Synthesis and crystal structures of π-tetramethylthiophene complexes of ruthenium(II)

Article abstract of DOI:10.1016/S0277-5387(99)00062-5

The compound [{Ru(η⁵-C₄Me₄S)Cl(μ-Cl)}₂] reacts with a range of bases L to give the simple monomeric adducts [{Ru(η⁵-C₄Me₄S)Cl₂L] (L=PPhMe₂ 1, P(OMe)₃ 2, CO 3, NC₅H₄ 4, NC₅H₄CN 5). Reaction of [{Ru(η⁵-C₄Me₄S)Cl(μ-Cl)}₂] with 2,2′-bipyridyl/NH₄[PF₆] gives the cationic complex [{Ru(η⁵-C₄Me₄S)Cl(bipy)][PF₆] 6 which reacts further with PPhMe₂/Ag[PF₆] to give [{Ru(η⁵-C₄Me₄S)(PPhMe ₂)(bipy)][PF₆]₂ 7. In the presence of a tripodal ligand, such as [HB(Pz)₃]^-, all the chlorides are displaced from the ruthenium in a single synthetic step, giving [{Ru(η⁵-C₄Me₄S){HB(Pz) ₃}][PF₆] 8. Interestingly when [{Ru(η⁵-C₄Me₄S)Cl(μ-Cl)}₂] is placed in an aqueous solution in the absence of additional ligands the binuclear face-sharing bi-octadedral complex cation [(η⁵-C₄Me₄S)Ru(μ-Cl) ₃Ru(η⁵-C₄Me₄S)]⁺ is formed, and can be trapped out as its hexafluorophosphate salt [Ru₂(η⁵-C₄Me₄S) ₂(μ-Cl)₃][PF₆] 9. Compounds 1-9 have been characterised fully by spectroscopic methods and crystal structure determinations of 1, 7, 8, and 9 are reported. Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(99)00062-5

Polyhedron 18 (1999) 1825–1833
Synthesis and crystal structures of p-tetramethylthiophene complexes of
ruthenium(II)
Anthony Birria, Jonathan W. Steedb, Derek A. Tochera ,
*
aDepartment of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
bDepartment of Chemistry, King’s College London, Strand, London WC2R 2LS, UK
Received 15 December 1998; accepted 26 February 1999
Abstract
The compound [hRu(h5-C4Me4S)Cl(m-Cl)j2] reacts with a range of bases L to give the simple monomeric adducts [hRu(h5-
C4Me4S)Cl2L] (L5PPhMe2 1, P(OMe)3 2, CO 3, NC5H4 4, NC5H4CN 5). Reaction of [hRu(h5-C4Me4S)Cl(m-Cl)j2] with 2,29-
bipyridyl/NH4[PF6] gives the cationic complex [hRu(h5-C4Me4S)Cl(bipy)][PF6] 6 which reacts further with PPhMe2 /Ag[PF6] to give
[hRu(h5-C4Me4S)(PPhMe2)(bipy)][PF6]2 7. In the presence of a tripodal ligand, such as [HB(Pz)3]2, all the chlorides are displaced from
the ruthenium in a single synthetic step, giving [hRu(h5-C4Me4S)hHB(Pz)3j][PF6] 8. Interestingly when [hRu(h5-C4Me4S)Cl(m-Cl)j2] is
placed in an aqueous solution in the absence of additional ligands the binuclear face-sharing bi-octadedral complex cation [(h5-
C4Me4S)Ru(m-Cl)3Ru(h5-C4Me4S)]1 is formed, and can be trapped out as its hexafluorophosphate salt [Ru2(h5-C4Me4S)2(m-Cl)3][PF6]
9. Compounds 1–9 have been characterised fully by spectroscopic methods and crystal structure determinations of 1, 7, 8, and 9 are
reported.
1999 Elsevier Science Ltd. All rights reserved.
1. Introduction
of [hRu(h5-C4Me4S)Cl(m-Cl)j2] [21] which was employed
as a synthon for two series of closely related complex ions
[Ru(h5-C4Me4S)(h6-arene)]21 and [hRu(h5-C4Me4S)(h5-
thiophene)]21 [22]. The organometallic chemistry of the
p-thiophene rings in these systems has been extensively
explored by Rauchfuss in a series of elegant papers [23–
27], and related work on the ruthenium(0) derivatives has
also been described [28–30]. In contrast the coordination
chemistry of [hRu(h5-C4Me4S)Cl(m-Cl)j2] remains rela-
tively unexplored. The only significant coordination
chemistry which has been reported for the binuclear
compound is the formation of the simple bridge-cleaved
The study of transition metal thiophene compounds is an
area of great current interest. This is due in no small part to
the importance of the hydrodesulfurisation reaction in the
petroleum industry [1–5]. This reaction converts the
organosulfur compounds which contaminate crude oil into
alkanes, alkenes, and hydrogen sulfide, which can then be
easily removed. Although there are a wide range of
organosulfur compounds found in crude oil it is the
thiophenes and benzothiophenes which are the most dif-
ficult to desulfurise. The industrial process is carried out
heterogeneously over a CoMo/Al2O3 or CoW/Al2O3 cata-
lyst. Increased activity of the catalyst has been observed
when late transition metals are added as ‘promoters’ to the
catalyst [1–4]. For these reasons thiophene and benzo-
thiophene derivatives of elements such as ruthenium [6–9],
rhodium [10–17], and platinum [18–20], and their cata-
lytic reactions, have received considerable attention in
recent years.
adducts
[Ru(h5-C4Me4S)Cl2(PR3)]
and
[Ru(h5-
C4Me4S)Cl2(NH2C6H4Me)] [22], and the preparation of
tris substituted species [Ru(h5-C4Me4S)L3]21 (L5H2O,
NH3, PH3) [21]. A further reaction of note is that [hRu(h5-
C4Me4S)Cl(m-Cl)j2] reacts with (Me3Si)2S to give the
unusual polynuclear compound [hRu(h5-C4Me4S)(m-
Cl)j3(m3-S)] [21]. Given the synthetic utility, and the
increasing recognition of catalytic activity, demonstrated
by the isoelectronic and isostructural series of compounds
[hRu(h6-arene)(m-Cl)Clj2] [31,32] there is clearly consid-
erable scope for, and persuasive arguements in favour of,
developing the coordination chemistry of [hRu(h5-
C4Me4S)Cl(m-Cl)j2]. With that goal in mind we now
present a range of compounds, including key crystal
Almost 10 years ago Rauchfuss reported the preparation
*Corresponding author. Tel.: 144-171-504-4709; fax: 144-171-380-
7463; Web: http://calcium.chem.ucl.ac.uk/webstuff/people/tocher/in-
dex.html
E-mail address: d.a.tocher@ucl.ac.uk (D.A. Tocher)
0277-5387/99/$ – see front matter
PII: S0277-5387(99)00062-5
1999 Elsevier Science Ltd. All rights reserved.

1826
A. Birri et al. / Polyhedron 18 (1999) 1825–1833
structures, whose chemistry mimics that of the ‘Ru(h6-
arene)’ moiety, but which have not been fully described
previously for the thiophene derivatives.
ppm. Infrared (Nujol, CsI): n(Ru–Cl) 289(w) cm21. Mass
spectrum (FAB): m/z 450, [M]1; 415, [M-Cl]1; 380,
[M-Cl-Cl]1, 277 [M-PPhMe2-Cl].
2.2.2. [Ru(h5-C4Me4S)Cl2(P(OCH3 )3 )] 2
[hRu(h5-C4Me4S)Cl(m-Cl)j2] (0.070 g, 0.11 mmol) was
dissolved in dichloromethane (30 cm3) to which an excess
of P(OCH3)3 (0.05 cm3) was added and the reaction
mixture stirred for 1 h. The solution was concentrated to
ca. 10 cm3 and hexane (40 cm3) was added, giving an
orange precipitate. The solid was isolated by filtration and
washed with hexane (50 cm3) and diethylether (30 cm3)
and then dried in vacuo. Yield: 0.080 g, 0.18 mmol, 82%.
Anal. (Found: C, 29.92, H, 4.77%; Calc. for
RuC11H21O3Cl2PS: C, 30.28, H, 4.86%). 1H NMR
[CDCl3, 2608C]: d 1.99 (s, 6H, TMT), d 2.00 (s, 6H,
2. Experimental section
2.1. General and instrumental
Infrared spectra were recorded on a Nicolet-205 spec-
trometer between 4000 and 400 cm21, as their KBr discs
and between 4000 and 250 cm21 on a Perkin-Elmer 457
1
grating spectrometer, as nujol mulls on CsI discs. The H
NMR spectra were recorded on either a Varian VXR-400 or
Bruker-spectrospin AC-300 instruments, (referenced inter-
nally against respective deuterated solvents: CDCl3, d
7.27; (CD3)2CO, d 2.04; CD2Cl2, d 5.32 ppm). Elemental
analyses were carried out by the departmental service at
University College London. Fast atom bombardment
(FAB) mass spectra were recorded by the University of
London Intercollegiate Research Service (ULIRS) at the
London School of Pharmacy, while positive ion electro-
spray mass spectra were recorded at UCL (assignments
based on the 102Ru isotope). All manipulations were
carried out under anaerobic conditions in a nitrogen
atmosphere using conventional Schlenk-line techniques.
Ruthenium trichloride hydrate was obtained on loan from
Johnson Matthey plc., and was purified before use by
repeated dissolution in water and boiling to dryness.
[hRu(h5-C4Me4S)Cl(m-Cl)j2] was prepared according to
literature methods [21]. Diethylether was distilled from
sodium benzophenone ketyl; dichloromethane was distilled
from CaH2; H2O was distilled over KOH and redistilled
under nitrogen. All reaction solvents were degassed prior
to use, by three repetitions of pump-freeze-thaw cycles.
Pyridine was distilled off KOH, and 4-cyanopyridine was
sublimed under vacuum prior to use. All other reagents
were obtained from the usual commercial sources and were
used as received.
3
TMT); d 3.75 (d, JPH511.0 Hz., 9H, P–OCH3) ppm.
Infrared (KBr): n(PO), 1029(s); d(OPO), 536(w) cm21
,
(Nujol, CsI) n(Ru–Cl) 288(w) cm21. Mass spectrum (FAB):
m/z 436, [M]1; 401, [M-Cl]1; 277, [M-P(OMe)3-Cl]1.
2.2.3. [Ru(h5-C4Me4S)Cl2(CO)] 3
[hRu(h5-C4Me4S)Cl(m-Cl)j2] (0.078 g, 0.13 mmol) was
added to a CO saturated solution of dichloromethane (30
cm3), which was refluxed for 1 h under a gentle stream of
CO. The flask was then sealed under a CO atmosphere and
the solution stirred at room temperature for a further 2 h,
after which time a yellow solid precipitated. The solid was
filtered off and washed with dichloromethane (20 cm3) and
diethylether (20 cm3) and then dried in vacuo. Yield: 0.051
g, 0.15 mmol, 59%. Anal.: (Found: C, 31.16, H, 3.43%.
Calc. for RuC9H12Cl2OS: C, 31.77, H, 3.56%). Infrared
(KBr): n(CO) 1982(s) cm21. Mass spectrum (positive ion
electrospray): m/z 340, [M]1; 305, [M-Cl]1; 277, [M-CO-
Cl]1.
2.2.4. [Ru(h5-C4Me4S)Cl2(NC5H5 )] 4
[hRu(h5-C4Me4S)Cl(m-Cl)j2] (0.070 g, 0.11 mmol) was
dissolved in dichloromethane (30 cm3) to which an excess
of pyridine (0.10 cm3) was added. The reaction mixture
was stirred for 20 h then the solution concentrated to ca. 10
cm3. This resulted in the slow formation of a yellow solid.
Hexane (10 cm3) was added in order to complete the
precipitation. The solid was filtered off and washed with
hexane (20 cm3) and diethylether (40 cm3) and dried in
vacuo. Yield: 0.065 g, 0.17 mmol, 75%. Anal. (Found: C,
39.61, H, 4.27, N, 3.34%. Calc. for RuC13H17Cl2NS: C,
39.90, H, 4.39, N, 3.58%). 1H NMR [CD2Cl2]: d 1.81 (br,
6H, TMT); d 1.88 (br, 6H, TMT); d 7.33 (dd, 2H) d 7.76
(tt, 1H), d 8.87 (br, 2H) ppm. (pyridine resonances).
Infrared (Nujol, CsI) n(Ru–Cl) 284(w) cm21. Mass spectrum
(positive ion electrospray): m/z 391, [M]1; 356, [M-Cl]1.
2.2. Synthesis
2.2.1. [Ru(h5-C4Me4S)Cl2(PPhMe2 )] 1
[hRu(h5-C4Me4S)Cl(m-Cl)j2] (0.144 g, 0.23 mmol) was
dissolved in dichloromethane (30 cm3) to which an excess
of PPhMe2 (0.05 cm3) was added and the reaction mixture
stirred for 2 h. The solution was concentrated to ca. 10 cm3
and hexane was added giving an orange–red precipitate.
The solid was isolated by filtration and washed with
hexane (50 cm3) and diethylether (30 cm3) and then dried
in vacuo. Yield: 0.183 g, 0.41 mmol, 88%. Anal. (Found:
C, 42.38; H, 5.11%. Calc. for RuC16H23Cl2PS: C, 42.67;
1
H, 5.10%). H NMR [CDCl3, 2608C]: d 1.29 (s, 6H,
2
TMT); d 1.85 (d, 6H, JPH511.5 Hz. P–Me); d 1.88 (s,
2.2.5. [Ru(h5-C4Me4S)Cl2(NC5H4CN)] 5
6H, TMT); d 7.45 (m, 3H, m/p-Ph); d 7.68 (m, 2H, o-Ph)
[hRu(h5-C4Me4S)Cl(m-Cl)j2] (0.071 g, 0.11 mmol) was

A. Birri et al. / Polyhedron 18 (1999) 1825–1833
1827
dissolved in dichloromethane (30 cm3) and an excess of
4-cyanopyridine (0.103 g, 0.36 mmol) added to the
solution. The reaction mixture was stirred for 20 h, then
filtered through celite to remove any undissolved material.
The volume of solution was reduced in vacuo to ca. 10
cm3, and a red solid precipitated. Addition of hexane (10
cm3) to the concentrated solution ensured complete pre-
cipitation. The solid was filtered off and washed with
hexane (20 cm3) and diethylether (40 cm3) and dried in
vacuo. Yield: 0.074 g, 0.18 mmol, 78%. Anal. (Found: C,
40.27, H, 3.86, N, 6.48%. Calc. for RuC14H16Cl2N2S: C,
(m, 1H) (phenyl resonances); d 8.93 (d, 2H); d 8.11 (dd,
2H); d 7.93 (d, 2H), d 7.85 (dd, 2H) ppm (2,29-bypyridyl
resonances). Infrared (KBr): n(PF ), 837 cm21. Mass spec-
trum (positive ion electrospray): 6m/z 681, [M-PF6]1; 649,
[M-PF6-S]1; 541 [M-PF6-TMT]1.
2.2.8. [Ru(h5-C4Me4S)(k3-HBPz3 )][PF6 ] 8
[hRu(h5-C4Me4S)Cl(m-Cl)j2] (0.055 g, 0.09 mmol) was
stirred in H2O (10 cm3) to which Na[HBPz3] (0.046 g,
0.19 mmol) was added. The mixture was stirred for 4 h at
208C, then filtered through celite. The celite was washed
with water and the filtrate and washings combined. The
volume of the solution was reduced to ca. 10 cm3 and this
was treated with an excess of aqueous NH4[PF6]. This
resulted in the immediate formation of a yellow precipitate
which was filtered off and washed with H2O (20 cm3),
CHCl3 (20 cm3) and diethylether (30 cm3), and then dried
in vacuo. Yield: 0.060 g, 0.10 mmol, 57%. Anal.: (Found:
C, 33.61, H, 3.51, N, 13.91%. Calc. for
1
40.39, H, 3.88, N, 6.73%). H NMR [CD2Cl2, 308C]: d
1.85 (br, 6H, TMT); d 1.90 (br, 6H, TMT); d 7.58 (m,
2H,), d 9.20 (br, 2H,) ppm (cyanopyridine resonances).
Infrared (KBr): n(CN), 2235(s) cm21, (Nujol, CsI) n(Ru–Cl)
288(w) cm21. Mass spectrum (positive ion electrospray):
m/z 416, [M]1; 381, [M-Cl]1; 277 [M-Cl-py]1.
2.2.6. [Ru(h5-C4Me4S)(bipy)Cl][PF6 ] 6
1
[hRu(h5-C4Me4S)Cl(m-Cl)j2] (0.112 g, 0.18 mmol) was
stirred in H2O (20 cm3) for ca. 10 min. 2,29-Bipyridine
(0.0583 g, 0.37 mmol) was then added to the aqueous
solution which became a dark orange/red colour. The
mixture was stirred for 10 min then filtered through celite.
The celite was washed with H2O (10 cm3) and the filtrate
and washings combined. Addition of an excess of aqueous
NH4[PF6] resulted in the formation of a yellow precipitate
on cooling in an ice bath. The solid was isolated by
filtration, washed with hexane (30 cm3) and then dried in
vacuo. Yield: 0.149 g, 0.26 mmol, 72%. Anal. (Found: C,
37.62, H, 3.26, N, 4.78, Cl, 6.44%. Calc. for
RuC18H20N2SClPF6: C, 37.40, H, 3.50, N, 4.85, Cl,
6.13%). 1H NMR [(CD3)2CO]: d 2.10 (br s, 12H, TMT); d
7.81 (ddd, 2H) d 8.28 (ddd, 2H) d 8.63 (br dd, 2H), d
9.25 (br, 2H) ppm (2,29-bipyridine resonances). Infrared
RuC17H21N6F6PBS: C, 34.07, H, 3.71, N, 14.05%). H
NMR [(CD3)2CO]: d 2.40 (s, 6H, TMT), d 2.45 (s, 6H,
TMT); d 6.41 (dd, 3H), d 7.98 (d, 3H), d 8.14 (d, 3H)
(pyrazolyl resonances). Infrared (KBr): n(BH), 2502(m);
n(PF), 835(s) cm21. Mass spectrum (FAB): m/z 455
[M-PF6]1.
2.2.9. [Ru2(h5-C4Me4S)2(m-Cl)3 ][PF6 ] 9
[hRu(h5-C4Me4S)Cl(m-Cl)j2] (0.051 g, 0.08 mmol) was
dissolved in H2O (20 cm3) containing an excess of
NH4[PF6]. The solution was stirred for 72 h at room
temperature during which time a red solid was deposited.
This was isolated by filtration and washed with cold water
(10 cm3) and diethylether (50 cm3), and then dried in
vacuo. Yield: 0.043 g, 0.06 mmol, 71%. Anal.: (Found: C,
26.25, H, 3.00, Cl, 14.65%. Calc. for Ru2C16H24Cl3S2PF6:
(Nujol, CsI): n(PF ), 839(s), n(Ru–Cl) 294(w) cm21. Mass
1
C, 26.18, H, 3.30, Cl, 14.49%). NMR: H [(CD3)2CO]: d
6
spectrum (FAB): m/z 433, [M-PF6]1; 398, [M-PF6-Cl]1.
2.10 (s, 12H, TMT), d 2.15 (s, 12H, TMT) ppm. Infrared
(KBr): n(PF 841(vs) cm21. Mass spectrum (FAB): m/z
)
591 [M-PF66]1.
2.2.7. [Ru(h5-C4Me4S)(bipy)(PPhMe2 )][PF6 ]2 7
The compound [Ru(h5-C4Me4S)(bipy)Cl][PF6] (0.040
g, 0.07 mmol) was stirred in H2O (20 cm3) to which was
added Ag[PF6] (0.019 g, 0.07 mmol). The mixture was
stirred for 30 min and then filtered through celite, to
remove the AgCl precipitate that had formed. The celite
was washed with H2O (10 cm3) and the filtrate and the
washings combined. An excess of PPhMe2 (0.05 cm3) was
added to the clear yellow solution and resulted in the
formation of an orange suspension. On cooling in an ice
bath a yellow solid precipitated which was isolated by
filtration, washed with hexane (50 cm3), and dried in
vacuo. Yield: 0.0150 g; 0.02 mmol; 26%. Anal. (Found: C,
37.94, H, 3.61, N, 3.26%. Calc. for RuC26H31N2SP3F12:
C, 37.82, H, 3.79, N, 3.39%). 1H NMR [CD2Cl2]: d 1.85
(d, 6H, 2JPH59.9, P–Me); d 2.04 (br s, 6H, TMT); d 2.06
(br s, 6H, TMT); d 6.58 (m, 2H), d 7.05 (m, 2H), d 7.29
2.3. X-ray crystallography
Crystal and refinement data for compounds 1, 7.CH2Cl2,
8 and 9 are provided in Table 1. For compounds 1, 7, and
8 the data were measured at 293 K on an automated
four-circle diffractometer (Nicolet R3mV) equipped with
graphite monochromated Mo Ka radiation operating at 293
K. The v22u method was used to to measure reflections
in the range 5,2u,508. Three standard reflections were
measured at regular intervals and indicated that none of the
crystals decayed during the experiments. The data were
corrected for Lorentz and polarisation effects and for
absorption, based on additional azimuthal scan data. For 9
crystallographic measurements were recorded at 196 K
with a Nonius Kappa CCD diffractometer equipped with

1828
A. Birri et al. / Polyhedron 18 (1999) 1825–1833
Table 1
Crystal and refinement data for compounds 1, 7–9
1
7?CH2Cl2
8
9
Formula
M
C16H23Cl2PRuS
450.3
C27H33Cl2F12N2P3RuS
910.5
C17H22BF6N6PRuS
599.3
C16H24Cl3F6Ru2S2
733.9
Crystal system
Space group
Monoclinic
Cc
9.380(2)
15.614(3)
13.107(3)
90
100.06(3)
90
1890(1)
4
Orthorhombic
P212121
12.843(3)
12.873(3)
22.869(5)
90
90
90
3781(2)
4
1.600
Monoclinic
P21 /c
11.483(2)
15.130(3)
13.442(3)
90
92.83(3)
90
2332(1)
4
Triclinic
P-1
˚
a/A
10.1369(4)
11.4708(3)
12.7140(5)
114.681(2)
110.547(2)
95.433(2)
1206.2(1)
2
˚
b/A
˚
c/A
a/8
b/8
g/8
3
˚
U/A
Z
Dc /g cm23
1.583
1.707
2.021
F(000)
912
1.30
50
1824
0.82
50
1200
0.90
50
720
1.87
52
m(Mo Ka) mm21
2umax /8
hkl range
Reflections collected
Independant
0–12, 0–20, 217–16
2298
2298
0–15, 0–15, 0–27
3707
3707
0–13, 0–18, 216–15
4287
4074
0–12, 213–13, 216–15
10513
4426
Data/parameters
Goodness of fit on F2
R [I.2s(I)]
2295/189
1.051
3697/434
1.065
4074/298
1.043
4414/272
1.095
0.0254
0.0620
0.0290
0.0869
0.476
20.808
R150.0220
wR250.0555
R150.0235
wR250.0607
0.65
0.0665
0.1449
0.1332
0.2137
1.023
0.0391
0.1000
0.0530
0.1204
0.745
R (all data)
DF synthesis
(max, min e A
23
˚
)
20.48
20.754
20.471
graphite monochromated Mo Ka radiation using w rota-
tions with 28 frames and a detector to crystal distance of 25
mm. Integration was carried out by the program DENZO-
SMN [33]. Data were corrected for Lorentz and polariza-
tion effects, and for the effects of absorption using the
program SCALEPACK [33].
Structures were solved by direct methods (SHELXS-86)
[34] developed using alternating cycles of least-squares
refinement and difference Fourier synthesis (SHELX-93)
[35]. All non-hydrogen atoms were refined anisotropically
whilst the hydrogen atoms were fixed in idealised positions
and allowed to ride on the atom to which they were
attached. During the latter stages of the refinement of 7 the
presence of a solvent of crystallisation became apparent.
This was successfully modelled as dichloromethane. Se-
lected geometrical parameters are reported in Tables 2–5.
Table 3
Selected bond lengths (A) and angles (8) for [Ru(h5-C4Me4S)
˚
Table 2
(bipy)(PPhMe2)][PF6]2?CH2Cl2 7
Selected bond lengths (A) and angles (8) for [Ru(h5-
˚
Lengths
C4Me4S)Cl2(PPhMe2)] 1
Ru(1)–C(1)
Ru(1)–C(2)
Ru(1)–C(3)
Ru(1)–C(4)
S(1)–C(1)
C(2)–C(3)
S(1)–C(4)
P(1)–C(31)
2.27(2)
2.26(2)
2.28(2)
2.20(2)
1.77(2)
1.49(2)
1.76(2)
1.82(2)
Ru(1)–S(1)
Ru(1)–P(1)
Ru(1)–N(1)
Ru(1)–N(2)
C(1)–C(2)
C(3)–C(4)
P(1)–C(21)
P(1)–C(41)
2.397(5)
2.364(4)
2.089(14)
2.091(14)
1.40(2)
1.44(3)
1.82(2)
1.83(2)
Lengths
Ru(1)–C(1)
Ru(1)–C(2)
Ru(1)–C(3)
Ru(1)–C(4)
S(1)–C(1)
C(2)–C(3)
S(1)–C(4)
P(1)–C(10)
2.158(4)
2.221(4)
2.228(4)
2.169(4)
1.799(4)
1.444(7)
1.790(5)
1.854(4)
Ru(1)–S(1)
Ru(1)–P(1)
Ru(1)–Cl(1)
Ru(1)–Cl(2)
C(1)–C(2)
C(3)–C(4)
P(1)–C(9)
2.4422(12)
2.3303(10)
2.4414(11)
2.4419(11)
1.427(7)
1.425(7)
1.835(4)
1.842(4)
P(1)–C(11)
Angles
N(1)–Ru(1)–N(2)
N(2)–Ru(1)–P(1)
S(1)–C(1)–C(2)
C(2)–C(3)–C(4)
Ru(1)–N(1)–C(11)
Ru(1)–N(2)–C(20)
77.4(5)
89.7(4)
112.3(13)
110(2)
125.7(14)
124.5(12)
N(1)–Ru(1)–P(1)
C(1)–S(1)–C(4)
C(1)–C(2)–C(3)
C(3)–C(4)–S(1)
Ru(1)–N(1)–C(15)
Ru(1)–N(2)–C(16)
87.4(4)
91.8(8)
113(2)
112.6(10)
115.5(12)
117.7(11)
Angles
Cl(1)–Ru(1)–Cl(2)
Cl(2)–Ru(1)–P(1)
S(1)–C(1)–C(2)
C(2)–C(3)–C(4)
90.82(4)
83.17(4)
110.9(3)
112.5(4)
Cl(1)–Ru(1)–P(1)
C(1)–S(1)–C(4)
C(1)–C(2)–C(3)
C(3)–C(4)–S(1)
86.84(4)
90.3(2)
112.9(4)
111.5(4)

A. Birri et al. / Polyhedron 18 (1999) 1825–1833
1829
Table 4
bond due to significant steric interaction with the sub-
stituents on the thiophene ring such that each methyl is
rendered unique [21]. We were interested to probe whether
mixed alkyl/aryl phosphine ligands also gave rise to
significant interactions and to that end prepared the com-
pound [Ru(h5-C4Me4S)Cl2(PPhMe2)] 1 by the reaction of
[hRu(h5-C4Me4S)Cl(m-Cl)j2] with PPhMe2 in dichlorome-
thane. In the room temperature 1H NMR spectrum the
methyl signals on the thiophene ligands appear as two
widely spaced broad singlets, d 1.30 and 1.88 ppm. On
lowering the temperature of the NMR probe to 2608C the
signals sharpen, d 1.28 and 1.87 ppm, but no splitting
occurs, indicating that even at this temperature the rotation
of both the phosphine and thiophene ligands is rapid. As
no [Ru(h5-C4Me4S)Cl2(PR3)] compound had been previ-
ously characterised by X-ray diffraction we decided to
undertake such a study on 1, Fig. 1. If we assume the
thiophene ligand to coordinate as a tridentate diolefin–
thioether ligand then we can see that this ligand occupies
three facial sites on an octahedral ruthenium(II) ion. The
only previously reported X-ray structure of a simple
[Ru(h5-C4Me4S)L3] compound was that of [Ru(h5-
C4Me4S)(H2O)3][OTf]2, which was severely disordered
[22]. The thiophene ligand in 1 is approximately planar.
5
3
˚
Selected bond lengths (A) and angles (8) for [Ru(h -C4Me4S)hk -
HB(Pz)3j][PF6] 8
Lengths
Ru(1)–C(1)
Ru(1)–C(3)
Ru(1)–C(5)
Ru(1)–C(7)
S(1)–C(1)
C(3)–C(5)
S(1)–C(7)
2.184(4)
2.240(4)
2.245(4)
2.204(4)
1.795(5)
1.464(7)
1.800(5)
Ru(1)–S(1)
Ru(1)–N(12)
Ru(1)–N(22)
Ru(1)–N(32)
C(1)–C(3)
2.4006(12)
2.151(4)
2.159(4)
2.125(3)
1.419(6)
1.415(7)
C(5)–C(7)
Angles
N(12)–Ru(1)–N(22) 82.94(14) N(12)–Ru(1)–N(32) 84.51(14)
N(22)–Ru(1)–N(32) 85.21(14) C(1)–S(1)–C(7)
S(1)–C(1)–C(3)
C(3)–C(5)–C(7)
Ru(1)–N(12)–N(11) 120.0(3)
Ru(1)–N(32)–N(31) 120.3(3)
90.2(2)
112.0(4)
111.9(4)
112.4(3)
112.9(4)
C(1)–C(3)–C(5)
C(5)–C(7)–S(1)
Ru(1)–N(22)–N(21) 120.3(3)
N(11)–B(1)–N(21)
N(21)–B(1)–N(31)
108.0(4)
108.1(4)
N(11)–B(1)–N(31)
107.9(4)
3. Results and discussion
few compounds of the type [Ru(h5-
Only
a
C4Me4S)Cl2L] have been reported previously. Notable
among these are the [Ru(h5-C4Me4S)Cl2(PR3)] [21] (R5
Me, Bu, Ph, p-tolyl) series of compounds. While the
trialkylphosphine derivatives have unremarkable NMR
spectra the variable temperature spectra of the triarylphos-
phine compounds are interesting. In particular at low
temperature the TMT ligand exhibits four methyl reso-
nances consistent with hindered rotation about the Ru–P
˚
However the sulfur atom is displaced 0.27 A out of the
plane formed by the atoms C(1), C(2), C(3), and C(4) on
the side away from the metal. This slight folding of the
ligand is also apparent in the angle of 12.58 formed
between the planes [C(1)S(1)C(4)] and [C(1)
C(2)C(3)C(4)]. Further distortions from planarity are
observed for the methyl substituents on the thiophene
which are displaced somewhat from the metal, with
deviations ranging from 6.1 to 7.58. Although inspection of
the C–C bond lengths implies some localisation of the
olefinic bonds the differences are not statistically signifi-
cant in this structure. The Ru–C bond lengths form two
pairs with those to the carbons adjacent to sulfur sig-
Table 5
5
˚
Selected bond lengths (A) and angles (8) for [Ru2(h -C4Me4S)2(m-
Cl)3][PF6] 9
Lengths
Ru(1)–Cl(1)
Ru(1)–Cl(2)
Ru(1)–Cl(3)
Ru(1)–S(1)
Ru(1)–C(1)
Ru(1)–C(2)
Ru(1)–C(3)
Ru(1)–C(4)
S(1)–C(1)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–S(1)
2.4792(7)
2.4615(7)
2.4167(7)
2.3375(7)
2.117(3)
2.170(3)
2.155(3)
2.116(3)
1.770(3)
1.420(4)
1.437(4)
1.418(4)
1.766(3)
Ru(2)–Cl(1)
Ru(2)–Cl(2)
Ru(2)–Cl(3)
Ru(2)–S(2)
Ru(2)–C(9)
Ru(2)–C(10)
Ru(2)–C(11)
Ru(2)–C(12)
S(2)–C(9)
C(9)–C(10)
C(10)–C(11)
C(11)–C(12)
C(12)–S(2)
2.4160(7)
2.4600(7)
2.4752(7)
2.3353(7)
2.114(3)
2.153(3)
2.172(3)
2.133(3)
1.773(3)
1.414(4)
1.441(4)
1.420(4)
1.764(3)
˚
nificantly shorter, average 2.163(4) A, than those to the
Angles
Cl(1)–Ru(1)–Cl(2)
Cl(2)–Ru(1)–Cl(3)
Cl(1)–Ru(1)–Cl(3)
Ru(1)–Cl(1)–Ru(2)
Ru(1)–Cl(3)–Ru(2)
C(1)–S(1)–C(4)
S(1)–C(1)–C(2)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–S(1)
80.73(2)
80.93(2)
80.29(2)
83.39(2)
83.46(2)
90.96(14)
111.6(2)
112.2(2)
112.7(2)
111.6(2)
Cl(1)–Ru(2)–Cl(2)
Cl(2)–Ru(2)–Cl(3)
Cl(1)–Ru(2)–Cl(3)
Ru(1)–Cl(2)–Ru(2)
C(9)–S(2)–C(12)
S(2)–C(9)–C(10)
C(9)–C(10)–C(11)
C(10)–C(11)–C(12)
C(11)–C(12)–S(2)
82.03(2)
79.81(2)
80.39(2)
82.86(2)
91.30(14)
111.0(2)
113.3(3)
111.9(3)
111.8(2)
Fig. 1. The crystal structure of [Ru(h5-C4Me4S)Cl2(PPhMe2)] 1, show-
ing the atom labelling scheme.

1830
A. Birri et al. / Polyhedron 18 (1999) 1825–1833
˚
other two carbon atoms, average 2.224(4) A. The Ru–S
resonances are sharp and give rise to the eight-line pattern
expected for an AA9BB9 spin system, chemical shifts d
7.54, 7.64, 8.80 and 9.24 ppm. At the same time the
thiophene methyls appear as four singlets, d 1.50, 1.97,
2.01 and 2.02 ppm. Clearly for 5 at low temperature in
solution we have frozen out a structure in which each
methyl is unique. Whether this arises due to restricted
rotation about the Ru–N bond, or restricted rotation of the
tetramethylthiophene ligand, or both, is unclear. However,
as Rauchfuss pointed out in his discussion of the NMR
spectrum of [Ru(h5-C4Me4S)Cl2(PPh3)] inhibiting rota-
tion about one Ru–ligand bond can be sufficient to render
each methyl unique if the ‘rotamer’ stabilised at low
temperature has the unique ligand, in our case 4-
cyanopyridine, placed such that its projection bisects a
S–C bond [21].
˚
bond, 2.442(1) A, is considerably longer than those
observed in [Ru(h -C4Me4S)(H2O)3][OTf]2, 2.307(6) A
[22], or [Ru(h -C4Me4S)2][BF4]2, average 2.355(2) A
5
˚
5
˚
[21], but rather more comparable to those observed in the
polynuclear compound [hRu(h5-C4Me4S)(m-Cl)j3(m3-S)],
˚
2.414(4)–2.432(4) A [21]. The structure can be compared
to that of the related isoelectronic Ru(arene) derivative
[Ru(h6-p-cymene)Cl2(PPhMe2)] [36], and indeed with
around ten other crystal structures of [Ru(h6-arene)
Cl2(PR3)] compounds [37–43] documented on the Cam-
bridge Crystallographic database. Interestingly, while the
Ru–P bond length in this compound, 2.330(1) A, does not
differ greatly from the average, 2.357 A (range 2.291–
2.379 A), found for [Ru(h -arene)Cl2(PR3)] compounds
the Ru–Cl bonds for 1, 2.441(1) A, are considerably
˚
˚
6
˚
˚
In addition to simple bridge cleavage reactions it is
possible to prepare compounds in which one or more of
the chloride ligands have been displaced from the metal
centre. Rauchfuss used silver reagents to remove the
halides from [hRu(h5-C4Me4S)Cl(m-Cl)j2], in the prepara-
tion of [Ru(h5-C4Me4S)2][BF4]2 [21] and [Ru(h5-
C4Me4S)(OTf)2]n [22], however, we report here that for
some ligands at least the use of the expensive silver
reagent is unnecessary.
longer than those observed in the Ru(arene) analogues,
˚
˚
average 2.406 A (range 2.381–2.425 A).
The reaction of [hRu(h5-C4Me4S)Cl(m-Cl)j2] with
P(OCH3)3 gives an analogous compound to 1, namely
[Ru(h5-C4Me4S)Cl2(P(OCH3)3)] 2. Given the small cone
angle for this phosphite ligand one would anticipate that
1
the H NMR spectrum would be essentially invariant with
temperature and indeed the spectrum remains unchanged in
the range 260 to 08C, with only two tetramethylthiophene
methyl resonances observed throughout, d 1.98 and 2.00
ppm. At 208C the two singlets are unresolved, appearing as
a symmetrical singlet, but we attribute that to accidental
coincidence of the chemical shifts, which vary slightly
with temperature in any case, rather than some dynamic
Aqueous solutions of [hRu(h5-C4Me4S)Cl(m-Cl)j2]
react rapidly with 2,29-bipyridine. When the reaction time
is in excess of 30 min addition of NH4[PF6] to the reaction
mixture gives the well-known [Ru(bipy)3][PF6]2 as the
only isolated product. However, if the reaction time is
limited to a maximum of 15 min, and the work up is
process.
C4Me4S)Cl(m-Cl)j2] reacts with carbon monoxide to give
yellow insoluble precipitate of
[Ru(h5-
A
dichloromethane solution of [hRu(h5-
performed
rapidly
then
the
complex
[Ru(h5-
C4Me4S)Cl(bipy)][PF6] 6 is obtained in good yield.
Although the solid is stable, solutions of 6 rapidly de-
compose. The proton resonances for the thiophene methyl
groups are not resolved for this compound and appear as a
broad singlet at ambient temperature. However, the four
anticipated resonances for the aromatic protons of the
2,29-bipyridine ligand are clearly seen and integration of
the spectrum confirms the ligand stoichiometry. The
highest peak in the FAB mass spectrum corresponds to the
[Ru(h5-C4Me4S)Cl(bipy)]1 ion and the sequential loss of
chloride from this is observed (see Section 2). Compound
6 will react further with PPhMe2 /Ag[PF6] to give [Ru(h5-
C4Me4S)(bipy)(PPhMe2)][PF6]2 7, albeit in only modest
yield. The spectroscopic characterisation of 7 was routine,
a
C4Me4S)Cl2(CO)] 3. The positive ion electrospray mass
spectrum of this compound exhibits a parent ion peak, at
m/z 340, and shows fragmentation peaks due to the loss of
chloride and CO (see Section 2). The infrared spectrum of
3 contains a n(CO) band at 1982 cm21, compared to one of
2054 cm21 reported for [Ru(h5-C4Me4S)(OTf)2(CO)]
[22]. The reaction of [hRu(h5-C4Me4S)Cl(m-Cl)j2] with
pyridine gives [Ru(h5-C4Me4S)Cl2(NC5H5)] 4 which has
1
been routinely characterised (see Section 2). The H NMR
spectrum recorded at 208C in CD2Cl2 exhibits two rather
broad thiophene methyl resonances, at d 1.81 and 1.88
ppm, as well as the usual three signals for the pyridine
ligand. On cooling to 08C the methyl signals become
degenerate, and further cooling results in the precipitation
of the compound from solution and no useful spectra could
be obtained. In contrast if one prepares the 4-
cyanopyridine analogue [Ru(h5-C4Me4S)Cl2(NC5H4CN)]
5 NMR measurements can be made over a wide tempera-
ture range. At 308C in CD2Cl2 the NMR spectrum consist
of a pair of broad methyl resonances, at d 1.85 and 1.90
ppm, and two broad signals, at d 7.57 and 9.21 ppm, due
to the protons on the pyridyl ring. On cooling to 2808C
the spectrum changes dramatically, such that the pyridyl
1
with integration of the H NMR spectrum being consistent
with a 1:1:1 ratio of the ligands C4Me4S, bipy, and
PPhMe2. Confirmation of the identity of 7 was obtained by
X-ray structure determination, Fig. 2. Unfortunately the
crystal used in this study was significantly poorer than that
employed for the other three structure determinations
reported herein (only ca. 60% of the measured reflections
were observed at the 2s(I) level). Hence, the lower
precision in the reported geometrical parameters, precludes
a detailed discussion of the structure. Nevertheless, the

A. Birri et al. / Polyhedron 18 (1999) 1825–1833
1831
solutions of Na[HB(Pz)3] react smoothly with [hRu(h5-
C4Me4S)Cl(m-Cl)j2] to give a yellow solution from which
[Ru(h5-C4Me4S)(k3-HBPz3)][PF6] 8 can be precipitated
by the addition of NH4[PF6]. The infrared spectrum of this
material exhibits typical n(BH) and n(PF) bands, at 2052 and
1
835 cm21, respectively. The H NMR spectrum consists of
the three pyrazolyl resonances, d 8.14, 7.98, and 6.41 ppm,
two methyl resonances from the thiophene ligand, d 2.45
and 2.40 ppm, and a rather broad signal at ca. 4.2 ppm, due
to the proton on boron. Complete confirmation of the
structure of 8 is obtained by a single crystal structure
determination, Fig. 3. The basic geometry is as described
previously with pseudo-octahedral coordination at
ruthenium, though it should be noted that the angles
subtended at ruthenium are somewhat smaller than in the
two previous compounds, 83–858, as a consequence of the
chelate bite of the hydridotris(pyrazolyl)borate ligand.
While the thiophene ligand can be described as approxi-
mately planar there are nevertheless deviations from
planarity similar to those described for 1. In general,
however, these deviations are somewhat smaller than
Fig. 2. The crystal structure of the cation in [Ru(h5-C4Me4S)
(bipy)(PPhMe2)][PF6]2 7, showing the atom labelling scheme.
diffraction experiment clearly demonstrates the octahedral
coordination at the metal. We also note that the thiophene
ring is closer to planarity than was observed to be the case
for 1, and interestingly while the Ru–P distance, 2.364(4)
˚
before. For example, the sulfur is displaced by 0.15 A from
the plane of the metallated carbons on the side away from
the metal and the folding of the thiophene ligand is 7.18,
cf. 12.58 for 1. The Ru–C bonds again form a long and a
short pair, however the average Ru–C distance in 8,
˚
A, is somewhat longer than that observed for 1 the Ru–S
˚
distance, 2.397(5) A, is markedly shorter, by some 0.045
˚
˚
2.218(4) A, is significantly longer than that for 1, 2.194(4)
A. Finally it should be noted that while ‘Ru(arene)’
˚
A, reflecting the superior sigma donor power of the N3
analogues of 6 and 7 have been described [44] none of
these have been crystallographically characterised.
ligand set in 8, which is also reflected in the shorter Ru–S
By studying the reaction of [hRu(h5-C4Me4S)Cl(m-
Cl)j2] with Na[HB(Pz)3] we have established that all the
chlorides can be removed from the metal, while the
thiophene ligand is retained, in a single synthetic step.
Initially we attempted this reaction in a variety of organic
solvents, however yields were invariably low. Indeed the
optimum solvent for this, and a number of other reactions,
would, rather surprisingly, appear to be water. Aqueous
˚
distance, 2.401(1) A. The Ru–N distances can be usefully
compared to those observed for the analogous Ru(arene)
compound, [Ru( p-cymene)hHB(Pz)3j][PF6] [45]. As with
[Ru( p-cymene)hHB(Pz)3j][PF6] the Ru–N distances are
˚
unequal, with two longer, 2.151(4) and 2.159(4) A, and
˚
one shorter, 2.125(3) A, bond. Each of these bonds is
˚
approximately 0.03 A longer in 8 reflecting the greater
trans influence of the thiophene ligand and which is
consistent with the fact that [hRu(h5-C4Me4S)Cl(m-Cl)j2]
is prepared from [hRu(h6-p-cymene)Cl(m-Cl)j2] via an
arene displacement reaction.
It will have been noticed that many of the reactions
described above have been performed in aqueous solution.
Rauchfuss originally examined the behaviour of [hRu(h5-
C4Me4S)Cl(m-Cl)j2] in aqueous solution by 1H NMR
spectroscopy [21]. He reported that in D2O two species
were present in an approximate ratio of 10:1. The minor
species
was
identified
as
the
ion
[Ru(h5-
C4Me4S)(D2O)3]21 which could be synthesised indepen-
dantly, isolated as its triflate salt, and characterised by
X-ray diffraction [22]. At the time of the original report the
major component was not identified. Given our success in
synthesising new compounds in aqueous solution we
thought it important to re-examine this reaction. When
[hRu(h5-C4Me4S)Cl(m-Cl)j2] is placed in an aqueous
solution containing an excess of NH4[PF6] a red solid
Fig. 3. The crystal structure of the cation in [Ru(h5-C4Me4S)(k3-
HBPz3)][PF6] 8, showing the atom labelling scheme.
1
deposits from solution over a period of 72 h. The H NMR

1832
A. Birri et al. / Polyhedron 18 (1999) 1825–1833
spectrum of that compound exhibits only one set of
tetramethylthiophene signals, d 2.15 and 2.10 ppm. A
simple test with HNO3 /AgNO3 reveals that the compound
still contains chloride ions. The mass spectrum exhibits a
peak at m/z 591 which displays the predicted isotope
pattern for two ruthenium and three chlorine atoms. This
data together with the elemental analysis (see Section 2)
suggest that the compound be formulated as [Ru2(h5-
C4Me4S)2(m-Cl)3][PF6] 9, which was subsequently con-
firmed by X-ray diffraction, Fig. 4. The complex cation has
thiophene complexes of ruthenium(II) has focused on the
reactivity of the metallated ligand, we have demonstrated
that there is considerable scope for developing the coordi-
nation chemistry of the Ru(h5-thiophene) moiety, perhaps
into such areas as bio-organometallic chemistry and water
soluble catalysts.
Supplementary data
a
face-sharing bi-octahedral structure with the two
ruthenium(II) ions bridged unsymmetrically by three chlo-
ride ions. There are four long Ru–Cl distances, 2.4600(7)–
Supplementary data are available from the CCDC, 12
Union Road, Cambridge CB2 1EZ, UK on request, quoting
the deposition numbers CCDC 112384–112387.
˚
˚
2.4792 A, and two short, 2.4168(7) and 2.4160(7) A.
The short bonds are approximately trans to the Ru–S
bonds, S(1)–Ru(1)–Cl(3) 167.58(3)8, S(2)–Ru(2)–Cl(1)
167.24(3)8, and reflect the trans influence of the ligating
sulfur atoms, which form shorter bonds to the metal,
Acknowledgements
˚
2.3375(7) and 2.3353(7) A, than seen in the other com-
We would like to thank Johnson Matthey plc. for
generous loans of ruthenium trichloride, the EPSRC for
financial support (AB), King’s College London and the
EPSRC for funding the diffractometer system, and the
Nuffield Foundation for the provision of computing equip-
ment.
pounds we have investigated. Nevertheless, the sulfur
˚
˚
atoms are still displaced, 0.18 A S(1) and 0.17 A S(2),
from the plane of the four metallated carbon atoms of the
thiophene ligand on the side away from the metal. Despite
the wide range of Ru–Cl distances the mean value,
˚
2.4514(7) A, is not very different from the mean value
observed for the analogous [Ru2(h6-arene)2(m-Cl)3]1 cat-
˚
ions reported in the literature, 2.430 A [46–50]. The angles
Cl–Ru–Cl subtended at ruthenium are 80(61)8, while the
angles at the bridging chlorides are 83(61)8. These values
are unremarkable and fall within the normal range for
compounds in which three halide ions bridge two metal
centres in the absence of any metal–metal bond. Although
it might seem unlikely that 9 be formed in aqueous
solution, its preparation closely mimics that of [Ru2(h6-
C6H6)2(m-Cl)3][PF6], which can be obtained in low yield
by stirring [hRu(h6-C6H6)Cl(m-Cl)j2] in an aqueous solu-
tion of NH4[PF6] [51], or in higher yield by using a
methanolic solution [52].
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