Synthesis of cyclopentadienyl ruthenium complexes containing 5-membered N-heterocyclic thiolates

Article abstract of DOI:10.1016/j.ica.2010.05.022

Mononuclear ruthenium-thiolate complexes of structural type CpRu(PPh ₃)₂SR (1) [R = 2-imidazolyl (a), 1-methylimidazolyl (b), 5-methyl-1,3,5-thiadiazolyl (c) and 5-methyl-4H-1,2,4-triazolyl (d)] are accessible from the reaction of Cp

Full text of DOI:10.1016/j.ica.2010.05.022

Inorganica Chimica Acta 363 (2010) 4134–4139
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Inorganica Chimica Acta
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Note
Synthesis of cyclopentadienyl ruthenium complexes containing 5-membered
N-heterocyclic thiolates
Deeb Taher a, Mousa Al-Noaimi b, Sahar Mohammad c, John F. Corrigan d, Daniel G. MacDonald d,
Mohammad El-khateeb c,
*
a Department of Chemistry, Tafila Technical University, Tafila, Jordan
b Chemistry Department, Faculty of Science, The Hashemite University, Zarqa, Jordan
c Chemistry Department, Jordan University of Science and Technology, Irbid 22110, Jordan
d Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7
a r t i c l e i n f o
a b s t r a c t
Article history:
Mononuclear ruthenium–thiolate complexes of structural type CpRu(PPh3)2SR (1) [R = 2-imidazolyl (a),
1-methylimidazolyl (b), 5-methyl-1,3,5-thiadiazolyl (c) and 5-methyl-4H-1,2,4-triazolyl (d)] are accessi-
ble from the reaction of CpRu(PPh3)2Cl with the corresponding thiolate anions. Reaction of CpRu(PPh3)2Cl
with the heterocyclic-thiolate anions in the presence of the bisphosphine ligands affords CpRu(P–P)SR
[P–P = bis(diphenylphosphino)methane; dppm (2), bis(diphenylphosphino)ethane; dppe (3)]. If CO gas
was bubbled through a THF solution of 1b, the complex CpRu(PPh3)(CO)S(C4N2H5) (4b) is produced.
These ruthenium–heterocyclic thiolate complexes have been characterized by elemental analysis, spec-
troscopy (IR, 1H, 31P{1H} NMR and MS) and cyclic voltammetry for some samples. The solid-state struc-
tures of 3a and 3b are determined by single-crystal X-ray structure analysis.
Received 12 January 2010
Received in revised form 2 May 2010
Accepted 12 May 2010
Available online 20 May 2010
Keywords:
Ruthenium
Heterocyclic-thiolates
5-Memberd N-containing heterocycles
Structure
Chelates
Sulfur
Ó 2010 Elsevier B.V. All rights reserved.
Complexes
1. Introduction
and 2-mercaptobenzthiazolyl, thiophene, or furan-thiolates) to
give CpRu(PPh3)2(
monodentate fashion [24]. Treatment of CpRu(PPh3)(
CpRu(PPh3)2( S-SR) with CO or NOBF4 gave the mixed carbonyl-
phosphine complexes CpRu(PPh3)(CO)( S-SR) or the nitrosyl salts
[CpRu(PPh3)(NO)(
S-HSR)]+ [23,24]. The bis(phosphine)-com-
plexes CpRu(P–P)( S-SR) {P–P = Ph2PCH2CH2PPh2 (dppe),
Ph2PCH2PPh2 (dppm) were prepared by the reaction of
CpRu(PPh3)2Cl, thiolato anions and P–P ligands [23–25].
As part of investigation dealing with the study of heterocyclic
thiolate complexes of ruthenium, we report herein the synthesis
and structural characterization of ruthenium complexes with N-
containing five-membered ring thiolates. These thiolates act as
monodentate ligands.
j
S-SR) where the thiolate is bonded to Ru in a
Transition metal complexes containing sulfur-ligands have at-
tracted much attention due to their central roles in biological sys-
tems [1–4] and catalysis [5–7]. Of particular interest are the
ruthenium–sulfur complexes which are known to exhibit good cat-
alytic activity toward hydrodesulfurization process [8–17]. Several
ruthenium thiolates have been synthesized to model the active
sites of metal-sulfide catalysts of the hydrodesulfurization process
[18–21]. The interaction of thiophene or its analogues with ruthe-
nium has been investigated as models for the hydrodesulfurization
of crude oil [13,14,22]. In our lab, we studied the interaction of het-
erocyclic thiolates with ruthenium [23–25]. The reaction of
CpRu(PPh3)2Cl with 2-pyridine thiolate or 2-pyrimidine thiolate
j
2S,N-SR) or
j
j
j
j
produced the complexes CpRu(PPh3)(j
2S,N-SR) (R = C5H4N,
C5H3N2) where the heterocyclic thiolato ligand is bonded to Ru in
a chelating manner through both S and N atoms [23]. On the other
hand, the same Ru-species reacted with heterocyclic-thiolate an-
ions (RS = 2-mercaptobenzimidazolyl, 2-mercaptobenzoxazolyl
2. Experimental
2.1. Materials
All reactions and manipulations were carried out in an inert
atmosphere of dinitrogen using standard Schlenk techniques. Sol-
vents were purified by distillation (dichloromethane: P2O5; n-hex-
ane, toluene, tetrahydrofuran: sodium/benzophenone).
* Corresponding author. Tel.: +962 2 7201000; fax: +962 2 7201071.
E-mail address: kateeb@just.edu.jo (M. El-khateeb).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.05.022

D. Taher et al. / Inorganica Chimica Acta 363 (2010) 4134–4139
4135
2.2. Synthesis of CpRu(PPh3)2SR (1)
2.3.1. CpRu(dppm)S(C3N2H3) (2a)
Yield = 87% (0.38 g, 0.59 mmol). M.p.: 144–145 °C. EI-MS: m/z
(rel. int. %) 651 (93) [M+], 551 (100) [M+ꢀC3N2H3S]. 1H NMR
(C6D6): d 4.30 (m, 1H, Ph2PCH2), 4.66 (m, 1H, Ph2PCH2), 5.12 (s,
5H, Cp), 5.81 (bs, 1H, NH), 6.99 (m, 12H, PPh2), 7.14 (bs, 1H,
C3N2H3), 7.31 (bs, 1H, C3N2H3), 7.51 (m, 8H, PPh3). 31P NMR
(C6D6): d 13.00. Anal. Calc. for C33H30N2P2RuSꢁTHF (%): C, 61.48;
H, 5.44; S, 4.44; N, 3.88. Found: C, 61.03; H, 4.98; S, 4.02; N, 3.13%.
Heterocyclic thiol (1.0 mmol) was dissolved in 50 mL of THF
and cooled to ꢀ78 °C. Methyllithium (1.6 M in diethylether,
0.70 mL, 1.12 mmol) was dropwise added. The cooling bath was re-
moved after 10 min and the reaction mixture was stirred for
15 min at room temperature. CpRu(PPh3)2Cl (0.50 g, 0.68 mmol)
was added and the resulting mixture was refluxed for 4 h. The vol-
atiles were removed under vacuum and the remaining solid was
dissolved in toluene (10.0 mL) and filtered over celite to ensure re-
moval of LiCl, the supernatant was taken and concentrated under
vacuum to about 4.0 mL, then 30.0 mL of cooled hexane was added,
an orange-yellow precipitate was formed which was collected by
removing the mother liquor and washed several times with cooled
hexane and dried in vacuum.
2.3.2. CpRu(dppm)S(C4N2H5) (2b)
Yield 80% (0.36 g, 0.54 mmol). M.p.: 213–215 °C. EI-MS: m/z
(rel. int. %) 665 (90) [M+], 551 (93) [M+ꢀC4N2H5S]. 1H NMR
(C6D6): d 3.02 (s, 3H, CH3), 4.52 (m, 1H, Ph2PCH2), 4.80 (m, 1H,
Ph2PCH2), 5.30 (s, 5H, Cp), 6.90 (m, 12H, PPh2), 6.99 (bs, 1H,
C3N2H2), 7.01 (bs, 1H, C3N2H2), 7.57 (m, 8H, PPh2). 31P NMR
(C6D6): d 15.23. Anal. Calc. for C34H32N2P2RuS (%): C, 61.53; H,
4.86; S, 4.22; N, 4.83. Found: C, 60.52; H, 4.08; S, 3.90; N, 4.15%.
2.2.1. CpRu(PPh3)2S(C3N2H3) (1a)
Yield = 60% (0.30 g, 0.41 mmol). M.p.: 119–120 °C. EI-MS: m/z
(rel. int. %) 790 (10) [M+], 691 (25) [M+ꢀC3N2H3S], 528 (48)
[M+ꢀPPh3], 429 (35) [M+ꢀC3N2H3PPh3]. 1H NMR (C6D6): d 2.30 (bs,
1H, NH), 4.68 (s, 5H, Cp), 6.29 (bs, 1H, C3N2H3), 6.95 (m, 18H,
PPh3), 7.31 (bs, 1H, C3N2H3), 7.64 (m, 12H, PPh3). 31P NMR
(C6D6): d 42.51. Anal. Calc. for C44H38N2P2RuSꢁTHF (%): C, 66.88;
H, 5.38; S, 3.72; N, 3.25. Found: C, 65.73; H, 4.98; S, 3.15; N, 3.01%.
2.3.3. CpRu(dppm)S(C3N2SH3) (2c)
Yield = 60%(0.28 g,0.41 mmol). M.p.:173–175 °C. EI-MS:m/z(rel.
int. %)682(98)[M+], 550(100)[M+ꢀC3N2H3S2]. 1HNMR(C6D6):d2.06
(s, 3H, CH3), 4.38 (m, 1H, Ph2PCH2), 4.54 (m, 1H, Ph2PCH2), 5.05 (s, 5H,
Cp), 6.82 (m, 12H, PPh2), 7.53 (m, 8H, PPh2). 31P NMR (C6D6): d 15.01.
Anal. Calc. for C33H30N2P2RuS2 (%): C, 58.14; H, 4.44; S, 9.41; N, 4.11%.
Found: C, 57.15; H, 3.92; S, 8.62; N, 3.78%.
2.2.2. CpRu(PPh3)2S(C4N2H5) (1b)
Yield = 73% (0.40 g, 0.50 mmol). M.p.: 93–95 °C. EI-MS: m/z (rel.
int. %) 805 (6) [M+], 691 (36) [M+ꢀC4N2H5S], 542 (56) [M+ꢀPPh3].
1H NMR (C6D6): d 2.91 (s, 3H, CH3), 4.20 (s, 5H, Cp), 5.47 (bs, 1H,
C3N2H2), 5.83 (bs, 1H, C4N2H3), 6.92 (m, 18H, PPh3), 7.63 (m, 12H,
PPh3). 1H NMR (C6D6): d: 42.14. Anal. Calc. for C45H40N2P2RuS
(%): C, 67.23; H, 5.02; S, 3.99; N, 3.48. Found: C, 67.15; H, 4.91; S,
3.50; N, 3.00%.
2.3.4. CpRu(dppm)S(C3N3H4) (2d)
Yield = 65% (0.29 g, 0.44 mmol). M.p.: 163–165 °C. EI-MS: m/z
(rel. int. %) 666 (88) [M+], 551 (95) [M+ꢀC3N3H4S]. 1H NMR
(C6D6): d 3.05 (s, 1H, CH3), 4.44 (m, 1H, Ph2PCH2), 4.69 (m, 1H,
Ph2PCH2), 5.23 (s, 5H, Cp), 6.89 (m, 12H, PPh2), 7.37 (s, 1H,
C2N3H), 7.55 (m, 8H, PPh3). 31P NMR (C6D6): d 15.84. Anal. Calc.
for C33H31N3P2RuS (%): C, 59.63; H, 4.70; S, 4.82; N, 6.32. Found:
C, 58.70; H, 4.23; S, 4.23; N, 6.01%.
2.2.3. CpRu(PPh3)2S(C3N2SH3) (1c)
Yield = 80% (0.45 g, 0.54 mmol). M.p.: 123–125 °C. EI-MS: m/z
(rel. int. %) 691 (38) (M+ꢀC3N2H3S2), 429 (63) (M+ꢀC3N2H3S2PPh3).
1H NMR (C6D6): d 2.14 (s, 3H, CH3), 4.73 (s, 5H, Cp), 6.92 (m, 18H,
PPh3), 7.63 (m, 12H, PPh3). 31P NMR (, C6D6): d 42.09. Anal. Calc. for
2.3.5. CpRu(dppe)S(C3N2H3) (3a)
Yield = 90% (0.41 g, 0.61 mmol). M.p.: 133–135 °C. EI-MS: m/z
(rel. int. %) 665 (95) [M+], 565 (100) [M+ꢀC3N2H3S]. 1H NMR
(C6D6): d 1.95 (m, 2H, PPh2CH2), 2.49 (m, 2H, PPh2CH2), 4.96 (s,
5H, Cp), 5.36 (bs, 1H, NH), 6.95 (m, 12H, PPh2), 7.06 (bs, 1H,
C3N2H3), 7.08 (bs, 1H, C3N2H3), 7.77 (m, 8H, PPh2). 31P NMR
(C6D6): d 81.51. Anal. Calc. for C34H32N2P2RuS: C, 61.53; H, 4.86;
S, 4.83; N, 4.22. Found: C, 60.91; H, 4.18; S, 4.22; N, 3.91%.
C44H38N2P2RuS2 (%): C, 64.30; H, 4.66; S, 7.80; N, 3.41. Found: C,
63.61; H, 4.52; S, 7.75; N, 3.28%.
2.2.4. CpRu(PPh3)2S(C3N3H4) (1d)
Yield = 85% (0.46 g, 0.58 mmol). M.p.: 138–140 °C. EI-MS: m/z
(rel. int. %) 691 (45) [M+ꢀC3N3H4S], 429 (56) [M+ꢀC3N3H4SPPh3].
1H NMR (C6D6): d 2.74 (s, 3H, CH3), 4.77 (s, 5H, Cp), 6.94 (m,
18H, PPh3), 7.45 (m, 6H, PPh3), 7.50 (s, 1H, C2N3H). 31P NMR
(C6D6): d 42.34. Anal. Calc. for C44H39N3P2RuS (%): C, 65.66; H,
4.88; S, 3.98; N, 5.22. Found: C, 65.11; H, 4.63; S, 3.26; N, 5.01%.
2.3.6. CpRu(dppe)S(C4N2H5) (3b)
Yield = 80% (0.37 g, 0.54 mmol). M.p.: 128–130 °C. EI-MS: m/z
(rel. int. %) 679 (99) [M+], 565 (100) [M+ꢀC4N2H5S]. 1H NMR
(C6D6): d 2.02 (m, 2H, PPh2CH2), 2.36 (m, 2H, PPh2CH2), 2.93 (s,
3H, CH3), 5.20 (s, 5H, Cp), 5.48 (bs, 1H, C3N2H2), 5.80 (bs, 1H,
C3N2H2), 7.01 (m, 12H, PPh2), 7.67 (m, 8H, PPh2). 31P NMR (C6D6):
d 80.80. Anal. Calc. for C35H34N2P2RuS (%): C, 62.03; H, 5.06; S,
4.73; N, 4.13. Found: C, 61.69; H, 5.60; S, 4.36; N, 3.90%.
2.3. Synthesis of CpRu(dppm)SR (2), CpRu(dppe)SR (3)
Heterocyclic thiols (1.0 mmol) was dissolved in THF (50 mL)
and cooled to ꢀ78 °C. Methyllithium (1.6 in diethylether,
0.70 mL, 1.12 mmol) was added dropwise. The cooling bath was re-
moved after 10 min and the reaction was stirred for a further
15 min at room temperature. CpRu(PPh3)2Cl (0.50 g, 0.68 mmol)
2.3.7. CpRu(dppe)S(C3N2SH3) (3c)
Yield = 85% (0.40 g, 0.58 mmol). M.p.: 124–125 °C. EI-MS: m/z
(rel. int. %) 565 (100) [M+ꢀC3N2H3S2]. 1H NMR (C6D6): d 1.98 (m,
2H, PPh2CH2), 2.16 (s, 3H, CH3), 2.48 (m, 2H, PPh2CH2), 4.99 (s,
5H, Cp), 6.94 (m, 12H, PPh2), 7.75 (m, 8H, PPh2). 31P NMR (C6D6):
d 80.79. Anal. Calc. for C34H32N2P2RuS2ꢁTHF (%): C, 59.44; H, 5.25;
S, 8.35; N, 3.65% Found: C, 58.51; H, 5.05; S, 7.65; N, 3.49%.
and
bis(diphenylphosphino)methane
or
bis(diphenylphos-
phino)ethane (0.68 mmol) were added and the resulting mixture
was refluxed for 4 h. The volatiles were removed under vacuum
and the remaining solid was dissolved in toluene (10.0 mL). The
resulting solution was filtered over celite to ensure removal of LiCl.
The supernatant was taken and concentrated under vacuum to
about 4.0 mL then 30.0 mL of cooled hexane was added, a light yel-
low precipitate was formed which was collected by removing the
mother liquor and recrystallized from THF/hexane.
2.3.8. CpRu(dppe)S(C3N3H4) (3d)
Yield = 85% (0.39 g, 0.58 mmol). M.p.: 158–160 °C. EI-MS: m/z
(rel. int. %) 679 (98) [M+], (100) [M+ꢀC3N2H4S]. 1H NMR (acetone-
d6): d 2.54 (m, 2H, PPh2CH2), 2.59 (m, 2H, PPh2CH2), 4.99 (s, 5H,
Cp), 7.27 (m, 12H, PPh2), 7.50 (s, 1H, C2N3H), 7.79 (m, 8H, PPh2). 1H

4136
D. Taher et al. / Inorganica Chimica Acta 363 (2010) 4134–4139
NMR (C6D6): d 81.37. Anal. Calc. for C34H33N3P2RuS: C, 60.17; H, 4.90;
S, 4.72; N, 6.19% Found: C, 59.38; H, 4.81; S, 4.12; N, 5.92%.
times with cooled n-hexane and dried in vacuum. Yield = 60%
(0.17 g, 0.30 mmol). M.p.: 181–183 °C. 1H NMR (C6D6): d 3.02 (s,
3H, CH3), 4.92 (s, 5H, Cp), 6.45 (d, 1H, JH–H = 2 Hz, C4N2H5), 6.90
(m, 9H, PPh3), 7.21 (d, 1H, JH–H = 2 Hz, C4N2H5), 7.57 (m, 6H,
PPh3). 31P NMR (C6D6): d 57.36. IR (CH2Cl2): 1950 cmꢀ1. Anal. Calc.
for C28H25N2OPRuS (%): C, 59.04.53; H, 4.42; S, 5.63; N, 4.92.
Found: C, 58.88; H, 4.32; S, 5.23; N, 4.85%.
2.4. Synthesis of CpRu(PPh3)(CO)S(C4N2H5) (4b)
CO gas was bubbled through a THF solution (30 mL) of complex
1b (0.40 g, 0.50 mmol) for 30 min at room temperature. The mix-
ture was stirred under CO-atmosphere for 3 h. The solution was
concentrated under vacuum to about 4.0 mL then 30.0 mL of
cooled hexane was added, a yellow precipitate was formed which
was collected by removing the mother liquor and washed several
2.5. Instrumentation
FT-IR spectra were recorded with a Perkin–Elmer FT-IR 1000
spectrometer (KBr disks or CH2Cl2 solution). NMR spectra were re-
corded on a Bruker Avance 400 MHz spectrometer, operating in the
fourier-transform mode. 1H NMR spectra were recorded at
400 MHz (relative to C6D6, d 7.16, acetone-d6, 2.05). 31P{1H} NMR
spectra were recorded at 161.2 MHz in C6D6 with P(OMe)3 as
external standard (d 139.0, relative to 85% H3PO4). Mass spectra
were performed on a Finnigan MAT 8200 instrument. Melting
points were determined using analytically pure samples, sealed
off in nitrogen-purged capillaries on a Gallenkamp MFB 595 010
melting point apparatus. Microanalyses were performed by the
Institute of Organic and Macromolecular Chemistry, FSU-Jena, Jena,
Germany. CpRu(PPh3)2Cl was prepared by published procedures
[26]. All other chemicals were purchased from commercial suppli-
ers and were used as received. Cyclic voltammetric studies were
performed in dichloromethane using a BAS 100 electrochemical
workstation. Three electrodes were utilized in this system, gold
working electrode; platinum flag counter electrode, and a silver
wire pseudo-reference electrode. For ease of comparison, all poten-
tials are converted to the ferrocene–ferrocenium couple as a refer-
Table 1
Crystal data and structure refinement for 3a and 3b.
3a
3b
CCDC number
Chemical formula
Molecular weight
Crystal system
Space group
Unit cell dimension
a (Å)
728102
728101
C36H36Cl2N2P2RuS
762.64
C
34H32N2P2RuS
663.69
orthorhombic
Pna2(1)
triclinic
ꢀ
P1
20.7860(10)
14.5939(7)
9.5541(4) Å
90
90
90
2898.2(2)
4
1.521
9.2741(3)
10.6145(3)
18.3048(7)
96.983(2)
101.6070(10)
106.760(2)
1658.82(10)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (g cmꢀ3
F(0 0 0)
)
1.527
780
1360
Crystal size (mm)
Reflections measured
Unique reflections
0.30 ꢂ 0.18 ꢂ 0.10 0.28 ꢂ 0.18 ꢂ 0.15
12 255
33 137
ence (E0 = 0.00 V,
DE = 125 mV) [27–29]. The cell temperature was
5452
9702
maintained at 25.0 0.1 °C. Tetrabutylammonium tetrafluorobo-
rate was used as the supporting electrolyte.
Data/restraints/parameters
5452/1/361
0.909
0.0628, 0.1391
0.1220, 0.1758
0.858, ꢀ1.317
9702/0/393
0.972
0.0585, 0.1247
0.1219, 0.1520
1.138, ꢀ1.686
Goodness-of-fit (GOF) on F2
a
R1a, wR2 [I P 2
r(I)]
a
R1a, wR2
2.6. Crystallography
Maximum and minimum peak in
final Fourier map (e Åꢀ3
)
X-ray structural analyses were carried out on an Enraf-Nonius
Kappa CCD single-crystal X-ray diffractometer. Table 1 summarizes
2
¼ 1=r2ðF2o Þ þ ð0:0598PÞ where P ¼ ðFo2 þ 2F2c Þ=3.
a
x
Ru
Ru
RSLi
+
LiCl
+
Ph3P
Cl
Ph3P
SR
PPh3
PPh3
(1)
CO
P-P
Ru
+
PPh3
Ru
+
PPh3
Ph2P
SR
Ph3P
SR
PPh2
CO
4b
(2),
(3)
P-P = dppm
dppe
N
N
N
N
N
NMe
(b)
(a)
(c)
RS =
Me
S
(d)
S
S
S
S
N
H
N
N
Me
Scheme 1. Synthesis of complexes.

D. Taher et al. / Inorganica Chimica Acta 363 (2010) 4134–4139
4137
the structural data of 3a and 3b. Data were corrected for Lorentz
and polarization effects. The SHELXTL (G.M. Sheldrick, Madison, WI)
program package was used to solve (direct methods) and refine
the structures. All non-hydrogen atoms, with the exception of dis-
ordered carbon centers, were refined with anisotropic thermal
parameters. Hydrogen atoms were included as riding on their
respective carbon atoms.
lected bond distances and angles of these complexes are
summarized in Table 2. The structures of 3a and 3b consist of a
simple complex formed by coordination of the 2-mercapto-1-imid-
azolyl or 2-mercapto-1-methylimidazolyl (3b) ligand to the
CpRu(dppe) fragment. These complexes have a three-legged piano
stool structure with the thiolate ligand and the two P-atoms of the
dppe-ligand are the legs while the Cp ring (bonded to ruthenium in
an
g
5 fashion) as its base. In both structures 3a and 3b, the planar
five-membered ring is attached to the Ru-center by the sulfur atom
with a Ru–S bond lengths of 2.416(2) and 2.4153(10) Å for 3a and
3b, respectively. These bond distances are similar for those
3. Results and discussion
3.1. Synthesis
The heterocyclic-thiolato complexes, CpRu(PPh3)2SR (1)
[R = imidazolyl: C3N2H3 (a), 1-methylimidazolyl: C4N2H5 (b), 5-
methyl-1,3,5-thiadiazolyl: C3N2SH3 (c) and 5-methyl-4H-1,2,4-
triazolyl C3N3H4 (d)] are accessible in a two-step synthesis proto-
col: selective metallation of the heterocyclic thiol by using excess
of MeLi, followed by the reaction of the generated heterocyclic an-
ion with Ru-chloride (Scheme 1). The work-up includes removal of
LiCl, accomplished by dissolving the complexes in toluene and fil-
tration over celite. Complexes 1a–d can be precipitated from tolu-
ene solution by slow addition of n-hexane. In the presence of the
bisphospine-ligands
(dppm,
dppe),
the
same
reaction
(CpRu(PPh3)2Cl + LiSR) gives the chelate complexes CpRu(dppm)SR
(2) and CpRu(dppe)SR, (3) (Scheme 1). If CO gas is bubbled through
a THF solution of 1b, the complex CpRu(PPh3)(CO)S(C4N2H5); 4b is
produced in which
(Scheme 1).
a CO group replaced one PPh3 ligand
Fig. 1. X-ray structure of CpRu(dppe)S(C3N2H3) (3a).
The thiolato complexes 1–3 and 4b are air-stable solids but air-
sensitive in solution. They are yellow solids, isolated in 60–87%
yield and are soluble in polar organic solvents. These complexes
were characterized by elemental analysis and spectroscopy (IR,
1H, 31P{1H} NMR and MS). The solid-state structures of 3a and 3b
by X-ray diffraction are determined. The 1H NMR spectra of the
thiolate complexes show a singlet in the ranges of 4.68–4.77,
4.96–5.20, 5.05–5.30 ppm and at 4.92 ppm characteristic for the
Cp-ring protons of 1, 2, 3 and 4b, respectively. These ranges are
consistent with the ranges observed for the alkyl or aryl thiolate
complexes CpRu(L)(L’)SR (L = L0 = PPh3, ½ dppe, ½ dppm, L = PPh3,
L0 = CO) [24,25,30–32]. The spectra of these complexes exhibit
well-resolved resonance signals with the expected coupling pat-
tern for each of the heterocyclic groups present in these com-
pounds. Their 31P NMR spectra show a singlet in the ranges of
42.09–42.51, 13.00–15.84, 80.79–81.37 and at 57.36 ppm for com-
plexes 1, 2, 3 and 4b, respectively. These ranges of the 31P NMR
data are also similar to those found for the corresponding thiolates
CpRu(L)(L0)SR, thiocarboxylates [24,25,30–32] CpRu(L)(L0)SCOR
[33] and thiocarbonates CpRu(L)(L0)SCO2R [34]. The IR spectrum
of 4b displays a strong band at 1946 cmꢀ1 for the terminal car-
bonyl group bonded to ruthenium. This value is comparable to
those reported for analogues ruthenium alkyl or aryl-thiolates
[24,25,30–32]. The TOF-MS spectra of 1–3 and 4b show the molec-
ular ion peak for most complexes. For compounds 1c, 1d and 2c,
TOF-MS spectra show the highest peak as (M+ꢀSR). The base peak
for complex 1 is found to be [CpRu(PPh3)2]+, for 2 is [CpRu(dppm)]+
and for 3 is [CpRu(dppe)]+. Further ions by loss of the phosphine
groups are also observed.
Fig. 2. X-ray structure of CpRu(dppe)S(C4N2H5) (3b).
Table 2
Selected bond length (Å) and bond angle (°) for compounds 3a and 3b.
3a
3b
Ru(1)–C(33)
Ru(1)–C(29)
Ru(1)–C(30)
Ru(1)–C(32)
Ru(1)–C(31)
Ru(1)–S(1)
2.195(10)
2.224(9)
2.235(10)
2.260(9)
2.276(8)
2.416(2)
2.260(2)
2.274(3)
1.761(9)
87.40(9)
87.82(9)
82.68(9)
109.6(3)
Ru(1)–C(1)
Ru(1)–C(2)
Ru(1)–C(3)
Ru(1)–C(4)
Ru(1)–C(5)
Ru(1)–S(1)
Ru(1)–P(1)
Ru(1)–P(2)
2.237(4)
2.231(4)
2.198(4)
2.209(4)
2.231(4)
2.4153(10)
2.2692(11)
2.2644(11)
1.747(4)
87.32(4)
85.27(4)
83.98(4)
111.64(14)
3.2. Crystal structures
Ru(1)–P(1)
Ru(1)–P(2)
S(1)–C(25)
The X-ray structures of 3a and 3b were determined by single-
crystal X-ray structure analysis. Single-crystals of these complexes
could be obtained by slow vapor diffusion of n-pentane into a
dichloromethane solution containing 3a and 3b at 25 °C. The struc-
tures of 3a and 3b are presented in Figs. 1 and 2, respectively. Se-
S(1)–C(32)
P(1)–Ru(1)–S(1)
P(2)–Ru(1)–S(1)
P(1)–Ru(1)–P(2)
Ru(1)–S(1)–C(25)
P(1)–Ru(1)–S(1)
P(2)–Ru(1)–S(1)
P(2)–Ru(1)–P(1)
Ru(1)–S(1)–C(32)

4138
D. Taher et al. / Inorganica Chimica Acta 363 (2010) 4134–4139
Table 3
tive example, the cyclic voltammogram for complex 3c is shown in
Cyclic voltammetry data of CpRu(PPh3)2SR complexes.a
Fig. 3. Our concern here is the quasi-reversible single oxidation
wave lies between ꢀ0.112 to ꢀ0.25 V. This wave is assigned to
Ru(III/II) and was obtained from an average of anodic and cathodic
peak potentials. On the CV timescale, complexes 1(c, d), 2(c, d) and
3(c, d) displayed chemically quasi-reversible oxidation processes
at rate of 100 mV sꢀ1. The one electron nature of this oxidation
has been verified by comparing its current height (ip) with that
of the standard ferrocen/ferrocenium couple under identical exper-
imental conditions. The redox potentials (E1/2) are independent of
the various scan rates, supporting quasi-reversibility. Complexes
1(c, d), 2(c, d) and 3(c, d) also displayed one chemically irreversible
oxidation process suggesting instability of the more highly oxi-
dized state. However, the shift for Ru(III/II) couples is affected with
the electron-donor capability of the corresponding ligands. For
these complexes, the formal potentials decreased in the order
dppm < dppe < (PPh3)2, although the total difference in oxidation
potential spanning is relatively small (60 mV). These complexes
are easily oxidized relative to the parent [CpRuL2Cl] analogue.
The small cathodic shift for Ru(III/II) couples in the [CpRuL2SR]
complexes can be explained by the difference in the electron den-
sity at the metal center influenced by the nature of the heterocyclic
group.
Compound
D
E (mV)
E1/2 (V)c
Eopx (V)b
Erped (V)
CpRu(PPh3)2Cl
CpRu(dppm)Cl
CpRu(dppe)Cl
1c
1d
2c
2d
3c
3d
360
340
110
362
104
90
122
210
108
0.10 [36]
0.03 [36]
0.05 [36]
ꢀ0.153
ꢀ0.112
ꢀ0.206
ꢀ0.25
0.028
0.164
ꢀ0.161
ꢀ0.189
ꢀ0.102
ꢀ0.221
ꢀ0.334
0.06
ꢀ0.251
ꢀ0.311
ꢀ0.312
ꢀ0.313
ꢀ0.207
ꢀ0.239
a
Solvent dichloromethane, supporting electrolyte Bu4NBF4 (0.10 M), scan rate
(0.1 V sꢀ1), gold disk working electrode, Pt-wire auxiliary electrode, reference
electrode Ag at 25 °C.
b
The cathodic peak maximum.
E1=2 ðVÞ ¼ ðEopx þ ErpedÞ=2.
c
reported of the known Ru(II) thiolato complexes [23–25,30–32].
The Ru–P bond lengths in 3a (2.260(2), 2.274(3) Å) and in 3b
(2.2692(11), 2.2644(11) Å) are close to the corresponding values
of CpRu(dppe)SCOCO2Et (2.2772(6), 2.2527(6) Å) [35]. Angles
around Ru-center are consistent with the usual distorted octahe-
dral coordination usually found in these complexes. The bite angles
[P–Ru–P] of the dppe-ligand are 82.68(9)° for (3a) and 83.98(4)° for
(3b). The other two angles of the three-legged structure of 3a are
P1–Ru–S = 87.40(9)° and P2–Ru–S = 87.82(9)°, and for compound
3b P1–Ru–S 87.40(9)° and P2–Ru–S = 87.82(9)°. These data are
similar to those found in CpRu(dppe)SX (X = R, COR, CO2R) com-
plexes indicating a distorted octahedral geometry around the Ru-
center [24,25,30–35].
4. Supplementary material
CCDC 728102 and 728101 contain the supplementary crystallo-
graphic data for 3a and 3b. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgement
3.3. Electrochemistry
The financial support from the Deanship of Scientific Research,
JUST (Grant No. 123/2007) is greatly acknowledged.
The electron-transfer behavior of the complexes in dichloro-
methane solution was examined by cyclic voltammetry and the
corresponding results are summarized in Table 3. As a representa-
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