Syntheses, characterization and reactivity of dinuclear ruthenium-nickel complexes with hexane-2,5-dione bis(thiosemicarbazonato) ligands

Article abstract of DOI:10.1016/j.jorganchem.2018.07.006

Treatment of hexane-2,5-dione bis(thiosemicarbazones) ([CH₃?C{= N?NH?C(=S)?NHR}?CH₂]₂, R = H, L¹H₂; CH₃, L²H₂?Me; CH₂CH₃, L³H₂?Et; C₆H₅, L⁴H₂?Ph) with nickel(II) acetate hydrate in refluxing ethanol gave a series of Ni^IIN₂S₂ metalloligands [Ni(L-R)] for the generation of hetero-bimetallic complexes. The reaction of equal mole each of [Ni(L¹)], [Ni(L²?Me)], [Ni(L³?Et)], or [Ni(L⁴?Ph)] with [RuCl₂(dmso)₄] (dmso = dimethyl sulfoxide) at reflux resulted in isolation of neutral dinuclear ruthenium-nickel complexes [RuCl₂{(Ni(L¹)}(dmso)₂] (1), [RuCl₂{(Ni(L²?Me)}(dmso)₂] (2), [RuCl₂{(Ni(L³?Et)}(dmso)₂] (3), and [RuCl₂{(Ni(L⁴?Ph)}(dmso)₂] (4). Interaction of [Ni(L-R)] with [CpRu(PPh₃)₂Cl] (Cp^? = cyclopentadienyl) at room temperature led to formation of cationic dinuclear organoruthenium-nickel complexes [CpRu{(Ni(L¹)}(PPh₃)]Cl (5), [CpRu{(Ni(L²?Me)}(PPh₃)]Cl (6), [CpRu{(Ni(L³?Et}(PPh₃)]Cl (7), and [CpRu{(Ni(L⁴?Ph}(PPh₃)]Cl (8). New bimetallic ruthenium-nickel complexes 1–8 have been characterized spectroscopically, of which molecular structures of three complexes [RuCl₂{(Ni(L²?Me)}(dmso)₂]·CH₂Cl₂ (2·CH₂Cl₂), [CpRu{(Ni(L²?Me)}(PPh₃)]Cl?EtOH (6?EtOH), and [CpRu{(Ni(L³?Et}(PPh₃)]Cl (7?H₂O) have been established by single-crystal X-ray crystallography. Their catalytic activities for the acetalation of benzaldehyde in the presence of molecular H₂ have been also investigated in this paper.

Full text of DOI:10.1016/j.jorganchem.2018.07.006

Accepted Manuscript
Syntheses, characterization and reactivity of dinuclear ruthenium-nickel complexes
with hexane-2,5-dione bis(thiosemicarbazonato) ligands
Duo-Wen Fang, Ai-Quan Jia, Xian-Ping Dong, Zhifeng Xin, Qian-Feng Zhang
PII:
S0022-328X(18)30300-0
10.1016/j.jorganchem.2018.07.006
JOM 20493
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 3 May 2018
Revised Date: 3 July 2018
Accepted Date: 6 July 2018
Please cite this article as: D.-W. Fang, A.-Q. Jia, X.-P. Dong, Z. Xin, Q.-F. Zhang, Syntheses,
characterization and reactivity of dinuclear ruthenium-nickel complexes with hexane-2,5-dione
bis(thiosemicarbazonato) ligands, Journal of Organometallic Chemistry (2018), doi: 10.1016/
j.jorganchem.2018.07.006.
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ACCEPTED MANUSCRIPT
Syntheses, characterization and reactivity of dinuclear ruthenium-nickel
complexes with hexane-2,5-dione bis(thiosemicarbazonato) ligands
Duo-Wen Fang, Ai-Quan Jia*, 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 hexane-2,5-dione bis(thiosemicarbazones) ([CH3‒C{=N‒NH‒C(=S)‒NHR}‒CH2]2, R =
H, L1H2; CH3, L2H2‒Me; CH2CH3, L3H2‒Et; C6H5, L4H2‒Ph) with nickel(II) acetate hydrate in
refluxing ethanol gave a series of NiIIN2S2 metalloligands [Ni(L-R)] for the generation of hetero-
bimetallic complexes. The reaction of equal mole each of [Ni(L1)], [Ni(L2‒Me)], [Ni(L3‒Et)], or
[Ni(L4‒Ph)] with [RuCl2(dmso)4] (dmso = dimethyl sulfoxide) at reflux resulted in isolation of neutral
dinuclear ruthenium-nickel complexes [RuCl2{(Ni(L1)}(dmso)2] (1), [RuCl2{(Ni(L2‒Me)}(dmso)2] (2),
[RuCl2{(Ni(L3‒Et)}(dmso)2] (3), and [RuCl2{(Ni(L4‒Ph)}(dmso)2] (4). Interaction of [Ni(L-R)] with
[CpRu(PPh3)2Cl] (Cp‒ = cyclopentadienyl) at room temperature led to formation of cationic dinuclear
organoruthenium-nickel complexes [CpRu{(Ni(L1)}(PPh3)]Cl (5), [CpRu{(Ni-(L2‒Me)}(PPh3)]Cl (6),
[CpRu{(Ni(L3‒Et}(PPh3)]Cl (7), and [CpRu{(Ni(L4‒Ph}(PPh3)]Cl (8). New bimetallic ruthenium-
nickel complexes 1‒8 have been characterized spectroscopically, of which molecular structures of three
complexes [RuCl2{(Ni(L2‒Me)}(dmso)2]·CH2Cl2 (2·CH2Cl2), [CpRu-{(Ni(L2‒Me)}(PPh3)]Cl EtOH
(6 EtOH), and [CpRu{(Ni(L3‒Et}(PPh3)]Cl (7 H2O) have been established by single-crystal X-ray
crystallography. Their catalytic activities for the acetalation of benzaldehyde in the presence of
molecular H2 have been also investigated in this paper.
Keywords: {Ni(µ-S)2Ru}-type complex; Bis(thiosemicarbazones); Metalloligand; X-Ray crystal
structure; Catalytic activity
___________________
* Corresponding authors. E-mails: jaiquan@ahut.edu.cn (A.-Q. Jia) and zhangqf@ahut.edu.cn (Q.-F. Zhang).
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1. Introduction
Hydrogenases (H2ases) are a class of biological enzymes which catalyze the production and
consumption of molecular H2 [1]. According to the metal content in their active sites, H2ases are
generally classified as [NiFe]H2ases, [FeFe]H2ases, and [Fe]H2ases, of which [NiFe]H2ases are the
most popular and were firstly characterized by X-ray crystallography in 1995 [2]. Afterwards, the
synthetic chemists have paid much attention on the designs and syntheses of various sulfur-bridged
bimetallic [NiFe] complexes so that the catalytic mechanism of native [NiFe]H2ases could be well
understood [3‒7]. As known, the elements of ruthenium and iron are congeners, of which the
ruthenium atom may coordinate with both hard and soft ligands including dihydrogen or hydride. As a
result, the preparation of bimetallic NiRu complexes to simulate the core structures of [NiFe]H2ases
has attracted great attention. In 2007, Ogo reported a NiRu-based bis(
[(NiL)Ru(H2O)(η6-C6Me6)](NO3)2, which could catalyze the heterolytic cleavage of molecular H2,
successfully resulting in isolation of a hydrido bridged complex [(NiIIL)(H2O)( -H)RuII(η6
µ
-thiolato)NiIIRuII complex,
µ
-
C6Me6)](NO3), where L = N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)-1,3-propanediamine [8]. Moreover,
several other organoruthenium-nickel complexes, based on {NiS4}, {NiP2S2}, and {NiN2S2} moieties,
were synthesized in the following work and these complexes were shown to be capable of activation to
the molecular H2 [9‒11]. On the other hand, the thiosemicarbazones functionalized groups with
nitrogen and sulfur donor atoms may lead to various potent ligands by later modifications. These
ligands and their transition metal complexes have been widely studied during past decades mainly due
to their rich structure diversities and various biological properties [12, 13]. Thiosemicarbazones usually
bond to transition metal ions through the sulfur and hydrazine nitrogen atoms to form four- or five-
membered rings [14‒16]. When referred to limited hexane-2,5-dione bis(thiosemicarbazonato)
complexes, the stable 5:7:5-membered chelate ring systems accordingly formed [17‒19]. Rauchfuss
and Ogo have previously employed the nickel(II) metalloligands bearing flexible tetradentate N2S2
ligands, N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)-1,3-diaminoethane, 1,5-bis(2-mercapto-2-methyl-
propyl)-1,5-diazacyclooct-ane (bme*-daco), or N,N′-dimethyl-N,N′-bis(2-mercapto-ethyl)-1,3-propane-
diamine, to construct bimetallic NiRu complexes [8, 20]. We have recently reported two
organoruthenium-nickel complexes with a rigid tetradentate N2S2 ligand, N,N’-bis(2-thiobenzylidene)-
1,2-phenylenediaminato, as shown in Chart 1 [21]. Herein, we describe the employment of a series of
versatile and adjustable {NiN2S2} metalloligands [Ni(L-R)] (L-R = hexane-2,5-dione bis(thiosemi-
carbazonato)) to construct dinuclear ruthenium-nickel complexes. The reactivity of the structurally
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defined complexes towards molecular H2 was initially investigated in this paper.
2. Experimental
2.1. General
All synthetic manipulations were carried out under dry dinitrogen atmosphere by standard
Schlenk techniques. Solvents were purified, distilled and degassed prior to use. Published procedures
were followed in the preparation of [Ni(L-R)] (L-R = hexane-2,5-dione bis(thiosemicarbazonato)) [17,
18], cis-[RuCl2(dmso)4] (dmso = dimethyl sulfoxide) [22], and [CpRu(PPh3)2Cl] (Cp‒
=
cyclopentadienyl) [23]. NMR spectra were recorded on a Bruker ALX 400 spectrometer operating at
31
400 and 162 MHz for 1H and P, respectively. Chemical shifts (
δ
, ppm) were reported with reference
to SiMe4 (1H) and 85% H3PO4 (31P). 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.
2.2. Preparation of [RuCl2{Ni(L1)}(dmso)2] (1)
To a solution of [RuCl2(dmso)4] (48.5 mg, 0.10 mmol) in N,N-dimethyl formamide (DMF, 5 mL)
was added a solution of [Ni(L1)] (31.7 mg, 0.10 mmol) in DMF (5 mL), and then the mixture was
stirred at reflux overnight, the resulting black solution was concentrated to ca. 3 mL. Slow addition of
diethyl ether gave a black precipitate, which was filtered, washed by diethyl ether (3 × 5 mL) and
hexane (3 × 5 mL), and dried under vacuum. Yield: 60 mg, 75% (based on Ru). IR (KBr disc, cm-1):
vNH2 3454 (m); vC=N 1640 (m), 1608 (m); vS=O 1084 (s); vC‒S 805 (m). 1H NMR (400 MHz, DMSO-d6):
δ 8.78 (s, 2H, -NH2), 8.70 (s, 2H, -NH2), 3.60 (s, 3H, -CH3S), 3.55 (s, 3H, -CH3S), 3.48 (s, 3H, -CH3S),
3.44 (s, 3H, -CH3S), 3.35 (m, 2H, -CH2), 2.84 (m, 2H, -CH2), 1.95 (s, 3H, -CH3), 1.89 (s, 3H, -CH3)
ppm. 13C NMR (100 MHz, DMSO-d6): 28.91 (CH3), 29.23 (CH3), 31.31 (CH2), 31.35 (CH2), 42.81
(SCH3), 43.55 (SCH3), 43.60 (SCH3), 45.71 (SCH3), 164.52 (C=N-N), 165.52 (C=N-N), 170.51 (N=C-
S), 171.35 (N=C-S) ppm. FAB-MS (MeCN): m/z 574.4 [Ru{Ni(L1)}(dmso)2]+, 496.2
[Ru{Ni(L1)}(dmso)]+, 418.1 [Ru{Ni(L1)}]+. Anal. Calcd. for C12H26Cl2N6O2S4NiRu: C, 22.34; H, 4.06;
N, 13.02%. Found: C, 22.39; H, 4.04; N, 13.07%.
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2.3. Preparation of [RuCl2{Ni(L2-Me)}(dmso)2]·CH2Cl2 (2·CH2Cl2)
To a solution of [RuCl2(dmso)4] (48.5 mg, 0.10 mmol) in tetrahydrofuran (THF, 5 mL) was added
a solution of [Ni(L2-Me)] (34.5 mg, 0.10 mmol) in THF (10 mL), and then the mixture was stirred at
reflux overnight, the resulting purple solution was concentrated to ca. 3 mL. Slow addition of diethyl
ether gave a purple precipitate, which was filtered and washed by diethyl ether (3 × 5 mL) and hexane
(3 × 5 mL). The product was then recrystallized from dichloromethane/diethyl ether to give black
flake-shape crystals. Yield: 65 mg, 80% (based on Ru). IR (KBr disc, cm-1): vNH 3254 (m); vC=N 1623
(m), 1600 (m); vS=O 1087 (s); vC‒S 800 (m). 1H NMR (400 MHz, CDCl3): δ 7.46 (s, 1H, -NH), 6.39 (s,
1H, -NH), 3.57 (s, 3H, -CH3S), 3.53 (s, 3H, -CH3S), 3.42(m, 2H, -CH2), 3.31 (s, 3H, -CH3S), 3.04 (s,
3H, -CH3S), 2.83 (d, J = 3.6 Hz, 6H, -NHCH3), 2.43 (m, 2H, -CH2), 2.07 (s, 3H, -CH3), 2.04 (s, 3H, -
13
CH3) ppm. C NMR (100 MHz, CDCl3): 20.96 (CH3), 21.42 (CH3), 31.39 (CH2), 31.49 (CH2), 31.62
(NCH3), 31.99 (NCH3), 45.10 (SCH3), 45.13 (SCH3), 45.16 (SCH3), 47.17 (SCH3), 162.76 (C=N-N),
163.97 (C=N-N), 168.26 (N=C-S), 169.07 (N=C-S) ppm. FAB-MS (MeCN): m/z 602.4 [Ru{Ni(L2-
Me)}(dmso)2]+, 524.3 [Ru{Ni(L2-Me)}(dmso)]+, 446.2 [Ru{Ni(L2-Me)}]+. Anal. Calcd. for
C14H30Cl2N6O2S4NiRu (CH2Cl2): C, 23.81; H, 4.27; N, 11.12%. Found: C, 23.85; H, 4.24; N, 11.22%.
2.4. Preparation of [RuCl2{Ni(L3-Et)}(dmso)2] (3)
To a solution of [RuCl2(dmso)4] (48.5 mg, 0.10 mmol) in THF (5 mL) was added a solution of
[Ni(L3-Et)] (37.3 mg, 0.10 mmol) in THF (10 mL), and then the mixture was stirred at reflux overnight,
the resulting purple solution was concentrated to ca. 3 mL. Slow addition of diethyl ether gave a purple
precipitate, which was filtered, washed by diethyl ether (3 × 5 mL) and hexane (3 × 5 mL), and dried
under vacuum. The product was then recrystallized from tetrahydrofuran/diethyl ether to give purple
needle-shape crystals. Yield: 60 mg, 70% (based on Ru). IR (KBr disc, cm-1): vNH 3228 (m); vC=N 1621
(m), 1609 (m); vS=O 1089 (s); vC‒S 795 (m). 1H NMR (400 MHz, DMSO-d6): δ 7.45 (s, 1H, -NH), 6.75
(s, 1H, -NH), 3.57 (s, 3H, -CH3S), 3.53 (s, 3H, -CH3S), 3.31 (s, 3H, -CH3S), 3.05 (s, 3H, -CH3S), 2.93
(m, 4H, -NHCH2CH3), 2.42 (m, 4H, -CH2), 1.98 (s, 3H, -CH3), 1.88 (s, 3H, -CH3), 0.95 (t, J = 7.2 Hz,
6H, -CH2CH3) ppm. 13C NMR (100 MHz, DMSO-d6): 20.61 (CH2CH3), 20.98 (CH2CH3), 29.06 (CH3),
29.18 (CH3), 31.32 (CH2), 31.39 (CH2), 40.71 (NCH2CH3), 40.76 (NCH2CH3), 43.81 (SCH3), 43.86
(SCH3), 43.90 (SCH3), 45.87 (SCH3), 162.01 (C=N-N), 163.06 (C=N-N), 168.83 (N=C-S), 169.85
(N=C-S) ppm. FAB-MS (MeCN): m/z 630.5 [Ru{Ni(L3-Et)}(dmso)2]+, 552.4 [Ru{Ni(L3-Et)}(dmso)]+,
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474.2 [Ru{Ni(L3-Et)}]+. Anal. Calcd. for C16H34Cl2N6O2S4NiRu: C, 27.40; H, 4.89; N, 11.98%. Found:
C, 27.45; H, 4.85; N, 11.93%.
2.5. Preparation of [RuCl2{Ni(L4-Ph)}(dmso)2] (4)
To a solution of [RuCl2(dmso)4] (48.5 mg, 0.10 mmol) in DMF (5 mL) was added a solution of
[Ni(L4-Ph)] (46.9 mg, 0.10 mmol) in DMF (10 mL), and then the mixture was stirred at reflux
overnight, the resulting black solution was concentrated to ca. 3 mL. Slow addition of diethyl ether
gave a black precipitate, which was filtered and washed by diethyl ether (3 × 5 mL) and hexane (3 × 5
mL), and dried under vacuum. Yield: 45 mg, 50% (based on Ru). IR (KBr disc, cm-1): vNH 3217 (m);
vC=N 1625 (m), 1603 (m); vS=O 1088 (s); vC‒S 804 (m). 1H NMR (400 MHz, DMSO-d6): δ 8.28 (s, 1H, -
NH), 7.83 (s, 1H, -NH), 7.23-7.56 (m, 10H, -C6H5), 3.60 (s, 3H, -CH3S), 3.55 (s, 3H, -CH3S), 3.50 (s,
3H, -CH3S), 3.46 (s, 3H, -CH3S), 3.32 (m, 2H, -CH2), 2.83 (m, 2H, -CH2), 1.95 (s, 3H, -CH3), 1.89 (s,
3H, -CH3) ppm. 13C NMR (100 MHz, DMSO-d6): 20.52 (CH3), 20.59 (CH3), 34.31 (CH2), 34.36 (CH2),
36.03 (NCH3), 36.09 (NCH3), 43.05 (SCH3), 43.82 (SCH3), 45.52 (SCH3), 45.63 (SCH3), 119.51(Ar),
123.83 (Ar), 125.24 (Ar), 128.76 (Ar), 134.06 (Ar), 160.86 (C=N-N), 161.46 (C=N-N), 169.65 (N=C-
S), 170.06 (N=C-S) ppm. FAB-MS (MeCN): m/z 726.6 [Ru{Ni(L4-Ph)}(dmso)2]+, 648.4 [Ru{Ni(L4-
Ph)}(dmso)]+, 570.3 [Ru{Ni(L4-Ph)}]+. Anal. Calcd. for C24H34Cl2N6O2S4NiRu: C, 36.18; H, 4.31; N,
10.56%. Found: C, 36.14; H, 4.27; N, 10.62%.
2.6. Preparation of [CpRu{Ni(L1)}(PPh3)]Cl (5)
To a solution of [CpRu(PPh3)2Cl] (72.6 mg, 0.10 mmol) in THF (5 mL) was added a solution of
[Ni(L1)] (31.7 mg, 0.10 mmol) in THF (10 mL), and then the mixture was stirred at room temperature
overnight, the resulting dark-green solution was concentrated to ca. 3 mL. Slow addition of diethyl
ether gave a dark-green precipitate, which was filtered, washed by diethyl ether (3 × 5 mL) and hexane
(3 × 5 mL), and dried under vacuum. Yield: 68 mg, 69% (based on Ru). IR (KBr disc, cm-1): vNH2 3436
(m); vC=N 1613 (m), 1609 (m); vC‒P 1091 (m); vC‒S 791 (m). 31P NMR (162 MHz, DMSO-d6): δ 54.0
1
ppm. H NMR (400 MHz, DMSO-d6): δ 7.90 (s, 2H, -NH2), 6.72 (s, 2H, -NH2), 7.15-7.43 (m, 15H, -
13
PPh3), 4.32 (s, 5H, -Cp), 2.08 (m, 4H, -CH2), 2.01 (s, 3H, -CH3), 1.83 (s, 3H, -CH3). C NMR (100
MHz, DMSO-d6): 22.24 (CH3), 22.28 (CH3), 34.34 (CH2), 34.39 (CH2), 77.23 (Cp), 128.42 (Ar),
133.45 (Ar), 137.86 (Ar), 138.83 (Ar), 162.54 (C=N-N), 163.14 (C=N-N), 169.74 (N=C-S), 170.54
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(N=C-S) ppm. FAB-MS (MeCN): m/z 745.0 [CpRu{Ni(L1}(PPh3)]+, 483.0 [CpRu{Ni(L1)}]+. Anal.
Calcd. for C31H34ClN6PS2NiRu: C, 47.68; H, 4.39; N, 10.76%. Found: C, 47.62; H, 4.35; N, 10.79%.
2.7. Preparation of [CpRu{Ni(L2-Me)}(PPh3)]Cl EtOH (6 EtOH)
To a solution of [CpRu(PPh3)2Cl] (72.6 mg, 0.10 mmol) in THF (5 mL) was added a solution of
[Ni(L2-Me)] (34.5 mg, 0.10 mmol) in THF (10 mL), and then the mixture was stirred at room
temperature overnight, the resulting dark green solution was concentrated to ca. 3 mL. Slow addition of
diethyl ether gave a green precipitate, which was filtered and washed by diethyl ether (3 × 5 mL) and
hexane (3 × 5 mL). The product was then recrystallized from ethanol to give black block-shape crystals.
Yield: 75 mg, 73% (based on Ru). IR (KBr disc, cm-1): vNH 3294 (m); vC=N 1603 (m), 1590 (m); vC‒P
1085 (m); vC‒S 802 (m). 31P NMR (162 MHz, DMSO-d6): δ 54.0 ppm. 1H NMR (400 MHz, DMSO-d6):
δ 8.06 (s, 1H, -NH), 7.74 (s, 1H, -NH), 7.19-7.44 (m, 15H, -PPh3), 4.30 (s, 5H, -Cp), 3.28 (m, 2H, -
CH2), 2.98 (s, 6H, -NCH3), 2.88 (m, 2H, -CH2), 2.00 (s, 3H, -CH3), 1.81 (s, 3H, -CH3). 13C NMR (100
MHz, DMSO-d6): 21.03 (CH3), 21.09 (CH3), 34.23 (CH2), 34.28 (CH2), 35.76 (NCH3), 35.84 (NCH3),
77.43 (Cp), 128.55 (Ar), 134.25 (Ar), 138.37 (Ar), 139.53 (Ar), 163.33 (C=N-N), 164.23 (C=N-N),
170.69 (N=C-S), 171.45 (N=C-S) ppm. FAB-MS (MeCN): m/z 773.1 [CpRu{Ni(L2-Me)}(PPh3)]+,
511.0 [CpRu{Ni(L2-Me)}]+. Anal. Calcd. for C33H38ClN6PS2NiRu (C2H6O): C, 49.18; H, 4.24; N,
11.22%. Found: C, 49.22; H, 4.22; N, 11.25%.
2.8. Preparation of [CpRu{Ni(L3-Et)}(PPh3)]Cl H2O (7 H2O)
To a solution of [CpRu(PPh3)2Cl] (72.6 mg, 0.10 mmol) in THF (5 mL) was added a solution of
[Ni(L3-Et)] (37.3 mg, 0.10 mmol) in THF (10 mL), and then the mixture was stirred at room
temperature overnight, the resulting dark green solution was concentrated to ca. 3 mL. Slow addition of
diethyl ether gave a green precipitate, which was filtered and washed by diethyl ether (3 × 5 mL) and
hexane (3 × 5 mL). The product was then recrystallized from ethanol to give black block-shape crystals.
Yield: 64 mg, 70% (based on Ru). IR (KBr disc, cm-1): vNH 3286 (m); vC=N 1604 (w), 1596 (m); vC‒P
1086 (m); vC‒S 802 (m). 31P NMR (162 MHz, DMSO-d6): δ 54.4 ppm. 1H NMR (400 MHz, DMSO-d6):
δ 7.96 (s, 1H, -NH), 7.70 (s, 1H, -NH), 7.10-7.45 (m, 15H, -PPh3), 4.31 (s, 5H, -Cp), 3.40 (m, 2H, -
CH2), 3.06 (m, 4H, -CH2NH), 2.88 (m, 2H, -CH2), 1.99 (s, 3H, -CH3), 1.91 (s, 3H, -CH3), 0.94 (t, J =
7.2 Hz, 6H, -CH2CH3). 13C NMR (100 MHz, DMSO-d6): 15.56 (NCH2CH3), 15.62 (NCH2CH3), 29.01
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(CH3), 29.07 (CH3), 34.18 (CH2), 34.23 (CH2), 41.06 (NCH2CH3), 41.12 (NCH2CH3), 77.64 (Cp),
128.75 (Ar), 134.05 (Ar), 137.95 (Ar), 139.27 (Ar), 161.12 (C=N-N), 161.23 (C=N-N), 170.15 (N=C-
S), 171.00 (N=C-S) ppm. FAB-MS (MeCN): m/z 801.1 [CpRu{Ni(L3-Et)(PPh3)]+, 539.0 [CpRu{Ni(L3-
Et)}]+. Anal. Calcd. for C35H42ClN6PS2NiRu: C, 50.23; H, 5.06; N, 10.05%. Found: C, 50.19; H, 5.03;
N, 10.09%.
2.9. Preparation of [CpRu{Ni(L4-Ph)}(PPh3)]Cl (8)
To a solution of [CpRu(PPh3)2Cl] (72.6 mg, 0.10 mmol) in THF(5 mL) was added a solution of
[Ni(L4-Ph)] (46.9 mg, 0.10 mmol) in THF (10 mL), and then the mixture was stirred at room
temperature overnight, the resulting dark-green solution was concentrated to ca. 3 mL. Slow addition of
diethyl ether gave a dark-green precipitate, which was filtered, washed by diethyl ether (3 × 5 mL) and
hexane (3 × 5 mL), and dried under vacuum. Yield: 73 mg, 61% (based on Ru). IR (KBr disc, cm-1):
vNH 3233 (m); vC=N 1621 (m), 1611 (m); vC‒P 1082 (m); vC‒S 798 (m). 31P NMR (162 MHz, DMSO-d6):
1
δ 54.7 ppm. H NMR (400 MHz, DMSO-d6): δ 8.00 (s, 1H, -NH), 7.72 (s, 1H, -NH), 7.10-7.46 (m,
15H, -PPh3, -C6H5), 4.35 (s, 5H, -Cp), 3.32 (m, 2H, -CH2), 2.81 (m, 2H, -CH2), 1.90 (s, 3H, -CH3),
13
1.81 (s, 3H, -CH3). C NMR (100 MHz, DMSO-d6): 22.71 (CH3), 22.716 (CH3), 33.68 (CH2), 33.75
(CH2), 76.94 (Cp), 119.53 (Ar), 123.84 (Ar), 128.75 (Ar), 134.05 (Ar), 137.94 (Ar), 138.04 (Ar),
139.24 (Ar), 163.86 (C=N-N), 164.56 (C=N-N), 172.42 (N=C-S), 173.12 (N=C-S) ppm. FAB-MS
(MeCN): m/z 897.1 [CpRu{Ni(L4-Ph)}(PPh3)]+, 635.0 [CpRu{Ni(L4-Ph)}]+. Anal. Calcd. for
C43H42ClN6PS2NiRu: C, 55.36; H, 4.54; N, 9.01%. Found: C, 55.32; H, 4.51; N, 9.05%.
2.10. X-Ray crystallography
A summary of crystallographic data and experimental details for complexes 2·CH2Cl2, 6 EtOH,
and 7 H2O are listed in Table 1. Intensity data were collected on a Bruker SMART APEX 2000 CCD
diffractometer using graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å) at 293(2) K. The data
was corrected for absorption using the program SADABS [24]. Structures were solved by the direct
methods and refined by full-matrix least-squares on F2 using the SHELXTL software package [25, 26].
All non-hydrogen atoms were refined anisotropically. Hydrogen atoms in the phenyl and other organic
moieties were treated as idealized contributions (Csp3−H = 0.96, Csp2−H = 0.93 Å, and N−H =
7

ACCEPTED MANUSCRIPT
0.86−0.93 Å). The ethanol solvent molecule in 6 EtOH and water molecule in 7 H2O was refined
without hydrogen atoms.
2.11. Typical procedure for acetalation of benzaldehyde with ethanol in the presence of NiRu
complexes and H2
The catalyst solution was prepared by dissolving complex 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
Treatment of the metalloligands [Ni(L-R)] with cis-[RuCl2(dmso)4] in DMF or THF at reflux
afforded neutral “Ni(µ-S)2Ru” bimetallic complexes of the type [RuCl2{Ni(L-R)}(dmso)2] (1‒4), two
dmso ligands in cis-[RuCl2(dmso)4] were replaced by the [Ni(L-R)] units. Reactions of
[CpRu(PPh3)2Cl] and the metalloligands [Ni(L-R)] in THF at room temperature led to isolation of the
expected cationic “Ni(µ-S)2Ru” complexes [CpRu{Ni(L-R)}(PPh3)]Cl (5‒8) in moderate to good
yields. One triphenylphosphine and one chloro ligands in [CpRu(PPh3)2Cl] were substituted by the
[Ni(L-R)] units and the left chloro ligand acted as the counter anion in the formation of complexes 5‒8
(Scheme 1), which may be monitored by in situ 31P NMR spectroscopy, showing known signals of the
free PPh3 (δ = −6.65 ppm) and the oxidized OPPh3 (δ = 22.8 ppm) along with a new signal (δ = 54.0
ppm) of the final product. Complexes 1‒4 are air-stable in the solid state but easily oxygenates when
exposed to air in solution for a couple of hours, whereas complexes 5‒8 are relatively air-stable both in
solution and in the solid state, possibly due to the presence of strong σ-donor triphenylphosphine ligand.
The IR spectra of complexes 1‒8 clearly show two intense bands of vC=N at around 1600 and
1590 cm−1, one medium band of vN‒H in the region 3500‒3200 cm−1, and the band at about 800 cm−1
due to the vC‒S mode, indicating the thiol form of L-R ligands (Chart 2) [19, 27, 28]. The presence of
PPh3 in complexes 5–8 is confirmed by the observation of a characteristic νP‒C band in the range 1082–
8

ACCEPTED MANUSCRIPT
1091 cm−1. In addition, the vS=O band, observed at approximately 1090 cm−1 in complexes 1–4,
confirms the presence of sulfur-bonded dmso in the ruthenium coordination sphere [29]. The 1H NMR
spectra of complexes 1‒4 all show a singlet for the CH3S group protons at around 3.5 ppm. The Cp
group in complexes 5–8 exhibited as a singlet at about 4.3 ppm, which is compared with that in related
31
ruthenium complexes [30]. The P NMR spectra of complexes 5‒8 displayed PPh3 signals at around
54.0 ppm, similar to that in the related complex [CpRu(PPh3)S2CNSiiPr3(1-Naphth)] (53.7 ppm) [30].
The 13C NMR spectra of complexes 1‒8 showed peaks at around 170 and 165 ppm for the N=C‒S and
C=N‒N moieties, respectively. The positive ion FAB mass spectra of 1‒8 showed the expected peaks
which corresponded to the cation ions [Ru{Ni(L-R)}(dmso)2]+ or [CpRu{Ni(L-R)}(PPh3)]+, and
[Ru{Ni(L-R)}(dmso)]+ or [CpRu{Ni(L-R)}]+ with the characteristic isotopic distribution patterns.
The molecular structures of complexes 2·CH2Cl2, 6 EtOH, and 7 H2O have been established by
single-crystal X-ray crystallography. Complex 2·CH2Cl2 crystallizes in monoclinic P21/c space group,
while complexes 6 EtOH and 7 H2O both crystallize in monoclinic P21/n space group. The structures of
[RuCl2{Ni(L2-Me)}(dmso)2] in 2·CH2Cl2 and cationic parts [CpRu{Ni(L-R)}(PPh3)] in 6 EtOH and
7 H2O are depicted in Figs. 1‒3, respectively. Selected bond lengths and bond angles for complexes
2·CH2Cl2, 6 EtOH, and 7 H2O and some related complexes are summarized in Table 2 for comparison.
The C‒S bond lengths ranging from 1.781(3) to 1.798(3) Å, together with the (S)C=N bond lengths
ranging from 1.285(4) to 1.307(4) Å for thiosemicarbazonato fragments in complexes 2·CH2Cl2,
6 EtOH, and 7 H2O, further imply their binegative thiol form of L-R ligands [17, 18, 31]. The
structures of {Ni(L-R)} unit in complexes 2·CH2Cl2, 6 EtOH, and 7 H2O all have 5:7:5-membered
chelate ring systems. The coordination around the nickel atoms involve a distortion from the square
planarity and the ruthenium atoms all adopt a distorted-octahedral coordination in complexes 2·CH2Cl2,
6 EtOH, and 7 H2O. For complex 2·CH2Cl2, the ruthenium atom is surrounded by two sulfur atoms
from the metalloligand [Ni(L2-Me)], two cis chloro and two sulfur atoms from two cis S-bonded dmso
ligands. For complexes 6 EtOH and 7 H2O, the ruthenium atoms are surrounded by one Cp ring, one
triphenylphosphine ligand and the metalloligand [Ni(L-R)]. The Ru−Sdmso bond lengths of 2.2485(8)
and 2.2679(8) Å, Ru−Cl bond lengths of 2.4201(9) and 2.4459(9) Å, as well as the Cl−Ru−Cl bond
angle of 89.19(3)o in complex 2·CH2Cl2, agree well with those in other similar complex
[RuCl2(dmso)2(MeS(CH2)2SMe)] (2.2676(8), 2.3104(9) Å; 2.4193(9), 2.4438(9) Å; 89.81(4)o) [32].
The average Ru−C bond length is 2.179(3) Å in complex 7 H2O, similar to that of 2.179(2) Å in
complex 6 EtOH.
9

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Complexes 2·CH2Cl2, 6 EtOH, and 7 H2O all contain a NiS2Ru butterfly core, in which the nickel
and ruthenium atoms are located in wing, joined by a pair of bidentate thiolato ligands as the body of
the butterfly. The dihedral angles of two NiS2 and RuS2 trianglar planes are 50.24(4)o for complex
2·CH2Cl2, 50.13(3)o for complex 6 EtOH, and 49.01(2)o for complex 7 H2O, which are much smaller
than that of 74.35(6)o in complex [CpRu{Ni(tsalphen)}(PPh3)]+ (tsalphen = N,N’-bis(2-
thiobenzylidene)-1,2-phenylenediaminato) [21], suggesting the {NiN2S2} unit is obviously crucial for
the butterfly structure. The Ni Ru distances in complexes 2·CH2Cl2, 6 EtOH, and 7 H2O are similar,
being 3.173 Å for complex 2·CH2Cl2, 3.116 Å for complex 6 EtOH, and 3.139 Å for complex 7 H2O,
which lie in the range of 2.877‒3.352 Å in other reported bimetallic [Ni(µ-S)Ru] complexes [20, 33,
34], though obviously longer than that in the hydrido-bridged Ni(µ-H)(µ-S)2Ru complex
[(NiIIL)(H2O)(µ-H)RuII(η6-C6Me6)](NO3) (L = N,N′-dimethyl-N,N′-bis(2-mercaptoethyl)-1,3-propane-
diamine) (2.739(3) Å) [8]. The bond angle of N(2)−Ni(1)−S(1) (168.10(8)°) is almost the same to
N(1)−Ni(1)−S(2) (168.38(8)°) in the somewhat symmetrical complex 2·CH2Cl2. However, in cationic
complexes 6 EtOH and 7 H2O, the N(2)−Ni(1)−S(1) bond angles (173.05(8)° for 6 EtOH and
172.64(6)° for 7 H2O) are obviously larger than those of N(1)−Ni(1)−S(2) bond angles (164.79(8)o for
6 EtOH and 165.07(6)o for 7 H2O). The Ni−S−Ru angles of 87.15(3) and 87.98(3)°in 2·CH2Cl2 are a
little larger than those of 84.22(3) and 85.95(3)° in 6 EtOH, as well as 84.97(2) and 86.65(2)° in 7 H2O,
a suggestive of the ruthenium surroundings also having influence on the core structure of {Ni(µ-S)2Ru}.
The S−Ru−S bond angle of 77.83(3)° in 6 EtOH is similar to that in 7 H2O (77.48(2)°), indicating the
alkyl substituent on thiosemicarbazonato ligands have little effect on the bond parameters.
As stated above, Ogo and coworkers have reported that complex [(NiIIL)(H2O)RuII(
could catalyze the heterolytic cleavage of hydrogen molecules and followed isolation of a hydrido
bridged species [8]. Moreover, complex [(
[(NiIIL)(H2O)(µ-H)RuII( 6-C6Me6)]+ 6-p-
η
6-C6Me6)]2+
η
η
cymene)Ru{Ni(tsalphen)}(MeCN)](OTf)2 was found to catalyze acetalation of benzaldehyde with
ethanol in the presence of H2 [21]. Complex 2 was thus tested in such reactions and benzaldehyde
diethyl acetal [C6H5CH(OCH2CH3)2] was also observed from GC-MS analysis (Fig. 4), suggesting that
acetalation of benzaldehyde took place in the presence of complex 2 and H2. Controlled reaction
without participation of H2 did not give the acetal product, presenting H2 being the source of H+, a
prerequisite for the acetalation reaction. The pH measurements were performed on the reaction process,
which showed that the pH of the solution decreased (from pH 6.4 to pH 5.1), indicating the heterolytic
10

ACCEPTED MANUSCRIPT
H2 cleavage [8, 35]. Based on Ogo’s work [8], the possible mechanism of the acetalization of PhCHO
is proposed as following: (1) One of the labile dmso ligands on ruthenium center in complex 2 left and
a coordinately unsaturated species {RuCl2{Ni(L2-Me)}(dmso)} formed. (2) Heterocleavage of H2
produced the hydrido-bridged species {RuCl2{Ni(L2-Me)}(dmso)(µ-H)} along with the active protons.
(3) The resulted protons catalyzed the typical acetalation of benzaldehyde and ehanol. The effect of
temperature, reaction time and the amount of catalyst on acetalation reaction were investigated in detail
o
o
(see Table 3). When the temperature increased from 0 C to 60 C, the conversion of benzaldehyde
increased from 2.4% to 15.5%, suggesting that the relatively higher temperature benefits the reaction.
o
Although the higher temperatures did not lead to obvious increase after 40 C, as a matter of the fact,
the reactions might be done at 40 oC for the following attempts. Longer reaction time also led to a little
increase of conversion (entries 5 to 10). As expected, the conversion increased with the increased
amount of bimetallic {Ni(µ-S)2Ru} complex 2 (entries 11 and 12). The substituent of methyl, ethyl, or
phenyl seemed to have little effect on the catalytic activity (entries 11 and 13−15). When complexes
5‒8 were used to initiate the reaction, the compound benzaldehyde diethyl acetal was also observed.
Therefore, the conversions in this catalytic system may be compared with that in other transition metal
catalyzed ethanolysis of benzaldehyde [36].
In summary, although bis(thiosemicarbazonato)nickel(II) complexes with tetradentate tricyclic-
ligand systems were reported as early as 1970 by McCleverty [31], these mononuclear nickel(II)
complexes have not been employed to further construct heterobimetallic complexes according to a
CCDC search. Syntheses and characterization of a series of thiolate-bridged bimetallic nickel-
ruthenium complexes based on hexane-2,5-dione bis(thiosemicarbazonato)-nickel(II) units were
reported in this paper. X-Ray diffraction studies may establish the thiol form of thiosemicarbazonato
moieties due to the characteristic C‒S bond lengths ranging from 1.781(3) to 1.797(2) Å in complexes
2·CH2Cl2, 6 EtOH, and 7 H2O. The Ni Ru distances in complexes 2·CH2Cl2, 6 EtOH, and 7 H2O are
3.173, 3.116, and 3.139 Å, respectively, which agree well with those in other related bimetallic nickel-
ruthenium complexes with [NiN2S2] metalloligands [20, 21, 33, 34]. The triphenylphosphine ligands
may stabilize the {Ni(µ-S)2Ru} complexes 6 EtOH and 7 H2O, indicated by their slightly shorter
Ni Ru distances. Complexes 1‒8 could effectively catalyze acetalation of benzaldehyde with ethanol
in the presence of 1 atm molecular H2.
4. Supplementary material
11

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Crystallographic data for [RuCl2{Ni(L2-Me)}(dmso)2]·CH2Cl2 (2), [CpRu{Ni(L2-
Me)}(PPh3)]Cl EtOH (6), and [CpRu{Ni(L3-Et)}(PPh3)]Cl H2O (7 H2O) have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publication nos. CCDC 1840252, 1840253,
and 1840254, 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 Foundation of China (grant no. 21372007).
We thank the reviewers’ helpful suggestion during the revision of this paper.
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Table 1.
Crystallographic data and experimental details for [RuCl2{Ni(L-Me)}(dmso)2]·CH2Cl2 (2·CH2Cl2),
[CpRu{Ni(L-Me)}(PPh3)]Cl EtOH (6 EtOH) and [CpRu{Ni(L-Et)}(PPh3)]Cl (7 H2O).
,
complex
2·CH2Cl2
6 EtOH
C35H38ClN6OPS2NiRu
849.03
7·H2O
empirical formula
formula weight
crystal system
a (Å)
C15H32Cl4N6O2S4NiRu
758.28
C35H44ClN6OPS2NiRu
855.08
monoclinic
10.710(3)
32.865(8)
8.2559(19)
90
monoclinic
13.7443(11)
19.4666(16)
14.0206(11)
90
monoclinic
13.972(2)
19.742(2)
14.218(2)
90
b (Å)
c (Å)
α
β
γ
(°)
(°)
(°)
102.711(3)
90
95.9420(10)
90
97.456(1)
90
V (Å3)
2834.8(11)
P21/c
3731.1(5)
P21/n
3888.9(8)
P21/n
space group
Z
4
4
4
Dcalc (g cm-3)
temperature (K)
F(000)
1.777
1.511
1.460
296(2)
296(2)
296(2)
1536
1736
1760
µ
(Mo-K
α
) (mm-1)
1.894
1.173
1.125
total refln
17401
22988
23910
independent refln
parameters
Rint
6502
8532
8951
314
427
437
0.0284
0.0350
0.0208
R1a, wR2b (I > 2
σ
(I))
0.0339, 0.0717
0.0430, 0.0760
1.017
0.0341, 0.0908
0.0521, 0.1075
0.820
0.0286, 0.0754
0.0379, 0.0819
0.950
R1, wR2 (all data)
GoFc
a R1 = Fo– Fc /Fo.
2
2
b wR2 = [w(Fo  – Fc2)2/wFo 2]1/2
.
c GoF = [w(Fo – Fc)2/(Nobs – Nparam)]1/2.
15

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Table 2.
Comparison of selected bond lengths (Å) and angles (deg) for complexes 2·CH2Cl2, 6 EtOH and 7·H2O, and
some related nickel complexes.
2·CH2Cl2
1.792(3)
1.781(3)
1.285(4)
1.287(4)
1.341(4)
1.344(4)
1.282(4)
1.293(4)
1.412(4)
1.425(4)
2.1657(9)
2.1642(10)
1.913(2)
1.960(3)
2.4285(8)
2.3973(9)
85.62(3)
102.08(11)
75.14(3)
3.173
6 EtOH
7·H2O
Ni(L-H)
1.7434(14)
1.7374(15)
1.3051(17)
1.2887(18)
1.3392(19)
1.3619(18)
1.2816(18)
1.2923(17)
1.4202(17)
1.4181(15)
2.1542(4)
2.1718(4)
1.9155(11)
1.9751(12)
-
Ni(L-Ph)
1.721(5)
1.776(4)
1.290(5)
1.293(6)
1.357(5)
1.368(1)
1.296(5)
1.294(6)
1.413(5)
1.429(5)
2.147(1)
2.163(1)
1.903(3)
1.937(4)
-
C
‒
S
1.791(3)
1.798(3)
1.288(4)
1.307(4)
1.333(4)
1.343(4)
1.301(4)
1.286(4)
1.418(4)
1.411(3)
2.1801(8)
2.1656(8)
1.952(2)
1.896(2)
2.4570(8)
2.3990(7)
89.17(3)
99.46(10)
77.83(3)
3.116
1.789(2)
1.797(2)
1.294(3)
1.303(3)
1.331(3)
1.341(3)
1.294(3)
1.284(3)
1.414(3)
1.413(3)
2.1813(6)
2.1632(6)
1.9554(19)
1.9008(18)
2.4570(6)
2.4047(6)
88.91(2)
99.81(8)
77.48(2)
3.139
(S)C=N
C‒NHR
(Me)C=N
N‒N
Ni
Ni
‒
S
‒
N
Ru
Ru
‒S(1)
‒S(2)
-
-
S
‒
Ni
Ni
Ru
‒
S
88.755(14)
101.11(5)
-
87.8(1)
130.4(4)
-
N
‒
‒
N
S
‒
‒
S
Ru···Ni
-
-
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Table 3.
Acetalizationa of benzaldehyde with ethanol in the presence of Ni-Ru complexes and H2.
entry
1
catalyst
temperature/°C
time/h
conversion/%
2.4
0
4
4
4
4
1
2
3
4
5
10
4
4
4
4
4
4
4
4
4
2
2
2
15
40
60
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
7.8
3
13.2
15.5
4.4
2
4
2
5
2
6
8.5
2
7
10.3
13.2
15.2
16.3
33.7
37.0
32.0
33.6
33.1
24.2
25.6
26.0
25.3
2
8
2
9
2
10
11
12
13
14
15
16
17
18
19
2
2b
2c
1b
3b
4b
5b
6b
7b
8b
a Reactions were monitored by TLC/GC.
b The amount of catalyst is 0.001 mmol (twice of that in entry 3).
c The amount of catalyst is 0.025 mmol (five times of that in entry 3).
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Chart 1. The structures of four kinds of [NiN2S2] metalloligands in NiRu complexes.
Chart 2. The thione and thiolene forms of hexane-2,5-dione bis(thiosemicarbazones).
Scheme 1. Synthesis of heterobimetallic ruthenium-nickel complexes 1‒8.
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Fig. 1. Molecular structure of the cation of [RuCl2{Ni(L2-Me)}(dmso)2]·CH2Cl2 (2·CH2Cl2), with
thermal ellipsoids drawn at the 40% probability level. Solvent molecule is omitted for clarity.
Selected bonds (Å) and angles (°): Ru(1)‒S(1) 2.4285(8), Ru(1)‒S(2) 2.3973(9), Ru(1)‒S(3)
2.2485(8), Ru(1)‒S(4) 2.2679(8), Ru(1)‒Cl(1) 2.4201(9), Ru(1)‒Cl(2) 2.4459(9), Ru(1)···Ni(1)
3.173, Ni(1)‒N(1) 1.913(2), Ni(1)‒N(2) 1.960(3), Ni(1)‒S(1) 2.1657(9), Ni(1)‒S(2) 2.1642(10),
C(6)‒S(1) 1.792(3), C(7)‒S(2) 1.781(3), C(6)‒N(3) 1.285(4), C(7)‒N(4) 1.287(4), C(6)‒N(5)
1.341(4), C(7)‒N(6) 1.344(4), C(10)‒N(1) 1.282(4), C(13)‒N(2) 1.293(4), N(1)‒N(3) 1.412(4),
N(2)‒N(4) 1.425(4); S(2)‒Ru(1)‒S(1) 75.14(3), S(2)‒Ru(1)‒Cl(1) 170.81(3), S(1)‒Ru(1)‒S(4)
173.59(3), S(3)‒Ru(1)‒Cl(2) 175.77(3), N(2)‒Ni(1)‒N(1) 102.08(11), S(1)‒Ni(1)‒S(2) 85.62(3),
N(1)‒Ni(1)‒S(1) 83.72(8), N(2)‒Ni(1)‒S(2) 87.61(8), Ni(1)‒S(1)‒Ru(1) 87.15(3), Ni(1)‒S(2)‒Ru(1)
87.98(3), N(1)‒Ni(1)‒S(2) 168.38(8), N(2)‒Ni(1)‒S(1) 168.10(8).
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Fig. 2. Molecular structure of one anion of [CpRu{Ni(L2-Me)}(PPh3)]Cl EtOH (6 EtOH), with
thermal ellipsoids drawn at the 40% probability level. Solvent molecules and the counter anion are
omitted for clarity. Selected bonds (Å) and angles (°): Ru(1)‒S(1) 2.4570(8), Ru(1)‒S(2) 2.3990(7),
Ru(1)‒P(1) 2.3297(8), Ru(1)‒C(1) 2.187(3), Ru(1)‒C(2) 2.171(3), Ru(1)‒C(3) 2.157(3), Ru(1)‒C(4)
2.173(3), Ru(1)‒C(5) 2.192(3), Ru(1)···Ni(1) 3.116, Ni(1)‒N(1) 1.952(2), Ni(1)‒N(2) 1.896(2),
Ni(1)‒S(1) 2.1801(8), Ni(1)‒S(2) 2.1656(8), C(6)‒S(1) 1.791(3), C(7)‒S(2) 1.798(3), C(6)‒N(3)
1.288(4), C(7)‒N(4) 1.307(4), C(6)‒N(5) 1.343(4), C(7)‒N(6) 1.333(4), C(10)‒N(1) 1.301(4),
C(13)‒N(2) 1.286(4), N(1)‒N(3) 1.418(4), N(2)‒N(4) 1.411(3); S(2)‒Ru(1)‒S(1) 77.83(3),
S(2)‒Ru(1)‒P(1) 88.35(3), S(1)‒Ru(1)‒P(1) 92.45(3), N(2)‒Ni(1)‒N(1) 99.46(10), S(1)‒Ni(1)‒S(2)
89.17(3), N(1)‒Ni(1)‒S(1) 87.32(8), N(2)‒Ni(1)‒S(2) 83.89(7), Ni(1)‒S(1)‒Ru(1) 84.22(3),
Ni(1)‒S(2)‒Ru(1) 85.95(3), N(1)‒Ni(1)‒S(2) 164.79(8), N(2)‒Ni(1)‒S(1) 173.05(8).
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Fig. 3. Molecular structure of one anion of [CpRu{Ni(L3-Et)}(PPh3)]Cl H2O (7 H2O), with thermal
ellipsoids drawn at the 40% probability level. Solvent molecules and the counter anion are omitted for
clarity. Selected bonds (Å) and angles (°): Ru(1)‒S(1) 2.4570(6), Ru(1)‒S(2) 2.4046(6), Ru(1)‒P(1)
2.3327(6), Ru(1)‒C(1) 2.198(3), Ru(1)‒C(2) 2.173(2), Ru(1)‒C(3) 2.156(2), Ru(1)‒C(4) 2.169(2),
Ru(1)‒C(5) 2.199(3), Ru(1)···Ni(1) 3.139, Ni(1)‒N(1) 1.9554(19), Ni(1)‒N(2) 1.9008(18), Ni(1)‒S(1)
2.1813(6), Ni(1)‒S(2) 2.1632(6), C(6)‒S(1) 1.789(2), C(7)‒S(2) 1.797(2), C(6)‒N(3) 1.294(3),
C(7)‒N(4) 1.303(3), C(6)‒N(5) 1.341(3), C(7)‒N(6) 1.331(3), C(10)‒N(1) 1.294(3), C(13)‒N(2)
1.284(3), N(1)‒N(3) 1.414(3), N(2)‒N(4) 1.413(2); S(2)‒Ru(1)‒S(1) 77.48(2), S(2)‒Ru(1)‒P(1)
88.44(2), S(1)‒Ru(1)‒P(1) 92.61(2), N(2)‒Ni(1)‒N(1) 99.81(8), S(1)‒Ni(1)‒S(2) 88.91(2),
N(1)‒Ni(1)‒S(1) 87.21(6), N(2)‒Ni(1)‒S(2) 83.74(6), Ni(1)‒S(1)‒Ru(1) 84.97(2), Ni(1)‒S(2)‒Ru(1)
86.65(2), N(1)‒Ni(1)‒S(2) 165.07(6), N(2)‒Ni(1)‒S(1) 172.64(6).
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Fig. 4. Product analysis (GC-MS) from reaction of benzaldehyde and ethanol under dihydrogen catalyzed
by complex [RuCl2{(Ni(L2‒Me)}(dmso)2] (2).
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For Table of Contents
Synopsis
Syntheses, characterization and reactivity of dinuclear ruthenium-nickel complexes
with hexane-2,5-dione bis(thiosemicarbazonato) ligands
Duo-Wen Fang, Ai-Quan Jia*, Xian-Ping Dong, Zhifeng Xin, and Qian-Feng Zhang*
A series of bimetallic ruthenium-nickel Ni(µ-S)2Ru complexes based on metalloligands hexane-2,5-dione
bis(thiosemicarbazonato)nickel(II) have been synthesized and characterized, and these bimetallic ruthenium-nickel
complexes could effectively catalyze acetalation of benzaldehyde with ethanol in the presence of H2.
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Highlights
► A series of dinuclear Ni(µ-S)2Ru complexes were synthesized based on NiLN2S2 ligands.
► The Ni(µ-S)2Ru complexes were characterized by single-crystal X-ray crystallography.
► The dinuclear Ni(µ-S)2Ru complexes may catalyze acetalation of benzaldehyde with ethanol in the
presence of H2.
1