Piano-stool benzothiazol-2-ylidene Ru(II) complexes for effective transfer hydrogenation of carbonyls

Article abstract of DOI:10.1016/j.jorganchem.2016.02.003

Benzothiazolium bromides (NSHC.HBr) (1a-j) with a variety of alkyl chain or benzyl substituents on N atom were prepared. The synthesis of ruthenium(II) (NSHC) complexes, (2a–j) could be achieved by in situ deprotonation of benzothiazolium salts with Ag₂O and [RuCl₂(p-cymene)]₂. They were characterized by ¹H, ¹³C, ¹⁹F NMR, IR spectroscopy and elemental analysis. The molecular structures of 2d, 2e and 2g were ascertained by single-crystal X-ray diffraction studies. The catalytic properties of complexes, (2a–j), with electron-donating or -withdrawing groups were investigated in transfer hydrogenation (TH) of ketones, and aldehydes with good to excellent yields. The presence of the CH₂(CH₂)₁₆CH₃ or CH₂C₆F₅ on the N atom of the benzothiazol-2-ylidene complexes (2g, 2j) showed the highest activity for TH reaction. The catalytic properties of the N-alkyl substituted ruthenium(II) (NSHC) complexes(2h–j) may be interpreted by micelle effects.

Full text of DOI:10.1016/j.jorganchem.2016.02.003

Accepted Manuscript
Piano-Stool Benzothiazol-2-ylidene Ru(II) Complexes for Effective Transfer
Hydrogenation of Carbonyls
Zeynep İpek Oruç, Lütfiye Gök, Hayati Türkmen, Onur Şahin, Orhan Büyükgüngör,
Bekir Çetinkaya
PII:
S0022-328X(16)30036-5
10.1016/j.jorganchem.2016.02.003
JOM 19387
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 2 December 2015
Revised Date: 29 January 2016
Accepted Date: 1 February 2016
Please cite this article as: Z.İ. Oruç, L. Gök, H. Türkmen, O. Şahin, O. Büyükgüngör, B. Çetinkaya,
Piano-Stool Benzothiazol-2-ylidene Ru(II) Complexes for Effective Transfer Hydrogenation of Carbonyls,
Journal of Organometallic Chemistry (2016), doi: 10.1016/j.jorganchem.2016.02.003.
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ACCEPTED MANUSCRIPT
Piano-Stool Benzothiazol-2-ylidene Ru(II) Complexes for Effective Transfer
Hydrogenation of Carbonyls
Zeynep İpek Oruç, Lütfiye Gök, Hayati Türkmen,* Onur Şahin, Orhan Büyükgüngör, Bekir
Çetinkaya
R
a
b
c
d
e
f
IPA
KOH
g
h
i
2a-i
2c < 2e < 2d ≈ 2a < 2b < 2f < 2h < 2i < 2g

ACCEPTED MANUSCRIPT
Piano-Stool Benzothiazol-2-ylidene Ru(II) Complexes for Effective Transfer
Hydrogenation of Carbonyls
Zeynep İpek Oruç,a Lütfiye Gök,a Hayati Türkmen,a* Onur Şahin,b Orhan Büyükgüngör,c
Bekir Çetinkaya,a
aDepartment of Chemistry, Ege University, 35100, Bornova-Izmir, Turkey
bScientific and Technological Research Application and Research Center, Sinop University,
57010, Sinop, Turkey
cDepartment of Physics, Faculty of Arts and Sciences, Ondokuz Mayis University, Samsun,
Turkey
ABSTRACT: Benzothiazolium bromides (NSHC.HBr) (1 a-j) with a variety of alkyl chain or
benzyl substituents on N atom were prepared. The synthesis of ruthenium(II) (NSHC)
complexes, (2a-j) could be achieved by in situ deprotononation of benzothiazolium salts with
1
Ag2O and [RuCl2(p-cymene)]2. They were characterized by H-, 13C-, 19F-NMR, IR
spectroscopy and elemental analysis. The molecular structures of 2d, 2e and 2g were
ascertained by single-crystal X-ray diffraction studies. The catalytic properties of complexes,
(2a-j), with electron-donating or -withdrawing groups were investigated in transfer
hydrogenation (TH) of ketones, and aldehydes with good to excellent yields. The presence of
the CH2(CH2)16CH3 or CH2C6F5 on the N atom of the benzothiazol-2-ylidene complexes (2g,
2j) showed the highest activity for TH reaction. The catalytic properties of the N-alkyl
substituted ruthenium(II) (NSHC) complexes(2h-j) may be interpreted by micelle effects.
Keywords: Benzothiazolium salts, NSHC-Ru(II) complexes, the transfer hydrogenation,
catalysis.
INTRODUCTION
The chemistry of Ru(II) stabilized by NHC ligands, in particular imidazole(in) ylidenes have
attracted much interest due to their catalytic applications. However, compared to NNHC
chemisrty, NSHC coordinated to Ru are less developed. The first complexes of N,S-
heterocyclic carbenes (NSHC) derived from the electron-rich aminoalkenes were reported by
Lappert et. al.[1] Later, similar complexes were prepared from lithiated thiazoles.[2] Arduengo
described the first stable thiazol-2-ylidene and its dimer in 1997.[3] The benzothiazol-2-
ylidene Pd(II) complexes and their catalytic applications in C-C reaction were investigated by
1

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Calo et al. [4] More recently, their Ni(II), [5] Cu(I), [6] Au(I), [7] Au(III), [8] Pd(II),[4,9] Ir(I), [10]
[11]
Pt(II)
complexes were prepared from direct or indirect metallation methods. Hor et al.
synthesized benzothiazol-2-ylidene Ru(II)(phosphine) complexes from [Ru(OAc)2(PPh3)3]
and benzothiazolium salts. The resulting complexes were used as catalysts for TH reactions of
[12]
polar substrates such as ketones from hydrogen donors such as 2-propanol (IPA).
The
ligands applied to TH feature various combinations of nitrogen, phosphorus, arene and N-
heterocyclic carbene carbon as donor atoms. [13-17] More recently, we demonstrated that the
NHC complexes bearing various N-benzyl substituents were more active catalysts for
reduction of ketones.[17b-c] Here we describe our effort to enhance activity of NNHC
complexes by incorporation of NSHC ligands. However, compared to NNHC chemistry,
NSHC coordinated to Ru are underdeveloped.
RESULTS AND DISCUSSION
Synthesis of salts and ruthenium(II) complexes
The benzothiazolium salts (1) were synthesized by the reaction of benzyl or alkyl bromides
and benzothiazole (Scheme 1). These salts are air and moisture stable pale yellow-crystaline
solids. The IR data for these salts (1a-j) clearly indicated the presence of the –C=N– group
with υ(C=N) vibrations between 1591-1666 cm-1. They have been characterized by 1H and 13C
1
NMR spectroscopy. The H NMR spectra of these salts were consistent with the proposed
13
structures; C2-H resonances displayed at δ 9.56-10.84 ppm as sharp singlet and C NMR of
these salts showed the C2-H carbons at δ 157.0-165.7 ppm.
Scheme 1. Synthesis and reactions of benzothiazolium salts (1a-i).
R
a
b
c
d
e
f
g
h
ı
i
-(CH2)6CH3
-(CH2)10CH3
j
When the reaction of Ag2O with 1a-j was carried out in the presence of [RuCl2(p-
cymene)]2 at 25 °C (Scheme 1), the desired products(2a-j) were obtained in good yields (61-
2

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70%) (Table 1). It is worth noting that we were unable to access the intermediate Ag(NSHC)
complexes. These Ru(II) complexes are air and moisture stable and red-brown crystals which
have been characterized by spectroscopy and elemental analysis. The IR data for these
complexes (2a-j) clearly indicated the presence of the –C=N– group with a υ(C=N) vibrations
between 1604-1666 cm-1. 13C NMR of the complexes showed the C2 carbons at δ 223.8-230.8
ppm (Table 1).
Table 1. Melting points, yields and selected 1H NMR, 13C NMR data of 2a-j.
Entry
Comp.
Yield(%)
υ(C N)(cm-1)
CH2-1H NMR CH2-13C NMR
C2-13C NMR
m.p.(°C)
1
67
65
70
64
68
61
65
68
63
65
64
120-121
189-191
208-210
210-212
179-181
186-188
182-184
175-177
170-172
174-176
180-182
1604.4
1643.8
1611.4
1651.3
1634.7
1621.0
1665.8
1654.5
1654.0
1654.2
1590.1
6.36
6.22
6.35
6.45
6.44
6.43
6.45
5.30
5.29
5.30
5.45
57.0
56.9
55.8
55.9
57.7
57.1
49.6
54.6
54.5
54.6
54.8
227.3
227.4
225.8
223.8
224.7
230.8
229.8
224.2
224.1
224.2
224.3
2a
2b
2c
2d
2e
2f
2
3
4
5
6
7
2g
2h
2ı
8
9
10
11
2i
2j
The molecular structures of 2d, 2e, 2g with the atom numbering schemes are shown in
Figure 1. The crystallographic analyses revealed that the complexes 2d, 2e and 2g appear very
similar. The asymmetric units of 2d, 2e and 2g consists of two Ru(II) complex. Also the
asymmetric unit of 2d consists of one ethanol molecule, whereas the asymmetric unit of 2e
consists of two ethanol molecules. Each Ru(II) ion is coordinated by one carbon atom [C(11)
and C(40)] of carbene ligand, one p-cymene ligand and two chlorine atoms [Cl(1), Cl(2),
Cl(3) and Cl(4)]. The Ru-Cl bond distances ranged between 2.4207(15)-2.4515(15) Å in 2d,
2.422(2)-2.437(4) Å in 2e and 2.4114(16)-2.4323(17) Å in 2g, respectively (Table 2). The Ru-
C bond distances [2.043(6) and 2.062(6) Å in 2d, 2.077(13) and 2.044(19) Å in 2e and
2.034(6) and 2.026(6) Å in 2g, respectively] are comparable to those reported for the
corresponding Ru(II) complexes. The Cl-Ru-Cl bond angles are 87.93(5)° and 88.28(5)º in
2d, 87.23(10)° and 88.82(16)° in 2e and 88.61(6)° and 87.66(6)° in 2g, respectively. The N-
C-S bond angles are 108.7(4)° and 109.8(4)° in 2d, 110.2(9)° and 108.2(13)° in 2e and
107.8(4)° and 107.9(4)° in 2g, respectively.
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4

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Figure 1. The molecular structure of respectively 2d , 2e , 2g
Table 2. Selected bond lengths (Å) and angles (°) for 2d, 2e and 2g.
2d
2.043 (6)
2.4287 (15)
2.4515 (15)
1.738 (7)
87.93 (5)
88.16 (16)
108.7 (4)
2.4207 (15)
2.4446 (15)
2.062 (6)
1.331 (7)
1.727 (6)
91.77 (17)
86.98 (18)
109.8 (4)
1.742 (8)
1.734 (6)
1.343 (7)
88.28 (5)
91.48 (16)
2e
2.077 (13)
2g
C11-Ru1
Cl1-Ru1
Cl2-Ru1
C17-S1
Cl1-Ru1-Cl2
C11-Ru1-Cl2
N1-C11-S1
Cl3-Ru2
Cl4-Ru2
C40-Ru2
C40-N2
C40-S2
C40-Ru2-Cl3
C40-Ru2-Cl4
N2-C40-S2
C45-S2
C11-S1
C11-N1
Cl3-Ru2-Cl4
C11-Ru1-Cl1
2.034 (6)
2.4114 (16)
2.4232 (15)
1.722 (6)
88.61 (6)
85.26 (15)
107.8 (4)
2.4154 (17)
2.4323 (17)
2.026 (6)
1.361 (6)
1.720 (6)
84.60 (16)
92.75 (17)
107.9 (4)
1.726 (6)
1.715 (6)
1.358 (6)
87.66 (6)
92.46 (16)
2.422 (2)
2.423 (3)
1.729 (13)
87.23 (10)
87.3 (3)
110.2 (9)
2.432 (4)
2.437 (4)
2.044 (19)
1.33 (2)
1.753 (16)
92.4 (4)
86.7 (4)
108.2 (13)
1.73 (2)
1.687 (12)
1.362 (14)
88.82 (16)
91.9 (4)
5

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Table 3. Crystal data and structure refinement parameters for complexes.
2d
C58H72Cl4N2ORu2S2
1221.24
2e
C31H41Cl2NORuS
647.68
2g
C24H20Cl2F5NRuS
621.44
Empirical formula
Formula weight
Temperature, K
Wavelength, Å
Crystal system
Space group
a, Å
296
0.71073
Triclinic
296
0.71073
296
0.71073
Trigonal
P-3
36.4786 (13)
36.4786 (13)
6.3596 (2)
90.00
90.00
120.00
7328.9 (3)
Monoclinic
P21/c
15.1317 (5)
17.1387 (7)
25.5028 (8)
90.00
105.649 (2)
90.00
6368.7 (4)
P-1
12.7478 (5)
14.0010 (5)
17.8750 (7)
106.496 (3)
98.465 (4)
97.898 (3)
2971.2 (2)
b, Å
c, Å
α, °
β, °
γ, °
3
Volume, Å
Z
2
8
12
3
1.365
1.351
1.690
D (calcd), Mg/m
-1
0.80
0.75
1.00
Abs. coeff., mm
F(000)
1260
2688
3720
3
0.37 × 0.18 × 0.06
0.28 × 0.21 × 0.15
0.38 × 0.18 × 0.07
Crystal size, mm
Theta range, °
Reflts collected
R(int)
1.8–28.1
28427
0.061
1.2–27.4
48560
0.112
1.1–25.2
41806
0.122
Abs. correction
Max. / min. abs.
Data / restr. / param.
Integration
0.936/0.534
11672/9/624
0.97
Integration
0.912/0.832
11848/14/675
1.06
Integration
0.903/0.605
8245/12/614
0.72
2
GOOF on F
R , wR2 [I>2\s(I)]
R , wR2 (all data)
0.058/0.130
0.103/0.147
1.36/−0.70
0.115/0.298
0.186/0.344
3.63/-2.35
0.041/0.049
0.125/0.059
0.59/-0.47
-3
Resid. density, e.Å
Catalytic activity
We have evaluated the catalytic efficiency of complexes 2 in TH of ketones and aldehydes.
The data obtained were compared with the previously reported complexes. The catalytic
reactions were performed under identical conditions to allow comparasion of the results. To
investigate the influence of auxiliary ligands on catalytic activity of Ru(II) complexes (2a-j)
the time dependency was studied using 1%[Ru] in 2-PrOH with KOH as the base at 82 °C
(Figure 2). As can be seen from Figure 2, the complexes (2a-j) were found to be active
catalyst in transfer hydrogenation of acetophenone, and benzaldehyde. The complexes 2g and
2j were found to be the most active catalysts among all of these complexes. For example,
after 30 min, a 93% conversion and after 90 min, a 97% conversion and after 120 min, a
100% conversion was achieved for the conversion of 1-phenylethanol, using complex 2g. On
the other hand, the activity decreased as number of methyl substituents on benzyl substituent
6

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increased. The presence of C6F5 or long alkyl substituents on N-atom increased the rate of the
transfer hydrogenation. The sequence of the activity is 2g > 2j >2i >2ı > 2h > 2f > 2b > 2a ≈
2d > 2e > 2c. The ruthenium complexes bearing NSHC ligand with N-benzyl substituent were
reported to show a good catalytic activity, [12] which was however significantly lower than
that of 2g. In fact 1% mol catalyst 24 h of reaction time were required conversions obtainable
with 1% mol of 2g with in 1h. As mentioned above, these results revealed that 2g, 2j were the
most active, whereas the complexes 2b, 2c, 2d, 2e with the electron donating substituents,
were significantly less active under the reaction conditions employed. The sluggish activity of
2b, 2c, 2d and 2e may be related to their propensity to afford η6-tethered complexes in which
p-cymene ligand replaced by the aryl of the benzyl substituent. In order to test this hypothesis,
we heated the 2-PrOH solution of 2e. A red-orange precipitate of 3e was formed after 2 h
heating at 82 °C. Purified η6-tethered complex 3e (Scheme 2) [18] was used as precatalyst, 2-
phenylethanol in 20% yield, which is clearly lower than that of 2e (Table 3, entries 1 and 2).
These observations are consistent with finding by Papish et al. [19] They showed that the TH
reaction initates by arene ligand dissociation to open a free coordination site. Besides, Müller
and co-workers prepared a number of the tethered and nontethered Ru(II) complexes bearing
the P-stereogenic phosphines and examined their excellent ability to catalyze the reduction of
acetophenone. [20]
Scheme 2. Synthesis of the complex 3e.
Figure 2. Time dependency of the catalytic TH of acetophenone (left) and benzaldehyde (right) catalyzed by the
complexes (2a-j)
100
80
60
40
20
0
100
80
60
40
20
0
5
15
30
60
90
120
5
15
30
60
90
120
Time (min.)
Time (min.)
7

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We also surveyed the effect of the bases, the catalyst loading, temperature and solvents on the
TH of acetophenone by using ruthenium complexes(Table 4). As in the previous studies the
best results were obtained with KOH and KOBut among the bases investigated in TH. [17] In
the absence of a base no TH reaction of ketone was observed (Entry 7). When the catalyst
loading decreased, a slightly lower yield was obtained (Entries 8 and 9). Among the solvents
explored (EtOH, MeOH), the best result was obtained in IPA. To test the effect of
temperature on catalyst 2g performance, the catalytic reaction was performed at 50 °C (Entry
11). The yield was dropped from 96 % to 46% (Entries 3 and 11).
Table 4. Screening of reaction conditions, for 2e, 3e and 2g.
Entry
cat
mol%
solvent
base
temprature (°C)
conversion(%)
1
2
1
1
IPA
IPA
KOH
KOH
KOH
NaOH
KOBut
K2CO3
-
82
82
82
82
82
82
82
82
82
82
82
50
36
22
96
85
95
61
-
2e
3e
2g
2g
2g
2g
2g
2g
2g
2g
2g
2g
3
1
IPA
4
1
IPA
5
1
IPA
6
1
IPA
7
1
IPA
8
0.1
0.01
1
IPA
KOH
KOH
KOH
KOH
KOH
80
33
8
9
IPA
10
11
12
EtOH
MeOH
IPA
1
11
6
1
[RuCl2( p-
cymene)]2
13
0.5
IPA
KOH
82
9
The most effective catalyst 2a, 2g and 2j were used in TH of different ketones and
aldehydes to investigate the scope of the reaction (Table 5). It was observed that electron-
withdrawing groups in the para position of acetophenone increased the yield whereas electron
donating groups at para position of acetophenone decreased the yield slightly. In addition the
catalyst 2g and 2j were effective for the reduction of not only aromatic ketones but also
aliphatic ketones. On the other hand, catalysts 2j and 2i, bearing a long alkyl chain on ligand,
may favor the formation of metallomicelles, leading to strongly hydrophobic interaction
[21]
between the chain of the catalyst and the alkyl chain of the substrate in the core.
8

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Therefore, synergistic effects between the metal-catalyzed center and substrate facilitate the
reduction.
Table 5. The catalytic TH of different ketones and aldehydes catalyzed by the Ru (II) complexes
Entry [Ru]
Substrate
Product
Time(h) Yield(%)a
1
2
3
4
5
6
2-chloroacetophenone
4-chloroacetophenone
4-bromoacetophenone
4-methoxyacetophenone
3,4-dimethylacetophenone
2-heptanone
1-(2-chlorophenyl)ethanol
1-(4-chlorophenyl)ethanol
1-(4-bromophenyl)ethanol
1-(4-methoxyphenyl)ethanol
1-(3,4-dimethylphenyl)ethanol
heptan-2-ol
1
0.5
0.5
1
58
96
2g
2g
2g
2g
2g
2g
100
100
84
1
1
80
7
8
9
4-methyl-4-methylthio-2-pentanone
2-heptanone
4-methyl-4-(methylthio)pentan-2-ol
heptan-2-ol
0.5
1
100
100
100
2g
2j
2j
4-methyl-4-methylthio-2-pentanone
4-methyl-4-(methylthio)pentan-2-ol
0.5
10
11
12
13
14
15
16
17
Cyclohexanone
Cyclohexanone
cyclohexanol
cyclohexanol
2
2
100
85
2j
2a
2j
Benzophenone
diphenylmethanol
4
66
Benzophenone
diphenylmethanol
4
45
2a
2g
2g
2g
2g
4-chlorobenzaldehyde
4-bromobenzaldehyde
4-methoxybenzaldehyde
2,3,4,5,6-pentafluorobenzaldehyde
(4-chlorophenyl)methanol
(4-bromophenyl)methanol
(4-methoxyphenyl)methanol
(perfluorophenyl)methanol
0.5
0.5
0.5
0.5
100
100
87
100
aReaction conditions: substrate (1.5 mmol), [Ru] (0.01 mmol), KOH (0.15 mmol), 1.5 mL, 2-propanol 18.5 mL.
In a separate experiment to assess whether the reaction system is homogeneous or
heterogeneous, Hg(0) and 1,10-phenantroline poisoning tests were carried out(Table 5). The
suppression of catalysis by Hg(0) is evidence for a heterogeneous catalyst; if Hg(0) does not
suppress catalysis, that is evidence for a homogeneous catalyst. [22] The poisoning tests with
Hg(0) and 1,10-phenantroline of catalyst 2j for the catalytic TH of acetophenone to 1-
phenylethanol in basic IPA showed no significant inhibition of conversion to products. A
9

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negative results for the Hg(0) and 1,10-phenantroline poisoning tests can confirm a
homogeneous catalytic system.
Table 6. The poisoning tests with mercury(0) and 1,10-phenantroline for the catalytic TH of acetophenone to 1-
phenylethanol in IPA with the complex 2j.
Entry
2j:Hg
Time (h)
0.5:1
yield(%)a
75:80
1
2
3
1:0
1:1
0.5:1
70:82
1:300
0.5:1
63:74
2j:1,10-phenantroline
4
5
6
1:0
1:1
0.5:1
0.5:1
0.5:1
75:80
24:27
7:7
1:100
aReaction conditions: substrate (1.5 mmol), [2j] (0.01 mmol), KOH (0.15 mmol), 1.5 mL, 2-propanol 18.5 mL.
CONCLUSION
Nine new Ru(II) complexes bearing (p-cymene) and NSHC ligands have been made with a
variety of N-alkyl substituents by one-step reaction of benzothiazolium bromide, Ag2O and
o
[(p-cymene)RuCl2]2 at 25 C. The catalytic properties of complexes (2a-j) were examined in
transfer hydrogenation reaction of ketones and aldehydes. It is clear that the introduction of
the CH2C6F5 and a long chain group to nitrogen atom increased TH performance, even more
efficient than the related Ru(NSHC) complex. [12] These observations may be interpreted that
electronic influences and micele effects of the NSHC respectively.
EXPERIMENTAL SECTION
General Consideration. Unless otherwise noted all manipulations were performed in
air. Reactions involving air-sensitive components were performed by using Schlenk-type flask
under argon atmosphere and high vacuum-line techniques. The glass equipment was heated
under vacuum in order to remove oxygen and moisture and then they were filled with argon.
The solvents were analytical grade and distilled under argon atmosphere from sodium (diethyl
10

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1
13
ether, ethylacetate, dimethylformamide). H NMR and C NMR spectra were recorded on a
Varian AS 400 Mercury instrument.
Crystallographic data collection and refinement. Diffraction experiments were
carried out at 296 K on a Stoe IPDS diffractometer. The structures were solved by direct
methods and refined using the programs SHELXS97 and SHELXL97. [23] All non-hydrogen
atoms were refined anisotropically by full-matrix least squares methods All hydrogen atoms
bonded to C and O atoms were refined using a riding model, with C–H = 0.93-0.98 Å and O–
H = 0.82 Å. The following procedures were implemented in our analysis: data collection: X-
Area, cell refinement: X-Area, data reduction: X-RED[24]; program(s) used for molecular
graphics were as follows: Mercury programs25; software used to prepare material for
publication: WinGX. [26]
Synthesis of Benzothiazolium Salts (1b-j). The bromide 1a was prepared according to
the literature method. Benzothiazole (1.0 g; 7.40 mmol) was dissolved in DMF (10 mL) and
o
alkyl bromide (7.40 mmol) was added. The mixture was stirred for 2 h at 60 C. The pale
yellow solid that separated out after cooling was filtered off and washed with diethyl ether (20
mL). The product (1a) was recrystallized from CH2Cl2/Et2O. The following salts (1b-j) were
synthesized according to this procedure.
0
1b; Yield: 1.92 g, 81%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ 10.78 (s, 1H,
NCHS), 8.54 (d, 1 H, JHH = 8.0 Hz, Ar-H), 8.31 (d, 1H, JHH = 8.0 Hz, Ar-H), 7.84 (m, 4H,
CH2C6H4(CH3)), 7.42 (d, 1H, JHH = 8.0 Hz, Ar-H), 7.21 (d, 1H, JHH = 8.0 Hz, Ar-H), 6.10 (s,
13
0
2H, CH2C6H4(CH3)), 2.62 (m, 3 H, CH2C6H4(CH3)). C NMR (100.6 MHz, DMSO, 25 C,
ppm): δ 165.7 (NCS), 140.7, 139.2, 132.5, 130.4, 130.3, 130.2, 129.4, 129.1, 126.1, 118.1
(Ar-C, CH2C6H4(CH3)), 55.8 (CH2C6H4(CH3)), 21.4 (CH2C6H4(CH3)). Anal. Calc. for
C15H14BrNS (M = 320.25): C, 56.26; H, 4.41; N, 4.37; Found: C, 56.31; H, 4.49; N, 4.42.
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1c; Yield: 2.16 g, 84%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ 9.65 (s, 1 H,
NCHS), 8.57 (d, 1 H, JHH = 8.6 Hz, Ar-H), 8.00 (d, 1 H, JHH = 8.6 Hz, Ar-H), 7.96 (s, 2 H,
CH2C6H2(CH3)3), 7.90 (m, 2 H, Ar-H), 5.93 (s, 2 H, CH2C6H2(CH3)3), 2.48 (s, 3 H,
0
CH2C6H2(CH3)3), 2.49 (s, 6 H, CH2C6H2(CH3)3). 13C NMR (100.6 MHz, DMSO, 25 C,
ppm): δ 162.8 (NCS), 146.9, 138.7, 136.8, 136.2, 132.3, 130.7, 129.7, 129.0, 128.7, 128.6
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(Ar-C, CH2C6H2(CH3)3), 41.1 (CH2C6H4(CH3)3), 21.2, 19.0 (CH2C6H2(CH3)3). Anal. Calc.
for C17H18BrNS (M = 348.30): C, 58.62; H, 5.21; N, 4.02; Found: C, 58.69; H, 5.28; N, 4.11.
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1d; Yield: 2.38 g, 89%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ = 9.56 (s, 1H,
NCHS), 8.64 (d, 1H, JHH = 8.8 Hz, Ar-H), 8.56 (d, 1H, JHH = 7.6 Hz, Ar-H), 8.05 (m, 1H, Ar-
H), 7.93 (m, 1H, Ar-H), 7.21 (s, 1H, CH2C6H(CH3)4, Ar-H), 5.99 (s, 2H, CH2C6H(CH3)4),
2.51, 2.27, 2.13 (m, 12H, CH2C6H(CH3)4). 13C NMR (400 MHz, DMSO): δ 162.8 (NCS),
147.0, 136.1, 134.9, 133.5, 133.4, 132.5, 131.4, 129.5, 128.6, 128.5 (Ar-C, CH2C6H(CH3)4),
41.8 (CH2C6H(CH3)4), 20.8, 15.7 (CH2C6H(CH3)4). Anal. Calc. for C18H20BrNS (M =
362.33): C, 59.67; H, 5.56; N, 3.87; Found: C, 60.11; H, 5.72; N, 3.55.
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1e; Yield: 2.33 g, 84%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ = 9.59 (s, 1H,
NCHS), 8.68 (d, 1H, JHH = 8.4 Hz, Ar-H), 8.60 (d, 1H, JHH = 8 Hz, Ar-H), 8.02 (m, 1H, Ar-
H), 7.91 (m, 1H, Ar-H), 6.01 (s, 2H, CH2C6(CH3)5), 2.94, 2.22, 2.16 (s, 15H, CH2C6(CH3)5).
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13C NMR (100.6 MHz, DMSO, 25 C, ppm): δ = 163.2 (NCS), 141.4, 137.7, 134.8, 134.0,
132.7, 130.4, 129.6, 126.1, 125.4, 118.2 (Ar-C, CH2C6(CH3)5), 52.7 (CH2), 17.7, 17.4, 17.1
(CH2C6(CH3)5). Anal. Calc. for C19H22BrNS (M = 376.35): C, 60.64; H, 5.89; N, 3.72; Found:
C, 60.55; H, 5.80; N, 3.64.
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1f; Yield: 74 mg, 73%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ = 10.84 (s, 1H,
NCHS), 8.55 (d, 1H, JHH = 7.6 Hz, Ar-H), 8.25 (d, 1H, JHH = 8.4 Hz, Ar-H), 7.86 (m, 4H,
CH2C6H4(CF3), 7.78 (d, 1H, JHH = 7.6 Hz, Ar-H), 7.71 (d, 1H, JHH = 7.6 Hz, Ar-H), 6.27 (s,
13
0
2H, CH2C6H4(CF3)). C NMR (100.6 MHz, DMSO, 25 C, ppm): δ = 163.7 (NCS), 144.8
19
(CF3), 141.2, 140.0, 132.3, 131.4, 128.3, 127.8, 126.1, 124.6, 116.9 (Ar-C), 60.6 (CH2). F
NMR (400 MHz, DMSO): δ = -61.23 (CF3). Anal. Calc. for C15H11BrF3NS (M = 374.22): C,
48.14; H, 2.96; N, 3.74; Found: C, 48.10; H, 2.87; N, 3.68.
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1g; Yield: 2.02 g, 93%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ = 10.77 (s, 1H,
NCHS), 8.57 (d, 1H, JHH = 8.4 Hz, Ar-H), 8.26 (d, 1H, JHH = 8.4 Hz, Ar-H), 7.99 (m, 1H, Ar-
0
H), 7.89 (m, 1H, Ar-H), 6.36 (s, 2H, CH2C6(F)5). 13C NMR (100.6 MHz, DMSO, 25 C,
ppm): δ = 163.2 (NCS), 162.9, 146.4, 143.5, 136.5, 133.9, 131.4, 130.7, 130.3, 129.1, 107.2
(Ar-C, CH2C6(F)5), 65.7 (CH2C6(F)5). 19F NMR (400 MHz, DMSO): δ -140.75, -149.76, -
159.22 (Ar-F). Anal. Calc. for C14H7BrF5NSS (M = 396.17): C, 42.44; H, 1.78; N, 3.54;
Found: C, 42.37; H, 1.65; N, 3.51.
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1h; Yield: 1.61 g, 80%. 1H NMR (400 MHz, DMSO, 25 0C, ppm): δ = 10.71 (s, 1H,
NCHS), 8.47 (d, 1H, JHH = 8 Hz, Ar-H), 8.24 (d, 1H, JHH = 8 Hz, Ar-H), 7.87 ( m, 2H, Ar-H),
4.86 (m, 2H, N-CH2), 2.48 (m, 2H, butyl-CH2), 1.91 (m, 2H, butyl-CH2), 1.35 (m, 3H, CH3).
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13C NMR (100.6 MHz, DMSO, 25 C, ppm): δ = 165.2 (NCS), 140.8, 132.1, 130.2, 129.0,
126.1, 117.9 (Ar-C), 53.0 (N-CH2), 34.8, 31.3 (butyl-CH2), 19.7 (CH3). Anal. Calc. for
C11H14BrNS (M = 272.20): C, 48.54; H, 5.18; N, 5.15; Found: C, 48.59; H, 5.12; N, 5.13.
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1ı; Yield: 2.05 g, 85%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ = 10.74 (s, 1H,
NCHS), 8.56 (d, 1H, JHH = 8 Hz, Ar-H), 8.43 (d, 1H, JHH = 8 Hz, Ar-H), 7.92 ( m, 1H, Ar-H),
7.83 (m, 1H, Ar-H), 4.53 (m, 2H, N-CH2), 2.48 (m, 2H, octyl-CH2), 1.90 (m, 2H, octyl-CH2),
1.26 (m, 8H, octyl-CH2), 0.81 (m, 3H, CH3). 13C NMR (100.6 MHz, DMSO, 25 0C, ppm): δ =
162.9 (NCS), 145.8, 137.6, 131.1, 130.0, 128.2, 117.6 (Ar-C), 52.8 (N-CH2), 34.6, 31.6, 31.5,
29.2, 29.0, 27.6 (octyl-CH2), 22.4 (CH3). Anal. Calc. for C15H22BrNS (M = 327.31): C, 54.87;
H, 6.75; N, 4.27; Found: C, 54.79; H, 6.72; N, 4.19.
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1i; Yield: 2.29 g, 81%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ = 10.81 (s, 1H,
NCHS), 8.57 (d, 1H, JHH = 8 Hz, Ar-H), 8.43 (d, 1H, JHH = 8 Hz, Ar-H), 7.88 ( m, 1H, Ar-H),
7.80 ( m, 1H, Ar-H), 4.87 (m, 2H, N-CH2), 2.49 (m, 2H, dodecyl-CH2), 1.89 (m, 2H,
dodecyl-CH2), 1.14 (m, 16H, dodecyl-CH2), 0.77 (m, 3H, CH3). 13C NMR (100.6 MHz,
DMSO, 25 0C, ppm): δ = 164.9 (NCS), 140.6, 131.9, 1129.9, 128.7, 125.8, 117.6 (Ar-C), 52.8
(N-CH2), 34.5, 31.7, 29.4, 29.3, 29.1, 29.0, 28.9, 27.7, 27.0, 26.1 (dodecyl-CH2), 22.5 (CH3).
Anal. Calc. for C19H30BrNS (M = 383.13): C, 59.36; H, 7.87; N, 3.64; Found: C, 59.49; H,
7.82; N, 3.83.
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1j; Yield: 2.18 g, 63%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ = 10.65 (s, 1H,
NCHS), 8.53 (d, 1H, JHH = 8.4 Hz, Ar-H), 8.41 (d, 1H, JHH = 8.8 Hz, Ar-H), 7.88 (m, 2H, Ar-
13
H), 4.83 (m, 2H, N-CH2), 3.39 (m, 32H, octadecyl-CH2), 2.51 (m, 3H, octadecyl-CH3). C
NMR (100.6 MHz, DMSO, 25 0C, ppm): δ = 157.0 (NCS), 134.2, 132.3, 126.9, 126.2, 123.6,
123.2 (Ar-C), 51.9 (CH2), 40.8, 40.6, 40.4, 40.2, 40.0, 39.8, 32.0, 29.7, 26.3, 22.7, 17.0 (Al-
C), 14.6 (CH3). Anal. Calc. for C25H42BrNS (M = 468,58): C, 64.08; H, 9.03; N, 2.99; Found:
C, 64.15; H, 9.11; N, 2.91.
Benzothiazol-2-ylideneruthenium(II) Complexes (2a-j). Under argon atmosphere,
mixture of [RuCl2(p-cymene)]2 (100 mg; 0.16 mmol) in dicholoromethane (10 mL) was added
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ACCEPTED MANUSCRIPT
to benzothiazolium salts (1a-j) (0.32 mmol) with Ag2O (60 mg; 0.24 mmol) was stirred 24 h
o
at 25 C. Meanwhile the reaction progress was monitored with thin layer chromatography.
After filtration removal of the solvent under vacuo, the ruthenium compound was purified by
column chromatography on silica gel using CH2Cl2/EtOAc as the eluent (v/v = 30:90) to give
a reddish brown solid (2a). The residue was recrystallized from CH2Cl2/Et2O (v/v = 4:12 mL).
The following complexes (2b-j) were synthesized according to this procedure.
2a: Yield: 114 mg, 67%. 1H NMR (400 MHz, CDCl3, TMS, 25 0C, ppm): δ 7.78 (d,
1H, JHH = 7.4 Hz, Ar-H), 7.36 (m, 6 H, Ar-H, CH2C6H5), 7.09 (d, 1H, JHH = 7.4 Hz,
CH2C6H5), (6.36 (s, 2 H, CH2C6H5), 5.28, 5.14 (m, 4H, C10H14(C6H4)), 2.83 (m, 1H,
C10H14(CH(CH3)2)), 2.10 (s, 3H, C10H14(CH3)), 1.21 (d, 6H, JHH = 16 Hz, C10H14(CH(CH3)2)).
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13C NMR (100.6 MHz, CDCl3, TMS, 25 C, ppm): δ = 227.3 (NCS), 144.7, 136.4, 136.1,
129.4, 128.1, 126.5, 125.7, 125.0, 121.6, 111.9, 106.5, 100.9, 86.7, 86.3, (Ar-C), 57.0 (CH2),
30.8 (Ar-C), 22.4 (Ar-C), 18.6 (Ar-C). Anal. Calc. for C24H26Cl2NRuS (M = 532.51): C,
54.13; H, 4.92; N, 2.63; Found: C, 54.05; H, 4.86; N, 2.69.
2b:
Yield: 113 mg, 65%. 1H NMR (400 MHz, CDCl3, TMS, 25 0C, ppm): δ = 7.67 (d,
1H, JHH = 6.8 Hz, Ar-H), 7.24 (m, 3H, Ar-H), 7.09 (d, 2H, JHH = 8 Hz, CH2C6H4(CH3)), 6.88
(d, 2H, JHH = 8 Hz, CH2C6H4(CH3)), 6.22 (s, 2H, CH2C6H4(CH3)), 5.22 (d, 2H, JHH = 6 Hz,
C10H14(C6H4)), 5.08 (d, 2H, JHH = 5.6 Hz, C10H14(C6H4)), 2.74 (m, 1H, C10H14(CH(CH3)2)),
2.26 (s, 3H, CH2C6H4(CH3)), 2.00 (s, 3H, C10H14(CH3)), 1.15 (d, 6H, JHH = 6.9 Hz,
C10H14(CH(CH3)2)). 13C NMR (400 MHz, CDCl3): δ 227.4 (NCS), 144.8, 137.9, 136.3, 133.5,
130.2, 126.5, 125.5, 124.9, 115.0, 106.4, 101.0, 100.9, 86.7, 86.3 (Ar-C), 56.9 (CH2), 30.8,
22.5, 21.3, 18.4 (Ar-C). Anal. Calc. for C25H28Cl2NRuS (M = 546.54): C, 54.94; H, 5.16; N,
2.56; Found: C, 54.84; H, 5.21; N, 2.51.
2c:
Yield: 128 mg, 70%. 1H NMR (400 MHz, CDCl3, TMS, 25 0C, ppm): δ = 7.72 (d,
1H, JHH = 7.8 Hz, Ar-H), 7.28 (d, 1H, JHH = 7.8 Hz, Ar-H ), 7.19 (t, 1H, JHH = 7.8 Hz, Ar-
H), 7.08 (d, 1H, JHH = 7.8 Hz, Ar-H ), 6.82 (s, 2H, CH2C6H2(CH3)3), 6.35 (s, 2H,
CH2C6H2(CH3)3), 5.45 (d, 2H, JHH = 5.8 Hz, C10H14(C6H4)), 5.28 (d, 2H, JHH = 5.8 Hz,
C10H14(C6H4)), 2.94 (m, 1H, C10H14(CH(CH3)2)), 2.25 (s, 3H, CH2C6H2(CH3)3), 2.10 (s, 3H,
C10H14(CH3)), 2.04 (s, 6H, CH2C6H2(CH3)3, 1.25 (d, 6H, JHH = 6.9 Hz, C10H14(CH(CH3)2)).
13C NMR (400 MHz, CDCl3): δ 225.8 (NCS), 145.4, 137.6, 136.5, 133.4, 130.1, 126.4, 125.5,
124.9, 121.6, 115.0, 106.4, 100.9, 87.3, 87.0, (Ar-C), 55.8 (CH2), 30.9 (Ar-C), 22.5, 21.0,
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ACCEPTED MANUSCRIPT
20.5, 18.3 (Ar-C). Anal. Calc. for C27H32Cl2NRuS (M = 574.59): C, 56.44; H, 5.61; N, 2.44;
Found: C, 56.49; H, 5.68; N, 2.41.
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2d
:
Yield: 120 mg, 64%. 1H NMR (400 MHz, CDCl3, TMS, 25 C, ppm): δ = 7.71
(m, 1H, Ar-H), 7.26 (m, 1H, Ar-H), 7.10 (m, 1H, Ar-H), 7.00 (s, 2H, CH2C6H(CH3) 4), 6.44
(s, 1H, CH2C6H(CH3)4), 5.50 (d, 2H, JHH = 6.1 Hz, C10H14(C6H4)), 5.36 (d, 2H, JHH = 6.1 Hz,
C10H14(C6H4)) 2.94 (m, 1H, C10H14(CH(CH3)2)), 2.21 (s, 6H, CH2C6H(CH3)4), 2.16 (s, 6H,
CH2C6H(CH3)4), 2.03 (s, 3H, C10H14(CH3)), 1.25 (d, 6H, JHH = 6.9 Hz, C10H14(CH(CH3)2)).
13C NMR (400 MHz, CDCl3): δ 223.8 (NCS), 144.0, 135.6, 133.8, 131.7, 131.0, 129.9, 124.8,
123.4, 120.0, 113.3, 105.5, 98.5, 86.2, 85.7 (Ar-C), 55.9 (CH2), 37.7 (Ar-C), 29.6, 21.3, 19.6,
17.2, 14.7 (Ar-C). Anal. Calc. for C28H34Cl2NRuS (M = 588.62): C, 57.13; H, 5.82; N, 2.38;
Found: C, 57.19; H, 5.88; N, 2.35.
0
2e
:
Yield: 131 mg, 68%. 1H NMR (400 MHz, CDCl3, TMS, 25 C, ppm): δ = 7.70
(m, 1H, Ar-H), 7.23 (m, 1H, Ar-H), 7.06 (m, 1H, Ar-H), 6.84 (d, 2H, Ar-H), 6.44 (s, 2H,
CH2C6(CH3)5) 5.52 (d, 2H, JHH = 6.1 Hz, C10H14(C6H4)), 5.30 (d, 2H, JHH = 6.1 Hz,
C10H14(C6H4)), 2.97 (m, 1H, C10H14(CH(CH3)2)), 2.28 (s, 3H, CH2C6(CH3)5), 2.20 (s, 6H,
CH2C6(CH3)5), 2.18 (s, 3H, C10H14(CH3)), 2.11 (s, 6H, CH2C6(CH3)5), 1.29 (d, 6H, JHH = 6.9
13
Hz, C10H14(CH(CH3)2)). C NMR (400 MHz, CDCl3): δ 224.7 (NCS), 145.3, 136.9, 135.6,
133.8, 132.7, 125.9, 128.6, 124.4, 121.2, 114.7, 106.6, 99.9, 87.3, 86.8, (Ar-C), 57.7 (CH2),
30.9 (Ar-C), 22.5, 18.5, 17.5, 17.0, 15.4 (Ar-C). Anal. Calc. for C29H36Cl2NRuS (M =
602.64): C, 57.80; H, 6.02; N, 2.32; Found: C, 57.75; H, 6.11; N, 2.29.
2f:
Yield: 117 mg, 61%.1H NMR (400 MHz, CDCl3, TMS, 25 0C, ppm): δ = 7.79 (d,
1H, JHH = 8.1 Hz, Ar-H), 7.63 (d, 2H, JHH = 8.1 Hz, Ar-H), 7.28 (m, 5H, Ar-H,
CH2C6H4(CF3)), 6.43 (s, 2H, CH2C6H4(CF3)), 5.33 (d, 2H, JHH = 6.1 Hz, C10H14(C6H4)), 5.17
(d, 2H, JHH = 6.1 Hz, C10H14(C6H4)), 2.86 (m, 1H, C10H14(CH(CH3)2)), 2.15 (s, 3H,
C10H14(CH3)), 1.21 (d, 6H, JHH = 6.9 Hz, C10H14(CH(CH3)2)). 13C NMR (400 MHz, CDCl3):
δ 230.8 (NCS), 144.3, 140.6, 136.3, 126.7, 126.2, 125.3 125.1, 122.6, 121.8, 115.0, 107.1,
19
101.0, 86.8, 86.5 (Ar-C), 57.1 (CH2), 30.9 (Ar-C), 22.4, 18.4 (Ar-C). F NMR (400 MHz,
CDCl3): δ -63.05 (CF3). Anal. Calc. for C25H25Cl2F3NRuS (M = 600.51): C, 50.00; H, 4.20;
N, 2.33; Found: C, 50.09; H, 4.26; N, 2.38.
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ACCEPTED MANUSCRIPT
2g: Yield: 129 mg, 65%. 1H NMR (400 MHz, CDCl3, TMS, 25 0C, ppm): δ = 7.79 (d,
1H, JHH = 7.5 Hz, Ar-H), 7.36 (m, 2H, Ar-H), 7.16 (d, 1H, JHH = 7.5 Hz, Ar-H), 5.50 (d, 2H,
JHH = 6.1 Hz, C10H14(C6H4)), 5.35 (d, 2H, JHH = 6.1 Hz, C10H14(C6H4)), 2.97 (m, 1H,
C10H14(CH(CH3)2)), 2.18 (s, 3H, C10H14(CH3)), 1.30 (d, 6H, JHH
= 6.9 Hz,
C10H14(CH(CH3)2)). 13C NMR (400 MHz, CDCl3): δ 229.8 (NCS), 145.9, 143.8, 143.5, 139.4,
136.8, 136.3, 126.8, 125.3, 122.0, 112.9, 109.2, 100.1, 87.3, 87.2, (Ar-C), 49.6 (CH2), 31.2,
31.0, 30.8 (Ar-C), 22.5, 22.4, 19.0, 18.7, 18.4 (Ar-C). 19F NMR (400 MHz, CDCl3): δ 102.3,
102.9, 104.9, 110.4, 111.2, 120.8, 124.6, 125.2 (Ar-F). Anal. Calc. for C24H21Cl2F5NRuS (M
= 622.46): C, 46.31; H, 3.40; N, 2.25; Found: C, 46.37; H, 3.36; N, 2.18.
0
2h: Yield: 108 mg, 68%. 1H NMR (400 MHz, CDCl3, TMS, 25 C, ppm): δ = 7.74
(d, 1H, JHH = 7.6 Hz, Ar-H), 7.63 (d, 1H, JHH = 8.4 Hz, Ar-H), 7.48 (m, 1H, Ar-H), 7.33 (m,
1H, Ar-H), 5.42 (d, 2H, JHH = 6.1 Hz, C10H14(C6H4)), 5.30 (d, 2H, JHH = 6.1 Hz,
C10H14(C6H4)), 4.91 (m, 2H, N-CH2), 2.88 (m, 1H, C10H14(CH(CH3)2)), 2.18 (s, 3H,
C10H14(CH3)), 2.05 (m, 2H, butyl-CH2), 1.60 (m, 2H, butyl-CH2), 1.27 (d, 6H, JHH = 6.9 Hz,
13
C10H14(CH(CH3)2)), 1.21 (m, 3H, butyl-CH3). C NMR (400 MHz, CDCl3): δ 224.2 (NCS),
144.2, 136.8, 126.3, 124.8, 121.5, 114.3, 107.0, 100.9, 86.9, 86.6 (Ar-C), 65.9 (CH2), 54.6,
32.4, 30.8, 22.6, 20.6, 18.6, 14.1 (Al-C). Anal. Calc. for C21H28Cl2NRuS (M = 498.49): C,
50.60; H, 5.66; N, 2.81; Found: C, 50.53; H, 5.68; N, 2.74.
0
2ı; Yield: 112 mg, 63%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ = 7.73 (d, 1H,
JHH = 7.6 Hz, Ar-H), 7.60 (d, 1H, JHH = 7.6 Hz, Ar-H), 7.48 ( m, 1H, Ar-H), 7.35 ( m, 1H, Ar-
H), 5.46 (d, 2H, JHH = 6.1 Hz, C10H14(C6H4)), 5.29 (d, 2H, JHH = 6.1 Hz, C10H14(C6H4)),
4.88 (m, 2H, N-CH2), 2.87 (m, 1H, C10H14(CH(CH3)2)), 2.19 (m, 2H, octyl-CH2), 2.17 (s, 3H,
C10H14(CH3)), 1.53 (m, 2H, octyl-CH2), 1.27 (m, 8H, octyl-CH2), 1.23 (d, 6H, JHH = 6.9 Hz,
C10H14(CH(CH3)2)), 0.87 (m, 3H, octyl-CH3). 13C NMR (100.6 MHz, DMSO, 25 0C, ppm): δ
224.1 (NCS), 144.0, 136.7, 126.0, 124.5, 121.4, 114.0, 106.8, 100.6, 87.0, 86.4 (Ar-C), 54.5
(N-CH2), 31.7, 30.6, 30.2, 29.6, 29.2, 27.1, 22.6, 22.2, 18.3, 14.1 (Al-C). Anal. Calc. for
C25H35Cl2NRuS (M = 553.09): C, 54.24; H, 6.37; N, 2.53; Found: C, 54.29; H, 6.22; N, 2.63.
0
2i; Yield: 127 mg, 65%. 1H NMR (400 MHz, DMSO, 25 C, ppm): δ = 7.74 (d, 1H,
JHH = 8.0 Hz, Ar-H), 7.61 (d, 1H, JHH = 8.0 Hz, Ar-H), 7.48 ( m, 1H, Ar-H), 7.35 ( m, 1H, Ar-
H), 5.47 (d, 2H, JHH = 6.6 Hz, C10H14(C6H4)), 5.30 (d, 2H, JHH = 6.4 Hz, C10H14(C6H4)),
4.89 (m, 2H, N-CH2), 2.88 (m, 1H, C10H14(CH(CH3)2)), 2.18 (s, 3H, C10H14(CH3)), 2.01 (m,
16

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2H, dodecyl-CH2), 1.55 (m, 2H, dodecyl-CH2), 1.29 (m, 16H, dodecyl-CH2), 1.27 (d, 6H, JHH
13
= 6.9 Hz, C10H14(CH(CH3)2)), 0.88 (m, 3H, dodecyl-CH3). C NMR (100.6 MHz, DMSO,
25 0C, ppm): δ 224.2 (NCS), 144.0, 137.0, 125.9, 124.5, 121.4, 113.9, 106.8, 100.7, 86.6, 86.3
(Ar-C), 54.6 (N-CH2), 31.8, 30.6, 30.6, 30.2, 29.6, 29.5, 29.4, 29.3, 27.2, 27.1, 22.6, 22.2,
18.3, 14.1 (Al-C). Anal. Calc. for C29H43Cl2NRuS (M = 609.15): C, 57.13; H, 7.11; N, 2.30;
Found: C, 57.17; H, 7.12; N, 2.43.
2j: Yield: 142 mg, 64%. 1H NMR (400 MHz, CDCl3, TMS, 25 0C, ppm): δ = 7.72 (d,
1H, JHH = 7.6 Hz, Ar-H), 7.33 (d, 1H, JHH = 8 Hz, Ar-H), 7.46 (m, 1H, Ar-H), 7.35 (m, 1H,
Ar-H), 5.45 (d, 2H, JHH = 5.6 Hz, CH2), 5.29 (d, 2H, JHH = 5.6 Hz, CH2), 4.88 (m, 2H, N-
CH2), 2.87 (m, 1H, C10H14(CH(CH3)2)), 2.16 (s, 3H, C10H14(CH3)), 1.47 (m, 41H, Ar-H,
C10H14(CH(CH3)2). 13C NMR (400 MHz, CDCl3): δ 224.3 (NCS), 144.2, 137.0, 126.2, 124.7,
121.6, 114.2, 107.0, 100.9, 86.8, 86.6 (Ar-C), 54.8 (CH2), 32.2, 30.8, 30.5, 29.9, 29.8, 29.6,
27.4, 22.9, 22.6, 18.6, 14.3 (Al-C). Anal. Calc. for C35H56Cl2NRuS (M = 694.87): C, 60.50;
H, 8.12; N, 2.02; Found: C, 60.44; H, 8.21; N, 2.06.
Synthesis of tethered Ruthenium Carbene Complex (3e). The ruthenium(II)
complex (2e) (0.32 mmol) was dissolved in dry toluene under argon atmosphere which was
stirred 4 h at 110oC. After cooling a red solid was obtained which was washed with Et2O.
Yield: 108 mg, 72%. 1H NMR (400 MHz, DMSO): δ 8.04 (d, 1H, JHH = 7.6 Hz, Ar-H),
7.96 (d, 1H, JHH = 8 Hz, Ar-H), 7.65 (m, 1H, Ar-H), 7.49 (m, 1H, Ar-H), 5.65 (s, 2H, CH2),
1.89 (m, 15 H, Ar-CH3). Anal. Calc. for C19H22Cl2NRuS (M = 468.43): C, 48.72; H, 4.73;
N,2.99;Found:C,48.65;H,4.68;N,2.91.
.
General Procedure for the Transfer Hydrogenation Reactions. A mixture of
acetophenone (1,5 mmol), the catalyst (0.01 mmol) and propan-2-ol (18,5 mL) were stirred at
82 ºC for 10 minutes. 1,5 mL of 0.1 M KOH (0.15 mmol) solution in propan-2-ol was added.
The solution was stirred at the refluxing temperature. At the desired reaction times, aliquots
1
were withdrawn from reaction vessel. The reaction progress was monitored by GC and H-
NMR. The yields were recorded for an average of two runs.
Acknowledge
Financial support from Ege University (Project 2011-FEN-091) is gratefully
acknowledged.
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Supporting Information
CCDC 905470, 905471and 905473 contain the supplementary crystallographic data for 2d, 2e
and 2g. These data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.htmL (or from the CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk) and
NMR studies for 2e and 3e.
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[18] 2e was heated in boiling 2-PrOH. Precatalyst 2e was monitored by 1H NMR in different
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stability of the resulting complex (3e) is higher than p-cymene complex 2e due to the
chealating effect. Although the quality of the 1H NMR data collected was limited by the poor
solubility of 3e in DMSO at RT, structural information on the catalyst was obtained.
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Piano-Stool Benzothiazol-2-ylidene Ru(II) Complexes for Effective Transfer
Hydrogenation of Carbonyls
Zeynep İpek Oruç, Lütfiye Gök, Hayati Türkmen,* Onur Şahin, Orhan Büyükgüngör, Bekir
Çetinkaya
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R
a
b
c
d
e
f
IPA
KOH
2a-i
g
h
-(CH2)6CH3
-(CH2)10CH3
ı
i
j
2c < 2e < 2d ≈ 2a < 2b < 2f < 2h < 2ı< 2i < 2j <2g
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Figure 4. Time-dependent 1 H NMR spectra for complexes 3e and 4e
N
S
N
S
Ru
Cl
Ru
Cl
- (p-cymene)
Cl
Cl
2e
3e
3e
Major 3e
2e + 3e
Major 2e

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Research highlights for
Piano-Stool Benzothiazol-2-ylidene Ru(II) Complexes for Effective Transfer Hydrogenation
of Carbonyls
► A series benzothiazolium bromides with a variety of alkyl chain or benzyl substituents on
N atom were synthesized and metalated with ruthenium precursors.
► The catalytic properties of the complexes in transfer hydrogenation reaction of ketones
and aldehydes were investigated
► The observance of higher catalytic activity for benzyl substituents on N atom of ligand
influence catalytic tranfer hydrogenation and possibly indicates the existence of cooperative
effects during catalysis.
► Their catalytic properties may be interpreted that electronic influences and micele effects
of the ligand.