
R
int
0.0481
6342
0.0685
6371
0.1131
7363
0.0714
6898
0.0731
8665
0.0374
6539
no. of ob-
served reflns
parameters
T [K]
R1 (all data) 0.0662
wR2
477
223(2)
467
587
470
533
546
223(2)
0.0820
0.1179
100(2)
0.1259
0.2136
100(2)
0.0601
0.1073
100(2)
0.1039
0.1802
100(2)
0.0795
0.1964
[
a]
[
b]
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(all
0.1027
data)
GOF
[
c]
0.991
0.631
ꢀ0.315
1.018
1.003
ꢀ0.542
={wS(jF
1.045
1.853
ꢀ1.682
1/2
1.043
1.391
ꢀ0.530
1.171
1.750
ꢀ1.885
1.049
1.381
ꢀ0.854
ꢀ
3
D1max [eꢁ
D1min [eꢁ
]
ꢀ
3
]
2
2
2
1/2
[
a] R
1
=SjjF
o
jꢀjF
c
jj/SjF
o
j. [b] wR
2
o
jꢀjF
c
j) /SwjF
o
j }} . [c] GOF={Sw(jF
o
jꢀjF
c
j) /
A
H
U
G
E
N
N
(nꢀp)} , in which n is the number of reflections and p is the
total number of parameters refined.
X-ray Diffraction Studies
Burling, B. M. Paine, M. K. Whittlesey, N-heterocyclic Carbenes in
Synthesis (Ed.: S. P. Nolan), Wiley-VCH, Weinheim, 2006, 27; e) V.
Dragutan, I. Dragutan, L. Delaude, A. Demonceau, Coord. Chem.
Rev. 2007, 251, 765; f) B. Alcaide, P. Almendros, A. Luna, Chem.
Rev. 2009, 109, 3817; g) C. Samojłowicz, M. Bieniek, K. Grela,
Chem. Rev. 2009, 109, 3708.
2] a) R. H. Grubbs, Tetrahedron 2004, 60, 7117; b) D. Wang, K. Wurst,
W. Knolle, U. Decker, L. Prager, S. Naumov, M. R. Buchmeiser,
Angew. Chem. 2008, 120, 3311; Angew. Chem. Int. Ed. 2008, 47,
Suitable crystals were mounted on quartz fibers and X-ray data were col-
lected on a Bruker AXS APEX diffractometer equipped with a CCD de-
tector, by using graphite-monochromated MoKa radiation (l=0.71073 ꢁ).
The data were corrected for Lorentz and polarization effects with the
SMART program suite and for absorption effects with SADABS. The
crystal structures were solved by direct methods and refined by full-
[
2
[22]
matrix least squares on F by using the SHELXTL program package.
In 2, the hydrogen atoms of the partially occupied free water were not lo-
cated, whereas the hydrogen atoms of the water were located from the
difference Fourier map and refined with restraints in bond lengths and
thermal parameters in 3. There are two phenyl rings disordered into two
positions with the corresponding occupancy ratios of 0.51/0.49 and 0.47/
3
267; c) V. L. Chantler, S. L. Chatwin, R. F. R. Jazzar, M. F. Mahon,
˙
O. Saker, M. K. Whittlesey, Dalton Trans. 2008, 2603; d) I. ꢂzdemir,
S. Demir, N. Gꢃrbꢃz, B. C¸ etinkaya, L. Toupet, C. Bruneau, P. H.
Dixneuf, Eur. J. Inorg. Chem. 2009, 1942; e) L. Benhamou, J. Wolf,
V. Cꢄsar, A. Labande, R. Poli, N. Lugan, G. Lavigne, Organometal-
lics 2009, 28, 6981; f) A. Flores-Figueroa, O. Kaufhold, A. Hepp, R.
Frçhlich, F. E. Hahn, Organometallics 2009, 28, 6362; g) L. J. L.
Hꢅller, M. J. Page, S. A. Macgregor, M. F. Mahon, M. K. Whittlesey,
J. Am. Chem. Soc. 2009, 131, 4604; h) Y. Zhang, X. W. Li, S. H.
Hong, Adv. Synth. Catal. 2010, 352, 1779.
0
.53 in 6b. All non-hydrogen atoms were refined anisotropically. Hydro-
gen atoms were calculated in ideal geometries and refined isotropically.
Selected crystal data for complexes 2–6 are summarized in Table 4.
Acknowledgements
[3] a) L. Ackermann, A. Fꢃrstner, T. Weskamp, F. J. Kohl, W. A. Her-
mann, Tetrahedron Lett. 1999, 40, 4787; b) J. Huang, E. D. Stevens,
S. P Nolan, J. L. Petersen, J. Am. Chem. Soc. 1999, 121, 2674; c) M.
Scholl, T. M. Trnka, J. P. Morgan, R. H. Grubbs, Tetrahedron Lett.
1999, 40, 2247.
[4] M. Scholl, S. Ding, C. W. Lee, R. H. Grubbs, Org. Lett. 1999, 1, 953.
[5] a) S. B. Garber, J. S. Kingsbury, B. L. Gray, A. H. Hoveyda, J. Am.
Chem. Soc. 2000, 122, 8168; b) H. Wakamatsu, S. Blechert, Angew.
Chem. 2002, 114, 832; Angew. Chem. Int. Ed. 2002, 41, 794; c) P. L.
Arnold, A. C. Scarisbrick, Organometallics 2004, 23, 2519; d) K.
Vehlow, S. Maechling, S. Blechert, Organometallics 2006, 25, 25;
e) M. Barbasiewicz, A. Szadkowska, R. Bujok, K. Grela, Organome-
tallics 2006, 25, 3599; f) E. Tzur, A. Szadkowska, A. Ben-Asuly, A.
We thank the National University of Singapore (NUS), Ministry of Edu-
cation, and Agency for Science, Technology and Research for financial
support (grant: R-143-000-361-112), G. K. Tan and L. L. Koh for crystal-
lographic assistance, and the staff at the CMMAC of NUS for technical
assistance. We also thank Prof. M. McGlinchey (UC Dublin) and Dr. W.
Zhang (NUS) for helpful discussions.
[
1] a) R. H. Grubbs, S. J. Miller, G. C. Fu, Acc. Chem. Res. 1995, 28,
46; b) T. M. Trnka, R. H. Grubbs, Acc. Chem. Res. 2001, 34, 18;
c) C. M. Che, J. S. Huang, Coord. Chem. Rev. 2002, 231, 151; d) S.
4
1490
www.chemasianj.org
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2011, 6, 1485 – 1491

Ruthenium(II) N,S-Heterocyclic Carbene Diphosphine Complexes
Makal, I. Goldberg, K. Wo z´ niak, K. Grela, N. G. Lemcoff, Chem.
Eur. J. 2010, 16, 8726.
[14] S. P. Reade, D. Nama, M. F. Mahon, P. S. Pregosin, M. K. Whittlesey,
Organometallics 2007, 26, 3484.
[
[
6] a) R. Drozdzak, B. Allaert, N. Ledoux, I. Dragutan, V. Dragutan, F.
Verpoort, Coord. Chem. Rev. 2005, 249, 3055; b) J. B. Binder, I. A.
Guzei, R. T. Raines, Adv. Synth. Catal. 2007, 349, 395.
[15] P. L. Chiu, H. M. Lee, Organometallics 2005, 24, 1692.
[16] a) J. V. Quagliano, L. Schubert, Chem. Rev. 1952, 50, 201; b) F.
Basolo, Prog. Inorg. Chem. 1962, 4, 381; c) G. B. Kauffmann, I. I.
Chernyaev, J. Chem. Educ. 1977, 54, 86; d) J. Vicente, A. Arcas, D.
Bautista, P. G. Jones, Organometallics 1997, 16, 2127; e) B. J. Coe,
S. J. Glenwright, Coord. Chem. Rev. 2000, 203, 5; f) R. H. Crabtree,
The Organometallic Chemistry of the Transition Metals, 5th ed.,
Wiley, New York, 2009; pp. 7.
[17] a) A. A. Danopoulos, S. Winston, W. B. Motherwell, Chem.
Commun. 2002, 1376; b) M. Poyatos, J. A. Mata, E. Falomir, R. H.
Crabtree, E. Peris, Organometallics 2003, 22, 1110; c) W. Baratta, J.
Schuta, E. Herdtweck, W. A. Herrmann, P. Rigo, J. Organomet.
Chem. 2005, 690, 5570; d) I. ꢂzdemir, S. Yasar, B. C¸ etinkaya, Transi-
tion Met. Chem. 2005, 30, 831; e) M. Yi g˘ it, B. Yi g˘ it, I. ꢂzdemir, E.
C¸ etinkaya, B. C¸ etinkaya, Appl. Organomet. Chem. 2006, 20, 322;
f) M. Poyatos, A. Maisse-Francois, S. Bellemin-Laponnaz, E. Peris,
L. H. Gade, J. Organomet. Chem. 2006, 691, 2713; g) Y. Cheng, J. F.
Sun, H. L. Yang, H. J. Xu, Y. Z. Li, X. T. Chen, Z. L. Xue, Organo-
metallics 2009, 28, 819.
[18] a) M. E. van der Boom, D. Milstein, Chem. Rev. 2003, 103, 1759;
b) A. Del Zotto, W. Baratta, M. Ballico, E. Herdtweck, P. Rigo, Or-
ganometallics 2007, 26, 5636; c) W. Baratta, K. Siega, P. Rigo, Chem.
Eur. J. 2007, 13, 7479; d) T. D. Nixon, J. M. J. Williams, M. K. Whit-
tlesey, Dalton Trans. 2009, 753; e) C. Romain, S. Gaillard, M. K.
Elmkaddem, L. C. Toupet, C. D. Fischmeister, C. M. Thomas, J. L.
Renaud, Organometallics 2010, 29, 1992; f) J. M. Walker, A. M. Cox,
R. Wang, G. J. Spivak, Organometallics 2010, 29, 6121; g) P. Singh,
A. K. Singh, Organometallics 2010, 29, 6433.
[19] a) D. Cuervo, M. P. Gamasa, J. Gimeno, Chem. Eur. J. 2004, 10, 425;
b) C. A. Sandoval, Y. H. Li, K. L. Ding, R. Noyori, Chem. Asian. J.
2008, 3, 1801; c) C. Wang, X. F. Wu, J. L. Xiao, Chem. Asian J. 2008,
3, 1750; d) J. F. Bower, I. S. Kim, R. L. Patman, M. J. Krische,
Angew. Chem. 2009, 121, 36; Angew. Chem. Int. Ed. 2009, 48, 34;
e) R. H. Morris, Chem. Soc. Rev. 2009, 38, 2282; f) R. Malacea, R.
Poli, E. Manoury, Coord. Chem. Rev. 2010, 254, 729; g) S. B. Han,
H. Han, M. J. Krische, J. Am. Chem. Soc. 2010, 132, 1760.
7] a) F. E. Hahn, M. Paas, R. Frçhlich, J. Organomet. Chem. 2005, 690,
5
816; b) S. Monfette, D. E. Fogg, Organometallics 2006, 25, 1940;
c) R. Gawin, A. Makal, K. Wo z´ niak, M. Mauduit, K. Grela, Angew.
Chem. 2007, 119, 7344; Angew. Chem. Int. Ed. 2007, 46, 7206;
d) J. S. M. Samec, R. H. Grubbs, Chem. Eur. J. 2008, 14, 2686.
8] a) M. J. Chilvers, R. F. R. Jazzar, M. F. Mahon, M. K. Whittlesey,
Adv. Synth. Catal. 2003, 345, 1111; b) A. E. W. Ledger, M. F. Mahon,
M. K. Whittlesey, J. M. J. Williams, Dalton Trans. 2009, 6941; c) S. P.
Reade, A. L. Acton, M. F. Mahon, T. A. Martin, M. K. Whittlesey,
Eur. J. Inorg. Chem. 2009, 1774.
9] a) T. Suzuki, M. Tokunaga, Y. Wakatsuki, Org. Lett. 2001, 3, 735;
b) O. Krçcher, R. A. Kçppel, A. Baiker, Chem. Commun. 1997, 453;
c) X. M. Zhang, Enantiomer 1999, 4, 541; d) N. Dodo, Y. Matsushi-
ma, M. Uno, K. Onitsuka, S. Takahashi, J. Chem. Soc. Dalton Trans.
[
[
2000, 35; e) C. Six, K. Beck, A. Wegner, W. Leitner, Organometallics
2000, 19, 4639; f) R. Noyori, T. Ohkuma, Angew. Chem. 2001, 113,
40; Angew. Chem. Int. Ed. 2001, 40, 40; g) P. A. M. Slatford, K. J.
Whittlesey, J. M. J. Williams, Tetrahedron Lett. 2006, 47, 6787;
h) M. H. S. A. Hamid, J. M. J. Williams, Chem. Commun. 2007, 725.
[
[
10] G. C. Vougioukalakis, R. H. Grubbs, J. Am. Chem. Soc. 2008, 130,
234.
2
11] a) S. K. Yen, L. L. Koh, F. E. Hahn, H. V. Huynh, T. S. A. Hor, Or-
ganometallics 2006, 25, 5105; b) S. K. Yen, L. L. Koh, H. V. Huynh,
T. S. A. Hor, Dalton Trans. 2007, 3952; c) S. K. Yen, L. L. Koh, H. V.
Huynh, T. S. A. Hor, Dalton Trans. 2008, 699; d) S. K. Yen, L. L.
Koh, H. V. Huynh, T. S. A. Hor, Chem. Asian J. 2008, 3, 1649;
e) N. N. Ding, J. Zhang, T. S. A. Hor, Dalton Trans. 2009, 1853;
f) X. Y. Han, L. L. Koh, Z. Q. Weng, T. S. A. Hor, Dalton Trans.
2
009, 7248; g) S. K. Yen, D. J. Young, H. V. Huynh, L. L. Koh,
T. S. A. Hor, Chem. Commun. 2009, 6831; h) S. W. Chien, S. K. Yen,
T. S. A. Hor, Aust. J. Chem. 2010, 63, 727; i) X. Y. Han, L. L. Koh,
Z. P. Liu, Z. Weng, T. S. A. Hor, Organometallics 2010, 29, 2403;
j) N. Ding, T. S. A. Hor, Dalton Trans. 2010, 39, 10179.
[
[
12] X. L. Lu, S. Y. Ng, J. J. Vittal, G. K. Tan, L. Y. Goh, T. S. A. Hor, J.
Organomet. Chem. 2003, 688, 100.
13] a) S. W. Chien, T. S. Andy Hor, Ferrocenes: Ligands, Materials and
Biomoleculs; P. Stepnicka, Eds, Wiley-VCH, Weinheim, 2008,
Chap. 2, p. 33; b) J. A. M. Simoes, J. L. Beauchamp, Chem. Rev.
[20] a) G. Zassinovich, G. Mestroni, S. Gladiali, Chem. Rev. 1992, 92,
1051; b) T. Naota, H. Takaya, S. I. Murahashi, Chem. Rev. 1998, 98,
2599; c) B. M. Trost, F. D. Toste, A. B. Pinkerton, Chem. Rev. 2001,
101, 2067.
[21] a) K. R. Flower, Y. J. Howard, R. G. Pritchard, J. E. Warren, Orga-
nometallics 2002, 21, 1184; b) Jan-E. Bꢅckvall, J. Organomet. Chem.
2002, 652, 105.
1
990, 90, 629; c) S. P. Nolan, Bonding Energetics of Organometallic
Compounds. In Encyclopedia of Inorganic Chemistry, Wiley, New
York, 1994; d) L. Luo, N. Zhu, N. J. Zhu, E. D. Stevens, S. P. Nolan,
Organometallics 1994, 13, 669; e) C. Li, M. E. Cucullu, R. A. McIn-
tyre, E. D. Stevens, S. P. Nolan, Organometallics 1994, 13, 3621; f) R.
Noyori, S. Hashiguchi, Acc. Chem. Res. 1997, 30, 97; g) A. B. Chap-
lin, C. Fellay, G. Laurenczy, P. J. Dyson, Organometallics 2007, 26,
[22] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure Refine-
ment; University of Gçttingen, Gçttingen, Germany, 1997.
Received: December 27, 2010
Published online: April 15, 2011
5
86; h) R. Hoffmann, H. Hopf, Angew. Chem. 2008, 120, 4548;
Angew. Chem. Int. Ed. 2008, 47, 4474.
Chem. Asian J. 2011, 6, 1485 – 1491
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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