Synthesis, structure, and reactivity of disilanes containing one neutral [4 + 2]-coordinate silicon center

Article abstract of DOI:10.1016/S0022-328X(01)01385-7

[4 + 2]-Coordinate disilanes containing two 8-dimethylamino-1-naphthyl (8-Me₂N-1-Np) groups on the same silicon atom, (8-Me₂N-1-Np)₂XSi-SiMe₃, where X = F, OH, OEt, and H, are prepared. The X-ray structures of t

Full text of DOI:10.1016/S0022-328X(01)01385-7

Journal of Organometallic Chemistry 643–644 (2002) 479–486
www.elsevier.com/locate/jorganchem
Synthesis, structure, and reactivity of disilanes containing one
neutral [4+2]-coordinate silicon center
Kohei Tamao *, Masahiro Asahara, Atsushi Kawachi, Akio Toshimitsu
Institute for Chemical Research, Kyoto Uni6ersity, Uji, Kyoto 611-0011, Japan
Received 30 August 2001; accepted 16 October 2001
Dedicated with admiration and respect to Professor Dr Franc¸ois Mathey in honor of his scientific achievements
Abstract
[4+2]-Coordinate disilanes containing two 8-dimethylamino-1-naphthyl (8-Me2N-1-Np) groups on the same silicon atom,
(8-Me2N-1-Np)2XSi-SiMe3, where X=F, OH, OEt, and H, are prepared. The X-ray structures of the two derivatives, X=F and
OH, show that one of the coordinated dimethylamino groups is anti to the electronegative X group, while the other is anti to the
trimethylsilyl group. The [4+2]-coordinate disilanes (X=F or OEt) are found to be thermally stable under these conditions such
that the corresponding [4+1]-coordinate disilanes (8-Me2N-1-Np)XMeSi-SiMePh2 (X=F or OEt) readily undergo degradation.
In the presence of Pd(PPh3)4 as a catalyst, the [4+2]-coordinate disilane (X=F) undergoes degradation to generate naphthylsi-
lane (8-Me2N-1-Np)-SiMe3, the reaction pathway being different from that of the [4+1]-coordinate disilane (X=F) which
affords the fluorosilane, F-SiMePh2. © 2002 Elsevier Science B.V. All rights reserved.
Keywords: [4+2]-Coordinate silicon compound; Disilane; 8-Dimethylamino-1-naphthyl group; Thermolysis; Transition metal catalyst
disilanes containing one [4+1]-coordinate silicon cen-
ter which have recently been reported to be highly
reactive toward a-elimination (Eq. (1)) during thermol-
ysis [4] or the reaction with a transition metal catalyst
[5]. We report herein the syntheses and structure of
disilanes containing one [4+2]-coordinate silicon cen-
ter which bear two 8-dimethylamino-1-naphthyl groups
and an electronegative group or a hydrogen atom. As
for their reactivity, it is found that: (1) these [4+2]-co-
ordinate disilanes, except for hydroxydisilane, are ther-
mally stable under these conditions such that
[4+1]-coordinate disilanes readily undergo thermal
degradation, and (2) the a-elimination from the [4+2]-
coordinate fluorodisilane proceeds by the reaction with
a palladium catalyst to afford the 8-dimethylamino-1-
naphthyltrimethylsilane, the reaction pathway being
different from that of the [4+1]-coordinate fluorodisi-
lane which affords fluorosilane under the same
conditions.
1. Introduction
The syntheses, structure, and reactivity of hexacoor-
dinate organosilicon compounds have been extensively
studied [1]. However, little has been reported on the
structure and reactivity of neutral hexacoordinate
organosilicon compounds bearing a silicon–silicon
bond [2]. We are interested in the structure and reactiv-
ity of disilanes containing one [4+2]-coordinate [3]
silicon center in order to compare them with those of
Scheme 1.
(1)
* Corresponding author. Tel.: +81-774-383180; fax: +81-774-
383186.
E-mail address: tamao@scl.kyoto-u.ac.jp (K. Tamao).
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01385-7

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K. Tamao et al. / Journal of Organometallic Chemistry 643–644 (2002) 479–486
trifluoro-2,2,2-trimethyldisilane was allowed to react
with two molar amounts of 8-dimethylamino-1-naph-
thyllithium [6] to give the [4+2]-coordinate fluorodisi-
lane (1). The [4+2]-coordinate hydrodisilane (2) was
prepared by the reduction of 1 with LiAlH4 [7]. The
hydrodisilane (2) was converted into the chlorodisilane
by treatment with PCl5 [8]. Due to its high moisture
sensitivity, the chlorodisilane was subjected to ethanoly-
sis or hydrolysis without isolation to afford the [4+2]-
coordinate ethoxydisilane (3) or hydroxydisilane (4),
respectively. The tetracoordinate counterparts 5–8 were
also prepared in similar ways as shown in Scheme 2.
Scheme 2.
2.2. X-ray crystal structures of [4+2]-coordinate
fluorodisilane (1) and hydroxydisilane (4)
The X-ray crystal structures of the [4+2]-coordinate
fluorodisilane (1) and hydroxydisilane (4) are shown in
Figs. 1 and 2, respectively. Selected interatomic dis-
tances and angles as well as dihedral angles are listed in
Table 1.
The geometry around Si1 in 1 and 4, bearing the two
8-dimethylamino-1-naphthyl groups, is deformed from
the tetrahedral to pseudo-octahedral. The distances be-
tween the silicon atom and the coordinated nitrogen
atom are somewhat longer than the normal coordina-
Fig. 1. Crystal structure of 1 drawn at the 30% probability level. All
hydrogen atoms are omitted for clarity.
,
tion distances (52.8 A) [1c]. The distances of N1···Si1,
which is anti to the fluorine atom or hydroxy group, are
shorter than that of N2···Si1, which is anti to the silyl
group. The stronger coordination of N1 to Si1 than
that of N2 seems to result in a higher deformation of
the naphthalene ring of C1ꢀC10 than that of C13ꢀC20.
Thus, the dihedral angles of C1C2C3/C6C7C8 are
greater than C13C14C15/C18C19C20 and those of
Si1C1C8/N1C1C8 are greater than Si1C13C20/
Table 1
,
Selected interatomic distances (A), angles (°), and dihedral angles (°)
for 1 and 4
1 (X=F)
4 (X=OH)
Fig. 2. Crystal structure of 4 drawn at the 30% probability level. All
hydrogen atoms except for H(1) are omitted for clarity.
Interatomic distances
N1···Si1
2.843(3)
2.949(3)
1.632(2)
2.361(2)
1.885(3)
1.884(4)
2.934(2)
3.021(2)
1.670(2)
2.3777(8)
1.892(2)
1.905(2)
N2···Si1
Si1ꢀX1
Si1ꢀSi2
Si1ꢀC1
2. Results and discussion
Si1ꢀC13
2.1. Synthesis of [4+2]-coordinate disilanes and their
tetracoordinate counterparts
Interatomic angles
N1···Si1ꢀX1
N2···Si1ꢀSi2
164.72(8)
169.8(1)
93.24(9)
167.72(8)
177.41(5)
99.08(7)
Si2ꢀSi1ꢀX1
The [4+2]-coordinate fluorodisilane (1), hydrodisi-
lane (2), ethoxydisilane (3), and hydroxydisilane (4),
which contain two 8-dimethylamino-1-naphthyl groups
and a functional group (fluorine or hydrogen atom, or
ethoxy or hydroxy group) on the same silicon atom
were synthesized as shown in Scheme 1. Thus, 1,1,1-
Dihedral angles
C1ꢀC2ꢀC3/C6ꢀC7ꢀC8
Si1ꢀC1ꢀC8/N1ꢀC1ꢀC8
C13ꢀC14ꢀC15/C18ꢀC19ꢀC20
Si1ꢀC13ꢀC20/N2ꢀC13ꢀC20
6.46
20.82
1.19
12.49
35.05
8.89
1.59
18.79

K. Tamao et al. / Journal of Organometallic Chemistry 643–644 (2002) 479–486
481
Table 2
[12], and the downfield shift of that without electroneg-
ative substituents [13].
29Si-NMR data of [4+2]-coordinate and tetracoordinate disilanes
a
a
b
l
l
Dl
2.4. Thermal reacti6ity of [4+2]-coordinate disilanes
(X=F)
(X=H)
(X=OEt)
(X=OH)
1
2
3
4
−5.6
−19.9
−9.8
5
6
7
8
17.5
−36.6
2.2
−23.1
+16.7
−12.0
−7.6
The [4+2]-coordinate fluorodisilane (1), hydrodisi-
lane (2), and ethoxydisilane (3) were found to be ther-
mally stable under such conditions as in xylene at
145 °C for 48 h, in sharp contrast to the [4+1]-coordi-
nate fluoro- or ethoxy-disilanes which readily undergo
a-elimination of the fluoro- or ethoxy-silane under
milder conditions to afford the amine-coordinated
silylene [4]. The tetracoordinate counterparts 5–7 were
also stable under similar conditions.
The [4+2]-coordinate hydroxydisilane (4) underwent
thermal degradation of a different type; thus, when
heated in toluene at 110 °C for 42 h under an argon
atmosphere, 1-(dimethylino)naphthalene was obtained
as the sole volatile product in 94% yield (based on one
aminonaphthyl group in 4), probably due to the proto-
desilylation on the naphthyl carbon atom induced by
the acidic hydrogen of the hydroxy group.
The [4+2]-coordinate disilanes had been expected to
be thermally less stable to a-elimination to generate
amine-coordinated silylenes than the corresponding
[4+1]-coordinate disilanes, because the higher coordi-
nation usually weakens all bonds around the silicon
atom. The unexpected results described above would be
ascribed to the geometry of the [4+2]-coordinate sili-
con center being unfavorable for the a-elimination.
Thus, the two amino groups located in the cis positions
of the pseudo-octahedral geometry in 1–3 must rear-
range to the trans positions to afford the stable struc-
ture of the silylene species bearing two amino groups at
the axial positions of the trigonal bipyramidal struc-
ture. Another reason may reside in an orbital–symme-
try problem during the a-elimination process. For a
complete understanding, much remains to be studied;
one of the attractive trials may be the generation of the
silylenes from the [4+2]-coordinate silicon compound
in which two amino groups are located at trans posi-
tions [14].
−7.2
0.4
a Chemical shift of the silicon atom attached to the naphthyl
carbon.
b Sign (−) indicates the up-field shift.
N2C13C20. Whereas, the Si1ꢀSi2 distances of 2.361(1)
and 2.3777(8) A are in the range of the normal values
of 2.33–2.37 A [9], the Si1ꢀF1 length of 1.632(2) A is
slightly longer than those in the ordinary tetracoordi-
nate fluorosilanes (1.55–1.60 A) [9] and similar to the
one in [4+1]-coordinate fluorodisilane [4c].
It should be noted that no hydrogen bonding is
observed in this [4+2]-coordinate hydroxydisilane (4)
in the solid state in contrast to the fact that intramolec-
ular [10] or intermolecular [11] hydrogen bonding is
observed in some silanols containing the SiꢀSi bond.
,
,
,
,
2.3. NMR spectra of [4+2]-coordinate disilanes
Coordination of the amino group to the silicon atom
in the [4+2]-coordinate fluorodisilane (1) and ethoxy-
disilane (3) in solution has been supported by the
1H-NMR measurements. Thus, at room temperature in
1
C6D6, four broad singlets are observed in the H-NMR
spectra due to the four methyl groups on the two
nitrogen atoms both in 1 and 3. These results indicate
that the coordination of the amino group to silicon in 1
and 3 is strong enough to prevent equilibration of the
two methyl groups on each nitrogen via rotation
around the nitrogen–naphthyl carbon bond on the
NMR time scale. However, only two N-methyl signals
1
are observed in the H-NMR spectra of the [4+2]-co-
ordinate hydrodisilane (2) and hydroxydisilane (4).
The 29Si-NMR chemical shifts summarized in Table 2
also support the coordination of the amino group in
solution. Thus, in 1, 3, and 4, bearing an electronega-
tive substituent (F, OEt, and OH) on the silicon atom
connected to the 8-dimethylamino-1-naphthyl group,
the signal due to the silicon atom appears in a signifi-
cantly higher magnetic field (7–23 ppm) as compared
with that of the tetracoordinate counterpart, 5, 7, and
8. On the other hand, in 2, bearing no electronegative
substituent, the silicon atom connected to the 8-
dimethylamino-1-naphthyl group resonates in a signifi-
cantly lower field as compared with the tetracoordinate
counterpart 6. There have been reported many prece-
dents of the upfield shift of a signal for the hypercoor-
dinate silicon atom bearing electronegative substituents
2.5. Transition metal-catalyzed degradation of
[4+2]-coordinate fluorodisilane (1) and hydrodisilane
(2)
The reactivity of the SiꢀSi bond in the [4+2]-coordi-
nate fluorodisilane (1) toward palladium catalysts has
been examined in view of the ready Pd(0)-catalyzed
degradation of the analogous [4+1]-coordinate fluoro-
disilane affording the corresponding fluorosilane due to
the cleavage of the SiꢀSi and SiꢀF bonds (Si/F a-elimi-
nation) [5b]. As shown in Scheme 3 and Table 3, the
reaction of 1 with a catalytic amount of Pd(PPh3)4 (0.05

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K. Tamao et al. / Journal of Organometallic Chemistry 643–644 (2002) 479–486
as usually observed with ordinary tetracoordinate disi-
lanes [16]. Instead, other bonds are also cleaved pre-
sumably due to the activation by hypercoordination,
resulting in a-elimination such as SiꢀF, SiꢀC, and SiꢀH.
3. Experimental
3.1. General remarks
1H (270 MHz), 13C (67.94 MHz), 19F (254.19 MHz),
29Si (53.67 MHz)-NMR spectra were recorded on a
Scheme 3.
1
JEOL JNM-EX270 spectrometer. H and 13C chemical
shifts are referenced to internal benzene-d6 (1H l 7.20
ppm and 13C l 128.0 ppm). 19F and 29Si chemical shifts
are referenced to external CFCl3 (0 ppm) and Me4Si (0
ppm), respectively. Mass spectra were measured at 70
mol. amt.) at 110 °C in the presence of dipheny-
lacetylene (2 mol. amt.) afforded a different type of
Si/C a-elimination product, 8-dimethylamino-1-naph-
thyltrimethylsilane (9), in the yield of 89%, due to the
cleavage of the SiꢀSi and Siꢀnaphthyl carbon bonds
[15]. In the absence of diphenylacetylene, the yield of 9
was found to decrease (entries 1 and 2). This reaction
also proceeded in the presence of other Pd(0) complexes
as catalysts (entries 3 and 4). No reaction was observed
with the tetracoordinate fluorodisilane (5) under similar
conditions to those of entry 1 (Table 3) but at a higher
temperature (145 °C), indicating the higher reactivity
of the [4+2]- and [4+1]-coordinate fluorodisilanes
toward palladium catalysts.
The [4+2]-coordinate hydrodisilane (2) underwent
another type of Pd(0)-catalyzed degradation in the pres-
ence of diphenylacetylene to afford the hydrosilation
product 10 in 42% yield, together with the Si/C a-elim-
ination product 9 in 14% yield, as shown in Scheme 3.
The former hydrosilation reaction is accompanied by
cleavage of the SiꢀSi bond, and thus, may be regarded
to include the formal Si/H a-elimination. We have
previously reported that the Si/H a-elimination is also
included in the Ni(0)-catalyzed reaction of an
analogous [4+1]-coordinate hydrodisilane with
diphenylacetylene [5a].
eV on
a JEOL JMS-DX300 mass spectrometer
equipped with a JMA-3500 data processing system.
Melting points were measured with a Yanaco-MP-S3
apparatus. Elemental analyses were performed at the
Microanalysis Division of Institute for Chemical Re-
search, Kyoto University. Analytical samples were
purified by recrystallization or HPLC, equipped with a
20×250 mm Wakosil-5Si1-column (Wako). Column
chromatography was performed using Kieselgel (70–
230 mesh) (Merck). THF and Et2O were distilled under
a nitrogen atmosphere from sodium–benzophenone.
Hexane, toluene, and xylene were distilled under a
nitrogen atmosphere from sodium. Benzene was dis-
tilled under a nitrogen atmosphere from LiAlH4.
3.2. 1,1,1-Trifluoro-2,2,2-trimethyldisilane [17]
To anhydrous zinc fluoride powder (29.4 g; 281.5
mmol) was added dropwise 1,1,1-trichloro-2,2,2-
trimethyldisilane [18] (13 g; 62.5 mmol) at 0 °C under
argon atmosphere. When the mixture was allowed to
warm to room temperature (r.t.), an exothermic reac-
tion started. After 2 h, the exothermic reaction was no
longer observed and the title compound (9.1 g; 92%
yield) was collected in a cold trap (−78 °C) under
reduced pressure (25 mmHg). 1H-NMR (C6D6): l
−0.10 (q, J=2.4 Hz, 9H). 19F-NMR (C6D6, CFCl3): l
−120.0.
In conclusion, the SiꢀSi bonds in the [4+2]- and
[4+1]-coordinate disilanes are more labile to cleavage
than that in the tetracoordinate disilanes during the
reaction with a transition metal catalyst. However, the
two silicon centers do not simply add to the acetylene
Table 3
Pd(0)-catalyzed reaction of [4+2]-coordinate fluorodisilane (1)
Entry Catalyst (mol. amt.)
Trapping agent (mol. amt.)
Solvent
Temperature (°C)
Time (h)
Yield of 9
1
2
3
4
Pd(PPh3)4 (0.05)
Pd(PPh3)4 (0.05)
Pd(OAc)2 (0.03) t-BuNC(0.5)
Pd(dba)2 (1)
PhCꢁCPh (2)
Xylene
Xylene
110
110
48
48
37
11
89
–
34 a
81
PhCꢁCH (1.2)
–
Toluene 70
THF Room temperature
82
a Forty percent conversion.

K. Tamao et al. / Journal of Organometallic Chemistry 643–644 (2002) 479–486
483
3.3. 1-Fluoro-1,1-bis(8-dimethylamino-1-naphthyl)-
2,2,2-trimethyldisilane (1)
3.5. 1-Ethoxy-1,1-bis(8-dimethylamino-1-naphthyl)-
2,2,2-trimethyldisilane (3)
To a suspension of 8-dimethylamino-1-naphthlyl-
lithium etherate [6] (7.22 g; 28.7 mmol) in dry ether (42
ml) was added dropwise 1,1,1-trifluoro-2,2,2-trimethyl-
disilane (2.27 g; 14.5 mmol) at −70 °C under stirring.
The mixture was allowed to warm to r.t. and stirred
overnight. The reaction mixture was concentrated in
vacuo, and dissolved in benzene (30 ml) and hexane (10
ml), and the precipitates were filtered through a sintered
glass-filter. The filtrate was concentrated in vacuo to
leave solids which crystallized on standing in hexane (7
ml) at −25 °C. Recrystallization from hexane at
−25 °C afforded 1 (5.1 g, 11.1 mmol; 77%) as colorless
To a solution of 2 (443 mg; 1.0 mmol) in benzene (6
ml) was added PCl5 (109 mg; 0.5 mmol) at r.t. and the
resulting yellow solution was stirred for 3 h. The mix-
ture was concentrated in vacuo. To the residue were
added successively ether (8 ml), triethylamine (0.56 ml,
4 mmol), and ethanol (0.12 ml, 2 mmol), and the
resulting mixture was stirred for 3 h. After removal of
volatile materials in vacuo, dry benzene (5 ml) was
added and the precipitates were filtered through a sin-
tered glass-filter. The filtrate was concentrated, fol-
lowed by addition of hexane (3 ml) and filtration. The
filtrate was concentrated to afford white solids. Recrys-
tallization of the solids from hexane afforded 3 (295
mg, 0.6 mmol; 60%) as colorless solids. This compound
was so sensitive to moisture that the hydrolyzed com-
pound, hydroxydisilane (4), was present as a contami-
1
crystals: m.p. 112.5–114 °C. H-NMR (C6D6): l 0.18
(s, 9H), 1.17 (bs, 3H), 1.81 (bs, 3H), 2.23 (bs, 3H), 2.74
(bs, 3H), 6.82 (bd, J=7.3 Hz, 1H), 7.14–7.25 (m, 3H),
7.48–7.58 (m, 4H), 7.72–7.78 (m, 2H), 8,32 (bd, J=5.7
Hz, 1H), 8.51 (bd, J=5.1 Hz, 1H). 13C-NMR (C6D6):
l 0.9, 44.6, 46.1, 50.3, 116.2, 119.9, 125.1, 125.5, 126.1,
126.4, 126.6, 128.8, 130.3, 133.6 (d, J=9.8 Hz), 134.1,
135.1, 135.4, 136.0, 152.5, 154.1 (five signals were not
1
nant as detected by the NMR spectroscopy. H-NMR
(toluene-d6): l 0.06 (s, 9H), 1.12 (t, J=7 Hz, 3H), 1.17
(bs, 3H), 1.66 (bs, 3H), 2.32 (bs, 3H), 2.66 (bs, 3H),
3.05–3.2 (m, 1H), 3.5–3.65 (m, 1H), 6.92 (bs, 1H),
7.1–7.2 (m, 2H), 7.45–7.6 (m, 5H), 7.6–7.8 (m, 2H),
8.3–8.4 (m, 1H), 8.7–8.8 (m, 1H). 29Si-NMR (C6D6): l
−16.7, −9.8. Anal. Calc. for C29H38N2OSi2: C, 71.55;
H, 7.87; N, 5.75. Found: C, 71.45; H, 8.02; N, 5.84%.
found). 19F-NMR (C6D6):
(C6D6): l −21.4 (d, JFꢀSi=43 Hz), −5.6 (d, JFꢀSi
l
−145.4. 29Si-NMR
2
1
=
292 Hz). Anal. Calc. for C27H33FN2Si2: C, 70.39; H,
7.22; N, 6.08. Found: C, 70.24; H, 7.26; N, 6.20%.
3.6. 1-Hydroxy-1,1-bis(8-dimethylamino-1-naphthyl)-
2,2,2-trimethyldisilane (4)
3.4. 1,1-Bis(8-dimethylamino-1-naphthyl)-
2,2,2-trimethyldisilane (2)
To a solution of 2 (94 mg; 0.21 mmol) in benzene (3
ml) was added PCl5 (23 mg; 0.11 mmol) at r.t. and the
resulting yellow solution was stirred for 20 min. The
mixture was concentrated in vacuo. To the residue was
added a saturated aqueous solution of NaHCO3 (10
ml). After the extraction with ether, the organic layer
was concentrated and the residual oil was purified by
silica gel chromatography (hexane–EtOAc=10:1, Rf
0.21). Recrystallization from hexane–EtOAc gave 4 (74
mg; 0.16 mmol; 77% yield) as colorless crystals. M.p.
To a mixture of 1-fluorodisilane (1) (922 mg; 2.0
mmol) and LiAlH4 (76 mg; 2.0 mmol) ether was added
(10 ml) at 0 °C under a nitrogen atmosphere. The
reaction mixture was warmed to r.t. and stirred for 4.5
h, followed by the addition of EtOAc (0.78 ml, 8.0
mmol) at 0 °C over 10 min. After stirring for 30 min,
the precipitates were filtered through a sintered glass-
filter and the filtrate was concentrated. Ether (1 ml) and
hexane (10 ml) were added to the residue, and the
filtration/concentration operation was repeated to af-
ford white solids. Recrystallization of the solids from
hexane afforded 2 (724 mg, 1.64 mmol; 82%) as color-
less crystals: m.p. 109–110 °C. 1H-NMR (C6D6): l
0.15 (s, 9H), 1.84 (bs, 6H), 2.15 (s, 6H), 5.78 (s, 1H),
7.01 (d, J=7.6 Hz, 2H), 7.25 (d, J=7.6 Hz, 2H), 7.44
(dd, J=7.0 and 8.1 Hz, 2H), 7.55 (dd, J=1.0 and 8.1
Hz, 2H), 7.61 (dd, J=1.4 and 8.1 Hz, 2H), 8.26 (dd,
J=1.4 and 7.0 Hz, 2H). 13C-NMR (C6D6): l 0.8, 45.1,
49.6, 117.5 (bs), 125.4, 125.7, 126.0, 129.8, 134.6, 135.3,
135.5, 136.3, 153.4. 29Si-NMR (C6D6): l −19.9 (d,
1JSiꢀH=172 Hz), −15.6. Anal. Calc. for C27H34N2Si2:
C, 73.25; H, 7.74; N, 6.33. Found: C, 73.07; H, 7.64; N,
6.24%.
1
117.5–118.5 °C. H-NMR (C6D6): l 0.19 (s, 9H), 2.03
(s, 6H), 2.09 (s, 6H), 7.00 (d, J=7.6 Hz, 2H), 7.24 (d,
J=7.8 Hz, 2H), 7.46 (dd, J=7.3 and 8.1 Hz, 2H), 7.52
(d, J=7.8 Hz, 2H), 7.73 (d, J=7.8 Hz, 2H), 8.38 (d,
J=6.8 Hz, 2H). 13C-NMR (C6D6): l 0.8, 46.6, 49.2,
117.9, 125.3, 125.6, 126.6, 129.6, 134.9, 135.8, 135.9,
137.7, 153.4. 29Si-NMR (C6D6): l −16.4, −7.2. Anal.
Calc. for C27H34N2OSi2: C, 70.69; H, 7.47; N, 6.11.
Found: C, 70.41; H, 7.48; N, 6.08%.
3.7. 1-Fluoro-1,1-di(1-naphthyl)-2,2,2-trimethyldisilane
(5)
In a similar manner to that described for the prepara-
tion of 1, 1,1,1-trifluoro-2,2,2-trimethyldisilane (333

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K. Tamao et al. / Journal of Organometallic Chemistry 643–644 (2002) 479–486
mg; 2.1 mmol) was allowed to react with a solution of
1-naphthyllithium (4.0 mmol) in ether, prepared from
1-bromonaphthalene and n-butyllithium in ether. The
mixture was allowed to warm to r.t. and stirred
overnight. Filtration, concentration and recrystalliza-
tion from THF–hexane afforded 365 mg (47% yield) of
5 as white solids: m.p. 158–159 °C. 1H-NMR (C6D6): l
0.25 (s, 9H), 7.18–7.27 (m, 6H), 7.61–7.65 (m, 2H),
7.69 (d, J=8.4 Hz, 2H), 8.02 (dd, J=1.1 and 6.8 Hz,
2H), 8.41–8.45 (m, 2H). 13C-NMR (C6D6): l −1.3,
125.5, 126.2, 126.6, 128.8 (d, J=2.4 Hz), 129.3, 131.4,
134.0, 134.8, 135.0 (d, J=4.9 Hz), 137.3. 19F-NMR
(C6D6): l −176.2. 29Si-NMR (C6D6): l −19.1 (d,
2H), 8.11 (dd, J=1.1 and 6.5 Hz, 2H), 8.52 (d, J=7.0
Hz, 2H). 13C-NMR (C6D6): l −0.4, 18.7, 60.4, 125.6,
126.0, 126.1, 129.2, 129.2, 130.8, 134.0, 135.6, 136.1,
137.7. 29Si-NMR (C6D6): l −19.8, 2.2. Anal. Calc. for
C25H28OSi2: C, 74.94; H, 7.04. Found: C, 74.84; H,
7.09%.
3.10. 1-Hydroxy-1,1-di(1-naphthyl)-2,2,2-
trimethyldisilane (8)
To a suspension of 1-naphtlyllithium (5 mmol) in
ether (10 ml) was added 1,1,1-trichloro-2,2,2-trimethyl-
disilane (529 mg; 2.5 mmol) at 0 °C and the resulting
mixture was stirred for 1 h. After removal of solvents,
benzene (5 ml) was added and the precipitates was
filtered through a sintered glass-filter. The filtrate was
concentrated under reduced pressure and the residual
oil was dissolved in ether (5 ml). To this solution was
added a saturated aqueous solution of NaHCO3 (20
ml). After the extraction with ether, the organic layer
was concentrated and the residual oil was purified by
silica gel chromatography (hexane–EtOAc=10:1, Rf
0.19) to give 8 (852 mg, 2.29 mmol; 91% yield) as a
colorless solid: m.p. 74–76 °C. 1H-NMR (C6D6): l
0.24 (s, 9H), 7.15–7.26 (m, 4H), 7.31 (dd, J=7.0 and
8.1 Hz, 2H), 7.67 (dd, J=1.9 and 7.6 Hz, 2H), 7.72 (d,
J=8.1 Hz, 2H), 8.01 (dd, J=1.1 and 6.8 Hz, 2H), 8.40
(d, J=7.6 Hz, 2H). 13C-NMR (C6D6): l −1.0, 125.6,
125.9, 126.1, 129.1, 129.2, 130.7, 134.0, 135.0, 137.2,
137.4. 29Si-NMR (C6D6): l −19.3, 0.4. Anal. Calc. for
C23H24OSi2: C, 74.14; H, 6.49. Found: C, 74.35; H,
6.65%.
1
2JFꢀSi=26.9 Hz), 17.5 (d, JFꢀSi=317 Hz). HRMS calc.
for C23H23FSi2: m/e 374.1322. Found: m/e 374.1333.
Anal. Calc. for C23H23FSi2: C, 73.75; H, 6.19. Found:
C, 73.98; H, 6.24%.
3.8. 1,1-Di(1-naphthyl)-2,2,2-trimethyldisilane (6)
In a similar manner to that described for the prepara-
tion of 2, the reaction of 5 (100 mg, 0.27 mmol) with
LiAlH4 (8 mg, 0.21 mmol) in Et2O (2 ml), subsequent
work up, and recrystallization from hexane afforded
pure 6 as colorless crystals (83 mg, 0.23 mmol; 87%):
m.p. 147–148 °C. 1H-NMR (C6D6): l 0.26 (s, 9H),
5.98 (s, 1H), 7.22–7.26 (m, 6H), 7.64–7.67 (m, 2H),
7.69 (d, J=8.1 Hz, 2H), 7.93 (dd, J=1.1 and 6.8 Hz,
2H), 8.35–8.39 (m, 2H). 13C-NMR (C6D6): l −0.4,
125.7, 126.0, 126.3, 129.0, 129.3, 130.6, 133.2, 134.0,
1
136.7, 138.0. 29Si-NMR (C6D6): l −36.6 (d, JSiꢀH
=
180 Hz), −16.7. Anal. Calc. for C23H24Si2: C, 77.47; H,
6.78. Found: C, 77.31; H, 6.86%.
3.11. Attempted thermal degradation of 1 in solution
3.9. 1-Ethoxy-1,1-di(1-naphthyl)-2,2,2-trimethyldisilane
(7)
A solution of 1 (13 mg; 0.028 mmol) in dry toluene-
d8 (0.55 ml) was sealed in an NMR sample tube under
argon atmosphere. After heating of the tube at 110 °C
for 19 h and 145 °C for 1 h, no change was observed
To a suspension of 1-naphtlyllithium (6 mmol) in
ether (12 ml) was added 1,1,1-trichloro-2,2,2-trimethyl-
disilane (624 mg; 3 mmol) at −60 °C. The mixture was
allowed to warm to −20 °C during the period of 1 h
with stirring. To the reaction mixture containing 1-
1
based on the H-NMR measurement.
3.12. Thermal degradation of 4 in solution
chloro-1,1-di(1-naphthyl)-2,2,2-trimethyldisilane
and
LiCl were added dropwise triethylamine (1.3 ml; 9
mmol) and ethanol (0.42 ml, 7.2 mmol) at 0 °C. The
mixture was stirred for 18 h at r.t. After the removal of
volatile materials, hexane (10 ml) was added to the
residue and the precipitates were filtered through a
sintered glass-filter. The filtrate was concentrated under
reduced pressure and the residual oil was purified by
silica gel chromatography (hexane–EtOAc=10:1, Rf
0.49) to afford 7 (1.04 g, 2.6 mmol; 86%) as a colorless
A solution of 4 (74 mg; 0.16 mmol) in toluene (2 ml)
was heated at 110 °C for 43 h under argon atmosphere.
Complete disappearance of 4 was confirmed by 1H-
NMR analysis. After removal of solvent, column chro-
matography of the residual oil on silica gel gave
N,N - dimethyl - 1 - naphthylamine (hexane–EtOAc=
10:1, Rf 0.39) (26 mg, 0.15 mmol; 94% yield).
3.13. The reaction of 1 with Pd(PPh3)4 in the presence
of diphenylacetylene
1
solid: m.p. 73–75 °C. H-NMR (C6D6): l 0.29 (s, 9H),
1.15 (t, J=7.0 Hz, 3H), 3.73 (q, J=7.0 Hz, 2H),
7.13–7.24 (m, 4H), 7.33 (dd, J=7.0 and 8.1 Hz, 2H),
7.66 (dd, J=2.2 and 7.3 Hz, 2H), 7.73 (d, J=8.4 Hz,
A mixture of 1 (230 mg, 0.5 mmol), diphenyl-
acetylene (178 mg, 1.0 mmol), and Pd(PPh3)4 (29 mg,

K. Tamao et al. / Journal of Organometallic Chemistry 643–644 (2002) 479–486
485
Table 4
(10 mg; 14% yield) and 1,2-diphenyl-1-trimethylsi-
lylethene 10 (hexane–EtOAc=10:1, Rf=0.50) (32 mg,
0.13 mmol; 42%): 1H-NMR (C6D6): l 0.18 (s, 9H),
6.90–7.22 (m, 11H). MS: m/e 252 [M+, 100], 237
[M+ꢀMe, 77],178 [M+ꢀSiMe3ꢀH, 22]%.
Crystal data for structure determination of 1 and 4
1
4
Chemical formula
Formula weight
Crystal size (mm)
Crystal system
C27H33N2FSi2
460.74
0.4×0.4×0.2
Triclinic
C
458.75
0.5×0.5×0.6
Monoclinic
P2/n (no. 14)
27H34ON2Si2
3.15. X-ray crystallography
Space group
P1 (no. 2)
Crystals of 1 and 4 suitable for X-ray study were
grown from hexane and hexane–AcOEt, respectively.
Intensity data were collected on a Rigaku AFC7R
diffractometer using an ꢀ−2q scan technique to a
maximum 2q value of 120.1°. The data were corrected
for Lorentz polarization effects. A correction for sec-
ondary extinction was applied (coefficient=3.64184e−
05 (1) and 4.42886e−06 (4)). The structure was solved
by direct methods (SAPI91) [19] and expanded using
Fourier techniques (DIRDIF92) [20]. The non-hydrogen
atoms were refined anisotropically. Hydrogen atoms
were refined isotropically. The final cycle of full-matrix
least-squares refinements were based on 3093 observed
reflections (I\3.00|(I)) and 422 variable parameters
for 1 and 3217 observed reflections (I\3.00|(I)) and
426 variable parameters for 4 (Table 4). All calculations
were performed using the TEXSAN crystallographic
software package of Molecular Structure Corporation
[21].
Unit-cell dimensions
,
a (A)
9.301(2)
17.900(7)
8.788(2)
95.71(2)
117.22(1)
77.41(2)
1269.8(6)
2
14.233(1)
10.021(1)
18.650(1)
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
110.105(7)
3
,
V (A )
Z
2498.0(4)
4
1.220
20
zcalc (g cm−3
)
1.205
20
Temperature (°C)
Radiation
,
Cu–Ka (u=1.54178 A)
14.55
3786
v (Cu–Ka) (cm−1
)
14.48
3965
3217 (I\3.00|(I))
426
0.043
0.066
1.57
Unique reflections
Reflections used
Number of variables 422
R
RW
3093 (I\3.00|(I))
0.063
0.088
2.28
Goodness-of-fit on
F2
0.025 mmol) in dry xylene (3 ml) was heated at 110 °C
for 48 h under argon atmosphere. Complete disappear-
ance of 1 was confirmed by H-NMR analysis. The
4. Supplementary data
1
reaction mixture was filtered through Celite 545 and the
filtrate was concentrated. Column chromatography of
the residual oil on silica gel gave 8-(dimethylamino)-1-
naphthyltrimethylsilane (9) (hexane–EtOAc=10:1,
Rf=0.61) (108 mg, 0.44 mmol; 89%), together with a
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Center, CCDC no. 167387 for compound 1 and
CCDC no. 167388 for compound 4. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (Fax: +44-1233-336033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
1
trace amount of N,N-diethyl-1-naphthylamine. 9: H-
NMR (C6D6): l 0.43 (s, 9H), 2.34 (s, 6H), 7.08 (dd,
J=7.3 and 1.1 Hz, 1H), 7.31 (t, J=7.6 Hz, 1H), 7.34
(dd, J=8.1 and 7.3 Hz, 1H), 7.54 (dd, J=8.1 and 1.1
Hz, 1H), 7.69 (dd, J=8.1 and 1.1 Hz, 1H), 7.96 (dd,
J=6.8 and 1.1 Hz, 1H). Anal. Calc. for C15H21NSi: C,
74.01; H, 8.70; N, 5.75. Found: C, 73.87; H, 8.79; N,
5.65%.
Acknowledgements
We thank the Ministry of Education, Culture,
Sports, Science and Technology, Japan, for the grant-
in-aid 09239103 as well as that for COE Research on
Elements Science, No. 12CE2005.
3.14. The reaction of 2 with Pd(PPh3)4 in the presence
of diphenylacetylene
A mixture of 2 (133 mg; 0.3 mmol), dipheny-
lacetylene (160 mg; 0.9 mmol), and Pd(PPh3)4 (17 mg;
0.015 mmol) in dry xylene (1.8 ml) was heated at
145 °C for 36 h under argon atmosphere. Almost com-
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Celite 545 and the filtrate was concentrated. Column
chromatography of the residual oil on silica gel gave 9

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