Synthesis and structure of new [3]silametallocenophanes of group 8 metals

Article abstract of DOI:10.1021/om300564y

The synthesis and characterization of new [3]silametallocenophanes of the group 8 metals via salt elimination is presented. Thereby, new [3]silaferrocenophanes as well as the first [3]silametallocenophanes of the heavier metals ruthenium and osmium could be synthesized and characterized. Also, the first solid-state structure of a [3]silaferrocenophane was determined by X-ray crystallographic analysis.

Full text of DOI:10.1021/om300564y

Article
pubs.acs.org/Organometallics
Synthesis and Structure of New [3]Silametallocenophanes of Group 8
Metals
Holger Braunschweig,* Alexander Damme, Kai Hammond, and Julian Mager
Institut fur Anorganische Chemie, Julius-Maximilians-Universitat Wurzburg, Am Hubland, D-97074, Wurzburg, Germany
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* Supporting Information
ABSTRACT: The synthesis and characterization of new [3]silametallocenophanes of the group 8 metals via salt elimination is
presented. Thereby, new [3]silaferrocenophanes as well as the first [3]silametallocenophanes of the heavier metals ruthenium
and osmium could be synthesized and characterized. Also, the first solid-state structure of a [3]silaferrocenophane was
determined by X-ray crystallographic analysis.
1. INTRODUCTION
Shortly after the report of the parent ferrocene as the archetypal
sandwich complex,1 a [3]carbaferrocenophane was presented in
the literature as the first example of a bridged or ansa sandwich
complex.2 Over the past two decades, ferrocenophanes have
been widely studied, in particular with respect to their
propensity to undergo ring-opening polymerization with
Figure 1. Known trisilaferrocenophanes 1 and 2.
formation of well-defined organometallic polymers.3 Recent
years have brought about significant developments in the
chemistry of non-iron metallocenophanes,3c extending the
Although [3]silaferrocenophanes 1 and 2 have been known
scope of this important class of compounds to transition metals
such as Ti,4 V,5 Cr,6 Mn,7 Co,8 and Ni.9 However, as far as
in the literature since 1972, no single-crystal X-ray molecular
iron’s higher homologues are concerned, ruthenocenophanes10
structure has been reported. In this paper we report the
are less prolific and only a few osmocenophanes11 have been
synthesis of new [3]silaferrocenophanes as well as the first
synthesis of [3]silaruthenocenophanes and [3]-
osmocenophanes.
reported. Although the aforementioned [3]-
carbaferrocenophane may be considered the ancestor of ansa
sandwich complexes, corresponding homonuclear [3]-
2. RESULTS AND DISCUSSION
metallocenophanes of group 8 metals are rare. While [3]thia-
Using a modification of the synthetic route of Russell et al.,15
three diphenyltrisilanes and the three corresponding dichloro-
trisilanes were synthesized. The substituents at the central
silicon atom were introduced by reacting lithiated phenyl-
dimethylsilane with different dichlorodialkylsilanes. The known
synthesis was improved by using lithium sand instead of lithium
wire, furnishing the trisilanes 5−7 in yields up to 90%. The 1,3-
dichlorotrisilanes Et2Si(SiMe2Cl)2 (8), iPr2Si(SiMe2Cl)2 (9),
and tBuMeSi(SiMe2Cl)2 (10) were obtained in moderate to
bridged representatives are known for the whole triad,11a
[3]carba-bridged derivatives have been reported for ferro- and
ruthenocenophanes2,12 and [3]sila bridges are exclusively
]
known for iron (compounds 1 and 2, Figure 1).13,14
The latter compounds date back to an initial report by
Kumada et al. in 1972, in which the 1,1′-dilithioferrocene−
tmeda adduct 3 and dichlorohexamethyltrisilane were em-
ployed in a salt metathesis reaction to provide 1 as an orange
oil.13 An alternative protocol was reported by Marschner et al.
in 2006,14 involving treatment of the 1,1′-disilaferrocene 4 with
potassium and Me2SiCl2 to yield 2 as an orange powder.
Scheme 1 shows the two different reaction pathways.
Received: June 21, 2012
Published: August 13, 2012
© 2012 American Chemical Society
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Scheme 1. Reaction Pathways to Trisila-Bridged Ferrocenophanes
Scheme 2. Synthesis of the Diphenyl- and Dichlorotrisilanes
good yields by reacting the 1,3-diphenyltrisilanes with acetyl
chloride and aluminum trichloride in hexane (Scheme 2).
The multinuclear NMR spectroscopic data of 6 and 9 agree
with those previously reported for these compounds, while all
data obtained for the new species 5, 7, 8, and 10 fulfill our
expectations and require no further discussion.
In order to prepare ferrocenophanes, we reacted [Fe(η5-
C5H4Li)2]·tmeda (3; tmeda = N,N,N′,N′-tetramethylethylene-
diamine) with the 1,3-dichlorotrisilanes 8−10 in metathesis
reactions. The novel compound 11 was obtained as a dark
1
orange oil in 51% yield (Figure 2). The H NMR spectrum in
Figure 3. Two views of the molecular structure of 13 in the crystal
(ellipsoids depicted at the 50% probability level). Hydrogen atoms are
omitted for clarity. Selected bond lengths (Å) and angles (deg): Si1−
Si2 = 2.3581(7), Si2−Si3 = 2.3575(8), Si1−Cipso = 1.867(2), Si3−
C′ipso = 1.872(2), Si1−CMe = 1.877(2) and 1.886(2), Si3−C′Me
=
1.878(2) and 1.879(2), Si2−CiPr = 1.908(2) and 1.911(2); Si1−Si2−
Si3 = 104.66(3), Cipso−Si1−Si2 = 113.37(5), C′ipso−Si3−Si2 =
113.49(6).
Figure 2. Novel trisilaferrocenophanes 11−13.
signals at 0.42 and 0.41 ppm, respectively. Finally, the signals of
the three methyl protons at the central silicon atom were found
at 0.30 ppm. The 29Si NMR spectrum exhibits a pattern similar
to that of 11, showing a signal at −21.50 ppm for the dimethyl-
substituted silicon atoms and at −23.05 ppm for the tert-
butylmethyl-substituted silicon center.
C6D6 shows two signals for the Cp protons at 4.18 and 4.06
ppm as well as a triplet signal at 1.16 ppm and a multiplet signal
at 0.94 ppm for the ethyl protons and a singlet signal at 0.33
ppm for the methyl groups. The signals indicate an integration
ratio of 4:4:6:4:12. The signals of the silicon atoms attached to
the Cp rings can be detected in the 29Si NMR signal at −21.24
ppm, while the signal for the central silicon nucleus appears at
−19.13 ppm.
In contrast to the oily product 11, the (tert-butyl)methyl- and
diisopropyl-substituted compounds 12 and 13 were obtained as
orange powders in 41% and 30% yields. Crystals suitable for a
single-crystal X-ray crystallographic analysis of 13 were grown
from pentane (Figure 3).
The two different substituents at the central silicon atom in
12 reduce the overall symmetry of the molecule, which leads to
further splitting of the proton resonances of the Cp rings. In the
1H NMR spectrum two signals appear at 4.18 and 4.16 ppm
that integrate to two protons each and a third signal at 4.03
ppm that integrates to four protons. The former two
resonances can presumably be ascribed to the protons in a
position α to the trisila bridge. Additionally, the nine tert-butyl
protons result in a signal at 1.11 ppm, while the diastereotopic
methyl groups of the SiMe2 moieties display two independent
1
The H NMR of 13 shows two multiplet signals at 4.18 and
4.08 ppm for the cyclopentadienyl protons, as well as a septet
signal at 1.20 and a doublet signal at 1.28 ppm for the isopropyl
groups, respectively, and a singlet at 0.40 ppm for the methyl
groups. The separation of the Cp proton resonances observed
for these species is much smaller than in similar systems, for
instance the highly distorted [1]boraferrocenophanes,17 thus
indicating significantly less strained molecular structures.
Further proof for this assumption is provided by the results
of the X-ray crystallographic analyses.
Complex 13 crystallizes in the orthorhombic space group
Pna21. With a relatively small tilt angle α of −4.9°, the ipso
carbon atoms are slightly bent away from the iron center and
Cp rings deviate little from a mutually parallel orientation. In
particular, the latter finding indicates that the [3]-
silaferrocenophane 13 adopts the typical structure of a
nonstrained ansa complex.2a The outer silicon atoms are
slightly bent out of the plane of their corresponding
cyclopentadienyl rings (5.3°). The ring−ring distance (3.297
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Å) and the silicon−silicon distances (2.357(1) and 2.358(1) Å)
are similar to those of the tetramethyl[2]silaferrocenophane.16
Subsequently, this protocol was successfully extended to the
heavier group 8 metals. In our studies we observed that the
1,1′-dilithio-substituted ruthenocene and osmocene can be
prepared in higher yields when the lithiation is carried out in
the presence of pmdta (pmdta = N,N,N′,N′,N″-pentamethyl-
diethylenetriamine) rather than the commonly employed
tmeda (vide supra). Therefore, ruthenocene and osmocene
were suspended in pentane, and pmdta was added
subsequently. After a few minutes, n-butyllithium was added
to the suspension and the mixture was stirred overnight to give
off-white dilithium salts. The 1,1′-dilithioruthenocene 14 and
the 1,1′-dilithioosmocene 15 are air- and moisture-sensitive
solids but can be stored under an argon atmosphere at room
temperature without signs of decomposition. These species
were added to the trisilane 9, dissolved in an aromatic or
aliphatic solvent, and the resulting suspension was stirred for 1
day at ambient temperature to give the first trisilaruthenoce-
nophane and the first trisilaosmocenophane complexes after
workup in yields of 42% (16) and 32% (17) as light brown oils
(Figure 4).
dilithioosmocene−pmdta adduct 15 have been synthesized and
used as starting materials for synthesis of the first trisila-bridged
ruthenocenophane 16 and osmocenophane 17.
4. EXPERIMENTAL SECTION
All experiments were performed under an inert atmosphere of dry
argon using standard Schlenk techniques or in a glovebox. Solvents
were dried according to standard procedures, freshly distilled prior to
use, degassed, and stored under argon over activated molecular sieves
(4 Å). Deuterated solvents were degassed by three freeze−pump−
thaw cycles and stored over molecular sieves. The starting material
[Fe(η5-C5H4Li)2·tmeda] (3) was prepared according to published
methods; [Ru(η5-C5H5)2] and [Os(η5-C5H5)2] were purchased from
ABCR and used without further purification. All other compounds
were obtained commercially and used without further purification.
NMR spectra were recorded on a Bruker AMX 400 or a Bruker
1
Avance 500 NMR spectrometer. H and 13C{1H} NMR spectra were
referenced to external TMS via the residual protio solvent (1H) or the
solvent itself (13C). 29Si{1H} NMR spectra were referenced to external
1
TMS. Assignments were made from the analysis of H,13C-HMQC
and 1H,1H-COSY NMR spectroscopic experiments. All chemical shifts
are reported in ppm. Elemental analyses were performed on a Vario
Micro Cube (Elementar Analysensysteme GmbH) or a CHNS-932
(Leco) elemental analyzer.
Et2Si(PhMe2Si)2 (5). Into a suspension of 0.907 g (13.2 mmol) of
powdered lithium in 40 mL of thf at 0 °C, 10.87 g (63.7 mmol) of
PhMe2SiCl was dropped over the course of 1 h. After 2 days at
ambient temperature the unreacted lithium was removed over Celite,
the remaining solution was cooled to 0 °C, and 5.00 g (31.8 mmol) of
Et2SiCl2 in 20 mL of thf was added at 0 °C. After 1 day at room
temperature the solvent was removed, the residue was dissolved in 40
mL of hexane, and the salts were removed by filtration. After
distillation at 115 °C under high vacuum, 5 was obtained as a colorless
liquid in 72% yield (8.26 g, 23.2 mmol).
Figure 4. Trisilaruthenocenophane 16 and trisilaosmocenophane 17.
1H NMR (501 MHz, CD2Cl2, 297 K): δ 7.37 (m, 4H, C6H5), 7.28
(m, 6H, C6H5), 0.94 (m, 6H, Et), 0.75 (m, 4H, Et), 0.31 (s, 12H, Me).
13C{1H} NMR (126 MHz, CD2Cl2, 297 K): δ 140.72, 134.25, 128.60,
128.02, 10.18, 2.61, −1.77. 29Si{1H} NMR (99 MHz, CD2Cl2, 297 K):
δ −19.0, −37.4. Anal. Calcd for C20H32Si3 (356.73): C, 67.34; H, 9.04.
Found: C, 67.05; H, 8.65.
While the oily consistency of the new [3]-
silametallocenophanes prevented their characterization by X-
ray crystallographic analyses, their structure in solution was
unambiguously derived from multinuclear NMR spectroscopy.
1
Et2Si(Me2SiCl)2 (8). A solution of 8.26 g (23.2 mmol) 5 in 75 mL
of hexane was reacted with 4.54 g (57.9 mmol) of acetyl chloride at
−78 °C. Afterward 7.72 g (57.9 mmol) of AlCl3 was added and the
reaction mixture was warmed to room temperature. After 16 h the
solution was filtered and the hexane was removed. Distillation at 75 °C
under high vacuum yielded 5.70 g (20.8 mmol, 90%) of 8 as a colorless
liquid.
In the H NMR spectrum, the trisilaruthenocenophane 16
shows two signals for the Cp protons at 4.62 and 4.47 ppm, a
septet at 1.34 ppm and a multiplet at 1.22 ppm for the iPr
protons, and a singlet at 0.40 ppm for the methyl protons. The
osmocenophane 17 shows signals at 4.62, 4.48, 1.36, 1.23, and
0.40 ppm which are similar to those of 16. The signals of both
compounds integrate to 4:4:2:12:12. The rather small
separation of the Cp signals by 0.15 ppm can be compared
to the separation of the Cp protons in 13 (0.10 ppm) and
indicates a rather small strain of the bridge. While the signals in
the 29Si NMR spectrum for the outer silicon atom (−20.8 ppm
for 16 and −20.9 ppm for 17) are similar to the corresponding
signals in 13 (−21.0 ppm), the signals for the central silicon
atoms (−12.2 ppm (16) and −12.4 ppm (17)) show an upfield
shift of more than 5 ppm with respect to that for the
corresponding ferrocenophane 13 (−17.5 ppm).
1H NMR (501 MHz, CDCl3, 297 K): δ 1.10 (m, 6H, Et), 0.93 (m,
4H, Et), 0.59 (m, 12H, Me). 13C{1H} NMR (126 MHz, CD2Cl2, 297
K): δ 9.78, 4.55, 1.54. 29Si{1H} NMR (99 MHz, CD2Cl2, 297 K): δ
−25.6, −34.0. Anal. Calcd for C8H22Cl2Si3 (273.42): C, 35.14; H, 8.11.
Found: C, 34.90; H, 8.01.
iPr2Si(PhMe2Si)2 (6). A suspension of 0.850 g (12.5 mmol) of
powdered lithium in 40 mL of thf at 0 °C was treated with 10.0 g (58.8
mmol) of Me2PhSiCl over the course of 1 h. After it was stirred for 16
h, the suspension was filtered over Celite and added dropwise to a
solution of 5.43 g (29.4 mmol) of iPr2SiCl2 in 70 mL of thf. After
another 16 h of stirring, all volatile components were removed under
vacuum. The residue was suspended in 20 mL of hexane and filtered.
Removal of the solvent and distillation at 160 °C resulted in 10.1 g
(26.2 mmol, 90%) of 6 of a colorless oil.
3. SUMMARY
In this paper we have reported the improved synthesis of 1,3-
diphenyltrisilanes 5−7 and their conversion to the 1,3-
dichlorotrisilanes 8−10. Their reaction with a 1,1′-dilithiofer-
rocene−tmeda adduct (3) led to the trisila-bridged ferroceno-
phanes 11−13. Compound 13 was crystallographically
characterized to give the first solid-state molecular structure
of a trisilaferrocenophane. The pmdta adduct of 1,1′-
dilithioruthenocene−pmdta adduct 14 as well as the 1,1′-
1H NMR (500 MHz, CD2Cl2, 297 K): δ 7.34 (m, 4H, C6H5), 7.22
(m, 6H, C6H5), 1.16 (sept, 3J = 7.7 Hz, 2H, iPr), 0.93 (d, 12H, 3J = 7.7
Hz, iPr), 0.34 (s, 12H, Me). 13C{1H} NMR (126 MHz, CD2Cl2, 297
K): δ 140.96, 134.32, 128.42, 127.82, 21.06, 12.78, 0.04. 29Si{1H}
NMR (99 MHz, CD2Cl2, 297 K): δ −19.1, −27.8. Anal. Calcd for
C22H36Si3 (384.8): C, 68.67; H, 9.43. Found: C, 68.96; H, 9.57.
iPr2Si(Me2SiCl)2 (9). A 10.79 g amount (26.2 mmol) of 6 in 60 mL
of hexane at −70 °C was first treated with 4.79 g (61.4 mmol) of acetyl
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chloride and afterward with 9.07 g (68.0 mmol) of AlCl3. After 20 h of
stirring at room temperature, the solid compounds were filtered off
and the solvent was removed under vacuum at 0 °C. After distillation
under high vacuum at 40 °C, 6.84 g (25.0 mmol, 84%) of the product
was obtained as an oily colorless solid.
removed and the residue was extracted with 10 mL of hexane. The
solvent was again removed, and the crude product was sublimed at 105
°C under high vacuum to yield 0.21 g (0.51 mmol, 30%) of an orange
powder.
1H NMR (400 MHz, C6D6, 293 K): δ 4.18 (m, 4H, C5H4), 4.08 (m,
4H, C5H4), 1.28 (sept,, 2H, 3J = 6.4 Hz, iPr), 1.20 (d, 12H, 3J = 6.4 Hz,
iPr), 0.401 (s, 12H, CH3). 13C{1H} NMR (100 MHz, C6D6, 293 K): δ
73.95, 72.22, 70.89, 22.29, 13.12, 0.75. 29Si{1H} NMR (79 MHz, C6D6,
293 K): δ −17.5, −21.0. Anal. Calcd for C20H34FeSi3 (414.59): C,
57.94; H, 8.27. Found: C, 57.51; H, 8.31.
1H NMR (500 MHz, CDCl3, 297 K): δ 1.34 (sept, 2H, 3J = 7.5 Hz,
3
iPr), 1.20 (d, 12H, J = 7.5 Hz, iPr), 0.65 (m, 12H, Me). 13C{1H}
NMR (126 MHz, CD2Cl2, 297 K): δ 20.65, 11.96, 5.89. 29Si{1H}
NMR (99 MHz, CD2Cl2, 297 K): δ 25.5, −25.5. Anal. Calcd for
C8H22Cl2Si3 (273.42): C, 35.14; H, 8.11. Found: C, 34.90; H, 8.01.
tBuMeSi(PhMe2Si)2 (7). A suspension of 0.831 g (12.2 mmol) of
powdered lithium in 40 mL of thf was added to 10.00 g (58.8 mmol)
of Me2PhSiCl at 0 °C. After 16 h at room temperature, the suspension
was filtered over Celite, cooled to 0 °C, and added dropwise to a
solution of 5.00 g (27.2 mmol) of tBuMeSiCl2 in 70 mL of thf. After
16 h the volatile compounds were removed under vacuum. Hexane
(60 mL) was added, and the solids were removed by filtration.
Kugelrohr distillation at 210 °C under high vacuum yielded 9.25 g
(25.0 mmol, 85%) of the product as a colorless liquid.
[Ru(C5H4Li)2]·pmdta (14). A suspension of 1.00 g (4.33 mmol) of
ruthenocene and 2.26 mL (10.8 mmol) of pmdta in 35 mL of pentane
was stirred for 1 h. Afterward, 6.76 mL (10.8 mmol, 1.57 M in hexane)
of n-butyllithium was added dropwise at 0 °C. After 12 h of stirring,
the solid product was collected on a glass frit, washed with 3 × 7 mL of
pentane, and dried under high vacuum. A 1.70 g amount (4.07 mmol,
94%) of a white powder was obtained.
Anal. Calcd for C19H31Li2N3Ru (417.2): C, 54.80; H, 7.50; N,
10.09. Found: C, 54.59; H, 7.44; N, 10.36.
1H NMR (500 MHz, CD2Cl2, 297 K) δ 7.392−7.422 (m, 4H,
C6H5), 7.322−7.283 (m, 6H, C6H5), 0.81 (s, 9H, tBu), 0.37 (s, 6H,
Me), 0.29 (s, 6H, Me), 0.20 (s, 3H, Me). 13C{1H} NMR (125.77
MHz, CDCl3, 297 K): δ 140.68, 134.15, 128.44, 127.83, 29.73, 20.00,
−1.31, −1.44, −8.79. 29Si{1H} NMR (99.360 MHz, CDCl3, 297 K): δ
−19.4, −31.5. Anal. Calcd for C21H34Si3 (370.2): C, 68.03; H, 9.24; Si,
22.73. Found: C, 68.14; H, 9.38.
[Ru(C5H4SiMe2)2SiiPr2] (16). In a J. Young NMR tube, 77 mg
(0.18 mmol) of 14 in 0.8 mL of C6D6 was reacted with 70 mg of
iPr2Si(Me2SiCl)2 (9; 0.18 mmol). After 1 day, all solid compounds
were removed by filtration and the solvent was removed under high
vacuum. After 3 h under high vacuum at 70 °C, 36 mg (0.078 mmol,
42%) of a light brown oil was obtained.
1H NMR (400 MHz, C6D6, 293 K): δ 4.62 (m, 4H, C5H4), 4.47 (m,
4H, C5H4), 1.34 (sept, 2H, 3J = 6.8 Hz, iPr), 1.22 (d, 12H, 3J = 6.8 Hz,
iPr), 0.396 (s, 12H, Me). 13C{1H} NMR (100 MHz, C6D6, 293 K): δ
76.07, 75.04, 72.88, 22.40, 13.32, 0.99. 29Si{1H} NMR (79 MHz, C6D6,
293 K): δ −12.2, −20.8. Anal. Calcd for C20H34RuSi3 (459.80): C,
52.24; H, 7.45. Found: C, 51.55; H, 7.72.
tBuMeSi(Me2SiCl)2 (10). A solution of 7.83 g (21.2 mmol) of 7 in
60 mL of hexane was reacted first with 3.41 mL (3.75 g, 47.8 mmol) of
acetyl chloride at −70 °C and then with 7.10 g (53.3 mmol) of AlCl3.
After the mixture was warmed to room temperature and stirred for 40
h, the solution was filtered off and the solvent was removed at 0 °C.
After distillation at 51 °C under high vacuum, 0.21 g (0.73 mmol,
20%) of 10 was obtained as a colorless liquid.
[Os(C5H4Li)2]·pmdta (15). A 0.57 g amount (1.8 mmol) of
osmocene was stirred with 0.93 mL (4.5 mmol) of pmdta in 30 mL of
pentane over the course of 1 h. Then, 2.60 mL (1.6 mmol, 1.57 M in
hexane) of n-butyllithium was added at 0 °C. After 1 h in an
ultrasound bath and 5 h of stirring, the solid compound was collected
on a frit and washed with 3 × 5 mL of pentane. After drying under
high vacuum, 0.86 g (1.7 mmol, 95%) of an off-white powder was
obtained.
1H NMR (500 MHz, CDCl3, 297 K): δ 1.10 (s, 12H, tBu), 0.61 (s,
12H, Me), 0.28 (s, 3H, Me). 13C{1H} NMR (126 MHz, CDCl3, 297
K): δ 29.45, 19.66, 5.03, 4.94, −10.08. 29Si{1H} NMR (99 MHz,
CDCl3, 297 K): δ . 25.3, −28.8. Anal. Calcd for C9H24Cl2Si3 (287.4):
C, 37.61; H, 8.42. Found: C, 38.01; H, 8.35.
[Fe(C5H4SiMe2)2SiEt2] (11). To a solution of 0.50 g (1.6 mmol) of
3 in 20 mL of thf was slowly added 0.36 g (1.3 mmol) of
Et2Si(Me2SiCl)2 (8). After 16 h, the thf was removed under high
vacuum, 20 mL of pentane was added, and the solid compounds were
removed by filtration. The pentane was removed under high vacuum
and the product purified by Kugelrohr distillation at 120 °C under
high vacuum. A 0.31 g amount (0.80 mmol, 51%) of 11 as an orange-
brown oil was obtained.
Anal. Calcd for C19H31Li2N3Os (507.2): C, 45.14; H, 6.18; N, 8.31.
Found: C, 46.06; H, 6.46; N, 8.51.
[Os(C5H4SiMe2)2SiiPr2] (17). A suspension of 0.10 g (0.29 mmol)
of 15 in 10 mL of hexane was reacted with 70 mg (0.27 mmol) of
iPr2Si(Me2SiCl)2 in 5 mL of hexane over the course of 1 h. After 28 h
of stirring, the salts and the solvent were removed and the product was
purified by sublimation of the osmocene at 100 °C under vacuum to
yield 35 mg (0.063 mmol, 19%) of a slightly brown oil.
1H NMR (400 MHz, C6D6, 293 K): δ 4.18 (m, 4H, C5H4), 4.06 (m,
3
3
4H, C5H4), 1.17 (t, 6H, J = 8.1 Hz, CH2CH3), 0.94 (q, 4H, J = 8.1
Hz, CH2CH3), 0.33 (s, 12H, Me). 13C{1H} NMR (100 MHz, C6D6,
293 K): δ 73.75, 72.34, 70.76, 10.68, 2.78, −0.94. 29Si{1H} NMR (79
MHz, C6D6, 293 K): δ −19.1, −21.2. Anal. Calcd for C18H30FeSi3
(386.53): C, 55.93; H, 7.82. Found: C, 56.80; H, 7.62.
1H NMR (400 MHz, C6D6): δ 4.62 (m, 4H, C5H4), 4.47 (m, 4H,
3
3
C5H4), 1.35 (sept, 2H, J = 6.4 Hz, iPr), 1.23 (d, 12H, J = 6.4 Hz,
iPr), 0.40 (s, 12H, Me). 13C{1H} NMR (100 MHz, C6D6): δ 75.03,
72.86, 70.43, 22.36, 13.30, 0.95. 29Si{1H} NMR (79 MHz, C6D6): δ
−12.4, −20.9. Anal. Calcd for C20H34OsSi3 (549.0): C, 43.76; H, 6.24.
Found: C, 43.81, H, 6.32.
[Fe(C5H4SiMe2)2SiMetBu] (12). A 0.25 g amount (0.73 mmol) of
3 was dissolved in 15 mL of thf and treated with 0.21 g (0.73 mmol) of
tBuMeSi(Me2SiCl)2 (10) over the course of 1 h. After 16 h, the
solvent was removed under high vacuum, the residue was treated with
10 mL of hexane, and the solid compounds were removed by filtration.
After removal of the solvent, the product was purified by column
chromatography on silica using hexane to give 0.12 mg (0.30 mmol,
41%) of an orange powder.
Crystal Structure Determination. The crystal data of 13 were
collected on a Bruker X8-APEX II diffractometer with a CCD area
detector and multilayer mirror monochromated Mo Kα radiation. The
structure was solved using direct methods, refined with the Shelx
software package, and expanded using Fourier techniques.18 All non-
hydrogen atoms were refined anisotropically. Hydrogen atoms were
included in structure factor calculations. All hydrogen atoms were
assigned to idealized geometric positions.
1H NMR (400 MHz, C6D6, 293 K): δ 4.18 (m, 2H, C5H4), 4.16 (m,
2H, C5H4), 4.04 (m, 4H, C5H4), 1.11 (s, 9H, tBu), 0.42 (s, 6H, Me),
0.41 (s, 3H, Me), 0.30 (s, 6H, Me). 13C{1H} NMR (100 MHz, C6D6,
293 K): δ 74.25, 73.31, 71.67, 71.38, 70.31, 30.12, 20.07, 0.03, −0.73,
−8.58. 29Si{1H} NMR (79 MHz, C6D6, 293 K): δ −21.5, −23.1. Anal.
Calcd for C19H32FeSi3 (400.60): C, 56.97; H, 8.05. Found: C, 57.29;
H, 8.16.
Crystal data for 13: C20H34FeSi3, Mr = 414.59, yellow block, 0.496 ×
0.407 × 0.222 mm3, orthorhombic, space group Pna21, a = 18.704(5)
Å, b = 13.274(4) Å, c = 8.821(4) Å, V = 2190.1(13) Å3, Z = 4, ρcalcd
=
1.257 g cm−3, μ = 0.853 mm−1, F(000) = 888, T = 100(2) K, R1 =
0.0169, wR2 = 0.0438, 4269 independent reflections (2θ ≤ 5212°),
225 parameters.
[Fe(C5H4SiMe2)2SiiPr2] (13). A solution of 0.44 g (1.5 mmol)
iPr2Si(Me2SiCl)2 in 5 mL of thf was added to a solution of 0.55 g (1.8
mmol) of 3 in 15 mL of thf at 0 °C. After 16 h the solvent was
Crystallographic data have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication no.
CCDC-887330. These data can be obtained free of charge from
6320
dx.doi.org/10.1021/om300564y | Organometallics 2012, 31, 6317−6321

Organometallics
Article
The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.
uk/data_request/cif.
(10) (a) Herberhold, M.; Baertl, T. Z. Naturforsch., B: Chem. Sci.
1995, 50, 1692−1698. (b) Vogel, U.; Lough, A. J.; Manners, I. Angew.
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Lund, C. L.; Quail, J. W.; Rehahn, M.; Muller, J. Organometallics 2007,
̈
ASSOCIATED CONTENT
* Supporting Information
■
26, 4658−4662. (d) Bagh, B.; Schatte, G.; Green, J. C.; Muller, J. J.
̈
S
Am. Chem. Soc. 2012, 134, 7924−7936.
A CIF file giving X-ray diffraction data for 13 and figures giving
1H NMR spectra of 11 and 12. This material is available free of
charge via the Internet at http://pubs.acs.org.
(11) (a) Abel, E. W.; Long, N. J.; Orrell, K. G.; Osborne, A. G.; Sik,
V. J. Organomet. Chem. 1991, 419, 375−382. (b) Gusev, O. V.; Kalsin,
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M.; Vologdin, N. V.; Petrovskii, P. V.; Lyssenko, K. A.; Tsvetkov, A. V.;
Beletskaya, I. P. Organometallics 2006, 25, 2750−2760. (e) Martinak,
S. L.; Sites, L. A.; Kolb, A. J.; Bocage, K. M.; McNamara, W. R.;
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AUTHOR INFORMATION
Corresponding Author
*Tel: (+49) 931-31-85260. Fax: (+49) 931-31-84623. E-mail:
h.braunschweig@uni-wuerzburg.de.
■
Notes
The authors declare no competing financial interest.
(12) (a) Kamiyama, S.; Suzuki, T. M.; Kimura, T.; Kasahara, A. Bull.
Chem. Soc. Jpn. 1978, 51, 909−912. (b) Ohba, S.; Saito, Y.; Kamiyama,
S.; Kasahara, A. Acta Crystallogr., Sect. C 1984, 40, 53−55.
(13) Kumada, M.; Kondo, T.; Mimura, K.; Ishikawa, M.; Yamamoto,
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(14) Wagner, H.; Baumgartner, J.; Marschner, C. Organometallics
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ACKNOWLEDGMENTS
We thank the Deutsche Forschungsgemeinschaft (DFG) for
financial support.
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