Synthesis and structures of tris[2-(dimethylamino)phenyl]silane and -germane compounds

Article abstract of DOI:10.1021/om970548n

Tris[2-(dimethylamino)phenyl]silane and -germane compounds (1 and 2) were synthesized and characterized by X-ray crystallography. Three 2-(dimethylamino)phenyl groups in the hydrosilane (1a) and hydrogermane (1b) encapsulate the hydrogen atom bonded to si

Full text of DOI:10.1021/om970548n

5102
Organometallics 1997, 16, 5102-5107
Syn th esis a n d Str u ctu r es of
Tr is[2-(d im eth yla m in o)p h en yl]sila n e a n d -ger m a n e
Com p ou n d s
Atsushi Kawachi, Yoko Tanaka, and Kohei Tamao*
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611, J apan
Received J une 27, 1997X
Tris[2-(dimethylamino)phenyl]silane and -germane compounds (1 and 2) were synthesized
and characterized by X-ray crystallography. Three 2-(dimethylamino)phenyl groups in the
hydrosilane (1a ) and hydrogermane (1b) encapsulate the hydrogen atom bonded to silicon
and germanium, which results in the short Si-H and Ge-H bonds and an increase in the
s character of the bonds. The silanol (2a ) and germanol (2b) exist as monomers through
the intramolecular hydrogen bonding between the hydroxy group and one of the amino
groups.
Ch a r t 1
In tr od u ction
The ligands in which three coordinating arms are
attached to the central atom have attracted much atten-
tion since they highly stabilize the metal and metalloid
complexes.1 We were interested in the synthesis,
structures, and reactivities of group 14 compounds with
three 2-(dimethylamino)phenyl substituents, in which
the dimethylamino donor sites are linked through the
ortho-phenylene skeleton to the central atom possessing
an M-X functionality (M ) Si, Ge; X ) heteroatoms,
metals), as shown in Chart 1. It is noted that the amino
groups are located at a position where they can interact
not with the central atom (M), but with the neighboring
atom (X). This is different from the structural aspects
of the well-studied 2-[(dimethylamino)methyl]phenyl
analogs,2,3 in which the amino group can coordinate with
the central atom rather than the neighboring atom.
In our synthetic studies of such ligands, we have ob-
tained some related compounds with M-H and M-OH
functionalities, that is, tris[2-(dimethylamino)phenyl]-
silane (1a ), -germane (1b), -silanol (2a ), and -germanol
(2b), and found their structural aspects exerted by the
amino groups interesting. Herein, we report the full
details of the synthesis and structures of 1 and 2,
focused on the fact that (1) the hydrosilane 1a and hy-
drogermane 1b contain the compressed Si-H and
Ge-H bonds and (2) the silanol 2a and germanol 2b
exist as monomers in the solid states through the
intramolecular hydrogen bondings. These aspects are
compared with those of the parent Ph3SiX and the
2-(aminomethyl)phenyl analogs 3.2,3
Resu lts a n d Discu ssion
Syn th esis of Tr is[2-(d im eth yla m in o)p h en yl]si-
la n e (1a ) a n d -ger m a n e (1b). Introduction of three
(dimethylamino)phenyl groups into the silicon and
germanium centers was achieved by use of ortho-
lithiated (dimethylamino)aniline (4), which can be pre-
pared by two methods, orthometalation4 of (dimethy-
lamino)aniline with n-BuLi or the halogen-metal ex-
change5 of 2-(dimethylamino)bromoaniline with n-BuLi.
As shown in Scheme 1, the reaction of tetramethoxysi-
lane with an excess of 4 (5.3 molar amounts) in the
presence of TMEDA in THF at -78 °C gave crude tris-
[2-(dimethylamino)phenyl]methoxysilane (5a ).5b Com-
pared to this, some attempted reactions of chlorosilanes,
(1) For recent examples, see: (a) Gossage, R. A.; McLennan, G. D.;
Stobart, S. R. Inorg. Chem. 1996, 35, 1729. (b) Ray, M.; Golombek, A.
P.; Hendrich, M. P.; Young, V. G., J r.; Borovik, A. S. J . Am. Chem.
Soc. 1996, 118, 6084 and references cited therein.
(2) (a) Brelie`re, C.; Carre´, F.; Corriu, R. J . P.; Royo, G. Organome-
tallics 1988, 7, 1006. (b) Brelie`re, C.; Carre´, F.; Corriu, R. J . P.; Royo,
G.; Man, M. W. C.; Lapasset, J . Organometallics 1994, 13, 307.
(3) Auner, N.; Probst, R.; Hahn, F.; Herdweck, E. J . Organomet.
Chem. 1993, 459, 25.
(4) (a) Aslandis, P.; Grobe, J . Z. Naturforsch. 1983, 38b, 280. (b)
Tacke, R.; Wiesenberger, F.; Lopez-Mras, A.; Sperlich, J .; Mattern, G.
Z. Naturforsch. 1992, 47b, 1370.
(5) (a) Tidwell, J . H.; Buchwald, S. L. J . Am. Chem. Soc. 1994, 116,
11797. (b) Zhang, D.; Liebeskind, L. S. J . Org. Chem. 1996, 61, 2594.
(c) Bailey, W. F.; J iang, X.-L. J . Org. Chem. 1996, 61, 2596.
X Abstract published in Advance ACS Abstracts, November 1, 1997.
S0276-7333(97)00548-7 CCC: $14.00 © 1997 American Chemical Society

Tris[2-(dimethylamino)phenyl]silane and -germane
Organometallics, Vol. 16, No. 23, 1997 5103
Sch em e 1
F igu r e 1. Molecular structure of 1a . The thermal el-
lipsoids are drawn at the 30% probability. Hydrogen atoms,
except for H1 on silicon which is represented by spheres
of arbitrary radius, are omitted for clarity.
Ta ble 1. Selected In ter a tom ic Dista n ces (Å), Bon d
An gles (d eg), a n d Tor sion An gles (d eg) for 1a
a n d 1b
1a (M ) Si)
1b (M ) Ge)
Bond Distances
1.32(2)
such as silicon tetrachloride and trichlorosilane, with 4
under similar conditions afforded complex mixtures. The
reaction of tetramethoxygermane with 4 under similar
conditions gave crude tris[2-(dimethylamino)phenyl]-
methoxygermane (5b). Since the methoxy derivatives
5 were converted into the hydroxy derivatives with silica
gel (vide infra), these compounds were used in the next
reactions without purification.
The reduction of methoxysilane 5a with LiAlH4 in
THF at 40 °C afforded the corresponding hydrosilane
1a in 81% yield (Scheme 1). Reduction of methoxyger-
mane 5b proceeded even at room temperature to give
hydrogermane 1b in 77% yield. Both compounds were
recrystallized from hexane to give colorless crystals,
which are stable in air.
Str u ctu r es of 1a a n d 1b. X-ray crystallographic
analysis of 1a reveals its unique structure, as shown in
Figure 1. The selected bond lengths and angles are
listed in Table 1. As expected, all of the amino groups
are located on the frontal face of the Si1-H1 bond, but
they are highly distorted away from the C3 symmetry
by having the symmetry axis through the Si-H bond.
The three amino groups encapsulate the H1 atom with
the N‚‚‚H atomic distances of 2.87(2)-2.97(2) Å, being
only 0.1-0.2 Å longer than the sum of the van der Waals
radii (H, 1.20 Å; N, 1.55 Å).6 Although the atomic
distances N‚‚‚Si1 (2.975-3.196(2) Å) are shorter than
the sum of the van der Waals radii (3.65 Å), the lone
pair electrons on the nitrogens do not direct toward the
silicon. The Si1-H1 bond length of 1.32(2) Å in 1a is
short due to the encapsulation of the H1 atom by
the amino groups, being 0.17 Å shorter than that of
Ph3SiH (1.491(28) Å)7 and 0.11 Å shorter than the
average value of 1.425 Å for the 450 literature data on
Si-H bonds.8 This value is close to 1.29 Å for the Si-H
bond observed in the silane-containing in-cyclophane9
M1-H1
N1‚‚‚H1
N2‚‚‚H1
N3‚‚‚H1
C1-M1
C9-M1
C17-M1
1.42(3)
2.89(3)
3.12(3)
2.94(3)
1.951(3)
1.958(3)
1.960(3)
2.87(2)
2.97(2)
2.97(2)
1.886(2)
1.883(2)
1.884(2)
Bond Angles
109.0(8)
C1-M1-H1
C9-M1-H1
C17-M1-H1
108(1)
114(1)
112(1)
110.4(8)
114.0(8)
Torsion Angles
1.32(2)
C2-C1-M1-H1
C10-C9-M1-H1
C18-C17-M1-H1
N1-C2-C1-M1
N2-C10-C9-M1
N3-C18-C17-M1
1.42(3)
1.42(3)
1.42(3)
11.2(4)
-1.2(4)
-7.3(4)
1.32(2)
1.32(2)
10.2(2)
-2.2(2)
-8.6(2)
in which the hydrogen atom bonded to the silicon is
enclosed with the cyclophane skeleton.
This structural feature of 1a is also reflected in the
infrared spectra. There is a ν(Si-H) absorption at 2225
cm-1, which is shifted to higher frequency by 100 cm-1
relative to that of Ph3SiH (2125 cm-1 10
and by ca. 50
)
cm-1 relative to that of 3 (2177 or 2189.5 and 2173.3
cm-1).2,3 This result is consistent with the observed
short Si-H bond.
In the 1H and 29Si NMR spectra of 1a , the proton
bonded to silicon resonates at δ 6.37 and the silicon
resonates at δ -31.5 (1J Si-H ) 226 Hz). The deshielding
of the 1H and the shielding of the 29Si compared to those
of Ph3SiH (1H NMR δ 5.77; 29Si NMR δ -17.8; 1J Si-H
)
199 Hz)10 can be explained by the van der Waals effect;11
the steric repulsion between the hydrogen and the
dimethylamino groups causes a decrease in the electron
density on the hydrogen and an increase in the electron
density on the silicon atom. Thus, the 29Si chemical
shift is close to that of 3 in which the silicon center is
[4 + 3] hypercoordinated (1H NMR δ 5.8; 29Si NMR δ
(6) Pauling, L. In The Nature of The Chemical Bond, 3rd ed.; Cornell
University Press: New York, 1960.
(7) Allemand, J .; Gerdil, R. Cryst. Struct. Commun. 1979, 8, 927.
(8) Cambridge Structural Database, Update April 1996; QUEST 3D
and VISTA Version 2.0.
(9) L’Esperance, R. P.; West, A. P., J r.; Engen, D. V.; Pascal, R. A.
J . Am. Chem. Soc. 1991, 113, 2672.
(10) The data were obtained in this work.
(11) Gu¨nter, H. In NMR Spectroscopy: Basic Principles, Concepts,
and Applications in Chemistry 2nd ed.; Wiley: Chichester, England,
1995; pp 94-97.

5104 Organometallics, Vol. 16, No. 23, 1997
Kawachi et al.
F igu r e 2. Molecular structure of 1b. The thermal el-
lipsoids are drawn at the 30% probability. Hydrogen atoms,
except for H1 on germanium which is represented by
spheres of arbitrary radius, are omitted for clarity.
F igu r e 3. Molecular structure of 2a and 2a ′ which are
found as independent molecules in a unit cell. The thermal
ellipsoids are drawn at the 30% probability. Hydrogen
atoms, except for H1 on oxygen which is represented by
spheres of arbitrary radius, are omitted for clarity.
-34.9; 1J Si-H ) 226.4 Hz).3 The Si-H coupling constant
of 1a is larger than that of Ph3SiH (1J Si-H ) 199 Hz),10
which indicates an increase in the s character of the
Si-H bond. The PM3 calculation is consistent with the
NMR data.12 Thus, the natural bond orbital analysis
shows that the s character of the silicon orbital involved
in the Si-H bond in 1a (28.2%) is 4.6% higher than that
of the Si-H bond in Ph3SiH (23.6%).
The X-ray crystallographic analysis of the germanium
analog 1b displays a structure isomorphous to that of
1a , as shown in Figure 2 and Table 1.13 Thus, similar
structural aspects are observed; the Ge1-H1 bond
length of 1.42(3) Å is rather short among the 18 data
reported for Ge-H bonds (1.15-1.70 Å; the mean value
1.526 Å).8,14 Interestingly, tris(o-tolyl)germane,15 where
the methyl groups instead of dimethylamino groups are
bonded to the ortho carbon, has the longest Ge-H bond
of 1.700 Å among the reported data.8
oxygemane 5b was similarly converted into the ger-
manol 2b in 30% yield.17 Recrystallization of 2a and
2b from hexane gave colorless crystals.
Str u ctu r es of 2a a n d 2b. X-ray crystallographic
analysis of 2a shows two independent molecules in the
asymmetric unit, as shown in Figure 3; the other
structure is named 2a ′. The selected bond lengths and
angles are listed in Table 2. Since these data for 2a
and 2a ′ are similar to each other, the discussion will be
presented for 2a only. The most striking feature in the
structure of 2a is the intramolecular hydrogen bonding
between the hydroxy group and one of the amino groups.
Due to the intramolecular hydrogen bonding, 2a is
monomeric, which is in sharp contrast to the tetrameric
form of Ph3SiOH through the intermolecular hydrogen
bondings.18 The N1‚‚‚H1 distance is 1.94(4) Å, and the
N1‚‚‚H1-O1 interatomic distance is 2.713(4) Å, which
is within the normal distance of hydrogen bonding
(N‚‚‚H-O 2.62-2.93 Å).19 The N1‚‚‚H1-O1 angle is
157(4)° and the Si1-O1-H1 angle is 106(3)°. An
electrostatic directionality is another parameter char-
acteristic of the hydrogen bonding. Thus the lone-pair
electrons on N1 clearly point toward H1, that is, the
N1‚‚‚H1 vector is nearly in line with the vector of the
lone pair electrons; three C-N1‚‚‚H1 angles are close
to the tetrahedral values (C2-N1‚‚‚H1 ) 100(1)°, C7-
N1‚‚‚H1 ) 104(1)°, C8-N1‚‚‚H1 ) 113(1)°). It is also
noted that one of the amino groups occupies the region
opposite to the Si-O bond due to the electronic repul-
sion of the lone-pair electrons on the oxygen atom. Such
an arrangement of the amino groups is quite different
from that observed in the hydrosilane 1a .
The short Ge-H bond has also been demonstrated by
other spectroscopic data. The infrared spectrum exhib-
its a ν(Ge-H) at 2140 cm-1, which is 100 cm-1 higher
in frequency than that of Ph3GeH (2037 cm-1 16a
and
)
60 cm-1 higher in frequency than that of 3b (2080
cm-1).2 The proton bonded to germanium resonates at
1
δ 6.72 in the H NMR spectra, which is deshielded in
comparison with the shift of Ph3GeH (δ 5.69)16b and that
of 3b (δ 6.05).2
Syn th esis of Tr is[2-(d im eth yla m in o)p h en yl]sil-
a n ol (2a ) a n d -ger m a n ol (2b). These silanol and ger-
manol compounds were readily obtained from the meth-
oxysilane and -germane 5, as shown in Scheme 1. Thus,
treatment of 5a with a suspension of silica gel in hexane/
ethyl acetate (3/1) at room temperature for 8.5 h gave
the corresponding silanol 2a in 60% yield.17 The meth-
The infrared spectra of 2a shows no well-defined
absorption assigned to the O-H stretching, diagnostic
of the strong intramolecular hydrogen bonding,6 whereas
(12) SPARTAN Version 4.0: Hehre, W. J .; Huang, W. W.; Burke,
L. D.; Shusterman, A. J . A SPARTAN Tutorial Version 4.0; Wave-
function: Irvine, CA, 1995. The geometry of calculated structure of
1a was based on the X-ray crystallographic data.
(13) Such isomorphism between silicon and germanium compounds
has been reported by Corriu et al.2 and Brook et al., see: Brook, A. G.;
Peddle, G. J . D. J . Am. Chem. Soc. 1963, 85, 1869.
(14) The shortest (1.15(9) Å) and the second shortest (1.37(7) Å)
Ge-H bonds have been found in C5H5GeH3, see: Barrow, M. J .;
Ebsworth, E. A. V.; Marjorie, M. H.; Rankin, D. W. H. J . Chem. Soc.,
Dalton Trans. 1980, 603.
(17) For reviews for silanols and germanols, see: (a) Birkofer, L.;
Stuhl, O. In The Chemistry of Organosilicon Compounds; Patai, S.,
Rappoport, Z., Eds.; Wiley: Chichester, U.K., 1989; Chapter 10. (b)
Armitage, D. A. In Comprehensive Organometallic Chemistry II;
Davies, A. G., Ed.; Elsevier Science: Oxford, U.K., 1995; Chapter 1.
Riviere, P.; Riviere-Baudet, M.; Satge, J . In Comprehensive Organo-
metallic Chemistry II; Davies, A. G., Ed.; Elsevier Science: Oxford,
U.K., 1995; Chapter 5.
(15) Cameron, T. S.; Mannan, K. M.; Stobart, S. R. Cryst. Struct.
Commun. 1975, 4, 601.
(16) (a) Cross, R. J .; Glockling, F. J . Organomet. Chem. 1965, 3, 146.
(b) Cross, R. J .; Glockling, F. J . Chem. Soc. 1964, 4125.
(18) Bourne, S. A.; Nassimbeni, L. R.; Skobridis, K.; Weber, E. J .
Chem. Soc., Chem. Commun. 1991, 282.
(19) Stout, G. H.; J ensen, L. H. In X-ray Structure Determination,
Macmillan: New York, 1968, p 303.

Tris[2-(dimethylamino)phenyl]silane and -germane
Organometallics, Vol. 16, No. 23, 1997 5105
Ta ble 2. Selected In ter a tom ic Dista n ces (Å), Bon d An gles (d eg), a n d Tor sion An gles (d eg) for 2a , 2a ′, 2b
a n d 2b′
M ) Si
M ) Ge
2a
2a ′a
2b
2b′a
Bond Distances
0.79(4)
O1-H1
0.82(4)
1.94(4)
0.73(7)
2.06(7)
0.77(6)
2.06(6)
N1‚‚‚H1
N1‚‚‚H1-O1
O1-M1
1.91(4)
2.713(4)
1.642(3)
1.905(4)
1.882(3)
1.873(4)
2.654(4)
1.629(2)
1.893(4)
1.870(3)
1.873(4)
2.734(5)
1.783(3)
1.969(5)
1.941(5)
1.956(5)
2.798(6)
1.791(4)
1.983(5)
1.948(5)
1.945(5)
M1-C1
M1-C9
M1-C17
Bond Angles
156(4)
N1-H1-O1
H1-O1-M1
O1-M1-C1
O1-M1-C9
O1-M1-C17
C2-N1‚‚‚H1
C7-N1‚‚‚H1
C8-N1‚‚‚H1
157(4)
106(3)
105.1(2)
106.2(1)
107.3(2)
100(1)
154(8)
107(6)
105.8(2)
106.9(2)
107.3(2)
106(2)
98(2)
159(6)
101(5)
105.0(2)
104.2(2)
105.1(2)
102(2)
109(3)
105.5(1)
109.0(1)
109.1(2)
103(1)
99(1)
118(1)
104(1)
113(1)
101(2)
114(2)
115(2)
Torsion Angles
15.53
H1-O1-M1-C1
O1-M1-C1-C2
O1-M1-C9-C10
O1-M1-C17-C18
M1-C1-C2-N1
M1-C9-C10-N2
M1-C17-C18-N3
19.32
11.25
21.38
19.7(3)
-72.2(3)
-178.1(3)
8.0(5)
-1.3(4)
-1.6(5)
-10.5(3)
61.4(3)
-176.6(3)
-2.7(5)
1.2(4)
-11.3(5)
61.2(4)
-176.0(4)
-2.7(7)
-0.1(6)
0.6(6)
19.5(5)
-73.4(4)
-179.0(4)
10.4(7)
-2.9(7)
-1.5(6)
0.1(5)
a
All atom labels should be primed (′), as shown in Figures 3 and 4.
to the monomeric forms, which is in sharp contrast to
the widely observed oligomeric forms of silanols.
Exp er im en ta l Section
Gen er a l Rem a r k s. 1H (270 MHz), 13C (67.94 MHz), and
29Si (53.67 MHz) NMR spectra were recorded on a J EOL EX-
270 spectrometer. 1H and 13C chemical shifts were referenced
to internal benzene-d6 (1H, δ 7.200 ppm) and CDCl3 (13C, δ
77.00 ppm). 29Si chemical shifts were referenced to external
tetramethylsilane (0 ppm). Mass spectra were measured at
70 eV on a J EOL J MS-700 mass spectrometer equipped with
a MS-SEPU data processing system. Melting points were
measured with a Yanaco-MP-S3 apparatus and were uncor-
rected. Infrared spectra were recorded on a J ASCO IR-810
spectrophotometer. The elemental analyses were performed
at the Microanalysis Division of Institute for Chemical Re-
search, Kyoto University. Analytical samples were purified
by recrystallization.
N,N-Dimethyl-2-bromoaniline was prepared from 2-bromo-
aniline and iodomethane.2 n-Butyllithium in hexane was
purchased from Wako Pure Chemical Industries. N,N,N′,N′-
Tetramethylethylenediamine (TMEDA) was distilled from
n-butyllithium in hexane (50 mL of a 1.6 M solution per 300
mL of TMEDA). Hexane was distilled under nitrogen from
sodium wire. THF and Et2O were distilled under nitrogen
from sodium benzophenone ketyl or lithium aluminium hy-
dride. Tetramethoxysilane was purchased from Shin-Etsu
Chemical Co., Ltd., and distilled before use.20 Tetramethoxy-
germane was purchased from Gelest, Inc. Silica gel was
purchased from Merck (Kieselgel 60, 70-230 mesh). All
reactions were carried out under an inert atmosphere, unless
otherwise noted.
F igu r e 4. Molecular structure of 2b and 2b′ which are
found as independent molecules in a unit cell. The thermal
ellipsoids are drawn at the 30% probability. Hydrogen
atoms, except for H1 on oxygen which is represented by
spheres of arbitrary radius, are omitted for clarity.
Ph3SiOH, for comparison, exhibits an intense absorption
around 3270 cm-1 10
.
The X-ray crystallographic analysis of 2b shows it to
be isomorphous with 2a . Two independent molecules
are present in the unit cell (Figure 4 and Table 2); the
other structure is named 2b′. A similar intramolecular
hydrogen bonding N‚‚‚HO-Ge is observed. The N‚‚‚H
bond length and the N‚‚‚H-O interatomic distance in
2b are 2.06(7) and 2.734(5) Å, respectively. The infrared
spectra of 2b similarly showed no well-defined absorp-
tion assigned to the O-H stretching.
In conclusion, we have obtained tris[2-(dimethylami-
no)phenyl]silane and -germane which have the com-
pressed Si-H and Ge-H bonds. We have also suc-
ceeded in the introduction of the hydroxy group in the
tris[2-(dimethylamino)phenyl]silane and -germane skel-
etons. The resulting intramolecular hydrogen bonding
between the hydroxy group and the amino group leads
Tr is[2-(dim eth ylam in o)ph en yl]m eth oxysilan e (5a) an d
-ger m a n e (5b). To a solution of N,N-dimethyl-2-bromoaniline
(20) Tetramethoxysilane is a rather toxic compound; its vapors can
cause irreversible blindness. See, for example: (a) Hazards in the
Chemical Laboratory, 5th ed.; Luxon, S. G., Ed.; The Royal Society of
Chemistry: Cambridge, England, 1992; p 603. (b) Stokinger, H. E. In
Patty’s Industrial Hygiene and Toxicology, 3rd ed.; Clayton, G. D.,
Clayton, F. E., Eds.; J ohn Wiley and Sons, Inc.: New York, 1981; Vol.
2B, pp 3036-3038.

5106 Organometallics, Vol. 16, No. 23, 1997
Ta ble 3. Su m m a r y of X-r a y Diffr a ction Da ta
Kawachi et al.
1a
1b
2a
2b
empirical formula
fw
C24H31N3Si
389.61
C24H31N3Ge
434.12
C24H31N3OSi
405.61
C24H31N3OGe
450.12
color, habit
cryst size (mm)
cryst syst
space group
a (Å)
colorless, prismatic
0.40 × 0.30 × 0.20
triclinic
P1h (No. 2)
9.256(1)
17.066(2)
7.744(1)
92.67(1)
114.173(10)
84.423(9)
1110.7(2)
2
colorless, prismatic
0.50 × 0.40 × 0.30
triclinic
P1h (No. 2)
9.350(1)
17.075(3)
7.787(1)
92.81(1)
114.451(9)
84.28(1)
1126.0(3)
2
colorless, prismatic
0.50 × 0.50 × 0.50
monoclinic
P21/c (No. 14)
10.693(2)
27.750(2)
15.635(1)
90.0
92.22(1)
90.0
4635(1)
8
colorless, prismatic
0.50 x 0.40 × 0.20
monoclinic
P21/c (No. 14)
10.798(2)
27.820(2)
15.638(1)
90.0
92.22(1)
90.0
4694.0(9)
8
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
D(calcd) (g/cm3)
1.165
10.21
293
1.280
19.33
293
1.162
10.31
293
1.274
19.07
293
µ (cm-1
)
temp (K)
no. of refns collcd
no. of indep refns
no. of obsd reflns, I > 3σ(I)
no. of variables
R
3538
3305 (Rint ) 0.015)
3048
378
0.038
3579
3346 (Rint ) 0.034)
3069
378
0.043
7494
7073 (Rint ) 0.028)
4879
760
0.054
7582
7159 (Rint ) 0.024)
4766
532
0.044
Rw
0.066
0.069
0.088
0.067
goodness of fit
1.89
1.34
1.49
1.08
(1.90 g, 9.4 mmol) in Et2O (9.5 mL) was added n-butyllith-
ium in hexane (1.69 M, 6.2 mL, 10.4 mmol) at -78 °C. The
reaction mixture was stirred at -78 °C for 2 h to give a solu-
tion of 2-(dimethylamino)phenyllithium (4). To the solution
of 4 was added TMEDA (1.6 mL, 10.4 mmol) at -78 °C, and
then the mixture was warmed to room temperature. The
resulting solution was added to a solution of tetramethoxysi-
lane (0.26 mL, 1.77 mmol) in THF (19 mL) at -78 °C. The
reaction mixture was warmed to ambient temperature over
12 h. After removal of the solvent, the residue was diluted
with benzene (ca. 10 mL) and filtered. The filtrate was
concentrated to give crude 5a (1.70 g). The use of tet-
ramethoxygermane (5.7 mL, 38.7 mmol) in place of tet-
ramethoxysilane gave 5b . These compounds were used in
the next step without further purification. 5a : 1H NMR (C6D6)
δ 2.40 (s, 18H), 3.73 (s, 3H), 7.06-7.31 (m, 9H), 7.88-7.91
(m, 3H); 29Si NMR (C6D6) δ -13.6; MS m/ e 419 (M+, 35),
388 (M+ - OMe, 15), 387 (39), 299 (31), 266 (100), 134 (90),
120 (Me2NC6H4, 58). 5b: 1H NMR (C6D6) δ 2.42 (s, 18H), 3.77
(s, 3H), 7.04-7.30 (m, 9H), 8.01-8.03 (m, 3H); FABMS
m/ e 466 (M+ + 1, 2), 434 (M+ - OMe, 28), 134 (100), 120
(Me2NC6H4, 58).
Tr is[2-(d im eth yla m in o)p h en yl]sila n e (1a ). A THF (1.5
mL) solution of 5a obtained above was added to a suspension
of lithium aluminum hydride (190 mg, 4.9 mmol) in THF (5
mL) at 0 °C. The reaction mixture was heated at 40 °C for 5
h. After the reaction mixture was cooled to room temperature,
it was diluted with THF (10 mL), followed by successive
addition of H2O (0.19 mL), 15% NaOH aqueous solution (0.19
mL), and H2O (0.57 mL) at 0 °C. The resulting suspension
was filtered, and the filtrate was concentrated to give a solid.
Recrystallization from hexane gave 1a as a colorless crystal
(557 mg, 81% yield based on tetramethoxysilane). Mp: 91.5-
92.5 °C. 1H NMR (C6D6): δ 2.59 (s, 18H), 6.38 (s, 1H), 6.94-
6.99 (m, 3H), 7.07-7.10 (m, 3H), 7.20-7.30 (m, 3H), 7.35-
7.39 (m, 3H). 13C NMR (CDCl3): δ 45.73, 119.26, 123.32,
129.96, 133.62, 137.32, 160.49. 29Si NMR (C6D6): δ -31.5
(1J Si-H ) 226 Hz). IR (KBr, cm-1): ν(Si-H) 2225. MS: m/ e
389 (M+, 13), 268 (82), 134 (65), 120 (Me2NC6H4, 100). Anal.
Calcd for C24H31N3Si: C, 73.99; H, 8.02; N, 10.79. Found: C,
73.87; H, 8.14; N, 10.80.
7.40-7.43 (m, 3H). 13C NMR (CDCl3): δ 45.70, 119.30, 123.40,
129.49, 135.58, 136.55, 159.42. IR (KBr, cm-1): ν(Ge-H) 2140.
MS: m/ e 435 (M+, 0.1), 314 (25), 120 (Me2NC6H4, 100). Anal.
Calcd for C24H31N3Ge: C, 66.40; H, 7.20; N, 9.68. Found: C,
66.31; H, 7.23; N, 9.66.
Tr is[2-(d im eth yla m in o)p h en yl]sila n ol (2a ). Crude 5a
(2.47 g) was diluted with hexane/ethyl acetate (3/1, 35 mL).
To the solution was added silica gel (30 mL) in one portion,
and the suspension was stirred at room temperature for 8.5 h
in the air. The suspension was filtered with ethyl acetate and
THF, and then the filtrate was concentrated to give a solid.
Recrystallization from hexane gave 3 as a colorless crystal (564
mg, 60% yield based on tetramethoxysilane). Mp: 77.0-77.5
°C. 1H NMR (C6D6): δ 2.48 (s, 18H), 7.03-7.11 (m, 6H), 7.20-
7.29 (m, 3H), 7.77-7.80 (m, 3H). 13C NMR (CDCl3): δ 46.20,
120.32, 123.81, 130.14, 134.86, 137.18, 160.38. 29Si NMR
(C6D6): δ -13.5. MS: m/ e 405 (M+, 45), 388 (M+ - OH, 14),
285 (100), 134 (96), 120 (Me2NC6H4, 71). Anal. Calcd for
C
24H31N3OSi: C, 71.07; H, 7.70; N, 10.36. Found: C, 71.27;
H, 7.77; N, 10.38.
Tr is[2-(d im eth yla m in o)p h en yl]ger m a n ol (2b). In
a
similar manner, 2b was obtained from tetramethoxygermane
in 30% overall yield. Mp: 97.0-98.0 °C. 1H NMR (C6D6): δ
2.42 (s, 18H), 5.19 (s, 1H), 7.04-7.12 (m, 6H), 7.20-7.25 (m,
3H), 7.95-7.99 (m, 3H). 13C NMR (CDCl3): δ 46.17, 120.29,
124.01, 129.96, 136.12, 136.17, 159.07. MS: m/e 451 (M+, 0.1),
434 (M+ - OH, 14), 134 (89), 120 (Me2NC6H4, 100). Anal.
Calcd for C24H31N3OGe: C, 64.04; H, 6.94; N, 9.33. Found:
C, 63.97; H, 7.00; N, 9.27.
X-r a y Str u ctu r e Deter m in a tion s for 1a , 1b, 2a , a n d 2b.
All crystal data and refinement parameters are summarized
in Table 3. Data were collected on a Rigaku AFC7R diffrac-
tometer with graphite-monochromated Cu KR radiation using
the ω-2θ scan technique (2θmax ) 120°). The structure was
solved by heavy-atom Patterson methods,21 expanded using
2
Fourier techniques,22 and refined on |F| . Empirical absorption
corrections based on azimutual scans of several reflections
(21) PARTY: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bos-
man, W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla,
C. The DIRDIF program system. Technical Report of the Crystal-
lography Laboratory; University of Nijmegen: Nijmegen, The Neth-
erlands, 1992.
(22) DIRDIF92: Beurskens, P. T.; Admiraal, G.; Beurskens, G.;
Bosman, W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.;
Smykalla, C. The DIRDIF program system. Technical Report of the
Crystallography Laboratory; University of Nijmegen: Nijmegen, The
Netherlands, 1992.
Tr is[2-(dim eth ylam in o)ph en yl]ger m an e (1b). This com-
pound was obtained from tetramethoxygermane in 89% yield
in essentially the same manner as above except that the
reduction was carried out at room temperature for 11 h. Mp:
96.5-97.5 °C. 1H NMR (C6D6): δ 2.57 (s, 18H), 6.72 (s, 1H),
6.94-6.99 (m, 3H), 7.07-7.10 (m, 3H), 7.20-7.28 (m, 3H),

Tris[2-(dimethylamino)phenyl]silane and -germane
Organometallics, Vol. 16, No. 23, 1997 5107
were applied for the germanium compounds 1b and 2b. The
non-hydrogen atoms were refined anisotropically. All hydro-
gen atoms bonded to carbon atoms were located at the expected
positions by a geometrical calculation and fixed at these posi-
tions. The hydrogen atoms bonded to Si in 1a , Ge in 1b, and
O in 2a and 2b were found on the difference Fourier map and
refined isotropically.
Y.T. thanks the J apan Society for the Promotion of
Science (Fellowship for J apanese J unior Scientists).
Su p p or tin g In for m a tion Ava ila ble: Text giving the
experimental details of the X-ray crystallography, tables of
experimental details, bond distances and angles, torsion
angles, atomic coordinates and B values, and anisotropic
thermal parameters, and ORTEP diagrams of 1a , 1b, 2a , 2a ′,
2b, and 2b′ (98 pages). Ordering information is given on any
current masthead page.
Ack n ow led gm en t. We thank the Ministry of Edu-
cation, Science, Sports and Culture, J apan, for a Grant-
in-Aid for Scientific Research (Grant No. 07405043).
OM970548N