Syntheses, structures and reactivity of dinuclear organoruthenium-nickel complexes with N,N′-bis(2-thiobenzylidene)-1,2-phenylenediaminato (tsalphen) ligand

Article abstract of DOI:10.1016/j.jorganchem.2018.01.015

Treatment of metalloligand [Ni(tsalphen)] (tsalphen = N,N′-bis(2-thiobenzylidene)-1,2-phenylenediaminato) with [(η⁶-p-cymene)RuCl(μ-Cl)]₂ or [CpRu(PPh₃)₂Cl] afforded cationic “Ni(μ-S)₂Ru” bimetallic complexes [(η⁶-p-cymene)Ru{Ni(tsalphen)}(MeCN)](OTf)₂ (1) and [CpRu{Ni(tsalphen)}(PPh₃)]₂(NiCl₄)?4MeOH (2), respectively, which are characterized by single-crystal X-ray diffraction, and their catalytic activity for acetalation of benzaldehyde in the presence of H₂ was also investigated.

Full text of DOI:10.1016/j.jorganchem.2018.01.015

Accepted Manuscript
Syntheses, structures and reactivity of dinuclear organoruthenium-nickel complexes
with N,N′-bis(2-thiobenzylidene)-1,2-phenylenediaminato (tsalphen) ligand
Ai-Quan Jia, Li-Hua Tang, Xian-Ping Dong, Zhifeng Xin, Qian-Feng Zhang
PII:
S0022-328X(18)30015-9
10.1016/j.jorganchem.2018.01.015
JOM 20253
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 3 November 2017
Revised Date: 3 January 2018
Accepted Date: 14 January 2018
Please cite this article as: A.-Q. Jia, L.-H. Tang, X.-P. Dong, Z. Xin, Q.-F. Zhang, Syntheses, structures
and reactivity of dinuclear organoruthenium-nickel complexes with N,N′-bis(2-thiobenzylidene)-1,2-
phenylenediaminato (tsalphen) ligand, Journal of Organometallic Chemistry (2018), doi: 10.1016/
j.jorganchem.2018.01.015.
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ACCEPTED MANUSCRIPT
Syntheses, structures and reactivity of dinuclear organoruthenium-
nickel complexes with N,N’-bis(2-thiobenzylidene)-1,2-
phenylenediaminato (tsalphen) ligand
Ai-Quan Jia, Li-Hua Tang, Xian-Ping Dong, Zhifeng Xin, and Qian-Feng Zhang*
Institute of Molecular Engineering and Applied Chemistry, Anhui University of Technology,
Ma’anshan, Anhui 243002, P. R. China
Abstract
Treatment of metalloligand [Ni(tsalphen)] (tsalphen = N,N’-bis(2-thiobenzylidene)-1,2-
6
phenylenediaminato) with [(
η
-p-cymene)RuCl(
µ
-Cl)]
2
or [CpRu(PPh
3
)
2
Cl] afforded cationic “Ni(µ-
(1) and
6
S) Ru” bimetallic
2
complexes
[(
η
-p-cymene)Ru{Ni(tsalphen)}(MeCN)](OTf)
2
[
CpRu{Ni(tsalphen)}(PPh )] (NiCl )⋅4MeOH (2), respectively, which are characterized by single-
3 2 4
crystal X-ray diffraction, and their catalytic activity for acetalation of benzaldehyde in the presence of
was also investigated.
H
2
2
Keywords: Ni(µ-S) Ru complex; Heterobimetallic; Metalloligand; Organoruthenium complex;
Catalytic activity
_
*
__________________
Corresponding author. E-mail: zhangqf@ahut.edu.cn (Q.-F. Zhang).
1

ACCEPTED MANUSCRIPT
1
. Introduction
Bioinspired designs thus have led to new catalytic systems for hydrogen production or uptake that
minic all or part of the structure of the Fe−Fe hydrogenase active site in the past decades [1].
Furthermore, dinuclear Ni-Fe complexes with significant catalytic activity for the hydrogen evolution
+
reaction have been reported recently [2]. As a unique molecular catalyst for H
2
/H interconversion,
hydrogenases are competitive with platinum metal. As a result, people have paid much attention on the
synthesis of a great variety of biomimetic complexes with the aim of both better understanding the
catalytic mechanism of native [NiFe] and [NiRu] hydrogenases at the molecular level and developing
new electrocatalysts to be used in electrolytic/photosynthetic cells for hydrogen production [3]. Since
the active sites of the [NiFe] enzymes consist of dithiolate-linked Ni-Fe center bearing little
resemblance to known compounds, quite a few Ni-Fe complexes with the structural characterization
have been well documented. Typically, such bimetallic complexes are prepared by the interaction of
iron reagents with diaminidithiolates of nickel(II), as these diamini-dithiolate building blocks comprise
a fairly large class of complexes [4].
As known, ruthenium can easily accommodate both hard and soft ligands including dihydrogen or
hydride. Many ruthenium complexes as well as one diruthenium analogue of the iron-only hydrogenase
2 2
active site are known to catalytically activate hydrogen [5]. Since Darensbourg showed that {NiN S }
moieties can serve as ligands in the same way as diimines [6], it was tempted to use such moieties to
prepare and investigate nickel-ruthenium complexes [7]. Notably, Ogo and his coworkers reported the
II
II
II
II
6
NiRu-based, H
2
O-coordinated bis(µ-thiolato)Ni Ru complex [(Ni L)Ru (H
2
O)(η
-C
6
Me
6
3 2
)](NO )
II
II
(
A), which successfully reacted with H
2
in water to give a hydrido bridged bis(
µ
-thiolato)Ni Ru
II
II
6
complex [(Ni L)(H
2
O)(
µ
-H)Ru (
η
-C
6
6 3
Me )](NO ) (B), where L = N,N′-dimethyl-N,N′-bis(2-
mercaptoethyl)-1,3-propanediamine [8]. Afterwards, Ogo group reported several other NiRu-based
complexes by altering the organoruthenium moieties, such as the aromatic rings, in order to shed light
on the structure-function relationships in this class of catalysts, and to gain more insight into the
reaction activity of the dinuclear complexes with H [3b,7b,c]. Herein, we described the employment of
2
metalloligand [Ni(tsalphen)] (Chart 1) to prepare new dinuclear organoruthenium-nickel complexes,
with the tetradentate rigid ligand around the nickel ion and the organometallic ligand set of the
ruthenium center. The reactivity of the structurally defined complexes towards H was also initially
2
investigated.
2

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2
. Experimental
2
.1. General
All synthetic manipulations were carried out under dry nitrogen by standard Schlenk techniques.
Solvents were purified, distilled and degassed prior to use. Published procedures were followed in the
preparation of [Ni(tsalphen)] (tsalphen = N,N’-bis(2-thiobenzylidene)-1,2-phenylenediaminato) [9],
6
[
(η
-p-cymene)RuCl(
µ
-Cl)]
2
[10], and [CpRu(PPh
3
)
2
Cl] (Cp = cyclopentadienyl) [11]. AgOTf (OTf =
OSO CF ) was purchased from Alfa Aesar Ltd and used without further purification. NMR spectra
2
3
1
31
were recorded on a Bruker ALX 400 spectrometer operating at 400 and 162 MHz for H and P,
1
respectively. Chemical shifts (
δ
, ppm) were reported with reference to SiMe
4
( H) and 85% H
3
PO
4
3
1
(
P). Infrared spectra (KBr) were recorded on a Perkin-Elmer 16 PC FT-IR 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. GC-MS
experiments were performed on a Shimadzu GC-MS 2010 PLUS instrument.
6
2
.2. Preparation of [(
η
2
-p-cymene)Ru{Ni(tsalphen)}(MeCN)](OTf) (1)
6
To a solution of [(
η
-p-cymene)RuCl(
µ
-Cl)] (61.2 mg, 0.10 mmol) in methanol (5 mL) was
2
added a solution of AgOTf (102.4 mg, 0.40 mmol) in tetrahydrofuran (THF) (3 mL), and then the
mixture was stirred for 20 min at room temperature. The red filtrate was added to the solution of
[
Ni(tsalphen)] (63.6 mg, 0.20 mmol) in THF (10 mL), the resulting orange solution was continuously
stirred overnight at room temperature and then concentrated ca. 1 mL. Slow addition of diethyl ether
gave an orange precipitate, which was recrystallized from acetonitrile/diethyl ether. Yield: 58 mg, 83%
(
based on Ru). Single crystals suitable for X-ray crystallography were obtained by slow diffusion of
1
diethyl ether into an acetonitrile solution of the complex. H NMR (400 MHz, DMSO-d
6
): δ 1.17 (d, J
=
6.8 Hz, 6H, CH(CH ) ), 2.21 (s, 3H, ArCH ), 2.88 (sept, 1H, CH(CH ) ), 6.27 (d, J = 6.4 Hz, 4H, p-
3
2
3
3 2
iPrC
6
H
4
Me), 6.68 (d, J = 6.4 Hz, 4H, p-iPrC
6
4
H Me), 6.98-7.08 (m, 2H, ArH), 7.18-7.23 (m, 2H, ArH),
13
7
.30-7.38 (m, 2H, ArH), 7.45-7.56 (m, 2H, ArH), 7.78-7.83 (m, 4H, ArH), 8.90 (s, 2H, N=CH). C
NMR (400 MHz, DMSO-d ): 19.4 (CH(CH ) ), 22.6 (ArCH ), 31.1 (CH(CH ) ), 81.0 (cymene), 81.8
6
3 2
3
3 2
(
cymene), 97.2 (cymene), 101.7 (cymene), 118.3 (Ar), 124.6 (Ar), 126.0 (Ar), 129.5 (Ar), 132.8 (Ar),
-1
1
33.6 (Ar), 134.9 (Ar), 135.5 (Ar), 140.6 (Ar), 168.3 (N=CH). IR (KBr disc, cm ): v 2373(s), vC=N
C≡N
3

ACCEPTED MANUSCRIPT
6
+
6
1
603(m). FAB-MS (MeCN): m/z 681.5 [(
η
-p-cymene)Ru{Ni(tsalphen)}(MeCN)] , 640.4 [(
η
-p-
+
cymene)Ru{Ni(tsalphen)}] . Anal. Calc. for C H N O F S NiRu: C, 41.68; H, 3.20; N, 4.29. Found:
3
4
31
3
6 6 4
C, 41.45; H, 3.17; N, 4.22.
2
.3. Preparation of [CpRu{Ni(tsalphen)}(PPh )] (NiCl )⋅ 4MeOH (2)
3 2 4
3 2
A mixture of [Ni(tsalphen)] (81.0 mg, 0.30 mmol) and [CpRu(PPh ) Cl] (72.6 mg, 0.15 mmol) in
acetonitrile (15 mL) was heated at reflux overnight, during which there was a color change from dark
red to dark brown. The solvent was removed in vacuo, and the residue was washed with hexane and
diethyl ether. Recrystallization from acetonitrile/methanol/diethyl ether afforded black block-shaped
crystals of [CpRu{Ni(tsalphen)}(PPh )] (NiCl )⋅4MeOH (2) in a week. Yield: 85 mg, 74% (based on
3
2
4
1
Ru). H NMR (400 MHz, DMSO-d ): δ 5.61 (s, 5H, Cp), 6.95-7.83 (m, 27H, ArH), 8.87 (s, 2H, N=CH).
6
3
1
1
13
P{ H} NMR (162 MHz, DMSO-d ): δ 51.9. C NMR (400 MHz, DMSO-d ): 78.7 (Cp), 118.9 (Ar),
6
6
1
25.3 (Ar), 126.7 (Ar), 130.0 (Ar), 130.5 (Ar), 133.8 (Ar), 134.0 (Ar), 134.7 (Ar), 136.0 (Ar), 136.9
-1
(
Ar), 139.2 (Ar), 142.1 (Ar), 170.1 (N=CH). IR (KBr disc, cm ): vC=N 1600 (m). FAB-MS (MeCN):
+
+
m/z 831.6 [CpRu{Ni(tsalphen)}(PPh )] , 569.3 [CpRu{Ni(tsalphen)}] . Anal. Calc. for
3
C H N Cl P S Ni Ru ⋅4(CH O): C, 54.27; H, 4.05; N, 2.81. Found: C, 54.13; H, 4.11; N, 2.85.
86
64
4
4
2
4
3
2
4
2
.4. X-ray crystallography
A summary of crystallographic data and experimental details for complexes 1 and 2 are listed in
Table 1. Intensity data were collected on a Bruker SMART APEX 2000 CCD diffractometer using
graphite-monochromated Mo-Kα radiation ( = 0.71073 Å) at 293(2) K. The data was corrected for
λ
absorption using the program SADABS [12]. Structures were solved by the direct methods and refined
2
by full-matrix least-squares on F using the SHELXTL software package [13]. All non-hydrogen atoms
were refined anisotropically except for O3S, O1S and C1S atoms of the solvent molecules due to
disorder. Hydrogen atoms in the phenyl and other organic moieties were treated as idealized
contributions (C −H = 0.96 and C −H = 0.93 Å). One methanol solvent molecule in 2 was refined
sp3
sp2
without hydrogen atoms.
2
.5. Typical procedure for acetalation of benzaldehyde with ethanol in the presence of NiRu complexes
and H
2
4

ACCEPTED MANUSCRIPT
The catalyst solution was prepared by dissolving complex 1 or 2 (0.005 mmol) in acetonitrile (60
mL). Under 1 atm hydrogen atmosphere, a mixture of aldehyde (2.0 mmol), 6 mL of the catalyst
solution (0.0005 mmol), and ethanol (12 mL) was stirred at room temperature for four hours. After the
reaction was complete, the reaction mixture was concentrated under reduced pressure and subjected to
elimination of catalyst by silica gel column chromatography using ethyl acetate/n-hexane (v:v = 1:5)
mixed solvents as eluent to afford the product, which was identified through GC-MS analysis.
3
. Results and discussion
The metalloligand [Ni(tsalphen)] was prepared by an alternative method involving four synthetic
2 2
steps starting from 2-bromobenzaldehyde. To our best knowledge, the reported [NiN S Ru] complexes
usually comprise two kinds of flexible ligands, i.e. N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)-1,3-
propanediamine and 1,5-bis(2-mercapto-2-methylpropyl)-1,5-diazacyclooctane [3a,8]. However, the
6
rigid and conjugate [Ni(tsalphen)] has attracted less attention. The [(
η
-p-cymene)Ru(MeOH)
3
](OTf)
2
6
may be prepared in situ by the dechlorination of [
η
-p-cymene)RuCl(
µ
-Cl)] in the prescence of AgOTf
2
6
in methanol solution. Treatment of a THF solution of [Ni(tsalphen)] with [(
η
-p-cymene)-
6
Ru(MeOH) ](OTf)2 at room temperature furnished orange [(
η
-p-cymene)Ru{Ni(tsalphen)}-
3
(
MeCN)](OTf) (1) in a relatively high yield. The cationic complex 1 is air-stable in the solid state but
2
easily oxygenates when exposed to air in solution for a couple of hours. The phosphine ligands in
[
[
(
CpRu(PPh ) Cl] are known to be labile, and this encouraged us to carry on the reaction of
3 2
Ni(tsalphen)] and [CpRu(PPh
3
)
2
Cl], which afforded the PPh
3
adduct [CpRu{Ni(tsalphen)}-
PPh )] (NiCl )⋅4MeOH (2), isolated as black crystals (Scheme 1). By the comparison of complex 1,
3
2
4
complex 2 is relatively air-stable both in solution and in the solid state.
The IR spectra of complexes 1 and 2 clearly show medium bands of vC=N in metalloligand
−1
−1
moiety [Ni(tsalphen)] at 1603 and 1600 cm , respectively, which red shifted about 10 cm compared
−1
with that in free [Ni(tsalphen)] (1590 cm ) [9c]. The stretching vibration of the C≡N of CH CN was
3
-1
observed in the absorption band at 2373 cm , which was similar to those of CH CN-coordinated Ru
3
6
complexes [(HMB)Ru(dppf)(CH
3
CN)](PF
6
)
2
(HMB =
η
-C
6
Me
6
, dppf = 1,1'-bis(diphenylphosphino)-
-1
-1
1
ferrocene, 2363 cm ) and [(HMB)Ru(CH CN) Cl](PF ) (2359 cm ) [14]. The H NMR spectra of
3
2
6
5

ACCEPTED MANUSCRIPT
3
1
complexes 1 and 2 both show a singlet for the CH=N group proton at around 8.90 ppm. The P NMR
spectrum of complex 2 displays PPh signal at 51.9 ppm as a singlet, comparable to that in the related
3
i
complex [CpRu(PPh
3
)S
2
CNSi Pr
3
(1-Naphth)] (53.7 ppm) [15]. The positive ion FAB mass spectra of 1
6
and 2 display the expected peaks which corresponded to the cation ions ([(
η
-p-cymene)Ru-
+
+
6
+
{
Ni(tsalphen)}(MeCN)] or [CpRu{Ni(tsalphen)}(PPh )] , and [(
η
-p-cymene)Ru{Ni(tsalphen)}] or
3
+
[
CpRu{Ni(tsalphen)}] with the characteristic isotopic distribution patterns.
6
The molecular structures of [(
η
-p-cymene)Ru{Ni(tsalphen)}(MeCN)](OTf)2 (1) and
[
CpRu{Ni(tsalphen)}(PPh )] (NiCl )⋅4MeOH (2) have been established by single crystal X-ray
3
2
4
diffraction analysis. Complexes 1 and 2 crystallize in monoclinic P2 /c and triclinic P
ī
space groups,
1
6
2+
respectively. The structures of cationic part [(
η
-p-cymene)Ru{Ni(tsalphen)}(MeCN)] in 1 and
+
[
CpRu{Ni(tsalphen)}(PPh )] in 2 are depicted in Figs. 1 and 2, respectively. The structures of both 1
3
and 2 contain a NiS
2
Ru butterfly core, in which nickel atom and ruthenium atom are located in wing,
joined by a pair of bidentate thiolato ligands as the body of the butterfly. The nickel atom adopts a
square planar geometry with the tetradentate ligand tsalphen, the bond angles of N(1)−Ni(1)−S(1) and
N(2)−Ni(1)−S(2) in 1 are 176.36(10)° and 177.59(10)°, respectively. The bond angles of
N(2)−Ni(1)−S(1) and N(1)−Ni(1)−S(2) in 2 are 177.80(8)° and 176.49(6)°, respectively, almost the
same to those in 1. The ruthenium atoms in 1 and 2 both adopt a distorted-octahedral coordination,
which is surrounded by one aromatic ring, one metalloligand [Ni(tsalphen)], and one
acetonitrile/triphenylphosphine ligand. The Ni−S−Ru angles {84.41(4) and 84.39(4)°} of 1 are
significantly larger than those of 2 {77.89(3) and 77.06(3)°}. Due to the larger angles, the distance
{
3.0760(6) Å} between Ni and Ru in 1 is obviously longer than that in 2 {2.8828(7) Å}, possibly
indicating triphenylphosphine coordinated ruthenium species in complex 2 being more stable. In the
II
II
6
hydrido-bridged Ni(µ-H)(µ-S)
2 2 6 6 3
Ru complex [(Ni L)(H O)(µ-H)Ru (η -C Me )](NO ) (L = N,N′-
dimethyl-N,N′-bis(2-mercaptoethyl)-1,3-propanediamine), the Ni⋅⋅⋅Ru distance is 2.739(3) Å [8]. The
ruthenium center in 1 features an CH
3
CN ligand with a Ru−N−C angle of 174.0(4)° and Ru−N distance
II
of 2.082(4) Å, which are normally compared with other bimetallic [Ni(µ-S)Ru] complexes [Ni (µ-
II
6
SR) Ru (CH CN)(
η
-C Me )](NO )
3 2
[(µ-SR)2
=
N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)-1,3-
2
3
6
6
propanediamine, 165.5(2)°, 2.059(2) Å] [7a] and [Cp*Ru(Ni(bme*-daco))(NCMe)]OTf (Cp* =
pentamethylcyclodiene, bme*-daco = [1,5-bis(2-mercapto-2-methylpropyl)-1,5-diazacyclooctane],
1
72.2(3)°, 2.051(4) Å) [3a]. The ruthenium center in 2 features a triphenylphosphine ligand with a
6

ACCEPTED MANUSCRIPT
Ru−P bond length of 2.3311(10) Å, similar to that in related ruthenium(II) complex
i
[
CpRu(PPh )S CNSi Pr (1-Naphth)] (2.269(2) Å) [15]. The S−Ru−S bond angles in 1 and 2 are
3
2
3
7
1.21(3)° and 71.77(3)°, respectively, which are in good agreement with those in other reported
[
NiN S Ru] complexes (71.21−75.71°) [3a,8].
2 2
II
II
6
+
As known, Ogo reported that [(Ni L)(H
2 6 6
O)(µ-H)Ru (η -C Me )] with a bridging hydrido
ligand could be isolated from the heterolytic cleavage of H by a dinuclear NiRu aqua complex
2
II
II
6
2+
[
(Ni L)(H O)Ru (η -C Me )] (L = N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)-1,3-propanediamine) in
2 6 6
water [8]. Complex 2 was tested as the catalyst in the reaction of benzaldehyde and ethanol under
dihydrogen atmosphere. Through analysis of GC-MS spectra (see Fig. 3) and comparison with standard
compounds, the retention times of 2.171 and 3.242 min correspond to molecular weight of 106 and 180
-1
g·mol , which in turn correspond to molecular formula of C
7 6 16 2
H O and C11H O , respectively. As a
result, the species are supposed to be benzaldehyde (C H CHO) and benzaldehyde diethyl acetal
6
5
(
C H CH(OCH CH ) ), respectively, based on the designed reaction. This indicates that acetalation of
6 5 2 3 2
benzaldehyde took place in the presence of dihydrogen and dinuclear organoruthenium-nickel complex
+
2
in ethanol solvent. The acetalation reaction usually proceeds with H as the catalyst. Controlled
reaction without dihydrogen did not give the acetal compound, suggesting dihydrogen being the source
+
of H . PH measurements were performed on the reaction process, which showed that the pH of the
solution decreased (from pH 6.5 to pH 5.1), indicating the heterolytic H cleavage [8,16]. However, we
2
did not isolate the expected metal hydride complexes after much effort.
It could be seen from Fig. 3 that the conversion of such acetalation reaction was not high. The
impact of temperature, reaction time and the amount of catalyst was systematically investigated (Table
o
o
2
1
). When the temperature increased from 0 C to 40 C, the conversion of benzaldehyde increased from
.72% to 14.73%, suggesting the higher temperature benefits the reaction. However, when the
o
temperature is 60 C, no obvious increase of the conversion was achieved (entry 13). The reaction time
o
also had influence on the reaction. For example, when the reaction was carried at 40 C, the conversion
was 14.37% after 1h, while it reached 25.21% after 5 h, though more reaction time led to little increase
(
entry 12). As expected, the conversion increased with the increased amount of dinuclear NiRu
complex (entry 14). When complex 1 was employed to initiate the reaction, the product benzaldehyde
diethyl acetal was also observed. The conversions in this catalytic system are compared to that in other
transition metal catalyzed ethanolysis of benzaldehyde [17]. It is noted that the CH
3
CN ligand of
7

ACCEPTED MANUSCRIPT
II
II
6
II
II
[
(Ni L)Ru (CH
3
CN)(η
-C
6
6 3 2 2
Me )](NO ) could be easily exchanged for H O to give the aqua Ni Ru
II
II
6
complex [(Ni L)Ru (H O)(
η
-C Me )](NO ) which converted to be the hydride metal complex after
2
6
6
3 2,
continuous H bubbling [7a]. Possibly heterolytic cleavage of H by the dinuclear NiRu complexes
2
2
with [Ni(tsalphen)] took place during the acetalation reaction based on the previous research by Ogo,
who successfully isolated a paramagnetic dinuclear nickel-ruthenium complex with a bridging hydrido
ligand from the heterolytic cleavage of H by a dinuclear NiRu aqua complex [8].
2
In summary, two thiolate-bridged bimetallic nickel-ruthenium complexes were synthesized and
characterized. Isolation of the two nickel-ruthenium complexes suggests that [Ni(tsalphen)] could also
be employed as a metalloligand to construct heterobimetallic Ni(µ-S) Ru complexes. X-Ray diffraction
2
studies establish the Ni⋅⋅⋅Ru distances in 1 (3.0760(6) Å) and 2 (2.8825(12) Å) are slightly shorter than
those in related bimetallic nickel-ruthenium complexes with flexible [N S ] ligands [3a, 3b, 7d]. The
2
2
2
triphenylphosphine ligand may stabilize the Ni(µ-S) Ru complex 2, indicated by its shorter Ni⋅⋅⋅Ru
distance and more stability both in solution and solid state. Complexes 1 and 2 could catalyze
acetalation of benzaldehyde with ethanol in the presence of hydrogen.
4
. Supplementary material
6
Crystallographic data for [(
η
-p-cymene)Ru{Ni(tsalphen)}(MeCN)](OTf)
2
(1) and
[
CpRu{Ni(tsalphen)}(PPh )] (NiCl )⋅4MeOH (2) been deposited with the Cambridge Crystallographic
3 2 4
Data Centre as supplementary publication nos. CCDC 1578841 and 1578842, respectively. Copies of
the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK [fax: (+44)1233-336-033; e-mail: deposit@ccdc.cam.ac.uk].
Acknowledgements
This project was supported by the Natural Science Foundations of China (21372007 and
2
1471003).
References
8

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[
1] (a) J.W. Peters, W.N. Lanzilotta, B.J. Lemon, L.C. Seefeldt, X-ray crystal structure of the Fe-only hydrogenase
(
CpI) from clostridium pasteurianum to 1.8 angstrom resolution. Science 282 (1998) 1853-1858;
(
(
b) Y. Oudart, V. Artero, J. Pécaut, C. Lebrun, M. Fontecave, Dinuclear nickel-ruthenium complexes as functional
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6] D.K. Mills, Y.M. Hsiao, P.J. Farmer, E.V. Atnip, J.H. Reibenspies, M.Y. Darensbourg, Applications of the N2S2
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1
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Table 1.
Crystallographic data and experimental details for [(
6
η
-p-cymene)Ru{Ni(tsalphen)}(MeCN)](OTf) (1) and
2
[
CpRu{Ni(tsalphen)}(PPh )] (NiCl )⋅4MeOH (2).
3
2
4
complex
1
2
empirical formula
formula weight
crystal system
a (Å)
C H N O F S NiRu
C H N O P Cl S Ni Ru
2
34
31
3
6
6
4
90 80
4
4
2
4
4
3
979.64
1991.83
monoclinic
11.4100(7)
20.9518(13)
16.6336(10)
triclinic
12.255(2)
17.373(3)
22.183(3)
74.704(3)
74.397(3)
70.397(3)
4214.3(13)
b (Å)
c (Å)
α
β
γ
(°)
(°)
(°)
105.268(1)
3
V (Å )
3836.1(4)
space group
P2 /c
P
ī
1
Z
4
2
-
3
Dcalc (g cm )
temperature (K)
F(000)
1.696
296(2)
1976
1.179
23770
8745
497
1.570
296(2)
2028
-1
µ
(Mo-K
α
) (mm )
1.326
26211
18452
1011
total refln
independent refln
parameters
Rint
0.0307
0.0516
a
b
R1 , wR2 (I > 2
σ
(I))
0.0475, 0.1320
0.0707, 0.1492
1.065
0.0693, 0.1572
0.1737, 0.2032
0.935
R1, wR2 (all data)
c
GoF
a
R1 =  F – F  /F .
wR2 = [w(F
GoF = [w(F  – F ) /(N – Nparam)] .
o
c
o
b
c
2
2
c
2
2
2 1/2
o
 – F
) /wF  ] .
o
2
1/2
o
c
obs
1
2

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Table 2.
Acetalization of benzaldehyde with ethanol in the presence of Ni-Ru complexes and H .
a
2
entry
catalyst
temperature/°C
time/h
conversion/%
1.72
1
2
3
4
5
6
7
8
9
2
2
2
2
2
2
2
2
2
2
2
2
2
0
1
1
2
3
4
5
1
2
3
4
5
10
5
5
5
15
15
15
15
15
40
40
40
40
40
40
60
40
40
2.79
6.16
10.52
14.21
16.29
14.37
18.51
20.29
23.16
25.21
26.73
25.54
37.02
24.07
1
0
1
1
1
1
1
1
2
3
4
5
b
2
1
a
b
Reactions were monitored by TLC/GC.
The amount of catalyst is 0.001 mmol (twice of that in entry 11).
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3

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Chart 1. The structures of two [NiN S ] metalloligands in NiRu complexes.
2
2
6
Scheme 1. Synthesis of two dinuclear organoruthenium-nickel complexes [(η -p-
cymene)Ru{Ni(tsalphen)}(MeCN)](OTf) (1) and [CpRu{Ni(tsalphen)}(PPh )] (NiCl )⋅4MeOH (2).
2
3
2
4
6
Reagents and conditions: (i) [
η
-p-cymene)RuCl(µ-Cl)] / AgOTf / THF, r. t.; (ii) [CpRu(PPh ) Cl] /
2 3 2
MeCN, reflux.
1
4

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6
Fig. 1. Molecular structure of the cation of [(
η
-p-cymene)Ru{Ni(tsalphen)}(MeCN)](OTf)
2
1, with
thermal ellipsoids drawn at the 40% probability level. Hydrogen atoms and anions are omitted for
clarity. Selected bonds (Å) and angles (°): Ru(1)-N(3) 2.082(4), Ru(1)-C(7) 2.173(5), Ru(1)-C(3)
2
.183(4), Ru(1)-C(6) 2.201(5), Ru(1)-C(4) 2.207(4), Ru(1)-C(2) 2.208(5), Ru(1)-C(5) 2.221(5), Ru(1)-
S(2) 2.4086(10), Ru(1)-S(1) 2.4169(10), Ru(1)-Ni(1) 3.0760(6), Ni(1)-N(2) 1.890(3), Ni(1)-N(1)
1
8
.896(3), Ni(1)-S(1) 2.1529(11), Ni(1)-S(2) 2.1633(11); S(2)-Ru(1)-S(1) 71.21(3), N(2)-Ni(1)-N(1)
5.60(14), S(1)-Ni(1)-S(2) 81.21(4), N(1)-Ni(1)-S(1) 176.36(10), N(2)-Ni(1)-S(2) 177.59(10), Ni(1)-
S(1)-Ru(1) 84.41(4), Ni(1)-S(2)-Ru(1) 84.39(4).
1
5

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Fig. 2. Molecular structure of one anion of [CpRu{Ni(tsalphen)}(PPh )] (NiCl )⋅4MeOH 2, with
3
2
4
thermal ellipsoids drawn at the 40% probability level. Hydrogen atoms, the other cation and the counter
anion are omitted for clarity. Selected bonds (Å) and angles (°): Ru(1)-P(1) 2.3311(10), Ru(1)-S(1)
2
.4087(8), Ru(1)-S(2) 2.4345(8), Ru(1)-Ni(1) 2.8828(7), Ni(1)-N(1) 1.901(3), Ni(1)-N(2) 1.918(2),
Ni(1)-S(1) 2.1678(8), Ni(1)-S(2) 2.1826(10); S(1)-Ru(1)-S(2) 71.77(3), N(1)-Ni(1)-N(2) 85.41(10),
S(1)-Ni(1)-S(2) 81.47(4), N(2)-Ni(1)-S(1) 177.80(8), N(1)-Ni(1)-S(2) 176.49(6), Ni(1)-S(1)-Ru(1)
7
7.89(3), Ni(1)-S(2)-Ru(1) 77.06(3).
(a)
(b)
77
105
1
35
51
2
3
4
5
30
40
50
60
70
80
90 100 110 120 130 140 150
Time
m/z
(
a)
(b)
Fig. 3. GC-MS analysis of product from reaction of benzaldehyde and ethanol under H2
atmosphere catalyzed by complex 2, (a) GC; (b) MS.
1
6

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For Table of Contents
Synopsis
Syntheses, structures and reactivity of dinuclear organoruthenium-nickel complexes with
N,N’-bis(2-thiobenzylidene)-1,2-phenylenediaminato (tsalphen) ligand
Ai-Quan Jia, Li-Hua Tang, Xian-Ping Dong, Zhifeng Xin, and Qian-Feng Zhang*
Two cationic bimetallic organoruthenium-nickel Ni(µ-S)
Ni(tsalphen)] have been synthesized and characterized by X-ray crystallography, they could catalyze
acetalation of benzaldehyde with ethanol in the presence of H
2
Ru complexes containing metalloligand
[
2
.
1
7

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Highlights
►
►
►
Two dinuclear nickel-ruthenium complexes with tsalphen ligand were synthesized.
2
The Ni(µ-S) Ru complexes were characterized by single crystal X-ray crystallography.
2
They catalyze acetalation of benzaldehyde with ethanol in the presence of H .
1