Photochemical synthesis of ruthenium-carbonyl compounds with thioether ligands and subsequent oxidative cleavage of trinuclear complexes by chlorinated solvents

Article abstract of DOI:10.1002/ejic.201000862

The photochemical reaction of [Ru₃(CO)₁₂] with thioether ligands in THF leads to the isolation of tetranuclear ruthenium-carbonyl cluster compounds of the formula [Ru₄(CO) ₁₃(μ₂-R₂S)]. In these compounds, ruthenium atoms adopt a typical butterfly arrangement. If chelating ligands with two thioether functions are introduced, the reaction leads to mixtures of the trinuclear substitution products [Ru₃(CO)₁₀(RSSR)] and [Ru₃(CO)₈(RSSR)₂]. The latter may be oxidatively cleaved by the use of chlorinated solvents to produce the mononuclear compound [Ru(CO)₂Cl₂(RSSR)] or the dinuclear complex [Ru₂(CO)₂(μ₂-Cl)₂Cl ₂(RSSR)₂] depending on the reaction conditions. Five new ruthenium-carbonyl-thioether complexes were characterized by X-ray diffraction. Irradiation of [Ru₃(CO)₁₂] in THF in the presence of thioether ligands yields ruthenium-carbonyl compounds [Ru₄(CO) ₁₃(μ₂-R₂S)] in the case of monodentate ligands, but [Ru₃(CO)₁₀(RSSR)] and [Ru₃(CO) ₈(RSSR)₂] if bidentate thioether ligands are used. The latter may be oxidatively cleaved by CHCl₃ to produce the dinuclear complex [Ru₂(CO)₂(μ₂-Cl)₂Cl ₂(RSSR)₂]. Copyright

Full text of DOI:10.1002/ejic.201000862

FULL PAPER
DOI: 10.1002/ejic.201000862
Photochemical Synthesis of Ruthenium–Carbonyl Compounds with Thioether
Ligands and Subsequent Oxidative Cleavage of Trinuclear Complexes by
Chlorinated Solvents
Biplab K. Maiti,[a] Helmar Görls,[a] Olaf Klobes,[b] and Wolfgang Imhof*[a]
Keywords: Ruthenium / Carbonyl ligands / Thioether ligands / Photochemistry / X-ray diffraction
The photochemical reaction of [Ru3(CO)12] with thioether li-
gands in THF leads to the isolation of tetranuclear ruthe-
and [Ru3(CO)8(RSʝSR)2]. The latter may be oxidatively
cleaved by the use of chlorinated solvents to produce the mo-
nonuclear compound [Ru(CO)2Cl2(RSʝSR)] or the dinuclear
complex [Ru2(CO)2(μ2-Cl)2Cl2(RSʝSR)2] depending on the
reaction conditions. Five new ruthenium–carbonyl–thioether
complexes were characterized by X-ray diffraction.
nium–carbonyl cluster compounds of the formula [Ru4(CO)13
-
(μ2-R2S)]. In these compounds, ruthenium atoms adopt a typi-
cal butterfly arrangement. If chelating ligands with two thio-
ether functions are introduced, the reaction leads to mixtures
of the trinuclear substitution products [Ru3(CO)10(RSʝSR)]
bridge two or more transition metal atoms are much less
common than sulfide- or thiolate-bridged compounds. We
recently published a report about the synthesis of ruthe-
nium–carbonyl complexes with thioether ligands from the
reaction of [Ru3(CO)12] with the respective thioethers under
irradiation in chloroform.[6] Most interestingly, we observed
reaction pathways in which ruthenium atoms are oxidized
to the oxidation state II with chlorido ligands that originate
from solvent molecules balancing the positive charge.
Herein we present results of photochemical reactions of
[Ru3(CO)12] with the same thioether ligands under irradia-
tion in THF. Correspondingly, no redox reaction pathways
are observed. Depending on the thioether used and reaction
conditions, tri- or tetranuclear ruthenium–carbonyl cluster
compounds are isolated. Upon dissolving the compounds
in chloroform, the former are transferred into the mononu-
clear RuII complexes observed before.[6]
Introduction
Quite recently, we became interested in the chemistry of
thioether ligands in the coordination sphere of ruthenium
due to research activities in the field of catalytic transfor-
mations of thioethers. Thioethers as well as hydrogen sul-
fide, thiols, and thiophenes naturally appear in fossil fuels
due to the anaerobic degradation of sulfur-containing bio-
logical material such as cysteine and methionine residues in
proteins.[1] They are undesirable in this respect since they
tend to poison catalysts used in fuel processing as well as
in exhaust gas treatment and must therefore be removed
producing desulfurized fuel.[2] On the other hand, poly-
sulfides are widely used as sealing compounds (e.g., for the
production of multiply glazed windows, kerosene tanks of
aircrafts, or the ground beneath gas stations). In this con-
text, ruthenium precatalysts that already exhibit thioether
ligands seem to be less prone to being poisoned by ad-
ditional sulfur-containing substrates. Complexes of this
type have, for example, been used for the synthesis of sulf-
oxides from thioethers.[3]
Results and Discussion
Scheme 1 shows the reaction of [Ru3(CO)12] with tetra-
Thioethers in general prefer monodentate coordination hydrothiophene (THT) and 1,4-oxathiane (OXT) in THF
modes if bound to transition metals.[4] Nevertheless, in under irradiation with UV light. After approximately
some cases insertion reactions of metal atoms or nucleo- 20 min, the formation of an insoluble precipitate is ob-
philes in general into carbon–sulfur bonds have also been served. So the reaction time was limited to 40 min. After
observed.[5] Moreover, compounds in which thioethers filtration of the precipitate and chromatographic workup,
tetranuclear ruthenium cluster compounds 1a and 1b were
isolated in low yields. Compounds 1a and 1b were analyzed
by mass spectrometry and IR and H NMR spectroscopy.
[a] Institute of Inorganic and Analytical Chemistry, Friedrich
Schiller University Jena,
1
August-Bebel-Strasse 2, 07743 Jena, Germany
Fax: +49-3641-948102
Mass spectrosopy showed the tetranuclear composition of
the compounds, and from IR spectroscopy it became evi-
dent that next to terminal CO ligands there are also bridg-
E-mail: Wolfgang.Imhof@uni-jena.de
[b] Akzo Nobel Functional Chemicals GmbH & Co. KG,
Liebigstrasse 7, 07973 Greiz, Germany
Fax: +49-3661-78219
1
ing CO groups present. H NMR spectra showed signals
E-mail: Olaf.Klobes@akzonobel.com
that represent methylene units at expected chemical shifts.
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B. K. Maiti, H. Görls, O. Klobes, W. Imhof
FULL PAPER
Scheme 1. Photochemical reaction of [Ru3(CO)12] with heterocyclic thioethers in THF.
By recrystallization from mixtures of light petroleum and bridging CO ligand is always significantly shorter than the
THF at 0 °C, it was possible to obtain single crystals of 1a other Ru–C bond (isomer 1: Ru3a–C14a 201.0 pm, Ru4a–
and 1b. The molecular structures of two isomers of 1a are C14a 231.0 pm; isomer 2: Ru3b–C14b 233.4 pm, Ru4b–
depicted in Figure 1; Figure 2 correspondingly shows the C14b 201.4 pm). The molecular structure of 1b closely re-
structure of 1b. Selected bond lengths and angles are sum- sembles the situation in isomer 2 of 1a (Figure 2, Table 1).
marized in Table 1. In the crystal structure of 1a, two iso-
Only a few similar tetranuclear ruthenium compounds
meric cluster compounds are observed that differ signifi- with bridging thioether ligands that use trithiane, 3,3-di-
cantly with regards to the arrangement of the ruthenium methylthietane, dimethyl sulfide, or even THT as ligands
centers, coordination of one CO ligand, and ruthenium– have been reported before.[7] These ligands are either coor-
sulfur bond lengths. Nevertheless, most of the other bond- dinated to an [Ru4(CO)13] fragment as in 1a and 1b or to
ing properties remain unchanged. In both compounds four an [Ru4(CO)12(μ2-H)2] fragment. There is one crystal struc-
ruthenium atoms are observed in a butterfly arrangement. ture of 1a described before that is almost isostructural.[7d]
The dihedral angle between the two Ru3 planes are 95.3° Although the same structural dissimilarities between two
in isomer 1 (Figure 1, top) and 84.6° in isomer 2 (Figure 1, independent molecules are also observed, they are not dis-
bottom). The sulfur atoms of THT ligands bridge two of cussed by the authors. Moreover, their structural analysis
the ruthenium atoms, with the ruthenium–sulfur bonds be- was performed at room temperature and R values therefore
ing slightly different. In both isomers one of the CO ligands are slightly worse than those of 1a described herein.
is slightly bent (isomer 1: Ru3a–C11a–O7a 159.0°; isomer 2:
According to IR spectroscopy, the precipitates that are
Ru4b–C15b–O11b 162.4°) with the corresponding carbon produced during the synthesis of 1a and 1b are also ruthe-
atom being situated quite close to another Ru atom (iso- nium–carbonyl species. Although bands that correspond to
mer 1: Ru2a–C11a 256.3 pm; isomer 2: Ru1b–C15b the sulfur-containing ligands in 1a and 1b are much weaker,
266.2 pm). The additionally coordinated Ru2a shows the elemental analyses still showed that the precipitates contain
longest Ru–S bond [239.55(8) pm]. The central Ru–Ru sulfur. Nevertheless, hydrogen contents indicate that there
bond of the tetranuclear cluster is bridged by another car- should be other organic ligands in addition to THT or
bon monoxide ligand. However, this ligand also is not sym- OXT. We therefore propose that the precipitates are poly-
metrically bound, but the bond towards the ruthenium mers that exhibit thioether as well as THF ligands that at
atom that is coordinated by the above-mentioned semi- least partly bridge ruthenium atoms as in 1a and 1b. The
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Photochemical Synthesis of Ruthenium–Carbonyl Compounds
Figure 2. Molecular structure of 1b.
tographic workup, two ruthenium cluster compounds 3 and
4 were obtained in moderate yields. According to their IR
and mass spectra, it became evident that both compounds
represent trinuclear ruthenium complexes with one (3) and
two (4) C2S2 moieties present in the molecules next to ter-
minal as well as bridging CO ligands. Crystal-structure
analyses of both 3 and 4 confirmed that both compounds
are most probably produced from [Ru3(CO)12] just by sub-
stitution of two or four CO ligands without any decomposi-
tion of the trinuclear cluster core. This is also most proba-
bly the reason why no formation of a precipitate was ob-
served in this case. During the formation of tetranuclear
compounds 1 from the trinuclear starting material, cluster
degradation and aggregation processes must have taken
place, therefore also triggering the formation of polynuclear
material.
Figure 1. Molecular structures of two isomers of 1a.
precipitates of both reactions were transformed into the
mononuclear ruthenium complex [Ru(CO)3(PPh3)2] (2) by
stirring a suspension of the polymer in THF in the presence
of an excess amount of triphenylphosphane at room tem-
perature for 6 d. Probably the stronger Lewis base PPh3 was
able to cleave thioether and THF bridges in the polymer.
The identity of 2 is shown by a comparison of its experi-
mental data with that already published in the literature.[8]
Scheme 2 shows the photochemical reaction of [Ru3-
(CO)12] with the chelating ligand C2S2 under reaction con-
ditions already described for the synthesis of 1a and 1b. In
contrast to the reaction with monodentate thioether li-
Scheme 2. Photochemical reaction of [Ru3(CO)12] with chelating
gands, no insoluble precipitate was formed. After chroma- C2S2 in THF.
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B. K. Maiti, H. Görls, O. Klobes, W. Imhof
FULL PAPER
Table 1. Bond lengths [pm] and angles [°] of 1a and 1b.
C distances. In contrast, the second bridging CO ligand ex-
hibits Ru–C contacts that show a difference of almost
30 pm. Nevertheless, in both ligands the shorter Ru–C bond
is always the one towards Ru1 and is in a trans position
with respect to the coordinating sulfur atoms.
Complex 1a (isomer 1)
Ru1a–Ru3a
Ru2a–Ru3a
Ru3a–Ru4a
Ru2a–S1a
Ru2a–C11a
Ru4a–C14a
285.75(3) Ru1a–Ru4a
281.70(3) Ru2a–Ru4a
279.02(3) Ru1a–S1a
239.55(8) Ru3a–C11a
280.88(3)
286.84(3)
237.95(7)
194.6(3)
201.0(3)
256.3(3)
231.0(3)
Ru3a–C14a
Ru3a–Ru1a–Ru4a 58.992(8) Ru1a–Ru3a–Ru4a 59.632(8)
Ru1a–Ru4a–Ru3a 61.376(8) Ru3a–Ru2a–Ru4a 58.774(8)
Ru2a–Ru3a–Ru4a 61.534(8) Ru2a–Ru4a–Ru3a 59.692(8)
Ru1a–Ru3a–Ru2a 80.161(9) Ru1a–Ru4a–Ru2a 80.111(9)
Ru1a–S1a–Ru2a
Ru2a–S1a–C1a
Ru2a–S1a–C4a
99.93(3)
116.2(1)
114.0(1)
Ru1a–S1a–C1a
Ru1a–S1a–C4a
Ru3a–C11a–O7a
118.7(1)
93.1(2)
159.0(3)
Ru3a–C14a–O10a 149.4(3)
Ru4a–C14a–O10a 130.3(2)
Complex 1a (isomer 2)
Ru1b–Ru3b
Ru2b–Ru3b
Ru3b–Ru4b
Ru2b–S1b
Ru1b–C15b
Ru4b–C14b
286.50(3) Ru1b–Ru4b 283.16(3)
280.42(3) Ru2b–Ru4b
284.97(3)
237.89(8)
193.2(3)
233.4(3)
278.54(3) Ru1b–S1b
236.77(7) Ru4b–C15b
266.2(3)
201.4(3)
Ru3b–C14b
Ru3b–Ru1b–Ru4b 58.540(8) Ru1b–Ru3b–Ru4b 60.131(8)
Ru1b–Ru4b–Ru3b 61.329(8) Ru3b–Ru2b–Ru4b 59.023(8)
Ru2b–Ru3b–Ru4b 61.304(8) Ru2b–Ru4b–Ru3b 59.673(8)
Ru1b–Ru3b–Ru2b 80.385(9) Ru1b–Ru4b–Ru2b 80.185(9)
Ru1b–S1b–Ru2b
Ru2b–S1b–C1b
Ru2b–S1b–C4b
100.86(3) Ru1b–S1b–C1b
115.0(1)
114.0(1)
117.3(1)
119.5(1)
Ru1b–S1b–C4b
Ru4b–C15b–O11b 162.4(3)
Ru4b–C14b–O10b 150.8(3)
Figure 3. Molecular structure of 3.
Ru3b–C14b–O10b 129.9(2)
Complex 1b
Table 2. Bond lengths [pm] and angles [°] of 3 and 4.
Complex 3
Ru1–Ru3
Ru2–Ru3
Ru3–Ru4
Ru2–S1
Ru2–C13
Ru4–C17
Ru3–Ru1–Ru4
Ru1–Ru4–Ru3
Ru2–Ru3–Ru4
Ru1–Ru3–Ru2
Ru1–S1–Ru2
Ru2–S1–C1
Ru2–S1–C4
Ru3–C17–O14
284.41(6) Ru1–Ru4
285.47(6) Ru2–Ru4
280.31(6) Ru1–S1
281.66(6)
285.01(6)
234.7(1)
191.7(6)
204.1(5)
Ru1–Ru2
Ru2–Ru3
Ru1–S2
Ru2–C10
275.05(8)
283.67(8)
244.5(2)
211.0(7)
226.2(7)
61.79(2)
60.58(2)
99.1(2)
Ru1–Ru3
Ru1–S1
Ru1–C10
Ru1–C11
286.99(7)
243.9(2)
205.0(7)
197.5(7)
237.2(1)
281.7(8)
226.9(5)
59.36(2)
60.81(2)
60.49(2)
79.41(2)
101.0(5)
117.0(2)
117.3(2)
148.4(4)
Ru3–C13
Ru3–C17
Ru1–Ru3–Ru4
Ru3–Ru2–Ru4
Ru2–Ru4–Ru3
Ru1–Ru4–Ru2
Ru1–S1–C1
Ru1–S1–C4
Ru3–C13–O10
Ru4–C17–O14
59.83(2)
58.86(2)
60.65(2)
79.95(2)
113.9(2)
114.1(2)
167.2(5)
130.7(4)
Ru2–C11
Ru1–Ru2–Ru3
Ru3–Ru1–Ru2
Ru1–S1–C1
Ru1–S2–C2
Ru2–Ru3–Ru1
S1–Ru1–S2
Ru1–S1–C6
Ru1–S2–C3
57.63(2)
83.94(6)
109.5(2)
107.5(2)
103.7(2)
Complex 4
Ru1–Ru1A
Ru1–S1
Ru1–C9
Ru1–Ru2–Ru1A
Ru1–S1–C1
Ru1–S2–C2
268.30(8)
246.2(1)
202.4(6)
54.87(2)
102.7(2)
104.1(2)
Ru1–Ru2
Ru1–S2
Ru1A–C9
Ru2–Ru1–Ru1A
Ru1–S1–C6
Ru1–S2–C3
291.14(6)
243.4(1)
204.7(5)
62.56(1)
107.8(2)
110.6(2)
The molecular structure of 3 is depicted in Figure 3; se-
lected bond lengths and angles are summarized in Table 2.
Compound 3 consists of a trigonal Ru3 core in which two
ruthenium centers (Ru2, Ru3) are coordinated by three or
four terminal CO ligands, respectively. The third Ru atom
The molecular structure of 4 is presented in Figure 4;
is coordinated by one CO ligand and C2S2 in a chelating selected bond lengths and angles are also depicted in
fashion. In addition, two bridging CO ligands complete the Table 2. Compound 4 crystallizes in the orthorhombic
coordination sphere of Ru1 and Ru2. The three metal– space group Pbcn, with Ru2 being situated on a crystallo-
metal bonds are significantly different, with the bond be- graphic glide plane (c). This leads to the fact that the atoms
tween Ru1 and Ru3 being the longest interaction in the mo- of only one half of the molecule are observed in symmetry-
lecule [286.99(7) pm vs. 275.05(8) pm for Ru1–Ru2 and independent positions, whereas the second half of the mole-
283.67(8) pm for Ru2–Ru3]. On the other hand, Ru1–Ru2, cule is created by applying the corresponding symmetry op-
which is the bond being bridged by two CO ligands, is the eration. This also leads to the crystallographically observed
shortest metal–metal bond in 3. One of the bridging CO syn arrangement of the C2S2 ligands. NMR spectra show
ligands adopts an almost perfectly symmetrical coordina- only one set of signals for C2S2 as well as for CO ligands.
tion mode with only small differences in terms of the Ru– This suggests that an average spectrum of highly fluxional
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Photochemical Synthesis of Ruthenium–Carbonyl Compounds
syn and anti isomers is observed. Both chelating ligands are
coordinated at the ruthenium centers, which are bridged by
two carbonyl ligands. Again the respective Ru1–Ru1A bond
is significantly shorter than the other metal–metal bonds.
Due to crystallographic symmetry in 4, both bridging CO
ligands show an identical coordination mode with only
slight differences in the Ru–C bond lengths.
Scheme 3. Oxidative cleavage of the Ru3 cluster core by the reaction
of 4 with chlorinated solvents.
ate 5, although much faster than the situation without at-
mospheric oxygen being present. Dimerization then occurs
after the loss of one CO ligand from 5 to produce 6.
The molecular structure of 6 is presented in Figure 5;
selected bond lengths and angles are summarized in
Table 3. The center of the Ru2Cl2 ring represents a crystal-
lographic center of inversion that leads to an anti orienta-
tion of the two C2S2 ligands. 13C NMR spectra also showed
only one set of resonances with regards to the C2S2 moie-
ties. In the molecular structure of 6, both RuII centers are
octahedrally coordinated by the chelating bis(thioether)
C2S2, one CO ligand, and one terminal and two bridging
Figure 4. Molecular structure of 4.
To the best of our knowledge the only highly related
compounds that were structurally characterized were de-
rived from [Ru3(CO)12] by substituting three terminal CO
ligands at one ruthenium atom with tridentate thioether li-
gands (1,4,7-trithianonane and 1,5,9-trithiadodecane).[9]
In a previous report on the photochemical reaction of
[Ru3(CO)12] with thioether ligands in CHCl3, we observed
the formation of mono- and dinuclear RuII complexes that
contained chlorido ligands. The latter obviously originated
from the chlorinated solvent.[6] We therefore concluded that
in a first step thioether ligands substituted CO ligands that
were labilized by irradiation, and in a subsequent reaction
step the oxidative cleavage of the trinuclear ruthenium clus-
ter core took place. We therefore dissolved compound 4,
which corresponds to the proposed intermediates in chlori-
nated solvents, and analyzed the reaction products
(Scheme 3).
Under inert conditions, the trinuclear ruthenium com-
pound 4 upon being dissolved in chloroform or dichloro-
methane yielded the mononuclear ruthenium(II) complex
5. The reaction in CH2Cl2 proceeded considerably slower.
Compound 5 has been isolated from the photochemically
induced reaction of [Ru3(CO)12] with C2S2 in CHCl3 before,
and its spectroscopic and structural features have been de-
scribed in a previous report.[6] Nevertheless, if 4 is dissolved
in chloroform in the presence of oxygen, the dinuclear
chlorido-bridged complex 6 is produced in good yields. The
same compound may be obtained from 5 if a solution is
allowed to stand under air for another 2 d. Most probably
the reaction that starts from 4 also proceeds via intermedi- Figure 5. Molecular structure of 6.
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B. K. Maiti, H. Görls, O. Klobes, W. Imhof
FULL PAPER
erature procedure, and its identity was shown by comparison of
NMR spectra.[11] Solvents were dried and distilled before use.[12]
Photochemical reactions were performed in a water-cooled 150 mL
photoreactor with UV light irradiation of 150 W. IR spectra were
performed in a range of 400–4000cm–1 by using KBr pellets with
a Perkin–Elmer System 2000 device. Mass spectra were obtained
with a Finnigan MAT SSQ 710 device. NMR spectra were recorded
with a Bruker DRX 400 spectrometer (1H: 400.13 MHz; 13C:
100.62 MHz; solvent as internal standard). Elemental analyses
were performed at the Institute of Organic Chemistry and Macro-
molecular Chemistry, Friedrich Schiller University Jena.
chlorido ligands. As expected, Ru–Cl bonds in the central
four-membered ring are longer than the bond towards the
terminal chlorido ligands. Also, ruthenium–sulfur bonds
differ significantly due to the different trans effects of car-
bon monoxide and the bridging chlorido ligand.
Table 3. Bond lengths [pm] and angles [°] of 6.
Ru1–Cl1
Ru1–Cl2A
Ru1–S2
239.3(2)
244.8(2)
245.4(2)
174.97(6)
86.31(6)
89.4(2)
97.09(6)
94.2(2)
88.06(6)
88.07(6)
176.7(2)
Ru1–Cl2
Ru1–S1
Ru1–C9
Cl1–Ru1–Cl2A
Cl1–Ru1–S2
Cl2–Ru1–Cl2A
Cl2–Ru1–S2
Cl2A–Ru1–S1
Cl2A–Ru1–C9
S1–Ru1–C9
241.5(2)
231.0(2)
185.6(8)
92.84(6)
93.28(6)
83.52(6)
83.16(6)
175.98(7)
93.7(2)
Cl1–Ru1–Cl2
Cl1–Ru1–S1
Cl1–Ru1–C9
Cl2–Ru1–S1
Cl2–Ru1–C9
Cl2A–Ru1–S2
S1–Ru1–S2
S2–Ru1–C9
X-ray Structure Determinations: Intensity data were collected with
a Nonius Kappa CCD diffractometer by using graphite-monochro-
mated Mo-Kα radiation. Data were corrected for Lorentz polariza-
tion but not for absorption effects.[13,14] Crystallographic data as
well as structure-solution and refinement details are summarized
in Table 4. Structures were solved by direct methods (SHELXS)
90.3(2)
2
and refined by full-matrix least-squares techniques against Fo
(SHELXL-97).[15,16] Hydrogen atoms were included at calculated
positions with fixed thermal parameters. All non-hydrogen, non-
disordered atoms were refined anisotropically.[16] XP (SIEMENS
Analytical X-ray Instruments, Inc.) was used for structure represen-
tations. CCDC-776990 (1a), -776991 (1b), -776992 (3), -776993 (4),
and -776994 (6) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
To the best of our knowledge, 6 is the first structurally
characterized halido-bridged RuII complex with thioether
ligands. All related compounds for which structural data
are available exhibit either mono- or bidentate phosphane
ligands or, in one case, diphosphaferrocene as a chelating
ligand.[10]
Synthesis and Analytical Data of 1a and 1b: [Ru3(CO)12] (105 mg,
0.16 mmol) and the corresponding thioether ligand (THT: 176 mg,
2 mmol; OXT: 208 mg, 2 mmol) were dissolved in anhydrous tetra-
hydrofuran (THF; 120 mL), and the resulting solution was stirred
and irradiated with UV light. Within 10 min, an orange precipitate
started to form. The reaction mixture was irradiated for 40 min.
The precipitate was collected by filtration and washed twice with
THF, thereby resulting in an orange solid (35 mg). The remaining
solution was concentrated to dryness, and the product mixture was
subjected to column chromatography on silica. By using light pe-
troleum (b.p. 40–60 °C) as the eluent, a yellow band was obtained
that was identified as [Ru3(CO)12] (THT: 40 mg, OXT: 46 mg). A
second red band was collected by using light petroleum/THF (10:1)
as eluent. Yield 1a: 6 mg (9% based on reacted [Ru3(CO)12]); 1b:
4 mg (6%). Crude 1a or 1b may be recrystallized from a concen-
trated solution in THF/light petroleum at 0 °C to produce single
crystals suitable for X-ray diffraction.
Conclusion
The photochemically induced reaction of [Ru3(CO)12]
with monodentate and bidentate thioether ligands in THF
leads to the formation of ruthenium–carbonyl cluster com-
pounds with the respective thioether ligands. In the case of
monodentate thioethers, tetranuclear compound 1 is ob-
served in low yields next to polymeric material. If bidentate
ligands are used, trinuclear substitution products 3 and 4
with one and two bis(thioether) ligands are observed. The
latter may be oxidatively cleaved upon reaction with chlori-
nated solvents under inert conditions or under atmospheric
oxygen. This reaction allows the isolation of the first struc-
turally characterized halido-bridged dinuclear RuII complex
with thioether ligands 6. This compound may serve as the
starting compound to mononuclear ruthenium compounds
of the general formula [Ru(CO)Cl2(RSʝSR)L] after cleav-
ing chlorido bridges with additional Lewis basic ligands L.
In addition, the reaction of 4 to mononuclear compounds
5 sheds some light on highly related photochemical reac-
tions in CHCl3 as solvent in which compounds of this type
are the main products. With respect to the results described
herein, it is highly reasonable that the reaction in CHCl3
initially also produces substitution products of type 4,
which are then converted in situ into complexes of type 5.
Compound 1a: 1H NMR ([D8]THF, 298 K): δ = 2.44 (br., 4 H,
CH ), 3.71 (br., 4 H, SCH ) ppm. IR (KBr): ν = 1613, 1873, 1983,
˜
2
2
2024, 2081 (CO), 2963 (C–H of THT) cm–1. MS (FAB, nitrobenzyl
alcohol): m/z = 857 [M + H]+, 829 [M + H – CO]+, 801 [M + H –
2 CO]+, 773 [M + H – 3 CO]+, 745 [M + H – 4 CO]+, 717
[M + H – 5 CO]+, 688 [M – 6 CO]+, 660 [M – 7 CO]+, 632 [M – 8
CO]+, 604 [M – 9 CO]+. C17H8O13Ru4S1 (856.58): calcd. C 23.83,
H 0.93, S 3.74; found C 25.08, H 1.27, S 2.92.
Analytical Data of the Precipitate: Found C 18.50, H 0.69, S 0.55.
IR (KBr): ν = 511, 591, 822. 1102, 1263, 1512, 1603, 2037, 2960,
˜
3436 cm–1.
Compound 1b: 1H NMR ([D8]THF, 298 K): δ = 2.65–2.82 (m, 4 H,
Experimental Section
SCH ), 4.18–4.34 (m, 4 H, OCH ) ppm. IR (KBr): ν = 1619, 1884,
˜
2
2
General: All procedures were carried out under argon in anhydrous,
freshly distilled solvents. [Ru3(CO)12] was purchased from ABCR;
1,4-oxathiane and tetrahydrothiophene were purchased from Ald-
rich and used without further purification. 1-[2-(Propylsulfanyl)-
ethylsulfanyl]propane was synthesized according to a modified lit-
1986, 2033, 2083 (CO), 2963 (C–H of OXT) cm–1. MS (FAB, ni-
trobenzyl alcohol): m/z = 872 [M]+, 844 [M – CO]+, 816 [M – 2
CO]+, 788 [M – 3 CO]+, 760 [M – 4 CO]+, 732 [M – 5 CO]+, 704
[M – 6 CO]+, 676 [M – 7 CO]+, 648 [M – 8 CO]+, 620 [M – 9
CO]+, 463 [Ru(CO)2(OXT)]+, 398 [Ru2(CO)7]+, 341 [Ru2(CO)5]+.
1550
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 1545–1552

Photochemical Synthesis of Ruthenium–Carbonyl Compounds
Table 4. Crystal data and refinement details for the X-ray structure determinations of 1a, 1b, 3, 4, and 6.
1a
1b
3
4
6
Empirical formula
Mr [gmol–1]
T [°C]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
C17H8O13Ru4S
856.57
–90(2)
monoclinic
C2/c
28.6136(6)
16.9148(3)
19.3762(2)
90
C17H8O14Ru4S
872.57
–140(2)
monoclinic
P21/c
9.3671(5)
14.8469(7)
17.1782(7)
90
C18H18O10Ru3S2
761.65
–90(2)
monoclinic
Cc
19.5255(11)
11.4502(8)
14.5467(6)
90
C24H36O8Ru3S4
883.98
–90(2)
orthorhombic
Pbcn
14.2198(8)
15.8002(8)
14.3596(7)
90
C18H36Cl4O2Ru2S4·2CHCl3
995.38
–140(2)
monoclinic
P21/c
12.5166(6)
7.4571(3)
20.6840(9)
90
β [°]
92.505(1)
90
9369.0(3)
16
2.429
26.84
96.574(3)
90
2373.31(19)
4
2.442
26.54
127.680(3)
90
2573.9(3)
4
1.965
19.47
90
90
3226.3(3)
4
1.820
102.750(3)
90
1882.99(15)
2
1.756
17.53
γ [°]
V [Å3]
Z
ρ [gcm–3]
μ [cm–1]
16.87
Measured data
Data with IϾ2σ(I)
Unique data/Rint
wR2 (all data, on F2)[a]
R1 [IϾ2σ(I)][a]
s[b]
32772
9047
10711/0.0328
0.0564
0.0253
1.021
0.599/–0.948
–
16495
3613
5429/0.0814
0.0770
0.0403
0.952
0.875/–0.877
–
8692
4150
5000/0.0465
0.0730
0.0367
0.970
0.575/–0.870
–0.10(4)
20469
2075
12211
2774
3688/0.1371
0.0888
0.0427
0.925
0.621/–0.756
–
4307/0.0769
0.1743
0.0623
1.012
2.569/–1.280
–
Residual density [eÅ–3]
Flack parameter
2
2 2
2
[a] Definition of the R indices: R1 = (Σ||Fo| – |Fc||)/Σ|Fo|; wR2 = {Σ[w(Fo – Fc ) ]/Σ[w(Fo2)2]}1/2 with w–1 = σ2(Fo2) + (aP)2 + bP; P = [2Fc
+ max(Fo2)]/3. [b] s = {Σ[w(Fo – Fc ) ]/(No – Np)}1/2
.
2
2 2
C17H8O14Ru4S1 (872.58): calcd. C 23.39, H 0.91, S 3.65; found C (br., 4 H, CH2) ppm. 13C NMR ([D8]THF, 298 K): δ = 13.2 (CH3),
23.98, H 1.15, S 3.01.
23.2 (CH2), 35.9 (SCH2), 44.3 (SCH2), 207.8 (CO) ppm. IR (KBr):
ν = 1741, 1979, 2029, 2076 (CO), 2876, 2934, 2967 (C–H of C S )
˜
2
2
Analytical Data of the Precipitate: Found C 19.77, H 0.71, S 0.59.
cm–1. MS (FAB, nitrobenzyl alcohol): m/z = 761 [M]+, 733 [M –
CO]+, 718 [M–CO–Me]+, 705 [M – 2 CO]+, 690 [M – 2 CO –
Me]+, 677 [M – 3 CO]+, 662 [M – 3 CO – Me]+, 649 [M – 4 CO]+,
634 [M – 4 CO – Me]+, 621 [M – 5 CO]+, 606 [M – 5 CO – Me]+,
593 [M – 6 CO]+, 578 [M – 6 CO – Me]+, 565 [M – 7 CO]+, 550
[M – 7 CO – Me]+, 537 [M – 8 CO]+, 522 [M – 8 CO – Me]+, 509
[M – 9 CO]+, 494 [M – 9 CO – Me]+, 481 [M – 10 CO]+, 466 [M –
10 CO – Me]+, 451 [M – 10 CO – 2 Me]+, 437 [M – 10 CO – 2
Me – CH2]+, 423 [M – 10 CO – 2 Me – 2 CH2]+, 409 [M – 10 CO –
2 Me – 3 CH2]+. C18H18O10Ru3S2 (761.67): calcd. C 28.38, H 2.37,
S 8.41; found C 28.92, H 2.48, S 8.57.
IR (KBr): ν = 513, 591, 821. 1109, 1263, 1513, 1612, 1976, 2040,
˜
2960, 2963, 3429 cm–1.
When the insoluble precipitate (15 mg) that is formed during the
photochemical reaction of [Ru3(CO)12] and THT or OXT was sus-
pended in THF (5 mL) and stirred at room temperature in the pres-
ence of PPh3 (100 mg) for 6 d, the precipitate fully dissolved,
thereby resulting in an orange solution. After evaporation of the
solvent and washing of the orange residue with light petroleum
(b.p. 40–60 °C) (3ϫ), 2 was obtained as an yellow-orange solid.
Crystallization was achieved by diffusion of light petroleum into a
concentrated solution of 2 in THF at room temperature. Yield 2:
20 mg. MS and X-ray data correspond to results already pub-
lished.[8]
3
Compound 4: 1H NMR ([D8]THF, 298 K): δ = 1.12 (t, JH,H
=
7.2 Hz, 6 H, CH3), 1.81–1.95 (m, 4 H, CH2), 2.79–2.93 (m, 4 H,
CH2), 3.05–3.19 (m, 4 H, CH2) ppm. 13C NMR ([D8]THF, 298 K):
δ = 13.5 (CH3), 23.5 (CH2), 36.1 (SCH2), 44.5 (SCH2), 207.7 (CO)
Synthesis and Analytical Data of 3 and 4: [Ru3(CO)12] (105 mg,
0.16 mmol) was dissolved in THF together with C2S2 (2 mmol,
355 mg), and the solution was stirred and irradiated with UV light.
After 40 min, the solution was still clear, and, after evaporation of
the solvent, an orange-red oily residue formed. Chromatographic
workup of the crude reaction mixture first yielded [Ru3(CO)12]
(30 mg) by using light petroleum (b.p. 40–60 °C). With a mixture
of light petroleum/THF (10:1), 4 was eluted as a pink solution.
Encrease of the polarity of the eluent to light petroleum/THF (5:1)
led to the isolation of 3 as a red band. Yields: 3 {30 mg, 33% calcd.
on reacted [Ru3(CO)12]}, 4 (15 mg, 15%). In another experiment,
[Ru3(CO)12] (0.63 mmol, 400 mg) was irradiated together with C2S2
(7.58 mmol, 1.352 g) for 120 min. After chromatographic workup,
4 {149 mg, 30% based on reacted [Ru3(CO)12]} and 3 (79 mg, 18%)
were observed. Crystallization for 3 and 4 was possible by diffusion
of light petroleum into a concentrated solution of the respective
compound in THF at room temperature.
ppm. IR (KBr): ν = 1763, 1948, 2029 (CO), 2875, 2933, 2966 (C–
˜
H of C2S2) cm–1. MS (FAB, nitrobenzyl alcohol): m/z = 883 [M]+,
855 [M – CO]+, 827 [M – 2 CO]+, 799 [M – 3 CO]+, 784
[M – 3 CO – Me]+, 771 [M – 4 CO]+, 756 [M – 4 CO – Me]+, 743
[M – 5 CO]+, 728 [M – 5 CO – Me]+, 715 [M – 6 CO]+, 700 [M –
6 CO – Me]+, 687 [M – 7 CO]+, 672 [M – 7 CO – Me]+, 659 [M –
8 CO]+, 644 [M – 8 CO – Me]+, 629 [M – 8 CO – 2 Me]+, 615 [M –
8 CO – 2 Me – CH2]+, 601 [M – 8 CO – 2 Me – 2 CH2]+, 587 [M –
8 CO – 2 Me – 3 CH2]+, 573 [M – 8 CO – 2 Me – 4 CH2]+, 473
[Ru3S4C2H5]+. C24H36O8Ru3S4 (883.99): calcd. C 32.62, H 4.07, S
14.50; found C 32.83, H 4.38, S 13.88.
Synthesis and Analytical Data of 5 and 6: A sample of 4
(0.017 mmol, 15 mg) was dissolved in anhydrous CHCl3 (10 mL),
and the solution was kept under inert conditions at room tempera-
ture for 6 h. The color of the solution changed from pink to yellow.
After evaporation of the solvent, the residue was washed with light
petroleum (b.p. 40–60 °C) to give an orange solution that contained
Compound 3:. 1H NMR ([D8]THF, 298 K): δ = 1.09 (t, JH,H
=
3
7.2 Hz, 6 H, CH3), 1.83 (br., 4 H, CH2), 2.86 (br., 4 H, CH2), 3.07 [Ru3(CO)12] (3 mg, 27.6%). The remaining residue might be recrys-
Eur. J. Inorg. Chem. 2011, 1545–1552
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1551

B. K. Maiti, H. Görls, O. Klobes, W. Imhof
FULL PAPER
topino, E. Nordlander, in Metal Clusters in Chemistry, vol. 2
(Eds.: P. Braunstein, L. A. Oro, P. R. Raithby), Wiley-VCH,
Weinheim, 1999, pp. 741–781.
tallized by diffusion of light petroleum into a solution in CHCl3 to
yield 5 (9 mg, 43%). The identity of 5 was demonstrated by com-
parison of analytical data with the compound produced from pho-
tolysis of [Ru3(CO)12] in CHCl3 in the presence of C2S2.[6] When
the above-mentioned solution of 5 was exposed to air, orange
block-shaped crystals of 6 were produced after 2 d of standing at
room temperature. Yield 8 mg (62%).
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S 16.93; found C 28.92, H 4.86, S 16.55. IR (KBr): ν = 1967 (br.,
˜
CO), 2873, 2929, 2965 (C–H of C2S2) cm–1. 1H NMR (CD2Cl2,
3
4
298 K): δ = 1.01 (dt, JH,H = 7.2 Hz, JH,H = 2.4 Hz, 6 H, CH3),
3
4
1.22 (dt, JH,H = 7.2 Hz, JH,H = 2.4 Hz, 6 H, CH3), 1.50–1.69 (m,
4 H, CH2), 1.89–2.08 (m, 4 H, CH2), 2.11–3.35 (m, 16 H, CH2)
ppm. 13C NMR (in CD2Cl2, 298 K): δ = 13.2 (br., CH3), 14.1
(CH3), 22.7 (CH2), 29.4 (CH2), 31.9 (CH2) ppm. MS (FAB, ni-
trobenzyl alcohol): m/z = 757 [M]+, 729 [MH – CO]+, 614 [M – 2
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Published Online: February 23, 2011
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