Ruthenium complexes bearing tridentate 2-(methylthio)phenylsalicylaldimine Schiff-base ligands

Article abstract of DOI:10.1016/j.ica.2017.06.004

Reaction of [Ru(PPh₃)₃Cl₂] with 2-(methylthio)phenylsalicylaldimine Schiff-base (HL) in tetrahydrofuran (THF) in the presence of triethylamine afforded a ruthenium(II) complex [Ru(ONS-L)(PPh₃)₂Cl]·CH₃OH·2.75H₂O (1). Similarly, reaction of [Ru(CO)₂Cl₂] with HL in N,N′-dimethylformamide (DMF) in the presence of triethylamine gave a ruthenium(II) complex [Ru(ONS-L)(CO)₂Cl] (2), while the reaction between [Ru(CO)₂Cl₂] and HL without base resulted in a ruthenium(III) complex [Ru(ONS-L)(CO)Cl₂] (3). Treatment of RuCl₃·3H₂O with HL in ethanol in the presence of triethylamine gave an anionic complex [Et₃NH][Ru(ONS-L)Cl₃] (4), which reacted with [Cp^?₂Ru] in the presence of sodium hydroxide to give complex [Cp^?Ru(η⁶-1,2,3,4-Me₄C₆H₂)][Ru(ONS-L)Cl₃]·CH₂Cl₂ (5) with a different cation. Besides, reaction of 4 and AgNO₃ afforded a dinuclear ruthenium(II) complex [Ru₂(ONS-L)(μ-ONS-L)₂Cl]·CH₂Cl₂ (6). The structures of complexes 1–6 have been established by X-ray crystallography, of which complex 4 was selected as a catalyst for the typical oxidation of 1-phenylethanol to the according acetophenone.

Full text of DOI:10.1016/j.ica.2017.06.004

Accepted Manuscript
Research paper
Ruthenium complexes bearing tridentate 2-(methylthio)phenylsalicylaldimine
Schiff-base ligands
Chang-Jiu Wang, Hui Lin, Xin Chen, Ai-Quan Jia, Qian-Feng Zhang
PII:
S0020-1693(16)30829-5
http://dx.doi.org/10.1016/j.ica.2017.06.004
ICA 17652
DOI:
Reference:
To appear in:
Inorganica Chimica Acta
Received Date:
Revised Date:
Accepted Date:
8 November 2016
9 May 2017
2 June 2017
Please cite this article as: C-J. Wang, H. Lin, X. Chen, A-Q. Jia, Q-F. Zhang, Ruthenium complexes bearing tridentate
2
-(methylthio)phenylsalicylaldimine Schiff-base ligands, Inorganica Chimica Acta (2017), doi: http://dx.doi.org/
1
0.1016/j.ica.2017.06.004
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Ruthenium complexes bearing tridentate
2-(methylthio)phenylsalicylaldimine Schiff-base ligands
Chang-Jiu Wang, Hui Lin, Xin Chen, Ai-Quan Jia, and Qian-Feng Zhang*
Institute of Molecular Engineering and Applied Chemistry, and
Anhui Province Key Laboratory of Metallurgy Engineering & Resources Recycling,
Anhui University of Technology, Ma’anshan, Anhui 243002, P. R. China
Abstract: Reaction of [Ru(PPh
in tetrahydrofuran (THF) in the presence of triethylamine afforded a ruthenium(II) complex
Ru(ONS-L)(PPh Cl]⋅CH OH⋅2.75H O (1). Similarly, reaction of [Ru(CO) Cl ] with HL in
N,N’-dimethylformamide (DMF) in the presence of triethylamine gave a ruthenium(II) complex
Ru(ONS-L)(CO) Cl] (2), while the reaction between [Ru(CO) Cl ] and HL without base resulted
in a ruthenium(III) complex [Ru(ONS-L)(CO)Cl ] (3). Treatment of RuCl ⋅3H O with HL in
NH][Ru(ONS-L)Cl ] (4),
3 3 2
) Cl ] with 2-(methylthio)phenylsalicylaldimine Schiff-base (HL)
[
3
)
2
3
2
2
2
[
2
2
2
2
3
2
ethanol in the presence of triethylamine gave an anionic complex [Et
3
3
*
which reacted with [Cp
2
Ru] in the presence of sodium hydroxide to give complex
)][Ru(ONS-L)Cl ]⋅CH Cl (5) with a different cation. Besides,
AgNO afforded dinuclear ruthenium(II) complex
Cl]⋅CH Cl (6). The structures of complexes 1‒6 have been established
6
[
Cp*Ru(η -1,2,3,4- Me
4
C
6
H
2
3
2
2
reaction
of
4
and
3
a
[
Ru (ONS-L)(µ-ONS-L)
2
2
2
2
by X-ray crystallography, of which complex 4 was selected as a catalyst for the typical oxidation
of 1-phenylethanol to the according acetophenone.
Keywords: ruthenium(II), ruthenium(III), Schiff base ligand, catalytic oxidation, X-ray structure
_
*
__________________
Corresponding author. Tel. & fax.: +86-555-2311059.
E-mail address: zhangqf@ahut.edu.cn (Q. F. Zhang).
1

1. Introduction
Schiff-base ligands offer a considerable versatility in their substituent groups, and thus the
possibility exists for designing transition metal complexes with useful biological and catalytic
properties [1,2]. Transition metal complexes of Schiff-base ligands have witnessed prodigious
growth since they were firstly isolated in the middle nineteenth century principally through their use
in
a
variety of catalytic applications [3]. The popular Schiff-base ligand salen
donor that readily coordinate to
[
N,N’-bis(salicylidene)ethylenediamine] is a tetradentate N O
2 2
transition metals [4]. Extension of the study to include bidentate NO and tridentate ONP or ONS
donor sets is capable of providing multi-choice coordination types, and it has been accordingly
understood that a few polynuclear complexes bearing Schiff-base ligands are abundant in the
literature, owing to the case that they can be modified by various functional groups [5,6]. As is well
known, organic molecules possessing O, N and S donor sites are important in the development of
coordination chemistry as well as in the biomimetic chemistry of a number of transition metals [7].
For examples, titanium complexes with the Schiff-base ONS ligands are good catalyst precursors
for olefin polymerization [8]. To further understand the side-arm effects of the extra donor and the
structure-reactivity relationship of the catalysts, we have become interested in developing the
ruthenium complexes with the monoanionic tridentate Schiff-base ONS-donor ligand
2
2
-(methylthiophenyl)salicylaldimine. Only a few transition metal complexes with the ligand
-(methylthiophenyl)salicylaldimine were reported, including copper, nickel, zinc and vanadium
[
9,10]. Recently, some arene-ruthenium and ruthenium-carbonyl complexes with sulfur-containing
tri-dendate Schiff base ligands derived from o-aminothiophenol, 2-(methylthio)aniline or
-(alkylthio)benzaldehyde have been synthesized for the catalysis oxidation of alcohols to carbonyl
2
compounds [11]. Previously, we have reported a series of ruthenium complexes with bidentate
Schiff-base ligands and their catalytic behavior towards alcohols [12]. As our long-standing
research interest in the ruthenium-sulfur complexes, we disclose herein syntheses, structures,
reactions and catalytic oxidation properties of ruthenium(II)/ruthenium(III) complexes bearing
tridentate 2-(methylthio)phenylsalicylaldimine (ONS-L) Schiff-base ligands in this paper.
2. Experimental section
2

2.1. General considerations
All synthetic manipulations were carried out under dry nitrogen by standard Schlenk
techniques. Solvents were purified by standard procedures and distilled prior to use. Schiff-base
ligand 2-(methylthiophenyl)salicylaldimine (ONS-LH) was prepared by the condensation between
salicyaldehyde and o-amino-(methylthiophenol) in ethanol. Commercially available RuCl
3
2
⋅3H O
(
[
Shanxi Chemical Company) was used without further purification. The starting complexes
*
Ru(PPh
3
)
Cl
3 2
] [13], [Ru(CO)
2
Cl
2
] [14], and [Cp Ru] [15], were prepared as reported previously.
2
NMR spectra were recorded on a Bruker ALX 400 Plus spectrometer operating at 400 and 162 MHz
1
31
1
for H and P, respectively. Chemical shifts (δ, ppm) were reported with reference to SiMe
4
( H)
3
1
and H PO ( P). Infrared spectra (KBr) were recorded on a Perkin-Elmer 16 PC FT-IR
3 4
spectrophotometer with use of pressed KBr pellets and positive FAB mass spectra were recorded on
a Finnigan TSQ 7000 spectrometer. Elemental analyses were carried out using a Perkin-Elmer 2400
CHN analyzer.
2
.2. Synthesis of [Ru(ONS-L)(PPh
3
)
2
Cl]⋅0.5CH
To a solution of ONS-LH (486 mg, 2.0 mmol) in THF (20 mL) was added [Ru(PPh
mg, 2.0 mmol), which was then stirred under N for 15 min. Triethylamine (Et N) (202 mg, 2.0
3
OH⋅2.75H
2
O (1)
3 3 2
) Cl ] (868
2
3
mmol) was introduced, and the reaction mixture was stirred overnight at room temperature, during
which the color of solution changed from brown to dark red brown. After removal of solvents in
vacuo, CH
the residue was washed with Et
Recrystallization from MeOH/ Et
suitable for X-ray diffraction in five days. Yield: 1.19 g, 63% (based on Ru). IR (KBr disc, cm ):
2
Cl
2
(20 mL) was added and the solution was filtered. The filtrate was concentrated and
O (5 mL × 2) and hexane (5 mL × 2) to give the desired product.
2
O (1: 3) afforded dark red block crystals of 1⋅0.5CH OH⋅2.75H O
2
2
3
−1
3
1
1
3
3
597 (νC=N), 1311 (νC−O), 739 (νC−S), 1432, 1087 and 691 (νPPh ); P NMR (CDCl , 162 MHz): δ
1
1
6.4 (s, PPh
3
), 14.7 (s, PPh
3
) ppm. H NMR (CDCl
3
, 400 MHz): δ 8.81 (s, 1H, CH=N), 7.98−7.31
(
(
m, 4H, Ar-H), 7.23−7.06 (m, 4H, Ar-H), 6.75−7.01 (m, 30H, PPh
3
), 2.39 (s, 3H, SCH
3
) ppm. MS
+
+
+
+
+
FAB): m/z 903 [M ], 868 [M − Cl], 641 [M − PPh
3
], 379 [M − 2PPh
3
], 344 [Ru(ONS-L)] . Anal.
Calc. for C50
H42NOP
2
ClSRu⋅0.5(CH
4
O)⋅2.75(H
2
O) (%): C, 64.74; H, 4.98; N, 1.48. Found: C, 64.67; H,
5.03; N, 1.43.
2
2.3. Synthesis of [Ru(ONS-L)(CO) Cl] (2)
3

To a slurry of [Ru(CO)
ONS-LH (486 mg, 2.0 mmol) and Et
was heated at 90 °C with stirring overnight, during which there was a color change from yellow to
orange. Addition of 30 mL Et O to the reaction solution gave orange-red precipitate which was
filtered and washed with Et O and hexane. The orange-red precipitate was dissolved in CH Cl (10
mL). The clearly orange filtrate was layered with Et O (20 mL) at room temperature, and orange
block-shaped crystals of 2 was harvested in three days. Yield: 704 mg, 81% (based on Ru). IR (KBr
2
Cl
2
] (456 mg, 2.0 mmol) in DMF (8 mL) was added a solution of
3
N (202 mg, 2.0 mmol) in EtOH (5 mL), and then the mixture
2
2
2
2
2
−1
1
disc, cm ): 1980 and 1963 (νC≡O), 1592 (νC=N), 1327 (νC−O), 745 (νC−S). H NMR (400 MHz,
CDCl ): δ 8.83 (s, 1H, CH=N), 7.35−7.18 (s, 4H, Ar-H), 7.13−7.04 (s, 4H, Ar-H), 2.55 (s, 3H,
SCH
3
+
+
+
+
3
) ppm. MS (FAB): m/z 435 [M ], 407 [M − CO], 399 [M − Cl − 1], 379 [M − 2CO], 344
+
[
Ru(ONS-L)] . Anal. Calc. for C16
H12NO
3
ClSRu (%): C, 44.19; H, 2.78; N, 3.22%. Found: C, 44.12;
H, 2.81; N, 3.24%.
2
2.4. Synthesis of [Ru(ONS-L)(CO)Cl ] (3)
A mixture of [Ru(CO)
10 mL) was heated at reflux overnight. The solvent was removed in vacuo and the residue was
extracted with CH Cl . The extract was exposed to the atmosphere and stirred for an additional 2 h
2 2
Cl ] (456 mg, 2.0 mmol) and ONS-LH (486 mg, 2.0 mmol) in DMF
(
2
2
at room temperature, generating a green-brown solution. This solution was filtered where after the
microcrystalline solid formed was collected via filtration from the filtrate and dried in vacuo. Single
crystals suitable for X-ray diffraction were grown by slow evaporation of a 1:1 CH
2
Cl
2
/Et
2
O solvent
−1
mixture. Yield: 654 mg, 74% (based on Ru). IR (KBr disc, cm ): 1987 (νC≡O), 1594 (νC=N), 1332
+
+
+
(
[
ν
C−O), 748 (νC−S). MS (FAB): m/z 442 [M ], 414 [M − CO], 379 [Ru(ONS-L)Cl] , 344
+
Ru(ONS-L)] . Anal. Calc. for C15
H12NO
2
Cl
2
SRu (%): C, 40.73; H, 2.73; N, 3.17%. Found: C,
40.56; H, 2.76; N, 3.21%.
3 3
2.5. Synthesis of [Et NH][Ru(ONS-L)Cl ] (4)
To a slurry of ONS-LH (486 mg, 2.0 mmol) and Et
added a solution of RuCl ⋅3H O (523 mg, 2.0 mmol) in EtOH (15 mL). The mixture was stirred for
h at reflux, during which there was a color change from brown to dark green-brown. The solvent
was removed in vacuo and the residue was washed with Et O and further recrystallized from
MeCN/Et O at room temperature. Green-brown block crystals of 4 suitable for X-ray diffraction
3
N (ca. 0.1 mL) in EtOH (5 mL) was
3
2
2
2
2
4

−1
were obtained in three days. Yield: 740 mg, 67% (based on Ru). IR (KBr disc, cm ): 3431 (vN−H),
+
+
1
3 3
590 (νC=N), 1337 (νC−O), 752 (νC−S). MS (FAB): m/z 449 [Ru(ONS-L)Cl ] , 414 [Ru(ONS-L)Cl ] ,
+
+
3
79 [Ru(ONS-L)Cl] , 344 [Ru(ONS-L)] . Anal. Calc. for C20
H
28
N
2
OCl
3
SRu (%): C, 43.52; H, 5.11;
N, 5.08%. Found: C, 43.36; H, 5.16; N, 5.05%.
6
2
.6. Synthesis of [Cp*Ru(η -1,2,3,4-Me
4
C
6
H
2
)][Ru(ONS-L)Cl
3
]⋅CH
2
Cl
2
(5)
To a solution of 4 (110 mg, 0.2 mmol) and NaOH (8.0 mg，0.2 mmol）in EtOH (10 mL) was
*
2
added a solution of [Cp
Ru] (74 mg，0.2 mmol) in THF (5 mL). The mixture was stirred at reflux
overnight and the green-brown solution with a little precipitate was formed. The precipitate was
removed by filtration and the solvents were removed in vacuo. The residue was extracted with
CH
layered with Et
IR (KBr disc, cm ): 1594 (νC=N), 1342 (νC−O), 761 (νC−S). MS (FAB): m/z 449 [Ru(ONS-L)Cl
2
Cl
2
(10 mL) and green black crystals of 5⋅CH
2 2
Cl were obtained after allowing the filtrate
2
O (15 mL) at room temperature for five days. Yield: 140 mg, 78% (based on Ru).
−1
+
3
] ,
)] , 344
2
(%): C, 46.44; H, 4.79; N, 1.55%. Found:
+
+
6
+
4
14 [Ru(ONS-L)Cl
2
] , 379 [Ru(ONS-L)Cl] , 370 [Cp*Ru(η -1,2,3,4-Me
Ru(ONS-L)] . Anal. Calc. for C34 SRu ⋅CH Cl
C, 46.37; H, 4.74; N, 1.61%.
4
C
6
H
2
+
[
H
41NOCl
3
2
2
2
.7. Synthesis of [Ru
2
(ONS-L)(µ-ONS-L)
To a solution of 4 (110 mg, 0.2 mmol) in MeOH (5 mL) was dropwise added an aqueous
solution (2 mL) of AgNO (34 mg, 0.2 mmol) at 5 °C. The mixture was stirred for 1 h and the red
2
Cl]⋅CH
2 2
Cl (6)
3
brown solution with white precipitate was formed. The precipitate was removed by filtration and
the solution was refluxed for 6 h. The solvent was removed in vacuo and the residue was washed
with Et
crystals of 6⋅CH
based on Ru). IR (KBr disc, cm ): 1596 (νC=N), 1341 (νC−O), 758 (νC−S). H NMR (400 MHz,
CDCl ): δ 8.85 (s, 1H, CH=N), 8.77 (s, 1H, CH=N), 8.73 (s, 1H, CH=N), 7.39−7.13 (s, 12H, Ar-H),
.16−7.01 (s, 12H, Ar-H), 2.42 (s, 3H, SCH ), 2.35 (s, 3H, SCH ) ppm. MS
2 2 2 2
O and further recrystallized from CH Cl /Et O at room temperature. Red brown block
2
2
Cl suitable for X-ray diffraction were obtained in five days. Yield: 54 mg, 52%
−1
1
(
3
7
3
), 2.38 (s, 3H, SCH
3
3
+
+
+
+
(
FAB): m/z 964 [M ], 929 [M − Cl], 686 [Ru
2
(ONS-L)
2
] , 344 [Ru(ONS-L)] . Anal. Calc. for
C
42
H
36
N
3
O
3
ClS Ru ⋅CH Cl
3
2
2
2
(%): C, 49.21; H, 3.65; N, 4.00%. Found: C, 49.34; H, 3.58; N, 4.06%.
2.8. X-ray crystallography
5

A summary of crystallographic data and experimental details for [Ru(ONS-L)(PPh
3
)
2
Cl]⋅-
NH]-
(ONS-L)-
0
.5CH
Ru(ONS-L)Cl
µ-ONS-L) Cl]⋅CH
3
OH⋅2.75H
2
O
(1), [Ru(CO)
2
(ONS-L)Cl] (2), [Ru(CO)(ONS-L)Cl
2
]
(3), [Et
3
6
[
(
3
] (4), [Cp*Ru(η -1,2,3,4-Me
4
C
6
H
2
)][Ru(ONS-L)Cl ]⋅CH Cl (5), and [Ru
3
2
2
2
2
2
Cl
2
(6) are summarized in Table 1. Intensity data were collected on a Bruker
SMART APEX 2000 CCD diffractometer using graphite-monochromated Mo-Kα radiation (λ =
.71073 Å) at 296(2) K. The collected frames were processed with the software SAINT [16]. The
0
data was corrected for absorption using the program SADABS [17]. Structures were solved by the
2
direct methods and refined by full-matrix least-squares on F using the SHELXTL software package
[
18,19]. All non-hydrogen atoms were refined anisotropically. The positions of all hydrogen atoms
were generated geometrically (Csp3−H = 0.96 and Csp2−H = 0.93 Å) and included in the structure
factor calculations with assigned isotropic thermal parameters but were not refined. The methanol
and water molecules in 1 were isotropically refined without hydrogen atoms due to disorder, which
probably resulted in a relatively high R value in the final refinement. The largest peaks in the final
difference maps had heights of 1.688 (for 5) and 2.091 e Å−3 (for 6) are in the vicinity of the
ruthenium atoms. The Flack parameter value of −0.07(1) indicate that the correct enantiomorphs has
been selected in the structure of complex 4.
2.9. Procedure for catalytic oxidation of 1-phenylethanol
Oxidation of 1-phenylethanol to according acetophenone with NMO were catalyzed by the
presence of [Et
3
NH][Ru(ONS-L)Cl
3
] (4). A typical reaction using the complex 4 as catalyst is as
Cl was added to the mixture of
follows. A solution of complex 4 (1 mol%) in 10 mL of CH
2
2
substrate (1 mmol) and NMO (2 mmol). The mixture was stirred at room temperature for 12 h and
the solvent was evaporated under reduced pressure with a rotary evaporator resulting in a solid mass.
It was shaken with petroleum ether (30~40 °C) (20 mL). The oxidized product extracted into
petroleum ether was analyzed by GC.
3. Results and discussion
3.1. Synthesis of complexes 1−6
The synthetic route of ruthenium(II) and ruthenium(III) complexes 1−6 with monoanionic
tridentate [ONS-L] ligand is summarized in Scheme 1. Interaction of [Ru(PPh
3
)
3
Cl
2
] with
6

equivalent Schiff base ligand HL at room temperature in THF in the presence of organic base
afforded [Ru(ONS-L)(PPh Cl] (1). Similar reaction using [Ru(CO) Cl ] as the ruthenium starting
material gave a ruthenium(II) complex [Ru(ONS-L)(CO) Cl] (2). One PPh /CO and one chloro
ligands in [Ru(PPh Cl ]/[Ru(CO) Cl ] were just replaced by one tridentate O,N,S-ligand in the
present reaction system. While the reaction of [Ru(CO) Cl ] and HL in refluxing DMF without base
3
)
2
2
2
2
3
3
)
3
2
2
2
2
2
resulted in a ruthenium(III) complex [Ru(ONS-L)(CO)Cl
2
] (3). Treatment of RuCl
3
⋅3H
2
O with HL
] (4),
in ethanol in the presence of triethylamine gave an anionic complex [Et
3
NH][Ru(ONS-L)Cl
3
*
2
which reacted with [Cp
Ru] in the presence of sodium hydroxide to give complex
6
[
Cp*Ru(η -1,2,3,4-Me
4
C
6
H
2
)][Ru(ONS-L)Cl
3
] (5) with a different cation. Rearrangement of one
6
Cp* moiety was observed in the cation [Cp*Ru(η -1,2,3,4-Me
4
C
6
H
2
)], which was not reported
6
previously to our best knowledge, though [RuCl
material [20]. Besides, reaction of 4 and AgNO
ruthenium(II) complex [Ru (ONS-L)(µ-ONS-L)
2
(η -1,2,3,4-Me
4
C
6
H
2
)] was a versatile ruthenium
2
3
in methanol-aqueous solution afforded a dinuclear
2
2
Cl] (6). The ruthenium atoms in 6 are both six
coordinate, one ruthenium is coordinated by two O,N,S-ligands, the other one is coordinated by one
O,N,S-ligand, one chloro ligand and two sulfur atoms from bridging O,N,S-ligands.
3.2. Spectroscopic study of complexes 1−6
IR spectra of complexes 1−6 all showed the CH=N groups of Schiff base ligands at around
−1
1
595 cm , which are in good agreement with other ruthenium complexes with ONS Schiff base
ligands [9]. In ruthenium carbonyl complexes [Ru(ONS-L)(CO)
2
Cl] (2) and [Ru(ONS-L)(CO)Cl
2
]
−1
(
3), the stretching vibration modes of terminal C≡O groups were found at 1980 and 1963 cm for 2,
−1
and 1987 cm for 3, which are comparable to ruthenium carbonyl complexes with ONS Schiff base
derived from salicylaldehyde/4-substituted salicylaldehyde/2-hydroxy-1-naphthaldehyde and
(
−1
31
o-aminothiophenol) and triphenylphosphine ligands (1919−1933 cm ) [11]. Two P signals were
3
1
observed in the P NMR spectra of complex 1 (16.4 and 14.7 ppm) due to cis positions of the two
PPh ligands. The aldimine proton (–CH=N–) resonances of ruthenium(II) complexes 1 (δ = 8.81
3
ppm), 2 (δ = 8.83 ppm), and 6 (δ = 8.85, 8.77, 8.73 ppm) compared well to other transition metal
complexes containing ONS Schiff base ligands, e.g. [N-(3,5-di-tert-butylsalicylidene)-2-phenyl-
sulfanylanilinato]Ti(IV)Cl
3
[21]. The positive ion FAB mass spectra of 1−3 display the expected
+
+
+
+
peaks corresponding to the molecular ions {[M ], [M − Cl], [M − PPh
3
] or [M − CO], and
7

+
[
Ru(ONS-L)] with the characteristic isotopic distribution patterns.
3.3. Crystal structures of complexes 1−6
The structures of complexes 1‒6 have been established by X-ray crystallography. The
perspective views of the molecular structures of 1−6 are shown in Figs. 1−6, respectively. The
central ruthenium atom in 1 is bonded in a slightly distorted octahedral geometry, to six atoms: a
nitrogen atom, a sulfur atom and an oxygen atom of the Schiff base ligand, two phosphorus atoms
of triphenylphosphine ligands, and a terminal chloride atom. The Schiff base ligand acts in a
tridentate fashion with the bite O−Ru−S angle of 174.90(11)°, similar to those in a ruthenium
complexes with dianionic ONS Schiff base ligands (172.74(5)° and 173.80(5)°) [9], while in
III
sulfur-bridged dinuclear ruthenium complex [Ru
2
(L)
2
Cl
2
(NCCH
3
)
2
] (L = 2-((E)-(2-mercapto-
phenylimino)-methyl)-4,6-di-tert-butylphenolato), the O−Ru−S bite angle of 169.26° is smaller than
that in 1 [22]. The average Ru−P bond length is 2.3398(15) Å and the P−Ru−P bond angle with two
cis-binding PPh
3
ligands are 98.59(6)º in 1. The O−Ru−S bite angles are 173.15(7)º, 174.10(17)º,
175.98(18)º, 176.9(3)(5)º in 2, 3, 4 and 5, respectively, similar to that in mononuclear ruthenium
complex 1. In dinuclear ruthenium complex 6, there are two coordination modes of ONS Schiff base
ligand: bridging mode and teminal mode. The O−Ru−S bite angles of 173.06(19)º and 172.2(2)º in
the bridging Schiff base ligands are a little acuter than that in terminal one O(1)−Ru(1)−S(1)
(
176.9(3)º), possibly due to steric effect. However, the bridging O−Ru−S bite angles in 6 are still
III
larger than that in related complex [Ru
2
(L)
2
Cl
2
(NCCH
3
2
) ] (169.26°), possibly due to the dianionic
2
−
III
property of LONS in [Ru
2
(L)
2
Cl
2
(NCCH
3
)
2
] [22]. In addition, the distance between the two
III
ruthenium atoms in 6 is about 3.533 Å, much longer than that in [Ru
2
(L)
2
Cl
2
(NCCH
3
2
) ] (2.8091(2)
Å), indicating no metal−metal bonding [22]. The Ru−C bond lengths (1.871(3) and 1.907(4) Å) in 2,
and 1.823(11) Å in 3 and the Ru−C−O bond angles (178.9(3)°, 177.3(3)° in 2 and 177.9(10)° in 3)
are normal for the related ruthenium-carbonyl complexes [11,12]. The average Ru−Cl lengths are
2.314(5) Å, 2.371(2) Å and 2.379(4) Å for 3, 4 and 5, respectively, which are a little shorter than in
those in 1 (2.4659(16) Å) and 2 (2.4374(9) Å).
3.4. Catalytic test of complex 4 for oxidation of 1-phenylethanol
In order to explore the catalytic activity of the ruthenium(II)/(III) complexes with monoanionic
tridentate [ONS-L] ligands, complex 4 was selected as a catalyst, since it is a Ru(III) speccie and
has three labile chloro ligands. Oxidation of 1-phenylethanol in the presence of NMO as oxidant
8

and dichloromethane as solvent at room temperature was initially investigated. In the presence of
NMO alone, there was no detectable oxidation product of 1-phenylethanol [11,23]. Thus, the
catalytic oxidation of 1-phenylethanol was carried out using NMO, hydrogen peroxide or
tert-butyhydroperoxide as oxidant in order to select the suitable oxidant for the present catalyst.
With NMO, the yield of acetophenone was ca. 96%; 0.01 mmol of catalyst and 2 mmol of NMO
were sufficient for oxidation. The new ruthenium(III) complex with monoanionic ONS-Schiff base
ligand show higher catalytic activity compared to other simialr ruthenium(II) complexes with
dianionic ONS-Schiff base ligand [11]. Recently, the catalytic oxidation of alcohols by
Ru(II)/Ru(III) complexes containing Schiff-base and triphenylphosphine ligands have been reported
[
24,25]. Compared to these systems, the present catalytic system of complex 4 as a typical
ruthenium(III)-ONS-L catalyst is better in terms of the yield of acetophenone and mild reaction
conditions.
4. Conclusion
Six new ruthenium(II) and ruthenium(III) complexes with monoanionic tridentate Schiff base
ligands have been synthesized and characterized by microanalytical and spectroscopic methods.
Their molecular structures have been further determined by single-crystal X-ray crystallography.
Complex 4 as a typical ruthenium(III) catalyst with tridentate [ONS-L] ligand exhibited relatively
excellent catalytic performance on oxidation of 1-phenylethanol to corresponding acetophenone in
the presence of NMO. It may supply a simple and alternative method for the oxidation of different
kinds of alcohols under the mild conditions.
4. Supplementary material
Crystallographic data for [Ru(ONS-L)(PPh
3
)
2
Cl]⋅ 0.5CH
3
OH⋅2.75H
2
O (1), [Ru(CO)
2
(ONS-L)-
6
Cl] (2), [Ru(CO)(ONS-L)Cl
Ru(ONS-L)Cl ]⋅CH Cl (5), and [Ru
the Cambridge Crystallographic Data Centre as supplementary publication nos. CCDC
515392-1515397, respectively. Copies of the data can be obtained free of charge on application to
2
] (3), [Et
3
NH][Ru(ONS-L)Cl
3
] (4), [Cp*Ru(η -1,2,3,4-Me
4
C
6
H
2
)]-
[
3
2
2
2
(ONS-L)(µ-ONS-L)
2
Cl]⋅CH
2
Cl (6) have been deposited with
2
1
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: (+44)1233-336-033; e-mail:
9

deposit@ccdc.cam.ac.uk].
Acknowledgements
This project was supported the Natural Science Foundation of China (grant no. 21372007).
References
[
[
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16] SMART and SAINT+ for Windows NT Version 6.02a, Bruker Analytical X-ray Instruments Inc., Madison,
Wisconsin, USA (1998).
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[
[
[
17] G.M. Sheldrick. SADABS, University of Göttingen, Germany (1996).
18] G.M. Sheldrick. SHELXTL Software Reference Manual. Version 5.1, Bruker AXS Inc., Madison, Wisconsin,
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[
19] G.M. Sheldrick, Acta Crystallogr. A 64 (2008) 112.
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[
25] N. Gunasekaran, N. Remya, S. Radhakrishnan, and R. Karvembu, J. Coord. Chem. 64 (2011) 491.
10

Table 1. Crystallographic data and experimental details for [Ru(ONS-L)(PPh
3
)
2
Cl]⋅CH
3
OH⋅2.75H
2
O (1), [Ru(CO)
2
(ONS-L)Cl] (2),
6
[
Ru(CO)(ONS-L)Cl
2
] (3), [Et
3
NH][Ru(ONS-L)Cl
3
] (4), [Cp*Ru(η -1,2,3,4-Me
4
C
6
H
2
)][Ru(ONS-L)Cl
3
]⋅CH Cl (5),
2
2
and [Ru
2
(ONS-L)(µ-ONS-L) Cl]⋅CH
2
2
Cl (6).
2
complex
1⋅CH OH⋅2.75H O
2
3
4
5⋅CH Cl2
6⋅CH Cl2
3
2
2
2
empirical formula
formula weight
crystal system
a (Å)
C
50.5
H
2
46.63NO2.88P ClSRu
C
16
H
12NO
3
ClSRu
C
15
H
12NO
2
Cl
2
SRu
C
20
H
28
N
2
OCl
3
SRu
C
35
H
43NOCl
5
SRu
2
43 38 3 3 3 3 2
C H N O Cl S Ru
944.03
434.85
442.29
551.92
905.15
1049.43
monoclinic
13.1607(19)
12.2857(18)
30.171(5)
98.590(2)
monoclinic
9.807(2)
monoclinic
9.125(3)
orthorhombic
9.910(5)
monoclinic
9.374(8)
14.643(12)
27.81(2)
97.008(10)
3788(5)
monoclinic
16.969(4)
12.946(3)
20.929(4)
97.014(5)
4563.2(17)
b (Å)
14.291(3)
12.388(3)
110.853(2)
1622.5(6)
14.181(4)
16.229(4)
90.781(1)
2099.9(10)
14.348(7)
17.313(8)
c (Å)
β (°)
3
4823.6(12)
2462(2)
V (Å )
space group
P2
1
/c
P2
1
/n
P2
1
/n
P2
1
2
1
2
1
P2
1
/c
1
P2 /n
Z
4
4
4
4
4
4
-
3
D
calc (g cm )
1.300
296(2)
1947
1.780
296(2)
874
1.399
296(2)
876
1.489
1.587
296(2)
1828
1.528
296(2)
2112
temperature (K)
296(2)
1124
F(000)
-
1
µ(Mo-Kα) (mm )
0.530
29122
10893
1.272
9505
3646
1.103
10975
4074
1.060
14519
5589
1.234
19724
8300
1.015
28376
10377
total refln
independent refln
11

R
int
0.0492
559
0.0385
0.0755
0.0873
0.0555
0.1199
parameter
209
200
227
416
517
a
b
R1 , wR2 (I > 2σ(I)) 0.0526, 0.1347
0.0325, 0.0601
0.0589, 0.0678
0.965
0.0646, 0.1390
0.1084, 0.1645
0.839
0.0568, 0.1341
0.1282, 0.1648
1.010
0.1144, 0.2505
0.1622, 0.3075
1.088
0.0772, 0.0927
0.1070, 0.1524
0.993
a
b
R1 , wR2 (all data)
0.0900, 0.1563
c
GoF
0.979
Flack paramter
−
−
−
−0.07(1)
−
−
a
R1 = ΣF
wR2 = [Σw(F
GoF = [Σw(F
o
– F
c
/ΣF .
o
2
b
c
2
2
2 2 1/2
o
 – F
c
) /ΣwF
o
 ]
.
1/2
2
o
 – F ) /(Nobs – Nparam)] .
c
1
2

Scheme and Figure Captions:
Scheme 1. Synthesis and reactivity of ruthenium complexes with 2-(methylthiophenyl)salicylaldimine
(
ONS-L) ligands. Reagents and conditions: (i) [Ru(PPh
3
)
3
Cl
2
] / Et
3
N, THF, r.t.; (ii) [Ru(CO)
2
Cl
2
],
DMF / EtOH, 90 °C; (iii) [Ru(CO)
2
Cl
2
], DMF / CH
2
Cl
2
, in air, 90 °C; (iv) RuCl
3
⋅3H
2
O / Et
3
N, at
*
reflux; (v) [Cp
2
Ru] / NaOH, THF / EtOH, at reflux; (vi) AgNO
3
, MeOH / H O, at reflux.
2
Fig. 1. Molecular structure of [Ru(ONS-L)(PPh
3
)
2
Cl]⋅CH
3
OH⋅2.75H O 1, solvents are omitted for clarity.
2
Thermal ellipsoids are shown at the 40% probability level.
2
Fig. 2. Molecular structure of [Ru(CO) (ONS-L)Cl] 2. Thermal ellipsoids are shown at the 40% probability
level.
2
Fig. 3. Molecular structure of [Ru(CO)(ONS-L)Cl ] 3. Thermal ellipsoids are shown at the 40% probability
level.
−
Fig. 4. Molecular structure of [Ru(ONS-L)Cl
3
] anion in 4. Thermal ellipsoids are shown at the 40%
probability level.
6
Fig. 5. Molecular structure of [Cp*Ru(η -1,2,3,4-Me
4
C
6
H
2
)][Ru(ONS-L)Cl
3
2
]⋅CH Cl2 5, solvents are omitted
for clarity. Thermal ellipsoids are shown at the 40% probability level.
Fig. 6. Molecular structure of [Ru
2
(ONS-L)(µ-ONS-L)
2
Cl]⋅CH Cl2 6, solvents are omitted for clarity.
2
Thermal ellipsoids are shown at the 40% probability level.
13

Scheme 1
N
N
S
O
S
O
RuII
RuIII
Cl
Ph3P
Cl
Cl
PPh
3
CO
3
1
(
iii)
(i)
N
N
CH
HO
N
S
O
(
ii)
RuII
S
OH
S
Cl
CO
CH3
CO
(vi)
2
N
RuIII
Cl
N
N
S
(
v)
(vi)
S
S
Cl
S
O
S
O
O
O
RuII
N
RuII
Ru
RuIII
N
Cl
Cl
Cl
Cl
O
Cl
5
4
6
14

Fig. 1.
Fig. 2.
15

Fig. 3.
Fig. 4.
16

Fig. 5.
Fig. 6.
17

(
Graphical Abstract)
Ruthenium complexes bearing tridentate 2-(methylthio)phenylsalicylaldimine
Schiff-base ligands
Chang-Jiu Wang, Hui Lin, Xin Chen, Ai-Quan Jia, and Qian-Feng Zhang*
Six ruthenium(II) and ruthenium(III) complexes bearing tridentate monoanionic Schiff base ligands were
synthesized and characterized by spectroscopic methods and single-crystal X-ray diffraction.
18

Highlights
►
►
►
Six ruthenium(II)/(III) complexes bearing ONS-Schiff-base ligands were synthesized.
All the synthesized complexes were characterized by X-ray crystallography.
The ruthenium complex was tested as catalyst for oxidation of 1-phenylethanol.
19