Crystalline aminoorganosilanes - Syntheses, structures, spectroscopic properties

Article abstract of DOI:10.1002/zaac.201300646

A number of aminosilanes derived from N-methylaniline and chloroorganylsilanes were prepared and characterized. X-ray structure analysis was performed on the crystalline derivatives Ph(Cl)Si(NMePh)₂ (4a), HSi(NMePh)₃ (2b), MeSi(NMePh)₃ (3b), and Ph ₂Si(NMePh)₂ (6b). The compounds were comprehensively characterized by ¹H, ¹³C, ²⁹Si NMR, and IR spectroscopy. Volatile derivatives were further characterized by GC/MS. It was shown using quantum chemical methods that the planarization of the nitrogen atoms in the amino derivatives is caused by phenyl groups and silyl substituents. Copyright

Full text of DOI:10.1002/zaac.201300646

Job/Unit: Z13646
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Date: 01-04-14 10:02:49
Pages: 8
ARTICLE
DOI: 10.1002/zaac.201300646
Crystalline Aminoorganosilanes – Syntheses, Structures, Spectroscopic
Properties
Birgit Meinel,[a] Betty Günther,[b] Anke Schwarzer,[b] and Uwe Böhme*[b]
Dedicated to Dr. Wilhelm Seichter on the Occasion of His 65th Birthday
Keywords: Aminosilane; Synthesis; Crystal structure analysis; X-ray diffraction; Quantum chemical calculations
Abstract. A number of aminosilanes derived from N-methylaniline terized by 1H, 13C, 29Si NMR, and IR spectroscopy. Volatile deriva-
and chloroorganylsilanes were prepared and characterized. X-ray tives were further characterized by GC/MS. It was shown using quan-
structure analysis was performed on the crystalline derivatives tum chemical methods that the planarization of the nitrogen atoms in
Ph(Cl)Si(NMePh)2 (4a), HSi(NMePh)3 (2b), MeSi(NMePh)3 (3b), and the amino derivatives is caused by phenyl groups and silyl substituents.
Ph2Si(NMePh)2 (6b). The compounds were comprehensively charac-
Introduction
Results and Discussion
N-methylaniline was utilized previously in our group to ob-
tain crystalline aminoorganodisilanes.[17,18] Preparative access
to aminomonosilanes with N-methylaniline is given by the re-
action of the respective amine and a chlorosilane in the pres-
ence of triethylamine as “HCl catcher” instead of an excess of
the amine.
Scheme 1 shows the compounds synthesized including the
applied pathways. The reaction of N-methylaniline with chlo-
roorganosilanes in the presence of triethylamine results in dif-
ferent amino-substituted organomonosilanes. The chloro-
organomonosilanes, the amount of starting materials, and the
isolated products are summarized in Table 1.
An excess of N-methylaniline was applied to achieve the
replacement of all chlorine atoms in the molecule. The substi-
tution of all chlorine atoms was only successful for the reaction
with dichlorodimethylsilane to form 5b. All other main prod-
ucts have at least one chlorine atom bound to the silicon. An
explanation for this limitation could be the reduced reactivity
of chloro(N-methylanilino)organosilanes in combination with
steric effects.
Aminosilanes with a Si–N bond have attracted considerable
interest due to their potential applications. They are valuable
source materials for synthesis of silicon carbo-nitride films[1,2]
and allow access to high performance silicon based ceram-
ics.[3,4] Furthermore, chlorine containing organosilicone poly-
mers can be cured with alkylamines leading to crosslinked sila-
zane polymers.[5] Several amino(chloro)silanes are reported
mostly as liquids at room temperature[6–9] and as starting mate-
rials for different reactions, e.g. for cyclic bis(amino)germyl-
enes, -stannylenes, and -plumbylenes.[10] Ammonolysis of di-
organodichlorosilanes in the presence of sodium leads to the
formation of silazanes.[11] The reaction of aminochlorosilanes
with chlorotrimethylsilane gives aminotri- and tetrasilanes[12]
or disilanes in the presence of lithium.[13] Finally, N-substi-
tuted ethylenediamines and SiCl4 form mono- and poly-
(spiro)cyclic aminosilanes of small molecular masses, which
are precursors for Si3N4 layers.[14]
Another reaction is the insertion of CO2 into the SiN bond
of aminosilanes yielding carbomoyloxysilanes of the type
Me2Si[(OCO)NR2]2.[15,16] It might be possible to gain further
insight into the mechanism of CO2 insertion by using solid
aminosilanes. Therefore, our intention was to synthesize a
series of crystalline aminosilanes and to determine their X-ray
structures.
As shown in Table 1 only two out of six of the chlorinated
intermediates are solids at room temperature, namely 2a and
4a. The growth of single crystals was only successful for 4a
from n-pentane solution at 8 °C. The crystallographic data is
summarized in the Experimental Section, and Table 2 gives the
relevant geometric parameters. Compound 4a crystallizes in
* Dr. U. Böhme
Fax: +49-3731-39-4058
¯
the triclinic space group P1 with one independent molecule in
E-Mail: Uwe.Boehme@chemie.tu-freiberg.de
[a] Fakultät für Naturwissenschaften
BTU Cottbus-Senftenberg
the asymmetric unit (Figure 1). The Cs symmetry of the mo-
lecule itself is not represented in the solid state. All bond
lengths of the silicon atoms are in the range of classical cova-
lent single bonds. As expected, the silicon atom shows a tetra-
hedral environment (109.4° on average). Specifically, the
angles are slightly distorted varying from 104.69 (C1–Si1–
Großenhainer Straße 57
01968 Senftenberg, Germany
[b] Institut für Anorganische Chemie
Technische Universität Bergakademie Freiberg
Leipziger Straße 29
09599 Freiberg, Germany
Z. Anorg. Allg. Chem. 0000, ᭿,(᭿), 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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B. Meinel, B. Günther, A. Schwarzer, U. Böhme
ARTICLE
Table 2. Selected geometric parameters /Å,° for compounds 4a, 2b,
3b and 6b.
4a
Si1–N2
Si1–N1
Si1–C1
Si1–Cl1
N1–C8
N1–C7
N2–C15
N2–C14
1.713(2)
1.721(2)
1.856(2)
2.0754(8)
1.413(3)
1.463(3)
1.417(3)
1.469(3)
N2–Si1–N1
N2–Si1–C1
N1–Si1–C1
N2–Si1–Cl1
N1–Si1–Cl1
C1–Si1–Cl1
C8–N1–C7
C8–N1–Si1
C7–N1–Si1
111.76(9)
111.64(9)
112.6(1)
106.57(7)
109.16(7)
104.69(7)
115.9(2)
124.1(1)
119.9(1)
C15–N2–C14 116.3(2)
C15–N2–Si1
C14–N2–Si1
N1–Si1–N1i
N1–Si1–N1ii
N1i–Si1–N1ii
C1–N1–C7
C1–N1–Si1
C7–N1–Si1
N3–Si1–N1
N3–Si1–N2
N1–Si1–N2
N3–Si1–C1
N1–Si1–C1
N2–Si1–C1
C3–N1–C2
C3–N1–Si1
C2–N1–Si1
C10–N2–C9
C10–N2–Si1
C9–N2–Si1
123.9(1)
119.8(2)
109.47(5)
109.47(5)
109.47(5)
117.0(2)
2b
3b
Si1–N1
Si1–N1i
Si1–N1ii
N1–C1
N1–C7
1.727(2)
1.727(2)
1.727(2)
1.409(2)
1.460(2)
121.7(1)
121.2(1)
Si1–N3
Si1–N1
Si1–N2
Si1–C1
N1–C3
N1–C2
N2–C10
N2–C9
N3–C17
N3–C16
1.732(1)
1.744(1)
1.746(1)
1.866(1)
1.411(1)
1.471(1)
1.409(1)
1.468(1)
1.412(1)
1.470(1)
107.82(5)
106.86(5)
108.65(5)
111.54(5)
111.50(5)
110.31(5)
116.30(9)
123.51(7)
120.13(8)
116.23(9)
123.18(8)
120.59(8)
C17–N3–C16 116.61(9)
C17–N3–Si1
C16–N3–Si1
N2–Si–N1
N2–Si–C1
N1–Si–C1
N2–Si–C7
N1–Si–C7
C1–Si–C7
C14–N1–C13 115.5(1)
C14–N1–Si
C13–N1–Si
C21–N2–C20 115.2(1)
C21–N2–Si
C20–N2–Si
124.24(8)
118.79(8)
109.04(7)
107.24(7)
109.08(7)
109.62(7)
110.92(6)
110.85(7)
Scheme 1. Synthetic route to compounds 1a–4a, 6a, 7a, and 1b–7b
studied.
6b
Si–N2
Si–N1
Si–C1
Si–C7
N1–C14
N1–C13
N2–C21
N2–C20
1.742(1)
1.749(1)
1.870(1)
1.872(1)
1.412(2)
1.469(2)
1.413(2)
1.476(2)
Cl1) to 111.76° (N2–Si1–N1) due to asymmetric substitution.
The substituents surrounding the nitrogen atom are in a planar
coordination, this is caused by the conjugative interaction of
the free electron pair at nitrogen with the ipso-substituted aro-
matic ring. The sum of the bond angles around the nitrogen
atoms are 359.9 to 360.0°.
Compound 4a does not possess any relevant hydrogen
atoms bonded to typical hydrogen donors such as oxygen or
nitrogen.[19,20] Therefore, typical hydrogen bonds are absent.
Table 3 shows the C–H···π contacts that form intermolecular
strands.[21]
124.43(9)
120.0(1)
125.5(1)
118.9(1)
Symmetry transformations used to generate equivalent atoms:
(i): –y+2, x–y+1, z; (ii): –x+y+1, –x+2, z.
Table 1. Summary of silanes, the ratio of the starting materials, the isolated products, and the yields for the reaction with N-methylaniline and
lithium N-methylanilide.
Isolated compound
Used silane
Ratio
Yield /%
State of matter
silane:HNMePh
1:5
1:2
1:4
1a
2a
3a
4a
5b
6a
7a
SiCl4
HSiCl3
MeSiCl3
PhSiCl3
Me2SiCl2
Ph2SiCl2
MePhSiCl2
74
48
43
19
41
57
48
oil
solid
oil
solid
solid
oil
1:3.3
1:3.5
1:2.5
1:2.5
silane:LiNMePh
1:4.1
1:3.1
1:1.1
1:1.1
1:1.2
1:2.3
oil
1b
2b
3b
4b
6b
7b
SiCl4
HSiCl3
3a
traces
solid
solid
solid
solid
solid
solid
a)
6
63
traces
56
4a
6a
7a
59
a) The yield is given for the last fraction of 2b containing only traces of 2a.
2
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Crystalline Aminoorganosilanes
Table 3. Geometrical parameters /Å,° for intermolecular interactions in compounds 4a, 2b, 3b, and 6b. Values are given without standard
deviations for clarity.
a)
Atoms involved
Symmetry
d(X···A)
d(C···A)
θ(C–X···A)
4a
C3–H3···Cg3
C5–H5···Cg2
C7–H7C···Cg1
C6–H6···Cg1
C4–H4···Cg5
C18–H18···Cg4
C5–H5···Cg6
–x, –y, 1–z
1–x, 1–y, 1–z
–x, 1–y, 1–z
1/3–y, 2/3+x–y, –1/3+z
–1/2 + x, 1/2–y, –1/2+z
2–x, –y, 1–z
2.81
2.96
2.98
2.90
2.77
2.83
2.77
3.6195
3.7229
3.6991
3.7132
3.5567
3.5831
3.5411
146
140
133
146
141
137
140
2b
3b
6b
1/2–x, 1/2 –y, –z
a) Cg is defined as the centroid of the rings (center of gravity): Cg1: C1–C6, Cg2: C8–C13, Cg3: C15–C20; Cg4: C10–C15; Cg5: C17–C22;
Cg6: C14–C19.
tallize with C1 symmetry in the space groups P21/n and C2/c,
respectively. The space group symmetry of 2b deserves further
attention since this compound crystallizes in the non-centro-
symmetric trigonal space group R3. The molecule itself is not
chiral, but crystallizes in a chiral form with a threefold axis
going through the silicon hydrogen bond. The asymmetric part
of the unit cell contains only the Si–H unit and one N-methyl-
anilino moiety. The comparison of the molecule structures of
2b, 3b, and 6b shows common and typical structural features
for this type of aminoorganosilanes. All compounds are based
on a central tetrahedral silicon atom (2b: 109.5°, 3b: 109.4°,
6b: 109.5°, in average). Again, the nitrogen atoms show planar
environment. The sum of the bond angles at the nitrogen atoms
are 359.6 to 360.0° (Figure 2).
Due to the absence of hydrogen atoms bonded to typical
Figure 1. Molecular structure of compound 4a including numbering
hydrogen donors no relevant hydrogen interactions occur. In-
stead, the crystal packing of 2b, 3b, and 6b is dominated by
C–H···π contacts in the range of 2.7–2.9 Å (Table 3), these are
mostly relevant in 3b.
scheme. The thermal displacement ellipsoids of the non-hydrogen
atoms are drawn at the 50% probability level.
Since the complete substitution of all chloro atoms from the
silane was not achieved with N-methylaniline, a stronger nu-
cleophile was necessary. The lithium compound, lithium N-
methylanilide, was used as reagent in order to replace the re-
maining chlorine atoms of the aminosilanes 3a, 4a, 6a, and
7a. A direct synthesis of SiCl4 and SiHCl3 with lithium N-
methylanilide was applied to form 1b and 2b, respectively.
Regarding the yields, the used molecular ratio of silane to
LiNMePh was sufficient only for the reaction with the amino-
silanes 3a, 6a, and 7a but not for 4a, SiCl4, and SiHCl3
(Table 1). The direct reaction with SiCl4 gives several deriva-
tives including the disubstituted compound 1a and the product
1b in traces. The direct reaction of SiHCl3 with the lithium
salt also results in the disubstituted derivative 2a and the prod-
uct 2b in very low yields. Surprisingly, the reaction of the
intermediate 4a, ClSi(NMePh)3, with lithium N-methylanilide
gives the desired tetrasubstituted compound, but only in trace
amounts. Hence, it is assumed that the reactivity of the chlo-
rine substituted aminosilanes is reduced. Furthermore, steric
effects impede the substitution of the last chlorine atom.
In contrast to compounds 1a–4a, 6a, and 7a, the chlorine
free aminosilanes 1b–7b are solid at room temperature. Single
crystals suitable for X-ray analysis were obtained of 2b, 3b,
In order to clarify the planar nitrogen atoms in the solid-
state structures of the aminosilanes, the effects of planarization
of the nitrogen atoms were investigated with a number of
model amines (Table 4). The geometries of the optimized
structures (B3LYP/6-31G*) and the NBO analysis show that
there was an increasing degree of planarization of the nitrogen
atom when the amine was substituted with phenyl groups and
with silicon containing substituents. The hybridization of the
nitrogen atom in NMe3 is sp3 (75.4% p) with C–N–C bond
angles of 111.6°. Substitution with one phenyl group
(NMe2Ph) leads to sp2 hybridization with a nearly planar ar-
rangement of the substituents around the nitrogen atom. There
was only a 4° difference between an ideal planar amine. A
similar effect is observed in case of substitution with silicon
containing substituents. If both types of substituents are pres-
ent, an even larger planarization occurs. In this way the model
compound Me3Si–N(Me)Ph has a sum of angles at the nitro-
gen atom of 359.4°, which corresponds to a perfect sp2 hybrid-
ization of the nitrogen atom.
The same bonding situation applies to the compounds 4a,
2b, 3b, and 6b: The nitrogen atom is bound to a silane and a
phenyl group. This substitution pattern leads to a planarization
and 6b. 3b and 6b feature C3 symmetry in solution but crys- of the nitrogen atoms.
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B. Meinel, B. Günther, A. Schwarzer, U. Böhme
ARTICLE
Table 4. Calculated geometrical parameters /° and hybridization of dif-
ferent amines.
a)
b)
c)
Σ
Δ
%p
NH3
NMe3
NMe2Ph
317.2
334.8
356
42.8
25.2
4
75.0
75.4
67.6
H3Si–NMe2
Me3Si–NMe2
354.9
354.8
5.1
5.2
69.3
69.3
Me3Si–N(Me)Ph
Me3Si–NPh2
359.4
359.8
0.6
0.2
66.7
66.7
a) Σ = Sum of angles at the nitrogen atom. b) Δ = 360° – Σ; Difference
between 360° and the sum of angles at nitrogen as expression for the
degree of planarization. c) %p = Contribution of p-orbitals to the
atomic hybrid orbitals in %p as measure for the hybridization at the
nitrogen atom (75% = sp3; 66.7% = sp2).
Si–Cl, Si–H, Si–Me, and Si–Ph bonds. The reactivity of the
amine is, in most cases, not sufficient for the substitution of
the last chlorine atom at the silicon atom. If at least three chlo-
rine atoms are replaced the nucleophilicity of even lithium N-
methylanilide is too small. The final products of substitution
can only be achieved in traces. If only two NMePh moieties
are present in the products, the yields are sufficient using the
amine (5b) or lithium N-methylanilide (6b, 7b).
The reactivity of these aminosilanes towards other reagents,
e.g. CO2, isocyanates or chlorosilanes will be the limiting ef-
fect for further experiments.
The planar coordination of the nitrogen atoms in the amino-
silanes under investigation is caused by phenyl groups and
silyl substituents.
Experimental Section
General: All preparative work and handling of the samples was car-
ried out in an argon atmosphere using dry glassware and dry solvents.
n-Pentane was freshly distilled from LiAlH4. Triethylamine and 1,2-
dimethoxyethane (DME) were refluxed over sodium/benzophenone
until the color of the solution turned violet, and freshly distilled before
use. Commercially available N-methylaniline was purified by distil-
lation over KOH pellets. Lithium-N-methylanilide was prepared from
n-butyllithium (1.6 m in n-hexane) and N-methylaniline. Melting
points are uncorrected and were recorded in capillary tubes with a
Polytherm A instrument from Wagner & Munz. The NMR spectra
were recorded with a Bruker DPX 400 with SiMe4 (TMS) as internal
standard at 25 °C with 400.13 MHz for 1H NMR, 100.62 MHz for 13
C
NMR, and 79.49 MHz for 29Si NMR spectroscopy. The signals are
noted as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet)
and dd (doublet, doublet). The SiSi coupling constants were calculated
from the shift differences of the Si satellites in the 29Si NMR spectrum.
Elemental analyses were performed with a CHN-O-RAPID analyser
(Hanau). Due to the formation of silicon carbide lower carbon content
values were measured than expected. The GC-MS spectra were ob-
tained with a 70 eV Hewlett Packard 5890 Series II / 5971 Series GC /
MS system.
Figure 2. Molecular structures of the compounds 2b, 3b, and 6b in-
cluding numbering scheme. The thermal displacement ellipsoids of the
non-hydrogen atoms are drawn at the 50% probability level.
Conclusions
General Procedure for Amination of Chloroorganosilanes with N-
Methylaniline: An excess of triethylamine was added to the appropri-
ate chlorosilane solved in n-pentane. N-methylaniline also solved in n-
A number of crystalline aminosilanes derived from N-meth-
ylaniline were prepared and characterized. These compounds
bear different functionalities at the silicon atom, namely pentane was added dropwise to the reaction mixture. A voluminous
4
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Crystalline Aminoorganosilanes
white precipitate of triethylammonium chloride was formed. The sus-
pension was stirred at room temperature and refluxed for several hours.
The solvent and the excess of triethylamine were distilled off at re-
mol, 24.3 mL) and N-methylaniline (18.81g, 0.175 mol, 19 mL). After
filtration and removal of the solvent by distillation the product was
purified using high vacuum (Kp: 127 °C; 3.6ϫ10–2 Torr) to give a
duced pressure. The remaining solid was extracted with pentane and clear light-yellow oil. Yield 6.55 g (48%). 1H NMR (400MHz,
filtered several times. The solvent was partially removed from the fil-
trate in vacuo and the concentrated solution was left for several days
at 5 °C. The product was purified by filtration or distillation. Experi-
mental details are given below.
CDCl3): δ = 0.41 (s, 6 H); 2.88 (s, 6 H, NMe); 6.77–7.18 ppm (m, 10
H, Ph). 13C NMR (100 MHz, CDCl3): δ = 34.5 (NMe); 117.8, 118.9,
128.6, 149.8 ppm (Ph). 29Si NMR (79 MHz, CDCl3): δ = –0.4 ppm.
IR (KBr): ν˜ = 3021 (νC–H, aryl); 2953, 2888 (νC–H, alkyl); 2812
(νN–CH3); 1492 (δasC–H, alkyl); 1272 cm–1 (δsC–H, alkyl). GC/MS:
270 [M+, 42], 164 (SiMe2NMePh,100), 59 (SiMe2, 50).
Synthesis
of
Bis(N-Methyl-N-Phenyl-amino)dichlorosilane,
Cl2Si(NMePh)2 (1a): Compound 1a was prepared from SiCl4
(16.99 g, 0.1 mol, 11.5 mL) in n-pentane (150 mL), NEt3 (50.60 g, 0.5
mol, 69.7 mL) and N-methylaniline (53.58 g, 0.5 mol, 54.4 mL) in n-
pentane (50 mL) by stirring for 6 h at room temperature and 4 h at
reflux temperature. The oily residue from the workup procedure was
distilled at 4ϫ10–2 Torr at 122 to 126 °C to give 23.17 g (74% yield)
of a white waxy solid. 1H NMR (400 MHz, CDCl3): δ = 2.99 (s, 9 H,
NMe); 6.98–7.20 ppm (m, 15 H, Ph). 13C NMR (100 MHz, CDCl3):
δ = 37.2 (NMe); 122.9, 123.2, 128.8, 146.9 (Ph). 29Si NMR (79 MHz,
CDCl3): δ = –33.3 ppm. C14H16Cl2N2Si (311.288): calcd. C 54.0, H
5.2, N 9.0%; found C 53.57, H 4.85, N 8.99%.
Synthesis of Chloro-(N-methyl-N-phenyl-amino)diphenylsilane,
ClSi(Ph)2(NMePh) (6a): Compound 6a was prepared from Ph2SiCl2
(12.66 g, 0.05 mol, 10.5 mL) in n-pentane (80 mL), NEt3 (12.65 g,
0.125 mol, 17.3 mL) and N-methylaniline (3.39 g, 0.125 mol,
13.5 mL). After filtration and removal of the solvent by distillation the
product was purified using high vacuum (Kp: 165 °C, 2.7ϫ10–2 Torr)
to give a colorless highly viscous oil, which crystallizes below 25 °C.
Yield 8 g (49%). 1H NMR (400 MHz, CDCl3): δ = 2.98 (s, 3 H,
NMe); 7.29–7.66 (m, 10 H, Ph); 6.83–7.10 ppm (m, 5 H). 13C NMR
(100 MHz, CDCl3): δ = 37.2 (NMe); 128.4, 130.6, 132.9, 134.8 (SiPh);
121.2; 121.3; 128.4; 148.4 ppm (NPh). 29Si NMR (79 MHz, CDCl3):
δ = –8.0 ppm. GC/MS: 323 [M+, 79], 217 (ClSiPh2, 100), 219
(ClSiPh2, 32), 182 (SiPh2, 5). C19H18ClNSi (323.89): calcd. C 70.46,
H 5.60 N 4.32%; found C 70.46, H 5.60, N 4.33%.
Synthesis
of
Bis(N-methyl-N-phenyl-amino)chlorosilane,
Cl(H)Si(NMePh)2 (2a): Compound 2a was prepared from HSiCl3
(13.41 g, 0.099 mol, 10 mL) in n-pentane (150 mL), NEt3 (30.06 g
0.297 mol, 41.4 mL) and N-methylaniline (21.22 g, 0.198 mol,
21.5 mL) in n-pentane (50 mL) by stirring for 9 h at room temperature
and 2 h at reflux temperature. White solid from n-pentane. M.p.
215 °C. Yield 13.1 g (48%). 1H NMR (400MHz, CDCl3): δ = 2.99 (s,
6 H, NMe); 5.60 (s, 1 H, SiH); 6.93–7.28 ppm (m, 10 H, Ph). 13C
NMR (100 MHz, CDCl3): δ = 32.1 (NMe); 115.8, 119.5, 129.2,
148.2 ppm (Ph). 29Si NMR (79 MHz, CDCl3): δ = –28.8 ppm.
C14H17ClN2Si (276.84): calcd. C 60.74, H 6.19, N 10.12%; found C
60.13, H 6.60, N 9.08%.
Synthesis of Chloro-(N-methyl-N-phenyl-amino)methyl-phenyl-
silane, ClSiMePh(NMePh) (7a): Compound 7a was prepared from
MePhSiCl2 (5.73 g, 0.03 mol, 4.9 mL) in n-pentane (50 mL), NEt3
(7.59 g, 0.075 mol, 10.4 mL), and N-methylaniline (8.04 g, 0.075 mol,
8.1 mL). After filtration and removal of the solvent by distillation the
product was purified using high vacuum (Kp: 103 °C; 4ϫ10–3 Torr)
to give a clear light-yellow oil. Yield 3.8 g (48%). 1H NMR (400MHz,
CDCl3): δ = 0.68 (s, 3 H); 2.94 (s, 3 H, NMe); 7.37–7.71 (m, 5 H,
Ph); 6.94–7.71 ppm (m, 5 H). 13C NMR (100 MHz, CDCl3): δ = 2.6
(SiMe); 37.0 (NMe); 122.2, 128.1, 130.4, 133.9 (SiPh); 122.0; 122.3;
128.7; 148.7 ppm (NPh). 29Si NMR (79 MHz, CDCl3): δ = 2.5 ppm.
IR (KBr): ν˜ = 3071, 3054 (νC–H, aryl); 2935, 2903 (νC–H, alkyl);
2818 (νN–CH3); 1429 (δasC–H, alkyl); 1269 (δsC–H, alkyl); 1116
(νSi–C, aryl); 889 cm–1 (νC–H, alkyl). GC/MS: 261 (M, 100), 155
(SiMePhCl, 77), 157 (SiMePhCl, 27).
Synthesis of Bis(N-methyl-N-phenyl-amino)chloromethylsilane
ClSiMe(NMePh)2 (3a): Compound 3a was prepared from MeSiCl3
(7.47 g, 0.05 mol, 5.8 mL) in n-pentane (100 mL) and NEt3 (20.24 g,
0.2 mol, 27.7 mL) and N-methylaniline (21.43 g, 0.2 mol, 21.6 mL)
in n-pentane (50 mL). After filtration and removal of the solvent by
distillation the product was purified using high vacuum (Kp: 103 °C;
2.5ϫ10–2 Torr). Yield 6 g (41%), clear colorless oil. 1H NMR
(400MHz, CDCl3): δ = 0.63 (s, 3 H); 2.96 (s, 6 H, NMe); 6.89–
7.23 ppm (m, 10 H, Ph). 13C NMR (100 MHz, CDCl3): δ = 2.1
(SiMe); 35.8 (NMe); 120.6, 121.4, 128.7, 148.2 ppm (Ph). 29Si NMR
(79 MHz, CDCl3): δ = –10.0 ppm. Chlorine content: calcd. 12.07%,
found 13.04%
General Procedure for Amination of Chloroorganosilanes with
Lithium-N-methylanilid: Lithium N-methylanilid as well as chloro-
organosilane were dissolved in DME in two separate Schlenk flasks
and cooled to –78 °C. The solution of the chloroorganosilane was
added to the lithium N-methylanilid via a glass joint and stirred for 10
min at –78 °C. Subsequent, the mixture was slowly warmed to room
temperature; thereby the solution became clear and orange. After stir-
ring the mixture for a prolonged time at room temperature and at reflux
temperature a precipitate was formed. The solvent was removed in
vacuo and the oily residue was extracted with n-pentane. The resulting
mixture was filtered and the volume of the filtrate was reduced step-
wise by distillation at reduced pressure. The solution was left for sev-
eral days at 5 °C. The product crystallized or precipitated from the
concentrated solution and was isolated by filtration. Experimental de-
tails are given below.
Synthesis of Bis(N-methyl-N-phenyl-amino)chloro-phenylsilane,
ClSiPh(NMePh)2 (4a): Compound 4a was prepared from PhSiCl3
(12.69 g, 0.06 mol, 9.6 mL) in n-pentane (100 mL), NEt3 (25.30 g,
0.25 mol, 34.6 mL) and N-methylaniline (21.43 g, 0.2 mol, 21.6 mL).
After filtration and removal of the solvent by distillation the product
was purified by crystallization from n-pentane as colorless crystals.
Yield 4 g (19%). M.p.: 68.1 °C. 1H NMR (400MHz, CDCl3): δ = 2.99
(s, 6 H, NMe); 7.35–7.46 (m, 5 H, Ph); 6.89–7.23 ppm (m, 10 H). 13
C
NMR (100 MHz, CDCl3): δ = 36.1 (NMe); 120.4, 128.2, 130.9, 135.0
(SiPh); 120.4; 121.2; 128.5; 148.0 ppm (NPh). 29Si NMR (79 MHz,
CDCl3): δ = –21.2 ppm. C20H21Cl1N2Si (352.938): calcd. C 68.06, H
6.0, N 7.94; found C 68.45, H 6.17, N 7.96%.
Synthesis of Tetra-(N-methyl-N-phenyl-amino)silane, Si(NMePh)4
(1b): Compound 1b was prepared from SiCl4 (2.48 g, 14.6 mmol,
1.7 mL), lithium N-methylanilid (6.78 g, 0.06 mol) and ca. 400 mL
Synthesis of Bis(N-methyl-N-phenyl-amino)dimethylsilane, Si- DME by stirring for 165 h at room temperature and 2 h at reflux
Me2(NMePh)2 (5b): Compound 5b was prepared from Me2SiCl2 temperature. The amount of raw product is very low and was only
(6.45 g, 0.05 mol, 6 mL) in n-pentane (50 mL), NEt3 (17.71 g, 0.175
sufficient for NMR spectroscopic analyses. 29Si NMR spectrum indi-
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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B. Meinel, B. Günther, A. Schwarzer, U. Böhme
ARTICLE
cates the formation of several derivatives including 1a and 1b. 29Si (NMe); 112.4, 118.1, 119.2, 128.3, 128.7, 129.2, 129.9, 134.6,
NMR (79 MHz, CDCl3): δ = –35.8, 46.9 48.2, 50.6, 57.1, 57.6 ppm.
149.8 ppm (Ph). 29Si NMR (79 MHz, CDCl3):
δ = –8.8 ppm.
C21H24N2Si (332.520): calcd. C 75.85, H 7.28, N 8.42%; found C
75.76, H 7.46, N 8.89%.
Synthesis of Tri-(N-methyl-N-phenyl-amino)silane, HSi(NMePh)3
(2b): Compound 2b was prepared from HSiCl3 (9.48 g, 0.07 mol,
7 mL), lithium N-methylanilid (25.02 g, 0.22 mol) and ca. 400 mL
DME by stirring for 134 h at room temperature and 2 h at reflux
temperature. The first fraction of isolated product contains 3.6 g (15%
yield) Cl(H)Si(NMePh)2 (2a). Further fractions were mixtures of 2a
and 2b, no yield was determined from these fractions. The last fraction
were 1.4 g (6% yield) of 2b, which contained still traces of 2a.
Recrystallization from ethyl ether and n-pentane yielded white crystals
of 2b suitable for X-ray structure analysis. 1H NMR (400MHz,
CDCl3): δ = 2.93 (s, 9 H, NMe); 5.35 (s, 1 H, SiH); 6.61–7.29 ppm
(m, 15 H, Ph).). 13C NMR (100 MHz, CDCl3): δ = 32.1 (NMe); 115.8,
119.5, 129.2, 148.2 ppm (Ph). 29Si NMR (79 MHz, CDCl3): δ =
–33.8 ppm.
Crystal Structure Determination: Single crystals suitable for single
X-ray diffraction experiments of compounds 4a, 2b, 3b, and 6b were
grown from pentane solution at 8 °C. The structures of 4a and 2b were
determined with an Enraf–Nonius CAD4 diffractometer using graphite
monochromated Cu-Kα radiation (λ = 1.5418 Å). The X-ray single
crystal structure analyses of 3b and 6b were performed with a
BRUKER NONIUS X8 APEX2 CCD diffractometer using graphite
monochromated Mo-Kα radiation (λ = 0.71073 Å). The structures were
solved by direct methods.[22] The non-hydrogen atoms were refined
anisotropically.[23] A riding model was used for the hydrogen atoms.
¯
Crystal Data for 4a: C20H21ClN2Si, M = 352.93, triclinic, P1, a =
8.3240(10) Å, b = 9.286(2) Å, c = 12.825(2) Å, α = 69.41(2)°, β =
88.81(2)°, γ = 83.84(2)°, V = 922.5(3) Å3, Dc = 1.271 Mg·m–3, T =
293(2) K, Z = 2, μ(Cu-Kα) = 2.465 mm–1, 5842 reflections measured,
3801 independent reflections (Rint = 0.0277), 219 parameters. The final
R1 values were 0.0525 [I Ͼ 2σ(I)]. The final wR(F2) values were
0.1362 [I Ͼ 2σ(I)]. The final R1 values were 0.0603 (all data). The
final wR(F2) values were 0.1431 (all data). The goodness of fit on F2
was 1.117.
Synthesis
of
Tri-(N-methyl-N-phenyl-amino)methylsilane,
MeSi(NMePh)3 (3b): Compound 3b was prepared from 3a (5.44 g,
0.019 mol), lithium N-methylanilid (2.43 g, 0.021 mol) and ca. 200 mL
DME by stirring for 110 h at room temperature and 2 h at reflux
temperature to give a light brown solid. Yield: 4.33 g (63%). M.p.
128 °C. 1H NMR (400MHz, CDCl3): δ = 0.52 (s, 3 H, SiMe); 2.99 (s,
9 H, NMe); 6.85–7.27 ppm (m, 15 H, Ph). 13C NMR (100 MHz,
CDCl3): δ = –1.9 (SiMe); 33.7 (NMe); 117.4, 119.3, 129.0, 148.7 ppm
(Ph). 29Si NMR (79 MHz, CDCl3): δ = –17.2 ppm. C22H27N3Si
(361.56): calcd. C 73.08, H 7.53, N 11.62%; found C 72.88, H 7.32,
N 11.07%.
Crystal Data for 2b: C21H25N3Si, M = 347.53, trigonal, R3, a =
12.937(2) Å, b = 12.937(2) Å, c = 9.8420(10) Å, α = 90.00°, β =
90.00°, γ = 120.00°, V = 1426.5(3) Å3, Dc = 1.214 Mg·m–3, T = 193(2)
K, Z = 3, μ(Cu-Kα) = 1.135mm–1, 3447 reflections measured, 1316
independent reflections (Rint = 0.0451), 79 parameters. The final R1
values were 0.0379 [I Ͼ 2σ(I)]. The final wR(F2) values were 0.0949
[I Ͼ 2σ(I)]. The final R1 values were 0.0391 (all data). The final
wR(F2) values were 0.0962 (all data). The goodness of fit on F2 was
1.114. Flack parameter = 0.05(3).
Synthesis
of
Tri-(N-methyl-N-phenyl-amino)phenylsilane,
PhSi(NMePh)3 (4b): Compound 4b was prepared from 4a (2.00 g,
5.8 mmol), lithium N-methylanilid (0.72 g, 6.4 mmol) and ca. 130 mL
DME by stirring for 160 h at room temperature and 2 h at reflux
temperature to give a white solid in low yields. 29Si NMR spectrum
indicates the presence of several derivatives including 4a and 4b.
Crystallization from n-hexane resulted in 4b in traces being only suf-
Crystal Data for 3b: C22H27N3Si, M = 361.56, monoclinic, P21/n,
a = 9.8595(3) Å, b = 18.3930(5) Å, c = 10.9533(3) Å, α = 90.00°, β =
97.6000(10)°, γ = 90.00°, V = 1968.89(10) Å3, Dc = 1.220 Mg·m–3,
T = 93(2) K, Z = 4, μ(Mo-Kα) = 0.130 mm–1, 30023 reflections mea-
sured, 5231 independent reflections (Rint = 0.0267), 239 parameters.
The final R1 values were 0.0369 [I Ͼ 2σ(I)]. The final wR(F2) values
were 0.1027 [I Ͼ 2σ(I)]. The final R1 values were 0.0448 (all data).
The final wR(F2) values were 0.1071 (all data). The goodness of fit
on F2 was 1.072.
1
ficient for NMR spectroscopic analyses. H NMR (400MHz, CDCl3):
δ = 2.85 (NMe); 6.70–7.27 ppm (Ph). 13C NMR (100 MHz, CDCl3):
δ = 31.5 (NMe); 113.4, 118.2, 118.3, 126.2, 128.9 129.7, 135.7
149.3 ppm (NPh, SiPh). 29Si NMR (79 MHz, CDCl3): δ = –43.8 ppm.
Synthesis
of
Bis(N-methyl-N-phenyl-amino)diphenylsilane,
Ph2Si(NMePh)2 (6b): Compound 6b was prepared from 6a (4.77 g,
0.015 mol), lithium N-methylanilid (2.0 g, 0.0177 mol) and ca. 200 mL
DME by stirring for 116 h at room temperature and 2 h at reflux
temperature to give a light brown solid. Yield: 3.3 g (56%). M.p.
1
Crystal Data for 6b: C26H26N2Si, M = 394.58, monoclinic, C2/c,
a = 17.925(4) Å, b = 10.761(2) Å, c = 22.516(5) Å, α = 90.00°, β =
92.01(3)°, γ = 90.00°, V = 4340.6(15) Å3, Dc = 1.208 Mg·m–3, T =
203(2) K, Z = 8, μ(Mo-Kα) = 0.122 mm–1, 14852 reflections measured,
4979 independent reflections (Rint = 0.0288), 264 parameters. The final
R1 values were 0.0391 [I Ͼ 2σ(I)]. The final wR(F2) values were
0.0976 [I Ͼ 2σ(I)]. The final R1 values were 0.0581 (all data). The
final wR(F2) values were 0.1037 (all data). The goodness of fit on F2
102 °C. H NMR (400MHz, CDCl3): δ = 3.06 (s, 6 H, NMe); 6.74–
7.59 ppm (m, 20 H, Ph). 13C NMR (100 MHz, CDCl3): δ = 36.3
(NMe); 119.2, 119.5, 127.8, 128.4, 129.7, 134.1, 135.9, 149.7 ppm
(Ph). 29Si NMR (79 MHz, CDCl3): δ = –19.9 ppm. C26H26N2Si
(394.58): calcd. C 79.14, H 6.64, N 7.10%; found C 78.17, H 6.85, N
7.12%.
Synthesis of Bis(N-methyl-N-phenyl-amino)methyl-phenylsilane,
Ph(Me)Si(NMePh)2 (7b): Compound 7b was prepared from 7a (2.1 g, was 1.069.
0.008 mol), lithium N-methylanilid (2.08 g, 0.018 mol), and ca.
100 mL DME. A large excess of lithium N-methylanilid was necessary
Crystallographic data (excluding structure factors) for the structures in
in this case in order to obtain the desired product. Reaction with molar this paper have been deposited with the Cambridge Crystallographic
ratio 1: 1.1 gave a product mixture. Stirring for 90 h at room tempera-
ture and 2 h at reflux temperature resulted in a light red solid product.
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
Yield: 1.57 g (59% based on 5). M.p. 68 °C. 1H NMR (400MHz, numbers CCDC-160251 (4a), CCDC-182213 (2b), CCDC-976505
CDCl3): δ = 0.63 (s, 3 H, SiMe); 2.94 (s, 6 H, NMe), 6.83–7.60 ppm
(m, 15 H, Ph). 13C NMR (100 MHz, CDCl3): δ = –1.4 (SiMe); 35.6
(3b), and CCDC-228310 (6b) (Fax: +44-1223-336-033; E-Mail:
deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk)
6
www.zaac.wiley-vch.de
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Crystalline Aminoorganosilanes
[11] C. Ackerhans, B. Räke, R. Krätzner, P. Müller, H. W. Roesky, I.
Usòn, Eur. J. Inorg. Chem. 2000, 827–830.
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[12] J. Heinicke, S. Mantey, A. Oprea, M. K. Kindermann, P. G. Jones,
Heteroat. Chem. 1999, 10, 605–614.
[13] I. Rietz, E. Popowski, H. Reinke, M. Michalik, J. Organomet.
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A.S. thanks the TU Bergakademie Freiberg for the Postdoctoral Re-
search Fellowship “Mary Hegeler”.
[14] Th. Schlosser, A. Sladek, W. Hiller, H. Schmidbaur, Z. Natur-
forsch. B 1994, 49, 1247–1255.
[15] K. Kraushaar, C. Wiltzsch, J. Wagler, U. Böhme, A. Schwarzer,
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[16] C. Wiltzsch, K. Kraushaar, A. Schwarzer, E. Kroke, Z. Natur-
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[17] U. Böhme, B. Günther, B. Rittmeister, Eur. J. Inorg. Chem. 2003,
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[18] U. Böhme, B. Günther, B. Rittmeister, Inorg. Chem. Commun.
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[19] Supramolecular Assembly via Hydrogen Bonds I and II, Structure
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Received: December 13, 2013
Published Online: ᭿
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© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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ARTICLE
B. Meinel, B. Günther, A. Schwarzer, U. Böhme* ........... 1–8
Crystalline Aminoorganosilanes – Syntheses, Structures, Spec-
troscopic Properties
8
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