Syntheses and structures of (N′,N′-dimethylhydrazido)silanes

Article abstract of DOI:10.1039/b900293f

The hydrazidosilanes Ph₂Si(NHNMe₂)₂ (1), Me₂Si(NHNMe₂)₂ (2), PhSi(NHNMe ₂)₃ (3), MeSi(NHNMe₂)₃ (4), PhClSi(NHNMe₂)₂ (5), Me

Full text of DOI:10.1039/b900293f

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PAPER
www.rsc.org/dalton | Dalton Transactions
Syntheses and structures of (N¢,N¢-dimethylhydrazido)silanes†
Ingo Gronde,a Beate Neumann,a Alexander Willner,a Tania Papeb and Norbert W. Mitzel*a
Received 7th January 2009, Accepted 16th April 2009
First published as an Advance Article on the web 15th May 2009
DOI: 10.1039/b900293f
The hydrazidosilanes Ph2Si(NHNMe2)2 (1), Me2Si(NHNMe2)2 (2), PhSi(NHNMe2)3 (3),
MeSi(NHNMe2)3 (4), PhClSi(NHNMe2)2 (5), MeClSi(NHNMe2)2 (6), Me2ClSi(NHNMe2) (7),
MeClHSi(NHNMe2) (8), MeHSi(NHNMe2)2 (9), Me2HSi(NHNMe2) (10), Me2NN[HSi(NHNMe2)2]2
(11) and Si(NHNMe2)4 (12) have been prepared by the reaction of the corresponding chlorosilanes with
N,N -dimethylhydrazine. Some of the compounds containing Si–Cl and N–H functions simultaneously
(6, 7, 8) are very reactive and tend to polymerise and could only be characterised by spectroscopic
methods (1H, 13C, 29Si NMR, IR, MS). All other compounds could additionally be characterised by
elemental analyses. The structures of 1, 2, 5, 9, 11 and 12 in the solid state were determined by X-ray
diffraction. These include the first structural determinations of compounds containing SiH–NH–N (9,
11) and SiCl–NH–N (5) units.
In order to reduce the carbon content, the introduction of
Introduction
hydrazide substituents with NH functions is desirable. From a
thermodynamic view, SiH and NH functions near each other
in one molecule are not stable,8 but there are quite a few stable
representatives of such compounds; 1,1,2,2-tetramethyldisilazane9
for instance is commercially available.
Here we present a range of different hydrazidosilanes and show
the limits of their stability with regard to the presence of mutually
reacting groups and their intermolecular aggregation motifs.
Hydrazidosilanes are potentially useful single source precursors
for the chemical vapour deposition (CVD) of silicon nitride1
and metal silicon nitride.2 Silicon nitride is an important thin
passivation layer and dielectric in the fabrication of semiconductor
devices. The trend towards further down-scaling of these devices
requires lower process temperatures. Hydrazides of silicon could
have some potential in this context, due to the presence of
weak N–N bonds, which can serve as predetermined breaking
points. Therefore, hydrazidosilanes with high vapour pressure,
zero chlorine content, low carbon but high nitrogen content are
desirable synthetic targets.
Results and discussion
Diorganyl-dihydrazidosilanes
Two main methods of preparation of hydrazidosilanes are
known: the reaction of a hydrazine with a halosilane in the
presence of an auxiliary base (triethylamine, hydrazine etc.) and
the reaction of a halosilane with a lithiated hydrazine under
elimination of lithium halide.3 The resulting hydrazidosilanes
are sensitive towards moisture, which transforms them into
disiloxanes.
Here we distinguish between silylhydrazines (one or many silyl
groups bonded to a hydrazine unit) and hydrazidosilanes (many
hydrazine units bonded to a silicon atom). Whereas a large
number of silylhydrazines have been prepared,4 the chemistry of
hydrazidosilanes5 is much less developed. The syntheses of the first
hydrazidosilanes were reported by Wannagat6 and Tsitovich7 in
the early 1960s. Most of these compounds contain organic groups
bound to the nitrogen and silicon atoms, which protect the sensitive
hydrazine unit.
Ph2Si(NHNMe2)2 (1) and Me2Si(NHNMe2)2 (2). The com-
pounds Ph2Si(NHNMe2)2 (1), and Me2Si(NHNMe2)2 (2) were
synthesised previously,7,10 but their crystal structures remained
so far unknown. We obtained these compounds by the reaction
of dichlorophenylsilane or dichlorodimethylsilane with a fourfold
excess of unsymmetrical N,N -dimethylhydrazine (UDMH) in
hexane after refluxing the reaction mixture for several hours to
ensure complete substitution of all chlorine atoms.
R2SiCl2 + 4 H2NNMe2 →
R2Si(NHNMe2)2 + 2 [H3NNMe2]Cl
R = Ph (1), Me (2)
After filtration of the precipitated salt and distillation, the
bis(N¢,N¢-dimethylhydrazido)silanes crystallise from hexane so-
lutions at -25 ◦C and were characterised by NMR (1H, 13C, 29Si)
and IR spectroscopy (see Table 1), by mass spectrometry and
single crystal X-ray diffraction. Fig. 1 displays the solid-state struc-
ture of bis(N¢,N¢-dimethylhydrazido)diphenylsilane 1 and Fig. 2
the structure of bis(N¢,N¢-dimethylhydrazido)dimethylsilane 2.
Tables 2 and 3 contain selected structural parameter values.
aUniversita¨t Bielefeld, Fakulta¨t fu¨r Chemie, Anorganische Chemie und
Strukturchemie, Universita¨tsstraße 25, 33615, Bielefeld, Germany. E-mail:
mitzel@uni-bielefeld.de; Fax: +49 (0)521 106-6026; Tel: +49 (0) 521 106-
6163
bUniversita¨t Mu¨nster, Institut fu¨r Anorganische und Analytische Chemie,
Corrensstraße 30, 48149, Mu¨nster, Germany
† CCDC reference numbers are 715611, 715612, 715613, 715614, 715615
and 715616 for 1, 2, 5, 9, 11 and 12, respectively. For crystallographic data
in CIF or other electronic format see DOI: 10.1039/b900293f
¯
Both compounds crystallise in the triclinic space group P1
with two molecules in the unit cell. The Si–N, Si–C and
5300 | Dalton Trans., 2009, 5300–5309
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Table 1 Selected spectroscopic parameter values of compounds 1–11. NMR chemical shifts are given in ppm relative to TMS, IR frequencies are given
in cm-1
Compound
No.
d(29Si)
d(1H) HN
d(1H) Me2N
d(1H) HSi
d(13C) Me2N
n(NH)
n(SiH)
Ph2Si(NHNMe2)2
Me2Si(NHNMe2)2
PhSi(NHNMe2)3
1
-38.6
-12.7
-22.2
-28.9
1.7
-6.8
8.5
-19.5
-28.4
-14.7
-45.8
-45.9
2.34
2.04
2.00
2.08
2.37
2.39
2.36
2.42
2.22
1.81
2.18
2.16
2.40
2.25
2.43
2.29
2.23
2.28
2.45
2.69
2.36
2.22
2.33
2.34
—
—
—
—
—
—
—
5.17
4.78
4.67
4.79
—
52.4
52.4
51.6
52.7
52.6
51.8
51.8
48.1
51.8
51.7
52.4
52.7
3278
3278
3293
3275
3284
3268
3284
3300
3278
3285
3275
3200
—
—
—
—
—
—
—
2218
2131
2135
2146
—
2
3
MeSi(NHNMe2)3
PhClSi(NHNMe2)2
MeClSi(NHNMe2)2
Me2ClSi(NHNMe2)
MeClHSi(NHNMe2)
MeHSi(NHNMe2)2
Me2HSi(NHNMe2)
Me2NN[SiH(NHNMe2)]2
Si(NHNMe2)4
4
5
6
7
8
9
10
11
12
˚
Table 2 Selected structural parameters (A, deg) of Ph2Si(NHNMe2)2 (1)
Si–N(1)
Si–N(3)
N(1)–N(2)
N(3)–N(4)
Si–C(5)
1.703(2)
1.704(3)
1.426(3)
1.418(3)
1.866(3)
1.874(3)
C(5)–Si–C(11)
N(1)–Si–N(3)
N(1)–Si–C(5)
N(3)–Si–C(11)
N(1)–Si–C(11)
N(4)–N(3)–Si
N(2)–N(1)–Si
111.4 (1)
112.5 (1)
113.9 (1)
113.3 (1)
104.0 (1)
123.0 (2)
120.6 (2)
Si–C(11)
˚
Table 3 Selected structural parameters (A, deg) of Me2Si(NHNMe2)2 (2)
Si–N(1)
Si–N(3)
Si–C(1)
Si–C(2)
N(1)–N(2)
N(3)–N(4)
1.703(4)
1.704(4)
1.853(4)
1.841(4)
1.425(4)
1.420(4)
C(1)–Si–C(2)
N(1)–Si–N(3)
N(1)–Si–C(1)
N(1)–Si–C(2)
N(2)–N(1)–Si
N(4)–N(3)–Si
113.1(2)
117.2(2)
109.4(2)
104.1(2)
121.3(3)
120.3(3)
Fig. 1 Crystal structure of 1. Ellipsoids are drawn at the 50% level,
hydrogen atoms except those bound to N are omitted for clarity.
Fig. 3 Aggregation of 2 in the crystal showing the weak hydrogen
bonding. Hydrogen atoms except those bound to N are omitted for clarity.
Symmetry operations for generating neighbour molecules, A: -x + 1,
-y + 1, -z + 1; B: -x + 1, -y + 2,-z + 1.
Fig. 2 Crystal structure of 2. Ellipsoids are drawn at the 50% level,
hydrogen atoms except those bound to N are omitted for clarity.
N–N bond lengths are all similar to those observed in other
representative silylhydrazines.2 While there is no intermolecular
hydrogen bonding between the molecules with N ◊ ◊ ◊ H contacts
2 the N–N–Si angles are close to 120◦. This indicates the absence
of b-donor Si ◊ ◊ ◊ N interactions, which are frequently observed for
isoelectronic hydoxylaminosilanes.12
˚
closer than 3 A in 1, compound 2 shows such N ◊ ◊ ◊ H contacts of
˚
˚
2.64(4) A and 2.67(3) A lengths between neighbouring molecules
as depicted in Fig. 3. According to the classification by Desiraju
and Steiner,11 these hydrogen bonds have to be specified as weak.
Although geminal intramolecular interactions between the
silicon and nitrogen atoms in hydrazidosilanes, resulting in smaller
Si–N–N angles, are known,4o,p,5 in the case of compounds 1 and
The Si–N bonds in 1 and 2 are all of identical length within
˚
one standard deviation (average 1.704 A). They are well within
the established range for such lengths. The N–N bonds in 1 and
2 are relatively short as found for hydrazines, that bear only
one silicon substituent (compare H3Si(Me)NNMe2: 1.432(2) and
4o
˚
(H3Si)2NNMe2: 1.461(3) A).
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˚
Organyl-trihydrazido-silanes PhSi(NHNMe2)3 (3) and
MeSi(NHNMe2)3 (4)
Table 4 Selected structural parameters (A, deg) of PhClSi(NHNMe2)2
(5)
Si–N(1)
Si–N(3)
Si–Cl(1)
Si–C(5)
N1–N(2)
N3–N(4)
1.691(3)
1.697(3)
2.099(1)
1.851(3)
1.422(4)
1.434(3)
C(5)–Si–C(11)
N(1)–Si–N(3)
N(1)–Si–C(5)
N(1)–Si–Cl(1)
N(2)–N(1)–Si
N(4)–N(3)–Si
105.6(1)
106.1(1)
108.1(1)
113.4(1)
119.4(2)
120.6(2)
Two compounds of this type were synthesised. Starting from
trichloromethylsilane and trichlorophenylsilane the reactions with
UDMH gave phenyltris(N¢,N¢-dimethylhydrazido)silane (3) and
methyltris(N¢,N¢-dimethylhydrazido)silane (4)
RSiCl3 + 6 H2NNMe2 →
RSi(NHNMe2)3 + 3 [H3NNMe2]Cl
R = Ph (3), Me (4)
Both compounds were characterised by NMR (1H, 13C, 29Si) and
IR spectroscopy, by mass spectrometry and elemental analyses.
Despite various attempts, it was not possible to grow single crystals
suitable for X-ray diffraction experiments.
The 29Si NMR signals of the monoorganyl-trihydrazidosilanes
3 and 4 (-22.2 and -28.9 ppm) are low-field shifted with respect to
the di-organyl-dihydrazidosilanes 1 and 2 (-38.6 and -12.7 ppm),
whereas the other corresponding NMR parameters are quite
similar (see Table 1).
Organyl-hydrazido-chlorosilanes
Ph(Cl)Si(NHNMe2)2 (5). We were able to isolate a partially
hydrazido-substituted, while still retaining the Si–Cl function,
Fig. 4 Crystal structure of 5. Ellipsoids are drawn at the 50% level,
hydrogen atoms except those bound to N are omitted for clarity.
compound
bis(N¢,N¢-dimethylhydrazido)chlorophenylsilane,
Ph(Cl)Si(NHNMe2)2 (3), from the reaction of trichlorophenylsi-
lane and UDMH.
14
˚
and 2.043(1) A) and longer than in standard Si/Cl compounds
15
˚
˚
like SiCl4 (2.019(3) A) or Me2SiCl2 (2.055(2) A).
˚
˚
The bonds Si(1)–N(1) (1.692(3) A) and Si–N(3) (1.697(3) A)
are at the short range end of Si–N bonds in such systems, due
PhSiCl3 + 4 H2NNMe2 →
to the electronegative Cl substituent. This range can be defined
Ph(Cl)Si(NHNMe2)2 (5) + 2 [H3NNMe2]Cl
16
˚
by Cl3SiNMe2 (1.657(12) A in the gas phase) and (Cl3Si)3N
17
The identity of 5 was proven by NMR spectroscopy (1H,
13C, 29Si), IR spectroscopy and mass spectrometry. The 29Si
NMR signal (1.7 ppm) shows a clear low-field shift compared
to compounds 1 and 2 (-38.6 and -13.6 ppm) and also with
respect to 3, showing the different electronic influence of chloro
and hydrazido substituents in an otherwise identical substitution
pattern at the silicon atom. The other corresponding NMR
parameters are quite similar and do not deserve more detailed
comments (see Table 1).
Compounds containing SiCl–NH units are normally considered
to easily undergo polymerisation reactions or condensation with
HCl elimination often under formation of six-membered rings.
For this reason only fluoro-substituted hydrazidosilanes with
simultaneous presence of Si–F and Si–H functions were obtained
so far, because the strength of the Si–F bond prevents the
formation of HF kinetically.13
(1.763(3) A, solid). The Si–N bonds in 1 and 2 with no chlorine
˚
substituent at silicon are much longer.
A set of weak hydrogen bonds of the N–H ◊ ◊ ◊ N and the
N–H ◊ ◊ ◊ Cl type can be identified as a motif for chain formation in
the crystal structure of 5 (see Fig. 5).
Compound 5 contains relatively short N–N bonds with lengths
˚
of 1.422(4) and 1.434(3) A, which are even shorter than those
in 1 and 2. This is obviously due to the electronegative chloro
substituent. The silicon-bound atoms N(1) and N(3) show a planar
coordination sphere. Wide N–N–Si angles at these atoms of about
120◦ indicate the absence of b-donor N ◊ ◊ ◊ Si interactions.
MeClSi(NHNMe2)2 (6) and Me2ClSi(NHNMe2) (7). The par-
tially substituted hydrazidosilanes MeClSi(NHNMe2)2 (6) and
Me2ClSi(NHNMe2) (7) were obtained by carefully adding UDMH
to cold solutions of Me2SiCl2 and MeSiCl3, respectively.
Compound 5 crystallises from pentane in the orthorhombic
space group P212121 with four molecules in the unit cell and
thus we were able to determine the first solid state structure of a
simultaneously Si–Cl and N–H functional hydrazidosilane. Fig. 4
shows the structure of compound 5, structural parameter values
are listed in Table 4.
MeSiCl3 + 4 H2NNMe2 →
MeClSi(NHNMe2)2 (6) + 2 [H3NNMe2]Cl
Me2SiCl2 + 2 H2NNMe2 →
˚
The Si–Cl bond length of 5 at 2.099(1) A is quite long, i.e. longer
than that in trichloro(dimethylamino)silane (Me2NSiCl3, 2.023(1)
Me2ClSi(NHNMe2) (7) + [H3NNMe2]Cl
5302 | Dalton Trans., 2009, 5300–5309
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˚
Table 5 Selected structural parameters (A, deg) of Me(H)Si(NHNMe2)2
(9)
Si–N(1)
Si–N(3)
Si–C(1)
Si–H
N(1)–N(2)
N(3)–N(4)
1.702(2)
1.699(2)
1.696(5)
1.72(6)
1.418(3)
1.416(3)
N(2)–N(1)–Si
N(4)–N(3)–Si
C(1)–Si–N(1)
C(1)–Si–N(3)
N(1)–Si–N(3)
N(1)–Si–H
118.7(2)
120.6(2)
113.9(2)
107.1(2)
118.4(1)
107.4(2)
99.8(2)
N(3)–Si–H
Me(H)SiCl2 + 4 H2NNMe2 →
Me(H)Si(NHNMe2)2 (9) + 2 [H3NNMe2]Cl
Fig. 5 Aggregation of 5 in the crystal showing the weak hydrogen
bonding. Hydrogen atoms except those bound to N are omitted for clarity.
Compound 9 has typical NMR spectroscopic properties (see
Table 1) with deviations from the other compounds mentioned
here too small to be worth discussing in detail. It could be
crystallised from hexane and therefore its crystal structure could
be determined. Fig. 6 presents the molecular structure of 9. It
˚
˚
˚
Structural parameters ◦are: N(1)–H 0.81(4) A, N(4A) ◊ ◊ ◊ H 2.68(4) A,
˚
N(1)–H–N(4A) 160(2) , N(1)–N(4A) 3.457(3) A; N(3)–H 0.72(3) A,
◦
˚
Cl(1B) ◊ ◊ ◊ H 3.11(3) A, N(3)–H–Cl(1B) 166(3) . Symmetry operations for
generating neighbour molecules, A: -x + 1, -y + 1, -z - 1; B: -x + 2, y,
-z + 1.
¯
crystallises in the triclinic space group P1 with two molecules
in the unit cell and is the first structurally examined substance
with an SiH–NH–N unit and quite stable despite simultaneously
containing N–H and Si–H functions. As found for the molecules
Unlike 5, compounds 6 and 7 cannot be yielded as completely
pure products, as attempts to distill the raw products leads to
further condensation yielding polymeric materials and all attempts
to crystallise them failed. Thus they were characterised by their
NMR spectroscopic properties (see Table 1 and Experimental
section).
˚
above, the N–N bonds are relatively short (average 1.417 A, see
Table 5).
Organyl-hydrazido-hydridosilanes
MeClHSi(NHNMe2) (8). The reaction of dichloromethylsi-
lane, MeSiHCl2 with two equivalents UDMH resulted in the
formation of MeClHSi(NHNMe2) (8), but this compound is
difficult to separate or purify due to its instability. This is due
to possible redistribution and condensation reactions.
Me(H)SiCl2 + 2 H2NNMe2 →
Fig. 6 Molecular structure of 9 in the crystal. The carbon atom C1 and
the SiH hydrogen atom are disordered to either side of the silicon atom.
Ellipsoids are drawn at the 50% level, hydrogen atoms except those bound
to N and Si are omitted for clarity.
MeClHSi(NHNMe2) (8) + [H3NNMe2]Cl
We could therefore only obtain a raw product and iden-
tify it as a major component (> 90%) by its spectroscopic
data along with bis(N¢,N¢-dimethylhydrazino)methylsilane (9),
Me(H)Si(NHNMe2)2 and traces of other compounds. The insta-
bility of compound 8 finds its expression in the tendency to fully
polymerise by elimination of hydrogen chloride and consequent
hydrazinium salt formation over a few hours even at -25 ◦C. Thus
we were not capable of obtaining single crystals of this compound.
Among all compounds in this paper it shows the most low-
Hydrogen bridges between the N–H functions of one molecule
and the NMe2 groups of the other lead to the formation of ladder
type endless aggregates as displayed in Fig. 7. There are two sorts
of N–H ◊ ◊ ◊ N bonding with shorter and longer N ◊ ◊ ◊ H distances
˚
˚
˚
(N(1)–H(1 N)–N(4A): N ◊ ◊ ◊ H 2.60(3) A, N ◊ ◊ ◊ N 3.376(4) A,
N–H–N 172(3)◦ and N(3)–H(3 N)–N(2B): N ◊ ◊ ◊ H 2.51(3) A,
1
◦
˚
field shifted H NMR resonance for its NH proton (2.42 ppm),
N ◊ ◊ ◊ N 3.303(4) A, N–H–N 169(3) ). This hydrogen bonding
motif is very similar to that in 2 (with two methyl groups at silicon,
see Figs. 2 and 3) and therefore probably the reason for the disorder
of the single methyl group and hydrogen atom at silicon in 9 to
both possible sides of the molecule.
along with the highest frequency for the N–H stretching mode
(3300 cm-1). Compound 8 also shows the most low-field shifted
1H NMR resonance for its SiH proton (5.17 ppm) accompanied
by the highest frequency for the Si–H stretching mode (2218 cm-1)
among the Si–H functional silanes described in this contribution
(see following text).
Me2HSi(NHNMe2) (10). The reaction of UMDH with
chlorodimethylsilane ClHSiMe2 gave Me2HSi(NHNMe2) 10 as a
colourless liquid, which is very sensitive to hydrolysis. Crystallisa-
tion for a structural analysis of 10 could not be achieved. It was
characterised by NMR and IR spectroscopy (see Table 1), mass
spectrometry and elemental analysis.
Me(H)Si(NHNMe2)2 (9). Much more stable than 8 is com-
pound 9. This compound has already been described in the
literature1 and we have resynthesised it by reacting dichloromethyl-
silane with UDMH.
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substantial amounts of substances of lower volatility and the large
number of signals observed in NMR investigations showed these
to consist probably of polymers containing Si–H, Si–Cl and Si–
N–N functions. Further separation of these residues could not be
achieved.
The constitution of 11 was proven by NMR spectroscopy (1H,
13C, 29Si) and IR spectroscopy (Table 1). The 1H NMR spectrum
shows two singlet resonances of the NMe-groups with an integral
ratio of 4:1. The proton resonance of the H–Si groups is a multiplet
at 4.79 ppm. In the 29Si NMR spectrum, both silicon nuclei give one
doublet at -45.8 ppm with a 1JSiH coupling constant of 211 Hz. The
infrared spectrum shows two sharp bands for the Si–H stretching
mode at 2135 cm-1 and a broad band for the N–H stretching mode
at 3300 cm-1.
Fig. 7 Aggregation of 9 in the crystal showing the weak hydrogen
bonding. Hydrogen atoms except those bound to N are omitted for clarity.
Symmetry operations for generating neighbour molecules, A: -x + 2,
-y + 1, -z; B: -x + 2, -y,-z.
A crystal structure of 11 was obtained by X-ray diffraction
with a single crystal in the form of colourless plates grown from
hexane solution at -25 ◦C. Fig. 8 presents the molecular structure
of 11. The crystals contain two independent molecules in the
Me2HSiCl + 2 H2NNMe2 →
Me2HSi(NHNMe2) (10) + [H3NNMe2]Cl
¯
asymmetric unit of a triclinic P1 cell.
Me2NN[HSi(NHNMe2)2]2 (11) and Si(NHNMe2)4 (12). Un-
expectedly, the reaction of trichlorosilane, HSiCl3, with
UMDH did not lead to the formation of tris(N¢,N¢-
dimethylhydrazido)silane, HSi(NHNMe2)3. Instead two prod-
ucts were formed, N¢,N¢-bis[bis(2¢,2¢dimethylhydrazido)silyl]-2,2-
dimethylhydrazine, Me2NN[HSi(NHNMe2)2]2 (11) by double
deprotonation of one molecule of UDMH, and tetrakis(1,1-
dimethylhydrazino)silane (12) by loss of one equivalent of hy-
drogen.
2 HSiCl3 + 11 H2NNMe2 →
Me2NN[HSi(NHNMe2)2]2 (11) + 6 [H3NNMe2]Cl
HSiCl3 + 7 H2NNMe2 →
Si(NHNMe2)4 (12) + 3 [H3NNMe2]Cl + H2
Fig. 8 Molecular structure of 11 in the crystal. Ellipsoids are drawn at
the 50% level, hydrogen atoms except those bound to N and Si are omitted
for clarity.
The composition of the product depends on the employed
ratio between UDMH and HSiCl3. Compound 11 is yielded
preferentially by the reaction of two equivalents of HSiCl3 with
eleven equivalents of DMH. The formation of the 11 can be ex-
plained by the condensation of two molecules of the intermediate
(N¢,N¢-dimethylhydrazido)chlorosilane, HSiCl(NHNMe2)2, with
an UDMH molecule according to a similar mechanism to the one
described by Voronkov and co-workers1 for analogous cases.
The doubly silicon-bonded atom N(1) has much longer
˚
bond lengths to the silicon atoms Si(1) (1.731(2) A) and Si(2)
˚
˚
(1.737(1) A) and to the nitrogen atom N(2) (1.462(2) A) than
the other silicon bound nitrogen atoms, which show average Si–N
˚
˚
distances of 1.692 A and N–N distances of 1.423 A.
Due to steric reasons the Si1–N1–Si2 angle is widened to
nearly 130◦. The planar coordination sphere of the nitrogen atom
N(1) compensates for this by a compressed angle N2–N1–Si1
of 109.6(1)◦, while the angle N2–N1–Si2 is 120.3(1)◦. It might
be speculated whether a weak b-Si ◊ ◊ ◊ N attractive interaction
between Si(1) and N(2) might also responsible for this deformation
of the coordination sphere of N(1).
The environments of the silicon atoms are quite distorted
tetrahedrons with some N–Si–N angles widened to over 117◦,
whereas others are compressed to 102◦ (Table 6). This effect
was observed in some of the other structures in this paper and
also other element amides and can be rationalised by Gillespie’s
ligand close packing model, with ligands, that are far from
rotational symmetry like amide groups due to the presence of
two substituents (here H and N) and one lone pair of electrons.18
HSiCl3 + 4 H2NNMe2 →
HClSi(NHNMe2)2 + 2 [H3NNMe2]Cl
2 HClSi(NHNMe2)2 + 3 H2NNMe2 →
Me2NN[Si(NHNMe2)2]2 (11) + 2 [H3NNMe2]Cl
However, this represents only one possibility and does not
explain at which step of the substitution of the Si–Cl functions of
one HSiCl3 molecule the formation of the Si–N–Si bridge occurs.
The yields of the preparations of 11 and 12 are comparatively
low and attempts of investigation of other products formed were
difficult. The residues of distillations showed the occurrence of
5304 | Dalton Trans., 2009, 5300–5309
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˚
˚
Table 6 Selected structural parameters (A, deg) of Me2NN[HSi-
Table 8 Selected structural parameters (A, deg) of Si(NHNMe2)4 (12).
Symmetry transformations used to generate equivalent atoms: -x + 1,
y, -z + 3/2
(NHNMe2)2]2 (11)
Si(1)–N(1)
Si(2)–N(1)
Si(1)–N(3)
Si(1)–N(5)
Si(2)–N(7)
Si(2)–N(9)
N(1)–N(2)
N(3)–N(4)
N(5)–N(6)
N(7)–N(8)
N(9)–N(10)
Si(1)–H(1)
Si(2)–H(2)
1.731(2)
1.737(2)
1.690(2)
1.690(2)
1.687(2)
1.701(2)
1.462(2)
1.421(3)
1.424(3)
1.421(3)
1.424(3)
1.33(2)
N(2)–N(1)–Si(1)
N(2)–N(1)–Si(2)
Si(1)–N(1)–Si(2)
N(4)–N(3)–Si(1)
N(6)–N(5)–Si(1)
N(8)–N(7)–Si(2)
N(10)–N(9)–Si(2)
N(5)–Si(1)–N(3)
N(5)–Si(1)–N(1)
N(3)–Si(1)–N(1)
N(5)–Si(1)–H(1)
N(3)–Si(1)–H(1)
N(1)–Si(1)–H(1)
N(7)–Si(2)–N(9)
N(7)–Si(2)–N(1)
N(9)–Si(2)–N(1)
N(7)–Si(2)–H(2)
N(9)–Si(2)–H(2)
N(1)–Si(2)–H(2)
109.6(1)
120.3(1)
129.4(1)
125.5(2)
121.7(2)
120.3(2)
120.5(2)
112.0(1)
117.3(1)
101.9(1)
102.1(8)
115.6(8)
108.6(8)
114.9(1)
103.7(1)
115.2(1)
112.5(8)
99.7(8)
Si(1)–N(3)
Si(1)–N(1)
N(1)–N(2)
N(3)–N(4)
1.700(2)
1.705(2)
1.432(3)
1.423(3)
N(3A)–Si(1)–N(3)
N(3A)–Si(1)–N(1)
N(3)–Si(1)—N(1)
N(1)–Si(1)—N(1A)
N(2)–N(1)–Si(1)
N(4)–N(3)–Si(1)
100.1(2)
114.3(1)
114.8(1)
99.4(2)
120.7(2)
121.6(2)
loss of hydrogen in the reaction of trichlorosilane with compounds
bearing acidic protons is well known. It has to be noted that
compound 12 has already been described in the literature,19 but
then obtained from the reaction of SiCl4 with H2NNMe2 and
less completely characterised. After contact with air 12 forms an
insoluble polymeric solid.
The constitution of compound 12 was proven by an 1H NMR
spectrum, which shows only one broad signal for the NH-groups
at 2.16 ppm and one signal for the NMe2-groups at 2.34 ppm with
an integral ratio of 1:6.
Fig. 10 shows the molecular structure of 12 in the solid
state. Structural parameter values are listed in Table 8. The
compound crystallizes at -25 ◦C from hexane solutions in the
monoclinic space group P2/c. It contains two crystallographically
independent molecules in the unit cell, which are of very similar
geometry. This allows the conclusion that structural features are
not imposed by packing forces.
1.34(2)
111.2(9)
˚
Table 7 Hydrogen bonding parameters (A, deg) of the dimers of
Me2NN[HSi(NHNMe2)2]2 (11)
N1
N2
N1 ◊ ◊ ◊ N2
N1-H
H ◊ ◊ ◊ N2
N1–H–N2
N(3)
N(5)
N(7)
N(10)
N(12)
N(6)
3.004(3)
3.256(3)
3.332(3)
3.290(3)
3.133(3)
3.334(3)
0.72(2)
0.72(2)
0.80(2)
0.72(2)
0.76(2)
0.81(2)
2.29(2)
2.55(2)
2.57(2)
2.58(2)
2.39(2)
2.56(2)
171(2)
168(2)
161(2)
168(2)
166(2)
159(2)
N(13)
N(15)
N(19)
N(2)
N(18)
N(14)
The repulsion between these in different conformations leads to
this highly distorted coordination geometry.
Weak hydrogen bonds of the N–H ◊ ◊ ◊ N type link the two
independent molecules of 11 to give unsymmetrical dimers (Fig. 9).
In addition to this intermolecular hydrogen bonding there are
also two intramolecular weak hydrogen bonds in each monomer
leading to the formation of seven-membered HNSiNSiNN rings.
The details of this hydrogen bonding pattern is listed in Table 7.
The terminal N–H function at N(9) is not involved in such
hydrogen bonding, as the shortest distances of this H atom to
˚
neighbouring N atoms of other molecules are far longer than 3 A.
Fig. 10 Molecular structure of 12 in the crystal. Ellipsoids are drawn
at the 50% level; hydrogen atoms except those bound to N are omitted
for clarity. Only one of two independent molecules is shown. Symmetry
transformations used to generate equivalent atoms: -x + 1, y, -z + 3/2.
The Si–N bond lengths are in the expected range. The N–N
distances are again, as in the other hydrazidosilanes, comparatively
short. Despite the presence of four identical substituents, the
coordination geometry at the silicon atom is that of a substantially
distorted tetrahedron. This can be rationalised by Gillespie’s lig-
and close packing model under consideration of a local asymmetry
of the binding atoms at silicon.20
Fig. 9 Inter- and intramolecular aggregation of 11 showing hydrogen
bonded dimers in the crystal. Only hydrogen atoms bound to N and Si are
shown.
Compound 12 can be obtained preferentially in yields up to 30%
by reacting seven equivalents of UDMH with one of HSiCl3. The
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Fig. 11 shows that 12 has a different aggregation motif by
hydrogen bonds than the other compounds in this contribution.
Here we find a total of eight interactions between the NH functions
to two neighbour molecules, leading to the formation of endless
aggregation polymers. In contrast to the other compounds the
nitrogen atoms involved in hydrogen bonding here are the silicon-
bonded ones (not the NMe2 groups), which can be regarded as
less basic due to their planar coordination geometry. As the NH
functions serve at the same time as acceptors and donors, the
resulting network contains strongly bent hydrogen bonds with
N–H ◊ ◊ ◊ N angles of 152 and 154◦.
Me2NN[HSi(NHNMe2)2] (11), there are still four N–H functions
left in the presence of two Si–H groups.
Only for the reaction of UDMH with HSiCl3 we have observed
the activation of an Si–H bond under the reaction conditions. This
led finally to a fourfold substitution of HSiCl3 and the formation
of Si(NHNMe2)4 (12) under liberation of H2.
The compounds, which have been structurally studied, have
some common features. As expected all silylated nitrogen atoms
are of planar coordination geometry and the N–N bond lengths
in the compounds under investigation are generally short in
comparison to silylhydrazines, which bear more than one silicon
atom at the N–N unit. The presence of N–H functions makes
hydrogen bonding a common motif for intermolecular aggre-
gation. However, in all cases with such N–H ◊ ◊ ◊ N bonds, these
are relatively long and have to be categorised as weak. They are
normally found between the N–H functions as hydrogen bond
donors and the NMe2 groups as hydrogen bond acceptors. Only for
Si(NHNMe2)4 (12) the weak hydrogen bonds are found between
the N–H groups of one and the silylated N atoms of a neighbouring
molecule.
Experimental
General remarks
All reactions were carried out under dry nitrogen atmosphere in
anhydrous and degassed solvents using Schlenk line techniques.
N,N -Dimethylhydrazine (UMDH) was dried over calcium hydride
and distilled. NMR spectra were detected on a Bruker Avance
400 instrument and were referenced relative to (residual) solvents
resonance (1H, 13C) or relative to an external standard [29Si; SiMe4].
Infrared spectra were recorded on a Midac Prospect-IR or on a
Shimadzu IR-Prestige-21 spectrometer. Mass spectra from solid
compounds were obtained on a Varian Mat 212, mass spectra of
volatile compounds with a Pfeiffer QMG 422, which was directly
connected to a Stock high vacuum line. Elemental analyses were
performed using an Elementar Vario EL III CHNS analyser.
Fig. 11 Aggregation of 12 into endless strands by four hydrogen
bridges between each pair of monomers. Only the hydrogen bound to N
˚
are shown. Structural parameters are: N(5A)–H 0.82(2) A, N(7B) ◊ ◊ ◊ H
2.61(3) A, N(5A)–H–N(7B) 152(2)◦, N(5A) ◊ ◊ ◊ N(7B) 3.356(3) A;
˚
˚
◦
˚
˚
N(7B)–H 0.80(3) A, N(5AA) ◊ ◊ ◊ H 2.62(3) A, N(7B)–H–N(5AA) 154(3) ,
N(7B) ◊ ◊ ◊ N(5AA) 3.350(3) A. Symmetry operations for generating neigh-
General procedure for compounds 1, 2, 5, 9, 11 and 12. To a
stirred solution of UMDH dissolved in a hydrocarbon solvent the
halosilane (quantities given below) was added dropwise at 273 K
(1, 2) or 233 K (5, 9, 11, 12). The reaction mixtures were slowly
allowed to warm to ambient temperature (in the case of 1 and 2
they were stirred afterwards for 1 h and then refluxed for 3 h to
ensure complete substitution) and the precipitated hydrazinium
salts were filtered off. The solvents were distilled off and the
liquid products were purified by fractional distillation. Crystals
were grown from relatively concentrated solutions of the pure
compounds in hexane at -25 ◦C.
˚
bour molecules, A: x, y - 1, z.
Conclusions
We have reported the synthesis of some classes of hydrazidosilanes,
namely those with organic substituents at silicon and different
numbers of hydrazide units, hydrazidosilanes with Si–Cl and with
Si–H functions. As all compounds contain the Me2NNH- unit,
the latter two classes of compounds simultaneously contain two
reactive groups capable of undergoing condensation reactions
with release of HCl or hydrogen. All Si–Cl group containing
compounds were found to be unstable towards such reactions,
which they undergo even at low temperatures. Only in one case, for
PhClSi(NHNMe2)2 (5) it was possible to isolate such a compound
with the SiCl-NH-N unit in completely pure form as single crystals
and to obtain a crystal structure. The compounds containing
SiH-NH-N units are much more stable. It is interesting to see,
that only in one case the double N–H functional Me2NNH2 was
doubly silylated at the nitrogen atom. But even for this compound,
Ph2Si(NHNMe2)2 (1). UMDH (16.7 mL, 0.22 mol in 20 mL
hexane), dichlorodiphenylsilane (2.4 mL 0.10 mol in 10 mL
hexane). Colourless needles; yield 60%; m.p. 40 ◦C, b.p. 191 ◦C
(13 mbar) (Found C, 63.38; H, 7.80; N, 18.61. C16H24N4Si [300.48]
requires C 63.92, H 8.05, N 18.65); dH(400.13 MHz, C6D6, 21◦C)
2.34 (2H, br s, NH), 2.40 (12H, s, NMe), 7.29 (2H, s, o-H), 7.34
(2H, s, m-H), 7.97 (1H, s, p-H); dC(100.62 MHz, C6D6, 21◦C) 52.4
(2 C, NMe), 129.7 (o-C), 135.6 (m-C), 135.8 (p-C); dSi(79.49 MHz,
C6D6, 21◦C) -38.6; n(Nujol) 3278 (n(NH)) cm-1; m/z(EI, 20 eV,
5306 | Dalton Trans., 2009, 5300–5309
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◦
50 C) 300 (M+), 256 (M+ - NMe2), 241 (M+ - NHNMe2), 197
C6D6, 21◦C) 2.00 (s, 3H, NH), 2.43 (s, 18H, NMe2), 7.30 (s, 2H,
o-H),7.74 (s, 2H, m-H), 7.75 (s, 1H, p-H); dC(100.62 MHz, C6D6,
21◦C) 51.6 (s, NMe2), 128.5 (s, o-C), 130.1 (s, m-C), 135.3 (s, p-C);
dSi(79.49 MHz, C6D6, 21◦C) -22.2; n(film) 3293 (s, ns(NH)), 2980,
2891, 2850, 2827 (vs, n(CH)), 1950, 1880, 1860, 1620 (s), 1460 (s,
das(CH3)), 1455, 1393 (vs, n(SiN)), 1233 (s, n(SiC)), 1149, 1116,
1075 (vs), 1001 (s), 882 (s), 732, 701 (s) cm-1.
(M+ - NH(NMe2)2), 59 (NHNMe2).
Me2Si(NHNMe2)2 (2). UMDH (24.4 mL, 0.32 mol in 40 mL
hexane), dichlorodimethylsilane (2.4 mL 0.10 mol in 20 mL
hexane). Colourless needles; yield 51%; b.p. 60 ◦C (28 mbar)
(Found C, 40.99; H, 11.76; N, 32.02. C6H16N4Si [172.31] requires
C, 40.87; H, 11.43; N, 31.77); dH(400.13 MHz, C6D6, 21 ◦C)
-0.12 (6H, s, SiMe), 2.04 (2H, br s, NH), 2.25 (12H, s, NMe);
dC(100.62 MHz, C6D6, 21 ◦C) -3.6 (2 C, SiMe), 52.4 (4 C, NMe);
MeSi(NHNMe2)3 (4). A solution of trichloromethylsilane
(2.3 mL, 0.02 mol) in hexane (10 mL) was added dropwise
to a solution of N,N -dimethylhydrazine (16.0 mL, 0.20 mol) at
ambient temperature. After stirring the mixture for 24 h, it was
heated to reflux for 4 h. The precipitated hydrazonium salts were
removed by filtration. The initially obtained product is an air-
and moisture-sensitive liquid, which crystallis◦es from concentrated
hexane solution. Yield 2.7 g (60%); m.p. 55 C (Found C, 38.16;
H, 11.12; N, 38.45. C7H24N6Si [220.40] requires C, 38.15; H, 10.98;
N, 38.13); dH(400.13 MHz, CDCl3, 21 ◦C) 0.32 (s, 3H, SiMe), 2.08
(s, 3H, NH), 2.29 (s, 18H, NMe2); dC(100.62 MHz, CDCl3, 21 ◦C)
◦
dSi(79.49 MHz, C6D6, 21 C) -13.6; n(Nujol) 3278 (NH) cm-1;
m/z(EI, 70 eV, 50 ◦C) 176 (M+).
PhClSi(NHNMe2)2 (5). UMDH (9.1 mL, 0.12 mol in 20 mL
toluene), trichlorophenylsilane (3.2 mL 0.02 mol in 20 mL
toluene). Colourless blocks; yield 65% (Found C, 25.41; H, 10.11;
N, 29.86. C6H16N4Si [186.76] requires C, 25.72; H, 10.25; N, 30.00);
dH(400.13 MHz, C6D6, 21◦C) 2.23 (12H, s, NMe), 2.37 (2H, s,
NH), 7.23 (2H, s, o-H), 8.01 (2H, s, m-H), 8.18 (1H, s, p-H).
dC(100.62 MHz, C6D6, 21◦C) 52.6 (NMe), 130.6 (o-C), 134.1
(m-C), 135.2 (p-C). dSi(79.49 MHz, C6D6, 21 ◦C) ◦1.7; n(Nujol)
3284 (n(NH)), 516 (n(SiCl)) cm-1; m/z(EI, 70 eV, 50 C) 258 (M+),
223 (M+ - Cl), 214 (M+–NMe2), 199 (M+ - NHNMe2), 92 (M+ -
(NMe2)2), 59 (M+ - SiClNHNMe2), 44 (NMe2).
◦
-4.3 (SiMe), 52.7 (NMe2). dSi(79.49 MHz, CDCl3, 21 C) -28.9;
n(film) 3275 (s, ns(NH)), 2969, 2890, 2800 (vs, n(CH)), 1540, 1530
(vs), 1466 (s, das(CH3)), 1382 (vs, n(SiN)), 1260, 1230 (w, n(SiC)),
1097, 1085, 1070 (vs), 879 (w), 816 (s), 730 (s) cm-1.
MeClSi(NHNMe2)2 (6).
A
solution of N,N-dimethyl-
MeHSi(NHNMe2)2 (9). UMDH (9.1 mL, 0.12 mol in 20 mL
hexane), dichloromethylsilane (3.8 mL 0.03 mol in 10 mL hexane).
Colourless needles, yield 43%; b.p. 59 ◦C (22 mbar) (Found C,
36.87; H, 11.42; N, 34.74. C5H18N4Si [162.31] requires C, 37.00;
H, 11.18; N, 34.52); dH(400.13 MHz, C6D6, 21 ◦C) 0.29 (3H, s,
SiMe), 2.22 (2H, br s, NH), 2.36 (12H, s, NMe), 4.78 (1H, m,
SiH); dC(100.62 MHz, C6D6, 21 ◦C) -5.1 (SiMe), 51.8 (NMe);
dSi(79.49 MHz, C6D6, 21 ◦C) -28.4; n(gas) 3278 (s, br, n(NH)),
2131 (s, n(SiH)) cm-1.
hydrazine (6.0 mL, 0.08 mol) in hexane (20 mL) was slowly
added to a solution of trichloromethylsilane (2.3 mL, 0.02 mol)
◦
in hexane (20 mL) at -40 C. The mixture was allowed to warm
to ambient temperature and filtered. The solvent was removed
by distillation under slightly reduced pressure. The product is
a colourless liquid, which is very sensitive to hydrolysis. It
polymerises within a few hours at ambient temperature. Yield 2.2 g
(57%), dH(400.13 MHz, CDCl3, 21 ◦C) 0.60 (s, 3H, SiMe), 2.28 (s,
◦
12H, NMe2), 2.39 (s, 2H, NH); dC(100.62 MHz, CDCl3, 21 C)
Me2NN[HSi(NHNMe2)2] (11). UMDH (9.1 mL, 0.12 mol in
20 mL hexane), trichlorosilane (2.0 mL 0.02 mol in 10 mL hexane).
Colourless plates; yield 27%; m.p. 80 ◦C (Found C, 34.98; H,
10.18; N, 38.89. C10H36N10Si2 [352.63] requires C, 34.06; H, 10.29;
N, 39.72); dH(400.13 MHz, C6D6, 21◦C) 2.18 (4H, br s, NH),
2.33 (24H, s, NHNMe), 2.37 (6H, s, NNMe), 4.79 (2H, m, SiH);
dC(100.62 MHz, C6D6, 21 ◦C) 48.7 (NNMe), 52.4 (NHNMe);
3.8 (s, SiMe), 51.8 (s, NMe2); dSi(79.49 MHz, CDCl3, 21 ◦C) -6.8;
n(film) 3268 (s, ns(NH)), 2970, 2910, 2870, 2780 (vs, n CH), 1470
(s, das(CH3)), 1440, 1385 (vs, n(SiN)), 1240 (s, n(SiC)), 1150, 1141,
1073 (vs), 1009 (s), 892 (s), 732, 699 (s), 529 (s, ns(SiCl)), 108 cm-1.
Me2ClSi(NHNMe2) (7). A solution of N,N -dimethylhydrazine
(12.2 mL, 0.16 mol) in diethyl ether (15 mL) was dropped slowly
into a solution of dichlorodimethylsilane (9.7 mL, 0.08 mol) in
diethyl ether (55 mL) at -40 ◦C. The mixture was allowed to
reach ambient temperature and the solution was separated from
the precipitate by a cannula fitted with a filter. The solvent is
evaporated under slightly reduced pressure. An oily product was
obtained, which could not be further purified due to its instability.
Yield 14.6 g (60%); dH(400 MHz, CDCl3, 21 ◦C) 0.45 (s, 6H,
SiMe2), 2.36 (s, 1H, NH), 2.45 (s, 6H, NMe2); dC(100 MHz,
CDCl3, 21 ◦C) 0.9 (s, SiMe2), 51.8 (s, NMe2); dSi(79.49 MHz,
CDCl3, 21 ◦C) 8.5; n(film) 3284 (s, ns(NH)), 2980, 2867 (vs, n(CH)),
1454 (s, das(CH3)), 1390, 1381 (vs), 1366, 1350 (s, n(SiN)), 1290,
1267 (w, n(SiC)), 1132 (vs), 1074 (s), 852 (s), 742 (w), 568 (s,
ns(SiCl)) cm-1.
◦
1
dSi(79.49 MHz, C6D6, 21 C) -45.8 (d, JSiH = 211 Hz); n(gas)
3275 (s, br, n(NH)), 2146 (s, n(SiH)) cm-1.
Si(NHNMe2)4 (12). UMDH (15.2 mL, 0.20 mol in 20 mL
hexane), trichlorosilane (2.0 mL 0.02 mol in 15 mL hexane).
Colourless needles; yield 30%; m.p. 64 ◦C (Found C, 37.45; H,
10.86; N, 42.76. C8H28N8Si [264.45] requires C, 36.34; H, 10.67;
N, 42.37); dH(400.13 MHz, C6D6, 21◦C) 2.16 (4H, br s, NH),
◦
2.34 (24H, s, NMe); dC(100.62 MHz, C6D6, 21 C) 52.7 (NMe);
dSi(79.49 MHz, C6D6, 21 ◦C) -45.9; n(gas) 3300 (s, br, n(NH)) cm-1.
PhSi(NHNMe2)3 (3). Trichlorophenylsilane (3.2 mL, 0.02 mol)
was added dropwise to a solution of N,N -dimethylhydrazine
(9.1 mL, 0.12 mol) at ambient temperature. After stirring the
mixture for 24 h, it was heated to reflux for 6 h. The precipitated
hydrazonium salts were removed by filtration. The solvents were
evaporated under reduced pressure, leading to precipitation of the
product, which is an air- and moisture-sensitive solid. Yield 2.1 g
(37%), m.p. 75 ◦C (Found C, 52.12; H, 9.43; N, 28.98. C12H26N6Si
[282.47] requires C, 51.03; H, 9.28; N, 29.75); dH(400.13 MHz,
MeClHSi(NHNMe2) (8). A solution of dichloromethylsilane
(10.4 mL, 0.10 mol) in diethyl ether (50 mL) was slowly dropped
to a solution of N,N-dimethylhydrazine (15.0 mL, 0.20 mol) in
diethyl ether (20 mL) at -40 ◦C. The mixture was allowed to
reach ambient temperature. The precipitated hydrazonium salt
was filtered off and the diethyl ether solvent was removed by careful
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Table 9 Data for the single crystal X-ray diffraction of compounds 1, 2, 5, 9, 11 and 12
1
2
5
9
11
12
Formula
Mr
C16H24N4Si
300.48
triclinic
¯
P1
8.830(2)
9.907(2)
10.182(2)
93.77(2)
91.31(2)
98.49(2)
878.5(3)
1.136
C6H20N4Si
176.35
triclinic
¯
P1
8.239(8)
8.702(9)
8.730(9)
117.44(2)
97.65(2)
92.13(2)
547.1(9)
1.071
C10H19ClN4Si
258.83
C5H18N4Si
162.32
triclinic
¯
P1
8.326(5)
8.332(5)
9.182(5)
68.92(1)
89.16(1)
60.69(1)
507.9(5)
1.061
C10H36N10Si2
352.67
triclinic
¯
P1
11.121(5)
11.644(6)
16.611(8)
80.46(1)
89.01(1)
84.81(1)
2112.5(18)
1.109
C8H28N8Si
264.47
monoclinic
Crystal system
Space group
orthorhombic
P212121
8.972(1)
12.116(1)
12.904(1)
90
90
90
1402.6(2)
1.226
4
153(2)
3.084
0.934/0.349
CuKa
144.8
P2/c
˚
a/A
17.998(5)
5.015(1)
18.163(5)
90
109.46(1)
90
1545.8(7)
1.136
4
153(2)
0.149
0.994/0.939
MoKa
51.0
˚
b/A
˚
c/A
a/◦
b/◦
l/◦
3
˚
V/A
Dc/g cm-3
Z
2
2
2
4
T/K
163(2)
0.134
—
MoKa
54.0
13667
153(2)
0.172
0.921/0.983
MoKa
48.0
153(2)
0.180
0.919/0.986
MoKa
55.0
153(2)
0.181
0.931/0.993
MoKa
50.0
m/mm-1
T
min/max
Radiation
◦
2qmax
Refls. collected
/
2368
8190
4763
16414
11890
Refls. unique
Refls. observed (|Fo| > 4s |Fo|)
Rint
Parameters/restraints
R1[I > 2s (I)]/wR2
R1/wR2 (all data)
rfin (min/max)/e A
Flack parameter
CCDC no.
3509
2633
1600
1192
0.0405
114/0
0.0591/0.1416
0.0845/0.1551
–0.384/0.566
—
2651
2338
0.0358
157/0
0.0451/0.1093
0.0528/0.1154
–0.273/0.527
0.01(2)
715613
2313
1528
0.0576
117/0
0.0527/0.1207
0.0907/0.1340
–0.429/0.321
—
7431
5367
0.0367
465/0
0.0466/0.1141
0.0710/0.1241
–0.358/0.514
—
2864
1974
0.0676
179/0
0.0497/0.1137
0.0833/0.1293
–0.327/0.472
—
0.1390
194/0
0.0717/0.1820
0.0995/0.2056
–0.608/0.704
—
3
˚
715611
715612
715614
715615
715616
distillation. The product is a colourless air- and moisture-sensitive
liquid, which decomposes upon keeping it at ambient temperature
or upon attempts of further purification by distillation. Yield 4.1 g
Single-crystal X-ray diffraction experiments. Single crystals
of compounds were mounted under inert perfluoropolyether at
the tip of a glass fibre and cooled in the cryostream of the
diffractometer. Crystallographic data sets were collected on an
IPDS-1 (Fa. Stoe) (1), Bruker Smart CCD diffractometer (2, 5, 11
and 12) and a Bruker APEX CCD diffractometer (9) Crystal and
refinement data are listed in Table 9. Structures were solved with
the programs SHELXS21 with direct methods and refined with
SHELXL.22 All non-hydrogen atoms were refined anisotropically.
In the case of 1 protons at the silicon and nitrogen atoms were
placed in calculated positions and included in the refinement, for
2, 5, 9, 11 and 12 they were located in difference Fourier maps and
refined isotropically. The molecular graphics were prepared with
ORTEP3.23
(30%); dH(400.13 MHz, CDCl3, 21 ◦C) 0.61 (d, 3H, SiMe, 3JHCSiH
=
2.5 Hz), 2.42 (s, 1H, NH), 2.69 (s, 6H, NMe2), 5.17 (dq, 1H,
SiH). dC(100.62 MHz, CDCl3, 21◦C) 1.8 (s, SiMe), 48.1 (s, NMe2).
◦
1
dSi(79.49 MHz, CDCl3, 21 C) -19.5 (d, JSiH = 195 Hz). n(gas)
3300 (s, ns(NH)), 2988, 2870 (vs, n(CH)), 2218 (s, nas (SiH)), 2189
(s, ns(SiH)), 1450 (s, das(CH3)), 1392, 1381 (vs), 1348 (s, n(SiN)),
1294, 1265 (w, n(SiC)), 1138 (vs), 1074 (s), 860 (s, das(SiH)), 852
(s, ds(SiH)), 742 (w), 565 (s, ns(SiCl)) cm-1.
Me2HSi(NHNMe2) (10). A solution of chlorodimethylsilane
(11.1 mL, 0.10 mol) in diethyl ether (10 mL) was slowly added
to a solution of N,N-dimethylhydrazine (16.0 mL, 0.22 mol) at
0 ◦C. The mixture was allowed to warm to ambient temperataure
and was stirred for 4 h. The mixture was filtered from the
hydrazonium salts. The diethyl ether was carefully dis◦tilled off.
Distillation of the residue gave the pure product at 74 C under
normal pressure. Yield 9.9 g (84%) (Found C, 39.98; H, 12.01; N,
23.48. C4H14N2Si [118.25] requires C, 40.63; H, 11.93; N, 23.69);
dH(400.13 MHz, C6D6, 21 ◦C) 0.14 (d, 6H, SiMe, 3JHCSiH = 3.0 Hz),
1.81 (s, 1H, NH), 2.22 (s, 6H, NMe2), 4.67 (dsept, 1H, SiH,
3JHSiNH = 1.0 Hz, 3JHSiCH = 3.0 Hz); dC(100.62 MHz, C6D6, 21◦C)
-2.6 (SiMe), 51.7 (NMe); dSi(79.49 MHz, C6D6, 21 ◦C) -14.7
Notes and references
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(d, JSiH = 193.5 Hz); n(gas) 3285 (w, n(NH)), 2992, 2963, 2856,
2818 (vs, n(CH)), 2135 (s, nas(SiH)), 2112 (s, ns(SiH)), 1456 (w,
das(CH3)), 1377, 1324 (w, n(SiN)), 1255 (s, n(SiC)), 1068 (w), 918
(s, das(SiH)), 898 (s, ds(SiH)), 837 (w), 735 (vs) cm-1; m/z (EI, 70
eV) 118 (M+), 103 (M+–Me), 88 (M+–2Me), 59 (M+ - Me2SiH),
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5308 | Dalton Trans., 2009, 5300–5309
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