Incorporation of group 14 elements into siloxane-bridged paracyclophanes cycto-[p,p′-Me2SiC6H4EMe 2C6H4SiMe2O]2 (E = C, Si, Ge, Sn)

Article abstract of DOI:10.1021/om050265s

The bis(arylene silanes) p,p′-HMe₂SiC₆H ₄EMe₂C₆H₄SiMe₂H (E = C (10), Si (11), Ge (12), Sn(13)) were prepared by the in situ Grignard reaction of p,p′-BrC₆H₄

Full text of DOI:10.1021/om050265s

Organometallics 2005, 24, 3629-3633
3629
Incorporation of Group 14 Elements into
Siloxane-Bridged Paracyclophanes
cyclo-[p,p′-Me2SiC6H4EMe2C6H4SiMe2O]2
(E ) C, Si, Ge, Sn)§
Jens Beckmann,*,† Andrew Duthie,† Gregor Reeske,†,‡ and Markus Schu¨rmann‡
Centre for Chiral and Molecular Technologies, Deakin University, Geelong 3217, Australia,
and Lehrstuhl fu¨r Anorganische Chemie II, Universita¨t Dortmund,
D-44221 Dortmund, Germany
Received April 8, 2005
The bis(arylene silanes) p,p′-HMe2SiC6H4EMe2C6H4SiMe2H (E ) C (10), Si (11), Ge (12),
Sn(13)) were prepared by the in situ Grignard reaction of p,p′-BrC6H4CMe2C6H4Br, Mg
turnings, and HSiMe2Cl (for 10) and the Grignard reaction using p-HMe2SiC6H4Br, Mg
turnings, and Me2ECl2 (E ) Si for 11, Ge for 12, Sn for 13). The oxidation of 10-13 using
Pearlman’s catalyst, Pd(OH)2/C, in aqueous THF provided the bis(arylene silanols) p,p′-
HOMe2SiC6H4EMe2C6H4SiMe2OH (E ) C (14), Si (15), Ge (16), Sn(17)). The HCl-catalyzed
condensation of 14-17 in highly diluted solutions of acetone/water afforded the siloxane-
bridged paracyclophanes cyclo-[p,p′-Me2SiC6H4EMe2C6H4SiMe2O]2 (6-9) that incorporate
the group 14 elements E ) C, Si, Ge, and Sn. Compounds 6-17 were investigated by
multinuclear solution and solid-state NMR spectroscopy and 6 and 9 also by X-ray
crystallography.
Introduction
The first siloxane-bridged silacyclophanes, namely
2,4,6,8-tetrakis(dimethylsila)-3,7-dioxa-1,5(1,4)dibenz-
enacyclooctaphane (1) and 2,4,6,8-tetrakis(dimethyl-
sila)-3,7-dioxa-1,5(1,3)dibenzenacyclooctaphane (2), were
obtained as byproducts in extremely poor yields (4% and
6%, respectively), during the preparation of poly(tetra-
methyl-para-silaphenylenesiloxane)6 and poly(tetra-
methyl-meta-silaphenylenesiloxane)7 by the n-hexyl-
amine 2-ethylhexoate-catalyzed polycondensation of
para- and meta-bis(dimethylhydroxysilyl)benzene (Chart
1). Under more appropriate reaction conditions (e.g.,
high dilution, use of 4-(dimethylamino)pyridine as
condensation catalyst) the yield of 2 was improved (43%)
and its molecular structure determined by X-ray crys-
tallography.8 During the course of this work, a number
of new siloxane-bridged silacyclophane derivatives,
namely 2,4,6,8,9,11-hexakis(dimethylsila)-3,7,10-trioxa-
1,5(1,3,5)dibenzenabicyclo[3.3.3]undecaphane (3), 2,4,6,8-
tetrakis(dimethylsila)-3,7-dioxa-1,5(1,3)dithiophenacy-
clooctaphane (4), and 2,4,6,8-tetrakis(dimethylsila)-3,7-
dioxa-1,5(1,3)dipyridinacyclooctaphane (5), were prepared
via an alternative route and investigated by X-ray
diffraction (Chart 1).9 This route, which was also
extended to the preparation of 1 and 2, involves the
hydrolytic polycondensation of arene precursors pos-
sessing two or three dimethylchlorosilyl groups and
provides molecular products in fair to good yields (1:
28%, 2: 65%: 3: 15%, 4: 7%, 5: 62%).9 In elegant work,
Silicon-bridged macrocycles1 including silacyclophanes,2
silacalixarenes,3 silacalixquinones,4 and silacrowns5
have attracted considerable attention in recent years
owing to their novel optical and electronic properties and
applications in host-guest chemistry.
§ Dedicated to Professor Hans Hartl on the occasion of his retirement
from The Free University of Berlin.
* Present address: Institut fu¨r Chemie-Anorganische und Ana-
lytische Chemie, Freie Universita¨t Berlin, Fabeckstrasse 34-36, 14195
Berlin, Germany. E-mail: beckmann@chemie.fu-berlin.de.
† Deakin University.
‡ Universita¨t Dortmund.
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10.1021/om050265s CCC: $30.25 © 2005 American Chemical Society
Publication on Web 06/18/2005

3630 Organometallics, Vol. 24, No. 15, 2005
Beckmann et al.
3).12 Compounds 14-17 were obtained as microcrystal-
line colorless solids in very good yields. Although
organosilanols usually show a high degree of crystal-
linity,13 all attempts to grow crystals suitable for X-ray
crystallography failed. The number of magnetically
inequivalent silicon atoms observed in the 29Si MAS
NMR spectra indicated that in all cases at least two
independent molecules are present in the bulk materi-
als.
Chart 1
The HCl-catalyzed condensation of highly dilute solu-
tions of 14-17 in acetone/water provided the desired
siloxane-bridged paracyclophanes cyclo-[p,p′-Me2SiC6H4-
EMe2C6H4SiMe2O]2 (6-9) as crystalline materials in
reasonable to good yields (eq 4).14 The ring size of 6-9
was established by osmometric molecular weight deter-
minations (Chart 1).
The molecular structures of compounds 6 (E ) C) and
9 (E ) Sn) were established by X-ray crystallography
and are shown in Figures 1 and 2; selected crystal data
and bond parameters are collected in Tables 1 and 2.
Both structures lie across a crystallographic center of
inversion, which is consistent with the number of 29Si
MAS NMR signals. The intramolecular distances of the
symmetry-related ring atoms, C1‚‚‚C1a (9.5 Å) and
Si2‚‚‚Si2a (11.1 Å) for 6 and Sn1‚‚‚Sn1a (10.5 Å) and
Si2‚‚‚Si2a (11.7 Å) for 9, demonstrate that the cavities
are nanosized, as opposed to compounds 1-4 (Figures
1 and 2). Although the structures are not isotypes, the
24-membered macrocycles of 6 and 9 adopt very similar
conformations in the solid state. Differences were
observed in the way compounds 6 and 9 are arranged
in the crystal lattice. Molecules of 9 are packed in an
eclipsed fashion, so that the overlaying cavities define
the silacyclophane 1 as well as a phosphorus analogue
of 5 were converted into their radical anions and fully
characterized.10 We now describe a rather mild route
to a new class of siloxane-bridged paracyclophanes,
cyclo-[p,p′-Me2SiC6H4EMe2C6H4SiMe2O]2 (6-9), that
incorporate group 14 elements, E ) C, Si, Ge, and Sn
(Chart 1).
Discussion
The preparation of p,p′-HMe2SiC6H4CMe2C6H4SiMe2H
(10) was achieved by adaptation of the in-situ Grignard
method first reported in the 1960s (eq 1).11 Bis(arylene
silanes) p,p′-HMe2SiC6H4EMe2C6H4SiMe2H (E ) Si
(11), Ge (12), Sn(13)) were prepared using 2 equiv of
the Grignard reagent derived from p-HSiMe2SiC6H4Br
in reactions with Me2SiCl2, Me2GeCl2, and Me2SnCl2,
respectively (eq 2). Compounds 10-13 were isolated by
vacuum distillation in reasonable yields and obtained
as colorless oils.
(10) (a) Cataldo, L.; Choua, S.; Berclaz, T.; Geoffroy, M.; Mezailles,
N.; Ricard, L.; Mathey, F.; Le Floch, P. J. Am. Chem. Soc. 2001, 123,
6654. (b) Mezailles, N.; Maigrot, N.; Hamon, S.; Ricard, L.; Mathey,
F.; Le Floch, P. J. Org. Chem. 2001, 66, 1054. (c) Dutan, C.; Choua,
S.; Berclaz, T.; Geoffrey, M.; Me´zailles, N.; Moores, A.; Ricard, L.; Le
Floch, P. J. Am. Chem. Soc. 2003, 125, 4487.
(11) (a) Beck, H. N.; Chaffee, R. G. J. Chem. Eng. Data 1963, 8,
603. (b) Merker, R. L.; Scott, M. J. J. Am. Chem. Soc. 1963, 85, 2243.
(12) (a) Beckmann, J.; Dakternieks, D.; Duthie, A.; Foitzik, R. C.
Silicon Chem. 2003, 2, 27. (b) Beckmann, J.; Duthie, A.; Reeske, G.;
Schu¨rmann, M. Organometallics 2004, 23, 4630.
(13) (a) Lickiss, P. D. Adv. Inorg. Chem. 1995, 42, 147. (b) Lickiss
P. D. The synthesis and structure of silanols. In Tailor-Made Silicon-
Oxygen Compounds; Corriu R., Jutzi P., Eds.; Vieweg: Braunschweig,
1996; p 47. (c) Lickiss, P. D. Polysilanols. In Organic Silicon Com-
pounds Volume 3; Rappoport Z., Apeloip, Y., Eds.; Wiley: New York,
2001; Chapter 12, p 695. (d) Chandrasekhar, V.; Boomishankar, R.;
Nagendran, S. Chem. Rev. 2004, 104, 5847.
(14) Several condensation catalysts under various reaction condi-
tions were studied to maximize the yields of 6-9. The most suitable
conditions reported herein were adopted from: Omietanski, G. M.
(Union Carbide Corporation) Patent No. 3,187,029, 1965.
Bis(arylene silanols) p,p′-HOMe2SiC6H4EMe2C6H4-
SiMe2OH (14, E ) C; 15, E ) Si; 16, E ) Ge; 17, E )
Sn) were obtained by the catalytic oxidation of the
corresponding bis(arylene silanes) 10-13 in aqueous
THF solutions using Pearlman’s catalyst, Pd(OH)2/C (eq

Siloxane-Bridged Paracyclophanes
Organometallics, Vol. 24, No. 15, 2005 3631
Table 1. Crystal Data and Structure Refinement
for 6 and 9
6
9
formula
fw, g mol-1
cryst syst
cryst size, mm
space group
a, Å
C
38H52O2Si4
C
36H52O2Si4Sn2
653.16
866.52
monoclinic
monoclinic
0.08 × 0.50 × 0.50 0.26 × 0.26 × 0.20
C2/c
P21/c
31.048(4)
9.9074(12)
12.6181(15)
90
7.1771(6)
17.7623(16)
17.1867(13)
90
b, Å
c, Å
R, deg
â, deg
91.957(3)
90
96.152(5)
90
γ, deg
V, Å3
3879.1(8)
4
2178.4(3)
2
Z
F
calcd, Mg m-3
1.118
1.321
T, K
293(2)
293(2)
µ, mm-1
F(000)
0.183
1.283
1408
880
θ range, deg
index ranges
1.3 to 25.0
-36 e k e 36
-11 e l e 11
-11 e h e 15
11 169
3.2 to 27.5
0 e k e 9
0 e l e 22
-22 e h e 22
4942
Figure 1. General view of 6 showing 30% probability
displacement ellipsoids and the crystallographic numbering
scheme. Symmetry operation used to generate equivalent
atoms: a ) 0.5 - x, 0.5 - y, 2 - z.
no. of reflns collcd
completeness to θ max
99.9%
99.0%
no. of indep reflns/Rint 3411
no. of reflns obsd with 2350
I > 2σ(I))
4942
2221
no. refined params
199
199
GooF (F2)
1.039
0.064
0.148
<0.0001
0.758
R1(F) (I > 2σ(I))
wR2(F2) (all data)
(∆/σ)max
0.034
0.088
<0.0001
0.432/-0.736
largest diff peak/hole, 0.253/-0.277
e Å-3
Table 2. Selected Bond Parameters [Å, deg] for 6
and 9a
6
9
C1-C2
1.540(5)
1.540(4)
1.529(4)
1.532(4)
1.611(3)
1.849(5)
1.841(4)
1.856(3)
1.615(3)
1.852(4)
1.846(5)
1.861(4)
108.3(3)
112.2(2)
106.8(2)
105.8 (2)
112.6 (2)
111.1(2)
109.1(2)
109.0(2)
108.3(1)
111.4(2)
110.3(2)
108.7(2)
110.6(2)
109.5(2)
106.8(1)
109.4(2)
111.0(2)
109.7(2)
160.3(2)
Sn1-C2
Sn1-C3
Sn1-C11
Sn1-C21
Si1-O2
2.128(5)
2.106(5)
2.111(6)
2.128(5)
1.603(3)
1.842(5)
1.843(5)
1.855(5)
1.596(3)
1.843(7)
1.861(6)
1.861(5)
110.3(2)
108.6(1)
110.9(1)
111.6(1)
107.5(2)
107.8(1)
109.4(2)
108.8(2)
107.7(2)
111.3(2)
109.5(2)
110.0(2)
110.3(2)
107.3(2)
108.2(2)
111.5(2)
110.1(2)
109.5(2)
159.6(2)
C1-C3
C1-C11
C1-C21
Si1-O2
Si1-C4
Si1-C4
Si1-C5
Si1-C5
Si1-C14
Si2-O2
Si1-C14
Si2-O2a
Si2-C6
Figure 2. General view of 9 showing 30% probability
displacement ellipsoids and the crystallographic numbering
scheme. Symmetry operation used to generate equivalent
atoms: a ) - 1 - x, 1 - y, - z.
Si2-C6
Si2-C7
Si2-C7
Si2-C24
C2-C1-C3
C2-C1-C11
C2-C1-C21
C3-C1-C11
C3-C1-C21
Si2-C24
C2-Sn1-C3
C2-Sn1-C11
C2-Sn1-C21
C3-Sn1-C11
C3-Sn1-C21
C11-Sn1-C21
O2-Si1-C4
O2-Si1-C5
O2-Si1-C14
C4-Si1-C5
C4-Si1-C14
C5-Si1-C14
O2a-Si2-C6
O2a-Si2-C7
O2a-Si2-C24
C6-Si2-C7
C6-Si2-C24
C7-Si2-C24
Si1-O2-Si2a
parallel running nanoporous channels in the crystal
lattice (Figure 3), whereas no such channels were
observed for compound 6.
C11-C1-C21
O2-Si1-C4
O2-Si1-C5
O2-Si1-C14
C4-Si1-C5
C4-Si1-C14
C5-Si1-C14
O2-Si2-C6
O2-Si2-C7
O2-Si2-C24
C6-Si2-C7
C6-Si2-C24
C7-Si2-C24
Si1-O2-Si2
Conclusion
The present work describes a straightforward route
to siloxane-bridged paracyclophanes, cyclo-[p,p′-Me2-
SiC6H4EMe2C6H4SiMe2O]2 (6-9), incorporating the group
14 elements E ) C, Si, Ge, and Sn. Unlike the recently
reported synthesis of compounds 3-5, the preparation
of 6-9 requires no harsh reagents, such as SO2Cl2, and
the intermediates 10-17 are air-stable, as opposed to
some intermediates in the preparation of 3-5, which
are moisture sensitive.9 The shape and lengths of the
organic/organometallic spacers made possible the prepa-
ration of siloxane-bridged paracyclophanes with nano-
scale cavities and channels for the first time. We are
currently investigating strategies to functionalize and
cross-link 6-9 and related compounds to transfer them
into potentially useful materials for applications in
host-guest chemistry.
a Symmetry operation used to generate equivalent atoms: a )
- 1 - x, 1 - y, - z.
Experimental Section
General Procedures. All solvents were distilled prior to
use. 2,2′-Bis(p-bromophenyl)propane15 and p-bromophenyldi-
methylsilane16 were prepared according to known procedures.
The commercial products HSiMe2Cl, Me2SiCl2, Me2GeCl2, Me2-

3632 Organometallics, Vol. 24, No. 15, 2005
Beckmann et al.
12: yield 13.8 g, 37.0 mmol, 74%. Bp: 160 °C, 10-3 Torr. 1H
NMR (CDCl3) δ: 7.86 (4H), 7.82 (4H), 4.79 (2H, 1J(1H-29Si) )
189 Hz), 0.98 (6H), 0.66 (12 H). 13C{1H} NMR (CDCl3) δ: 141.2,
137.6, 133.6, 133.1, -3.2, -3.8. 29Si{1H} NMR (CDCl3) δ:
-16.4. IR (neat, NaCl plates) νSiH: 2118 cm-1. Anal. Calcd for
C18H28GeSi2 (373.22): C, 57.93; H, 7.56. Found: C, 57.82; H,
7.43.
13: yield 10.3 g, 24.5 mmol, 49%. Bp: 200 °C, 10-3 Torr.
1H NMR (CDCl3) δ: 7.70 (8H), 4.61 (2H, 1J(1H-29Si) )
189 Hz), 0.66 (6H, 2J(1H-119Sn) ) 56 Hz), 0.51 (12H). 13C{1H}
NMR (CDCl3) δ: 141.8, 137.6, 135.7, 133.7, -3.8, -10.2
(1J(13C-119Sn) ) 365 Hz). 29Si{1H} NMR (CDCl3) δ: -17.0.
119Sn{1H} NMR (CDCl3) δ: -58.9. IR (neat, NaCl plates) νSiH
:
2118 cm-1. Anal. Calcd for C18H28Si2Sn (419.33): C, 51.56; H,
6.73. Found: C, 51.32; H, 6.71.
Figure 3. Perspective view of 9 along the crystallographic
a-axis.
Synthesis of 2,2-Bis(p-dimethylhydroxysilylphenyl)-
propane (14) and Bis(p-dimethylhydroxysilylphenyl)-
dimethylsilane (15), -germane (16), and -stannane (17).
To an ice-cooled suspension of Pearlman’s catalyst (20 mg) in
THF (50 mL) and water (5 mL) was slowly added a solution
of 10 (3.12 g, 10.0 mmol), 11 (3.29 g, 10.0 mmol), 12 (3.73 g,
10.0 mmol), or 13 (4.19 g, 10.0 mmol) in THF (15 mL). After
the evolution of hydrogen ceased, the reaction mixture was
stirred at room temperature for 15 min. The catalyst was
filtered off, the solvent was removed at 30 °C under reduced
pressure, and ether (50 mL) was added to the residue. Most
of the aqueous layer was removed with a pipet and the solution
dried over Na2SO4. Hexane was added (20 mL) and two-thirds
of the solvents removed at 30 °C under reduced pressure.
Analytical pure products precipitated at -10 °C.
SnCl2, and Pearlman’s catalyst (Pd(OH)2/C, 20 wt % (Pd dry
basis) on carbon, water e 50%) were purchased from Aldrich.
The solution NMR spectra were measured using a JEOL
Eclipse Plus 400 spectrometer (at 399.78 Mz (1H), 100.54 (13C),
79.42 (29Si), and 149.05 (119Sn)) and were referenced against
SiMe4 and SnMe4. The solid-state NMR spectra were measured
using the same instrument equipped with a 6 mm MAS probe.
Crystalline Si(SiMe3)4 (δiso -9.9/-135.6) and c-Hex4Sn (δiso
-97.35) were used as secondary references. The 119Sn MAS
NMR spectra were obtained using cross polarization (contact
time 5 ms, recycle delay 10 s). The IR spectra were recorded
using a BioRad FTIR spectrometer. Microanalyses were car-
ried out by CMAS, Belmont, Australia. Molecular weight
determinations (c ) 10.0 mmol; 40 °C; CHCl3) were carried
out using a Gonotec Osmomat 070 osmometer.
Synthesis of 2,2-Bis(p-dimethylsilylphenyl)propane
(10). A solution of 2,2-bis(p-bromophenyl)propane (8.85 g, 25.0
mol) in THF (50 mL) was slowly added to an ice-cooled
suspension of Mg turnings (2.43 g, 100 mmol) in THF (100
mL) and dimethylchlorosilane (9.46 g, 100 mmol). The reaction
mixture was heated for 1 h at reflux, then poured into ice water
(100 mL) and extracted with ether (2 × 100 mL). The combined
organic extracts were dried over Na2SO4 and the volatiles
removed under reduced pressure. The resultant oil was
purified by Kugelrohr distillation.
14: yield 3.07 g, 8.91 mmol, 89%. Mp: 142-143 °C. 1H NMR
(CDCl3) δ: 7.49 (4H), 7.25 (4H), 1.69 (6H), 0.38 (12H). 13C-
{1H} NMR (CDCl3) δ: 151.9, 135.9, 133.9, 126.3, 43.0, 30.4,
-3.75. 29Si{1H} NMR (CDCl3) δ: 8.1. 29Si{1H} MAS NMR δiso
:
6.2, 5.8, 4.5, 3.4 (approximate ratio 1:1:1:1). IR (KBr) νOH: 3274
cm-1. Anal. Calcd for C19H28O2Si2 (344.60): C, 66.22; H, 8.19.
Found: C, 66.54; H, 8.22.
15: yield 3.07 g, 8.50 mmol, 85%. Mp: 114-116 °C. 1H NMR
(CDCl3) δ: 7.55 (4H), 7.54 (4H), 0.54 (6H), 0.38 (12H). 13C-
{1H} NMR (CDCl3) δ: 139.9, 139.6, 133.5, 132.3, -0.1, -2.6.
29Si{1H} NMR (CDCl3) δ: 7.9, -8.0. 29Si{1H} MAS NMR δiso
:
7.6, 5.9, -7.6, -10.0 (approximate ratio 1:3:1:1). IR (KBr)
νOH: 3264 cm-1 Anal. Calcd for C18H28O2Si3 (360.68): C, 59.94;
H, 7.82. Found: C, 59.79; H, 7.94.
10: yield 5.41 g, 17.3 mmol, 69%. Bp: 135 °C, 10-3 Torr. 1H
NMR (CDCl3) δ: 7.53 (4H), 7.33 (4H), 4.45 (2H, 1J(1H-29Si) )
188 Hz), 1.76 (6H), 0.41 (12H). 13C{1H} NMR (CDCl3) δ: 151.5,
134.1, 133.8, 126.3, 42.9, 30.5, -3.8. 29Si{1H} NMR (CDCl3) δ:
-17.6. IR (neat, NaCl plates) νSiH: 2117 cm-1. Anal. Calcd for
C19H28Si2 (312.60): C, 73.00; H, 9.03. Found: C, 72.96; H, 9.05.
Synthesis of Bis(p-dimethylsilylphenyl)dimethylsi-
lane (11), -germane (12), and -stannane (13). To a Grignard
solution, prepared from p-bromophenyldimethylsilane (32.3 g,
150 mol) and Mg turnings (7.29 g, 300 mmol) in THF (150
mL), was slowly added a solution of dimethylchlorosilane (6.45
g, 50.0 mmol) or dimethylgermanium dichloride (8.68 g, 50.0
mmol) or dimethyltin dichloride (11.0 g, 50.0 mmol) in THF
(50 mL). The reaction mixture was heated for 12 h at reflux,
then poured into ice water (200 mL) and extracted with ether
(2 × 200 mL). The combined organic extracts were dried over
Na2SO4 and the volatiles removed under reduced pressure. The
resultant oil was purified by Kugelrohr distillation.
16: yield 3.72 g, 9.15 mmol, 92%. Mp: 103-117 °C. 1H NMR
(CDCl3) δ: 7.63 (4H), 7.57 (4H), 0.74 (6H), 0.41 (12H). 13C-
{1H} NMR (CDCl3) δ: 141.6, 139.3, 133.0, 132.6, -0.1, -3.3.
29Si{1H} NMR (CDCl3) δ: 7.6. 29Si{1H} MAS NMR δiso: 8.0,
6.5 (approximate ratio 1:3). IR (KBr) νOH: 3271 cm-1. Anal.
Calcd for C18H28GeO2Si2 (405.22): C, 53.35; H, 6.96. Found:
C, 53.46; H, 7.09.
17: yield 2.39 g, 5.29 mmol, 53%. Mp: 99-111 °C. 1H NMR
(CDCl3) δ: 7.61 (8H), 0.58 (6H), 0.41 (12H). 13C{1H} NMR
(CDCl3) δ: 142.3, 139.2, 135.7, 132.7, -0.12, -10.2 1J(13C-
119Sn) ) 365 Hz. 29Si{1H} NMR (CDCl3) δ: 7.2. 119Sn{1H} NMR
(CDCl3) δ: -59.3. 29Si{1H} MAS NMR 7.8, 6.0. 119Sn{1H} MAS
NMR δiso: -57.1. IR (KBr) νOH: 3257 cm-1. Anal. Calcd for
C18H28O2Si2Sn (451.33): C, 47.90; H, 6.25. Found: C, 47.82;
H, 6.36.
Synthesis of 2,8-Bis(dimethyl)-4,6,10,12-tetrakis(di-
methylsila)-5,11-dioxa-1,3,7,9(1,4)tetrabenzenacyclodo-
decaphane (6), 2,4,6,8,10,12-Hexakis(dimethylsila)-5,11-
dioxa-1,3,7,9(1,4)tetrabenzenacyclododecaphane (7), 2,8-
Bis(dimethylgermana)-4,6,10,12-tetrakis(dimethylsila)-
5,11-dioxa-1,3,7,9(1,4)tetrabenzenacyclododecaphane (8),
and 2,8-Bis(dimethylstanna)-4,6,10,12-tetrakis(dimeth-
ylsila)-5,11-dioxa-1,3,7,9(1,4)tetrabenzenacyclodode-
caphane (9). A solution of 14 (1.72 g, 5.00 mmol), 15 (1.80 g,
5.00 mmol), 16 (2.03 g, 5.00 mmol), or 17 (2.26 g, 5.00 mmol)
in acetone (350 mL) was diluted with water (50 mL) and
concentrated HCl (10 µL) was added. The stoppered solution
11: yield 7.56 g, 23.0 mmol, 46%. Bp: 150 °C, 10-3 Torr. 1H
1
NMR (CDCl3) δ: 7.50 (8H), 4.39 (2H, J(1H-29Si) ) 188 Hz),
0.53 (6H), 0.31 (12H). 13C{1H} NMR (CDCl3) δ: 139.1, 138.3,
133.6, 133.4, -2.5, -3.8. 29Si{1H} NMR (CDCl3) δ: -7.7, -16.8.
IR (neat, NaCl plates) νSiH: 2119 cm-1. Anal. Calcd for C18H28-
Si3 (328.67): C, 65.78; H, 8.59. Found: C, 66.62; H, 8.72.
(15) van Walree, C. A.; Roest, M. R.; Schuddeboom, W.; Jenneskens,
L. W.; Verhoeven, J. W.; Warman, J. M.; Kooijman, H.; Spek, A. L. J.
Am. Chem. Soc. 1996, 118, 8395.
(16) Nahlovsky, B.; Chvalovsky, V. Collect. Czech. Chem. Commun.
1968, 33, 3131.

Siloxane-Bridged Paracyclophanes
Organometallics, Vol. 24, No. 15, 2005 3633
was left standing for 3 weeks. During this time a colorless
precipitate formed, which was collected and air-dried. Recrys-
tallization from hexane/dichloromethane afforded crystalline
products.
SADABS.17,18 The structures were solved by direct methods
and difference Fourier synthesis using SHELXS-97 imple-
mented in the program WinGX 2002.19 Full-matrix least-
squares refinement on F2, using all data, was carried out with
anisotropic displacement parameters applied to all non-
hydrogen atoms. Hydrogen atoms were included in geo-
metrically calculated positions using a riding model and were
refined isotropically. The figures were created using DIA-
MOND.20
Crystallographic data (excluding structure factors) have
been deposited at the Cambridge Crystallographic Data Center
as supplementary publication nos. CCDC-271653 (6) and
CCDC-271652 (9). Copies of the information may be obtained
free of charge from the The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (fax: +44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk or www.ccdc.cam.ac.uk).
6: yield 1.29 g, 1.97 mmol, 79%. Mp: 250-251 °C. 1H NMR
(CDCl3) δ: 7.38 (4H), 7.17 (4H), 1.70 (6H), 0.41 (12H). 13C-
{1H} NMR (CDCl3) δ: 151.5, 136.5, 132.8, 126.1, 43.0, 30.7,
1.0. 29Si{1H} NMR (CDCl3) δ: -1.6. 29Si{1H} MAS NMR δiso
:
-2.3, -2.7 (approximate ratio 1:1). Anal. Calcd for C38H52O2-
Si4 (653.18): C, 69.88; H, 8.02. Found: C, 69.90; H, 8.30.
MW: 680 g mol-1
.
7: yield 497 mg, 0.73 mmol, 29%. Mp: 242-243 °C. 1H NMR
(CDCl3) δ: 7.46 (8H), 0.53 (6H), 0.37 (12H). 13C{1H} NMR
(CDCl3) δ: 140.4, 139.0, 133.4, 132.3, 0.9, -2.4. 29Si{1H} NMR
(CDCl3) δ: -8.0, -1.4. 29Si{1H} MAS NMR δiso: -2.0, -2.6, 6.6
(approximate ratio 1:1:1). Anal. Calcd for C36H52O2Si6 (685.33):
C, 63.09; H, 7.65. Found: C, 63.15; H, 7.70. MW: 660 g mol-1
.
Acknowledgment. The Australian Research Coun-
cil (ARC) is thanked for financial support. We are
grateful to Professors D. Dakternieks (Deakin Univer-
sity) and K. Jurkschat (Dortmund University) for sup-
porting this work.
8: yield 1.28 g, 1.65 mmol, 66%. Mp: 243-245 °C. 1H NMR
(CDCl3) δ: 7.55 (4H), 7.52 (4H), 0.71 (6H), 0.45 (12H). 13C-
{1H} NMR (CDCl3) δ: 141.2, 139.8, 133.0, 132.6, 43.0, 1.0,
-3.1. 29Si{1H} NMR (CDCl3) δ: -1.4. 29Si{1H} MAS NMR δiso
:
-2.2, -2.5 (approximate ratio 1:1). Anal. Calcd for C36H52-
Ge2O2Si4 (774.42): C, 55.84; H, 6.77. Found: C, 55.80; H, 6.65.
MW: 730 g mol-1
.
Supporting Information Available: Tables of all coor-
dinates, anisotropic displacement parameters, geometric data
and crystallographic data excluding structure factors (cif files)
for 6 and 9. This material is available free of charge via the
Internet at http://pubs.acs.org.
9: yield 719 mg, 0.83 mmol, 33%. Mp: 239-241 °C. 1H NMR
(CDCl3) δ: 7.69 (4H), 7.48 (4H), 0.96 (6H, J(1H-119Sn) ) 58
2
Hz), 0.47 (12H). 13C{1H} NMR (CDCl3) δ: 139.7, 134.3, 132.9,
127.6, 0.8, -2.2. 29Si{1H} NMR (CDCl3) δ: -1.1. 119Sn{1H}
NMR (CDCl3) δ: -61.4. 29Si{1H} MAS NMR δiso: -2.0, -2.6
(approximate ratio 1:1).119Sn{1H} MAS NMR δiso: -59.1. Anal.
Calcd for C36H52O2Si4Sn2 (866.62): C, 49.89; H, 6.05. Found:
OM050265S
(17) Otwinowski, Z.; Minor, W. Processing of X-Ray Diffraction Data
Collected in Oscillation Mode. In Methods in Enzymology, Volume 276,
Macromolecular Crystallography, Part A; Carter, C. W., Sweet, R. M.,
Eds.; Academic Press: New York, 1997; pp 307-326.
(18) SMART, SAINT, and SADABS, Siemens Analytical X-ray
Instruments Inc.: Madison, WI, 1999.
(19) Farrugia, L. J. J. Appl. Crystallogr. 1997, 20, 565.
(20) (a) Bergerhoff, G.; Berndt, M.; Brandenburg, K. J. Res. Natl.
Inst. Stand. Technol. 1996, 101, 221. (b) DIAMOND V2.1e; Crystal
Impact, K. Brandenburg and M. Berndt GbR, http://www.crystalim-
pact.de.
C, 49.75; H, 5.95. MW: 880 g mol-1
.
Crystallography. Single crystals of 6 and 9 suitable for
X-ray crystallography were obtained by evaporation from
solutions of hexane/dichloromethane. Intensity data were
collected on Bruker SMART Apex CCD (6) and Nonius Kappa
CCD (9) diffractometers with graphite-monochromated Mo KR
(0.7107 Å) radiation. Data were reduced and corrected for
absorption using the programs SAINT, SCALEPACK, and