Ruthenium complexes of furan- and thiophene-thiolates: Structure of CpRu(dppe)SThi

Article abstract of DOI:10.1016/j.ica.2007.11.002

Complexes of ruthenium containing 2-furan- and 2-thiophene-thiolates with phosphine ligands have been prepared and characterized. The bis(triphenylphosphine) complexes CpRu(PPh₃)₂SR (R = C₄H₃O: Fu (1a), C_4<

Full text of DOI:10.1016/j.ica.2007.11.002

Available online at www.sciencedirect.com
Inorganica Chimica Acta 361 (2008) 2957–2961
www.elsevier.com/locate/ica
Ruthenium complexes of furan- and thiophene-thiolates: Structure
of CpRu(dppe)SThi
a,
b
a
*
Mohammad El-khateeb , Mousa Al-Noaimi , Zainab Al-Amawi ,
Alexander Roller c, Sergiu Shova d
a Chemistry Department, Jordan University of Science and Technology, Irbid 22110, Jordan
b Chemistry Department, Faculty of Science, The Hashemite University, Zarka, Jordan
c Institute of Inorganic Chemistry, University of Vienna, Vienna, Austria
d Department of Chemistry of the Moldova State University, Chsinau, Republic of Moldova
Received 1 August 2007; received in revised form 2 October 2007; accepted 2 November 2007
Available online 7 November 2007
Abstract
Complexes of ruthenium containing 2-furan- and 2-thiophene-thiolates with phosphine ligands have been prepared and characterized.
The bis(triphenylphosphine) complexes CpRu(PPh3)2SR (R = C4H3O: Fu (1a), C4H3S: Thi (1b)) were prepared by the reaction of thio-
lato anions (FuSꢀ or ThiSꢀ) with CpRu(PPh3)2Cl. The one-pot reaction of CpRu(PPh3)2Cl, thiolato anions and L ligands gave
CpRu(L)SR (L = bis(diphenylphosphino)methane: dppm (2); bis(diphenylphosphino)ethane: dppe (3)). The newly prepared complexes
have been characterized by spectroscopic techniques (FT-IR, 1H NMR and 31P NMR) and by elemental analysis. The crystal structure of
CpRu(dppe)SThi (3b) has been determined by X-ray diffraction.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Organometallics; Ruthenium; Cyclopentadienyl; Phosphine; X-ray diffraction; Thiolate; Sulfur; Furan-thiolate; Thiophene-thiolate
1. Introduction
produced
the
carbonyl-substituted
complexes
CpRu(PPh3)(CO)SR or the nitrosyl salts [CpRu(PPh3)(-
NO)SR]+, respectively [19,21,26]. Protonation and alkyl-
ation of these thiolates occurred at the sulfur center with
the generation of thiols or thioether complex salts [19,27].
The chemistry of ruthenium complexes containing het-
erocyclic thiolates has been studied in our laboratory
[22,28]. The interaction of 2-pyridine thiolate and 2-pyrim-
idine thiolate with CpRu(PPh3)2Cl gave the complexes
CpRu(PPh3)(j2S,N-SR) (R = C5H4N, C5H3N2) in which
the heterocyclic thiolato ligand is bonded to Ru in a chelat-
ing manner through both S and N atoms. Treatment of the
latter complexes with CO at room temperature gave the
mixed carbonyl-phosphine complexes CpRu(PPh3)
(CO)(jS-SR) [28]. The analogous reactions with NO-salt
gave, unexpectedly the nitrosyl complexes [CpRu(PPh3)
The interest in complexes which incorporate thiolato
ligands is stimulated by several important reasons [1–6].
These include the relevance to biological systems [7–13],
industrial applications [14–16], the quest for novel struc-
tures of thiolato complexes and their applications in
organosulfur chemistry [17,18].
The ruthenium thiolato complexes CpRu(PPh3)2SR are
well documented. They have been synthesized by simple
substitution reactions of CpRu(PPh3)2Cl with thiolato
anions [19–25]. These complexes are found to be reactive
due to the presence of two bulky triphenylphosphine
ligands, which have a 145° cone angle [19]. Reactions of
these complexes with CO or NO+ at room temperature
(NO)(jS-HSR)]2+
,
which contain coordinated thiol
*
Corresponding author. Tel.: +962 2 7201000 (x23644); fax: +962 2
ligands. The dppe-complexes CpRu(dppe)(jS-SR) (dppe =
7207110.
Ph2PCH2CH2PPh2) were prepared by the reaction of
E-mail address: kateeb@just.edu.jo (M. El-khateeb).
0020-1693/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.11.002

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M. El-khateeb et al. / Inorganica Chimica Acta 361 (2008) 2957–2961
1
CpRu(PPh3)2Cl, thiolato anions and dppe ligand [28].
However, the reactions of CpRu(PPh3)2Cl with the 2-mer-
captobenzimidazolyl, 2-mercaptobenzoxazolyl and 2-mer-
captobenzthiazolyl thiolates gave the expected thiolato
complexes CpRu(PPh3)2(jS-SR) in which the thiolato
ligand is bonded in a monodentate fashion through the
S-atom of these thiolates [22]. In a similar way to that
described for 2-pyridine- and 2-pyrimidine thiolates, the
complexes CpRu(PPh3)(CO)(jS-SR) and CpRu(L)(jS-
SR) (SR = 2-mercaptobenzimidazolyl, 2-mercaptobenzox-
azolyl, 2-mercaptobenzthiazolyl, L = dppe, dppm) were
obtained [22].
Extending our work on the synthesis of heterocyclic
thiolato complexes of ruthenium [22,28] and searching for
mono- versus bi-dentate coordination of heterocyclic
ligands, we report in this paper the synthesis and character-
ization of ruthenium complexes containing 2-furan- and 2-
thiophene thiolato complexes. We show that the thiolates
employed act as terminal ligands in these complexes.
compounds have been characterized by 31P and H NMR
spectroscopy as well as by elemental analysis. The main
NMR-spectroscopic features of 1 are a singlet in the H
1
NMR spectrum, in the range of 4.15–4.17 ppm for the
Cp-ring protons and a singlet in the 31P NMR spectrum,
in the range of 44.54–44.55 ppm for the equivalent P atoms
of the triphenylphosphine ligands. These Cp protons for 1
are within the same range of chemical shifts observed for
similar thiolato complexes CpRu(PPh3)2SR (R = alkyl,
aryl, pyridine, pyrimidine: 4.12–4.38 ppm) [19,21,28] and
are lower than those observed for CpRu(PPh3)2SR
(SR = 2-mercaptobenzimidazolyl, 2-mercaptobenzoxazol-
yl, 2-mercaptobenzthiazolyl: 4.76–4.85 ppm) [22]. The 31P
NMR signal of 1 is slightly lowfield shifted compared to
those of CpRu(PPh3)2SR (SR = 2-mercaptobenzimidazol-
yl, 2-mercaptobenzoxazolyl, 2-mercaptobenzthiazolyl:
41.89–42.64 ppm) [22].
The formation of the complexes CpRu(L)SR [L = dppm
(2), dppe (3)] were achieved by the one-pot reaction of
CpRu(PPh3)2Cl, thiolato anions and excess L ligands in
refluxing THF for 4 h (Scheme 1) as reported for analogous
reactions [19,22,28]. Complexes 2 and 3 are less air sensitive
than 1. The 1H NMR spectra of 2 and 3 display a singlet (for
2: 4.90–4.92 ppm and for 3: 4.68–4.72 ppm) for the Cp-pro-
ton resonances. These signals are downfield shifted com-
pared to those of 1 and upfield shifted compared to those
of CpRu(L)SR (SR = 2-mercaptobenzimidazolyl, 2-merca-
ptobenzoxazolyl, 2-mercaptobenzthiazolyl, L = dppm:
5.07–5.13, dppe: 5.00–5.04 ppm) [22]. The resonances of
the protons of the heterocyclic thiolato group of complexes
2 and 3 appear as three sets, each set as a doublet of doublet
in the range of 6.20–6.52 ppm. The methylene protons of the
dppm ligand in 2 appear as two multiplets (due to coupling
to each other and to both P-atoms) because they are diaste-
reotopic protons. The phenyl protons are observed as multi-
plets in the aromatic region. The 31P NMR spectra for
complexes 2 showed a single peak in the range of 17.63–
17.65 ppm. The corresponding peaks of 3 lie in the range
of 84.99–85.90 ppm. These peaks are also low-field shifted
compared to those for cyclopentadienyl thiolato com-
plexes CpRu(dppm)SR (14.20–15.80 ppm) [19,21], and to
CpRu(L)SR (SR = 2-mercaptobenzimidazolyl, 2-merca-
ptobenzoxazolyl, 2-mercaptobenzthiazolyl, L = dppm:
14.20–14.69, dppe: 81.08–81.38 ppm) [22].
2. Results and discussion
2.1. Synthesis and characterization
Ruthenium complexes of the formulae CpRu(PPh3)2-
SFu and CpRu(PPh3)2SThi (Fu = C4H3O (1a), Thi =
C4H3S (1b)) are readily prepared by the reaction of
CpRu(PPh3)2Cl with the thiolato anions (FuSꢀ, ThiSꢀ)
in refluxing THF for a short time (Scheme 1). The thiolato
anions were generated by the lithiation of the five mem-
bered heterocyclic compound using MeLi followed by the
addition of elemental sulfur. These ligands were used as
solutions and were not isolated as solids.
The yellow complexes 1 are air stable as solids but
highly sensitive to air in solution. They are soluble in most
common organic solvents and are insoluble in hexane. The
+ MeLi +S8
E
-Cl-
S-
Ru
+
Ru
E
Ph3P
Cl
Ph3P
S
E
PPh3
PPh3
2.2. Crystal structure of 3b
1
-Cl-
P-P
Fig. 1 shows the ORTEP drawing of two crystallograph-
ically independent molecules of 3b with selected bond
lengths and bond angles. The Ru-C bonds of the Cp-ligand
˚
ranging from 2.210(6) to 2.240(6) A are similar to those
Ru
observed for the analogous CpRu-containing complexes,
P
n
S
˚
E
(e.g. CpRu(dppe)SCO2Bu : 2.200(2)–2.240(2) A, CpRu-
P
n
˚
(PPh3)2SCO2Bu : 2.202(2)–2.230(2) A) [29]. The Ru–S dis-
2, 3
˚
tances in 3b [2.4357(15) and 2.4287(16) A] lie within the
E = O (a), S (b), P-P= Ph2PCH2PPh2 (dppm) 2, Ph2PCH2CH2PPh2 (dppe) 3
range found for the complexes CpRu(L)(L0)SX (X ¼
SSiPri , SC„CPh, SCOCH2Ph) [30,25,31]. The Ru–P bond
Scheme 1.
3

M. El-khateeb et al. / Inorganica Chimica Acta 361 (2008) 2957–2961
2959
Hexane and tetrahydrofuran were dried over sodium-benzo-
phenone and ethanol by using sodium. Ruthenium chloride
hydrate, thiophene, furan, triphenylphosphine, bis(diphen-
ylphosphino)ethane and bis(diphenylphosphino)methane
were obtained from Across and were used without any fur-
ther purification. The reagent CpRu(PPh3)2Cl was prepared
as previously described [33].
Melting points were measured on a smart melting point
apparatus and were uncorrected. 1H and 31P NMR spectra
were recorded on a Bruker-Avance 400 MHz spectrometer
at 400 MHz and 161.3 MHz, respectively. All chemical
shifts are quoted in ppm downfield of TMS (1H) or 85%
phosphoric acid (31P) and referenced using the chemical
shifts of residual solvent resonances. Elemental analyses
were performed at the Institute of Organic and Macromo-
lecular Chemistry, FSU-Jena, Germany.
3.2. General procedure for the preparation of
CpRu(PPh3)2SR, 1
A 100 mL Schlenk flask equipped with a reflux condenser
was charged with 50 mL of THF and CpRu(PPh3)2Cl
(0.50 g, 0.72 mmol). A freshly prepared solution of the
thiolato anions (1.0 mmol) was added and the resulting
mixture was refluxed for 1 h. The solvent was removed
under vacuum to about 2 mL and then 50 mL of hexane
was added. On standing at 4 °C overnight the solution pro-
duced an orange-brown solid which was separated by filtra-
tion, washed several times with cold hexane and dried in
vacuum.
Fig. 1. ORTEP drawing of CpRu(dppe)SThi (3b) with atom numbering
scheme and thermal ellipsoids drawn at the 50% probability level.
˚
Hydrogen atoms were omitted for clarity. Selected bond lengths (A) and
bond angles (°): Ru1–C27 2.240(6), Ru1–C28 2.225(6), Ru1–C29 2.230(6),
Ru1–C30 2.218(6), Ru1–C31 2.240(6), Ru1–P1 2.2796(16), Ru1–P2
2.2688(15), Ru1–S1 2.4357(15), S1–C35 1.766(7); S2–C35 1.721(9), S2–
3.2.1. CpRu(PPh3)2SFu 1a
˚
Yield: 70%. M.p.: 93–94 °C. 1H NMR (C6D6): d 4.17 (s,
C32 1.689(9) A, P1–Ru–P2 83.33(5), P1–Ru1–S1 90.66(5), P2–Ru1–S1
3
4
83.65(5), Ru1–S1–C35 110.6(2), S1–C35–S2 122.0(6), S1–C35–C34
128.8(10), S2–C35–C34 108.7(8)°, Ru2–C62 2.219(6), Ru2–C63 2.231(6),
Ru2–C64 2.232(6), Ru2–C65 2.210(6), Ru2–C66 2.218(6), Ru2–P3
2.2612(17), Ru2–P4 2.2856(16), Ru2–S3 2.4287(16), S3–C70 1.771(7);
5H, Cp), 6.80 (dd, 1H, C4H3O, J = 3.4 Hz, J = 1.1 Hz),
6.98 (m, 18H, PPh3), 7.52 (m, 12H, PPh3), 7.79 (m, 2H,
C4H3O). 31P NMR (C6D6): d 44.55. Anal. Calc. for
C45H38OP2RuS: C, 68.43; H, 4.85; S, 4.06. Found: C,
67.87; H, 4.65; S, 3.85%.
˚
S4–C70 1.743(7), S4–C67 1.702(8) A, P3–Ru2–P4 83.39(6), P3–Ru2–S3
84.00(6), P4–Ru2–S3 92.10(6), Ru2–S3–C70 109.2(2), S3–C70-S4 120.5(4),
S3–C70–C69 129.3(6), S4–C70–C69 109.0(5)°.
3.2.2. CpRu(PPh3)2SThi 1b
1
lengths in 3b [2.2796(16), 2.2688(15), 2.2612(17) and
Yield: 82%. M.p.: 117–119 °C. H NMR (C6D6): d 4.15
˚
2.2856(16) A] are comparable to those of CpRu(dppe)SCO2-
(s, 5H, Cp), 6.79 (dd, 1H, C4H3S, 3J = 3.6 Hz,
4J = 1.0 Hz), 6.96 (m, 18H, PPh3), 7.52 (m, 12H, PPh3),
7.76 (m, 2H, C4H3S). 31P NMR (C6D6): d 44.54. Anal.
Calc. for C45H38P2RuS2: C, 67.06; H, 4.75; S, 7.96. Found:
C, 66.45; H, 4.58; S, 7.87%.
n
˚
Bu [2.2736(5), 2.2830(5) A] [29] and CpRu(dppe)SSO2-4-
˚
C6H4Cl (2.2749(15), 2.2885(18) A) [32]. The angles of the
three legged structure of 3b are as follows: S1–Ru1–P1 =
90.66(5), S1–Ru1–P2 = 83.65(5), S3–Ru2–P3 = 84.00(6),
S3–Ru2–P4 = 92.10(6), P3–Ru2–P4 = 83.39(6) and P1–
Ru1–P2 = 83.33(5)°. These data are similar to those found
in CpRu(dppm)SX complexes indicating a distorted octa-
hedral geometry around the Ru-center.
3.3. General procedure for the Preparation of CpRu(L)SR,
2, 3
A 100 mL Schlenk flask equipped with a reflux con-
denser was charged with 50 mL THF, CpRu(PPh3)2Cl
(0.50 g, 0.72 mmol) and bis(diphenylphosphino)alkane
(1.00 mmol). A freshly prepared solution of the thiolato
anions (1.00 mmol) was added. The resulting mixture was
refluxed for 4 h. The volatiles were removed under vacuum
and the remaining solid was extracted with toluene
3. Experimental
3.1. General
All manipulations were performed in dry solvents under
nitrogen atmosphere by using standard Schlenk techniques.

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M. El-khateeb et al. / Inorganica Chimica Acta 361 (2008) 2957–2961
Table 1
(3 ꢁ 5.0 mL). The extracts were combined and concen-
trated under vacuum to about 4.0 mL. Addition of
30 mL of cold hexane led to the deposition of an orange
solid, which was collected by removing the mother liquor
and recrystallized from THF/hexane.
Selected crystal data and refinement parameters for CpRu(dppe)SThi, 3b
Empirical formula
Crystal system
Volume (A )
C35H32P2RuS2
monoclinic
5875.0(5)
3
˚
Unit cell dimensions
˚
a (A)
29.7494(16)
10.6068(5)
19.4659(9)
106.969(3)
679.74
1.537
0.71073
0.0571
˚
3.3.1. CpRu(dppm)SFu 2a
b (A)
Yield = 70%. M.p.: 181–183 °C. 1H NMR (C6D6): d
4.72 (m, 1H, PCH2), 4.75 (m, 1H, PCH2), 4.92 (s, 5H,
C5H5), 6.32 (dd, 1H, C4H3O, 3J = 3.2 Hz, 4J = 1.0 Hz),
˚
c (A)
b (°)
Formula weight (g/mol)
Density (Mg/m3)
3
3
6.45 (dd, 1H, C4H3O, J = 3.2 Hz, J = 5.3 Hz), 6.52 (dd,
1H, C4H3O, 3J = 5.3 Hz, 4J = 1.0 Hz), 7.08 (m, 12H,
PPh2), 7.50 (m, 8H, PPh2). 31P NMR (C6D6): d 17.63. Anal.
Calc. for C34H30OP2RuS: C, 62.86; H, 4.65; S, 4.94.
Found: C, 62.49; H, 4.74; S, 5.05%.
˚
k (A)
R[F2 > 2r(F2)]
Crystal size (mm)
Space group
Z
0.18 ꢁ 0.16 ꢁ 0.12
P21/c
4
Index range
Goodness-of-fit
Radiation type
ꢀ35 6 h 6 35, ꢀ12 6 k 6 12, ꢀ23 6 l 6 23
1.081
Mo Ka
0.810
3.3.2. CpRu(dppm)SThi 2b
l (mmꢀ1
h (°)
)
Yield = 72%. M.p.: 171–173 °C. 1H NMR (C6D6): d
4.68 (m, 1H, PCH2), 4.70 (m, 1H, PCH2), 4.90 (s, 5H,
C5H5), 6.30 (dd, 1H, C4H3S, 3J = 3.4 Hz, 4J = 0.9 Hz),
2.19–25.00
0.1556
2
xR(F2)a
a
x ¼ 1=½r2ðF o2Þ þ ð0:0598PÞ ꢂ where P ¼ ðF o2 þ 2F 2c Þ=3.
3
4
6.41 (dd, 1H, C4H3S, J = 3.4 Hz, J = 5.6 Hz), 6.50 (dd,
1H, C4H3S, 3J = 5.6 Hz, 4J = 0.9 Hz), 7.03 (m, 12H,
PPh2), 7.53 (m, 8H, PPh2). 31P NMR (C6D6): d 17.65. Anal.
Calc. for C34H30P2RuS2: C, 61.34; H, 4.54; S, 9.63. Found:
C, 61.50; H, 4.60; S, 9.38%.
rected for absorption using intensities of redundant reflec-
tions. The structure was solved by direct methods and
refined by full-matrix least-squares techniques. Non-hydro-
gen atoms were refined with anisotropic displacement
parameters. H atoms were placed in geometrically calculated
positions and refined as riding atoms in the subsequent
least-squares model refinements. The isotropic thermal
parameters were estimated to be 1.2 times the values of the
equivalent isotropic thermal parameters of the atoms to
which hydrogens were bonded. The following computer pro-
grams were used: structure solution, SHELXS-97 [35] refine-
ment, SHELXL-97 [36] molecular diagrams, ORTEP [37]
scattering factors were taken from the literature [38]. The thi-
ophene unit in the first crystallographically independent
molecule was found to be disordered over two positions with
occupation ratio about 80:20. The corresponding atoms of
the two split parts were refined with restrained geometry
using SADI instruction of SHELXL-97. The thermal displace-
ment parameters of two atoms (C32X and C34X) were
refined using ISOR instruction. Attempts to split the phenyl
ring C44–C49 in two positions failed.
3.3.3. CpRu(dppe)SFu 3a
Yield = 90%. M.p.: 142–144 °C. 1H NMR (C6D6): d
1.83 (m, 2H, PCH2), 2.70 (m, 2H, PCH2), 4.68 (s, 5H,
C5H5), 5.85 (dd, 1H, C4H3O, 3J = 3.2 Hz, 4J = 1.0 Hz),
3
3
6.22 (dd, 1H, C4H3O, J = 3.2 Hz, J = 5.5 Hz), 6.43 (dd,
1H, C4H3O, 3J = 5.5 Hz, 4J = 1.0 Hz), 6.90 (m, 12H,
PPh2), 7.79 (m, 8H, PPh2). 31P NMR (C6D6): d 85.90. Anal.
Calc. for C35H32OP2RuS: C, 63.34; H, 4.86; S, 4.83.
Found: C, 63.25; H, 4.76; S, 4.91%.
3.3.4. CpRu(dppe)SThi 3b
Yield = 85%. M.p.: 224–225 °C. 1H NMR (C6D6): d
2.30 (m, 2H, PCH2), 2.80 (m, 2H, PCH2), 4.72 (s, 5H,
3
4
Cp), 5.90 (dd, 1H, C4H3S, J = 3.4 Hz, J = 1.0 Hz), 6.20
3
3
(dd, 1H, C4H3S, J = 3.4 Hz, J = 5.4 Hz), 6.50 (dd, 1H,
C4H3S, 3J = 5.4 Hz, 4J = 1.0 Hz), 7.12 (m, 12H, PPh2);
7.66 (m, 8H, PPh3). 31P NMR (C6D6): d 84.99. Anal. Calc.
for C35H32P2RuS2: C, 61.84; H, 4.74; S, 9.43. Found: C,
61.67; H, 4.91; S, 8.71%.
4. Supplementary material
3.4. Crystallographic analysis of CpRu(dppe)SThi 3b
CCDC 652224 contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Cen-
tre via www.ccdc.cam.ac.uk/data_request/cif.
Single crystals suitable for X-ray structure determination
were obtained by re-crystallization of 3b from THF/hexane
mixture. X-ray diffraction measurements were performed on
X8APEXII CCD diffractometer with graphite monochro-
Acknowledgements
˚
mated Mo Ka radiation, k = 0.71073 A at 100(2) K. The
crystal data for 3b are shown in Table 1. The crystal was
positioned at 40 mm from the detector and 1390 frames were
measured, each for 40 s over 1° scan width. The data were
processed using SAINT software [34]. Intensity data were cor-
The authors thank the Deanship of Research, Jordan
University of Science and Technology for financial support
(Grant No. 89/2006). Prof. V. Arion is greatly acknowl-
edged for his help in the structure determination.

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