Synthesis of 4-silaspiro[3.4]octa-1,5-diene derivatives: Hybrid spiro compounds

Article abstract of DOI:10.1002/aoc.3303

Trialkynyl(vinyl)silanes CH₂=CH=(C=Ci=R)₃ (R=Bu, Ph, p-tolyl) were prepared and treated with 9-borabicyclo[3.3.1]nonane (9-BBN). Consecutive 1,2-hydroboration and intramolecular 1,1-carboboration reactions (each requires different reaction conditions) were studied. 1,2-Hydroboration of the Si-vinyl group takes place at ambient temperature (23°C in tetrahydrofuran), followed by intramolecular 1,1-vinylboration to give 1-silacyclopent-2-ene derivatives, bearing still two alkynyl functions at the silicon atom. Further treatment with a second equivalent of 9-BBN affords 1-alkenyl-1-(alkynyl)-1-silacyclopent-2-ene derivatives. These undergo intramolecular 1,1-vinylboration to give 4-silaspiro[3.4]octa-1,5-dienes bearing the boryl groups at 2 and 6 positions. Protodeborylation of all new compounds (intermediates and final products) using acetic acid in slight excess afforded corresponding silanes including spirosilanes. All compounds were characterized using multinuclear NMR spectroscopy (¹H, ¹¹B, ¹³C, ²⁹Si) in solution state. Solid-state structures for one of the trialkynyl(vinyl)silanes (R=p-tolyl) and one of the 1-silacyclopent-2-ene derivatives (R=Ph) were confirmed using X-ray diffraction.

Full text of DOI:10.1002/aoc.3303

Full Paper
Received: 12 October 2014
Revised: 16 December 2014
Accepted: 2 February 2015
Published online in Wiley Online Library: 23 March 2015
(wileyonlinelibrary.com) DOI 10.1002/aoc.3303
Synthesis of 4-silaspiro[3.4]octa-1,5-diene
derivatives: hybrid spiro compounds
Ezzat Khana*, Bernd Wrackmeyerb, Rhett Kempeb and Germund Glatzb
Trialkynyl(vinyl)silanes CH2¼CH–Si(CꢀC–R)3 (R= Bu, Ph, p-tolyl) were prepared and treated with 9-borabicyclo[3.3.1]nonane
(9-BBN). Consecutive 1,2-hydroboration and intramolecular 1,1-carboboration reactions (each requires different reaction
conditions) were studied. 1,2-Hydroboration of the Si–vinyl group takes place at ambient temperature (23°C in tetrahydro-
furan), followed by intramolecular 1,1-vinylboration to give 1-silacyclopent-2-ene derivatives, bearing still two alkynyl func-
tions at the silicon atom. Further treatment with a second equivalent of 9-BBN affords 1-alkenyl-1-(alkynyl)-1-silacyclopent-
2-ene derivatives. These undergo intramolecular 1,1-vinylboration to give 4-silaspiro[3.4]octa-1,5-dienes bearing the boryl
groups at 2 and 6 positions. Protodeborylation of all new compounds (intermediates and final products) using acetic acid in
slight excess afforded corresponding silanes including spirosilanes. All compounds were characterized using multinuclear
NMR spectroscopy (1H, 11B, 13C, 29Si) in solution state. Solid-state structures for one of the trialkynyl(vinyl)silanes (R = p-tolyl)
and one of the 1-silacyclopent-2-ene derivatives (R = Ph) were confirmed using X-ray diffraction. Copyright © 2015 John
Wiley & Sons, Ltd.
Keywords: alkynyl(vinyl)silanes; hydroboration; carboboration; protodeborylation; spirosilanes
starting silanes. Thus, an alkynylsilane bearing one vinyl group,
available for 1,2-hydroboration, and three alkynyl functions for
either intramolecular 1,1-carboboration or another 1,2-hydroboration
Introduction
Considering the enormous attraction of tetraorganosilanes,[1,2]
the class of spirosilanes has received scant attention, possibly as a
result of somewhat tedious synthetic strategies and limited
choice of substituent patterns. 1,1-Carboboration of dialkynyl- and
tetraalkynylsilanes has been shown to open a convenient route to
cyclic silanes, such as siloles or bisiloles,[3] although rather severe
reaction conditions (heating for prolonged periods of time at
100–120°C) are required when for example trialkylboranes (BR3;
R = Me, Et) are used. This problem can be circumvented using more
Lewis-acidic triorganoboranes such as B(C6F5)3.[4] Another elegant
way has been proposed by introducing the boryl group into the
respective molecule via 1,2-hydroboration, hoping for intramolecu-
lar 1,1-carboboration under relatively mild reaction conditions in
the next step.[5] Both processes, 1,2-hydroboration[6] and 1,1-
carboboration,[3] are well known for their efficiency and high selec-
tivity for reducing C–C multiple bonds of organosilane derivatives,
in most cases. Exploiting these consecutive reactions, various
silacycles have been reported.[3,7,8] 1,2-Hydroboration followed by
intramolecular 1,1-carboboration provides perhaps the most
convenient access to the formation of numerous spirosilanes. It
has advantage over other methods,[9] such as to tolerate various
substituents at different ring positions, allowing assembly of vari-
ous ring systems around the silicon atom and leading to silacycles
containing C–C unsaturated bonds.
was expected to lead finally to the desired spirosilanes containing a
five- and a four-membered ring. Silanes with general structural
formula (H2C¼CH)Si(CꢀC–R)3 (R = Bu, Ph, p-tolyl; 1a–c) fulfil all
the requirements for formation of the proposed hybrid
spirosilanes. NMR spectroscopy, in particular 13C NMR and 29Si
NMR, served to monitor the reactions, to detect intermediates
and to characterize the products in solution. Some precursors
were obtained as solid crystalline materials, for which crystal
structures could be determined supporting the proposed reac-
tions. Moreover, density functional theory calculations enabled a
comparison of optimized gas-phase structures with experimental
data, including NMR parameters.
Results and Discussion
Starting Materials
Trialkynyl(vinyl)silanes act as starting materials for the syntheses of
the title compounds. They can be obtained by the reaction of
alkynyl lithium reagents and trichloro(vinyl)silane (in 3:1 ratio) at
ꢁ78°C.[12] They are colourless oily (1a), waxy (1b) or crystalline
solids (1c), and can tolerate air, moisture and fairly high temperature
We have reported the spirosilanes 4-silaspiro[3.3]hepta-1,5-
dienes (A)[10] and 5-silaspiro[4.4]nona-1,6-dienes (B)[11] (Fig. 1)
containing axially chiral silicon atoms. The reactions were carried
out for a variety of substituents on ring carbons and it was con-
cluded that the nature of R (alkyl, aryl, heteroaryl) does not affect
the course of chemical reactions.[11]
*
Correspondence to: Ezzat Khan, Department of Chemistry, University of
Malakand, 18550 Chakdara, Dir (Lower), Khyber Pakhtunkhwa, Pakistan. E-mail:
ekhan@uom.edu.pk
a Department of Chemistry, University of Malakand, 18550, Chakdara, Dir (Lower),
Khyber Pakhtunkhwa, Pakistan
In continuation of this work, a hybrid of A and B could be made
accessible if appropriate functional groups are present in the
b Anorganische Chemie II, Universität Bayreuth, D-95440, Bayreuth, Germany
Appl. Organometal. Chem. 2015, 29, 384–391
Copyright © 2015 John Wiley & Sons, Ltd.

Synthesis and characterization of hybrid spirosilanes
Figure 1. Spirosilanes (R = alkyl, aryl) obtained via consecutive 1,2-
hydroboration and 1,1-carboboration reactions.
(>150°C). They were purified by fractional distillation (1a) or recrys-
tallization (1b and 1c) and were characterized using NMR spectros-
copy in solution state, together with one example (1c) in solid state
using X-ray diffraction (Experimental section; Table 1 and Fig. 2).
Although the structure solution of silane 1c suffers from some
sort of disorder, the structure can be solved without obstructions
and connectivities (except C¼C bond) can be established for atoms
with the required accuracy. Apparently, there are weak intermolec-
ular interactions between the vinyl unit and one of the alkynyl
groups of a neighbouring molecule, one of the possible reasons
for disorder. The geometry around the silicon atom is close to per-
fect tetrahedral. All C–Si–C angles are in the range 109.0–110.8°, ex-
cept C13–Si1–C22 (106.7°). All other bond angles and bond lengths
are within the expected range reported for alkynylsilanes as well as
alkynylgermanes.[13] Interestingly, density functional theory calcula-
tions show the optimized gas-phase structure of 1c with a preferred
intramolecular orientation of the –CH¼CH2 group along the vector
of one of the CꢀC bonds (Fig. 3). The optimized structure of the
Figure 2. Molecular structure of 1c (ORTEP plot ellipsoids drawn at 40%
probability level, hydrogen atoms are omitted for clarity). Selected bond
lengths (pm) and bond angles (°): C1–Si1 182.7(4), C4–C5 120.8(4), C4–Si1
180.9(4), C22–Si1 183.2(3); C2A–C1–Si1 132.0(6), C5–C4–Si1 177.6(3),
C14–C13–Si1 173.9(2), C23–C22–Si1 175.8(3), C4–Si1–C13 110.6(14), C4–Si1–
C1 110.8(18), C13–Si1–C1 109.7(2), C4–Si1–C22 110.0(14), C1–Si1–C22 109.0(15).
Table 1. Data pertinent to the crystal structure determinations of 1c
and 5b
1c
5b
Formula
C58H48B2Si2
C52H40Si2
Crystal
Colourless prism
0.77 × 0.23 × 0.11
Monoclinic
C2
Colourless prism
1.08 × 0.77 × 0.61
Orthorhombic
Pca21
Dimensions (mm)
Crystal system
Space group
Lattice parameters
a (pm)
Figure 3. Calculated optimized gas-phase geometries (B3LYP/6-311 + G(d,
p) level of theory) of 1c and the parent compound CH2¼CH–Si(CꢀCH)3.
2019.9(2)
608.2(7)
1915.1(2)
90.0
3551.7(4)
1011.9(12)
1110.9(12)
90.00
b (pm)
c (pm)
parent compound CH2¼CH–Si(CꢀCH)3 also shows this particular
structural feature. Since the calculated NMR parameters (see below)
such as chemical shifts δ (13C) and coupling constants J(29Si,13C) are
very similar for all three alkynyl groups, these interactions must be
rather weak.
α = γ (°)
β (°)
Z
Volume (Å3)
F (000)
Abs. coeff. μ (mmꢁ1
Diffractometer
91.1(10)
2
126.478(10)
4
2352.1(4)
848
3992.8(8)
1520
)
0.11
0.13
STOE IPDS II, Mo Kα, λ = 71.069 pm,
graphite monochromator
1,2-Hydroboration and 1,1-Carboboration
The presence of at least one Si–CH¼CH2 function, in addition to the
Si–CꢀC– units (1a–c), enhances the utility of these compounds.
When treated with 9-borabicyclo[3.3.1]nonane (9-BBN),[14,15] such
silanes react preferably at the Si–CH¼CH2 group via regioselective
1,2-hydroboration, even in the presence of three Si–CꢀC– units
(Scheme 1). After 1,2-hydroboration of the Si–vinyl group, the boryl
group occupies a position favourable for intramolecular 1,1-
vinylboration (intermediates in square brackets are not detected)
Measuring range (°)
2.0–25.8
4369
2.0–25.7
7072
Reflections collected
Ind. reflections (I > 2σ(I))
Data/restraint/parameters
wR2/R1 (I > 2σ(I))
Max./min. residual electron
density (×10ꢁ6 epmꢁ3
2736
3834
2736/1/280
0.046/0.077
0.29/ꢁ0.17
3834/1/487
0.079/0.116
0.25/ꢁ0.23
)
Appl. Organometal. Chem. 2015, 29, 384–391
Copyright © 2015 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

E. Khan et al.
Scheme 1. 1,2-Hydroboration of trialkynyl(vinyl)silane derivatives 1a–c at
ambient temperature. Intramolecular activation of the Si–Cꢀ bond is
indicated by the dashed line.
to afford 1-silacyclopent-2-ene derivatives 2a–c (ca 1 h reaction
time at room temperature). The silanes 2a–c as shown in Scheme 1
(see also Figs 4 and 5) possess two alkynyl functional groups which
can react further with another equivalent of 9-BBN. However, this
second 1,2-hydroboration takes place much more slowly (ca 24 h
at 23°C and less than 5% conversion can be observed) to afford in-
termediates 3a and 3b (Scheme 2). The same mixture, after heating
to 80°C in toluene for several minutes, shows considerable progress
in the second 1,2-hydroboration reaction (>80%, NMR spectros-
copy). Intermediates 3a and 3b are stable at room temperature,
and ring closure to 4 is negligible or not observed even after
four days at room temperature. This is a positive aspect of such
Scheme 2. 1,2-Hydroboration, followed by intramolecular 1,1-
carboboration, of 1-silacyclopent-2-ene derivatives 2a and 2b using 9-BBN
as hydroborating reagent.
intermediates as they can be characterized in solution state
using NMR spectroscopy (Fig. 4) and it is helpful in understand-
ing the reaction pathway (Schemes 1 and 2). The dashed line
between boron atom and alkynyl group in 3 indicates Si–Cꢀ
bond activation leading to Si–Cꢀ bond cleavage. Heating of in-
termediates 3a and 3b at 80°C for 1 to 6 h is required for intra-
molecular rearrangement into 4a and 4b. These desired hybrid
spirosilanes (Scheme 2) are formed almost quantitatively
(>90%, from NMR spectra). Clearly, 29Si NMR spectroscopy serves
as a powerful tool for monitoring the progress of the reactions
since all silanes shown in the schemes possess distinct chemical
shifts δ (29Si) (Figs 4 and 5).
Protodeborylation
The presence of a diorganoboryl group invites further chemistry.
Compounds containing this group may be converted into hydroly-
sis or oxidation products and most importantly into Suzuki-type
coupling products.[16] Compounds 2, 3 and 4 bear boryl substitu-
ents, which can be replaced simply by hydrogen by treating these
compounds with an excess of acetic acid. Since all other functions
show sufficient stability in the presence of acetic acid, the boryl
group can easily be removed (Scheme 3). The resulting bicyclic bo-
ron compound 10 is isolated following a literature procedure,[17]
and the desired boron-free pure compounds are obtained as vis-
cous oils or crystalline material (9b) (Scheme 4).
Figure 4. 59.6 MHz 29Si{1H} NMR spectra of a mixture containing 2a and 3a.
Expansions are given for both the signals showing 13C satellites, marked by
asterisks, corresponding to coupling constants 1/2J(29Si,13C), given in square
brackets.
NMR Spectroscopic Studies for Structural Elucidation
Although typical 11B chemical shifts[18] of compounds 2, 3 and 4
(Experimental section) reveal the presence of three-coordinate
boron atoms linked to three carbons, much more additional proof
for the solution-state structures is required. As already pointed
out, 29Si NMR spectra are helpful (Figs 3 and 4), in particular if the
signal-to-noise ratio enables assignment of 13C satellites corre-
sponding to coupling constants nJ(29Si,13C) (n = 1, 2) (Figs 3 and 5).
Figure 5. 59.6 MHz 29Si{1H} NMR spectra (refocused INEPT) of reaction
mixture containing 1-silacyclopent-2-ene derivatives 2b, 3b and
spirosilane 4b.
wileyonlinelibrary.com/journal/aoc
Copyright © 2015 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2015, 29, 384–391

Synthesis and characterization of hybrid spirosilanes
Figure 7. 100.5 MHz 13C{1H} NMR spectrum of 9b. Aliphatic (upper trace)
and olefinic (lower trace) expansions are given for carbons showing 29Si
coupling satellites, marked by asterisks and arrows corresponding to
1J(29Si,13C) and 2J(29Si,13C), respectively. The values of corresponding
coupling constants are given in square brackets.
Scheme 3. Protodeborylation of synthesized compounds at various stages.
boryl-substituted derivatives by typically broadened 13C NMR
signals of carbon atoms linked to boron.[19,20]
Calculations of 29Si chemical shifts[20,21] based on optimized gas-
phase geometries reflect the experimental data, showing the in-
creased 29Si magnetic shielding with increasing number of alkynyl
groups and the typical deshielding in five-membered rings,[20] in
contrast to comparable non-cyclic derivatives or four-membered
rings. The structural dependence of coupling constants nJ(29Si,13C)
is also noteworthy, and the experimental data (Figs 4, 6 and 7) are
reasonably well reproduced by the calculated values (Fig. 8).
Scheme 4. Synthesis of 7b and 8b using 5b as precursor.
Protodeborylation of 8b leads to the formation of 9b.
X-ray Diffraction Study of 5b
The molecular structure of 5b[21] is shown in Fig. 9, together with
selected bond lengths and angles. Relevant data for crystal struc-
ture determination and refinement are listed in Table 1. In a mole-
cule of 5b, all atoms of the principal plane (1-silacyclopent-2-ene)
deviate from planarity. The C2–Ph (C21–C26) plane is twisted by
an angle of 10.6° and the Ph rings attached to ꢀC– atoms (C3–C8
and C11–C16) form angles of 82.0° and 97.0°, respectively, with
the principal plane. The endocyclic C–Si–C angle is expectedly
smaller (∠C17–Si1–C20 = 94.9°) than the excocyclic angles (∠C1–
Si1–C17 = 109.8°, ∠C1–Si1–C9 = 106.8° and ∠C9–Si1–C17 = 116.8°).
The surroundings of silicon atom are distorted tetrahedral, and all
bond lengths and angles of 1-silacyclopent-2-ene ring are well
comparable with analogous structures containing the same ring
system.[7,8] Bond lengths of C18–C19 and C17¼C18 are slightly
shorter than the analogous bonds in 9-BBN-substituted
derivatives.[7,8] The elongation of these bonds in the latter case
can be traced to hyperconjugation involving the empty pz orbital
of the boron and C–C σ-bonds.[22–24] The CꢀC bond lengths
(120.8(8) pm) in 5b are identical to those in 1c.
Figure 6. Expansion of 59.6 MHz 29Si{1H} NMR spectrum of 6b, showing 13
C
satellites, marked by asterisks, corresponding to coupling constants
1/2J(29Si,13C), given in square brackets.
Conclusions
The latter information is complemented by 13C NMR spectra
showing the 29Si Satellites for relevant signals, together with
characteristic 13C chemical shifts (Fig. 6), and in the case of the
Hybrid spirosilanes, 4-silaspiro[3.4]octa-1,5-dienes, bearing boryl
groups and R substituents (R= Bu, Ph) are accessible in high yield
Appl. Organometal. Chem. 2015, 29, 384–391
Copyright © 2015 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

E. Khan et al.
Figure 8. Calculated coupling constants nJ(29Si,13C) (n = 1, 2) based on optimized gas-phase geometries (B3LYP/6-311 + G(d,p) level of theory). For
experimental data, see Figs 4, 6 and 7.
methylbenzene, 1-hexyne, glacial acetic acid and 9-BBN were used
as commercial products without further purification. Mass spectra:
FOCUS DSQ (Thermo) mass spectrometer; the m/z data refer to the
isotopes 1H, 11B, 12C, 28Si (5b only). NMR measurements in C6D6 (con-
centration ca 10–15%) with samples in 5 mm tubes at 23 1°C:
1
Varian Inova 300 and 400 MHz spectrometers for H, 11B, 13C and
29Si NMR; chemical shifts are given relative to Me4Si (δ1H (C6D5H)
= 7.15; δ13C (C6D6) = 128.0; δ29Si = 0 for Ξ(29Si) = 19.867184 MHz); exter-
nal BF3–OEt2 (δ11B=0 for Ξ(11B) = 32.083971 MHz). Chemical shifts are
given to 0.1 ppm for 13C and 29Si, and 0.4 ppm for 11B; coupling
constants are given to 0.4 Hz for J(29Si,13C). 29Si NMR spectra
were measured using the refocused INEPT pulse sequence,[25]
3
based on J(29Si,1H) (15–25 Hz) after optimizing the delay times
in the pulse sequence. The melting points (uncorrected) were de-
termined using a Büchi 510 melting point apparatus.
All quantum-chemical calculations were carried out using the
Gaussian 09 program package.[26] Optimized geometries at the
B3LYP/6-311 + G(d.p) level of theory[27] were found to be minima
by the absence of imaginary frequencies. NMR parameters were
calculated[28,29] at the same level of theory. Calculated nuclear mag-
Figure 9. Molecular structure of 5b (ORTEP plot, ellipsoids drawn at 40%
probability level, hydrogen atoms are omitted for clarity). Selected bond
netic shielding constants σ11
B
were converted by δ11B
lengths (pm) and bond angles (°): C1–C2 120.8(8), C9–C10 121.2(8), C1–Si1
182.7(7), C17–C18 132.8(8), C17–Si1 184.2(7), C18–C19 150.8(8), C19–C20
155.0(8), C20–Si1 185.5(6); C2–C1–Si1 173.4(6), C1–C2–C3 176.5(7),
C10–C9–Si1 176.3(6), C18–C17–Si1 107.0(5), C17–C18–C19 120.1(6), C18–
C19–C20 109.4(5), C19–C20–Si1 102.7(4), C9–Si1–C1 106.8(3), C1–Si1–C17
109.8(3), C17–Si1–C20 94.9(3).
(calcd) = σ(11B)ꢁ σ(11B, B2H6), with σ(11B, B2H6) = +84.1 (δ11B
(B2H6) = 18 and δ11B (BF3–OEt2) = 0), and calculated σ(29Si) were
converted to chemical shifts δ29Si by δ29Si (calcd)= σ(29Si,
TMS)ꢁ σ(29Si), with σ(29Si, TMS)= +340.1 and δ29Si (TMS) = 0.
Syntheses of Trialkynyl(vinyl)silanes 1a and 1b
by combining consecutive intermolecular 1,2-hydroboration and
intramolecular 1,1-carboboration reactions. So far the combination
of these processes appears to open the only access to such
spirosilanes. Protodeboylation of precursors and final products
was successfully carried out under ambient reaction conditions.
All precursors and spirosilanes are sufficiently stable in acetic acid
solution and no side reactions/products were observed. Solution-
state NMR data served for structural assignments of precursors, in-
termediates and final products, confirmed by calculated optimized
gas-phase structures and calculated NMR parameters.
A freshly prepared suspension of hexyn-1-yllithium (25.0mmol) in
hexane (60.0 ml) was cooled to ꢁ78°C and trichloro(vinyl)silane
(8.3mmol, 1.3ml) was slowly added. The reaction mixture was
warmed to room temperature and stirring was continued for 12 h
(overnight). Insoluble materials were separated and all readily
volatile materials were removed under reduced pressure. The
colourless oily residue was identified as a mixture of 1a and
Si(Cl)(CH¼CH2)(CꢀC–Bu)2. The silane Si(CH¼CH2)(CꢀC–Bu)2Cl
(δ29Si= ꢁ46.3; b.p. = 150–155°C/6.5 × 10ꢁ1 mbar) was separated by
fractional distillation and a pure sample of 1a was obtained and
characterized using multinuclear NMR spectroscopy (1H, 13C and
29Si). The same synthetic pathway was followed for the synthesis
of 1b, except purification of the reaction mixture. The residual solid
(LiCl including 1b) was washed with toluene, all volatiles were re-
moved in vacuo and 1b (ca 85%) was obtained as a waxy solid.
Experimental
General
All manipulations were performed observing precautions to exclude The solid was washed two to three times with pentane and all
traces of air and moisture in Schlenk-type glassware. Carefully dried lighter fractions and impurities were isolated, to give pure 1b
solvents and oven-dried glassware were used throughout. BuLi in (98%, NMR spectra). Preparation and experimental work up for 1c
hexane (1.6 M), trichloro(vinyl)silane, ethynylbenzene, 1-ethynyl-4- were exactly the same as for 1a and 1b. The silane
wileyonlinelibrary.com/journal/aoc
Copyright © 2015 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2015, 29, 384–391

Synthesis and characterization of hybrid spirosilanes
Si(Cl)(CH¼CH2)(CꢀC–4-Me–C6H4)2 was washed with hexane and
the remaining solid residue was dissolved in THF. Needle-like
colourless crystals appeared after 3–4 days. A single crystal of suit-
able dimensions was selected and studied using X-ray diffraction.
31.5-br, 32.2-br, 33.7, 33.8, 34.5, 34.6 (2 × 9-BBN), 85.0 [85.7 Hz] (Si–
Cꢀ), 110.0 [15.6 Hz] (Cꢀ), 146.1 (br, B–C¼), 158.5 (¼CH). 29Si NMR:
δ =ꢁ17.2. 11B NMR: δ =84.8.
3b. 1H NMR (300 MHz): δ =1.2 (m, 2H, C5H2), 2.9 (m, 2H, C4H2), 1.3–
2.1 (m, 14H, 9-BBN), 6.8–7.5 (m, 15H, Ph), 8.0 (s, 1H, 3J(29Si,1H) = 17.8 Hz,
¼CH). 13C NMR: δ [J(29Si,13C)] = 147.9 [68.3 Hz] (C2), 173.7-br (C3), 33.6
(C4), 12.5 [58.8 Hz] (C5), 23.6, 23.8, 31.9-br, 32.3-br, 34.3, 34.5, 34.7,
34.8 (2 × 9-BBN), 94.5 [85.6 Hz] (Si–Cꢀ), 108.7 [15.9 Hz] (ꢀC), 123.8,
125.7, 126.4, 128.1, 128.1, 128.4, 128.6, 129.3, 129.6, 132.1, 140.7,
142.8 (3 × Ph), 148.2-br (B–C¼), 154.6 (¼CH). 29Si NMR: δ =ꢁ14.4.
11B NMR: δ = 87.3.
1
1a. Yield 86%. H NMR (400 MHz, C6D6): δ = 0.7, 1.2, 1.9 (t, m, t,
27H, Bu), 5.9 (m, 1H, ¼CH), 6.0 (m, 1H, ¼CH), 6.3 (m, 1H, HC¼). 13
C
NMR (100.5 MHz): δ [J(29Si,13C)] = 13.6, 19.9, 22.1, 30.5 (Bu), 79.0
[116.6Hz] (Si–Cꢀ), 109.7 [23.0 Hz] (ꢀC), 133.9 [87.7 Hz] (Si–C¼),
135.2 (¼C). 29Si NMR (59.6MHz): δ = ꢁ73.9.
1b. Yield 85%. 1H NMR (300 MHz, C6D6): δ = 6.1 (dd, 1H, J(1H,1H)
= 13.5, 4.2 Hz, ¼CH2), 6.5 (dd, 1H, J(1H,1H) = 20.1, 13.5Hz, HC¼), 6.6
(dd, 1H, J(1H,1H) = 20.1, 4.2 Hz, ¼CH2), 6.8–6.9, 7.3–7.4 (m, m, 15H,
Ph). 13C NMR (100.5MHz): δ [J(29Si,13C)] =87.2 [116.4Hz] (Si–Cꢀ),
108.2 [23.0 Hz] (ꢀC), 132.0 [89.6Hz] (Si–C¼), 137.1 (¼C), 122.5,
132.6, 128.4, 129.4 (Ph). 29Si NMR (59.6MHz): δ = ꢁ71.2.
4a. 1H NMR (300 MHz): δ =0.9, 0.9, 1.2–1.6, 1.8–2.1, 2.5, 2.8 (t, t, m, m,
m, m, protons not assigned, Bu, 9-BBN, C4H2, C5H2), 6.0 (t, 1H, 3J(1H,1H)
=6.8Hz, ¼CH). 13C NMR: δ [J(29Si,13C)] = 168.0 [49.3] (C1), 177.6-br (C2),
148.8 [50.5] (C3), 147.9 [55.9] (C5), 170.7-br (C6), 33.5 (C7), 9.9 [46.4] (C8),
127.5 (¼CH), 14.3, 14.4, 14.4, 23.0, 23.2, 23.5, 32.6, 32.9, 33.2, 33.9, 34.1,
34.6 (3 × Bu), 23.6, 23.6, 31.4-br, 32.5-br, 33.8, 33.4, 33.4 (2 × 9-BBN). 29Si
NMR: δ =22.7. 11B NMR: δ = 84.7.
1c. Yield 85%; m. p. 108–110°C. 1H NMR (400 MHz, CDCl3): δ = 6.5,
6.6, 6.7 (m, m, m, 3H, Si–C2H3), 2.6 (s, Me), 7.4, 7.7 (m, m, 12H, 4-
Me–C6H4). 13C NMR (100.5MHz): δ [J(29Si,13C)] = 85.7 [116.4Hz]
(Si–Cꢀ), 107.5 [22.9Hz] (ꢀC)], 21.5 (Me), 119.1, 132.2, 129.9,
139.5 (4-Me–C6H4). 29Si NMR (59.6MHz): δ = ꢁ71.8.
4b. 1H NMR (400 MHz): δ =1.3 (m, 2H, C8H2), 2.9 (m, 2H, C7H2), 1.4,
1.6–2.0 (m, m, 28H, 9-BBN), 6.9–7.2, 7.4 (m, m, 16H, ¼CH, Ph). 13C NMR:
δ [J(29Si,13C)] = 163.2 [51.1] (C1), 180.1-br (C2), 150.9 [49.6] (C3), 147.3
[57.5] (C5), 177.5-br (C6), 33.8 (C7), 9.5 [48.2] (C8), 132.4 (¼CH), 23.6,
23.7, 32.3-br, 32.9-br, 34.2, 34.3, 34.6, 34.8 (2 × 9-BBN), 142.5 [6.5],
140.6 [6.8], 139.9, 128.9, 128.6, 128.5, 128.4, 128.2, 127.1, 126.9, 126.7
(3 × Ph). 29Si NMR: δ = 22.6. 11B NMR: δ = 88.1.
Syntheses of 1,1-(Dialkyn-1-yl)-1-silacyclopent-2-ene
Derivatives 2a–c, 3a,b and 4a,b
A Schlenk tube was charged with a solution of 1a (1.6 g, 5.4 mmol)
in THF (10ml) and one equivalent of 9-BBN (0.58 g, 5.4mmol). The
reaction mixture was stirred at room temperature for 30–40min,
and all volatile materials were removed under reduced pressure.
The reaction afforded pure 2a (>90%, NMR spectroscopy) which
was used for further transformations. Important NMR data were col-
lected for 2a and it was dissolved in 5 ml of toluene and one further
equivalent of 9-BBN (0.58 g, 5.4mmol) was added. The reaction
mixture was heated to 80°C for ca 4 h to give 3a, followed by intra-
molecular 1,1-carboboration to afford 4a. The procedure for the
preparation of silanes 3b and 4b was exactly the same.
Protodeborylation of 1-Silacyclopent-2-ene Derivatives 2, 3
and spirosilanes 4a,b
A solution of 2a (1.26 g, 3.0 mmol) in pentane (10 ml) was mixed with
an excess of acetic acid (2 ml) at 23°C. The reaction mixture was
stirred for 40–60 min. All readily volatile materials were removed
under reduced pressure. The oily residue left was dissolved in pen-
tane and the solution was kept at ꢁ35°C. Most of the fairly insoluble
boron–oxygen compound 10 settled and was separated. The solvent
and other readily volatile material were evaporated. The mixture con-
taining 5a and trace amount of 10 was heated to 80°C under reduced
pressure (10ꢁ2 torr) for 1 h. Pure 5a was obtained as a colourless
viscous oil. The protodeborylation reactions of silanes 2b, 3a,b and
4a,b with acetic acid were carried out under identical reaction
conditions.
The silane 5b was taken up into a Schlenk tube and was
dissolved in 2–3 ml of diethylether. After 24 h, colourless crystals
of 5b suitable for X-ray single-crystal analysis were obtained at
273 K, and a single crystal of appropriate dimensions was selected
at room temperature for X-ray diffraction.
2a. 1H NMR (300 MHz): δ = 0.7, 1.0, 1.2–1.4, 2.0, 2.6 (t, t, m, m, m,
27H, Bu), 1.2 (m, 2H, C5H2), 2.5 (m, 2H, C4H2), 1.3, 1.8–2.0 (m, 14H,
BBN). 13C NMR: δ [J(29Si,13C)] = 146.0 [74.6Hz] (C2), 169.3-br (C3),
34.6 (C4), 11.9 [64.5 Hz] (C5), 13.7, 20.1, 22.2, 30.8 (ꢀC–Bu), 14.5,
23.8, 34.5, 34.1 (C2–Bu), 23.5, 32.2-br, 33.8 (9-BBN), 81.5 [98.4 Hz]
(Si–Cꢀ), 109.8 [19.9Hz] (ꢀC). 29Si NMR: δ = ꢁ32.2. 11B NMR: δ = 85.1.
2b. 1H NMR (300 MHz): δ = 1.3, 1.6–1.8 (m, m, 14H, 9-BBN), 1.5 (dd,
2H, C5H2), 2.9 (dd, 2H, C4H2), 6.8–6.9, 7.0–7.2, 7.3, 7.6 (m, m, m, m,
15H, Ph). 13C NMR: δ [J(29Si,13C)] =144.5 [77.8Hz] (C2), 175.50-br
(C3), 34.9 (C4), 12.3 [64.8Hz] (C5), 34.5, 32.4-br, 23.5 (9-BBN), 90.0
[98.7Hz] (Si-Cꢀ), 108.5 [19.3 Hz] (ꢀC), 142.0, 128.9, 128.5, 126.9
(C2-Ph), 123.0, 132.5, 128.4, 129.1 (2 × ꢀC-Ph). 29Si NMR: δ = ꢁ30.3.
11B NMR: δ = 85.1.
5a. Yield 50%. 1H NMR (300 MHz): δ = 0.7, 0.9, 1.2–1.3, 2.0, 2.4 (t, m,
m, t, m, 27H, Bu), 1.1 (m, 2H, C5H2), 2.3 (m, 2H, C4H2), 6.3 (m, 1H, C3H).
13C NMR: δ [J(29Si,13C)] = 142.2 [75.1 Hz] (C2), 148.3 [15.5Hz] (C3),
32.3 (C4), 11.2 [63.7Hz] (C5), 13.6, 19.9, 22.2, 30.7 (2× ꢀC–Bu), 14.3,
23.1, 30.2, 32.5 (C2–Bu), 81.0 [100.0Hz] (Si–Cꢀ), 109.8 [19.2 Hz]
(ꢀC). 29Si NMR: δ = ꢁ34.5.
2c. 1H NMR (400 MHz): δ = 1.1, 1.5–1.9 (m, m, 14H, 9-BBN), 0.8 (m, 2H,
C5H2), 2.6 (m, 2H, C4H2), 1.6 (s, Me), 1.8 (s, Me), 6.4, 6.7, 7.0, 7.3 (m, m, m,
m, 12H, 4-Me–C6H4). 13C NMR: δ [J(29Si,13C)] = 144.9 [75.9 Hz] (C2),
174.2-br (C3), 34.9 (C4), 12.5 [64.9 Hz] (C5), 23.6, 32.3-br, 34.6 (9-BBN),
89.6 [99.6 Hz] (Si–Cꢀ), 108.7 [19.1 Hz] (ꢀC), 21.3 (Me), 120.2, 132.4,
129.2, 139.1 (2 × ꢀC–(4-Me–C6H4)), 21.1 (Me), 136.2, 132.6, 129.0,
140.3 (C2–(4-Me–C6H4)). 29Si NMR: δ =ꢁ30.5. 11B NMR: δ = 84.3.
3a. 1H NMR (300 MHz): δ = 0.8, 0.9, 1.0, 1.2–1.5, 2.4–2.9 (t, t, t, m, m,
5b. Yield 65%; m.p. 84–86°C. 1H NMR (300 MHz): δ = 1.3 (t, 2H, 3J
(1H,1H) = 6.8 Hz, C5H2), 2.4 (m, 2H, C4H2), 7.1 (t, 1H, 3J(1H,1H)
= 7.3 Hz, C2H), 6.9, 7.2, 7.4, 7.9 (m, m, m, m, 15H, Ph). 13C NMR: δ [J
(29Si,13C)] = 139.9 [76.8Hz] (C2), 150.0 [14.8 Hz] (C3), 31.0 (C4), 10.8
[58.9 Hz] (C5), 89.6 [100.2 Hz] (Si–Cꢀ), 108.5 [19.5Hz] (ꢀC), 122.9,
132.4, 128.4, 129.1 (2 × ꢀC–Ph), 138.7 [5.2 Hz], 129.0, 127.6,
127.3 (C2–Ph). 29Si NMR: δ = ꢁ32.5. GC-MS: tR = 26.98 min; m/z
(%) = 360.1 (42) [M+], 282.1 (6) [M+ ꢁ C6H6], 258.0 (100)
[M+ ꢁ C8H6], 229.0 (22) [M+ ꢁ C10H11], 180.0 (52) [M+ ꢁ C14H12],
3
Bu, C4H2, C5H2), 1.4, 1.7–2.1 (m, m, 28H, 9-BBN), 7.0 (t, 1H, J(1H,1H)
=7.2Hz, ¼CH). 13C NMR: δ [J(29Si,13C)] = 148.7 [66.7 Hz] (C2), 168.0
(br, C3), 34.1 (C4), 12.5 [58.6 Hz] (C5), 13.7, 20.2, 22.3, 30.8 (ꢀC–Bu),
14.3, 14.4, 23.1, 23.8, 32.1, 33.7, 33.3, 35.0 (C2–Bu, ¼C–Bu), 23.5, 23.8,
Appl. Organometal. Chem. 2015, 29, 384–391
Copyright © 2015 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc

E. Khan et al.
129.0 (72) [M+ ꢁ C18H15].
Acknowledgements
1
6a. Yield 59%. H NMR (300 MHz): δ = 0.8, 0.9, 0.9, 1.2–1.4, 2.1,
Financial support from Higher Education Commission (HEC)
Pakistan under National Research Program for Universities (NRPU)
no. 20-1488/R&D/09-5432 is gratefully acknowledged. EK and BW
are also grateful to DAAD and Deutsche Forschungsgemeinschaft
for support.
2.2–2.4 (t, t, t, m, t, m, 31H, Bu, C4H2, C5H2), 5.7 (d, 1H, J(1H,1H)
3
= 13.8 Hz, ¼C(Si)H), 6.3 (m, 1H, C3H), 6.4 (dt, 1H, 3J(1H,1H)= 7.5,
13.8 Hz, H(Bu)C¼). 13C NMR: δ [J(29Si,13C)] =143.4 [68.9Hz] (C2),
147.2 [13.6 Hz] (C3), 32.2 (C4), 11.2 [58.7 Hz] (C5), 13.8, 20.1, 22.2,
30.6 (ꢀC–Bu), 14.3, 14.3, 22.9, 23.2, 31.0, 32.4, 32.8 [5.4 Hz], 33.7
(2× Bu), 83.0 [88.9 Hz] (Si–Cꢀ), 109.6 [17.1 Hz] (ꢀC), 125.2 [73.0 Hz]
(Si–C¼), 151.9 (¼C–Bu). 29Si NMR: δ = ꢁ21.6.
6b. Yield 55%. 1H NMR (300MHz): δ = 0.9 (m, 2H, C5H2), 2.2 (m, 2H,
C4H2), 5.8 (d, 1H, 3J(1H,1H)= 14.8 Hz, ¼CH), 6.5–7.2, 7.4, 7.6 (m, m, m,
17H, ¼CH, C3H, Ph). 13C NMR: δ [J(29Si,13C)] = 141.9 [70.6 Hz] (C2),
148.9 [13.4 Hz] (C3), 31.1 (C4), 10.1 [60.2Hz] (C5), 92.1 [88.5Hz]
(Si–Cꢀ), 108.4 [16.7Hz] (ꢀC), 139.6, 139.4 [5.6 Hz], 132.3, 129.3,
128.9, 128.7, 128.5, 128.4, 128.3, 128.2, 127.3, 123.3 (3 × Ph),
126.4 [72.9 Hz] (Si–C¼), 149.7 (¼C–Bu). 29Si NMR: δ = ꢁ18.5.
9b. Yield 56%. 1H NMR (300 MHz): δ = 0.9, 1.2 (m, m, 2H, C8H2),
2.6 (m, 2H, C7H2), 6.9–7.2, 7.4, 7.5 (m, m, m, 17H, Ph, C6H, ¼CH),
References
[1] a) Z. Rappoport, Y. Apeloig (Eds), The Chemistry of Organic Silicon Com-
pounds, Vol. 3, Wiley, Chichester, 2001; b) B. Marciniec, J. Chojnowski
(Eds), Progress in Organosilicon Chemistry, Gordon and Breach, Basel,
1995.
[2] a) N. Auner, J. Weis (Eds), Organosilicon Chemistry, Vol. VI, Wiley-
VCH, Weinheim, 2005; b) U. Schubert (Ed), Silicon Chemistry,
Springer, Belin, 1999; c) M. A. Brook, Silicon in Organic,
Organometallic and Polymer Chemistry, Wiley-VCH, Weinheim,
2000.
[3] a) B. Wrackmeyer, Coord. Chem. Rev. 1995, 145, 125–156; b)
B. Wrackmeyer, Heteroat. Chem. 2006, 17, 188–206.
[4] a) G. Dierker, J. Ugolotti, G. Kehr, R. Fröhlich, G. Erker, Adv. Synth. Catal.
2009, 351, 1080–1088; b) J. Ugolotti, G. Kehr, R. Fröhlich, G. Erker, Chem.
Commun. 2010, 46, 3016–3018.
[5] a) B. Wrackmeyer, E. Khan, R. Kempe, Appl. Organometal. Chem. 2007,
21, 39–45; b) B. Wrackmeyer, E. Khan, S. Bayer, K. Shahid, Z.
Naturforsch. 2007, 62b, 1174–1182; c) B. Wrackmeyer, H. E. Maisel,
E. Molla, A. Mottalib, A. Badshah, M. H. Bhatti, S. Ali, Appl.
Organometal. Chem. 2003, 17, 465–472; d) E. Khan, B. Wrackmeyer,
Cent. Eur. J. Chem. 2011, 9, 126–132; e) E. Khan, B. Wrackmeyer, Turk.
J. Chem. 2010, 34, 793–803; f) E. Khan, S. Bayer, B. Wrackmeyer, Z.
Naturforsch. B 2009, 64, 47–57.
[6] For studies wherein hydroboration reactions have been addressed, see
for example: a) J. A. Soderquist, J. C. Colberg, L. DelValle, J. Am. Chem.
Soc. 1989, 111, 4873–4878; b) K. Uchida, K. Utimoto, H. Nozaki, J. Org.
Chem. 1976, 41, 2941–2942; c) K. Uchida, K. Utimoto, H. Nozaki,
Tetrahedron 1977, 33, 2987–2992; d) G. Zweifel, S. J. Backlund, J. Am.
Chem. Soc. 1977, 99, 3184–3185; e) M. Hoshi, Y. Masuda, A. Arase,
Bull. Chem. Soc. Jpn. 1993, 66, 914–919; f) S. Rajogopalan, G. Zweifel,
Synthesis 1984, 113–115; g) J. A. Miller, G. Zweifel, Synthesis 1981,
288–289; h) J. A. Miller, G. Zweifel, J. Am. Chem. Soc. 1981, 103, 6217–
6219; i) J. A. Soderquist, G. Leon, Tetrahedron Lett. 1998, 39, 3989–
3990; j) D. A. Singleton, J. P. Martinez, Tetrahedron Lett. 1991, 32,
7365–7368; k) B. Wrackmeyer, A. Badshah, E. Molla, A. Mottalib,
J. Organometal. Chem. 1999, 584, 98–102; l) B. Wrackmeyer, K. Shahid,
S. Ali, Appl. Organometal. Chem. 2005, 19, 377–382; m)
B. Wrackmeyer, W. Milius, M. H. Bhatti, S. Ali, J. Organometal. Chem.
2003, 669, 72–78; n) B. Wrackmeyer, E. Khan, R. Kempe, Z.
3
7.8 (s, 1H, J(29Si,1H)= 20.1Hz, C2H). 13C NMR: δ [J(29Si,13C)] = 141.6
[59.9] (C1), 153.0 [4.7] (C2), 157.9 [53.4] (C3), 145.9 [51.8] (C5), 152.0
[12.3] (C6), 30.8 (C7), 7.3 [50.3] (C8), 130.8 (¼CH), 139.9, 139.3,
137.3, 129.0, 128.9, 128.9, 128.3, 127.5, 127.3, 127.2, 126.8, 126.7
(3× Ph). 29Si NMR: δ = 19.7.
Hydroboration of 5b to Afford 7b and 8b Followed by
Protodeborylation
Silane 5b (0.90 g, 2.50 mM) was dissolved in toluene (5ml) and an
equimolar amount of 9-BBN (0.305g, 2.50 mM) was added. The
mixture was heated to 80–100°C for 30 min. The progress of the
reaction was monitored using 29Si NMR spectroscopy, showing
the formation of 7b, and heating was continued for further 1–2 h.
During this time intramolecular 1,1-carboboration took place to
give 8b. This product was subjected to protodeborylation under
the aforementioned conditions and 9b was obtained (see above).
7b. 1H NMR (400MHz): δ = 1.2, 1.4 (m, m, 2H, C5H2), 2.5, 2.6 (m, m,
2H, C4H2), 1.2, 1.7–2.0 (m, 14H, 9-BBN), 6.8, 7.0, 7.1, 7.3, 7.5 (m, m, m,
m, m, 15H, Ph), 8.1 (s, 1H, J(29Si,1H) = 17.8 Hz, ¼CH). 13C NMR: δ
3
[J(29Si,13C)] = 142.8 [69.5 Hz] (C2), 148.1 [13.1 Hz] (C3), 31.4 (C4), 12.4
[57.7Hz] (C5), 23.6, 32.9-br, 34.3, 35.0 (9-BBN), 93.4 [86.8 Hz]
(Si–Cꢀ), 108.4 [16.1 Hz] (Cꢀ), 123.7, 126.9, 127.5, 128.0, 128.3,
128.6, 128.6, 128.6, 129.7, 132.2, 139.5, 140.5 (3 × Ph), 148.0-br
(B–C¼), 155.3 (¼C). 29Si NMR: δ = ꢁ17.9. 11B NMR: δ = 84.8.
Naturforsch.
B 2007, 62, 75–81; o) B. Wrackmeyer, E. Khan,
W. Milius, Z. Naturforsch. B 2008, 63, 1267–1275.
[7] a) B. Wrackmeyer, O. L. Tok, R. Kempe, Inorg. Chim. Acta 2005, 358,
4183–4190; b) B. Wrackmeyer, O. L. Tok, W. Milius, A. Khan,
A. Badshah, Appl. Organometal. Chem. 2006, 20, 99–105.
1
8b. Yield 89%. H NMR (300 MHz): δ = 1.4, 1.7–2.2 (m, m, 14H,
[8] a) E. Khan, R. Kempe, B. Wrackmeyer, Appl. Organometal. Chem. 2009,
23, 124–131; b) E. Khan, O. L. Tok, B. Wrackmeyer, Appl. Organometal.
Chem. 2014, 28, 280–285; c) E. Khan, B. Wrackmeyer, Cent. Eur. J.
Chem. 2012, 10, 1633–1639.
BBN), 1.2 (m, 2H, CH2), 2.6 (m, 2H, CH2), 6.9–7.2, 7.4, 7.6 (m, m,
m, arylic protons, ¼CH). 13C NMR: δ [J(29Si,13C)] =157.9 [53.4]
(C1), 153.0-br (C2), 145.9 [51.9] (C3), 141.6 [60.4] (C5), 152.0
[13.3]-br (C6), 30.9 (C7), 7.4 [49.9] (C8), 139.8, 139.3 [5.7], 137.3,
130.8, 129.0, 129.0, 128.9, 128.6, 128.3, 127.5, 127.3, 127.2, 126.7
(3× Ph and ¼CH). 29Si NMR: δ = 16.8. 11B NMR: δ = 85.7.
[9] a) R. West, J. Am. Chem. Soc. 1954, 76, 6012–6014; b) I. S. Toulokhonova,
D. R. Friedrichsen, N. J. Hill, T. Müller, R. West, Angew. Chem. Int. Ed.
2006, 45, 2578–2581; c Angew. Chem. 2006, 118, 2640–2643; d)
W. J. Richter, Synthesis 1982, 1102–1102; e) R. G. Salomon, J. Org.
Chem. 1974, 39, 3602–3602; f) V. Dejean, H. Gornitzka, G. Oba,
M. Koenig, G. Manuel, Organometallics 2000, 19, 711–713; g)
K. Tamao, K. Nakamura, H. Ishii, S. Yamaguchi, M. Shiro, J. Am. Chem.
Soc. 1996, 118, 12469–12470; h) D. Terunuma, S. Hatta, T. Araki,
T. Ueki, T. Okazaki, Y. Suzuki, Bull. Chem. Soc. Jpn. 1977, 50, 1545–
1548; i) Y. T. Park, S. Q. Zhou, G. Manuel, W. P. Weber, Macromolecules
1991, 24, 3221–3226; j) D. Yan, J. Mohsseni-Ala, N. Auner, M. Bolte,
J. W. Bats, Chem. Eur. J. 2007, 13, 7204–7214; k) Y. Kuninobu,
K. Yamauchi, N. Tamura, T. Seiki, K. Takai, Angew. Chem. Int. Ed. 2013,
52, 1520–1522.
X-ray Structure Determination
Details pertinent to the crystal structure determinations are listed
in Table 1. Crystals of suitable dimensions were selected (in
perfluorinated oil[30] at room temperature), and the data collec-
tions were carried out at 133(2) K (1c, 2b) using a STOE IPDS
II system equipped with an Oxford Cryostream low-temperature
unit. Structure solutions and refinements were accomplished
using SIR97,[31] SHELXL-97[32] and WinGX.[33]
[10] B. Wrackmeyer, E. Khan, R. Kempe, Appl. Organometal. Chem. 2008, 22,
383–388.
wileyonlinelibrary.com/journal/aoc
Copyright © 2015 John Wiley & Sons, Ltd.
Appl. Organometal. Chem. 2015, 29, 384–391

Synthesis and characterization of hybrid spirosilanes
[11] a) E. Khan, B. Wrackmeyer, R. Kempe, Eur. J. Inorg. Chem. 2008,
5367–5372; b) E. Khan, B. Wrackmeyer, C. Döring, R. Kempe, Eur. J.
Inorg. Chem. 2014, 3411–3419.
[24] B. Wrackmeyer, O. L. Tok, Z. Naturforsch. B 2005, 60, 259–264.
[25] a) G. A. Morris, R. Freeman, J. Am. Chem. Soc. 1979, 101, 760–762; b)
G. A. Morris, J. Am. Chem. Soc. 1980, 102, 428–429; c) G. A. Morris,
J. Magn. Reson. 1980, 41, 185–188; d) D. P. Burum, R. R. Ernst, J. Magn.
Reson. 1980, 39, 163–168.
[12] a) W. E. Davidsohn, M. C. Henry, Chem. Rev. 1967, 67, 73–106; b)
L. Brandsma, Preparative Acetylenic Chemistry, 2nd edn, Elsevier,
Amsterdam, 1988; c) L. Brandsma, Synthesis of Acetylenes, Allenes, and
Cumulenes: Methods and Techniques, Elsevier, Amsterdam, 2004; d)
B. Wrackmeyer, E. Khan, A. Badshah, E. Molla, P. Thoma, O. L. Tok,
W. Milius, R. Kempe, J. Senker, Z. Naturforsch. 2010, 65b, 119–126; e)
B. Wrackmeyer, E. Khan, S. Bayer, O. L. Tok, E. V. Klimkina, W. Milius,
R. Kempe, Z. Naturforsch. 2010, 65b, 725–744.
[13] a) W. Uhl, J. Bohnemann, M. Layh, E.-U. Würthwein, Chem. Eur. J. 2014,
20, 8771–8781; b) W. Uhl, S. Pelties, M. Rohling, J. Tannert, Eur. J. Inorg.
Chem. 2014, 2809–2818; c) W. Uhl, M. Rohling, J. Kösters, New J. Chem.
2010, 34, 1630–1636; d) W. Uhl, J. Tannert, M. Layh, A. Hepp, S. Grimme,
T. Risthaus, Organometallics 2013, 32, 6770–6779; e) W. Uhl, M. Rohling,
E.-U. Würthwein, N. Ghavtadze, K. Bergander, Organometallics 2010, 29,
5236–5240; f) W. Uhl, A. Hepp, H. Westenberg, S. Zemke,
E.-U. Würthwein, J. Hellmann, Organometallics 2010, 29, 1406–1412;
g) W. Uhl, J. Bohnemann, B. Kappelt, A. Hepp, M. Layh, Dalton Trans.
2014, 43, 14386–14398.
[26] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb,
J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson,
H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino,
G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda,
J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai,
T. Vreven, J. A. Montgomery Jr., J. E. Peralta, F. Ogliaro, M. Bearpark,
J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith,
R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant,
S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene,
J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts,
R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli,
J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski,
G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels,
O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian
09 (revision A.02), Gaussian Inc, Wallingford, CT, 2010.
[27] a) A. D. Becke, J. Chem. Phys. 1993, 98, 5648–5652; b) C. Lee, W. Yang,
R. G. Parr, Phys. Rev. B 1988, 41, 785–789; c) P. J. Stevens, F. J. Devlin,
C. F. Chablowski, M. J. Frisch, J. Phys. Chem. 1994, 98, 11623–11627;
d) D. McLean, D. G. S. Chandler, J. Chem. Phys. 1980, 72, 5639–5648;
e) R. Krishnan, J. S. Blinkley, R. Seeger, J. A. Pople, J. Chem. Phys. 1980,
72, 650–654.
[14] a) H. C. Brown, A. W. Moerikofer, J. Am. Chem. Soc. 1963, 85, 2063–2065;
b) C. A. Brown, R. A. Coleman, J. Org. Chem. 1979, 44, 2328–2329.
[15] a)A. Suzuki, in Modern Arene Chemistry (Ed.: D. Astruc), Wiley-VCH,
Weinheim, 2002, pp. 53–106; b) N. Miyaura, A. Suzuki, Chem. Rev.
1995, 95, 2457–2483.
[16] B. Wrackmeyer, E. Khan, R. Kempe, Z. Anorg. Allg. Chem. 2007, 633,
453–457.
[28] K. Wollinski, J. F. Hinton, P. J. Pulay, J. Am. Chem. Soc. 1990, 112,
8251–8260.
[17] B. Wrackmeyer, E. Khan, R. Kempe, Z. Naturforsch. B 2008, 63, 275–279.
[18] H. Nöth, B. Wrackmeyer, in NMR: Basic Principles and Progress, vol. 14
(Eds: P. Diehl, E. Fluck, R. Kosfeld), Springer, Berlin, 1978.
[19] B. Wrackmeyer, Prog. Nucl. Magn. Reson. Spectrosc. 1979, 12, 227–259.
[20] B. Wrackmeyer, Annu. Rep. NMR Spectrosc. 2006, 57, 1–49.
[21] CCDC-1015361 (1c) and CCDC-1015362 (2b) data contain CIF files of
the molecules, which can be obtained free of charge from the Cam-
bridge Crystallographic Data Centre, via www.ccdc.cam.ac.uk/
data_request/cif.
[29] a) T. Helgaker, M. Jaszunski, M. Pecul, Progr. NMR Spectrosc. 2008, 53,
249–268; b) R. H. Contreras, V. Barone, J. C. Facelli, J. E. Peralta, Annu.
Rep. NMR Spectrosc. 2003, 51, 167–260; c) R. H. Contreras,
J. R. Cheeseman, M. J. Frisch, G. E. Scuseria, Chem. Phys. Lett. 2003,
375, 452–458.
[30] T. Kottke, D. Stalke, J. Appl. Crystallogr. 1993, 26, 615–619.
[31] A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C. Giacovazzo,
A. Guagliardi, A. G. G. Moliterni, G. Polidori, R. Spagna, J. Appl.
Crystallogr. 1999, 32, 115–119.
[22] a) R. Boese, D. Bläser, N. Niederprüm, M. Nüsse, W. A. Brett,
P. R. Schleyer, M. Bühl, N. J. R. E. Hommes, Angew. Chem. 1992, 104,
356–358; b) R. Boese, D. Bläser, N. Niederprüm, M. Nüsse, W. A. Brett,
P. R. Schleyer, M. Bühl, N. J. R. E. Hommes, Angew. Chem. Int. Ed.
1992, 31, 314–316.
[32] G. M. Sheldrick, SHELX-97, Program for Crystal Structure Analysis (release
97-2), Institut für Anorganische Chemie der Universität Göttingen,
Germany, 1998.
[33] L. J. Farrugia, J. Appl. Crystallogr. 1999, 32, 837–838.
[23] I. V. Alabugin, T. A. Zeidan, J. Am. Chem. Soc. 2002, 124, 3175–3185.
Appl. Organometal. Chem. 2015, 29, 384–391
Copyright © 2015 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/aoc