Hydroxy- and boronic-acid-functionalized carbosilanes: Synthesis and solid state structure of Si(C6H4-4-SiMe2((CH 2)3OH))4

Article abstract of DOI:10.1016/j.jorganchem.2011.01.006

Consecutive synthesis methodologies for the preparation of carbosilanes (Ph)(Me)Si((CH₂)₃B(OH)₂)₂ (2), Si(C₆H₄-4-SiMe₂((CH₂) ₃B(OH)₂))₄ (5), (Ph)(Me)Si((CH ₂)₃OH)₂ (3), and Si(C₆H ₄-4-SiMe_3-n((CH₂)₃OH) _n)₄ (6a, n = 1; 6b, n = 2; 6c, n = 3) are reported. Boronic acids 2 and 5 are accessible by treatment of (Ph)(Me)Si(CH ₂CHCH₂)₂ (1) or Si(C₆H ₄-4-SiMe₂(CH₂CHCH₂))₄ (4a) with HBBr₂·SMe₂ followed by addition of water, while 3 and 6 are available by the hydroboration of 1 or Si(C₆H ₄-4-SiMe_3-n(CH₂CHCH₂) _n)₄ (4a, n = 1; 4b, n = 2; 4c, n = 3) with H ₃B·SMe₂ and subsequent oxidation with H ₂O₂. The single molecular structure of 6a in the solid state is reported. Representative is that 6a crystallized in the chiral non-centrosymmetric space group P2₁2₁2₁ forming 2D layers due to intermolecular hydrogen bond formation of the HO functionalities along the crystallographic a and c axes.

Full text of DOI:10.1016/j.jorganchem.2011.01.006

Journal of Organometallic Chemistry 696 (2011) 1409e1415
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Hydroxy- and boronic-acid-functionalized carbosilanes: Synthesis and solid state
structure of Si(C6H4-4-SiMe2((CH2)3OH))4
*
Heinrich Lang , Zakariyya Ishtaiwi, Tobias Rüffer, Robert Mothes, Bernhard Walfort
Fakultät für Naturwissenschaften, Institut für Chemie, Lehrstuhl für Anorganische Chemie, Technische Universität Chemnitz, Straße der Nationen 62, 09111 Chemnitz, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 26 October 2010
Accepted 5 January 2011
Consecutive synthesis methodologies for the preparation of carbosilanes (Ph)(Me)Si((CH2)3B(OH)2)2 (2), Si
(C6H4-4-SiMe2((CH2)3B(OH)2))4 (5), (Ph)(Me)Si((CH2)3OH)2 (3), and Si(C6H4-4-SiMe3ꢀn((CH2)3OH)n)4 (6a,
n ¼ 1; 6b, n ¼ 2; 6c, n ¼ 3) are reported. Boronic acids 2 and 5 are accessible by treatment of (Ph)(Me)Si
(CH2CH]CH2)2 (1) or Si(C6H4-4-SiMe2(CH2CH]CH2))4 (4a) with HBBr2$SMe2 followed by addition of
water, while 3 and 6 are available by the hydroboration of 1 or Si(C6H4-4-SiMe3ꢀn(CH2CH]CH2)n)4 (4a,
n ¼ 1; 4b, n ¼ 2; 4c, n ¼ 3) with H3B$SMe2 and subsequent oxidation with H2O2.
Keywords:
Carbosilane
Molecular recognition
Supramolecular chemistry
Chirality
The single molecular structure of 6a in the solid state is reported. Representative is that 6a crystallized
in the chiral non-centrosymmetric space group P212121 forming 2D layers due to intermolecular
hydrogen bond formation of the HO functionalities along the crystallographic a and c axes.
Ó 2011 Elsevier B.V. All rights reserved.
Solid state structure
1. Introduction
prepare carbosilanes of type (Ph)(Me)Si((CH2)3B(OH)2)2, Si(C6H4-4-
SiMe2((CH2)3B(OH)2))4, (Ph)(Me)Si((CH2)3OH)2, and Si(C6H4-4-
Molecular tectonics based on molecular recognition events and
their iteration is the approach dealing with the design and prepa-
ration of molecular networks in the solid state. This includes the
formation of molecular networks from molecules consisting of
multiple peripheral recognition groups, which are capable to form
revisable intermolecular forces including van-der-Waals, electro-
SiMe3ꢀn((CH2)3OH)n)4 (n ¼ 1, 2, 3), respectively.
2. Results and discussion
The synthesis methodology to prepare hydroxy- and boronic-
acid-functionalized carbosilanes was established for (Ph)(Me)Si
((CH2)3X)2 (2, X ¼ B(OH)2; 3, X ¼ OH) using (Ph)(Me)Si(CH2CH]
CH2)2 (1) and HBBr2$SMe2/H2O or H3B$SMe2/H2O2 as key starting
materials (Scheme 1).
Hydroboration of 1 with HBBr2$SMe2 in boiling dichloro-
methane gave (Ph)(Me)Si((CH2)3BBr2)2 which by subsequent
treatment with water at 0 ꢁC produced the boronic acid (Ph)(Me)Si
((CH2)3B(OH)2)2 (2) in very good yield (Scheme 1, Experimental
Part) [5]. After appropriate work-up, carbosilane 2 could be isolated
as a colorless solid which only dissolves in common polar solvents
including tetrahydrofuran and diethyl ether. For the synthesis of 3,
carbosilane 1 was added to a tetrahydrofuran solution containing
H3B$SMe2 at 0 ꢁC. In-situ formed (Ph)(Me)Si((CH2)3BH2)2 was
thereafter oxidized with hydrogen peroxide to afford colorless
liquid 3 in 91% isolated yield [6].
static and pep interactions, as well as hydrogen and coordination
bonds affording diverse connectivities and topologies, respectively
[1e3]. Possible molecular tectons are, for example, M(C6H4-4-B
(OH)2)4 (M ¼ C, Si) and Si(C6H4-4-OH)4, which build open
3-dimensional structures with significant internal volumes for the
inclusion of guest molecules [3].
Optically inactive molecules can induce crystallization into
a chiral crystal structure [4]. Matsuura and others reported about
the probability to generate chirality in the crystallization of achiral
molecules in a chiral conformer, helical arrangement and formation
of, e. g., head-to-head stacking columnar arrangements [4].
Against this background, we recently got interested in the
synthesis of molecular network packing structures by molecular
recognition processes including hydrogen-bond formation of car-
bosilanes featuring terminal hydroxy or boronic acid functional-
ities. We here report on subsequent synthesis procedures to
Based on these studies Si(C6H4-4-SiMe3ꢀn(CH2CH]CH2)n)4 (4a,
n
¼
1; 4b,
n
¼
2; 4c,
n
¼
3) was subjected to hydro-
borationehydrolysis and hydroborationeoxidation cycles as shown
in Scheme 2, whereby identical reaction conditions were applied as
discussed earlier (see synthesis of 2 and 3, Scheme 1). After appro-
priate work-up, carbosilane Si(C6H4-4-SiMe2((CH2)3B(OH)2))4 (5)
* Corresponding author. Tel.: þ49 (0)371 531 21210; fax: þ49 (0)371 531 21219.
E-mail address: heinrich.lang@chemie.tu-chemnitz.de (H. Lang).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.01.006

1410
H. Lang et al. / Journal of Organometallic Chemistry 696 (2011) 1409e1415
in 1 and 4ae4c appearing at 1630 cmꢀ1 disappears upon addition of
the appropriate boron HeB unit to the carbonecarbon double bond.
The terminal hydroxy functionalities in 2, 3, 5, and 6ae6c give rise to
a broad characteristic band centered at 3330 cmꢀ1. The shape of this
absorption indicates hydrogen bridge formation and hence, the
origin of a molecular network by self-assembly. For the SieC bonds
a representative frequency is observed at ca. 1250 cmꢀ1 [7]. The CeB
and BeO units present in 2 and 5 show distinctive vibrations
between 620e1270 and 1310e1380 cmꢀ1 [7] (Experimental Part).
1H and 13C{1H} NMR spectroscopy is also a favored analytical
method to show the success of the hydroboration reactions. The
representative resonance signals for the SiCH2CH]CH2 units in 1
and 4a at 1.80 (SiCH2), 4.90 (H2C¼), and 5.80 ppm (CH¼) vanish
on addition of the HBBr2$SMe2 reagent and water and new signals
at 0.68 (SiCH2CH2CH2B(OH)2), 0.76 (SiCH2CH2CH2B(OH)2), 1.40
(SiCH2CH2CH2B(OH)2), and 7.39 ppm (SiCH2CH2CH2B(OH)2) are
found for 2 and 5. The appropriate alcohols 3 and 6ae6c show new
resonances at 0.75 (SiCH2CH2CH2OH), 1.44 (SiCH2CH2CH2OH), 3.36
(SiCH2CH2CH2OH), and 4.4 ppm (SiCH2CH2CH2OH). Similar trends
are found in the 13C{1H} NMR spectra of 2, 3, 5, and 6ae6c
(Experimental Part).
Scheme 1. Synthesis of 2 and 3 from 1 and HBBr2$SMe2/H2O or H3B$SMe2/H2O2.
was isolated in quantitative yield as a colorless solid, non-soluble in
protic organic solvents. The hydroxyend-capped molecules Si(C6H4-
4-SiMe3ꢀn((CH2)3OH)n)4 (6a, n ¼ 1; 6b, n ¼ 2; 6c, n ¼ 3) were isolated
in moderate to excellent yields (Experimental Part). It has to be
emphasized that carbosilane 6a with its four terminal HO func-
tionalities dissolves in benzene, dichloromethane and diethyl ether,
while 6b containing eight end-capped hydroxy groups dissolves in
more polar solvents including tetrahydrofuran and dimethyl sulf-
oxide. Carbosilane 6c with its twelve terminal hydroxy units is only
sparely soluble in, for example, dimethyl sulfoxide.
Identification of molecules 2, 3, 5, and 6ae6c described herein
has followed from their spectroscopic studies (IR; 1H, 13C{1H}, 29Si
{1H}, 11B{1H} (2, 5) NMR spectroscopies). Correct elemental
microanalyses were obtained for all complexes. Additionally, ESI-
TOF mass-spectrometric measurements were carried out. The
structure of 6a in the solid state was determined by single X-ray
structure determination.
29Si{1H} NMR spectroscopic measurements were carried out
with all newly synthesized compounds. For example, the spectrum
of carbosilane 4a shows two signals at ꢀ14.6 and ꢀ4.4 ppm which
can be assigned to the core silicon atom and the outer silicons
(Experimental Part) [8]. For 5a and 6ae6c the resonance signal for
the inner Si atom appears at the same chemical shift (ꢀ15.5 ppm).
In contrast, the outer silicons of these molecules are observed at
lower field (5, ꢀ3.5; 6b, ꢀ1.2; 6a/6c, ꢀ0.5 ppm) (Experimental Part).
The respective Si resonances for the boronic acids 2 and 5 are found
at higher field, when compared with the appropriate HO end-
capped carbosilanes 3 and 6ae6c, respectively (Experimental Part).
The formation of the boronic acid derivatives was additionally
proven by 11B{1H} NMR spectroscopy, the signal at 30 ppm is
representative for this type of units.
IR spectroscopy can be used to monitor the progress of the
hydroboration of 1 and 4 since the nC¼C vibration of the allyl group(s)
Scheme 2. Synthesis of carbosilanes 5 and 6ae6c from 4ae4c.

H. Lang et al. / Journal of Organometallic Chemistry 696 (2011) 1409e1415
1411
Furthermore, ESI-TOF mass-spectrometric measurements were
carried out with all compounds. Ionization was achieved by doping
with Kþ. Carbosilanes 3 and 6ae6c show unequivocally their molec-
ular ion peak [M þ Kþ] (Experimental Part). For 2 and 5, when
measured in tetrahydrofuran and doped with KSCN, [M þ KSCNꢀ 2H]þ
is characteristic.
The molecular structure of 6a in the solid state was determined
by single X-ray structure determination. Single crystals could be
obtained by vapor-phase diffusion of n-hexane into a dichloro-
methane solution containing 6a at ambient temperature. The
molecular structure of 6a is presented in Fig. 1 together with
selected bond distances (Å) and angles (ꢁ). Experimental and
structural refinement data are given in Table 2 (Experimental Part).
Carbosilane 6a crystallized in the non-centrosymmetric chiral
space group P212121. The chirality results from the crystallization of
achiral 6a in form of a chiral conformer, a phenomenon, which only
has been recently recognized [4a]. The absolute structure of 6a was
established by anomalous dispersion effects with respect to the
absolute structure parameter [9]. Most probably and in agreement
with the argumentation of Matsuura and Koshima, [4a] the mutual
interactions of 6a by formation of intermolecular hydrogen bonds
(Figs. 2 and 3, Table 1) are responsible for this observation. Thus, 6a
forms in the solid state 1D chains with intertectonic distances among
consecutively arranged tetrahedral silicon atoms of 7.476 Å, i. e., the
silicon atoms Si1, Si1A, Si1B and Si1C (Fig. 2). Above and below
a chain, further 1D chains of 6a are arranged, which are symmetry
generated by 21 screw axes. Within these 1D chains only one inter-
molecular interactionbetweenadjacent moleculesof6acanbefound
(Entry 4, Table 1; Fig. 2), however, between individual 1D chains
a number of different intermolecular interactions can be observed.
These intermolecular interactions are hydrogen bonds giving rise to
the formation of 2D layers of 6a along the crystallographic a and c
axes (Fig. 2). An assignment of these intermolecular hydrogen bonds
is complicated, due to the disorder of all terminal CH2CH2CH2OH
groups of 6a. The occupation factors of these disordered groups e
Fig. 2. Top-view on a selected part of one 2D layer formed by 6a in the solid state due
to intermolecular hydrogen bonds and its orientation with respect to the unit cell.
Except O-bonded hydrogen atoms, all other hydrogen atoms and the disordered CH3
groups have been omitted for clarity. Labels “A” to “G” refer to a 1st to 7th symmetry
generated molecule of 6a. Suffix ’ refers to disordered atomic positions.
although freely pre-refined with SHELXS-97 [10] e were finally
adjusted to fixed values in order to ensure that the sum of the
occupation factors of interacting OH.O units does not exceed 1.0.
In addition, O-bonded hydrogen atoms could not be located in
different Fourier maps but were added on calculated positions.
Therefore, for the assignment of intermolecular hydrogen bonds
the sum of the occupation factors of interacting OH.O atoms and
the distance criteria [11] has been taken into account. Dotted lines
between oxygen atoms indicate that both requirements are fulfilled
(Fig. 2). As shown in Fig. 2, the hydrogen atoms of interacting OH.O
units are then not always located on expected positions. Fig. 3
shows the packing mode of the 2D layers of 6a with its orienta-
tion with respect to the unit cell.
3. Conclusion
In this study, allyl-functionalized carbosilanes of type (Ph)(Me)Si
(CH2CH]CH2)2 and Si(C6H4-4-SiMe3ꢀn(CH2CH]CH2)n)4 were con-
verted to the appropriate alcohols (Ph)(Me)Si((CH2)3X)2 and Si(C6H4-
4-SiMe3ꢀn((CH2)3X)n)4 (X ¼ OH, B(OH)2; n ¼ 1, 2, 3) by hydro-
borationeoxidation or hydroborationehydrolysis cycles. The there-
fore necessary boron derivatives have been synthesized by treatment
of (Ph)(Me)Si(CH2CH]CH2)2 and Si(C6H4-4-SiMe3ꢀn(CH2CH]
CH2)n)4 with HBBr2$SMe2 and H3B$SMe2, respectively, reaction of the
appropriateBBr2 orBH2 compoundswithwaterorhydrogenperoxide
produced the respective boronic acid or alcohol-functionalized car-
bosilane species. Achiral 6a crystallized in chiral crystals in a 2D
network. The hydroxyl functionalities of 6a are responsible for the
network formation by means of intermolecular hydrogen bonds and
most probably these intermolecular contacts are responsible for the
chiral nature of the 2D network.
4. Experimental part
Fig. 1. ORTEP diagram of the molecular structure of 6a (50% probability level) with the
atom numbering scheme. Except O-bonded hydrogen atoms all hydrogen atoms and
disordered CH3 groups have been omitted for clarity. Disordered atoms have been
labeled with the suffix ‘. Selected bond distances (Å) and angles (ꢁ): Si1eC1 1.869(6),
Si1eC7 1.889(6), Si1eC13 1.870(6), Si1eC19 1.871(6); C1eSi1eC7 110.3(3),
C1eSi1eC13 108.0(3), C1eSi1eC19 111.3(2), C7eSi1eC13 110.3(3), C7eSi1eC19 106.4
(3), C13eSi1eC19 110.7(3).
4.1. General methods
All reactions were carried out under an atmosphere of purified
nitrogen (O2 traces: CuO catalyst, BASF AG, Ludwigshafen; H2O:

1412
H. Lang et al. / Journal of Organometallic Chemistry 696 (2011) 1409e1415
Fig. 3. Top (left) and side view (right) on selected parts of 2D layers formed by carbosilane 6a in the solid state. All hydrogen atoms and disordered CH3 groups are omitted for
clarity.
molecular sieve 4 Å) using standard Schlenk techniques. Tetrahy-
drofuran and diethyl ether were purified by distillation from
sodium/benzophenone ketyl; petroleum ether and dichloro-
methane from calcium hydride. Infrared spectra were recorded with
a PerkineElmer FT-IR 1000 spectrometer. 1H NMR spectra were
recorded with a Bruker spectrometer (AC 250) operating at
250.13 MHz in the Fourier transform mode; 13C{1H} NMR spectra
(1) [12] and Si(C6H4-4-SiMe3ꢀn(CH2CH]CH2)n)4 (4a, 4c) [8d] were
prepared according to synthesis methods described elsewhere.
4.2.1. Synthesis of (Ph)(Me)Si((CH2)3B(OH)2)2 (2)
To HBBr2$SMe2 dissolved in dichloromethane (11.0 mmol, 1.0 M,
11.0 mL) was drop-wise added 1 (1.01 g, 5.00 mmol) in 9.0 mL of
dichloromethane. The reaction mixture was refluxed for 2 h and
was then cooled to 0 ꢁC and carefully hydrolyzed with water
(20 mL). Stirring was continued for 30 min at ambient temperature
and then all volatile materials were removed in oil-pump vacuum.
were recorded at 50.323 MHz. Chemical shifts are reported in
d units
(parts per million) downfield from tetramethylsilane with the
solvent as the reference signal (D6-acetone/CDCl3:1H NMR,
d
¼ 2.05/
7.26 ppm; 13C{1H} NMR,
d
¼ 30.83, 205.87/77.00 ppm). 29Si{1H} NMR
spectra were recorded at 49.662 MHz (external standard relative to
Table 2
¼ 0.00 ppm); 11B{1H} NMR spectra were recorded at
Experimental data for the X-ray diffraction studies of 6a.
SiMe4,
d
80.252 MHz (external standard relative to BF3,
d
¼ 0.00 ppm). ESI-
Empirical formula
Formula weight
T (K)
C44H68O4Si5
801.42
188 (2)
TOF mass spectra were recorded with a Mariner Biospectrometry
workstation 4.0 from Applied Biosystems. Melting points were
determined using sealed nitrogen purged capillaries and a Büchi MP
510 melting point apparatus. Microanalyses were performed by the
Institute of Organic Chemistry, University Heidelberg and the
Institute of Organic Chemistry, Chemnitz, Technical University.
Crystal system
Space group
a (Ǻ)
Orthorhombic
P212121
7.4759 (5)
b (Ǻ)
23.0324 (17)
c (Ǻ)
28.278 (2)
4869.1 (6)
V (Ǻ3)
Z
4
Dcalc (g cmꢀ3
)
1.093
0.183
1736
4.2. General remarks
m
(Mo K
F (000)
Crystal size (mm)
qmin
qmax (ꢁ)
Limiting indices
a
) (mmꢀ1
)
Thestartingmaterialswerepurchasedfromcommercialproviders
and were used as received. Carbosilanes (Ph)(Me)Si(CH2CH]CH2)2
0.5 ꢂ 0.3 ꢂ 0.2
,
1.14, 25.50
ꢀ9 ꢃ h ꢃ 9; 0 ꢃ k ꢃ 27; 0 ꢃ l ꢃ 34
33276
9041 (0.1040)
99.9 (
None
334
Number of reflections collected
Number of unique reflections (Rint
Completeness to
)
Table 1
q
(%)
q
¼ 25.50ꢁ)
Selected O.O distances of crystallographically different intermolecular hydrogen
bonds of 6a.a
Absorption correction
Number of parameters
Goodness of fit (GOF) on F2
Entry
Oxygen
Oxygen on the adjacent molecule
Distance (Å)
1.023
Final R indices (I > 2(I))a
R1 ¼ 0.0936, wR2 ¼ 0.2307
R1 ¼ 0.1807, wR2 ¼ 0.2687
ꢀ0.305, 0.728
,b
1
2
3
4
5
O4C
O1’A
O4’
O4’G
O4
O3D
O3D
O2F
O1’E
O20F
2.795
2.444
2.731
2.577
2.914
R indices (all data)a
,b
Largest difference peak and hole (e Ǻꢀ3
)
P
P
a
R1
¼
kFoj ꢀ jFck= jFoj.
qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
P
P
b
wR2
¼
wðFo2 ꢀ Fc2Þ2= wðFo2Þ2 with w ¼ 1=ðs2ðFo2Þ þ ðg1PÞ2 þ g2PÞ; P ¼
a
ðmaxðFo2; 0Þ þ 2Fc2Þ=3.
Labels on the oxygen atoms refer to labels given in Fig. 2.

H. Lang et al. / Journal of Organometallic Chemistry 696 (2011) 1409e1415
1413
The product was isolated by suction filtration and washed with
distilled water (50 mL) to give 2 as a colorless solid 1.31 g
(4.46 mmol, 89% based on 1).
magnesium turnings (3.00 mol, 72.90 g) in diethyl ether (120 mL)
during 8 h. After 2 h of stirring, the Allyl magnesium bromide was
transferred via a canula from the excess of magnesium. To this
solution,1-Br-C6H4-4-SiMeCl2 (1.0 mol, 270.0 g) dissolved in diethyl
ether (200 mL) was drop-wise added during 2 h. The obtained
reaction mixture was refluxed for 5 h and then quenched with 10%
of HCl (250 mL). The organic layer was extracted with water
(200 mL), dried over magnesium sulfate, concentrated in oil-pump
vacuum and purified by fractional vacuum distillation to give 1-Br-
4-(Si(CH2CH]CH2)2Me)-C6H4 as a colorless liquid. Yield: 93.50 g
(0.33 mol, 33% based on 1-Br-C6H4-4-SiMeCl2).
M.p.: 195 ꢁC. IR (KBr): 3293 (s), 3062 (w), 2916 (m), 2876 (m),
1378 (s, BeO), 1358 (s, BeO), 1248 (m, CH3 bending), 824 (m, CeSi),
792 (m, CeSi). 1H NMR (DMSO-D6):
d
¼ 7.51 (m, 2H, C6H4), 7.38
(m, 3H, C6H4), 7.38 (bs, 4H, OH), 1.38 (m, 8H, BCH2), 0.75 (m, 8H,
CH2), 0.67 (t, 7.70 Hz, 8H, SiCH2), 0.26 (s, 24H, SiCH3). 13C{1H} NMR
(DMSO-D6):
d
¼ 139.5 (1C, Ar CeSi), 134.5 (2C, Ar CeH), 129.6 (1C,
Ar CeH) 128.6 (2, Ar CeH), 20.9 (br, 2C, BCH2), 19.8 (2C, CH2), 18.3
(4C, SiCH2), ꢀ2.1 (8C, SiCH3). 29Si{1H} NMR (DMSO-D6):
d
¼ ꢀ3.3.
11B {1H} NMR (DMSO-D6):
d
¼ 30.3. ESI-TOF-MS (THF/CH3CN/
B.p.: 93e96 ꢁC/0.5 mmHg. IR (film): 3076, 3050, 2993, 2971,
2901, 2885, 1630 (m, C]C), 1254 (m, CH3 bending), 820 (s, SieC),
KSCN): m/z 389.05 [M þ KSCN ꢀ 2H]þ. Anal. Calc. for C13H24B2O4Si
(294.16): C, 53.10; H, 8.23. Found: C, 53.24; H, 8.36.
803 (s, SieC). 1H NMR (CDCl3):
C6H4), 7.37 (dt, 8.20 Hz, 1.84 Hz, 2H, C6H4), 5.75 (m, 2H, CH2CH]
CH2), 4.89 (m, 2H, CH]CH2), 4.87 (m, 2H, CH]CH2), 1.80 (dt,
8.08 Hz, 1.15 Hz, 4H, SiCH2CH), 0.29 (s, 3H, SiCH3). 13C{1H} NMR
d
¼ 7.50 (dt, 8.20 Hz, 1.84 Hz, 2H,
4.2.2. Synthesis of (Ph)(Me)Si((CH2)3OH)2 (3)
To BH3$SMe2 (11.0 mmol, 2.0 M, 5.5 mL) in tetrahydrofuran
(50 mL), compound 1 (5.00 mmol, 1.01 g) dissolved in tetrahydro-
furan (75 mL) was added during 10 min at 0 ꢁC. After stirring the
reaction mixture at this temperature for 2 h, it was quenched with
aqueous NaOH (3 M, 3.75 mL) and was allowed to stir for another
15 min. Then H2O2 (30%, 3.75 mL) was added in a single portion and
the reaction mixture was stirred for 30 min at 25 ꢁC. Afterwards,
a saturated potassium carbonate solution (30 mL) was added.
Extraction with diethyl ether (2 ꢂ 100 mL) was carried out and the
combined organic layers were dried over brine (30 mL) and then
over magnesium sulfate. All volatiles were removed by rotary
evaporator and the obtained residue was purified by chromato-
graphy (column size: 2 ꢂ 35 cm, dichloromethane, silica gel) to
gave 3 as a colorless solid. Yield: 1.09 g (4.57 mmol, 91% based on 1).
M.p.: 237 ꢁC. IR (KBr): 3338 (s, OeH), 3068 (w), 3050 (w), 3019
(w), 2930, (s), 2873 (s), 1427 (m), 1253 (m), 1053, (s), 1012 (s), 860
(CDCl3):
d
¼ 135.6 (Ar CeSi, 1C), 135.5 (Ar CeH, 2C), 133.7 (CH2CH]
CH2, 2C), 130.9 (Ar CeH, 2C), 124.1 (Ar BreC, 1C), 114.2 (CH]CH2,
2C), 21.4 (SiCH2CH, 2C), ꢀ5.9 (SiCH3 ,1C). 29Si{1H} NMR (CDCl3):
d
¼ ꢀ5.3 (1 Si). Anal. Calc. for C13H17BrSi (281.26): C, 55.51; H, 6.09.
Found: C, 55.45; H, 6.08.
4.2.3.3. Si(C6H4-4-SiMe(CH2CH]CH2)2)4 (4b). nBuLi (2.5 M,
11.85 mmol, 4.74 mL, n-hexane) was added drop-wise to 1-Br-4-(Si
(CH2CH]CH2)2Me)-C6H4 (11.85 mmol, 3.33 g) dissolved in diethyl
ether (60 mL) at ꢀ30 ꢁC. The reaction mixture was stirred below
ꢀ10 ꢁC for 30 min and then SiCl4 (2.962, 0.5033 g, 0.339 mL) was
added in a single portion. The reaction mixture was stirred for
30 min at this temperature and then 24 h at 25 ꢁC. Afterwards, it
was quenched with water (100 mL) and the resulting mixture was
extracted with diethyl ether (100 mL). The organic layer was dried
over magnesium sulfate and all volatile materials were removed in
oil-pump vacuum. The product was purified by silica gel column
(m, CeSi), 805 (m, CeSi), 787 (m, CeSi). 1H NMR (CDCl3):
(m, 2H, C6H5), 7.34 (m, 3H, C6H5), 3.56 (t, 6.62 Hz, 4H, CH2O, 1.97
(brs, 2H, OH), 1.56 (m, 4H, CH2), 0.97 (m, 4H, CH2Si), 0.29 (s), 3H,
d
¼ 7.49
chromatography (n-hexane
e 20% dichloromethane/n-hexane,
SiCH3). 1H NMR (DMSO-D6):
C6H5), 4.43 (t, 5.30 Hz, 2H, OH), 3.36 (td, 6.72 Hz, 5.30 Hz, 4H,
CH2O), 1.43 (m, 4H, CH2), 0.74 (m, 4H, SiCH2), 0.27 (s, 24H, SiCH3).
d
¼ 7.52 (m, 2H, C6H5), 7.40 (m, 3H,
column size 4 ꢂ 25 cm) to give 4b as a colorless solid. Yield: 0.850 g
(1.020 mmol, 34% based on SiCl4).
M.p.: 235e237 ꢁC. IR (KBr): 3070, 3047, 2989, 2967, 2907, 2878,
1630 (s, C]C), 1252(m, CH3 bending), 1132, 820 (s, SieC), 805
13C{1H} NMR (CDCl3):
d
¼ 137.7 (Ar CeSi, 1C), 133.7 (Ar CeH, 2C),
129.0 (Ar CeH, 1C), 127.8 (Ar, CeH, 2C), 65.5 (CH2OH, 2C), 26.9 (CH2,
2C), 9.6 (SiCH2, 2C), ꢀ5.3 (SiCH3, 1C). 13C{1H} NMR (DMSO-D6):
(s, SieC). 1H NMR (CDCl3):
d
¼ 7.53 (m, 16H, C6H4), 5.79 (ddt,
16.86 Hz, 10.18 Hz, 8.06 Hz, 8H, CH2CH]CH2), 4.90 (ddt, 16.86 Hz,
2.76 Hz,1.50 Hz,16H, CH]CH2), 4.87 (ddt,10.10 Hz, 2.76 Hz,1.50 Hz,
8H, CH]CH2), 1.82 (dt, 8.06 Hz, 1.50 Hz, 16H, SiCH2CH), 0.29 (s, 12H,
d
¼ 138.9 (Ar CeSi, 1C), 134.5 (Ar CeH, 2C),129.8 (Ar CeH, 1C),128.7
(Ar CeH, 2C), 64.7 (CH2OH, 2C), 27.9 (CH2, 2C),10.5 (SiCH2, 2C), ꢀ4.2
(SiCH3, 1C). 29Si{1H} NMR (CDCl3):
d
¼ ꢀ1.2. 29Si{1H} NMR (DMSO-
SiCH3). 13C{1H} NMR (CDCl3):
d
¼ 138.6 (Ar CeSi, 4C),135.5 (Ar CeH,
D6):
d
¼ ꢀ1.3. ESI-TOF-MS (THF/CH3CN/KSCN): m/z 277.09 (100)
8C),134.9 (Ar CeSi, 4C),134.1 (CH2CH]CH2, 8C),133.2 (Ar CeH, 8C),
[M þ K]þ. Anal. Calc. for C13H22O2Si (238.40): C, 65.50; H, 9.30.
113.9 (CH]CH2, 8C), 21.5 (SiCH2CH, 8C), ꢀ5.9 (SiCH3 ,4C). 29Si{1H}
Found: C, 65.87; H, 9.06.
NMR (CDCl3):
d
¼ ꢀ5.8 (4 Si, Si terminal), ꢀ14.8 (1 Si, Si core). ESI-
TOF-MS (THF/CH3CN/KSCN): m/z (rel. intensity) ¼ 871.39 (100)
[M þ K]þ. Anal. Calc. for C52H68Si5 (833.52): C, 74.93; H, 8.22.
Found: C, 74.35; H, 8.24.
4.2.3. Synthesis of Si(C6H4-4-SiMe(CH2CH]CH2)2)4 (4b)
4.2.3.1. 1-Br-C6H4-4-SiMeCl2. 4-Bromophenylmagnesium bromide
was prepared by the drop-wise addition of 1,4-dibromobenzene
(1.00 mol, 236 g) dissolved in diethyl ether (600 mL) to magnesium
turnings (1.05, 25.5 g) in diethyl ether (100 mL) during 3 h. Stirring
was continued at 25 ꢁC for 17 h and afterwards the reaction mixture
was refluxed for 5 h. The Grignard solution was drop-wise added to
MeSiCl3 dissolved in diethyl ether (250 mL) over 1.5 h. The reaction
mixture was refluxed for 5 h. The solution was then transferred via
canula from the precipitated magnesium salts and the residue was
extracted with diethyl ether (3 ꢂ 100 mL). The combined fractions
were concentrated in oil-pump vacuum to give 1-Br-C6H4-4-SiMeCl2
(used without further purification).
4.2.4. Synthesis of Si(C6H4-4-SiMe2((CH2)3B(OH)2))4 (5)
To HBBr2$SMe2 dissolved in dichloromethane (1.26 mmol, 1.0 M,
1.26 mL) a dichloromethane solution (4 mL) containing 4a (0.20 g,
0.27 mmol) was drop-wise added and the reaction mixture was
refluxed for 2 h. Afterwards, the reaction solution was cooled to
0
ꢁC, hydrolyzed with water (5 mL) and stirring was continued for
30 min at ambient temperature. The organic solvent was removed
in oil-pump vacuum and the obtained solid was isolated by suction
filtration and washed with distilled water (50 mL) to give 5. Yield:
0.23 g (0.25 mmol, 92% based on 4a).
M.p.: 231 ꢁC. IR (KBr): 3368 (s), 3050 (w), 2997 (w), 2953 (m),
2922 (m), 2874 (w), 1378 (s, BeO), 1249 (m), 1133 (m), 827 (s), 804
4.2.3.2. 1-Br-4-(Si(CH2CH]CH2)2Me)-C6H4. Allyl
magnesium
bromide was prepared by slow addition of allyl bromide (2.00 mol,
242.0 g) dissolved in diethyl ether (2000 mL) to a suspension of
(m), 779 (m). 1H NMR (DMSO-D6):
7.49 (bd, 7.51 Hz, 2H, C6H4), 7.40 (bs, 4H, OeH), 1.42 (m, 8H, BCH2),
d
¼ 7.58 (bd, 7.51 Hz, 2H, C6H4),

1414
H. Lang et al. / Journal of Organometallic Chemistry 696 (2011) 1409e1415
0.76 (m, 8H, CH2), 0.68 (t, 7.60 Hz, 8H, SiCH2), 0.26 (s, 24H, SiCH3).
13C{1H} NMR (DMSO-D6):
(5 mL), 4c (0.25 g, 0.27 mmol) in tetrahydrofuran (30 mL), aqueous
NaOH (3 M, 1.44 mL), H2O2 (30%, 1.44 mL), saturated aqueous K2CO3
(15 mL), tetrahydrofuran (2 ꢂ 75 mL). After appropriate work-up,
compound 6c could be isolated as a colorless solid. Yield: 0.22 g
(0.193 mmol, 72% based on 4c).
d
¼ 142.1 (Ar CeSi, 4C), 135.9 (Ar CeH,
8C), 134.8 (Ar CeSi, 4C), 133.9 (Ar CeH, 8C), 20.9 (br, 4C, BCH2), 19.7
(CH2, 4C), 19.5 (SiCH2, 4C), ꢀ2.1 (SiCH3, 8C). 29Si{1H} NMR (DMSO-
D6):
(DMSO-D6):
d
¼ ꢀ3.5 (4 Si, Si terminal), ꢀ15.5 (1 Si, Si core). 11B{1H} NMR
d
¼ 30.1. ESI-TOF-MS (THF/CH3CN/KSCN): m/z (rel.
M.p.: 260 ꢁC. IR (KBr): 3371 (s), 3048 (w), 2997 (w), 2929 (s),
intensity) ¼ 1007.66 (100) [M þ KSCN ꢀ 2H]þ, 1021.68 (92)
[M þ THF þ K ꢀ 2H]þ. Anal. Calc. for C44H72B4O8Si5 $ H2O (930.72):
C, 56.78; H, 8.01. Found: C, 56.48; H, 7.80.
2871 (s), 1133 (s), 1053 (s), 857 (m, CeSi). 1H NMR (DMSO-D6):
d
¼ 7.57 (bd, 7.58 Hz, 8H, C6H4), 7.50 (bd, 7.58 Hz, 2H, C6H4), 4.42 (t,
5.16 Hz, 12H, OeH), 3.36 (td, 6.77 Hz, 5.16 Hz, 24H, CH2O), 1.44 (m,
24H, CH2), 0.76 (m, 24H, SiCH2). 13C{1H} NMR (CDCl3):
¼ 140.1 (Ar
CeSi), 135.9 (Ar CeH), 134.7 (Ar CeSi), 134.5 (Ar CeH), 64.8 (CH2O),
27.9 (CH2), 8.7 (SiCH2). 29Si{1H} NMR (CDCl3):
d
4.2.5. Synthesis of Si(C6H4-4-SiMe2((CH2)3OH))4 (6a)
To BH3$SMe2 (2.2 mL, 2.0 M, 4.4 mmol) dissolved in tetrahy-
drofuran (20 mL) a tetrahydrofuran solution (30 mL) containing
carbosilane 4a (0.73, 1.00 mmol) was added during 10 min at 0 ꢁC.
After 2 h of stirring, the reaction mixture was treated with aqueous
NaOH (3 M, 1.8 mL) and stirring was continued for 15 min. Then
H2O2 (30%, 1.8 mL) was added in a single portion and the reaction
mixture was stirred at 25 ꢁC for 30 min. Afterwards, a saturated
aqueous potassium carbonate solution (25 mL) was added and then
extracted with diethyl ether (2 ꢂ 75 mL). The combined organic
layers were dried over magnesium sulfate. All volatiles were
removed by rotary evaporation to give 6a as a colorless solid. Yield:
0.79 g (0.98 mmol, 98% based on 4a).
d
¼ ꢀ0.5 (4 Si, Si
terminal), ꢀ15.5 (1 Si, Si core). ESI-TOF-MS (EtOH/CH2Cl2/KSCN):
m/z 1191.14 [M þ K]þ. Anal. Calc. for C60H100O12Si5 (1153.86):
C, 62.46; H, 8.74. Found: C, 62.14; H, 8.98.
4.3. Single X-ray structure determination
Experimental crystallographic data for 6a are given in Table 2.
The data were collected with a Bruker Smart 1 k CCD diffractometer
by using graphite monochromatized Mo
K
a
radiation
(l
¼ 0.71073 Ǻ). For protection against oxygen and moisture, the
preparation of single crystals was performed in perfluoro alkyl ether
(ABCR GmbH & Co KG, viscosity 1600 cSt). The structure was solved
by direct methods with the program SHELXS-97 [10] and structure
refinement was done on least-square based F2 using SHELXL-97 [13].
All non-hydrogen atoms were fully refined anisotropically in
their local positions. The positions of the hydrogen atoms have
been refined with a riding model. All 3-hydroxypropyl substituents
are disordered and were refined on two atomic positions. In first
stages the occupation factors have been freely refined. They were
finally adjusted to idealized factors based on preliminary obtained
values. The differences are thus less than 5% and are as follows:
0.40/0.60 (C(28) ꢀ O(1)), 0.60/0.40 (C(32) ꢀ O(2)), 0.40/0.60 (C
(39) ꢀ O(3)), 0.60/0.40 (C(42) ꢀ O(4)). In addition, several methyl
groups are disordered and were refined on two atomic positions
with the following occupation factors:0.37/0.63 (C(26)) and 0.55/
0.45 (C(40), C(41)), respectively.
M.p.: 220 ꢁC. IR (KBr): 3323 (s, OeH), 3049 (w), 2998 (w), 2950
(m), 2930, (m), 2871 (m), 1248 (s, CH3 bending), 1133, (s), 864 (m,
CeSi), 835 (m, CeSi), 768 (m, CeSi). 1H NMR (CDCl3):
d
¼ 7.52 (m,
16H, C6H4), 3.58 (t, 6.76 Hz, 8H, CH2O), 1.57 (m, 12H, CH2 and OH),
0.75 (m, 8H, CH2Si), 0.28 (s, 24H, SiCH3). 1H NMR (DMSO-D6):
d
¼ 7.54 (d, 7.49 Hz, 8H, C6H4), 7.46 (bd, 7.49 Hz, 8H, C6H4), 4.41 (t,
5.30 Hz, 4H, OH), 3.36 (td, 6.72 Hz, 5.30 Hz, 8H, CH2O), 1.45 (m, 8H,
CH2), 0.72 (m, 8H, SiCH2), 0.26 (s, 24H, SiCH3). 13C{1H} NMR (CDCl3):
d
¼ 140.5 (Ar CeSi, 4C),135.6 (Ar CeH, 8C),134.6 (Ar CeH, 4C),132.9
(Ar CeH, 8C), 65.6 (CH2OH, 4C), 27.1 (CH2, 4C), 11.3 (SiCH2, 4C), ꢀ3.2
(SiCH3, 8C). 13C{1H} NMR (DMSO-D6):
d
¼ 141.7 (Ar CeSi, 4C), 136.0
(Ar CeH, 8C), 134.8 (Ar CeSi, 4C), 133.89 (Ar CeH, 8C), 64.6 (CH2OH,
4C), 27.9 (CH2, 4C), 11.9 (SiCH2, 4C), ꢀ2.2 (SiCH3, 8C). 29Si{1H} NMR
(CDCl3):
NMR (DMSO-D6):
d
¼ ꢀ2.4 (4 Si, Si terminal), ꢀ14.9 (1 Si, Si core). 29Si{1H}
d
¼ ꢀ2.5 (4 Si, Si terminal), ꢀ15.4 (1 Si, Si core).
ESI-TOF-MS (THF): m/z 839.51 [M
þ
K]þ. Anal. Calc. for
C44H68O4Si5: C, 65.94; H, 8.55. Found: C, 65.68; H, 8.72.
Acknowledgement
4.2.6. Syntheis of Si(C6H4-4-SiMe((CH2)3OH)2)4 (6b)
We are grateful to the Deutsche Forschungsgemeinschaft and
Compound 6b was synthesized in a similar manner as 6a (see
above) with following details: BH3$SMe2 (2.64 mmol, 2.0 M,
1.32 mL) dissolved in tetrahydrofuran (5 mL), carbosilane 4b
(0.30 mmol, 0.25 g) dissolved in tetrahydrofuran (20 mL), aqueous
NaOH (3 M, 1.08 mL), H2O2 (30%, 1.8 mL), saturated aqueous K2CO3
(15 mL) and diethyl ether (25 mL). After appropriate work-up,
compound 6b could be isolated as a colorless solid. Yield: 0.24 g
(0.25 mmol, 82% based on 4b).
the Fonds der Chemischen Industrie for financial support.
Supplementary material
The crystallographic data for 6a have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publi-
cation under the CCDC number 761190. They can be obtained free of
charge from the Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
M.p.: 241 ꢁC. IR (KBr): 3337 (s, OH), 3049 (w), 2996 (w), 2928 (s),
2870 (s), 1252 (m), 1133 (s), 1051 (s), 860 (m), 802 (s), 782 (s). 1H
NMR (DMSO-D6):
8H, C6H4), 4.42 (t, 5.20 Hz, 8H, OeH), 3.37 (td, 6.68 Hz, 5.20 Hz, 16H,
d
¼ 7.58 (bd, 7.42 Hz, 8H, C6H4), 7.50 (bd, 7.42 Hz,
References
CH2O), 1.45 (m, 16H, CH2), 0.75 (m, 16H, SiCH2), 0.27 (s, 12H, SiCH3).
[1] For example: (a) M.W. Hosseini, Acc. Chem. Res. 38 (2005) 313e323;
(b) J.D. Wuest, Chem. Commun. (2005) 5830e5837;
13C{1H} NMR (DMSO-D6):
d
¼ 140.9 (Ar CeSi, 4C), 135.9 (Ar CeH,
(c) M.W. Hosseini, Cryst. Eng. Comm. 6 (2004) 318e322;
(d) M. Du, Z.-H. Zhang, L.-F. Tang, X.-G. Wang, X.-J. Zhao, S.R. Batten, Chem.
Eur. J. 13 (2007) 2578e2586.
8C), 134.8 (Ar CeSi, 4C), 134.2 (Ar CeH, 8C), 64.7 (CH2O, 8C), 27.9
(CH2, 8C), 10.4 (SiCH2, 8C), ꢀ4.3 (SiCH3, 4C). 29Si{1H} NMR (CDCl3):
[2] (a) D. Laliberté, T. Maris, J.D. Wuest, Can. J. Chem. 82 (2004) 386e398;
(b) J.-H. Fournier, T. Maris, J.D. Wuest, J. Org. Chem. 69 (2004) 1762e1775;
(c) H. Sauriat-Dorizon, T. Maris, J.D. Wuest, J. Org. Chem. 68 (2003) 240e246;
(d) O. Saied, T. Maris, J.D. Wuest, J. Am. Chem. Soc. 123 (2003) 14956e14957;
(e) D. Boils, M.-E. Perron, F. Monchamp, H. Duval, T. Maris, J.D. Wuest,
Macromolecules 37 (2004) 7351e7357;
d
¼ ꢀ1.2 (4 Si, Si terminal), ꢀ15.5 (1 Si, Si core). ESI-TOF-MS (CH2Cl2/
CH3CN/KSCN): m/z 1015.50 [M þ K]þ. Anal. Calc. for C52H84O8Si5
(977.65): C, 63.88; H, 8.66. Found: C, 63.55; H, 8.89.
4.2.7. Synhesis of Si(C6H4-4-Si((CH2)3OH)3)4 (6c)
Compound 6c was synthesized as described earlier (see prepara-
tion of 6a): BH3$SMe2 (3.53 mmol, 2.0 M,1.76 mL) in tetrahydrofuran
(f) N. Malek, T. Maris, M. Simard, J.D. Wuest, J. Am. Chem. Soc. 127 (2005)
5910e5916;
(g) D. Laliberté, T. Maris, J.D. Wuest, J. Org. Chem. 69 (2004) 1776e1787.

H. Lang et al. / Journal of Organometallic Chemistry 696 (2011) 1409e1415
1415
[3] (a) J.-H. Fournier, T. Maris, J.D. Wuest, W. Guo, E. Galoppini, J. Am. Chem. Soc.
125 (2003) 1002e1006;
P. Wijkens, D.M. Grove, G. van Koten, Nature 372 (1994) 659e663;
(c) A.W. Kleij, R.A. Gossage, R.J.M. Klein Gebbink, N. Brinkmann, E.J. Reijerse,
U. Kragl, M. Lutz, A.L. Spek, G. van Koten, J. Am. Chem. Soc. 122 (2000)
12112e12124;
(b) J.-H. Fournier, T. Maris, M. Simard, J.D. Wuest, Cryst. Growth Des. 3 (2003)
535e540.
[4] (a) T. Matsuura, H. Koshima, J. Photochem. Photobiol. C 6 (2005) 7e24 (and
references cited therein);
(d) M. Wander, P.J.C. Hausoul, L.A.J.M. Sliedregt, B.J. van Steen, G. van Koten,
R.J.M. Klein Gebbink, Organometallics 28 (2009) 4406e4415;
(e) H. Lang, B. Lühmann, Adv. Mater. 13 (2001) 1523e1540 (and references
cited therein);
(b) M. Akazome, S. Suzuki, Y. Shimizu, K. Henmi, K. Ogura, J. Org. Chem. 65
(2000) 6917e6921;
(c) H. Koshima, T. Nakagawa, T. Matsuura, H. Miyamoto, F. Toda, J. Org. Chem.
62 (1997) 6322e6325;
(f) H. Lang, B. Lühmann, R. Buschbeck, J. Organomet. Chem. 689 (2004)
3598e3603;
(d) H. Koshima, K. Ding, Y. Chisaka, T. Matsuura, J. Am. Chem. Soc. 118 (1996)
12059e12065;
(g) R. Buschbeck, S. Mecklenburg, B. Lühmann, V.K. Gupta, H. Lang, Synthesis
(2004) 2727e2735;
(e) K. Tanaka, D. Fujimoto, A. Altreuther, T. Oeser, H. Irngartinger, F. Toda,
J. Chem. Soc. Perkin Trans. 2 (2000) 2115e2120;
(f) K. Tanaka, D. Fujimoto, T. Oeser, H. Irngartinger, F. Toda, Chem. Commun.
(2000) 413e414;
(h) K.C.K. Swamy, V. Chandrasekhar, J.J. Harland, J.M. Holmes, R.O. Day,
R.R. Holmes, J. Am. Chem. Soc. 112 (1990) 2341e2348.
[9] H.D. Flack, Acta Crystallogr. Sect. A: Found. Crystallogr. 39 (1983) 876e881.
[10] G.M. Sheldrick, Acta Crystallogr. Sect. A. Found. Crystallogr. 46 (1990)
467e473.
[11] G.A. Jeffrey, An Introduction to Hydrogen Bonding. Oxford University Press,
1997.
[12] (a) L.D. Nasiak, H.W. Post, J. Org. Chem. 24 (1959) 489e492. Further synthesis
procedures see:
(g) F. Toda, Cryst. Eng. Comm. 4 (2002) 215e222;
(h) R. Horikoshi, M. Mikuriya, Cryst. Growth Des. (2005) 223e230.
[5] M. Lee, Y.-S. Jeong, B.-K. Cho, N.-K. Oh, W.-C. Zin, Chem. Eur. J. 8 (2002)
876e883.
[6] H.C. Brown, S.V. Kulkarni, V.V. Khanna, V.D. Patil, U.S. Racherla, J. Org. Chem.
57 (1992) 6173e6177.
[7] G. Socrates, Infrared Characteristic Group Frequencies. John Wiley & Sons,
1980, p126.
[8] For example: (a) S.-H. Hwang, C.D. Shreiner, C.N. Moorefield, G.R. Newkome,
New J. Chem. 31 (2007) 1192e1217 (and references cited therein);
(b) J.W.J. Knapen, A.W. van der Made, J.C. de Wilde, P.W.N.M. van Leeuwen,
(b) Z. Li, C. Yang, H. Zheng, H. Qui, G. Lai, J. Organomet. Chem. 693 (2008)
3771e3779;
(c) Z. Li, X. Cao, G. Lai, J. Liu, Y. Ni, J. Wu, H. Qui, J. Organomet. Chem. 691
(2006) 4740e4746.
[13] G.M. Sheldrick, SHELX-97, Program for Crystal Structure Refinement.
University of Göttingen, Göttingen, Germany, 1997.