1796
M. Ronchi et al. / Journal of Organometallic Chemistry 692 (2007) 1788–1798
location, therefore they were omitted). Also the results of
the refinements are reported in Table 2. If the refinement
was stable, anisotropic temperature factors were assigned
to non-hydrogen atoms, but for some carbon atoms of
the solvent molecules this was not possible. Moreover,
geometry restraints were necessary to refine sensible EtOH
molecule positions. The large vibrational amplitudes of
these groups are certainly related to their high volatility
to a mixture of anhydrous EtOH, NaOH and H O, the
amount of para substituted phenyltriethoxysilane [4-RC6-
2
H Si(OEt) ] was added in order to obtain a 1.5 M solution
4
3
(silane/NaOH/H O = 1/1/1). The solution was left under
2
nitrogen stream until the solvent was reduced to half volume
(about 1 h) and compounds 1–4 precipitated from the solu-
tion. The residue was washed and centrifuged three times
with anhydrous n-hexane and dried in vacuo, affording pure
products 1–4.
(
see above), and probably reflect the presence of some
vacancies which very likely occurred during the crystal
manipulation.
4.3.1. Sodium 4-chlorophenylcyclotetrasiloxanolate 1
Starting from (4-ClC H )Si(OEt) (2.004 g, 7.29 mmol)
6
4
3
4
4
2
.2. Synthesis
in EtOH (4.9 ml) with NaOH (291 mg, 7.29 mmol) and
H O (0.13 ml, 7.29 mmol), the pure product 1 (1.10 g,
2
1
.2.1. Synthesis of 4-(triethoxysilyl)bromobenzene
To a stirring solution of 1,4-dibromobenzene (7.0 g,
9.7 mmol) in Et O (100 ml) at 0 ꢁC, a 1.6 M solution of
77.6% yield) was obtained as a white solid. H NMR
(400 MHz, DMSO-d ), d, ppm: 7.62 (d, 2H, o-C H Si),
6
6
4
2
9
7.18 (d, 2H, m-C H Si); Si NMR (79.5 MHz, DMSO-
6 4
2
n-BuLi in n-hexane (18.5 ml, 29.7 mmol) was added. After
2
d ), d, ppm: ꢀ70.3 (s). Anal. Calc. for C H Cl Na O -
6
24 16
4
4
8
h the solution was added via cannula to a stirring solution
Si Æ 3EtOH: C, 39.29; H, 3.71. Found: C, 39.45; H,
4
of ClSi(OEt) (12 ml, 59.4 mmol) in Et O (140 ml) at 0 ꢁC,
3.89%.
3
2
and LiCl immediately precipitated as a white powder. The
reaction was allowed to warm to room temperature and
was left overnight under stirring. The suspension was fil-
tered off through Celite using a G3 filter. The solvent was
removed and the residue was distilled under vacuum afford-
4.3.2. Sodium 4-bromophenylcyclotetrasiloxanolate 2
Starting from (4-BrC H )Si(OEt) (2.10 g, 6.57 mmol)
in EtOH (4.4 ml) with NaOH (263 mg, 6.57 mmol) and
6
4
3
H O (0.12 ml, 6.57 mmol), the pure product 2 (650 mg,
2
1
ing 6.12 g of the pure product as a colorless liquid (66%
41.4% yield) was obtained as a white solid. H NMR
1
yield). H NMR (400 MHz, CDCl ), d, ppm: 7.55 (m, 4H,
(400 MHz, DMSO-d ), d, ppm: 7.56 (d, 2H, o-C H Si),
3
6
6
4
2
9
o-C H Si, m-C H Si), 3.88 (q, 6H, CH ), 1.26 (t, 9H,
7.38 (d, 2H, o-C H Si); Si NMR (79.5 MHz, DMSO-
6 4
6
4
6
4
2
2
9
CH3). Si NMR (79.5 MHz, CDCl ), d, ppm: ꢀ58.3 (s).
d ), d, ppm: ꢀ70.0 (s). Anal. Calc. for C H Br Na O
3
6
24 16
4
4
8-
Si Æ 3EtOH: C, 32.9; H, 3.10. Found: C, 32.22; H,
4
4
.2.2. 4-(Triethoxysilyl)styrene
A solution of 4-bromostyrene (6.54 ml, 50 mmol) in THF
3.23%.
(
5 ml) was added dropwise in 1 h, under rigorous water free
4.3.3. Sodium 4-styryl-phenylcyclotetrasiloxanolate 3
Starting from (4-CH @CHC H )Si(OEt) (2.015 g,
conditions, to a 250 ml round bottom flask, under N atmo-
2
2
6
4
3
sphere, containing magnesium turnings (1.34 g, 55 mmol) in
THF (60 ml). After addition, the reaction mixture was stir-
red for 1 h, then it was stopped to allow a black precipitate
to settle from the solution of styrylmagnesium bromide. The
Grignard reagent was added via cannula in a dropping fun-
7.57 mmol) in EtOH (5.0 ml) with NaOH (303 mg,
7.57 mmol) and H O (0.135 ml, 7.57 mmol), the pure prod-
2
uct 3 (998 mg, 71% yield) was obtained as a cream colored
1
powder. H NMR (400 MHz, DMSO-d ), d, ppm: 7.67 (d,
6
2H, o-C H Si, J
= 7.7 Hz), 7.29 (d, 2H, m-C H Si,
6
4
H–H
6 4
nel and was dropped in a solution of ClSi(OEt) (19.6 ml,
JH–H = 7.7 Hz), 6.68 (m, 1H, CH@, Jcis = 10.9 Hz,
3
1
00 mmol) in THF (50 ml) in half an hour. The resulting
Jtrans = 17.4 Hz), 5.77 (d, 1H, CH @, J
= 17.4 Hz),
Si NMR
2
trans
2
9
mixture was stirred overnight, then the solvent was removed
in vacuo and the product extracted with n-hexane and fil-
tered off on Celite to eliminate the magnesium salts. The
solution was evaporated to dryness and the residue was dis-
5.17 (d, 1H, CH @, Jcis = 10.9 Hz);
2
(79.5 MHz, DMSO-d ), d, ppm: ꢀ70.23 (s). Anal. Calc.
6
for C H Na O Si Æ 2EtOH: C, 51.65; H, 4.78. Found:
3
2
28
4
8
4
C, 51.05; H, 4.60%.
tilled in vacuo, affording the pure product as a colorless
1
liquid (10 g, 75% yield). H NMR (400 MHz, CDCl ), d,
4.3.4. Sodium 4-(chloromethyl)-phenylcyclotetrasiloxanolate
4
3
ppm: 7.67 (d, 2H, o-C H Si, J = 7.9 Hz), 7.45 (d, 2H,
H–H
6
4
m-C H Si, J
= 7.9 Hz), 6.74 (m, 1H, CH@, Jcis
=
=
Starting
from
(4-ClCH C H )Si(OEt)
3
(3.90 g,
6
4
H–H
2
6
4
1
0.9 Hz, Jtrans = 17.6 Hz), 5.83 (d, 1H, CH @, Jtrans
13.5 mmol) in EtOH (9.0 ml) with NaOH (541 mg,
2
1
7.6 Hz), 5.30 (d, 1H, CH @, J = 10.9 Hz), 3.90 (q, 6H,
13.5 mmol) and H O (0.24 ml, 13.5 mmol), the pure prod-
2
cis
2
CH O), 1.27 (t, 9H, CH ).
uct 4 (2.28 g, 80.85% yield) was obtained as a white solid.
2
3
1
H NMR (400 MHz, DMSO-d ), d, ppm: 7.67 (d, 2H,
6
4
.3. Synthesis of sodium cyclotetrasiloxanolates 1–4
o-C H Si), 7.24 (d, 2H, m-C H Si), 4.69 (s, 2H, CH );
6
4
6
4
2
2
9
Si NMR (79.5 MHz, DMSO-d ), d, ppm: ꢀ69.88 (s).
6
Cyclotetrasiloxanolates 1–4 were synthesized according
Anal. Calc. for C H Cl Na O Si Æ 2EtOH: C, 36.49; H,
28 24 4 4 8 4
to the following general procedure: in a typical preparation,
3.09. Found: C, 36.82; H, 3.09%.