Reactivity of electron-poor decamethyl-1,3-diboraruthenocene with sulfur and phosphorus compoundsDedicated to Professor Bernt Krebs on the occasion of his 65th birthday

Article abstract of DOI:10.1016/j.jorganchem.2003.09.053

Decamethyl-1,3-diboraruthenocene [(η⁵-C₅ Me₅)Ru{η⁵-(CMe)₃(BMe)₂}] (1) reacts with cyclo-octasulfur in hexane to give [(η⁵ -C₅Me₅){η⁵-(CMe)₃ (BMe)₂}Ru=S] (3), which may also be obtained from 1 and propylene sulfide. 1 reacts with H₂S to form the ruthenathiacarboranyl complex [(η⁵-C₅ Me₅)Ru{η⁴-(CMe)₃(BMe)₂S}] (6), for which a nido-structure is proposed. The isomeric compounds 3 and 6 have different stabilities: 3 loses sulfur and unexpectedly the closo-cluster [(η⁵-C₅Me₅) ₂Ru₂H(CMe)₃(BMe)₂] (4) is formed with hydrogen bridging the basal and apical Ru centers. Reaction of 1 with carbonylsulfide (COS) yields the dinuclear ruthenium compound [(η⁵-C₅Me₅)Ru{η⁵ -(CMe)₃(BMe)₂(S)(COBMe)}]₂ (7) in which two B-O groups bridge two ruthenium complexes. Its formation results from a complex reaction sequence: sulfur inserts into the diborolyl ring and the ligand CO forms an oxygen-boron bridge to a second molecule, followed by insertion of the carbonyl carbon into the double bond of the diboraheterocycle. Carbon disulfide reacts with 1 to give the dinuclear complex 8 with two CS₂ molecules connecting the ruthenium centers. When 1 and P₄ are heated in toluene, the sandwich 9 is obtained by formal i nsertion of a P-H group into the diborolyl ring of 1 and the triple-decker [{η⁵-(C₅Me₅)Ru }₂{μ-(MeC)₃P(MeB)₂} (10) is detected in the mass spectrum. The phosphaalkyne P≡CtBu inserts into 1 to give the ruthenaphosphacarborane [(η⁵ -C₅Me₅)Ru{(CMe)₂(BMe)(PC t Bu)(CMe) (BMe)}] (11) in high yield. Phosphanes react with 1 to give weak donor-acceptor complexes 1 · PH₂R (12) (R=Ph, H). The compositions of the compounds are deduced from spectroscopic and analytical data and are confirmed for 4 and 7 by X-ray structural analyses.

Full text of DOI:10.1016/j.jorganchem.2003.09.053

Journal of Organometallic Chemistry 689 (2004) 429–437
www.elsevier.com/locate/jorganchem
Reactivity of electron-poor decamethyl-1,3-diboraruthenocene
with sulfur and phosphorus compounds
*
Bettina Bach, Yong Nie, Hans Pritzkow, Walter Siebert
Anorganisch-Chemisches Institut der Universit€at Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany
Received 13 August 2003; accepted 15 September 2003
Dedicated to Professor Bernt Krebs on the occasion of his 65th birthday
Abstract
Decamethyl-1,3-diboraruthenocene [(g5-C5Me5)Ru{g5-(CMe)3(BMe)2}] (1) reacts with cyclo-octasulfur in hexane to give [(g5-
C5Me5){g5-(CMe)3(BMe)2}Ru@S] (3), which may also be obtained from 1 and propylene sulfide. 1 reacts with H2S to form the
ruthenathiacarboranyl complex [(g5-C5Me5)Ru{g4-(CMe)3(BMe)2S}] (6), for which a nido-structure is proposed. The isomeric
compounds 3 and 6 have different stabilities: 3 loses sulfur and unexpectedly the closo-cluster [(g5-C5Me5)2Ru2H(CMe)3(BMe)2] (4)
is formed with hydrogen bridging the basal and apical Ru centers. Reaction of 1 with carbonylsulfide (COS) yields the dinuclear
ruthenium compound [(g5-C5Me5)Ru{g5-(CMe)3(BMe)2(S)(COBMe)}]2 (7) in which two B–O groups bridge two ruthenium
complexes. Its formation results from a complex reaction sequence: sulfur inserts into the diborolyl ring and the ligand CO forms an
oxygen–boron bridge to a second molecule, followed by insertion of the carbonyl carbon into the double bond of the diborahet-
erocycle. Carbon disulfide reacts with 1 to give the dinuclear complex 8 with two CS2 molecules connecting the ruthenium centers.
When 1 and P4 are heated in toluene, the sandwich 9 is obtained by formal insertion of a P–H group into the diborolyl ring of 1 and
the triple-decker [{g5-(C5Me5)Ru}2{l-(MeC)3P(MeB)2} (10) is detected in the mass spectrum. The phosphaalkyne PBCtBu inserts
into 1 to give the ruthenaphosphacarborane [(g5-C5Me5)Ru{(CMe)2(BMe)(PCtBu)(CMe)(BMe)}] (11) in high yield. Phosphanes
react with 1 to give weak donor–acceptor complexes 1 ꢀ PH2R (12) (R ¼ Ph, H). The compositions of the compounds are deduced
from spectroscopic and analytical data and are confirmed for 4 and 7 by X-ray structural analyses.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Ruthenium; Sandwich complexes; Diboroles; Sulfur; Phosphorus
1. Introduction
between BH3 ꢀ thf and 1 leads to (1,2,3,5,6-pentamethyl-
4-hydro-2,3,5-tricarbahexaboranyl)(g5-pentamethylcy-
clopentadienyl)ruthenium [1] (2), which is formed by
oxidative addition of BH3 to 1, followed by HB–Hꢀ ꢀ ꢀBMe
interaction and migration of this BMe group to the apical
position and BH to the basal position of the pyramidal
ligand (Scheme 1). In this paper we describe reactions of
sulfur and phosphorus compounds with 1.
Organometallic complexes of the iron triad having
fewer than 18 valence electrons (VE) are of particular
interest for catalytic and preparative studies. Recently we
reported the synthesis and some reactions of the title
compound 1, obtained from 1,2,3,4,5-pentamethyl-2,3-
dihydro-1,3-diborole, methyl lithium, and [(C5Me5)-
RuCl]4 [1]. The electron-poor sandwich compound 1,
which is presumed to be folded along the Bꢀ ꢀ ꢀB vector like
the corresponding iron compound (ca. 41°), forms donor–
acceptor compounds with CO [2] and isonitrile [1], and a
classic dihydride complex with H2. A complex reaction
2. Results and discussion
2.1. Formation of the sulfur complexes 3, 6 and the
diruthenacarborane 4
* Corresponding author. Tel.: + 49-622-154-8485; fax: +49-622-154-
6235.
E-mail address: walter.siebert@urz.uni-heidelberg.de (W. Siebert).
Reaction of violet 1 with cyclo-octasulfur leads to the
yellow decamethyl-1,3-diboraruthenocene-sulfide 3,
0022-328X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.09.053

430
B. Bach et al. / Journal of Organometallic Chemistry 689 (2004) 429–437
decomposition of 4 takes place and presently it is not
known if the reverse reaction proceeds. The possible
rearrangements of 4/40 are related to that of the isomeric
triple-deckers 50, 5 and their isomeric closo-clusters
reported by Grimes et al. [4] (Scheme 3). In the red 50
and the green triple-decker complexes [(g5-C5Me5)Co]2
(l,g5-C2B3H5)] (5) the carbon atoms of the bridging
ligands are adjacent and separated, respectively. Heating
the red species 50 with the cluster atoms Co2C2 in
1,7,2,3-position to 200–250 °C leads to green 5 via the
isolable 1,2,4,5- and 1,2,3,5-intermediates. In the latter
compounds the (C5H5)Co moieties occupy both apical
and basal positions. It has been suggested that this re-
arrangement proceeds via cooperative movements of the
atoms on the surface of the seven-vertex polydeltahedral
clusters. Scheme 3 indicates, that the 1,7,2,3 ! 1,2,4,5
conversion is reversible.
As described in Scheme 1, the reaction between 1 and
BH3 ꢀ thf gives the tricarbahexaboranyl–ruthenium
complex 2 with elimination of dihydrogen. Analogously,
H2S reacts with 1 in pentane to give the tricarbathia-
hexaboranyl–ruthenium complex 6. Two 11B-NMR
signals of equal intensity indicate the presence of a
thiacarboranyl ligand with one boron (d ¼ ꢁ12:2 ppm)
in the apical position. From the broad signal at d ¼ 43
ppm a decreased coordination number of the other bo-
ron atom is deduced compared to that of 1. The for-
mation of 6 may occur according to Scheme 4: After
oxidative addition of H2S to the ruthenium center the
S–H bond interacts with one B–Me group, and results in
its migration into the apical position. Simultaneously,
the S–H group moves into the empty ring position to
yield, with elimination of hydrogen, the ruthenathia-
RRuu
H
.
H3B thf
H
Ru
Ru
B
-THF
- [H 2
]
B
B
H
H
B
B
B
B
BB
1
2
Scheme 1. Formation of the ruthenacarboranyl complex 2.
which is also obtained from 1 and propylene sulfide, even
at )50 °C, in higher yield (Scheme 2). Its mass spectro-
metric and NMR data support the proposed composi-
tion. In the 1H-NMR spectrum of 3, five signals for CMe
and BMe groups of the 1,3-diborolyl ring appear and in
the 11B-NMR spectrum two signals in a 1:1 ratio
(d ¼ 21:5; 15:1 ppm) indicate that the sulfur atom is un-
symmetrically bound with respect to the heterocycle.
Surprisingly, after some weeks crystals of the di-
ruthenacarborane 4 and cyclo-octasulfur separated from
a hexane solution of 3 at )20 °C. In addition, uniden-
tified products were also present in the solution. The
composition of the closo-cluster 4 was deduced from
spectroscopic data and an X-ray structure analysis (see
below). Attempts to synthesize 4 by various routes [3]
led instead to the isomeric closo-cluster/triple-decker 40,
which had been obtained initially by reacting
[(C5Me5)RuCl]4 with an excess of NaH in the presence
of the 1,2,3,4,5-pentamethyl-2,3-dihydro-1,3-diborole
heterocycle [2].
Ru
Ru
Ru
Ru
?
H
B
B
B
B
B
Ru
B
Ru
H
H
1
Co
Co
B
B
Co
B
B
Co
B
H
H
H
2
3
Co
H
Co
B
B
H
H
B
B
B
H
H
H
cluster
representation
triple-decker
representation
H
4
4’
B
H
B
H
Co
7
Co
As 4 might undergo rearrangement to form the triple-
decker 40 we monitored the thermal reaction by 1H- and
11B-NMR spectra. However, in toluene above 80 °C
5’ (1,7,2,3)
1,2,4,5
1,2,3,5
5 (1,7,2,4)
Scheme 3. Rearrangement of isomeric Co2C2B3 compounds.
1/8 S8
or
C3H6S
Ru
1 +
H
Ru
+ S8
S
+ H2S
H
S
H
Ru
B
- C3H6
B
Ru
Ru
Ru
B
- [H2]
S
B
B
B
B
B
B
B
3
4
1
6
Scheme 2. Formation of the diboraruthenocene-sulfide 3 and further
reaction to the diruthenacarborane 4.
Scheme 4. Formation of the ruthenathiacarborane 6.

B. Bach et al. / Journal of Organometallic Chemistry 689 (2004) 429–437
431
carborane 6. According to the cluster electron counting
rules, the seven vertex cluster 6 with 18 skeletal electrons
(SE) is expected to form a nido-structure with one non-
triangular face (RuC2B).
Alternatively, 6 may be described as an 18 VE com-
plex, in which the g4-ligand 4-thia-2,3,5-tricarbahexa-
boranyl supplies 5e for bonding to the metal. As the
anionic thiacarbaboranyl ligand has an arachno-struc-
ture (2n + 6 ¼ 18 SE), it donates as a neutral species 5e
(each carbon 1e and 2e from the sulfur). The apical
boron of an arachno ligand [5] does not contribute any
electrons to the bonding between ruthenium and thia-
carboranyl ligand (see Scheme 4).
C2B2CS rings. This is accompanied by the formation of
an exocyclic boryl group from an endo-cyclic boron
atom and the new C3BSC cycle is now g5-bonded to the
ruthenium center. As a result, the two B–O bridges build
a 10-membered ring by connecting two 18 VE com-
plexes.
The 1H-NMR spectrum shows the expected five
singlets for the methyl groups of the heterocycle and one
for the C5Me5 protons. In the 11B-NMR spectrum, the
signal of the oxygen-bonded boron atom is observed at
d ¼ 60:9 ppm, whereas the signal for the boron inter-
acting with ruthenium is observed at d ¼ 20:4 ppm
(similar to that of 1). The high-resolution FAB mass
spectrum of 7 provides further evidence for its compo-
sition; its molecular structure is shown in Fig. 2.
A similar reaction of 1 with carbon disulfide [8,9] in
hexane at low temperature leads to the coordination of
CS2 to 1, followed by dimerisation to give 8. According
to NMR and mass spectrometric data, two CS2 mole-
cules bridge two ruthenium centers giving a dimeric
complex. One of the two 11B-NMR signals indicates an
interaction of the C@S sulfur atom with one of the
boron atoms (at d ¼ 11:4 ppm). This should cause a
tilting of the 1,3-diborolyl and a change from g5 to g4-
bonding of the 1,3-diborolyl ring to the metal. The sig-
nal of the other boron is at d ¼ 31:1. Contrary to the
reaction with COS, neither cleavage of the CS bond in
CS2 nor insertion into the diborolyl ring is observed (see
Scheme 6).
2.2. Reactions of 1 with COS and CS2 to give the
dinuclear complexes 7 and 8
A complex reaction of carbonylsulfide [6,7] with 1 in
hexane produces a brown solution from which the yel-
low dinuclear complex 7 can be isolated in 63% yield.
The X-ray structure analysis (see Scheme 5) reveals that
7 is composed of two doubly bridged 18 VE complexes.
Its formation may occur according to the following se-
quence of reactions:
In the first step, COS is coordinated via its CS p-bond
to the ruthenium atom of electron-poor 1 to give an
intermediate 18 VE complex. This is followed by
cleavage of the CS bond and insertion of sulfur into the
B1–C2 bond of the 1,3-diborolyl ligand. The resulting
g3-C2B2CS six-membered heterocycle forms with the
CO ligand of a second sandwich intermediate an inter-
molecular acceptor–donor interaction to give a dimeric
complex which is stabilized by insertion of two carbene
centers of the CO ligands into the double bond of the
2.3. Reactions of phosphorus, phosphaacetylene and
phosphanes with 1
As described above, sulfur and sulfur compounds
exhibit a unique reactivity towards 1. In the following
we report on the reaction of 1 with phosphorus. Heating
a toluene solution of 1 and P4 results in formation of a
yellow–orange reaction mixture from which the sand-
wich 9 was isolated. However, mass spectroscopic data
of the crude product also indicates the presence of the
triple-decker 10, which could not be separated. It is
likely that insertion of phosphorus into 1 leads to the
paramagnetic 17 VE sandwich (9–H)Å which picks up a
hydrogen atom from toluene to give the diamagnetic
sandwich 9 with an incorporated P-H group as proven
C
OI
Ru
B
B
2 COS
Ru
S
B
Ru
2
2
C
O
S
S
B
B
B
IO
Ru
C
B
B
1
Ru
O
Ru
O
B
C
B
• •
B
B
B
B
S
S
S
S
B
S
B
Ru
S
B
• •
S
O
2 CS2
B
C
Ru
B
Ru
Ru
B
Ru
2
2
C
S
O
Ru
S
S
B
B
B
B
7
1
8
Scheme 5. Mechanism of the formation of 7.
Scheme 6. Reaction of 1 with CS2.

432
B. Bach et al. / Journal of Organometallic Chemistry 689 (2004) 429–437
1
+ P4
toluene
∆
+ PR12R2
Ru
PR12R2
Ru
B
12
R1
R2
a
H
H
b
c
B
H
Me
B
Ph Me
B
1
Ru
•
[Cp*Ru]
[H ]
Scheme 9. Formation of the phosphane adducts 12.
B
Ru
Ru
B
P
B
B
B
P
Ru
B
P
3,4,6,7-tetracarba-5-phosphaheptaboranyl ligand sup-
plies 5e for bonding to the metal [5] (see Scheme 8).
As indicated in Section 1 the ruthenium sandwich 1
shows excellent to good coordination properties towards
CO and isonitrile. Coordination of the small phos-
phanes PH3, PH2Ph and PMe3 results in the formation
of yellow, classic 18 VE complexes 12a, b and c, whereas
no interaction between 1 and PPh3 is observed (see
Scheme 9).
H
9 (18VE)
(9-H)• (17VE)
Scheme 7. Reaction of 1 with P4.
10
by 31P- and 1H-NMR spectroscopy. The diamagnetic
triple-decker sandwich 10 may be formed when the
Cp*Ru group of 1 stacks with the sandwich (9–H)Å (see
Scheme 7).
The reaction of PH3 and PH2Ph with 1 give the
adducts 12a, b almost quantitatively. Their identifica-
tion follows from spectroscopic data. In the 11B-NMR
spectrum, the adducts 12a and 12b exhibit only one
broad signal at d ¼ 32 ppm for 12a and d ¼ 29 ppm for
When PBCtBu [10–13] is added to 1 in hexane, the
color of the solution immediately changes from violet to
orange and the tetracarbaphosphaheptaboranyl com-
plex 11 is formed. Its composition follows from mass
spectrometric and NMR data. The 11B-NMR spectrum
exhibits two signals in a 1:1 ratio (d ¼ ꢁ0:3; 32:1 ppm),
which indicate that one boron is in the apical position
(d ¼ ꢁ0:3 ppm) and the other has a weak interaction
with the metal. The exact structure cannot be deduced
from the spectroscopic data. We propose that phos-
phaacetylene is pre-coordinated side-on to the ruthe-
nium center which is followed by migration of one BMe
group into the apical position. In the next step, insertion
of the coordinated PꢂCtBu into the heterocycle occurs
via C–C and C–P coupling to give the ruthenaphos-
phacarborane 11 with a BCCCPC face of the phos-
phacarborane. It was pointed out by a referee that ‘‘in
principle an isomer of 11 is possible in which PꢂC has
inserted the other way round, to give a species with a
BCCPCC six atom face’’.
1
12b, whereas the H-NMR spectrum shows two signals
for BMe and three signals for CMe of the 1,3-diborolyl
ring. Furthermore, phosphorus–hydrogen couplings
were only observed for one of the BMe groups and the
methyl group on C2 of 12a and 12b and additionally
for one of the methyl groups connected to the C@C
double bond of 12b. This indicates that the phosphane
ligand is not symmetrically bonded with respect to the
boron heterocycle; a similar situation was observed for
the sulfur ligand in 3. One single doublet for the five
methyl groups of the cyclopentadienyl ring at d ¼ 1:45
ppm (5J PH ¼ 4.0 Hz) for 12a and d ¼ 1:38 ppm (5JPH
¼
2.8 Hz) for 12b indicates, that free rotation of the
carbacycle occurs. Due to coupling with the directly
bonded hydrogen atoms, the 31P-NMR spectrum of 12a
shows a quartet at d ¼ ꢁ81:5 ppm (1JPH ¼ 335.0 Hz)
and for 12b a triplet at d ¼ 11:1 ppm (1JPH ¼ 341.7 Hz),
respectively. Compared with non-coordinated phos-
phanes, the signals are clearly shifted to higher fre-
quencies (D ¼ 173 ppm for 12a and 133 ppm for 12b).
Above 85 °C decomposition of 12a occurs; the phos-
phane ligand dissociates and 1 is reformed. 12b is
thermally even less stable and begins to decompose at
60 °C.
According to the Wade–Mingos rules [14,15], 11 with
eight cluster atoms and 20 skeletal electrons is expected
to have a nido-structure. Alternatively, 11 may be
described as an 18 VE complex, in which the arachno-
Addition of PMe3 to 1 in toluene at 0 °C leads to the
labile complex 12c which could not be isolated. It de-
composes when warming to room temperature and the
weakly bonded trimethylphosphane may be easily re-
moved in vacuum. The solution of the complex 12c has
been studied by 11B- and 31P-NMR measurements. In
the 11B-NMR spectrum the complex exhibits one signal
at d ¼ 27 ppm and the 31P-NMR shows a singlet at
d ¼ ꢁ48:8 ppm which is shifted to low field (13 ppm)
compared with free PMe3.
tBu
+ P CtBu
C
Ru
Ru
B
Ru
P
tBu
P
B
B
B
B
B
1
11
Scheme 8. Formation of the ruthenaphosphacarbonane 11.

B. Bach et al. / Journal of Organometallic Chemistry 689 (2004) 429–437
433
2.4. X-ray structure analyses of 4 and 7
C5Me5(Ru1) and C3BRu2 form an angle of 13.6°. The
boron atom B7 is located in a five coordinate cluster
ꢀ
position having a distance of 1.124 A to the plane of the
C3BRu heterocycle (see Table 1).
2.4.1. Crystal structure of 4
In agreement with the cluster electron count, the di-
ruthenacarborane 4 adopts a closo structure. The mo-
lecular structure is shown in Fig. 1. Ru1 and B7 occupy
the apical positions of a pentagonal bipyramid. The
ruthenium atom Ru2 is part of the pentagon and the
2.4.2. Crystal structure of 7
The crystal structure analysis shows 7 to have an
inversion center (Fig. 2). A non-planar 10-membered
ring connects two ruthenium complexes to form a di-
ꢀ
Ru1–Ru2 edge (2.747 A) is bridged by H1 connecting
the two ruthenium centers via a 3c, 2e bond. Because of
the Ru1–H1–Ru2 interaction, the planes through
ꢀ
meric structure. Each ruthenium atom is 1.851 A above/
below the center of the g5-bonded C5Me5 ligand and the
best plane through the S1B1C1C2C3 ligand atoms has a
ꢀ
distance of 1.662
A
to the metal. The planes
S1B1C1C2C3/C3C4S1 form an angle of 52.4°. The dis-
tance between Ru1 and C4 is about 0.75 A longer than
ꢀ
C22
C17
C14
the distances to the coordinated carbon atoms of the
heterocycle (see Table 2).
C18
C16
C21
C13
C15
C19
C30
C20
Table 1
H1
ꢀ
Selected distances (A) and angles (°) in 4
Ru1
C29
Ru1–Ru2
Ru1–H1
Ru2–H1
Ru1–C (Cp*)
Ru2–C (Cp*)
Ru1–B5
Ru2–B7
Ru1–C6
Ru2–C6
Ru2–C3
C3–C4
2.7470(2)
1.74(3)
1.69(2)
B7–C3
B7–C4
B5–B7
1.770(4)
1.796(4)
1.827(3)
C25
Ru2
C11
C6
C3
C31
2.167–2.194(2)
2.173–2.243(2)
2.207(2)
B5
C24
C10
Ru1–H–Ru2
Ru2–C3–C4
C3–C4–B5
106.8(8)
C26
121.2(2)
113.4(2)
107.0(2)
122.3(1)
75.98(8)
72.23(7)
92.5(1)
C23
C4
2.150(2)
2.223(2)
C8
C4–B5–C6
C9
C27
B7
2.099(2)
2.079(2)
B5–C6–Ru2
C6–Ru2–C3
Ru1–Ru2–B7
Ru1–B5–B7
Ru1–C3–Ru2
Ru1–C6–Ru2
C28
1.475(3)
1.540(4)
C4–B5
B5–C6
B7–C6
C32
C12
1.523(3)
1.702(3)
79.11(6)
78.87(6)
Fig. 1. Molecular structure of 4.
C16
C11
C15
C17
O1A
C10
C12
C6
C14
C13
C2
C7
Ru1
C1
C19
C3
C18
B1
C2A
C4
C5
S1
C8
O1
B2
C9
Fig. 2. Molecular structure of 7.

434
B. Bach et al. / Journal of Organometallic Chemistry 689 (2004) 429–437
Table 2
2 h, the reaction mixture was filtered and the solvent
removed in vacuum. The brown residue was purified by
chromatography (silica gel, hexane) to give 3 as a yellow
solid. Yield: 140 mg (53%). (b) 42 mg (0.11 mmol) of 1
was dissolved in 10 ml of hexane and cooled to )50 °C.
207 mg (0.56 mmol) of methylthiirane was slowly added.
After warming to room temp. the solvent was removed
in vacuum and the brown residue was dissolved in 2 ml
of hexane and purified by chromatography on silica gel
using hexane as eluent to give 3. Yield: 30 mg (67%).
ꢀ
Selected distances (A) and angles (°) in 7
Ru1–C(Cp*)
Ru1–S1
Ru1–B1
Ru1–C1
Ru1–C2
Ru1–C3
S1–B1
2.191–2.234(2)
2.3852(5)
2.274(2)
2.238(2)
2.194(2)
2.205(2)
1.859(2)
1.516(3)
1.429(2)
1.433(2)
1.532(2)
1.870(2)
C4–B2
B2–O1
O1–C2A
1.602(3)
1.358(2)
1.396(2)
S1–B1–C1
B1–C1–C2
C1–C2–C3
C2–C3–C4
C3–C4–S1
B1–S1–C4
B2–C4–C3
O1–B2–C4
B2–O1–C2A
115.5(1)
122.0(2)
124.5(2)
118.2(1)
101.4(1)
104.87(8)
121.6(1)
127.6(2)
130.9(1)
B1–C1
C1–C2
C2–C3
C3–C4
C4–S1
1
M.p. 87 °C (dec.). H-NMR: d ¼ 0:85 (s, 3H, BCH3),
0.91 (s, 3H, BCH3), 1.39 (s, 15H, C5(CH3)5), 1.81 (s, 3H,
@CCH3), 1.83 (s, 3H, @CCH3), 1.91 (s, 3H, B2CCH3).
13C-NMR: d ¼ ꢁ3:51 (BCH3, br), 9.87 (C5(CH3)5),
10.67 (BCH3), 17.31 (@CCH3), 18.04 (@CCH3), 24.29
(B2CCH3), 88.34 (C5(CH3)5). 11B-NMR: d ¼ 21:5; 15:1.
MS (EI): m/z (%) ¼ 402 (Mþ, 100), 387 (Mþ–CH3, 41),
370 (Mþ–S, 87), 325 (Mþ–S–3CH3, 54), 233 (Cp*Ruþ–
4H, 63), 41 (C3Hþ5 , 96).
3. Conclusion
The electron-poor sandwich complex 1 reacts with
sulfur or sulfur-donating agents to yield the classic 18
VE complex 3 which slowly decomposes to give the di-
ruthenacarborane 4. With H2S, formation of the ruth-
enathiacarborane complex 6 occurs. Reactions of 1 with
the heterocumulenes COS and CS2 give the dinuclear
complexes 7 and 8, respectively. The crystal structure
analysis of 7 reveals two B–O bridges of a 10-membered
ring connecting the two ruthenium complexes. By for-
mal insertion of P–H into 1, sandwich 9 is formed and
the triple-decker 10 is observed in the mass spectrum.
Insertion of PꢂCtBu into 1 leads to the ruthenaphos-
phacarborane complex 11. With PR3 ligands, 1 forms
donor–acceptor compounds 12 of different stabilities:
PH3 > PH2Ph ꢃ PMe3.
4.2. 1,2-Bis(g5-pentamethylcyclopentadienyl)-(1,2-l-hydr-
ido-1,2-diruthenium-3,4,5,6,7-pentamethyl)-3,4,6-tri-
carbaheptaborane (4)
After several weeks at )20 °C, yellow 4 and cyclo -
octasulfur crystallized from a solution of 3 in hexane.
The residue of the hexane solution contained unidenti-
fied products. M.p. (4) 120 °C (dec.). 1H-NMR:
d ¼ ꢁ10:2 (s, 1H, Ru2H), )0.1 (s, 3H, BCH3), 0.68 (s,
3H, BCH3), 1.46 (s (br), 30H, C5(CH3)5), 1.65 (s, 3H,
CCH3), 1.68 (s, 3H, CCH3), 1.75 (s, 15H, C5(CH3)5),
1.88 (s, 3H, CCH3). 13C-NMR: d ¼ 10:8 (C5(CH3)5),
11.3 (C5(CH3)5), 14.4 (CCH3), 23.1 (CCH3), 32.0
(CCH3), 83.0 (C5(CH3)5), BCH3, CCH3 not observed.
11B-NMR: d ¼ 12 (br). MS (EI): m/z (%) ¼ 606 (Mþ,
13), 591 (Mþ–CH3, 19), 235 (Cp*Ruþ–H, 19), 57
(C4Hþ9 , 100).
4. Experimental
General: Experiments were carried out under argon,
which had been dried and purified before use. Solvents
were dried by conventional methods and saturated with
argon. NMR spectra were recorded on a Bruker DRX-
200 spectrometer (1H: 200.13 MHz, 13C: 50.32 MHz,
11B: 64.21 MHz) in C6D6 as solvent. Chemical shifts are
relative to TMS and BF3 ꢀ OEt2. The mass spectra were
recorded on Varian MAT CH7 and Jeol JMS 700
spectrometers (reference for HRMS is perfluorated ke-
rosine). GC mass spectra were recorded on a HP-5890 II
gas chromatograph with HP-5971 MSD (column HP-3,
12.5 m ꢄ 0.25 mm ꢄ 0.25 lm).
4.3. (g4-1,2,3,5,6-Pentamethyl-2,3,5-tricarba-4-thiahexa-
boranyl)(g5-pentamethyl-cyclopentadienyl)ruthenium (6)
Complex 1 (50 mg, 0.14 mmol) was dissolved in 20 ml
of pentane, and H2S was bubbled through the solution
for 5 min at a flow rate of 10 ml minꢁ1. The solvent was
removed in vacuum and the violet residue was dissolved
in 2 ml of hexane and purified by chromatography on
silica gel at room temp. using hexane as eluent. 6 was
isolated as a violet solid. Yield: 44 mg (78%). M.p.
130 °C. 1H-NMR: d ¼ ꢁ0:38 (s, 3H, BCH3), 0.63 (s, 3H,
BCH3), 1.49 (s, 3H, CCH3), 1.51 (s, 15H, C5(CH3)5),
1.88 (s, 3H, CCH3), 1.93 (s, 3H, CCH3). 13C-NMR:
d ¼ 0:8 (BCH3), 10.1 (C5(CH3)5), 13.3 (CCH3), 14.1
(CCH3), 19.8 (CCH3), 84.4 (C5(CH3)5), BCH3,
(BS)CCH3 and CCH3 not observed. 11B-NMR:
d ¼ ꢁ12:2; 43 (br), MS (CI): m/z (%) ¼ 402 (Mþ, 60),
387 (Mþ–CH3, 100), 375 (Mþ–CCH3, 97).
4.1. (g5-Pentamethyl-2,3-dihydro-1,3-diborolyl)(g5-pen-
tamethylcyclopentadienyl)-rutheniumsulfide (3)
(a) To a suspension of sulfur (50 mg, 1.56 mmol) in
pentane (50 ml), a solution of 1 (240 mg, 0.65 mmol)
dissolved in pentane (5 ml) was added. After stirring for

B. Bach et al. / Journal of Organometallic Chemistry 689 (2004) 429–437
435
4.4. Dinuclear ruthenium complex 7
4.7. (g5-Pentamethyl-2,3-dihydro-1,3-diborolyl)(g5-pen-
tamethylcyclopentadienyl)-ruthenium-phosphaacetylene
(11)
Complex 1 (147 mg, 0.40 mmol) was dissolved in 20
ml of hexane and gaseous COS bubbled through the
solution at room temperature. The colour changed
within a few minutes from violet to yellow. Dark yellow
7 crystallized from a solution in hexane. Yield: 108 mg
(63%). M.p. 80 °C (dec.). 1H-NMR: d ¼ 0:74 (s, 3H,
BCH3), 1.29 (s, 3H, BCH3), 1.43 (s, 15 H, C5(CH3)5),
1.57 (s, 3H, CCH3) 1.59 (s, 3H, CCH3), 1.75 (s, 3H,
CCH3), 13C-NMR: d ¼ 9:0 (CCH3), 9.7 (C5(CH3)5),
10.3 (CC H3), 17.6 (CCH3), 88.2 (C 5(CH3)5), 95.2 (CO).
11B-NMR: d ¼ 20 (br), 60 (br), MS (FAB): m/z (%) ¼
858 (Mþ, 5), 773 (Mþ–SBCMe2, 8), 537 (Mþ–Cp*Ru, –
SBCMe2, 45), 402 ([Cp*Ru(C3B2Me5)S]þ, 100), 233
([Cp*Ru–H]þ, 97).
Complex 1 (150 mg, 0.41 mmol) was dissolved in
hexane (10 ml) and a solution of PCC(CH3)3 (46 mg,
0.46 mmol) in hexane (5 ml) was slowly added. After
stirring for 30 min, the solvent was removed in vacuum
and 11 was obtained as a dark yellow solid. Yield: 153
1
mg (79%). H-NMR: d ¼ 0:31 (s, 3H, BCH3), 0.41 (s,
3H, BCH3), 1.27 (d, 3H, JPH ¼ 1.5 Hz, CCH3), 1.37 (d,
4
9H, JPH ¼ 1.8 Hz, C(CH3)3), 1.55 (s, 3H, CCH3), 1.66
(s, 15 H, C5(CH3)5), 1.70 (s, 3H, CCH3). 13C-NMR:
d ¼ 10:4 (CCH3), 10.5 (CCH3), 10.9 (C5(CH3)5), 23.0
3
(CC H3), 33.5 (d, C(C H3)3, JCP ¼ 12.1 Hz), 91.9
(C (CH3)5), BCH3, CCH3 and C(CH3)3 not observed.
5
11B-NMR: d ¼ ꢁ0:3; 32 (br). 31P-NMR (C6D6,80.9
MHz): d ¼ 51:1. MS(FAB): m/z (%) ¼ 470 [Mþ] (20).
HR MS for C23H39B2PRu: Calc. 470.2019; found:
470.1999; Dm ¼ 2:0 mmu.
4.5. Bis[(g5-pentamethyl-2,3-dihydro-1,3-diborolyl)-(g5-
pentamethylcyclopentadienyl)ruthenium-carbondisulfide]
(8)
4.8. (g5-Pentamethyl-2,3-dihydro-1,3-diborolyl)(g5-pen-
tamethylcyclopentadienyl)-ruthenium phosphane (12a)
40 mg (0.53 mmol) of CS2 was condensed into a so-
lution of 185 mg (0.50 mmol) 1 in toluene (20 ml) at
room temperature. The colour of the reaction mixture
immediately changed to brown. After stirring for 15 min
the solvent was removed in vacuum and dark yellow 8
was isolated from the brown residue by recrystallization
from hexane. Yield: 71 mg (32%). M.p. 75 °C (dec.). 1H-
NMR: d ¼ 0:59 (s, 3H, BCH3), 1.03 (s, 3H, BCH3), 1.40
(s, 15 H, C5(CH3)5), 1.47 (s, 3H, B2CCH3), 1.53 (s, 6H,
@CCH3), 13C-NMR: d ¼ 9:0 (C5(CH3)5), 10.0 (CCH3),
14.1 (CCH3), 88.1 (C5(CH3)5), 11B-NMR: d ¼
11:4; 33:1, MS (FAB): m/z (%) ¼ 891 (Mþ, 2), 537 (Mþ–
Cp*Ru(CS2BMe), 33), 421 (1/2 Mþ–BMe, 22), 388 (1/2
Mþ–SBMe, 40).
Complex 1 (0,54 g, 1.46 mmol) was dissolved in 100
ml of hexane, and PH3 gas bubbled through the solution
for 5 min at a flow rate of 10 ml minꢁ1. After removing
the solvent in vacuum, 12a was obtained as a yellow
solid. Yield: 588 mg (100%). M.p. 85 °C (diss. to starting
4
materials). 1H-NMR: d ¼ 0:65 (d, 3H, JPH ¼ 12 Hz,
4
BCH3), 0.93 (s, 3H, BCH3), 1.45 (d, 15H, JPH ¼ 4 Hz,
C5(CH3)5), 1.49 (s, 3H, @CCH3), 1.50 (s, 3H, @CCH3),
4
1.79 (d, 3H, JPH ¼ 2 Hz, B2CCH3), 4.96 (d, 3H,
1JPH ¼ 335 Hz, PH3). 13C-NMR: d ¼ 8:9 [C5(CH3)5],
10.7 (B2CCH3), 13.9 (@CCH3), 14.7 (@CCH3), 88.9 [C
5(CH3)5], BC H3, B2CCH3, @CCH3 not observed. 11B-
NMR: d ¼ 30 (br). 31P-NMR (C6D6,80.9 MHz):
1
4.6. (1,2,3,5,6-Pentamethyl-1,3-dibora-4-phospha-cyclo-
hexa-2,5-dienyl)(g5pentamethylcyclopentadienyl)ruthe-
nium (9)
d ¼ ꢁ81:5 (q, JPH ¼ 335 Hz, PH3).
4.9. (g5-Pentamethyl-2,3-dihydro-1,3-diborolyl)(g5-pen-
tamethylcyclopentadienyl)-ruthenium-phenylphosphane
(12b)
A toluene solution (10 ml) containing P4 (13 mg, 0.10
mmol) was added dropwise to a solution of 1 (150 mg,
0.41 mmol) in toluene (20 ml). The reaction mixture was
heated for 4 h under reflux. The colour slowly changed
from violet to brown. After removing the solvent in
vacuum 9 was isolated as an orange solid, contaminated
with the triple-decker 10. Yield: 87 mg (53%). M.p.
Phenylphosphane (81 mg, 0.74 mmol) was added
dropwise to a solution of 1 (275 mg, 0.74 mmol) in 20 ml
of toluene. After stirring for 30 min, the solvent was
removed in vacuum. 12b was obtained as a yellow solid.
Yield: 300 mg (85%). M.p. 60 °C (diss. to starting ma-
1
4
terials). 1H-NMR: d ¼ 0:56 (d, 3H, JPH ¼ 9.6 Hz,
160 °C. H-NMR: d ¼ 0:21 (s, 3H, BCH3), 0.91 (s, 3H,
BCH3), 0.96 (s, 3H, BCH3), 1.38 (d, 15H, 4JPH ¼ 2.8 Hz,
C5(CH3)5), 1.48 (d, 3H, 4JPH ¼ 3.1 Hz, @CCH3), 1.53 (s,
BCH3), 1.40 (s, 3H, B2CCH3), 1.43 (C5(CH3)5, 1.56 (s,
3H, @CCH3), 1.62 (s, 3H, @CCH3), 13C-NMR:
d ¼ 10:0 (C5(CH3)5), 83.5 (C5(CH3)5), BCH3, CCH3,
not observed. 11B-NMR: d ¼ 26 (br), 31P-NMR (C6D6,
4
3H, @CCH3), 1.75 (d, 3H, JPH ¼ 1.8 Hz, B2CCH3),
1
1
5.88 (dd, 2H, JPHa ¼ 335.1 Hz, JPHb ¼ 346.7 Hz,
2JHaHb ¼ 6.1 Hz, PH2), 7.10–7.13 (m, 2H, PPh), 7.38–
7.49 (m, 3H, PPh). 13C-NMR: d ¼ 10:3 (B2CCH3), 10.7
[C5(CH3)5], 13.5 (@CCH3), 14.5 (@CCH3), 89.4
1
80.9 MHz): d ¼ ꢁ85:3 (d, PH, JPH ¼ 263 Hz)), MS
(FAB): m/z (%) ¼ 636 (10þ, 8), 605 (10þ–P, 20), 401
(Mþ, 100).

436
B. Bach et al. / Journal of Organometallic Chemistry 689 (2004) 429–437
Table 3
Crystal and collection parameters for compound 4 and 7
Identification code
4
7
Empirical formula
Formula weight
Temperature
C28H46B2Ru2
606.41
C38H60B4O2S2Ru2 ꢀ C6H14
944.53
103(2) K
190(2) K
monoclinic
P21=n
Crystal system
Space group
monoclinic
P21=n
ꢀ
Unit cell (A, °)
a
b
c
9.0783(4)
15.6274(8)
19.901 (1)
90
8.7270(6)
11.2703(7)
23.247(2)
90
a
b
c
98.866 (1)
90
98.393(1)
90
3
ꢀ
V (A )
Z
2789.6(2)
4
1.444
2262.0(3)
2
1.387
Calculated density (g/cm3)
Absorption coefficient (mmꢁ1
)
1.096
1248
0.795
988
F ð000Þ
Crystal size (mm3)
Maximum (°)
Index ranges
0.33 ꢄ 0.22 ꢄ 0.17
32.04
0.30 ꢄ 0.30 ꢄ 0.20
32.04
)13/13, 0/23, 0/29
49056
9451
)12/12, 0/16, 0/34
26251
7778
Number of measured reflections
Unique
Final R indices
R1½I > 2rðIÞꢅ
0.0263
0.0689
0.0315
0.0759
WR2 (all reflections)
Largest difference peak/hole (e/A )
3
ꢀ
+0.74/)0.56
1.01/)1.41
[C5(CH3)5], BCH3,B2C CH3, @CCH3 not observed. 11B-
NMR: d ¼ 29 (br). 31P-NMR (C6D6, 80.9 MHz):
5. Supplementary material
1
d ¼ 11:1 (t, JPH ¼ 341.7 Hz, PH2).
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been de-
posited with the Cambridge Crystallographic Data
Centre, CCDC No. 219133 for compound 4 and CCDC
No. 219134 for compound 7. Copies of this information
may be obtained free of charge from the Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
(fax: +44-1223-336-033; e-mail: deposit@ccdc.cam.
ac.uk or http://www.ccdc.cam.ac.uk).
4.10. (g5-Pentamethyl-2,3-dihydro-1,3-diborolyl)(g5-pen-
tamethylcyclopentadienyl)-ruthenium-trimethylphosphane
(12c)
Trimethylphosphane (20 mg, 0.26 mmol) was added
dropwise to a solution of 1 (90 mg, 0.24 mmol) in 5 ml of
toluene at 0 °C. The colour changed reversibly from vi-
olet to orange. The product could not be isolated. NMR
studies of the yellow solution: 11B-NMR: d ¼ 27. 31P-
NMR (C6D6,80.9 MHz): d ¼ ꢁ48:8.
Acknowledgements
We thank the Deutsche Forschungsgemeinschaft
€
4.11. Crystal structure determination for 4 and 7
(SFB 247), the Land Baden-Wurttemberg, and the
Fonds der Chemischen Industrie for support of this
work and Prof. U. Zenneck (Erlangen) for supplying
PBCtBu.
Diffraction data were collected on a Bruker-AXS
SMART 1000 (Mo Ka radiation, graphite monochro-
mator) in the x-scan mode. Crystal data and details of
the measurements are summarized in Table 3. The
structures were solved by direct methods (SHELXS86)
and refined by full-matrix least-squares methods
(SHELXL93) based on F 2 with all reflections. Non-hy-
drogen atoms were refined anisotropically, hydrogen
atoms were located in difference Fourier syntheses and
refined isotropically. 7 crystallizes with one hexane
molecule.
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