Synthesis and catalytic activity of ruthenium(II) complexes containing pyridine-based tridentate triamines (′ NNN ′) and pyridine carboxylate ligands (NO )

Article abstract of DOI:10.1016/j.ica.2012.02.034

The reaction of [(p-cymene)RuCl₂]₂ with K[NO _a-b] (NO^- = 2-picolinate, a or 2-quinaldinate, b) gave neutral [(p-cymene)RuCl(NO_a-b)] (1a-b), complexes which were treated with pyridine-based meridional triamine ligands (^′NNN ^′) to create complexes of the type [RuCl(NO_a-b) (^′NNN^′)] (2a: ′N = N_d, NOa- = 2-picolinato; 2b: ′N = N_d, NOb- = 2-quinaldinato; 3a: ′N = N_b, NOa- = 2-picolinato; 3b: ′N = N_b, NOb- = 2-quinaldinato; 4a: ′N = N_p, NOa- = 2-picolinato; 4b: ′N = N_p, NOb- = 2-quinaldinato). The new compounds were characterized by elemental analysis, IR and NMR spectroscopy and, 1b was studied by single crystal X-ray diffraction. The complexes 1-4 have been employed as catalysts for the transfer hydrogenation (TH) of acetophenone derivatives to secondary alcohols in the presence of KOH using 2-propanol as a hydrogen source at 82 °C. The highest catalytic activity was obtained with 3a.

Full text of DOI:10.1016/j.ica.2012.02.034

Inorganica Chimica Acta 392 (2012) 246–253
Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis and catalytic activity of ruthe_n_ium(II) complexes containing
_
pyridine-based tridentate triamines (0NNN0) and pyridine carboxylate ligands (NO)
b,
c
b
d
Osman Dayan a, , Namık Özdemir , Zafer Sßerbetci , Muharrem Dinçer , Bekir Çetinkaya ,
⇑
⇑
Orhan Büyükgüngör b
a Çanakkale Onsekiz Mart University, Laboratory of Inorganic Synthesis and Molecular Catalysis, 17020 Çanakkale, Turkey
b Ondokuz Mayıs University, Faculty of Sciences and Art, Department of Physics, 55139 Samsun, Turkey
c Bingöl University, Faculty of Sciences and Art, Department of Chemistry, 12000 Bingöl, Turkey
d Ege University, Department of Chemistry, 35100 Izmir, Turkey
a r t i c l e i n f o
a b s t r a c t
_
_
The reaction of [(p-cymene)RuCl2]2 with K[NOaꢀb] (NOꢀ = 2-picolinate, a or 2-quinaldinate, b) gave
Article history:
_
Received 7 November 2011
Received in revised form 13 February 2012
Accepted 20 February 2012
Available online 8 March 2012
neutral [(p-cymene)RuCl(NOaꢀb)] (1a–b), complexes which were tre_ated with pyridine-based me_ridional
__
__
triamine ligands (0NNN0) to create complexes of the type [RuCl(NOaꢀb)(0NNN0)] (2a: 0N = Nd, NOꢀa = 2-
_
_
_
picolinato; 2b: N = Nd, NOꢀb = 2-quinaldinato; 3a: N = Nb, NOꢀa = 2-picolinato; 3b: N = Nb, NOꢀb = 2-qui-
0
0
0
_
_
naldinato; 4a: 0N = Np, NOꢀa = 2-picolinato; 4b: 0N = Np, NOꢀb = 2-quinaldinato). The new compounds were
characterized by elemental analysis, IR and NMR spectroscopy and, 1b was studied by single crystal X-ray
diffraction. The complexes 1–4 have been employed as catalysts for the transfer hydrogenation (TH) of
acetophenone derivatives to secondary alcohols in the presence of KOH using 2-propanol as a hydrogen
source at 82 °C. The highest catalytic activity was obtained with 3a.
Keywords:
_
Bidentate NOꢀ donors
Tridentate triamine ligands
Ruthenium complexes
Transfer hydrogenation
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
and pyridine-based carboxylate ligands are scarce [35–41]. The car-
boxylate oxygen is a hard donor and stabilizes the higher oxidation
The transfer hydrogenation (TH) of ketones using Ru(II) com-
plexes bearing C, N, O, and P donor ligands as catalysts have at-
tracted much attention because of their easier and safer operation
compared with other hydrogenation techniques such as using
molecular hydrogen [1–16]. Many studies during the last decade
have been designed to identify a good Ru(II) catalyst for the TH of
ketones. These studies show that the steric and electronic proper-
ties of the ligands in Ru(II) complexes are critically important. In
state of ruthenium. Furthermore, the presence of negatively
charged Oꢀ of the carboxylate makes trans Ru–Cl bond liable to dis-
sociation. Therefore, we have attempted to combine those ligands
in the same complex. A series of Ru(II) complexes have been syn-
thesized and characterized by various spectroscopic techniques.
Synthesized complexes (1–4) have been employed as catalysts,
with a view to understand and compare the influence of bidentate
_
_
ligands (NN [22] versus NOꢀ), on the TH of acetophenone
derivatives.
this respect, tridentate meridional triamines bearing pyridine rings
__
(0NNN0) are good ligands because these are sterically and electron-
ically tunable and form stable complexes with the Ru(II) ion.
__
_
2. Experimental
Recently, some Ru(II) complexes bearing 0NNN0 and bidentate NN li-
gands have been synthesized and successfully applied as catalysts
2.1. Materials and methods
_
for TH [17–23]. Many Ru(II) complexes with bidentate (NOꢀ) or tri-
__
dentate (ꢀONOꢀ) carboxylate ligands bearing pyridine rings have
The manipulations were performed in air, unless otherwise
stated. All reagents and solvents were obtained from commercial
suppliers and used without further purification. 1a [29];
[RuCl2(p-cymene)]2 [42]; dNNNd [43]; bNNNb [44]; pNNNp [45]
were synthesized according to published procedures. NMR spectra
were recorded at 297 K on a Bruker 300 MHz Ultrashield TM NMR
spectrometer at 300 MHz (1H) and 75.48 MHz (13C). Chemical
shifts (d) are given in parts per million, and coupling constants
(J) in hertz (Hz). Atom labeling scheme for NMR assignments was
been synthesized and successfully applied as catalysts for various
__
organic reactions [24–34]. Ru(II) complexes bearing both 0NNN0
__
__
__
⇑
Corresponding authors. Tel.: +90 2862180018 1860; fax: +90 2862180533
(O. Dayan), tel.: +90 3623121919 5256; fax: +90 3624576081 (N. Özdemir).
E-mail addresses: osmandayan@comu.edu.tr (O. Dayan), namiko@omu.edu.tr
(N. Özdemir).
0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2012.02.034

O. Dayan et al. / Inorganica Chimica Acta 392 (2012) 246–253
247
'NNN'
Fig. 1. Atom labeling scheme for NMR assignments.
given in Fig. 1. The C, H, and N analyses were performed using a
CHNS-932 (LECO) instrument. Infrared spectra were measured
with a Perkin Elmer Spectrum One FTIR system and recorded using
(Ar. –CH); 121.9 (Ar. –CH); 129.4 (Ar. –CH); 129.6 (Ar. –CH); 130.0
(Ar. –CH); 130.7 (Ar. –CH); 132.6 (Ar. –CH); 141.0 (Ar. –CH); 147.4
(Ar. –CH); 152.5 (Ar. –CH); 170.8 (–C@O). IR (cmꢀ1): 1654 (
mC@O).
a
universal ATR sampling accessory within the range 550–
_
__
4000 cmꢀ1. Melting points were determined in open capillary
tubes on a digital Stuart SMP10 melting point apparatus. GC mea-
surements for catalytic experiments were performed using a
Younglin Acme 6100 GC instrument with a flame ionization detec-
tor and an Optima 5MS capillary column (The GC parameters were
as follows: oven: 80 °C (isothermal); carrier gas: H2 (split ratio
15:1); flow rate: 4 mL/min; injector port temperature: 220 °C;
2.4. General procedure for the synthesis of [RuCl(NOaꢀb)(0NNN0)] type
complexes; 2–4
2.4.1. Method A
__
A mixture of 0.382 mmol of 1 and 0NNN0 (0.382 mmol) in ethyl-
ene glycol (5 mL) was heated at 130 °C for 1 day during which time
a brown precipitate formed. After cooling to room temperature, the
solid was filtered off and washed with diethyl ether (3 ꢁ 10 mL)
and pentane (3 ꢁ 10 mL). The desired products were dried under
reduced pressure at 50 °C for 1 h.
detector temperature: 280 °C; injection volume: 6.0 lL).
2.2. Computational details
The cis- and trans-isomers of complexes 2–4 in the ground state
were fully optimized using the spin-restricted density functional
theory (DFT) method. The Becke’s three-parameter (B3) nonlocal
exchange functional [46] combined with the Lee, Yang, and Parr
(LYP) correlation functional [47], denoted as B3LYP, was employed
in the DFT calculations. In the optimization process, all atoms have
been represented by the widely used quasi-relativistic LANL2DZ
basis set (Los Alamos effective core pseudo-potential plus dou-
ble-f) [48–50]. The calculations were performed without specify-
ing any symmetry for the complexes by using GAUSS View
molecular visualization program [51] and GAUSSIAN 03 program
package [52]. All the structural optimizations were followed by fre-
quency calculations and no imaginary frequencies were found.
That is to say, the structures obtained from geometry optimiza-
tions correspond to stationary points in the potential surfaces
and they are stationary structures.
2.4.2. Method B
[(p-cymene)RuCl2]2 (117 mg, 0.191 mmol) was dissolved in
__
CH3CN and stirred for 10 min at room temperature. NNN0 ligands
0
(0.382 mmol) were added to this solution, and the resulting mix-
ture was refluxed overnight. At the end of this time, the volatiles
were removed under reduced pressure, and then the residue was
_
dissolved in ethanol (10 mL). K[NOaꢀb](0.382 mmol) was added,
and the mixture was heated under reflux for a further 4 h during
which time a brown precipitate formed. At the end of this time,
the reaction mixture was allowed to cool to room temperature.
The solid was filtered off and washed with water (3 ꢁ 5 mL); cold
ethanol (3 ꢁ 5 mL) and diethyl ether (3 ꢁ 10 mL). The desired
products were dried under reduced pressure at 50 °C for 1 h.
Data for 2a as follows. Yield: 105 mg, 48%. Anal. Calc. for
C27H23ClN4O2Ru: C, 56.69; H, 4.05; N, 9.79. Found: C, 58.79; H, 4.11;
__
N, 9.92%. 1H NMR (d, DMSO-d6): 2.74 (s, 6H, dNNNd–H6); 6.99 (t, 2H,
__
__
_
J1 = 7.8 Hz, J2 = 6.9 Hz, dNNNd–H9); 7.07–7.14 (m, 5H, dNNNd–Ph–
2.3. General procedure for the synthesis of [(p-cymene)RuCl(NOaꢀb)]
_
_
__
type complexes, 1
H + NOa—Hh); 7.30 (m, 1H, NOa–Hg); 7.38–7.47 (m, 4H, dNNNd–
_
_
Ph–H); 7.64 (t, 1H, J = 7.5 Hz, NOa–Hi); 7.89 (t, 1H, J1 = 7.8 Hz,
The reaction mixture containing 1.05 mmol of K[NOaꢀb] and [(p-
__
__
0
J2 = 8.1 Hz, dNNNd–H4); 8.34 (d, 2 H, J = 7.8 Hz, dNNNd–H3,3 ); 9.15
cymene)RuCl2]2 (306 mg, 0.50 mmol) in ethanol (20 mL) was
heated under reflux for 2 h during which time a yellow precipitate
formed. At the end of this time, the reaction was cooled to room
temperature. The solid was filtered off and washed with water
(3 ꢁ 5 mL); cold ethanol (3 ꢁ 5 mL) and diethyl ether (3 ꢁ 5 mL),
respectively. The desired products were dried under reduced pres-
sure at 50 °C for 1 h.
_
(d, 1H; J = 4.8 Hz, NOa–Hj). 13C NMR (d, DMSO-d6): 17.6 (–CH3);
121.1 (Ar. –CH); 124.4 (Ar. –CH); 124.9 (Ar. –CH); 126.0 (Ar. –CH);
126.8 (Ar. –CH); 127.7 (Ar. –CH); 129.0 (Ar. –CH); 136.0 (Ar. –CH);
148.6 (Ar. –CH); 149.5 (Ar. –CH); 150.7 (Ar. –CH); 161.4 (–C@N–);
171.5 (–C@O). IR (cmꢀ1): 1646 (
mC@O); 1624 (mC@N).
Data for 2b as follows. Yield: 115 mg, 48%. Anal. Calc. for
Data for 1b as follows. Yield: 314 mg, 71%. Anal. Calc. for
C
31H25ClN4O2Ru: C, 59.85; H, 4.05; N, 9.01. Found: C, 59.60; H,
__
C
20H20ClNO2Ru: C, 54.24; H, 4.55; N, 3.16. Found: C, 53.4; H, 4.39;
4.27; N, 8.81%. 1H NMR (d, DMSO-d6): 2.75 (s, 6H, dNNNd–H6);
N, 2.96%. 1H NMR (d, DMSO-d6): 0.89 (d, 3 H, J = 6.6 Hz, He,e ); 1.01
0
__
__
0
(d, 3 H, J = 7.2 Hz, He,e ); 2.19 (s, 3 H, Ha); 2.39–2.52 (m, 1H, Hd);
6.80–6.87 (m, 4H, dNNNd–Ph–H); 7.89 (t, 2H, J = 8.1 Hz, dNNNd–
__
0
0
0
5.75–5.84 (m, 3 H, Hb,b –c,c ); 5.98 (d, 1H, J = 6.3 Hz, Hb,b ); 7.91
(t, 1H, J1 = 7.2 Hz, J2 = 8.1 Hz, NOb–Hk); 7.98 (d, 1H, J = 8.4 Hz,
NOb–Hj); 8._09 (t, 1H, J1 = 8.4 Hz, J2 = 7.2 Hz, NOb–Hl); 8.23 (d, 1H,
_
Ph–H); 7.97 (t, 1H, J = 7.8 Hz, dNNNd–H4), 8.04 (d, 1H, J = 8.1 Hz,
_
_
_
_
NOb–Hj); 8.10–8.14 (m, 2H, NOb–H); 8.20 (d, 2H, J = 8.7 Hz,
_
__
__
J = 6.9 Hz, N_Ob–Hg); 8.68 (d, 1H, J = 8.7 Hz, NOb–Hm); 8.73 (d, 1H,
J = 8.1 Hz, NOb–Hh). 13C NMR (d, DMSO-d6): 18.9 (–CH3); 22.0
(–CH3); 22.4 (–CH3); 30.9 (–CH(CH3)2); 80.0 (Ar. –CH); 80.1
(Ar. –CH); 82.0 (Ar. –CH); 85.8 (Ar. –CH); 101.0 (Ar. –CH); 101.6
0
dNNNd–H3,3 ); 8.29–8.34 (m, 4H, dNNNd–Ph–H); 8.48 (d, 1H,
_
_
J = 7.8 Hz, NOb–Hg); 8.60 (d, 1H, J = 7.8 Hz, NOb–Hm); 9.58 (d, 1H,
_
J = 8.1 Hz, NOb–Hh). 13C NMR (d, DMSO-d6): 17.0 (–CH3); 112.7

248
O. Dayan et al. / Inorganica Chimica Acta 392 (2012) 246–253
Table 1
(Ar. –CH); 114.5 (Ar. –CH); 116.9 (Ar. –CH); 124.4 (Ar. –CH); 125.1
(Ar. –CH); 125.6 (Ar. –CH); 126.4 (Ar. –CH); 126.7 (Ar. –CH); 127.2
(Ar. –CH); 127.3 (Ar. –CH); 127.6 (Ar. –CH); 128.3 (Ar. –CH); 146.0
(Ar. –CH); 147.6 (Ar. –CH); 148.7 (Ar. –CH); 155.8 (Ar. –CH); 161.5
Crystal data and structure refinement parameters for complex 1b.
CCDC deposition No.
Color/shape
802221
brown/sheet
[RuCl(C10H6NO2)(C10H14)]
442.89
296
0.71073 Mo K
monoclinic
P21/c (No. 14)
(Ar. –CH); 171.2 (–C@N–); 173.3 (–C@O). IR (cmꢀ1): 1638 (
mC@O);
Chemical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
1619 (mC@N).
Data for 3a as follows. Yield: 157 mg, 72%. Anal. Calc. for
a
C
25H17ClN6O2Ru: C, 52.68; H, 3.01; N, 14.74. Found: C, 52.16; H,
3.20; N, 14.14%. 1H NMR (d, DMSO-d6): 6.37 (t, 1H, J = 7.2 Hz,
Unit cell parameters
a, b, c (Å)
_
_
NOa–Hh); 7.09–7.20 (m, 1H, m, NOa–Hi); 7.32–7.49 (m,
4
H,
10.8217(4), 17.4917(7), 10.5861(4)
__
__
a
, b,
c
(°)
90, 117.671(3), 90
1774.66(12)
4
1.658
1.047
integration
0.7514, 0.9721
896
bNNNb–Bnz–H); 7.69–7.79 (m, 2H, bNNNb–Bnz–H); 7.97 (d, 1H,
Volume (Å3)
Z
_
__
J = 7.8 Hz, NOa–Hg); 8.06–8.17 (m, 1H, bNNNb–H4); 8.23–8.42 (m,
Dcalc (g/cm3)
__
__
l
(mmꢀ1
)
2H, bNNNb–H3); 8.66–8.91 (m, 2H, bNNNb–Bnz–H); 10.50 (d, 1H,
_
Absorption correction
Tmin, Tmax
J = 4.8 Hz, NOb–Hj). 13C NMR (d, DMSO-d6): 115.3 (Ar. –CH);
115.8 (Ar. –CH); 116.5 (Ar. –CH); 117.9 (Ar. –CH); 118.6 (Ar. –CH);
122.5 (Ar. –CH); 122.9 (Ar. –CH); 124.7 (Ar. –CH); 125.0 (Ar. –CH);
126.8 (Ar. –CH); 128.3 (Ar. –CH); 138.5 (Ar. –CH); 142.3 (Ar. –CH);
143.1 (Ar. –CH); 154.8 (Ar. –CH); 170.6 (–C@O). IR (cmꢀ1): 1628
F(000)
Crystal size (mm3)
Diffractometer/measurement
method
0.33 ꢁ 0.21 ꢁ 0.02
STOE IPDS II/
x scan
Index ranges
ꢀ13 6 h 6 12, ꢀ21 6 k 6 21,
ꢀ13 6 l 6 13
(m
C@O).
Data for 3b as follows. Yield: 177 mg, 75%. Anal. Calc. for
29H19ClN6O2Ru: C, 56.18; H, 3.09; N, 13.55. Found: C, 55.22; H,
3.53; N, 14.11 %. 1H NMR (d, DMSO-d6): 6.44 (d, 1H, J = 8.4 Hz,
h range for data collection (°)
Reflections collected
Independent/observed reflections
Rint
2.33 6 h 6 26.57
12060
C
3678/3036
0.0424
_
__
_
Refinement method
full-matrix least-squares on F2
3678/0/229
NOb–Hj); 7.26–7.58 (m, 8H, bNNNb–Bnz–H + NOb–H); 7.16 (d, 2H,
Data/restraints /parameters
__
__
Goodness-of-fit on F2
1.061
J = 7.2 Hz, bNNNb–Bnz–H); 7.88 (t, 1H, J = 7.8 Hz, bNNNb–H4); 8.16
_
_
Final R indices [I > 2
r
(I)]
R1 = 0.0371, wR2 = 0.0810
R1 = 0.0502, wR2 = 0.0851
0.463, ꢀ0.650
(d, 1H, J = 6.9 Hz, NOb–Hg); 8.26 (d, 1H, J = 8.4 Hz, NOb–Hm); 8.48
R indices (all data)
__
_
qmax, D
qmin (e/Å3)
(d, 2H, J = 7.5 Hz, bNNNb–H3); 8.69 (d, 1H, J = 7.2 Hz, NOb–Hh). 13C
NMR (d, DMSO-d6): 115.4 (Ar. –CH); 116.1 (Ar. –CH); 117.9 (Ar. –
CH); 121.2 (Ar. –CH); 122.0 (Ar. –CH); 122.7 (Ar. –CH); 125.0 (Ar.
–CH); 128.5 (Ar. –CH); 129.0 (Ar. –CH); 130.2 (Ar. –CH); 131.1
(Ar. –CH); 131.8 (Ar. –CH); 136.5 (Ar. –CH); 137.4 (Ar. –CH);
138.1 (Ar. –CH); 140.1 (Ar. –CH); 141.7 (Ar. –CH); 143.1 (Ar. –
CH); 147.2 (Ar. –CH); 148.1 (Ar. –CH); 149.3 (Ar. –CH); 152.7 (Ar.
–CH); 153.7 (Ar. –CH); 154.5 (Ar. –CH); 164.9 (-C@O). IR (cmꢀ1):
D
136.6 (Ar. –CH); 137.6 (Ar. –CH); 150.0 (Ar. –CH); 151.6 (Ar. –
CH); 153.6 (Ar. –CH); 154.0 (–C@O). IR (cmꢀ1): 1618 (
C@O).
m
2.5. General method for transfer hydrogenation of ketones using Ru(II)
complexes as pre-catalysts
1624 (mC@O).
Data for 4a as follows. Yield: 152 mg, 85 %. Anal. Calc. for
In a typical experiment, 3a (0.01 mmol) and acetophenone
(1 mmol) were dissolved in 2-propanol (4 mL). This mixture was
stirred at 82 °C for 10 min. After cooling to room temperature,
the base (0.1 mmol) was added, and the mixture was stirred at
82 °C for 1 h. At the end of time, the mixture was cooled to room
temperature, and diluted with diethyl ether (10 ml), filtered
through a pad of silica gel. The mixture was than analyzed by GC.
C
17H13ClN6O2Ru: C, 43.46; H, 2.79; N, 17.89. Found: C, 43.18; H,
3.15; N, 16.18%. 1H NMR (d, DMSO-d6): 7.37 (d, 2H, J = 2.7 Hz,
__
_
pNNNp–Pz–H); 7.90 (t, 1H, J1 = 5.7 Hz, J2 = 6.0 Hz, NOa–Hh); 7.97
_
__
(d, 1H, J = 7.5 Hz, NOa–Hg); 8.01 (d, 2H, J = 2.7 Hz, pNNNp–H3);
__
8.06 (t, 1H, J1 = 8.7 Hz, J2 = 7.2 Hz, pNNNp–H4); 8.13–8.23 (m, 3H,
__
_
_
pNNNp–Pz–H + NOa–Hi); 9.48 (d, 1H, J = 5.1 Hz, NOa–Hj); 14.00
__
2.6. X-ray crystallography
(br, 2H, pNNNp–NH). 13C NMR (d, DMSO-d6): 98.4 (Ar. –CH); 104.4
(Ar. –CH); 117.0 (Ar. –CH); 122.2 (Ar. –CH); 124.5 (Ar. –CH); 126.4
(Ar. –CH); 131.8 (Ar. –CH); 134.9 (Ar. –CH); 135.4 (Ar. –CH); 151.7
The single crystal X-ray data were collected on a STOE IPDS II
diffractometer at 296 K. Graphite-monochromated Mo K
a radia-
(Ar. –CH); 152.0 (Ar. –CH).153.5 (–C@O). IR (cmꢀ1): 1620 (
mC@O).
tion (k = 0.71073 Å) and the -scan technique were used. The
x
Data for 4b as follows. Yield: 145 mg, 73%. Anal. Calc. for
structure was solved by direct methods using SHELXS-97 [53] and re-
fined through a full-matrix least-squares method using SHELXL-97
[54] implemented in WINGX [55] program suit. Non-hydrogen atoms
were refined with anisotropic displacement parameters. All H
atoms were positioned geometrically and treated using a riding
model, fixing the bond lengths at 0.93, 0.98 and 0.96 Å for aromatic
CH, methine CH and CH3 atoms, respectively. The displacement
parameters of the H atoms were fixed at Uiso(H) = 1.2Ueq (1.5Ueq
for methyl) of their parent atoms. Data collection: X-AREA [56], cell
refinement: X-AREA, data reduction: X-RED32 [56]. Details of the
data collection conditions and the parameters of refinement pro-
cess are given in Table 1. The general-purpose crystallographic tool
PLATON [57] was used for the structure analysis and presentation
of the results.
C
21H15ClN6O2Ru: C, 48.51; H, 2.91; N, 16.16. Found: C, 48.75; H,
__
3.18; N, 15.78%. 1H NMR (d, DMSO-d6): 7.37 (m, 2H, pNNNp–Pz–
__
H); 7.75 (t, 1H, J1 = 6.9 Hz, J2 = 8.1 Hz, pNNNp–H4); 7.82–7.85 (m,
_
__
1H, NOb–H); 7.90 (d, 2H, J = 7.2 Hz, pNNNp–H3); 7.94–8.05 (m,
__
_
2H, pNNNp–Pz–H); 8.09–8.15 (m, 1H, NOb–H); 8.18–8.27 (m, 2H,
_
_
NOb–H); 8.31 (d, 1H, J = 6.9 Hz, NOb–Hm); 8.57 (d, 1H, J = 8.4 Hz,
_
__
NOb–Hh); 13.92 (br, 2H, pNNNp–NH). 13C NMR (d, DMSO-d6):
104.1 (Ar. –CH); 104.6 (Ar. –CH); 104.9 (Ar. –CH); 115.5 (Ar. –
CH); 117.2 (Ar. –CH); 117.9 (Ar. –CH); 118.3 (Ar. –CH); 119.6 (Ar.
–CH); 120.9 (Ar. –CH); 127.6 (Ar. –CH); 128.5 (Ar. –CH); 129.5
(Ar. –CH); 132.0 (Ar. –CH); 135.5 (Ar. –CH); 136.4 (Ar. –CH);

O. Dayan et al. / Inorganica Chimica Acta 392 (2012) 246–253
249
Scheme 1. Synthesis of Ru(II) complexes (1–4).
Synthesized compounds were characterized by elemental anal-
ysis, NMR and IR spectra. Also, the structure of 1b was confirmed
by X-ray crys_ta_llography.
3. Results and discussion
3.1. Synthesis and characterization of Ru(II) complexes
__
__
bNNNb, dNNNd, and pNNNp were synthesized according to a
modified literature procedure in good yield [43–45]. Carboxylic
acid salts were readily prepared by the reaction of the respective
carboxylic acids with KOH in ethanol.__
The synthesis and reaction routes of new Ru(II) complexes (1–4)
ar_e illust_ra_ted in Scheme _1. Complexes of the type [RuCl
(NOaꢀb)(0NNN0)] (2–4) with NOꢀ unsymmetrical chelators are ex-
pected to form two geometrical isomers: the first possibility in-
volves anionic ‘‘Oꢀ’’ of the carboxylate trans to the Ru–Cl bond as
shown in Scheme 1, whereas in the second isomer the neutral
‘‘N’’ of the carboxylate is trans to the Ru–Cl bond. These isomers
are referred to as trans- and cis-conformers here. However, in most
cases only the trans isomer was obta_in_ed. It was assumed that
steric hindrance between meridional 0NNN0 ligands and the biden-
tate ligand prevents the generation of cis-conformer [24]. Further-
more, the DFT calculations predicted that the trans-isomer is
slightly more stable than the cis-isomer [41]. In this work, the total
energies belonging to the optimized structures of the trans- and
cis-isomers of complexes 2–4 calculated at DFT/B3LYP level are
presented in Table S1. As can be seen from the table, the trans-iso-
mers were found to be more stable than the cis- isomers. Therefore,
the complexes 2–4 should also be in trans-form. Table S1 also con-
tains the Mulliken charges on key atoms of the trans- and cis-iso-
mers of the complexes 2–4. As shown in table, the charges on
atoms Cl and O which coordinated Ru(II) in the trans-isomers were
more in the negative direction than those in the cis-isomers, while
the charges on pyridyl Nitrogen in the trans-isomers were less neg-
ative with respect to those in the cis-isomers.
The Ru(II) complexes containing NNN0 ligands (2–4) were syn-
0
thesized using two_different methods. In the first of these methods,
[(p-cymene)RuCl(NOaꢀb)] complexes (1a–b) were synthesized and
__
characterized. Then, 1a–b reacted with the appropriate NNN0 li-
0
gands in ethylene glycol at 130 °C and the resulting air-stable six
coordinated target complexes 2–4 were isolated (Method A). In
__
the other method; [(p-cymene)RuCl2]2 reacts with 0NNN0 in
refluxing CH3CN. Then, this mixture was treated with the carbox-
ylic acid salts to give the corre_spondin_g_complexes (2–4) in ethanol
(Method B). Although [RuCl(NOaꢀb)(0NNN0)] (2–4) complexes were
synthesized using both methods, higher yields were obtained with
the latter.
All compounds are air and moisture stable both in the solid
state and in solution. Although 1a–b are soluble in chlorinated
solvents, DMSO, DMF and MeOH, 2–4 are insoluble in chlorinated
solvents and slightly soluble in DMSO, DMF and MeOH.
The structure of 1a was identified in a recent publication [36].
Other complexes gave 1H and 13C NMR spectra corresponding to
the proposed formulations. In _addition to four doublets and two
triplets for atomic protons of NOb ligand in 1:1:1:1:1 ratio d 8.73
(d), 8.68 (d), 8.83 (d), 8.09 (t), 7.98 (d) and 7.91 (d) ppm, one

250
O. Dayan et al. / Inorganica Chimica Acta 392 (2012) 246–253
Table 2
doublet and one multiplet for aromatic protons of p-cymene li-
gands in 1:3 ratio at d 5.98 (d) ppm and in the range d 5.84–
5.75 ppm, one multiplet, one singlet and two doublet for aliphatic
protons of p-cymene ligand in 1:3:3:3 ratio in the range d 2.52–
2.39 (m) ppm and at d 2.19 (s), 1.01 (d) and 0.89 (d) ppm, respec-
tively were observed in the 1H NMR spectra of 1b.
Selected geometric parameters for complex 1b.
Parameter
Parameter
Bond lengths (Å)
Ru1–Cl1
Ru1–O1
2.4040(9)
2.083(3)
2.126(3)
2.222(4)
2.196(3)
2.169(4)
2.187(4)
2.166(3)
Ru1–C17
O1–C1
O2–C1
N1–C2
N1–C10
C1–C2
2.176(3)
1.296(5)
1.216(5)
1.330(4)
1.372(5)
1.506(5)
1.403(5)
The main points of interest in the 1H NMR spectra of the com-
plexes 2–4 are the loss of the peaks_a_ssigned to the p-cymene
group, and new peaks formed due t_o_0NNN0 ligands. Chemical shifts
Ru1–N1
Ru1–C12
Ru1–C13
Ru1–C14
Ru1–C15
Ru1–C16
of the methyl groups (H6) in the dNNNd backbone were singlets at
C2–C3
__
2.74 for 2a and 2.75 ppm for 2b. H3 and H4 protons in the NNN0
0
backbone were observed as doublets and triplets in a 2:1 ratio at
8.34 and 7.89 ppm for 2a, at 8.20 and 7.97 ppm for 2b, at 8.48
Bond angles (°)
Cl1–Ru1–O1
Cl1–Ru1–N1
Cl1–Ru1–C12
Cl1–Ru1–C13
Cl1–Ru1–C14
Cl1–Ru1–C15
Cl1–Ru1–C16
Cl1–Ru1–C17
O1–Ru1–N1
O1–Ru1–C12
O1–Ru1–C13
88.15(8)
87.15(8)
O1–Ru1–C14
O1–Ru1–C15
O1–Ru1–C16
O1–Ru1–C17
N1–Ru1–C12
N1–Ru1–C13
N1–Ru1–C14
N1–Ru1–C15
N1–Ru1–C16
N1–Ru1–C17
91.97(13)
88.83(13)
114.59(13)
152.60(13)
125.64(14)
163.21(14)
152.50(14)
115.05(13)
92.85(12)
98.06(13)
and 7.88 ppm for 3b and at 7.90 and 7.75 ppm for 4b. On the other
__
92.37(11)
92.73(11)
118.05(11)
156.27(10)
156.70(11)
118.81(11)
77.15(11)
157.20(13)
119.63(14)
hand, H4 and H3 protons in the 0NNN0 backbone__for 3a were
observed as multiplets. While the H4 proton in the 0NNN0 backbone
was observed as a triplet at 8.06 ppm for 4a, H3 protons were ob-
served as multiplets. The total count of carbon peaks for complexes
2–4 matched well with the composition of the complexes.
The strong absorptions in the region of 1654–1618 c_mꢀ1 is as-
signed to the coordinated carboxylate group in the NO ligands
and as expected is observed in case of 1–4. In original ligands, this
vibration is observe around 1694 cmꢀ1 for 2-picolinic acid and
1688 cmꢀ1 for Quinaldic acid, and then the decrease in frequency
is due to coordination.
Torsion angles (°)
O1–C1–C2–N1
O1–C1–C2–C3
ꢀ1.4(5)
O2–C1–C2–N1
O2–C1–C2–C3
177.2(4)
ꢀ1.8(6)
179.7(3)
seat and the
r-bonded nitrogen and carboxylic oxygen atoms of
3.2. Structural description of 1b
quinaldinate ligand and one terminal chloride ligand as the legs
of the piano-stool. The rotational orientation of the arene is such
that atoms Cl1, O1 and N1 are staggered with respect to the arene
C atoms, i.e. when viewed along the arene centroid–Ru bond axis,
the atoms eclipse the arene C–C bonds rather than the C atoms.
The Ru atom adopts a pseudo-octahedral coordination geome-
try, with the arene formally occupying three facial coordination
sites. However, the geometry around the metal atom may be re-
garded as a tetrahedron with considerable trigonal distortion, con-
sidering the linkage to the hydrocarbon as a single bond. Defining X
as the centroid of the aromatic ring, the Ru–X distance is
1.6654(3) Å, and the Cl1–Ru1–X, O1–Ru1–X and N1–Ru1–X angles
are 128.76(3)°, 126.87(8)° and 131.82(7)°, respectively. The Cl1–
Ru1–O1, Cl1–Ru1–N1 and O1–Ru1–N1 bond angles [mean
84.15(9)°] are smaller than the ideal tetrahedral angle (109.47°),
which is compensated for by the opening of the X–Ru–L (L is Cl1,
O1 or N1) angles [mean 129.15(6)°]. There are substantial differ-
ences in the C–C [1.386(6)–1.439(5) Å] and Ru–C [2.166(3)–
2.222(4) Å] distances for the arene ring.
The single crystal of 1b suitable for X-ray crystallography was
grown by diffusing Et2O into the EtOH solution. An ORTEP-3 [58]
view of 1b with the atomic numbering scheme is depicted in
Fig. 2, while selected geometric parameters are given in Table 2.
1b is composed of a quinaldinate ligand with a Ru(II) metal center,
one p-cymene ligand and one Cl ligand, and crystallizes in the cen-
trosymmetric monoclinic space group P21/c with one molecule per
asymmetric unit. In the mononuclear complex, the metal center is
stereogenic. The configuration of the stereogenic ruthenium cen-
ters is determined according to the priority sequence g
6-p-cyme-
ne > Cl > O > N [59–62]. As a result, (S) configuration is assigned
to Ru1 atom.
The complex has the familiar half-sandwich ‘‘three-legged pia-
no-stool’’ geometry with the g6 p-bound arene ring forming the
Fig. 2. A view of complex 1b showing the atom-numbering scheme. Displacement
ellipsoids are drawn at the 30% probability level and H atoms are shown as small
spheres of arbitrary radii.
Fig. 3. Optimization of reaction conditions for transfer hydrogenation of acetophe-
none catalyzed by 3a (0.01 mmol) in 2-propanole at 82 °C.

O. Dayan et al. / Inorganica Chimica Acta 392 (2012) 246–253
251
When the bond lengths in the coordinated quinoline entity are
compared with those in the free quinoline ligand [63], coordination
slightly contracts the quinoline moiety’s O1–C1 bond from
1.314(2) to 1.296(5) Å, while there is no significant change in
N1–C2 and N1–C10 lengths due to coordination.
The O- and N-donor atoms of the quinaldinate ligand form a
five-member metallacycle (containing atoms O1/C1/C2/N1/Ru1)
which adopts an envelope conformation, with the Ru1 atom, the
flap atom, out of the mean plane of the remaining four atoms by
ꢀ0.490(2) Å. The bond lengths of Ru–Cl1, Ru1–O1 and Ru1–N1
are found to be 2.4040(9), 2.083(3) and 2.126(3) Å, respectively.
Many ruthenium-arene complexes with the same coordination
sphere have been characterized crystallographically [64–75].
Inspection of the bond lengths in these examples shows that the
Ru–X, Ru–C, Ru–Cl, Ru–O and Ru–N bond lengths vary from
1.633 to 1.710 Å, from 2.102 to 2.267 Å, from 2.388 to 2.467 Å,
from 1.728 to 2.153 Å and from 2.068 to 2.185 Å, respectively. As
can be seen from these values, the coordination bond lengths in
complex 1b match well with the literature values. The dihedral an-
gle between the quinoline ring system and the benzene ring of the
p-cymene is 32.11(11)°.
The molecular structure of the complex 1b does not exhibit any
intramolecular hydrogen bonds. In the crystal structure, the com-
plexes are connected to each other by means of four intermolecular
Table 3
Catalytic activity for transfer hydrogenation of acetophenone and its derivatives catalyzed by Ru(II) complexes.a
Entries
Substrate
Catalyst
Yielde, %
1
2
3
4
5
6
7
8
1a
1b
2a
2b
3a
3b
4a
4b
1a
1b
2a
2b
3a
3b
4a
4b
1a
1b
2a
2b
3a
3b
4a
4b
1a
1b
2a
2b
3a
3b
4a
4b
1a
1b
2a
2b
3a
3b
4a
4b
1a
1b
2a
2b
3a
3b
4a
4b
66
73
96
89
99 (89)b, (23)c, (39)d
90
93
75
68
79
99
98
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
99 (94)b
99
97
92
64
76
98
95
99 (94)b
96
98
89
63
77
99
95
99 (93)b
97
97
88
51
58
89
83
95
81
85
71
11
8
36
33
38
27
39
23
a
b
c
Reactions were carried out at 82 °C using 1 mmol substrate with 0.01 mmol Ru(II) in 4 mL of 2-propanol for 1 h under air.
Reactions were carried out at 82 °C using 1 mmol substrate with 0.01 mmol Ru(II) in 4 mL of 2-propanol for 0.5 h under air.
Reactions were carried out at 25 °C using 1 mmol substrate with 0.01 mmol Ru(II) in 4 mL of 2-propanol for 1 h under air.
Reactions were carried out at 82 °C using 1 mmol substrate with 0.01 mmol Ru(II) in 4 mL of 2-propanol for 1 h under argon atmosphere.
GC yields, yields are based on methyl aryl keton.
d
e

252
O. Dayan et al. / Inorganica Chimica Acta 392 (2012) 246–253
_
interactions of types C–Hꢂ ꢂ ꢂO and C–Hꢂ ꢂ ꢂCl (Fig. S1). The quinaldi-
nate atom C6 and p-cymene atom C16 in the molecule at (x, y, z)
act as hydrogen-bond donor, via atom H6 and H16, to chloride
atom Cl1 and carbonyl atom O2 in the molecule at (x, ꢀy + 1/2,
z + 1/2), respectively. Together, these form an R22ð13Þ ring [76]. In
addition, the quinaldinate atom C8 at (x, y, z) forms a C–Hꢂ ꢂ ꢂCl con-
tact, with the with chloride atom Cl1 at (ꢀx + 2, ꢀy + 1, ꢀz + 1), via
atom H8, thus forming a centrosymmetric R22ð14Þ ring centered at
(1, 1/2, 1/2). Finally, the p-cymene atom C13 at (x, y, z) forms a
C–Hꢂ ꢂ ꢂO contact, via atom H13, with the carboxylic atom O1 at
(ꢀx + 1, ꢀy + 1, ꢀz), forming a second centrosymmetric R22ð8Þ ring
centred at (1/2, 1/2, 0). The detailed geometry of the intermolecu-
lar interactions is given in Table S2. There are no other significant
interactions in the crystal structure of the complex.
investigated. The catalytic experiments showed that [RuCl(NOaꢀb)
__
(0NNN0)] complexes (2–4) are more active catalyst then [(p-cym-
_
ene)RuCl(NOaꢀb)] (1). The efficiency of the catalyst seems to depend
on the ligands of complexes and the substituents of acetophenone.
When a sterically bulky group such as 20,40,60-trimethyl was used as
a substrate, a constant decrease in the catalytic yield was observed.
_
_
The change of bidentate ligands from NN [22] to NOꢀ, did not in-
crease the rate.
Acknowledgments
This research has been supported by The Scientific and Technical
_
Research Council of Turkey (TUBITAK) (Project No: 107T808). B.Ç.
also thank to TUBA (Turkish Academy of Science) for financial
support.
3.3. Catalytic studies
Appendix A. Supplementary material
Recently, the TH of ketones has been extensively studied, and
novel catalysts are reported continuously. In this work, we
describe the synthesis of a series of novel Ru(II) complexes (1–4)
employed as catalysts for the TH of acetophenone derivatives.
The TH of acetophenone derivatives in the presence of KOH by
2-propanol catalyzed by the Ru(II) complexes (1–4) were carried
out under identical conditions to allow comparison of results
[22]. The first experiments were carried out using 3a as catalyst
CCDC 802221 contains 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. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/j.ica.2012.02.034.
References
and acetophenone as
a
model substrate with acetophe-
none:Ru:KOH in the ratio 100:1:10. Because a limited reactivity
was obtained under these conditions, we attempted to optimize
the reaction conditions using 3a as a catalyst. Reactions were car-
ried out at 82 °C using 1 mmol acetophenone with 0.01 mmol 3a in
4 mL of 2-propanol for 1 h. Firstly, the catalytic experiments were
performed under air, because the catalytic activity decreases under
argon atmosphere [17]. Secondly, the effect of KOH concentration
was investigated. The best catalytic performance was observed
with a 40:1 M ratio of KOH and_3_a (Fig. 3)_.
[1] J.-X. Gao, T. Ikariya, R. Noyori, Organometallics 15 (1996) 1087.
[2] R. Noyori, S. Hashiguchi, Acc. Chem. Res. 30 (1997) 97.
[3] D.A. Alonso, P. Brandt, S.J.M. Nordin, P.G. Andersson, J. Am. Chem. Soc. 121
(1999) 9580.
[4] I. Yamada, R. Noyori, Org. Lett. 2 (2000) 3425.
[5] S.W. Seidel, T.J. Deming, Macromolecules 36 (2003) 969.
[6] E. Peris, R.H. Crabtree, Coordin. Chem. Rev. 248 (2004) 2239.
[7] A.M. Hayes, D.J. Morris, G.J. Clarkson, M. Wills, J. Am. Chem. Soc. 127 (2005)
7318.
[8] W. Baratta, E. Herdtweck, K. Siega, M. Toniutti, P. Rigo, Organometallics 24
(2005) 1660.
[9] T. Ohkuma, N. Utsumi, K. Tsutsumi, K. Murata, C. Sandoval, R. Noyori, J. Am.
Chem. Soc. 27 (2006) 8724.
[10] J. Canivet, G. Labat, H. Stoeckli-Evans, G. Süss-Fink, Eur. J. Inorg. Chem. (2005)
4493.
[11] H. Cheng, R. Liu, J. Hao, Q. Wang, Y. Yu, S. Cai, F. Zhao, Appl. Organomet. Chem.
24 (2010) 763.
[12] J.E.D. Martins, G.J. Clarkson, M. Wills, Org. Lett. 11 (2009) 847.
[13] F.K. Cheung, A.J. Clarke, G.J. Clarkson, D.J. Fox, M.A. Graham, C. Lin, A.L. Criville,
M. Wills, Dalton Trans. 39 (2010) 1395.
0
To investigate the effect of NNN0 and NO, the catalytic activity
of Ru(II) complexes (1–4) were also studied under the same condi-
tions. The Ru(II) complexes of type 1–4 were found to be active cat-
alysts in the transfer hydrogenation of acetophenone and its
derivatives, leading to the formation of sec-alcohol with good to
excellent conversions in 1 h. The results are summarized in Table 3.
As shown in Table 3, complexes of 2-picolinates (a) are more
_
__
reactive than 2-quinaldinates (b). [RuCl(NO)(0NNN0)] com_plexes
(2–4) are more active catalysts than [(p-cymene)RuCl(NOaꢀb)]
[14] W. Baratta, P. Rigo, Eur. J. Inorg. Chem. (2008) 4041.
_
[15] N. Gürbüz, S. Yasßar, E.Ö. Özcan, I. Özdemir, B. Çetinkaya, Eur. J. Inorg. Chem.
(2010) 3051.
complexes (1). Similarly, Type 3 complexes are more active cata-
lysts than other Ru(II) complexes (2 and 4) containing ‘NNN‘ li-
[16] M. Aydemir, A. Baysal, S. Özkar, L. Tatar Yıldırım, Inorg. Chim. Acta 367 (2011)
166.
__
[17] M. Zhao, Z. Yu, S. Yan, Y. Li, Tetrahedron Lett. 50 (2009) 4624.
[18] X.-Y. Lu, H.-J. Xu, X.-T. Chen, Inorg. Chem. Commun. 12 (2009) 887.
[19] O. Dayan, B. Çetinkaya, J. Mol. Catal. A-Chem. 271 (2007) 134.
[20] M. Zhao, Z. Yu, S. Yan, Y. Li, J. Organomet. Chem. 694 (2009) 3068.
[21] F. Zeng, Z. Yu, Organometallics 28 (2009) 1855.
[22] S. Günnaz, N. Özdemir, S. Dayan, O. Dayan, B. Çetinkaya, Organometallics 30
(2011) 4165.
[23] L.T. Ghoochany, S. Farsadpour, Y. Sun, W.R. Thiel, Eur. J. Inorg. Chem. (2011)
3431.
[24] T. Funaki, M. Yanagida, N. Onozawa-Komatsuzaki, K. Kasuga, Y. Kawanishi, H.
Sugihara, Inorg. Chim. Acta 362 (2009) 2519.
gands. For
a period of 1 h the catalytic activity generally
increases in the order: 1 < 4 < 2 < 3.
In reference to substrates, Ru(II) complexes are more efficient
catalysts for electron withdrawing substituents such as Fꢀ, Clꢀ
and Brꢀ on the para-position of the aryl ring of the acetophenone
derivatives. When electron donating group are introduced at the
aryl ring of the ketone, catalytic activity decreases. Generally
speaking, the results are consistent with the finding of other
researchers [77–79].
[25] T. Kundu, B. Sarkar, T.K. Mondal, J. Fiedler, S.M. Mobin, Wo Kaim, G.K. Lahiri,
Inorg. Chem. 49 (2010) 6565.
[26] H.-J. Zhang, B. Demerseman, L. Toupet, Z. Xi, C. Bruneau, Organometallics 28
(2009) 5173.
[27] M. Achard, N. Derrien, H.-J. Zhang, B. Demerseman, C. Bruneau, Org. Lett. 11
(2009) 185.
4. Conclusion
[28] H.-J. Zhang, B. Demerseman, L. Toupet, Z. Xi, C. Bruneau, Adv. Synth. Catal. 350
(2008) 1601.
In this work, a series of _neutral_R_u(II) complexes ([(p-cym-
_
ene)RuCl(NOaꢀb)] (1); [RuCl(NOaꢀb)(0NNN0)] (2–4)) have been syn-
ˇ
´
´
´
´
´
[29] I. Ivanovic, S. Grguric-Šipka, N. Gligorijevic, S. Radulovic, A. Roller, Z. Lj Tešic,
B.K. Keppler, J. Serb. Chem. Soc. 76 (2011) 53.
thesized in good yields by the reaction of [RuCl2(p-cymene)]2
_
[30] S. Tanaka, H. Saburi, M. Kitamura, Adv. Synth. Catal. 348 (2006) 375.
[31] T. Hirakawa, S. Tanaka, N. Usuki, H. Kanzaki, M. Kishimoto, M. Kitamura, Eur. J.
Org. Chem. (2009) 789.
[32] S. Tanaka, H. Saburi, T. Murase, Y. Ishibashi, M. Kitamura, J. Organomet. Chem.
692 (2007) 295.
with the potassium salt of p_yr_idine carboxylates K[NOaꢀb] and tri-
dentate triamine ligands (0NNN0) and their catalytic activities for
the hydrogen transfer reaction of acetophenone derivatives with
the use of 2-propanol in the presence of KOH under air have been

O. Dayan et al. / Inorganica Chimica Acta 392 (2012) 246–253
253
[33] S. Grguric´-Šipka, I. Ivanovic´, G. Rakic´, N. Todorovic´, N. Gligorijevic´, S. Radulovic´,
[53] G.M. Sheldrick, SHELXS-97, Program for the Solution of Crystal Structures,
University of Göttingen, Germany, 1997.
ˇ
V.B. Arion, B.K. Keppler, Z. Lj, Eur. J. Med. Chem. 45 (2010) 1051.
[34] S. Tanaka, H. Saburi, Y. Ishibashi, M. Kitamura, Org. Lett. 6 (2004) 1873.
[35] S. Bhor, G. Anilkumar, M.K. Tse, M. Klawonn, C. Döbler, B. Bitterlich, A.
Grotevendt, M. Beller, Org. Lett. 7 (2005) 3393.
[54] G.M. Sheldrick, SHELXL-97, Program for Crystal Structures Refinement,
University of Göttingen, Germany, 1997.
[55] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.
[36] G. Anilkumar, S. Bhor, M.K. Tse, M. Klawonn, B. Bitterlich, M. Beller,
Tetrahedron: Asymmetr. 16 (2005) 3536.
[56] Stoe & Cie, X-AREA Version 1.18 and X-RED32 Version 1.04, Stoe & Cie, Darmstadt,
Germany, 2002.
[37] M.K. Tse, S. Bhor, M. Klawonn, G. Anilkumar, H. Jiao, C. Döbler, A. Spannenberg,
W. Mägerlein, H. Hugl, M. Beller, Chem.-Eur. J. 12 (2006) 1855.
[38] H. Nishiyama, T. Shimada, H. Itoh, H. Sugiyama, Y. Motoyama, Chem. Commun.
(1997) 1863.
[39] W. Mägerlein, C. Dreisbach, H. Hugl, M.K. Tse, M. Klawonn, S. Bhor, M. Beller,
Catal. Today 121 (2007) 140.
[57] A.L. Spek, J. Appl. Crystallogr. 36 (2003) 7.
[58] L.J. Farrugia, J. Appl. Crystallogr. 30 (1997) 565.
[59] R.S. Cahn, C.K. Ingold, V. Prelog, Angew. Chem. 78 (1966) 413.
[60] R.S. Cahn, C.K. Ingold, V. Prelog, Angew. Chem., Int. Ed. Engl. 5 (1966) 385.
[61] C. Lecomte, Y. Dusausoy, J. Protas, J. Tirouflet, A. Dormond, J. Organomet. Chem.
73 (1974) 67.
[40] F. Shi, M.K. Tse, M. Beller, Chem.-Asian J. 2 (2007) 411.
[41] A.D. Chowdhury, A. Das, K. Irshad, S.M. Mobin, G.K. Lahiri, Inorg. Chem. 50
(2011) 1775.
[42] M.A. Bennett, T.N. Huang, T.W. Matheson, A.K. Smith, Inorg. Synth. 21 (1982)
74.
[62] H. Brunner, Enantiomer 2 (1997) 133.
[63] D. Dobrzyn´ ska, L.B. Jerzykiewicz, J. Chem. Crystallogr. 34 (2004) 51.
[64] A.J. Davenport, D.L. Davies, J. Fawcett, D.R. Russell, Dalton Trans. (2004) 1481.
[65] C. Gemel, R. John, C. Slugovc, K. Mereiter, R. Schmid, K. Kirchner, J. Chem. Soc.,
Dalton Trans. (2000) 2607.
[43] K.J. Miller, T.T. Kitagawa, M.M. Abu-Omar, Organometallics 20 (2001) 4403.
[44] A.W. Addison, P.J. Burke, J. Heterocycl. Chem. 18 (1981) 803.
[45] A.K. Pleier, H. Glas, M. Grosche, P. Sirsch, W.R. Thiel, Synthesis 1 (2001) 55.
[46] A.D. Becke, J. Chem. Phys. 98 (1993) 5648.
[47] C. Lee, W. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785.
[48] P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 270.
[66] A. Habtemariam, M. Melchart, R. Fernández, S. Parsons, I.D.H. Oswald, A.
Parkin, F.P.A. Fabbiani, J.E. Davidson, A. Dawson, R.E. Aird, D.I. Jodrell, P.J.
Sadler, J. Med. Chem. 49 (2006) 6858.
[67] O. Briel, A. Fehn, K. Polborn, W. Beck, Polyhedron 18 (1999) 225.
[68] H. Brunner, B. Nuber, M. Prommesberger, Tetrahedron: Asymmetr. 9 (1998)
3223.
[49] P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 284.
[50] P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 299.
[51] R. Dennington II, T. Keith, J. Millam, GAUSS View, Version 4.1.2, Semichem Inc.,
Shawnee Mission, KS, 2007.
[69] H. Brunner, T. Neuhierl, B. Nuber, Eur. J. Inorg. Chem. (1998) 1877.
[70] R.K. Rath, M. Nethaji, A. Chakravarty, Polyhedron 21 (2002) 1929.
[71] R.K. Rath, M. Nethaji, A.R. Chakravarty, J. Organomet. Chem. 633 (2001) 79.
[72] K.N. Kumar, G. Venkatachalam, R. Ramesh, Y. Liu, Polyhedron 27 (2008) 157.
[73] J.G. Małecki, R. Kruszynski, M. Jaworska, P. Lodowski, Z. Mazurak, J.
Organomet. Chem. 693 (2008) 1096.
[52] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A.
Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox,
H.P. Hratchian, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E.
Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y.
Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S.
Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K.
Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J.
Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L.
Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M.
Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A.
Pople, GAUSSIAN 03, Revision E.01, Gaussian, Inc., Wallingford CT, 2004.
[74] H. Brunner, T. Zwack, M. Zabel, W. Beck, A. Böhm, Organometallics 22 (2003)
1741.
ˇ
ˇ
[75] P. Govindaswamy, B. Therrien, G. Süss-Fink, P. Štepnicka, J. Ludvík, J.
Organomet. Chem. 692 (2007) 1661.
[76] J. Bernstein, R.E. Davis, L. Shimoni, N.-L. Chang, Angew. Chem., Int. Ed. Engl. 34
(1995) 1555.
[77] M. Aydemir, F. Durap, A. Baysal, N. Meric, A. Buldag˘, B. Gümgüm, S. Özkar, L.
Tatar Yıldırım, J. Mol. Catal. A-Chem. 326 (2010) 75.
[78] J.W. Faller, A.R. Lavoie, Organometallics 20 (2001) 5245.
[79] P. Pelagatti, M. Carcelli, F. Calbiani, C. Cassi, L. Elviri, C. Pelizzi, U. Rizzotti, D.
Rogolino, Organometallics 24 (2005) 5836.