Transfer hydrogenation of aryl ketones with half-sandwich RuII complexes that contain chelating diamines

Article abstract of DOI:10.1002/ejic.201200638

In a comparative study, half-sandwich complexes of Ru^II (1) with pyridine-based chelating diamine [NN = 2-aminomethylpiperidine (ampi), a; 2-aminomethylpyridine (ampy), b; 8-aminoquaniline (aquan), c; 4,4'-dimethyl-2,2'-bipyridine (dbipy), d; 2,2'-bipyridine (bipy), e] or amine amide (Ts-ampi, 2a) were synthesized by cleavage of [{(η⁶-p- cymene)Ru(μ-Cl)Cl}₂] dimer and the resulting complexes were screened for their efficiency in the transfer hydrogenation (TH) of acetophenone in 2-propanol (IPA) at 82 °C or in water in HCOONa. Among the complexes, cationic 1a, neutral 2a, and 1b, which bear ampi and ampy, were the most effective in terms of catalyst performance (turnover frequency values: 198, 6000, 23 h^-1, respectively). Copyright

Full text of DOI:10.1002/ejic.201200638

Job/Unit: I20638
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Date: 27-08-12 18:41:02
Pages: 7
FULL PAPER
DOI: 10.1002/ejic.201200638
II
Transfer Hydrogenation of Aryl Ketones with Half-Sandwich Ru Complexes
That Contain Chelating Diamines
[a]
[b]
[a]
˙
Hayati Türkmen,* Ibrahim Kani, and Bekir Çetinkaya
Keywords: Hydrogenation / Ruthenium / N ligands / Ketones / Arenes
II
In a comparative study, half-sandwich complexes of Ru (1)
their efficiency in the transfer hydrogenation (TH) of aceto-
phenone in 2-propanol (IPA) at 82 °C or in water in
HCOONa. Among the complexes, cationic 1a, neutral 2a,
and 1b, which bear ampi and ampy, were the most effective
in terms of catalyst performance (turnover frequency values:
∧
with pyridine-based chelating diamine [N N = 2-amino-
methylpiperidine (ampi), a; 2-aminomethylpyridine (ampy),
b; 8-aminoquaniline (aquan), c; 4,4Ј-dimethyl-2,2Ј-bipyridine
dbipy), d; 2,2Ј-bipyridine (bipy), e] or amine amide (Ts-ampi,
a) were synthesized by cleavage of [{(η -p-cymene)Ru(μ-
(
6
–1
2
198, 6000, 23 h , respectively).
Cl)Cl} ] dimer and the resulting complexes were screened for
2
∧
Introduction
N N ligand with stronger σ donation than ampy. The ampi
ligand is commercially available and relatively cheap, and
its chiral version is known.
[
1]
Since the pioneering work by Noyori and Ikariya et al.,
[10]
6
II
(
η -arene)Ru -catalyzed asymmetric transfer hydrogena-
tion (ATH) reactions have been the subject of increasing
interest because of the advantages of this methodology over
Results and Discussion
[2]
classical hydrogenation reactions. Related reviews deal
[3]
with the TH reaction mechanisms and water-soluble orga-
Cationic complexes (1) were prepared by the reaction of
nometallic complexes.[ 2-Propanol (IPA), HCOOH/NEt3, chelating ligands [N N = 2-aminomethylpiperidine (ampi),
or HCOONa are the most frequently used hydrogen do- a; 2-aminomethylpyridine (ampy), b; 8-aminoquinoline
nors. Monotosylated diamines are among the most effective (aquan), c; 4,4Ј-dimethyl-2,2Ј-bipyridine (dbipy), d; 2,2Ј-bi-
4]
∧
in terms of catalyst performance.[ Rhodium and iridium pyridine (bipy), e] with [{(η -p-cymene)Ru(μ-Cl)Cl}
2]
6
] as de-
2
complexes with various combinations of electron-rich li- picted in Scheme 1. The known complexes (1b, 1d, 1e) are
gands, such as vic-diamines,[ tertiary phosphanes, and also included for comparison purposes. The complexes can
5]
[6]
N-heterocyclic carbenes (NHCs)[ have enlarged the scope be stored in air for a long period of time and are soluble in
of TH reactions. Cleavage reactions of the [{(η -p-cymene)- DMSO, DMF, MeOH, and H
7]
6
O, and insoluble in apolar
2
Ru(μ-Cl)Cl} ] dimer with bipyridyl-based ligands were re- solvents such as hexane. The solubility (at 25 °C) of com-
2
II
ported to give water-soluble half-sandwich Ru complexes, plexes in water is 120 (1a), 112 (1b), 93 (1c); 103 (1d), and
which show good catalytic activity for TH of aryl ketones.
Baratta and co-workers and our group have independently NMR spectroscopy and elemental analysis. The H NMR
reported a number of Ru complexes that bear the 2- spectrum clearly indicates the presence of p-cymene ligands
[
8]
–1
1
13
105 (1e) mgmL . They were characterized by H and
C
1
II
aminomethylpyridine (ampy) group and have examined in all complexes. In the case of complex 1a, the p-cymene
[
9]
their excellent ability to catalyze the reduction of ketones.
resonance appears in the usual range as two doublets at δ
In this report, we extend this approach to prepare water- = 6.27 and 5.88 ppm. However, the p-cymene resonance of
soluble half-sandwich ruthenium complexes with pyridine- complex 1c shows four different doublets for the aryl pro-
∧
13
based bidentate N N ligands and compare their efficiences tons. All complexes gave C NMR spectra that correspond
in TH reactions. We decided to include 2-aminomethyl- to the proposed formulation.
piperidine (ampi) because we anticipated that such func-
tional groups (reduced pyridine and NH) would produce an
Description of Structure
An ORTEP representation of complex 1a is shown in
Figure 1. The complex crystallizes in an orthorhombic
noncentrosymmetric system with Z = 4 in space group
[
a] Department of Chemistry, Ege University,
3
5100 Bornova-Izmir, Turkey
E-mail: hayatiturkmen@hotmail.com
hayati.turkmen@ege.edu.tr
P2 2 2 . The significant bond lengths and bond angles are
[
b] Department of Chemistry, Anadolu University,
1 1 1
26470 Eskisehir, Turkey
listed in Table 1. The cationic mononuclear complex con-
Eur. J. Inorg. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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H. Türkmen, I˙ . Kani, B. Çetinkaya
FULL PAPER
Scheme 1. Synthesis of the cationic ruthenium–arene complexes.
6
6
sists of a ruthenium atom coordinated to the η -p-cymene Ru–C distances in η -arene fall within the usual range
ligand that occupies the facial coordination site, to the two 2.165(3)–2.406(9) Å and are quite similar to other related
6
[11]
nitrogen atoms of the 2-aminomethylpiperidine ligand, and Ru–η -arene complexes. The two Ru–N bond lengths are
to a chlorine atom, with the coordination geometry of ru- slightly different [2.125(2) and 2.155(3) Å]. The Ru–Cl bond
thenium being a pseudotetrahedral arrangement (Figure 1). length of 2.4059(8) Å is also essentially similar and quite
In the crystal structure, one chlorine atom exists as a coun- comparable to those of other cationic ruthenium com-
[
12]
terion. The ruthenium atom is situated 1.670 Å away from plexes. The bite angle of the 2-aminomethylpiperidine li-
the centroid of the p-cymene moiety. The interaction dis- gand is 79.47(11)°.
tance is similar to those found in cationic Ru complexes,
+
+2 [8d]
[
(C Me )Ru(phen)(Cl)] and [(C Me )Ru(phen)(OH )] .
6 6 6 6 2
Catalytic Studies
All complexes 1–2a were studied for the transfer hydro-
genation of acetophenone to give phenylethanol in 2-prop-
anol at 82 °C (Table 2). Over a 30 min period the catalytic
activity decreases in the order 1a Ͼ 1b Ͼ 1c Ͼ 1d ≈ 1e. The
highest activity was observed for the 2-aminomethylpiper-
idine derivative 1a. For example, comparison of ampi (1a)
and the ampy (1b) complexes clearly indicated their differ-
[
9g]
ences (Table 2, entries 1–4).
On the other hand, aquan
analogue 1c was less active under the same conditions. Ap-
∧
parently, electronic effects and the presence of N N ligand
increased the activity of the cationic complex. Despite the
different electronic effects of the 4-CH and 4-H substitu-
3
ents of the bipy skeleton on 1d and 1e, respectively, the ac-
tivity of 1d and 1e was surprisingly very similar. Consistent
Table 2. Catalytic activity for transfer hydrogenation of aceto-
phenone catalyzed by Ru complexes.
II
[a]
Figure 1. A view of complex 1a showing 50% probability displace-
ment ellipsoids and the atom-numbering scheme.
Table 1. Selected bond lengths and angles [°] of complex 1a.
Bond lengths [Å]
Bond angles [°]
Entry
Cat.
t [min]
Conversion [%][b]
TOF[c]
Ru1–N2
Ru1–N1
Ru1–C6
Ru1–C7
Ru1–C4
Ru1–C3
Ru1–C5
Ru1–C2
Ru1–Cl1
C12–N1
2.126(3)
N2–Ru1–N1
N2–Ru1–C6
N1–Ru1–C6
N2–Ru1–C7
N1–Ru1–C7
N2–Ru1–C4
N1–Ru1–C4
N2–Ru1–C3
N1–Ru1–C3
N2–Ru1–C5
79.47(11)
90.69(12)
119.89(12)
114.71(12)
94.43(12)
122.51(12)
157.63(12)
160.42(12)
120.09(12)
93.95(12)
1
2
3
4
5
6
7
8
1a
1a
1b
1b
1c
1d
1e
30
15
30
15
30
30
30
30
99
66
52
03
46
34
31
05
198
–
23
–
17
11
9
2.153(3)
2.165(3)
2.169(3)
2.188(3)
2.195(3)
2.205(3)
2.225(4)
2.4059(8)
1.491(4)
[{p-cymRuCl
2 2
} ]
0.4
[
5
a] Method A: [S]/[cat] = 100, 82 °C, KOH, in IPA. [b] Based on
min conversion. [c] Turnover frequency (TOF) in molmol h .
–
1
–1
2
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Transfer Hydrogenation of Aryl Ketones
with the previous observations, ligands that bore N(H) and Ru(μ-Cl)Cl} ] with the monotosylated N-tosyl-1-piperidin-
2
NH entities (1a–1c) showed higher activities than the com- 2-ylmethanamine at 65 °C in chloroform gave a brown pre-
2
plexes without (1d, 1e). Under the same conditions, the di- cipitate, which was purified by column chromatography on
6
mer [{(η -p-cymene)Ru(μ-Cl)Cl} ] performed poorly with silica gel by using dichloromethane as eluent. Ligand 2 and
2
1
13
5
% conversion (entry 8).
orange complex 2a were characterized by H and C NMR
Since the arene–ruthenium complexes synthesized here spectroscopy and elemental analysis.
are water-soluble, we also assessed their TH activity in the
presence of formic acid and sodium formate as a hydrogen-
donor source in water. We surveyed the effect of bases, the
catalyst loading, and reaction times on the TH of aceto-
phenone by using complex 1a as a ruthenium source
(Table 3). Ogo and co-workers reported the TH of ketones
by HCOONa or HCOOH in water with water-soluble half-
II
sandwich Ru complexes. The best results were obtained at
pH = 3.8 (i.e., the pK of formic acid) for an equimolar
a
radio of HCOOH/HCOONa (2.5 equiv. of each relative to
[
8c]
the substrate). Under these conditions, the product was
obtained in 92% conversion within 4 h (Table 3, entry 1).
The use of 2.5 equiv. of HCOONa or HCOOH led to lower
conversions (72 and 10%, respectively). A decrease in
HCOONa to 1.0 equiv. led to a decrease in conversion (en-
try 7). When the catalyst loading decreased from 1 to
0.01%, a slightly lower conversion was obtained (entries 1
and 8). To test the catalyst performance at lower tempera-
tures, the transfer hydrogenation of acetophenone was de-
Having isolated complex 2a, we then carried out catalytic
termined at temperatures from 25–82 °C. Temperature-de- studies in TH and compared the methods used above. As
pendent studies between 25, 50, and 65 °C afforded moder- can be seen from the data shown in Table 3, 2a is very active
ate yields (entries 9–11).
in transfer hyrogenation in water (Table 3, entry 12) when
We also performed an additional experiment to assess catalyst loadings of 10–1 or even 10 mol-% were used (en-
–2
the relative reactivity of complex 2a toward transfer hydro- tries 13 and 14); however, the activity dramatically de-
6
genation of acetophenone. The reaction of [{(η -p-cymene)- creased at lower catalyst loadings. Aqua complex 3a, gener-
ated in situ with AgBF in aqueous solution, was tested in
4
TH by using acetophenone as a substrate. The effect of the
aqua ligand on the activity with 3a was not noticeable (en-
try 15). Previously, the beneficial effect of donor substitu-
Table 3. Screening of bases and/or hydrogen donor in water.
ents at the arene ligand was studied by Süss-Fink et al. and
[
5,8f]
Renaud et al.
They observed that p-cymene gave the
best result on TH and it was proposed that p-cymene ligand
is the best compromise between steric effects and electron
density on the ruthenium. We also performed the catalytic
study in the presence of free p-cymene in methods B and C,
but the conversion did not differ significantly. This indicates
that p-cymene does not dissociate during the catalytic
events that involve 1a or 2a.
Entry
Cat.
mol-%]
Hydrogen donor [mmol]
t [min]
Conv. [%]
[
[
a]
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
0.01
1
1
1
1
0.1
0.01
1
NaO
NaO
NaO
NaO
HCO
HCO
NaO
NaO
NaO
NaO
NaO
NaO
NaO
NaO
NaO
NaO
NaO
2
CH/HCO
CH/HCO
2
H (2.5:2.5)
H (2.5:2.5)
240
960
240
960
240
960
240
240
240
240
240
1
1
1
1
240
1
92
[
a]
2
2
99
[
a]
2
CH(2.5)
CH(2.5)
77
[
a]
2
93
[
a]
2
H (2.5)
H (2.5)
CH(1.0)
10
[
a]
To further explore the effectiveness of catalyst 1a and 2a
on other substrates, 4-chloroacetophenone, 2-chloroaceto-
phenone, 4-bromoacetophenone, 4-floroacetophenone, 4-
methoxyacetophenone, benzophenone, 2-acetylbiphenyl,
cyclohexanone, and 3,4-dimethylacetophenone were also in-
vestigated under identical conditions; the results are sum-
2
35
[a]
2
46
[a]
2
CH/HCO
CH/HCO
CH/HCO
CH/HCO
CH/HCO
CH/HCO
CH/HCO
CH/HCO
CH/HCO
CH/HCO
2
H (2.5:2.5)
H (2.5:2.5)
H (2.5:2.5)
H (2.5:2.5)
H (2.5:2.5)
H (2.5:2.5)
H (2.5:2.5)
H (2.5:2.5)
H (2.5:2.5)
H (2.5:2.5)
36
[b]
2
2
02
[
c]
1
0
2
2
56
86
[d]
1
1
2
2
[e]
1
2
2
2
100
[
e]
II
1
3
2
2
74
marized in Table 4. Ru complexes were generally more ef-
[
e]
1
4
2
2
43
ficient catalysts when electron-withdrawing substituents
such as Cl or Br were present at the para or ortho position
of the aryl ring of the ketone. When an electron-donating
substituent such as OCH or CH was introduced into the
[
e,f]
1
5
2
2
98
[
a,g]
1
6
1
1
2
2
90
[
e,g]
16
2
2
94
3
3
[
a] Method B: 1a, 82 °C, H
2
O. [b] Reaction temperature: 25 °C.
O. [f] Com-
aryl ring of the ketone, the catalytic activity decreased. In
the cases of aliphatic ketones, the rate of reaction decreased
even more (entries 10–13).
[c] At 50 °C. [d] At 65 °C. [e] Method C: 2a, 82 °C, H
2
plex 3a was used instead of 2a. [g] Free p-cymene (2.5 mmol) was
added to the aqueous solution.
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H. Türkmen, I˙ . Kani, B. Çetinkaya
FULL PAPER
Table 4. Comparison of the methods for conversion of different 5 equiv. formic acid and sodium formiate to the water phase
substrates.
increased the conversion to 80% within 4 h. This result
demonstrated that complex 1a remains active after the fifth
run.
Table 5. Reusabilty of catalyst 1a for the transfer hydrogenation of
acetophenone using methods B and C.[
a]
Cycles
1st[b] 2nd[b]
3rd[b]
4th[b] 5th[b] 6th[b]
Method B
92
84
54
68
61
–
35 20 (80)[c]
Method C 100
13 (15)[c] (14)[d]
–
–
[
(
8
a] Method B: [S]/[cat]
2.5 mmol/2.5 mmol), H
2 °C, HCO H/HCO Na (2.5 mmol/2.5 mmol), H
Conversion. [c] HCO H/HCO Na (2.5 equiv/2.5 equiv.) was added
=
100, 1a, 82 °C, HCO
O, 4 h; Method C: [S]/[cat] = 100, 2a,
O, 1 min. [b] %
2 2
H/HCO Na
2
2
2
2
2
2
to the water phase. [d] Free p-cymene (2.5 mmol) was added to the
aqueous solution.
In the series of experiments that followed method C, the
reason for this decrease is different. During the second run,
the color of solution turned yellow to green, a phenomenon
that provided evidence of the decomposition of catalyst 2a,
because the addition of hydrogen donor does not afford any
conversion. In addition, the rate of conversion did not
change in the presence of free p-cymene (Table 5).
Conclusion
We have found that ampi is a well-suited bidentate ligand
II
both in cationic and neutral Ru complexes for catalyzing
transfer hydrogenation. The electron-donating ring and the
presence of NH and NH groups increases the yield and
2
solubility in water. It is assumed that this ligand offers extra
hydrogen bonds near the metal center. The synthesis of rho-
dium and iridium complexes with the ampi ligand and chi-
ral versions of ampi and Ts-ampi are in progress in our
laboratories.
[
a] Conversion in %. [b] Method A: [S]/[cat] = 100, 1a, 82 °C, KOH,
IPA, 0.5 h; Method B: [S]/[cat] = 100, 1a, 82 °C, HCO H/HCO Na
2.5 mmol/2.5 mmol), H O, 4 h; Method C: [S]/[cat] = 100, 2a,
2 °C, HCO H/HCO Na (2.5 mmol/2.5 mmol), H O, 1 min.
Experimental Section
2
2
(
8
2
General: Unless otherwise noted, all operations were performed
without taking precautions to exclude air and moisture. All sol-
vents and chemicals were used as received. Starting compounds
and reagents were obtained from Merck, Fluka, Alfa Aesar, and
Acros Organics; 2-aminomethylpiperidine was obtained from Alfa
Aesar; and solvents such as dichloromethane, ethanol, diethyl ether,
toluene, N,N-dimethylformamide, hexane, and pentane were ob-
tained from Merck and Ridel de Haen. Compounds 1e and 1d and
2
2
2
Catalyst Recycling
We examined the possibility of reusing catalysts 1a and
a for the transfer hydrogenation of acetophenone, and the
2
reactions were conducted using method B and method C.
After the first reaction, ethyl ether was added to extract
the organic compounds, and the catalyst immobilized in the
water phase was reused directly. Fresh substrates and suf-
ficient distilled water were added to the water phase that
[
{(p-cymene)RuCl
2
}
2
] were prepared according to the litera-
[13,14]
ture.
Melting points were recorded with a Gallenkamp electro-
thermal melting-point apparatus. Elemental analysis data were re-
corded with CHNS elemental analysis. H and C NMR spectra
were recorded with a Varian AS 400 Mercury instrument. CDCl
1
13
3
contained 1a or 2a to bring the volume to 4.0 mL. The and [D ]DMSO were employed as solvents.
6
yields for the second, third, and fourth cycles were 84, 68,
and 61%, respectively (Table 5). Catalyst 1a appears to be
reusable for four cycles of the transfer hydrogenation of ace-
6
[
0
(η -C10
H
14)Ru(ampi)Cl]Cl (1a): 2-Aminomethylpiperidine (a;
6
.228 g, 2.0 mmol) was added to a suspension of [{(η -C10
RuCl } ] (0.612 g, 1.0 mmol) in dichloromethane (10 mL), and the
2 2
H14)-
tophenone; however, on the fifth cycle, the conversion resulting solution was stirred for 4 h at room temperature. The yel-
dropped to 35%. But after the fifth cycle, the addition of low solution thus obtained was filtered to remove any solid impuri-
4
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Transfer Hydrogenation of Aryl Ketones
ties, and the filtrate was concentrated to half of its volume. The
concentrated solution was saturated with diethyl ether and left in
the refrigerator for crystallization. Slowly, a microcrystalline prod-
uct separated, which was removed by filtration, washed with diethyl
[s, 1 H, C10
3.67 (d, J = 3.1 Hz, 1 H, NCH
{m, 2 H, piperidin-H, C10
H
14(C
6
H
4
)], 5.24 [d, J = 0.9 Hz, 2 H, C10
), 3.12 (m, 1 H, piperidin-H), 2.97
14[CH(CH ]}, 2.85 (m, 1 H, piperidin-
H), 2.37 (m, 1 H, piperidin-H), 2.61 [s, 3 H, p-(CH )C SO ],
2.22 (m, 1 H, piperidin-H), 2.14 [s, 3 H, C10 14(CH )], 1.76–163
)], (m, 2 H, piperidin-H), 1.40 (m, 1 H, piperidin-H), 1.27 {d, J =
)], 5.63 [d, J = 6 Hz, 1 H, 1.8 Hz, 6 H, C10 14[CH(CH ]}, 1.20 {d, J = 3.6 Hz, 6 H,
)], 5.54 [d, J = 5.6 Hz, 1 H, C10 )], 3.39 (d, J 14[CH(CH ]} ppm. C NMR (100 MHz,CDCl ): δ = 139.3,
0.8 Hz, 2 H, NCH ), 3.19 (m, 1 H, piperidin-H), 3.07 {m, 1 139.2, 127.5, 126.6 [p-(CH ], 103.7, 98.2, 83.6, 81.8, 79.1,
14[CH(CH ]}, 2.87 (m,1 H, piperidin-H), 2.72 (m, 1 H, 79.0 [C10 )], 65.4 (NCH ), 54.2, 53.6, 29.7, 27.6, 27.1, 23.8,
piperidin-H), 2.63 (m, H, piperidin-H), 2.50 [s, H, )C SO
14(CH )], 2.21 (m, 1 H, piperidin-H), 1.95 (m, 1 H, piperidin- RuS (574.56):
H), 1.86 (m, 1 H, piperidin-H), 1.60 (m, 2 H, piperidin-H), 1.31
6 4
H14(C H )],
2
H
3 2
)
3
6
H
4
2
1
ether, and dried under vacuum. Yield 0.75 g, 82%. H NMR
H
3
(
5
400 MHz, CDCl
.88 [d, J = 6 Hz, 1 H, C10
3
): δ = 6.27 [d, J = 6 Hz, 1 H, C10
14(C
6 4
H14(C H
H
6
H
4
H
3 2
)
1
3
C
=
10
H14(C
6
H
4
H14(C
6
H
4
C
10
H
3
)
2
3
2
3
)C
6
H
4
SO
2
H, C10
H
3
)
2
6 4
H14(C H
2
1
3
22.0, 20.9, 20.3, 18.7 {piperidin-C, p-(CH
3
6
H
4
2 14
, C10H -
C
10
H
3
[CH(CH ], C10 14(CH )} ppm. C23H34Cl N O
3
)
2
H
3
2 2 2
calcd. C 48.08, H 5.96, N 4.88; found C 48.03, H 5.97, N 4.91.
13
{
(
d, J = 3.6 Hz, 6 H, C10
100 MHz,CDCl ): δ = 103.4, 100.2, 85.9, 83.6, 79.9, 79.0
)], 60.8 (NCH ), 53.2, 50.5, 30.9, 26.5, 26.2, 23.8,
2.3, 18.7 {piperidin-C, C10 14[CH(CH ], C10 14(CH )} ppm.
27Cl Ru (454.83): calcd. C 42.25, H 5.92, N 6.16; found C
3 2
H14[CH(CH ) ]} ppm. C NMR
X-ray Structural Analyses of the Complex: Diffraction data for the
complex were collected with a Bruker SMART APEX CCD dif-
fractometer equipped with a rotation anode at 296(2) K by using
3
[C
10
H
14(C
6
H
4
2
2
C
H
3
)
2
H
3
α
graphite monochromated Mo-K radiation (λ = 0.71073 Å). Dif-
16
H
3 2
N
fraction data were collected over the full sphere and were corrected
for absorption. The data reduction was performed with the Bruker
SAINT[ program package. For further crystal and data collection
details, see Table 1. Structure solution was found with the
42.33, H 5.94, N 6.11.
15]
6
[
(η -C10
H
14)Ru(aquan)Cl]Cl (1c): Compound 1c was prepared by
6
following the procedure for 1a by using [{(η -C10
2 2
H14)RuCl } ]
[16]
SHELXS-97
package by using direct methods refined with
(
0.612 g, 1.0 mmol) and 8-aminoquaniline (0.288 g, 2.0 mmol).
SHELXL-97[ against F , first using isotropic and later aniso-
tropic thermal parameters for all non-hydrogen atoms. Hydrogen
atoms were added to the structure model on calculated positions.
Geometric calculations were performed with Platon.[
17]
2
1
Yield 0.87 g, 89%. H NMR (400 MHz, D
5
7
2
O): δ = 9.48 (d, J =
.2 Hz, 1 H, quaniline-H) 8.42 (d, J = 8.4 Hz, 1 H, quaniline-H),
.80 (d, J = 8.4 Hz, 1 H, quaniline-H), 7.75 (d, J = 7.2 Hz, 1 H,
18]
quaniline-H), 7.65 (dd, J = 3. 6 Hz, 1 H, quaniline-H), 7.57 (t, J =
7
.4 Hz, 1 H, quaniline-H), 5.96 [d, J = 6 Hz, 1 H, C10
H
14(C
6
H
4
)], Hydrogen-Transfer Catalytic Experiments. Method A: Tested com-
5
C
1
.85 [d, J = 6 Hz, 1 H, C10 H )], 5.73 [d, J = 5.6 Hz, 1 H, plex 1 (0.01 mmol) was dissolved in a solution of KOH (1.0 mmol),
H
14(C
)], 5.65 [d, J = 5.6 Hz, 1 H, C10
14[CH(CH ]}, 2.03 [s, 3 H, C10 14(CH
14[CH(CH
O): δ = 156.3, 145.5, 139.6, 138.1, 129.5, 128.7, 128.5, 127.6,
24.3 (quaniline-C), 110.4, 101.1, 85.1, 83.6, 82.9, 82.3
)], 30.6, 21.5, 21.3, 18.0 {C10 14[CH(CH ],
)} ppm. C16 22Cl Ru (454.83): calcd. C 46.97, H
6 4
10
H
H, C10
14(C
6
H
4
6 4
H14(C H )], 2.55 {m, substrate (1.0 mmol), and 2-propanol (4.0 mL) in a Schlenk tube
H
3
)
H
2
H
3
)], 0.98, 0.83 {d, under air. The solution was heated to 82 °C for 0.5 h. The percen-
J = 3.6 Hz, 3 H, C10
D
1
3
)
2
]} ppm. 13C NMR (100 MHz, tage conversion was monitored by H NMR spectroscopy and as
1
2
an average of two trials.
Method B: Complex 1a (0.01 mmol) was dissolved in a solution of
NaO CH (2.5 mmol), HCO H (2.5 mmol), and water (4.0 mL) in
2 2
[C
10
H14(C
6
H
4
H
3 2
)
C
10
H14(CH
3
H
3 2
N
a Schlenk tube under air. Subsequently, substrate (1.0 mmol) was
added with an Eppendorf pipette. The solution was heated to 82 °C
4.56, N 5.77; found C 46.89, H 4.54, N 5.81.
1
Ts-ampi (2): A solution of 2-aminomethylpiperidine (a; 2.28 g,
for 4 h. Percentage conversion was monitored by H NMR spec-
20.0 mmol) and triethylamine (5.7 mL, 40.0 mmol) in dry THF
troscopy and as an average of two trials.
(
20 mL) was cooled to –5 °C. p-Tolylsulfonyl chloride (20.0 mmol)
Method C: Complex 2a (0.01 mmol) was dissolved in a solution of
NaO CH (2.5 mmol), HCO H (2.5 mmol), and water (4.0 mL) in
2 2
was successively added dropwise to the cold solution while main-
taining the reaction temperature below 0 °C. The resulting mixture
was stirred at room temperature for 12 h. The organic layer was
separated and washed with 1 m aqueous H
by saturated aqueous NaHCO (2.5 mL), dried with anhydrous
Na SO , filtered, and concentrated to obtain product 2, which is
a known compound and was fully determined according to the
a Schlenk tube under air. Subsequently, substrate (1.0 mmol) was
added with an Eppendorf pipette. The solution was heated to 82 °C
PO
4
(1.0 mL) followed
1
3
for 1 min. Percentage conversion was monitored by H NMR spec-
3
troscopy and as an average of two trials.
2
4
Recycling Studies with 1a and 2a: The flask was charged with cata-
previously reported data.[ Yield 5.1 g, 95%. H NMR (400 MHz,
CDCl ): 7.86 [d, 8 Hz, H, p-(CH )-
SO ], 7.27 [d, J = 8 Hz, 2 H, p-(CH )C ], 3.65 (d, J =
2.4 Hz, 1 H, NCH ), 3.40–3.35 (m, 2 H, piperidin-H), 3.02 (d, J
12.4 Hz, 1 H, NCH ), 2.91 (m, 1 H, piperidin-H), 2.39 [m, 3 H,
p-(CH )C SO ], 1.98–1.75 (m, 5 H, piperidin-H), 1.47 (m, 1 H,
piperidin-H) ppm. C NMR (100 MHz, CDCl
10]
1
2 2
lyst, acetophenone (1.0 mmol), NaO CH (2.5 mmol), HCO H
(
2.5 mmol), and water (4.0 mL). The solution was heated to 82 °C.
3
δ
=
J
=
2
3
After cooling to room temperature, the organic products were ex-
tracted by using diethyl ether. The aqueous phase was then trans-
ferred to a new reaction flask for the ext cycle. Yields were deter-
C
1
=
6
H
4
2
3
6 4 2
H SO
2
2
1
mined by H NMR spectroscopy for an average of two runs.
3
6
H
4
2
13
): δ = 136.6, 135.2,
CCDC-76046 contains the supplementary crystallographic data for
3
1
29.9, 127.6, [p-(CH
3
)C
6
H
4
SO
2
], 55.6, 45.2, 28.2, 27.4, 23.8, 22.2, this paper. These data can be obtained free of charge from The
SO ] ppm. C13
S (268.37): Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
21.7 [piperidin-C, p-(CH
3
)C
6
H
4
2
20 2 2
H N O
calcd. C 58.18, H 7.51, N 10.44; found C 58.23, H 7.49, N 10.41.
data_request/cif.
6
Synthesis of [(η -C10
H
14)Ru(Ts-ampi)Cl] (2a): Compound 2a was
6
prepared by following the procedure for 1a by using [{(η -C10
RuCl ] (0.612 g, 1.0 mmol) and N-tosyl-2-aminomethylpiperidine
0.536 g, 2.0 mmol). Yield 0.78 g, 68%. H NMR (400 MHz,
CDCl ): δ = 7.64 [d, J = 2 Hz, 2 H, p-(CH )C SO ], 7.06 [d, J 2011-FEN-091) and the Turkish Academy of Sciences (TUBA) is
2 Hz, 2 H, p-(CH )C SO ], 5.75 [s, 1 H, C10 )], 5.46 gratefully acknowledged. We also thank Dr. S. Astley at the Ege
H14)- Acknowledgments
2 2
}
1
(
Financial support from Ege University (project 2010-FEN-046;
3
3
6
H
4
2
=
3
6
H
4
2
6 4
H14(C H
Eur. J. Inorg. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5

Job/Unit: I20638
/KAP1
Date: 27-08-12 18:41:02
Pages: 7
H. Türkmen, I˙ . Kani, B. Çetinkaya
FULL PAPER
University Chemistry Department for reading the manuscript. The
authors are grateful to Anadolu University and the Medicinal
Plants and Medicine Research Centre of Anadolu University, Eski-
s¸ ehir, Turkey, for use of their X-ray diffractometer.
Chem. 2005, 690, 3202–3211; e) J. Canivet, G. Süss-Fink, Green
Chem. 2007, 9, 391–397; f) C. Romain, S. Gaillard, M. K.
Elmkaddem, L. Toupet, C. Fischmeister, C. M. Thomas, J.-L.
Renaud, Organometallics 2010, 29, 1992–1995; g) I. Nieto,
M. S. Livings, J. B. Sacci, L. E. Reuther, M. Zeller, Organome-
tallics 2011, 30, 6339–6342.
[9] a) W. Baratta, K. Siega, P. Rigo, Chem. Eur. J. 2007, 13, 7479–
[
1] a) S. Hashiguchi, A. Fujii, J. Takehara, T. Ikariya, R. Noyori,
J. Am. Chem. Soc. 1995, 117, 7562–7563; b) A. Fujii, S. Hashig-
uchi, N. Uematsu, T. Ikariya, R. Noyori, J. Am. Chem. Soc.
7
486; b) A. Del Zotto, C. Greco, W. Baratta, K. Siega, P. Rigo,
Eur. J. Inorg. Chem. 2007, 2909–2916; c) W. Baratta, K. Siega,
P. Rigo, Adv. Synth. Catal. 2007, 349, 1633–1636; d) W. Ba-
ratta, M. Ballico, S. Baldino, G. Chelucci, E. Herdtweck, K.
Siega, S. Magnolia, P. Rigo, Chem. Eur. J. 2008, 14, 9148–9160;
e) W. Baratta, F. Benedeti, A. Del Zotto, L. Fanfoni, F. Felluga,
S. Magnolia, E. Putignano, P. Rigo, Organometallics 2010, 29,
3563–3570; f) W. Baratta, G. Bossi, E. Putignano, P. Rigo,
Chem. Eur. J. 2011, 17, 3474–3481; g) S. Günnaz, N. Özdemir,
S. Dayan, O. Dayan, B. Çetinkaya, Organometallics 2011, 30,
4165–4173.
1
996, 118, 2521–2522; c) J. Takehara, S. Hashiguchi, A. Fujii,
S. Inoue, T. Ikariya, R. Noyori, Chem. Commun. 1996, 233–
34.
2] a) R. Noyori, S. Hashiguchi, Acc. Chem. Res. 1997, 30, 97–
2
[
1
2
1
02; b) S. Gladiali, E. Alberico, Chem. Soc. Rev. 2006, 35, 226–
36; c) T. Ikariya, A. J. Blacker, Acc. Chem. Res. 2007, 40,
300–1308.
[
3] a) S. E. Clampham, A. Hadzovic, R. H. Morris, Coord. Chem.
Rev. 2004, 248, 2201–2237; b) J. S. M. Samec, J. E. Backvall,
P. G. Andersson, P. Brandt, Chem. Soc. Rev. 2006, 35, 237–248.
4] a) S. Ogo, T. Abura, Y. Watanabe, Organometallics 2002, 21,
[10] O. Froelich, M. Bonin, J.-C. Quirion, H.-P. Husson, Tetrahe-
dron: Asymmetry 1993, 4, 2335–2338.
[
[11] a) Y. Miyaki, T. Onishi, H. Kurosawa, Inorg. Chim. Acta 2000,
300–302, 369–377; b) P. Pinto, A. W. Götz, G. Marconi, B. A.
Hess, A. Marinetti, F. W. Heinemann, U. Zenneck, Organome-
tallics 2006, 25, 2607–2616; c) Y. Ura, M. Masashi, K. Sa-
daoka, T. Suziki, T. Kondo, T. Mitsudo, Organometallics 2003,
22, 1863–1867; d) C. Menéndez, D. Morales, J. Pérez, V. Riera,
Organometallics 2001, 20, 2775–2781; e) M.-L. Le haire, R.
Scopelliti, L. Herdeis, K. Polborn, P. Mayer, K. Severin, Inorg.
Chem. 2004, 43, 1609–1617; f) R. Lalrempuia, M. R. Kollipara,
P. J. Carroll, G. P. A. Yap, K. A. Kreisel, J. Organomet. Chem.
2005, 690, 3990–3996.
[12] a) R. Stodt, S. Gencaslan, I. M. Müller, W. S. Sheldrick, Eur.
J. Inorg. Chem. 2003, 1873–1882; b) P. Haquette, B. Talbi, S.
Canaguier, S. Dagorna, C. Fosse, A. Martel, G. Jaouen, M.
Salmain, Tetrahedron Lett. 2008, 49, 4670–4673; c) A. Cabal-
lero, F. Jalon, B. R. Manzano, G. Espino, M.-P.-M. A.
Mcientes, F. J. Poblete, M. Maestro, Organometallics 2004, 23,
5694–5706.
2
2
2
964–2969; b) X. Fu, J. Xiao, Chem. Commun. 2007, 2449–
466; c) A. Robertson, T. Matsumoto, S. Ogo, Dalton Trans.
011, 40, 10304–10310.
[
5] J. Canivet, G. Lapat, H. Stoeckli-Evans, G. Süss-Fink, Eur. J.
Inorg. Chem. 2005, 4493–4500.
[
6] a) W. Baratta, G. Chelucci, S. Gladiali, K. Siega, M. Toniutti,
M. Zanette, E. Zangrando, P. Rigo, Angew. Chem. 2005, 117,
6
370; Angew. Chem. Int. Ed. 2005, 44, 6214–6219; b) W. Ba-
ratta, E. Herdtweck, K. Siega, M. Toniutti, P. Rigo, Organome-
tallics 2005, 24, 1660–1669; c) A. Del Zotto, W. Baratta, M.
Ballico, E. Herdtweck, P. Rigo, Organometallics 2007, 26,
5636–5642.
[
7] a) A. C. Hillier, H. M. Lee, E. D. Stevens, S. P. Nolan, Organo-
metallics 2001, 20, 4246–4252; b) H. Türkmen, T. Pape, F. E.
Hahn, B. Çetinkaya, Organometallics 2008, 27, 571–575; c) H.
Türkmen, T. Pape, F. E. Hahn, B. Çetinkaya, Eur. J. Inorg.
Chem. 2008, 5418–5423; d) S. Gülcemal, J.-C. Daran, B. Çetin-
kaya, Inorg. Chim. Acta 2011, 365, 264–268; e) W. N. O. Wylie,
A. J. Lough, R. H. Morris, Organometallics 2012, 31, 2137–
[13] M. A. Bennett, A. K. Smith, J. Chem. Soc., Dalton Trans. 1974,
233.
2
151; f) I. Özdemir, S. Ya s¸ ar, B. Çetinkaya, Transition Met.
[14] R. R. Dykeman, K. L. Luska, M. E. Thibault, D. Jones, M.
Schlaf, M. Khanfar, N. J. Taylor, J. F. Britten, L. Harrington,
J. Mol. Catal. A 2007, 277, 233–251.
Chem. 2005, 30, 831–835; g) M. Yigit, B. Yigit, I. Özdemir, E.
Çetinkaya, B. Çetinkaya, Appl. Organomet. Chem. 2006, 20,
3
22–327; h) N. Gürbüz, S. Ya s¸ ar, E. Ö. Özcan, I. Özdemir, B.
[15] SMART, Bruker AXS, 2000.
Çetinkaya, Eur. J. Inorg. Chem. 2010, 3051–3056; i) N. Gürbüz,
E. Ö. Özcan, I. Özdemir, B. Çetinkaya, O. S¸ ahin, O.
Büyükgüngör, Dalton Trans. 2012, 41, 230–239.
[16] SHELXS-97: G. M. Sheldrick, Acta Crystallogr., Sect. A 1990,
46, 467.
[17] G. M. Sheldrick, SHELXL-97, Universität Göttingen, Ger-
many, 1997.
[8] a) Y. Ma, H. Liu, L. Chen, X. Cui, J. Zhu, J. Deng, Org. Lett.
2
003, 5, 2103–2106; b) X. Wu, X. Li, W. Hems, F. King, J.
[18] a) A. L. Spek, Platon-A Multipurpose Crystallographic Tool,
Utrecht University, The Netherlands, 2005.
Xiao, Org. Biomol. Chem. 2004, 2, 1818–1821; c) X. Wu, D.
Vinci, T. Ikariya, J. Xiao, Chem. Commun. 2005, 4447–4449; d)
J. Canivet, L. Karmazin-Brelot, G. Süss-Fink, J. Organomet.
Received: June 12, 2012
Published Online: ᭿
6
www.eurjic.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 0000, 0–0

Job/Unit: I20638
/KAP1
Date: 27-08-12 18:41:02
Pages: 7
Transfer Hydrogenation of Aryl Ketones
Arene–Ruthenium(II) Complexes
˙
H. Türkmen,* I. Kani,
∧
A
series of N N complexes of ru-
thenium(II) have been isolated and struc-
turally characterized. These complexes
were found to be amenable catalysts for the
transfer hydrogenation of ketones.
B. Çetinkaya ..................................... 1–7
Transfer Hydrogenation of Aryl Ketones
II
with Half-Sandwich Ru Complexes That
Contain Chelating Diamines
Keywords: Hydrogenation / Ruthenium / N
ligands / Ketones / Arenes
Eur. J. Inorg. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
7