Synthesis of di- and trisilanes with potentially chelating substituents

Article abstract of DOI:10.1016/S0022-328X(01)01451-6

Silylenes 2 or 4, generated by thermolysis of cyclotrisilanes 1 and 3, were inserted into the Si-Cl or Si-H bonds of monosilanes to yield a variety of disilanes, which can be further functionalized subsequently. In a few cases, trisilanes are accessible by the reaction of 1 with disilanes. The reaction of a metalated silane with a chlorosilane is an alternative method for the formation of Si-Si bonds, which turned out to be especially useful for the synthesis of bulkily substituted disilanes. Some of the new dichlorodiand trisilanes themselves serve as thermal precursors of silylenes 2 or 4, the extrusion of which can be catalyzed by 1 or 3 in certain cases.

Full text of DOI:10.1016/S0022-328X(01)01451-6

Journal of Organometallic Chemistry 649 (2002) 25–42
www.elsevier.com/locate/jorganchem
Synthesis of di- and trisilanes with potentially chelating
substituents
Johannes Belzner a,1*, Uwe Dehnert a, Dirk Scha¨r a, Bernhard Rohde a, Peter Mu¨ller b,
Isabel Uso´n b
a Institut fu¨r Organische Chemie der Georg-August-Uni6ersita¨t Go¨ttingen, Tammannstr. 2, D-37077 Go¨ttingen, Germany
b Institut fu¨r Anorganische Chemie der Georg-August-Uni6ersita¨t Go¨ttingen, Tammannstr. 4, D-37077 Go¨ttingen, Germany
Received 3 April 2001; received in revised form 29 May 2001; accepted 29 October 2001
Abstract
Silylenes 2 or 4, generated by thermolysis of cyclotrisilanes 1 and 3, were inserted into the SiꢀCl or SiꢀH bonds of monosilanes
to yield a variety of disilanes, which can be further functionalized subsequently. In a few cases, trisilanes are accessible by the
reaction of 1 with disilanes. The reaction of a metalated silane with a chlorosilane is an alternative method for the formation of
SiꢀSi bonds, which turned out to be especially useful for the synthesis of bulkily substituted disilanes. Some of the new dichlorodi-
and trisilanes themselves serve as thermal precursors of silylenes 2 or 4, the extrusion of which can be catalyzed by 1 or 3 in certain
cases. © 2002 Elsevier Science B.V. All rights reserved.
Keywords: Silylenes; Oligosilanes; Halosilanes; Siliconꢀsilicon bond formation
crucial intermediate—to the formation of symmetri-
cally substituted disilanes [1]. In contrast, geminally
dihalogenated silanes do not serve as synthetically use-
ful starting material for disilanes. When treated with
metals, they are transformed to either polysilanes [2] or,
in the case of dihalosiloles, to silole dianions [3]; 1,2-di-
halodisilanes could be isolated from the reaction mix-
1. Introduction
Two principal reaction pathways are available for the
formation of SiꢀSi bonds (Scheme 1). The nucleophilic
attack of a metalated silane on a silicon center, which
bears a leaving group, or, alternatively, the insertion of
a silylene into a SiꢀX bond (XꢁH or Hal). The first
method in particular, a Wurtz-type coupling reaction,
was used repeatedly for the synthesis of disilanes.
Reacting a monohalogenated silane with metals such
as Li, Na, or Mg gives rise—via a metalated silane as
ture only in
a few cases [4]. Unsymmetrically
substituted disilanes are in general synthesized by reac-
tion of a preformed metalated silane with a halosilane
[5], although it was reported that treatment of a mix-
ture of two different halosilanes with lithium may result
in the formation of unsymmetrical disilanes in good
yield [6]. The alternative, aforementioned method to
create a SiꢀSi bond, the insertion of a silylene into a
SiꢀH bond, proceeds extremely fast [7] and thus silanes
serve frequently as trapping agents for short-lived
silylenes [8]. Contrasting the wealth of silylene insertion
reactions into SiꢀH bonds, only few examples of a
insertion into SiꢀHal bonds are known [9]. We have
used both methods, i.e. silylene insertion and nucle-
ophilic displacement, for the synthesis of di- and trisi-
lanes, which bear the potentially chelating
2-(dimethylaminomethyl)phenyl substituent [9c,10], and
want to report here the results of these studies.
Scheme 1. Formation of SiꢀSi bond; M=Li, Na, MgHal; X=H,
Hal.
* Corresponding author. Tel.: +49-221-7490816.
E-mail address: jbelzne@gwdg.de (J. Belzner).
1 Present address: Henkelstr. 282, D-40599 Du¨sseldorf, Germany.
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01451-6

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J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
Table 1
Synthesis of disilanes by silylene insertion; Ar=2-(Me2NCH2)C6H4; Mes=2,4,6-Me3C6H2
Entry
Silylene precursor
Silane
Disilane(s)
Yield (%)
1
2
3
1
1
1
Me3SiCl (5)
Me2SiCl2 (7a)
Me2SiHCl (7b)
ClAr2SiꢀSiMe3 (6a)
54
95
78
ClAr2SiꢀSiMe2Cl (8a)
Har2SiꢀSiMe2Cl (8b)
ClAr2SiꢀSiMe2H (8c) a
HAr2SiꢀSiPh2H (10a)
ClAr2SiꢀSiPh2Cl (10b)
HAr2SiꢀSiPh2Cl (10c)
ClAr2SiꢀSiPh2H (10d) b
ClAr2SiꢀSi(4-MeC6H4)2Cl (12a)
ClAr2SiꢀSi(4-ClC6H4)2Cl (14a)
ClAr2SiꢀSi(2-EtC6H4)2Cl (16)
HAr2SiꢀSiAr2H [12] (18a)
ClAr2SiꢀSiAr2Cl (18b)
HAr2SiꢀSiAr2Cl (18c)
20
4
5
6
1
1
1
Ph2SiH2 (9a)
Ph2SiCl2 (9b)
Ph2SiHCl (9c)
78
78
83
7
8
9
1
1
1
1
1
1
1
1
1
3
3
3
3
1
(4-MeC6H4)2SiCl2 (11)
(4-ClC6H4)2SiCl2 (13)
(2-EtC6H4)2SiCl2 (15)
Ar2SiH2 (17a)
Ar2SiCl2 (17b)
Ar2SiHCl (17c)
19
44
40
88
96
68
97
75
98
85
80
38
35
82
traces
10
11
12
13
14
15
16
17
18
19
20
21
22
PhSiCl3 (23)
Ph2SiCl2 (9b)
Ar(Mes)SiCl2 (27b)
21
MesSiCl3 (30)
Mes2SiH2 (32a)
ClAr2SiꢀSiPhCl2 (24a)
ClAr(Mes)SiꢀSiPh2Cl (26b)
ClAr(Mes)SiꢀSiAr(Mes)Cl (28b)
29
ClAr(Mes)SiꢀSiMesCl2 (31)
HAr2SiꢀSiMes2H (33a)
a 8b:8c=3:1.
b 10c:10d=2:1.
2. Results and Discussion
and 22 could be synthesized by insertion of silylene 2
into a SiꢀCl bond of dichlorosiloles 19 or 21 (entries 13
and 14; Scheme 3). Using trichlorosilane 23 as substrate
clean formation of trichlorodisilane 24a was observed
(entry 15). However, reaction of 1 with highly coordi-
nated trichlorosilane ArSiCl3 (Ar=2-(Me2NCH2)C6H4;
25) did not give the corresponding trichlorodisilane.
Instead, dichlorosilane 17b was obtained quantitatively
besides a solid, which is insoluble in all common
solvents.
The reactions of thermally more stable cyclotrisilane
3 with silanes are less well investigated. However, treat-
ment of 3 with three equivalents of dichlorosilanes 9b,
27b, or 21 at temperatures between 80 and 90 °C
allowed the synthesis of the corresponding 1,2-dichloro-
disilanes 26b, 28b [9c], or 29 (entries 16–18). With
2.1. Formation of disilanes by silylene insertion
The insertion reactions of silylenes into SiꢀH and
SiꢀCl bonds of a variety of silanes were investigated
(Table 1) making extensive use of cyclotrisilanes 1 and
3 as thermal precursors of silylenes 2 and 4 (Scheme 2)
[9c,11]. When
1
was heated at 50 °C with
trimethylchlorosilane (5) in benzene, chlorodisilane 6a
was formed quantitatively and could be isolated in 54%
yield (entry 1). Using dimethyldichlorosilane (7a) as
starting material, the vicinally dihalogenated disilane 8a
was obtained as sole product; no formation of a trisi-
lane was observed, i.e. no subsequent insertion of
silylene 2 into a SiꢀCl bond of initially formed 8a did
occur under the reaction conditions employed (entry 2).
With dimethylmonochlorosilane (7b) as trapping agent,
a 3:1 mixture of regioisomeres 8b and 8c was formed
indicating that silylene 2 inserts preferentially into the
SiꢀH bond of the chlorosilane (entry 3). The reaction of
cyclotrisilane 1 with diphenylsubstituted silanes 9a–c
proceeded analogously (Table 1, entries 4, 5, 6), again
the insertion of silylene 2 in the SiꢀH bond of Ph2SiHCl
(9c) being preferred to that into the SiꢀCl bond. When
treating 1 with diarylsilanes 11, 13, 15, and 17a–c, in
which the aromatic rings bear a para- or ortho-sub-
stituent, the corresponding disilanes 12a, 14a, 16, 18a
[12], 18b, and 18c were obtained in reasonable to good
yields (entries 7–12). Similarly, 1,2-dichlorodisilanes 20
Scheme 2. Cyclotrisilanes as silylene precursors; Ar=2-
(Me2NCH2)C6H4; Mes=2,4,6-Me3C6H2.

J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
27
some starting material 32b as well as minor amounts of
dichlorosilane 17b and dichlorodisilane 18b. Using ster-
ically less demanding dimesitylsilane (32a) as substrate
was not successful either, only traces of the expected
insertion product 33a could be identified by means of
1H-NMR spectroscopy in the reaction mixture. At-
tempts to synthesize 1,2-dichlorodisilane 34b, either by
treatment of 1 with three equivalents of 27b or alterna-
tively by treatment of 3 with three equivalents of 17b,
failed (Scheme 4, bottom). In both cases, the respective
cyclotrisilane was totally consumed under formation of
a complex product mixture consisting of 1,2-dichloro-
disilane 18b as major product besides minor amounts of
dichlorosilanes 27b and 17b as well as various uniden-
tified compounds. Similarly, reaction of cyclotrisilane 1
with silane 27a or, alternatively, of 3 with silane 17a did
not yield disilane 34a.
Scheme 3. Reaction of 1 with dichlorosiloles; Ar=2-(Me2NCH2)-
C6H4.
2.2. Formation of trisilanes by silylene insertion
It was shown (vide supra) that reaction of cyclotrisi-
lanes 1 or 3 with different monosilanes gives exclusively
disilanes. Competing formation of trisilanes, which in
principle could arise from insertion of the silylene into
a SiꢀH or SiꢀCl bond of the newly formed disilane, was
never observed under the reaction conditions employed.
This selectivity implies that the reaction of the silylenes
2 and 4 with monosilanes is appreciably faster than that
with disilanes. However, the synthesis of trisilanes from
disilanes and cyclotrisilanes 1 or 3 as silylene precursors
proved to be possible using the appropriate stoichiome-
try of starting materials and, in most cases, performing
the reaction at higher temperatures (Table 2). Thus, e.g.
treatment of cyclotrisilane 1 with three equivalents of
disilane 35 yielded trisilane 36 (entry 1). With an excess
of 1 no further insertion of a silylene under formation
of a tetrasilane occurred, even under forcing reaction
conditions. Reaction of 1 with three equivalents of
unsymmetrical disilane 10a delivered trisilane 37a in
good yield (entry 2). Interestingly, the silylene inserts
regioselectively into the SiꢀH bond of the phenyl substi-
tuted silicon center of 10b. The reaction of 1 with three
equivalents of 1,2-dichlorodisilane 10b proceeds
analogously, giving exclusively the symmetrical 1,3-
dichlorotrisilane 37b, which also may be obtained di-
rectly from monosilane 9b and 1 employing a 3:2 ratio
of the reactants (entry 3). The observed regioselectivity
Scheme 4. Failed syntheses of disilanes; 17a, 27a, 32a, 33a, 34a:
X=H; 17b, 27b, 32b, 33b, 34b: X=Cl; Ar=2-(Me2NCH2)C6H4;
Mes=2,4,6-Me3C6H2.
trichlorosilane 30 as starting material, the insertion
product 31 was obtained in good yield (entry 19).
Albeit the reaction of cyclotrisilanes 1 and 3 with
monosilanes has proven to be a quite generally applica-
ble procedure for the synthesis of disilanes, some at-
tempts to obtain disilanes by this method were without
success: Thus, e.g., reaction of 1 with bulkily substi-
tuted dimesityldichlorosilane (32b) did not yield the
corresponding 1,2-dichlorodisilane 33b (Scheme 4, top).
Instead, a complex product mixture was formed which
contained, besides a variety of unidentified compounds,
Table 2
Synthesis of trisilanes by silylene insertion; Ar=2-(Me2NCH2)C6H4; Mes=2,4,6-Me3C6H2
Entry
Silylene precursor
Disilane
Trisilane
Yield (%)
1
2
3
1
1
1
ClPh2SiꢀSiPh2Cl (35)
HAr2SiꢀSiPh2H (10a)
ClAr2SiꢀSiPh2Cl (10b)
ClPh2SiꢀSiPh2ꢀSiAr2Cl (36)
HAr2SiꢀSiPh2ꢀSiAr2H (37a)
ClAr2SiꢀSiPh2ꢀSiAr2Cl (37b)
35
89
78

28
J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
Table 3
Synthesis of di- and trisilanes by nucleophilic substitution; Ar=2-(Me2NCH2)C6H4; Mes=2,4,6-Me3C6H2
Entry
Precursor of metallated silane
Metal
Halosilane
Product
Yield (%)
1
2
3
4
5
6
Ar2SiHCl (17c)
17c
HAr2SiSiAr2H (18a)
18a
K
K
Li
Li
Li
Li
Ar2SiHCl (17c)
Me3SiCl (5)
Me3SiCl (5)
Mes2SiCl2 (32b)
Me2SiCl2 (7a)
ArMesSiCl2 (27b)
HAr2SiꢀSiAr2H (18a)
HAr2SiꢀSiMe3 (6b)
6b
HAr2SiꢀSiMes2Cl (33c)
HAr2SiꢀSiMe2ꢀSiAr2H (38)
HMes2SiꢀSiAr(Mes)Cl (39a)
91
49
63
75
43
13
18a
Mes2SiHCl (32c)
Table 4
Transformation of disilanes; Ar=2-(Me2NCH2)C6H4; Mes=2,4,6-Me3C6H2
Entry
Disilane(s)
Reagent
Product
Yield (%)
1
2
ClAr2SiꢀSiMe3 (6a)
HAr2SiꢀSiMe2Cl (8b)
LiAlH4
LiAlH4
HAr2SiꢀSiMe3 (6b)
HAr2SiꢀSiMe2H (8d)
51
47
ClAr2SiꢀSiMe2H (8c)
3
HAr2SiꢀSiPh2Cl (10c)
ClAr2SiꢀSiPh2H (10d)
ClAr2SiꢀSi(4-MeC6H4)2Cl (12a)
ClAr2SiꢀSi(4-ClC6H4)2Cl (14a)
ClAr2SiꢀSiPhCl2 (24a)
HAr2SiꢀSiMes2Cl (33c)
HMes2SiꢀSiAr(Mes)Cl (39a)
HAr2SiꢀSiAr2H (18a)
LiAlH4
HAr2SiꢀSiPh2H (10a)
96
4
5
6
7
8
9
10
11
LiAlH4
LiAlH4
LiAlH4
LiAlH4
LiAlH4
NCS a
NCS b
NCS
HAr2SiꢀSi(4-MeC6H4)2H (12b)
HAr2SiꢀSi(4-ClC6H4)2H (14b)
HAr2SiꢀSiPhH2 (24b)
HAr2SiꢀSiMes2H (33a)
HMes2SiꢀSiArMesH (39b)
ClAr2SiꢀSiAr2Cl (18b)
91
65
41
65
47
72
59
77
HAr2SiꢀSiAr2H (18a)
HAr2SiꢀSiMes2Cl (33c)
HAr2SiꢀSiAr2Cl (18c)
ClAr2SiꢀSiMes2Cl (33b)
a Two equivalents NCS, solvent: CCl4.
b One equivalent NCS, solvent: hexane.
indicates that insertion of silylene 2 at a silicon center,
which bears ortho-substituted aryl groups, is sterically
hindered. In accordance with this conclusion, 1 reacts
neither with 16 nor with 18b or ClMes2SiꢀSiAr2Cl (33b)
under formation of trisilanes.
reacted with 5 (entry 3). Similarly, disilane 33c was
obtained from Ar2SiHLi and dichlorosilane 32b (entry
4). Using sterically less hindered 7a as electrophile the
reaction could not be stopped after the first substitution
step and therefore only trisilane 38 was isolated from
the reaction mixture (entry 5). Finally, bulkily substi-
tuted disilane 39a was synthesized by treatment of
preformed Mes2SiHLi with dichlorosilane 27b (entry 6).
2.3. Formation of disilanes by nucleophilic substitution
Nucleophilic coupling of a halosilane with a meta-
lated silane, which is easily prepared by reaction of a
halosilane or a disilane with alkali metals, is an alterna-
tive procedure for the synthesis of disilanes [13]. Thus,
disilane 18a is not only available by insertion of silylene
2 into the SiꢀH bond of silane 17a (vide supra), but also
can be obtained in good yield by reaction of chlorosi-
lane 17c with potassium in toluene via a potassio silane
Ar2SiHK as intermediate (Table 3, entry 1). This reac-
tion could not be performed using more easily manage-
able lithium in THF or toluene as under these
conditions cleavage of the SiꢀC bond of the starting
material occurred. Interestingly, treatment of a mixture
of chlorosilanes 17c and 5 with potassium resulted in
the formation of the unsymmetrical cross-coupling
product 6b (entry 2). A better yield of this disilane was
obtained when employing lithium in order to transform
disilane 18a into Ar2SiHLi, which subsequently was
2.4. Transformations of disilanes
Various halogen substituted disilanes (Table 4) can
easily be reduced to the corresponding hydrido disilanes
using LiAlH4 in Et2O. However, silole based dichloro-
disilanes 20 and 22 undergo cleavage of the SiꢀSi bond
under these reaction conditions.
N-Chlorosuccinimide (NCS) has proven in several
cases to be a superior reagent for chlorination of disi-
lanes [1a,5b]. Thus, 18a could be chlorinated at both
silicon centers by means of two equivalents of NCS in
CCl4. When performing the reaction in hexane as sol-
vent, the monochlorinated product 18c could be iso-
lated as main product. Dichlorodisilane 33b, which
could not be obtained by insertion of silylene 2 into the
SiꢀCl bond of dichlorosilane 32b (vide supra) and
which might be a useful precursor for a chelated disi-

J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
29
lene, was synthesized by treatment of 33c with NCS in
CCl4.
silylene 2 and not diphenylsilylene was generated. A
similar reactivity, i.e. extrusion of a coordinated
silylene, was reported for the thermal and/or metal-cat-
alyzed decomposition of disilanes bearing the 8-
dimethylamino-naphth-l-yl substituent [14].
2.5. Thermal stability of tri- and disilanes
1,2-Dichlorodisilanes are thermally more stable: 35
or 1,2-dichloro-1,1,2,2-tetramesityldisilane (42), which
bear no potentially chelating 2-(dimethylamino-
methyl)phenyl substituent, do not extrude silylenes
when heated to 110 °C for 15 h in the presence of a
silylene trap. In contrast, highly coordinated dichloro-
disilane 10b transfers silylene 2 to 40 under these condi-
tions; however, due to the relatively high temperatures,
minor amounts of by-products with unknown structure
are formed in this case. 1,2-Dichlorodisilane 18b re-
mains unchanged when treated with diene 40 at 70 °C
for 19 h (Scheme 6, top). However, when 18b was
treated under almost identical conditions, the only vari-
ation being the presence of a catalytic amount of
cyclotrisilane 1, the 1,2-dichlorodisilane was totally
consumed and a 1:1 mixture of 17b and 41 was formed
(Scheme 6, bottom). 28b (used as a mixture of the d,l-
and meso-diastereomers) shows a similar behavior. Nei-
ther silylene transfer to 40 nor change of the
diastereomeric ratio, which might result from extrusion
and re-insertion of silylene 2, were observed after 24 h
at 90 °C in the presence of excess 40. But 28b under-
went in the presence of 40 and a trace of 3 clean
conversion into a roughly equimolar mixture of 27b
and the corresponding silacyclopentene [15], which re-
sults from the transfer of silylene 4 to the diene. From
these observations it can be concluded that cyclotrisi-
lanes 1 and 3, i.e. the silylenes in equilibrium with these
cyclotrisilanes, catalyze the extrusion of silylene 2 or 4
from the respective 1,2-dichlorodisilane. Scheme 7
shows a possible mechanism for this reaction. The first
step is a dehalogenation of 18b by 2 under formation of
17b and disilene 43. Such kind of reduction of a 1,2-
dichlorodisilane by a silylene yielding a disilene is, to
the best of our knowledge, not known [16]. Jutzi,
however, has shown that silicocene reduces 1,2-dibro-
mocyclohexane to cyclohexene, thereby being trans-
formed itself into the corresponding dibromosilane [17],
and we have found that 2 reacts analogously with
1,2-dihaloethanes under formation of a olefin and 17b
[18]. Disilene 43 is assumed to be in equilibrium with
silylenes 2 [11,19], which can either be trapped irre-
versibly by diene 40 or can re-enter into the catalytic
cycle and reduce a further molecule of 18b. The effi-
ciency of the mechanism presented here depends cru-
cially on a delicate balance of the different steps
involved in the overall reaction. Thus, e.g. the dehalo-
genation of 18b by 2 needs to be faster than the
reaction of the silylene with 40 or its insertion into a
SiꢀCl bond of 18b. When, as in the case of 10b, silylene
2 inserts faster into the SiꢀCl bond under formation of
When 1,3-dichlorotrisilane 36 was heated in benzene
in the presence of excess 2,3-dimethylbuta-1,3-diene
(40) to 110 °C for 13 h quantitative conversion into a
1:1 mixture of 35 and silylene trapping product 41
occurred (Scheme 5, top). 1,3-Dichlorotrisilane 37b un-
derwent an analogous silylene extrusion under similar
conditions (Scheme 5, bottom): With 1,3-diene 40 as
trapping agent equimolar amounts of silacyclopentene
41 and dichlorodisilane 10b were formed, whereas ther-
mal silylene extrusion in the presence of one equivalent
of dichlorosilane 9b resulted in the clean formation of
two equivalents of dichlorodisilane 10b. It is worth
noting that in all these reactions exclusively the
chelated and therefore thermodynamically more stable
Scheme 5. Thermal silylene extrusion from trisilanes; Ar=2-
(Me2NCH2)C6H4.
Scheme 6. Silylene extrusion from 18b; Ar=2-(Me2NCH2)C6H4.
Scheme 7. Mechanism of the silylene-catalyzed reaction of 18b with
40; Ar=2-(Me2NCH2)C6H4.

30
J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
Table 5
introducing substituents into the para-position of the
phenyl rings of the adjacent SiPh2Cl group. Dichloro-
disilanes 12a and 14a absorb at similar frequencies as
10b. However, when the neighboring silicon center
bears ortho-substituted aryl groups as in 16 or 18b, the
coordination breaks down, presumably due to steric
hindrance. Accordingly, the silicon center of the
ClAr(Mes)Si group of 26b appears to be chelated,
because it is significantly highfield shifted as compared
with 35 or ClMes2SiꢀSiMes2Cl (42). In contrast, the
2-(dimethylaminomethyl)phenyl substituted silicon cen-
ter of chlorinated disilanes 28b, 31 and 39a, in all of
which the neighboring silicon center bears substituents,
which are sterically more demanding in comparison to
the phenyl groups of 26b, is not coordinated by the
amino group as is evident from the small shift differ-
ences in regard to the reference compounds 35 or 42.
Not only the chemical shifts of the silicon centers, but
also the different sensitivity of their resonance frequen-
cies towards temperature changes allow a discrimina-
tion of chelated and non-chelated silicon. The position
of the 29Si-NMR signal of the phenyl substituted silicon
center of 10b remains virtually constant upon tempera-
ture changes, whereas the resonance frequency of the
coordinated silicon moves from l= −29.7 at 280 K to
l= −20.6 at 320 K (Fig. 1a). This shift indicates that
chelated and non-chelated 10b is in equilibrium, the
non chelated form being favored at higher temperature
[21]. In contrast, the chemical shift of both silicon
centers of 33b remains essentially unchanged over a
temperature interval of 40 K (Fig. 1b) and thus sup-
29Si-NMR data of chlorinated disilanes Ar=2-(Me2NCH2)C6H4;
Mes=2,4,6-Me3C6H2
Disilane
l (Si 1)
l (Si 2)
ClPh2SiꢀSiPh2Cl (35) [31b]
ClMes2SiꢀSiMes2Cl (42) [1a]
ClAr2SiꢀSiPh2Cl (10b)
ClAr2SiꢀSi(4-MeC6H4)2Cl (12a)
ClAr2SiꢀSi(4-ClC6H4)2Cl (14a)
ClAr2SiꢀSi(2-EtC6H4)2Cl (16)
ClAr2SiꢀSiAr2Cl (18b)
ClAr(Mes)SiꢀSiPh2Cl (26b)
ClAr(Mes)SiꢀSiAr(Mes)Cl (28b)
ClAr(Mes)SiꢀSiMesCl2 (31)
ClAr(Mes)SiꢀSiMes2H (39a)
ClAr2SiꢀSiMes2Cl (33b)
−6.1
+0.2
−21.7
−19.6
−24.3
−4.5
−2.9
−15.0
−2.6
−6.1
+0.2
−2.3
−1.8
−3.4
+0.4
−2.9
−2.1
−2.6
9.4
−9.0
+1.5
−51.4
−4.8 a
+0.2 a
a The assignment is ambiguous.
37b (vide supra) as it reduces 10b to the corresponding
disilene, an auto-catalyzed extrusion of silylenes 2 is
impossible.
2.6. Structures in the solid state and in solution
Several 1,2-dichlorotetraaryldisilanes were investi-
gated in regard to the ability of the 2-(dimethy-
laminomethyl)phenyl
substituent
to
coordinate
intramolecularly to the silicon center (Table 5). If coor-
dination occurs in solution, the chelated silicon center is
expected to resonate at higher field in comparison to
the silicon nucleus of an appropriate reference com-
pound, in which the silicon center is non-coordinated
[20]. The 29Si-NMR signal of dichlorodisilane 10b, e.g.
is shifted significantly to higher field in comparison to
ClPh2SiꢀSiPh2Cl (35) indicating that there is a coordi-
native interaction between the amino group of the
2-(dimethylaminomethyl)phenyl substituent and the sili-
con center. This coordination is hardly affected by
ports
the
conclusion
that
the
2-(dimethy-
laminomethyl)phenyl substituted center of 33b is not
chelated by the amino group.
Chlorosilane 39a adopts in the solid state a staggered
conformation (Fig. 2), which already was reported for
other tetraaryl disilanes [5b,22]. The Si(1)ꢀN(1) distance
,
(3.312(2) A) is shorter than the sum of the van der
Fig. 1. 29Si-NMR spectra of 10b and 33b at variable temperature; Ar=2(Me2NCH2)C6H4;(a) Spectra of 10b at 320 K (top) and 280 K (bottom);
(b) Spectra of 33b at 340 K (top) and 300 K (bottom).

J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
31
,
Waals-radii of both elements (3.6 A) [23], but apprecia-
bly longer than that of dative Si“N bonds (ca. 1.8–3.0
,
an ortho-nitrophenyl octyl ether (NOE) or meta-ni-
trobenzylalcohol (3-NBA) matrix. Elemental analyses
were performed at Mikroanalytisches Labor der Georg-
August-Universita¨t Go¨ttingen [26].
All manipulations of air and moisture sensitive com-
pounds were carried out under an inert argon atmo-
sphere using carefully dried glassware. Ethereal
solvents, hexane, pentane, toluene and C6D6 used were
dried by refluxing over sodium benzophenone ketyl and
distilled immediately before use; CDCl3, CCl4 was dried
A) [24]. Thus, there is apparently no significant coordi-
native interaction between Si(1) and N(1) in the solid
state as it was found for the structure of 39a in solu-
tion. This conclusion is corroborated by the fact that
the lone pair of the amino nitrogen is not directed
exactly towards the silicon center. Instead, the vector
[25] of the lone pair forms an angle of 31.8° with the
line which joins Si(1) and N(1).
,
using molecular sieve (4 A). Mes2SiHLi [27], 19 [28], 21
[3a], 32b [29], 32c [30], and 35 [31] were obtained by
3. Experimental
published procedures.
1H- and13C-NMR spectra were recorded on a Bruker
AM 250 (1H-NMR, 250 MHz, 13C-NMR, 62.9 MHz), a
Bruker AMX 300 (1H-NMR: 300 MHz, 13C-NMR:
75.5 MHz) and a Varian VXR 500 (1H-NMR, 500
MHz,13C-NMR, 125.7 MHz). Cq, CH, CH2 and CH3
were determined using the DEPT or APT pulse se-
quence. 29Si-NMR spectra were recorded on a Bruker
AMX 300 (59.6 MHz) or a Varian XL 500 (99.3 MHz)
using a refocused INEPT pulse sequence or performing
a direct acquisition. Chemical shifts refer to lTMS=0.0.
IR spectra were recorded on a Bruker IFS 66 (film or
KBr). Mass spectra were recorded on a Varian MAT
311 A. High resolution mass spectra were determined
with a Varian MAT 311 A, using preselected ion peak
matching at Rꢀ10 000 to be within 92 ppm of the
exact mass. FAB mass spectra were obtained by using
3.1. Formation of disilanes by silylene insertion
3.1.1. 1-Chloro-1,1-bis[2-(dimethylaminomethyl)-
phenyl]-2,2,2-trimethyldisilane (6a)
A solution of 120 mg (0.14 mmol) of 1 and 51 ml
(0.40 mmol) of 5 in 0.5 ml of C6D6 was heated at
50 °C. After 4 h only 6a and surplus 5 could be
1
detected in the reaction mixture by means of H-NMR
spectroscopy. The solvent was removed in vacuo, 5 ml
of hexane were added and the resulting suspension was
filtered leaving behind 87 mg (54%) of 6a as a white
solid (melting point (m.p.) 92–93 °C). 1H-NMR
(C6D6): l=0.36 (s, 9H, SiMe3), 1.78 (s, 12H, NMe2),
2.99, 3.42 (AB system, 2JAB=13 Hz, 4H, CH2N), 7.13–
3
4
7.24 (m, 4H, ar H), 7.38 (dd, J=8 Hz, J=2 Hz, 2H,
ar H), 8.07 (dd, J=6 Hz,4J=2 Hz, 2H, ar H). 13C-
3
NMR (C6D6): l= −0.3 (SiMe3), 45.3 (NMe2), 64.2
(CH2N), 126.6 (ar CH), 128.7 (ar CH), 129.9 (ar CH),
135.6 (ar Cq), 136.6 (ar CH), 146.0 (ar Cq). 29Si-NMR
(C6D6): l= −1.2 (SiCl)), −13.3 (SiMe3).
3.1.2. 1,2-Dichloro-1,1-bis[2-(dimethylaminomethyl)-
phenyl]-2,2-dimethyldisilane (8a)
A solution of 118 mg (0.13 mmol) of 1 and 48 ml
(0.40 mmol) of 7a in 0.5 ml of C6D6 was heated for 2.5
h at 55 °C. After removal of the solvent and excess
silane in vacuo 161 mg (95%) of 8a were obtained as a
1H-NMR spectroscopically pure, colorless oil. 1H-
NMR (C6D6): l=0.75 (s, 6H, SiMe2), 1.86 (s, 12H,
NMe2), 3.00, 3.46 (AB system, 2JAB=13 Hz, 4H,
CH2N), 7.11–7.27 (m, 6H, ar H), 8.22–8.26 (m, 2H, ar
H). 13C-NMR (C6D6): l=4.5 (SiMe2), 45.5 (NMe2),
64.3 (CH2N), 126.9 (ar CH), 128.2 (ar CH), 130.1 (ar
CH), 135.3 (ar Cq), 136.9 (ar CH), 145.9 (ar Cq).
29Si-NMR (C6D6): l=16.2 (SiMe2Cl), −29.6
(SiAr2Cl). MS (EI), m/z (%): 424 (8) [M]+, 290 (92)
[M+ꢀAr], 134 (36) [Ar]+, 91 (75) [C7H7]+, 58 (45)
[CH2NMe2]+.
,
Fig. 2. X-ray structure of 39a; selected distances [A], bond angles and
torsion angles [°]: Si(1)ꢀN(1) 3.312(2), Si(1)ꢀSi(2) 2.3692(10),
Si(1)ꢀCl(1) 2.1066(9), Si(1)ꢀC(11) 1.887(2), Si(1)ꢀC(21) 1.891(2),
Si(2)ꢀH(1) 1.39, Si(2)ꢀC(31) 1.908(2), Si(2)ꢀC(41) 1.894(2); Cl(1)ꢀ
Si(1)ꢀC(11) 103.13(7), Cl(1)ꢀSi(1)ꢀSi(2) 102.56(3), Cl(1)ꢀSi(1)ꢀC(21)
104.63(7), C(11)ꢀSi(1)ꢀSi(2) 104.19(6), C(11)ꢀSi(1)ꢀC(21) 113.82(9),
C(21)ꢀSi(1)ꢀSi(2) 125.78(7); C(21)ꢀSi(1)ꢀSi(2)ꢀC(31) 172.24(10),
Cl(1)ꢀSi(1)ꢀSi(2)ꢀH(1) 163.8, C(11)ꢀSi(1)ꢀSi(2)ꢀC(41) 176.64(10).

32
J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
3.1.3. 2-Chloro-1,1-bis[2-(dimethylaminomethyl)-
phenyl]-2,2-dimethyldisilane (8b) and
Anal. Calc. for C30H36N2Si2 (480.80): C, 74.94; H 7.55.
Found: C, 75.40; H, 8.01%.
1-chloro-1,1-bis[2-(dimethylaminomethyl)phenyl]-2,2-
dimethyldisilane (8c)
3.1.5. 1,2-Dichloro-1,1-bis[2-(dimethylaminomethyl)-
phenyl]-2,2-diphenyldisilane (10b)
A solution of 140 mg (0.16 mmol) of 1 and 51 ml
(0.47 mmol) of 7b in 0.5 ml of C6D6 was heated for 2 h
at 70 °C. After removal of the solvent and surplus
silane in vacuo 154 mg (78%) of a 3:1 mixture of 8b and
A solution of 5.00 g (5.62 mmol) of 1 and 3.25 ml
(16.9 mmol) of 9b in 50 ml of toluene was stirred for 2
days at 55 °C. The solvent was removed in vacuo and
150 ml of pentane were added to the solid residue. The
resulting suspension was filtered and the filtrate was
reduced in vacuo to a volume of 40 ml. After cooling at
−20 °C for 15 h 7.77 g (78%) of 10b were obtained as
1
c were obtained as a viscous oil. 8b: H-NMR (C6D6):
l=0.55 (s, 6H, SiMe2), 1.82 (s, 12H, NMe2), 3.27 (s,
4H, CH2N), 5.22 (s (d, 1JSiH=202 Hz), 1H, SiH),
3
7.06–7.21 (m, 6H, ar H), 7.84 (d, J=6 Hz, 2H, ar H).
13C-NMR (C6D6): l=4.4 (SiMe2), 45.7 (NMe2), 65.0
(CH2N), 126.5 (ar CH), 129.1 (ar CH), 129.4 (ar CH),
134.2 (ar Cq), 137.5 (ar CH), 145.7 (ar Cq). 29Si-NMR
a colorless solid (m.p. 114–115 °C). H-NMR (C6D6):
1
2
l=1.82 (s, 12H, NMe2), 3.04, 3.42 (AB system, JAB
=
14 Hz, 4H, CH2N), 7.04–7.20 (m, 10H, ar H), 7.29 (d,
1
(C6D6): l=22.8 (SiMe2Cl), −41.1 (d, JSiH=202 Hz,
3J=8 Hz, 2H, ar H), 7.90–7.94 (m, 4H, ar H), 8.39
SiAr2H). IR (film): w˜ =2114 cm−1. 8c: 1H-NMR
(dd, J=7 Hz, 4J=2 Hz, 2H, ar H). 13C-NMR (C6D6):
3
(C6D6): l=0.36 (d, 3J=4 Hz, 6H, SiMe2), 1.79 (s,
l=45.4 (NMe2), 64.0 (CH2N), 126.5 (ar CH), 127.9 (ar
CH), 128.3 (ar CH), 130.2 (ar CH), 130.3 (ar CH),
134.0 (ar Cq), 134.8 (ar Cq), 135.8 (ar CH), 137.5 (ar
CH), 146.0 (ar Cq). 29Si-NMR (C6D6): l= −2.3 (Si 2),
−21.7 (Si 1). MS (EI, 70 eV), m/z (%): 552/550/548
(1/3/4) [M]+, 418/416/414 (11/41/55) [M+ꢀAr], 333/331
2
12H, NMe2), 3.05, 3.39 (AB System, JAB=14 Hz, 4H,
3
1
CH2N), 4.26 (sep, J=4 Hz (d, JSiH=182 Hz), 1H,
3
SiH), 7.06–7.21 (m, 4H, ar H), 7.28 (d, J=7 Hz, 2H,
ar H), 8.10 (dd, 3J=6 Hz, 4J=2 Hz, 2H, ar H).
13C-NMR (C6D6): l= −5.0 (SiMe2), 45.2 (NMe2),
64.1 (CH2N), 126.7 (ar CH), 128.1 (ar CH), 129.7 (ar
CH), 135.7 (ar Cq), 136.8 (ar CH), 145.5 (ar Cq).
29Si-NMR (C6D6): l= −16.8 (SiAr2Cl) l= −35.0
(dsep, 1JSiH=182, 2JSiH=7 Hz, SiMe2H). IR (film):
(18/44)
[M+ꢀPh2SiCl],
288/286
(20/35)
[M+
ꢀPh2SiClꢀHNMe2], 274/272 (18/47) [M+ꢀPh2SiClꢀ
NMe2ꢀMe], 200/198 (14/39) [M+ꢀPh2SiClꢀAr+H],
134 (18) [Ar]+, 91 (19) [C7H7]+, 77 (21) [C6H5]+, 58
(49) [CH2NMe2]+. C30H34N2Si2Cl2 (548.1637): correct
HRMS. Anal. Calc. for C30H34N2Si2Cl2 (549.69): C,
65.55; H, 6.23. Found: C, 66.01; H, 6.66%.
w˜ =2114 cm−1
.
3.1.4. 1,1-Bis[2-(dimethylaminomethyl)phenyl]-
2,2-diphenyldisilane (10a)
A solution of 148 mg (0.17 mmol) of 1 and 93 ml
(0.50 mmol) of 9a in 2 ml of toluene was heated for 2
h at 90 °C. After removal of the solvent in vacuo 188
3.1.6. 2-Chloro-1,1-bis[2-(dimethylaminomethyl)-
phenyl]-2,2-diphenyldisilane (10c) and
1-chloro1,1-bis[2-(dimethylaminomethyl)phenyl]-2,2-
diphenyldisilane (10d)
1
mg (78%) of 10a were obtained as a viscous oil. H-
A solution of 123 mg (0.14 mmol) of 1 and 81 ml
(0.42 mmol) of 9c in 0.5 ml of C6D6 was stirred for 20
min at 90 °C. After removal of the solvent in vacuo
178 mg (83%) of a 2:1 mixture of 10c and 10d were
NMR (C6D6): l=1.83 (s, 12H, NMe2), 3.31 (s, 4H,
CH2N), 5.45 (d, 3J=3 Hz (d, 1JSiH=189 Hz), 1H,
3
1
SiH), 5.61 (d, J=3 Hz (d, JSiH=200 Hz), 1H, SiH),
3
3
3
4
1
6.99 (ddd, J=7 Hz, J=7 Hz, J=7 Hz, J=1 Hz,
2H, ar H) 7.08–7.22 (m, 10H, ar H), 7.64–7.68 (m, 4H,
obtained as a viscous oil. 10c: H-NMR (C6D6): l=
2
1.77 (s, 12H, NMe2), 3.18, 3.38 (AB system, JAB=13
3
1
ar H), 7.77 (d, J=7 Hz, 2H, ar H). 13C-NMR (C6D6):
Hz, 4H, CH2N), 5.72 (s (d, JSiH=209 Hz), 1H, SiH),
l=44.7 (NMe2), 65.0 (CH2N), 126.5 (ar CH), 128.2 (ar
CH), 129.1 (ar CH), 129.1 (ar CH), 129.1 (ar CH),
135.1 (ar Cq), 135.5 (ar Cq), 136.5 (ar CH), 138.1 (ar
CH), 146.0 (at Cq). 29Si-NMR (C6D6): l= −30.8
(ddqin, 1JSiH=189 Hz, 2JSiH=5 Hz, 3JSiH=4 Hz,
SiPh2H), −42.3 (ddt, 1JSiH=200 Hz, 2JSiH=5 Hz,
3JSiH=6 Hz, SiAr2H). IR (film): w˜ =2128 cm−1. MS
(EI, 70 eV), m/z (%): 479 (1) [M+ꢀH], 435 (8) [M+
ꢀNMe2ꢀH], 420 (12) [M+ꢀNMe2ꢀMeꢀH], 346 (11) [M+
ꢀAr], 297 (100) [M+ꢀPh2SiH], 252 (10) [M+ꢀPh2-
SiHꢀNMe2ꢀH], 238 (13) [M+ꢀPh2SiHꢀNMe2ꢀMe], 209
(8) [M+ꢀPh2SiHꢀ2NMe2], 182 (8) [Ph2Si]+, 134 (2)
[Ar]+, 105 (13) [PhSi]+, 91 (3) [C7H7]+, 58 (10)
[CH2NMe2]+. C30H36N2Si2 (480.2417): correct HRMS.
6.93–7.28 (m, 12H, ar H), 7.68–7.71 (m, 4H, ar H),
3
7.82 (d, J=7 Hz, 2H, ar H). 13C-NMR (C6D6): l=
44.8 (NMe2), 64.8 (CH2N), 126.4 (ar CH), 128.2 (ar
CH), 128.9 (ar CH), 129.5 (ar CH), 130.0 (ar CH),
132.9 (ar Cq), 135.2 (ar CH), 136.7 (ar Cq), 138.2 (ar
CH), 146.1 (ar Cq). 29Si-NMR (C6D6): l=3.5
(Ph2SiCl), −31.9 (dt, 1JSiH=209 Hz, 3JSiH=6 Hz,
Ar2SiH). 10d: 1H-NMR (C6D6): l=1.80 (s, 12H,
NMe2), 3.13, 3.34 (AB system, 2JAB=13 Hz, 4H,
CH2N), 5.46 (s (d, 1JSiH=190 Hz), 1H, SiH), 6.93–7.28
(m, 12H, ar H), 7.84–7.87 (m, 4H, ar H), 8.22 (d, 3J=7
Hz, 2H, ar H). 13C-NMR (C6D6): l=45.4 (NMe2),
64.1 (CH2N), 126.6 (ar CH), 128.1 (ar CH), 128.9 (ar
CH), 129.6 (ar CH), 133.9 (ar Cq), 134.8 (ar CH), 135.3

J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
33
(ar Cq), 136.9 (ar CH), 137.5 (ar CH), 145.9 (ar Cq).
ꢀ(ClC6H4)2SiClꢀNMe2ꢀH], 178 (58) [C12H6Si]+, 134
(45) [Ar]+, 58 (53) [CH2NMe2]+. C30H32Cl4N2Si2
(616.0858): correct HRMS. Anal. Calc. for C30H32Cl4-
N2Si2 (618.58): C, 58.25; H, 5.21. Found: C, 59.19; H,
5.42%.
29Si-NMR (C6D6): l= −18.2 (Ar2SiCl), −45.2 (dqin,
3
1JSiH=189 Hz, JSiH=5 Hz, Ph2SiH).
3.1.7. 1,2-dichloro-1,1-bis[2-(dimethylaminomethyl)-
phenyl]-2,2-bis(4-methylphenyl)disilane (12a)
3.1.9. 1,2-Dichloro-2,2-bis(2-ethylphenyl)-1,1-
bis[2-(dimethylaminomethyl)phenyl]disilane (16)
A solution of 247 mg (0.28 mmol) of 1 and 234 mg
(0.83 mmol) of 11 in 8 ml of toluene was heated for 17
h at 50 °C. The solvent was removed in vacuo and 14
ml of Et2O were added to the solid residue. The result-
ing suspension was filtered, the filtrate was evaporated
in vacuo and the residue was dissolved in 10 ml of
pentane. The solution was cooled at −20 °C for 3
days and 214 mg (44%) of 12a were obtained as a
colorless solid (m.p. 105–107 °C). 1H-NMR (C6D6):
l=1.85 (s, 12H, NMe2), 1.95 (s, 6H, CH3), 3.04, 3.43
A solution of 1.00 g (1.12 mmol) of 1 and 1.04 g
(0.37 mmol) of 15 in 20 ml of toluene was heated for 8
h at 50 °C. The solvent was removed in vacuo, 50 ml of
pentane was added to the solid residue and the resulting
suspension was filtered. The solvent was evaporated in
vacuo from the filtrate leaving behind 1.79 g (88%) of
16 as 1H-NMR spectroscopically pure, yellowish oil.
3
1H-NMR (C6D6): l=0.94 (t, J=7 Hz, 6H, CH2CH3
6
),
3
2
3
1.87 (s, 12H, NMe2), 2.64 (q, J=7 Hz, 4H, CH2
6
CH3),
(AB system, JAB=14 Hz, 4H, CH2N), 6.93 (d, J=8
Hz, 4H, ar H), 7.12–7.20 (m, 4H, ar H), 7.28–7.32 (m,
2
3.19, 3.57 (AB System, JAB=14 Hz, 4H, CH2N), 6.92
3
3
3
(dd, Jꢁ3J=7 Hz, 2H, ar H), 6.95 (dd, Jꢁ3J=7 Hz,
2H, ar H), 7.89 (d, J=8 Hz, 4H, ar H), 8.44–8.48 (m,
3
2H, ar H), 7.05 (d, J=7 Hz, 2H, ar H), 7.05–7.30 (m,
2H, ar H). 13C-NMR (C6D6): l=21.4 (CH3), 45.5
(NMe2), 64.1 (CH2N), 126.6 (ar CH), 128.4 (ar CH),
129.0 (ar CH), 130.4 (ar CH), 131.6 (ar Cq), 134.4 (ar
Cq), 136.0 (ar CH), 137.7 (ar CH), 140.2 (ar Cq), 146.2
(ar Cq). 29Si-NMR (C6D6): l= −1.8 (Si 2), −19.6 (Si
1). MS (EI, 70 eV), m/z (%): 578/576 (2/3) [M]+,
508/506 (3/5) [M+ꢀNMe2ꢀMeꢀH], 446/444/442 (8/33/
48) [M+ꢀAr], 333/331 (19/57) [Ar2SiCl]+, 274/272 (35/
100) [M+ꢀ(MeC6H4)SiClꢀNMe2ꢀMe], 200/198 (31/100)
[ArSiClH]+, 178 (82) [C12H6Si]+, 91 (43) [C7H7]+, 58
(56) [CH2NMe2]+. C32H38Cl2N2Si2 (576.1950): correct
HRMS. Anal. Calc. for C32H38Cl2N2Si2 (577.74): C,
66.53; H, 6.63. Found: C, 67.26; H, 6.71%.
3
4H, ar H), 7.50 (d, J=8 Hz, 2H, ar H), 7.98–8.15 (m,
4H, ar H). 13C-NMR (C6D6): l=15.3 (CH2C
6
H3), 29.9
(C
6 H2CH3), 45.3 (NMe2), 64.0 (CH2N), 125.4 (ar CH),
126.4 (ar CH), 128.8 (ar CH), 128.9 (ar CH), 130.6 (ar
CH), 131.0 (ar CH), 133.0 (ar Cq), 133.1 (ar Cq), 137.0
(ar CH), 137.6 (ar CH), 146.6 (ar Cq), 151.0 (ar Cq).
29Si-NMR (C6D6): l= +0.4 (Si 2), −4.5 (Si 1). MS
(FAB, NOE), m/z (%): 603 (100) [M+−1].
3.1.10. 1,1,2,2-Tetrakis[2-(dimethylaminomethyl)-
phenyl]disilane [12] (18a)
110 mg (0.12 mmol) of 1 and 112 mg (0.38 mmol) of
17a were dissolved in 0.5 ml of C6D6 and heated for 3
days at 70 °C and additional 2 days at 90 °C. The
cloudy solution was filtered. Removing of the solvent
from the filtrate in vacuo left behind 223 mg (96%) of
18a as a colorless solid (m.p. 90–92 °C). 1H-NMR
(C6D6): l=1.91 (s, 24H, NMe2), 3.35, 3.57 (AB Sys-
3.1.8. 1,2-Dichloro-1,1-bis[2-(dimethylaminomethyl)-
phenyl]-2,2-bis(4-chlorophenyl)disilane (14a)
A solution of 300 mg (0.34 mmol) of 1 and 326 mg
(1.01 mmol) of 13 in 8 ml of toluene was heated for 17
h at 50 °C. The solvent was removed in vacuo and 20
ml of Et2O were added to the solid residue. The result-
ing suspension was filtered and the solvent was evapo-
rated from the filtrate in vacuo. The residue was solved
in 10 ml of pentane and the solution was cooled to
−20 °C. After 3 days, 249 mg (40%) of 14a were
2
1
tem, JAB=14 Hz, 8H, CH2N), 5.51 (s (dd, JSiH=200
3
3
Hz, JHH=2 Hz), 2H, SiH), 6.99 (ddd, Jꢁ3J=7 Hz,
4J=1 Hz, 4H, ar H), 7.16 (ddd, Jꢁ3J=7 Hz, J=1
3
4
3
Hz, 4H, ar H), 7.28 (d, J=7 Hz, 4H, ar H), 7.68 (dd,
3J=7 Hz, J=1 Hz, 4H, ar H). 13C-NMR (CDCl3):
4
l=44.9 (NMe2), 64.5 (CH2N), 125.8 (ar CH), 128.3 (ar
CH), 128.4 (ar CH), 136.1 (ar Cq), 137.6 (ar CH), 145.2
(ar C9). 13C-NMR (C6D6): l=45.0 (NMe2), 65.3
(CH2N), 126.3 (ar CH), 128.6 (ar CH), 128.9 (ar CH),
137.6 (ar Cq), 138.2 (ar CH), 145.7 (ar Cq). 29Si-NMR
(C6D6): l= −41.5. IR (KBr): w˜ =2140 cm−1. MS
(FAB, 3-NBA), m/z (%): 593 (1) [M+ꢀH], 297 (100)
[(M/2)]+. Anal. Calc. for C36H50N4Si2 (595.0): C, 72.67;
H, 8.47; N, 9.42. Found: C, 72.58; H, 8.53; N, 9.37%.
1
obtained as a colorless solid (m.p. 115–116 °C). H-
NMR (C6D6): l=1.81 (s, 12H, NMe2), 3.03, 3.40 (AB
2
3
system, JAB=14 Hz, 4H, CH2N), 7.04 (d, J=8 Hz,
3
4H, ar H), 7.09–7.31 (m, 6H, ar H), 7.65 (d, J=8 Hz,
3
4
4H, ar H), 8.28 (dd, J=7 Hz, J=2 Hz, 2H, ar H).
13C-NMR (C6D6): l=45.5 (NMe2), 64.1 (CH2N), 126.8
(ar CH), 128.4 (ar CH), 130.5 (ar CH), 133.2 (ar Cq),
134.0 (ar Cq), 135.6 (ar CH), 137.0 (ar Cq), 137.3 (ar
CH), 137.4 (ar CH), 145.9 (ar Cq). 29Si-NMR (C6D6):
l= −3.4 (Si 2), −24.3 (Si 1). MS (El, 70 eV), m/z
(%): 620/618/616 (5/8/6) [M]+, 585/583/581 (5/13/12)
[M+ꢀCl], 488/486/484/482 (17/50/82/57) [M+ꢀAr], 333/
331 (38/100) [Ar2SiCl]+, 288/286 (33/61) [M+
3.1.11. 1,2-Dichloro-1,1,2,2-tetrakis[2-(dimethylamino-
methyl)phenyl]disilane (18b)
A solution of 50 mg (56 mmol) of 1 and 62 mg (0.17
mmol) of 17b in 0.5 ml of C6D6 was heated for 4.5 h at

34
J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
50 °C. The solvent was removed in vacuo leaving be-
hind 102 mg (91%) of crude 18b, which was solved in 2
ml of hexane. On cooling the solution to −20 °C for 4
days, 77 mg (68%) of 18b were obtained as a white solid
1H-NMR (C6D6): l=1.80 (s, 24H, NMe2), 3.20, 3.46
CH), 128.2 (ar CH), 128.5 (ar CH), 130.4 (ar CH),
131.6 (ar CH), 134.0 (ar Cq), 134.3 (ar CH), 136.4 (ar
Cq), 137.4 (ar CH), 145.9 (ar Cq), 148.0 (ar Cq). 29Si-
NMR (C6D6): l= −1.0, −19.0.
2
3
(AB system, JAB=14 Hz, 8H, CH2N), 6.83 (dd, J=7
3.1.14. 1-Chloro-1-{bis[2%-(dimethylaminomethyl)-
phenyl]chlorosilyl}-2,3,4,5-tetraphenyl-1-silacyclo-
pentadiene (22)
3
3
3
Hz, J=7 Hz, 4H, ar H), 7.07 (ddd, J=7 Hz, J=7
Hz, 4J=1 Hz, 4H, ar H), 7.52 (d, 3J=7 Hz, 4H, ar H),
8.00 (d, J=7 Hz, 4H, ar H). 13C-NMR (C6D6): l=
3
A solution of 610 mg (1.34 mmol) of 21 and 400 mg
(0.45 mmol) of 1 in 10 ml of toluene was stirred for 4
h at 65 °C. The solvent was removed in vacuo leaving
behind 1.00 g (98%) of 22 as yellow crystals (m.p.
45.4 (NMe2), 63.9 (CH2N), 126.4 (ar CH), 128.9 (ar
CH), 130.7 (ar CH), 133.2 (ar Cq), 137.5 (ar CH), 146.8
(ar Cq). 29Si-NMR (C6D6): l= −2.9. MS (EI, 70 eV),
m/z (%): 662 (B1)) [M]+, 627 (10) [M+ꢀCl], 331 (85)
[(M/2)]+, 178 (100) [C12H6Si]+. Anal. Calc. for
C36H48Cl2N4Si2 (663.9): C, 65.13; H, 7.29; N, 8.44.
Found: C, 65.08; H, 7.61; N, 8.35%.
1
94–96 °C). H-NMR (C6D6): l=1.78 (s, 12H, NMe2),
2.92, 3.41 (AB System, 2JAB=13 Hz, CH2N, 4H),
6.72–6.87 (m, ar H, 12H), 6.95 (ddd, 3Jꢁ3J=7 Hz,
4J=1 Hz, 2H, ar H), 7.02–7.15 (m, 8H, ar H), 7.28
(dd, 3J=8 Hz, 4J=1 Hz, ar H, 4H), 8.23 (d, 3J=8 Hz,
2H, ar H). 13C-NMR (C6D6): l=45.5 (NMe2), 64.1
(CH2N), 126.1 (ar CH), 126.6 (ar CH), 126.8 (ar CH),
128.3 (ar CH), 128.5 (ar CH), 129.3 (ar CH), 130.1 (ar
CH), 130.2 (ar CH), 130.3 (ar CH), 134.2 (ar Cq), 138.0
(ar CH), 138.5 (ar Cq), 138.8 (ar Cq) 140.6 (ar Cq),
145.7 (ar Cq), 156.7 (ar Cq). 29Si-NMR (C6D6): l=0.6,
−26.4. MS (FAB (NOE), pos. mode), m/z (%): 753/
751 (1/2) [M+1]+, 715 (2) [M+ꢀCl, correct isotope
pattern].
3.1.12. 1-Chloro-1,1,2,2-tetrakis[2-(dimethylamino-
methyl)phenyl]disilane (18c)
A solution of 85 mg (96 mmol) of 1 and 95 mg (0.29
mmol) of 17c in 0.8 ml of C6D6 was heated for 6 h at
50 °C. The solvent was removed in vacuo leaving be-
hind 175 mg (97%) of 18c as a colorless solid (m.p.
1
80–82 °C). H-NMR (C6D6): l=1.83 (s, 12H, NMe2),
1.96 (s, 12H, NMe2), 3.31, 3.37 (AB system,2JAB=13
2
Hz, 4H, CH2N), 3.39, 3.60 (AB system, JAB=14 Hz,
1
4H, CH2N), 5.90 (s, (d, JSiH=201 Hz), 1H, SiH), 6.98
(dd, 3J=7 Hz, 3J=7 Hz, 2H, ar H), 7.05–7.23 (m, 6H,
3.1.15. 1,1-Bis[2-(dimethylaminomethyl)phenyl]-
2-phenyl-1,2,2-trichlorodisilane (24a)
3
3
ar H), 7.40 (d, J=7 Hz. 2H, ar H), 7.44 (d, J=7 Hz,
3
3
2H, ar H), 8.04 (d, J=8 Hz, 2H, ar H), 8.28 (d, J=8
Hz, 2H, ar H). 13C-NMR (C6D6): l=45.0 (NMe2),
45.1 (NMe2), 64.1 (CH2N), 64.8 (CH2N), 126.2 (ar
CH), 126.4 (ar CH), 128.3 (ar CH), 128.8 (ar CH),
129.4 (ar CH), 129.9 (ar CH), 133.9 (ar Cq), 137.0 (ar
Cq), 137.7 (ar CH), 138.8 (ar CH), 145.7 (ar Cq), 146.3
(ar Cq). 29Si-NMR (C6D6): l= −44.8 (Si 2), −8.6 (Si
1). Anal. Calc. for C36H49ClN4Si2 (629.4): C, 68.70; H,
7.85; N, 8.90. Found: C, 68.57; H, 7.90; N, 8.82%.
A solution of 527 mg (0.60 mmol) of 1 and 284 ml
(1.78 mmol) in 10 ml of toluene was stirred for 7 days
at room temperature (r.t.). After removing the solvent
in vacuo 10 ml of hexane were added to the residue and
the resulting suspension was filtered. The solvent was
removed from the filtrate in vacuo leaving behind 768
mg (85%) of 24a as a viscous oil. 1H-NMR (C6D6):
2
l=1.78 (s, 12H, NMe2), 2.90, 3.43 (AB system, JAB
=
13 Hz, 4H, CH2N), 6.97–7.16 (m, 9H, ar H), 7.89–7.97
(m, 2H, ar H), 8.29–8.33 (m, 2H, ar H). 13C-NMR
(C6D6): l=45.5 (NMe2), 64.3 (CH2N), 127.0 (ar CH),
128.1 (ar CH), 128.7 (ar CH), 130.6 (ar CH), 131.0 (ar
CH), 132.9 (ar Cq), 134.6 (ar CH), 135.2 (ar Cq), 137.2
(ar CH), 146.0 (ar Cq). 29Si-NMR (C6D6): l=9.5
(PhSiCl2), −23.6 (Ar2SiCl).
3.1.13. 1-{Bis[2%-(dimethylaminomethyl)phenyl]-
chlorosilyl}-1-chlorodibenzo[b,d]silole (20)
A solution of 2.21 g (2.49 mmol) of 1 and 1.88 g
(7.47 mmol) of 19 in 40 ml of toluene was stirred for 17
h at 55 °C. The solvent was removed in vacuo and the
remaining yellow–orange solid was washed with 20 ml
of dry hexane to give 3.05 g (75%) of 20 as yellow
1
crystals (m.p. 85–86 °C), which are, according to H-
3.1.16. Reaction of 1 with 25
NMR spectrum, contaminated with traces of an
unidentified compound. H-NMR (C6D6): l=1.66 (s,
A solution of 258 mg (0.29 mmol) of 1 and 215 mg
(0.80 mmol) of 25 in 5 ml toluene was stirred for 5 days
at r.t. The suspension was filtered. After removal of the
solvent from the filtrate in vacuo 293 mg (99%) of 17b
were obtained as a colorless solid. The white solid,
which was filtered off, was insoluble in hydrocarbons,
etheral solvent and halogenated solvents. Anal. for the
precipitate found: C, 51.65; H, 6.59; N, 6.09%.
1
12H, NMe2), 2.90, 3.40 (AB system, 4H, CH2N, 2JAB
=
3
4
13 Hz), 7.03 (ddd, Jꢁ3J=7 Hz, J=1 Hz, ar H, 2H),
3
7.12–7.18 (m, 8H, ar H), 7.49 (d, J=8 Hz, 2H, ar H),
3
4
7.90 (dd, J=6 Hz, J=1 Hz, 2H, ar H), 8.38 (dd,
3J=8 Hz, 4J=1 Hz, 2H, ar H). 13C-NMR (C6D6):
l=45.1 (NMe2), 64.3 (CH2N), 121.6 (ar CH), 126.9 (ar

J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
35
3.1.17. 1,2-Dichloro-1-[2-(dimethylaminomethyl)-
phenyl]-2,2-diphenyl-1-(2,4,6-trimethylphenyl)disilane
(26b)
ml of hexane were added to the remaining solid. The
resulting suspension was filtered to yield 2.30 g (82%) of
1
31 as colorless crystals (m.p. 116–119 °C). H-NMR
A solution of 432 mg (0.51 mmol) of 3 and 315 ml
(1.50 mmol) of 9b in 20 ml of toluene was stirred for 3
days at 80 °C. The solvent was removed in vacuo and
20 ml of pentane were added to the residue. The
resulting suspension was filtered leaving behind 642 mg
(80%) of 26b as colorless crystals (m.p. 130–132 °C).
1H-NMR (C6D6): l=1.82 (s, o-Me, 6H), 2.04 (s, p-Me,
3 H), 2.47 (s, NMe2, 6H), 2.43, 3.37 (AB system,
2JAB=13 Hz, 2H, CH2N), 6.64 (s, ar H, 2H), 6.90–7.13
(C6D6): l=1.74 (s, 6H, CH3), 2.00 (s, 3H, CH3), 2.01
(s, 3H, CH3), 2.47 (s, 6H, CH3), 2.50 (s, 6H, CH3), 2.81
2
3.42 (AB system, JAB=13 Hz, 2H, CH2), 6.59 (s, 4H,
3
ar H), 6.99–7.22 (m, 3H, ar H), 8.32 (d, J=7 Hz, 1H,
ar H). 13C-NMR (C6D6): l=20.9 (p-Me), 25.4 (o-Me),
26.0 (o-Me), 45.3 (NMe2), 64.5 (CH2N), 127.5 (ar CH),
128.8 (ar CH), 129.8 (ar CH), 130.5 (ar CH), 130.8 (ar
CH), 133.8 (ar Cq), 137.6 (ar CH), 140.2 (ar Cq), 141.2
(ar Cq), 144.7 (ar Cq), 145.5 (ar CH), 145.7 (ar Cq),
146.3 (ar Cq). 29Si-NMR (C6D6): l=9.4 (SiMesCl2),
−9.0 (SiArMesCl). MS (EI, 70 eV), m/z (%): 533 (16)
[M+, correct isotope pattern], 380/82/84 (100/76/18)
[M++HꢀMesꢀCl], 350/52/54 (28/24/8) [380–2 Me],
316/318 (64/22) [MesArClSi]+, 306/308 (12/8)
[MesArCl2Si+ꢀHꢀNMe2], 217/19 (44/20) [MesCl2Si]+,
120 (100) [MesH]+, 105 (68) [MesH+ꢀMe].
3
(m, ar H, 10H), 7.69 (dd, J=6 Hz, 2H, ar H), 8.14
3
(dd, J=8 Hz, 4J=3 Hz, 2H, ar H). 13C-NMR (C6D6):
l=21.0 (Me), 25.3 (Me), 45.8 (CH3N), 64.9 (CH2N),
127.2 (ar CH), 128.2 (ar CH), 129.6 (ar CH), 130.0 (ar
CH), 130.2 (ar CH), 130.5 (ar CH), 134.0 (ar Cq), 134.5
(ar Cq), 134.9 (ar Cq), 136.5 (ar CH), 136.7 (ar CH),
138.5 (ar CH), 139.4 (ar Cq), 144.6 (ar Cq), 145.5 (ar
Cq), 146.0 (ar Cq). 29Si-NMR (C6D6): l= −2.1
(SiPh2Cl), −15.0 (SiArMesCl).
3.1.20. Reaction of 1 with 32b
A solution of 100 mg (296 mmol) of 32b and 88 mg
(99 mmol) of 1 in 0.4 ml of C6D6 was heated for 60 h at
90 °C. The 1H-NMR and 29Si-NMR spectra of the
product mixture showed that, besides a small amount
of 32b, dichlorosilane 17b and dichlorodisilane 18b
were formed as major products in a 4:1 ratio.
3.1.18. 1-Chloro-1-{[2%-(dimethylaminomethyl)-
phenyl][(2,4,6-trimethylphenyl]chlorosilyl}-
2,3,4,5-tetraphenyl-1-silacyclopentadiene (29)
A solution of 799 mg (1.75 mmol) of 21 and 511 mg
(0.61 mmol) of 3 in 20 ml of toluene was heated for 24
h at 90 °C. The solvent was removed in vacuo and the
residue was suspended in 20 ml of pentane. After
filtration of the suspension 453 mg (35%) of 29 re-
mained as a white solid (m.p. 73–75 °C). 1H-NMR
(C6D6): l=1.76 (s, 6H, o-Me), 2.00 (s, 3H, p-Me), 2.31
(s, 6H, NMe2), 2.65 3.10 (AB system, 2JAB=13 Hz, 2H,
CH2N), 6.53 (s, ar H, 2H), 6.66–7.23 (br.m, 19H, ar
3.1.21. Reaction of 1 with 32a
A solution of 72 mg (0.27 mmol) of 32a and 80 mg
(0.09 mmol) of 1 in 0.4 ml of C6D6 was heated for 84 h
at 90 °C. In the product mixture small amounts of 33a
1
were identified by comparing the H-NMR spectrum
with that of an authentic sample besides the starting
materials and unknown compounds.
3
4
H), 7.40 (dd, J=8 Hz, J=1 Hz, 2H, ar H), 7.49 (d,
3
4
3J=7 Hz, 2H, ar H), 8.31 (dd, J=8 Hz, J=1 Hz,
1H, ar H). 13C-NMR (C6D6): l=21.4 (Me), 25.2 (Me),
45.6 (NMe2), 64.7 (CH2N), 125.6 (ar CH), 126.2 (ar
CH), 126.3 (ar CH), 126.7 (ar CH), 126.8 (ar CH),
127.6 (ar CH), 127.8 (ar CH), 128.1 (ar CH), 128.5 (ar
CH), 128.8 (ar CH), 128.9 (ar CH), 129.3 (ar CH),
129.5 (ar CH), 129.7 (ar CH), 129.8 (ar CH), 129.9 (ar
CH), 129.9 (ar CH), 130.0 (ar CH), 130.1 (ar CH),
134.3 (ar CH), 135.9 (ar Cq), 137.1 (ar Cq), 138.2 (ar
CH), 138.5 (ar Cq), 138.6 (ar Cq), 138.8 (ar Cq), 139.5
(ar Cq), 139.6 (ar Cq), 141.1 (ar Cq), 144.0 (ar Cq), 145.4
(ar Cq), 155.3 (ar Cq), 156.9 (ar Cq), 157.3 (ar Cq).
29Si-NMR (C6D6): l=0.6, −21.3. MS (FAB, 3-NBA),
m/z (%): 736/38/40 (70/54/14) [M++H], 700/02/04 (50/
24/B1) [(M+ꢀCl], 316/318 (30/10) [ArMesClSi]+.
3.1.22. Reaction of 1 with 27b
A solution of 47 mg (0.14 mmol) of 27b and 40 mg
(45 mmol) of 1 in 0.5 ml of C6D6 was heated for 2 h at
1
45 °C. H-NMR spectroscopic analysis showed 18b to
be the major product besides minor amounts of 17b
and 27b.
3.1.23. Reaction of 3 with 17b
A solution of 52 mg (0.14 mmol) of 17b and 40 mg
(47 mmol) of 3 in 0.5 ml of C6D6 was heated for 2 h at
1
85 °C. H-NMR spectroscopic analysis showed 18b to
be the major product besides minor amounts of 27b
and 17b.
3.1.24. 2-(Dimethylaminomethyl)phenyl-(2,4,6-
trimethylphenyl)silane (27a)
A solution of 460 mg (1.31 mmol) 27b in 5 ml of a
1:1 mixture of THF–Et2O (1:1) was added to a stirred
suspension of 105 mg (2.76 mmol) of LiAlH4 in 5 ml of
Et2O at 0 °C. The suspension was warmed to r.t., the
3.1.19. 1,2,2-Trichloro-1-[2-(dimethylaminomethyl)-
phenyl]-1,2-bis-(2,4,6-trimethylphenyl)disilane (31)
A solution of 1.49 g (1.80 mmol) of 3 and 1.34 g
(5.30 mmol) of 30 in 35 ml of toluene was stirred for 17
h at 85 °C. The solvent was removed in vacuo and 30

36
J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
solvent was removed in vacuo and 15 ml of Et2O were
added to the residue. After filtration of the resulting
suspension 0.5 ml of H2O was added to the filtrate at
−78 °C. The resulting suspension was warmed to r.t.
and filtered. The solvent was removed in vacuo from
the filtrate leaving behind 279 mg (75%) of 27a as a
NMR (C6D6): l=1.71 (s; 12H, NMe2), 3.17, 3.23 (AB
2
system, JAB=14 Hz, 4H, CH2N), 6.95–7.15 (m, 14H,
3
4
ar H), 7.18 (ddd, Jꢁ3J=8 Hz, J=1 Hz, 2H, ar H),
7.55 (d, 3J=8 Hz, 2H, ar H), 7.60 (dd, 3J=8 Hz,
4J=1 Hz, 4H, ar H), 7.87 (dd, J=8 Hz, J=1 Hz,
3
4
4H, ar H), 8.02 (d, J=7 Hz, 2H, ar H). 13C-NMR
3
1
colorless oil. H-NMR (C6D6): l=1.96 (s, 6H, NMe2),
(C6D6): l=45.0 (NMe2), 63.8 (CH2N), 126.4 (ar CH),
128.1 (ar CH), 128.3 (ar CH), 128.9 (ar CH), 129.8 (ar
CH), 130.3 (ar CH), 130.6 (ar CH), 132.9 (ar Cq), 134.0
(ar Cq), 135.1 (ar Cq), 135.8 (ar CH), 137.6 (ar CH),
138.0 (ar CH), 146.6 (ar Cq). 29Si-NMR (C6D6): l= +
3.3 (SiCl), +1.2 (SiCl), −38.3 (SiPh2). MS (EI, 70 eV),
m/z (%): 730 (1) [M]+, 695 (1) [M+ꢀCl], 598/596 (4/5)
[M+ꢀAr], 333/331 (3/9) [Ar2SiCl]+, 297 (18) [Ar2SiH]+,
259 (100), 217 (52) [Ph2SiCl]+, 182 (23) [Ph2Si]+.
C42H44N2Si3Cl2 (730.2189): correct HRMS.
2.18 (s, 3H, p-Me), 2.45 (s, 6H, o-Me), 3.29 (s, 2H,
2
CH2N), 5.28 (s(d, JSiH=209 Hz), 2H, SiH), 6.83 (s,
2H, ar H), 6.98 (dd, 2·3J=7 Hz, 1H, ar H), 7.08 (d,
3
3J=7 Hz, 1H, ar H), 7.10 (d, J=7 Hz, 1H, ar H),
7.56 (d, 3J=7 Hz, 1H, ar H). 13C-NMR (C6D6):
l=21.3 (Me), 23.7 (Me), 43.9 (NMe2), 64.5 (CH2N),
127.2 (ar CH), 127.9 (ar CH), 128.7 (ar CH), 129.7 (ar
CH), 130.7 (ar Cq), 133.2 (ar Cq), 137.5 (ar CH), 138.7
(ar Cq), 144.7 (ar Cq), 146.5 (ar Cq). 29Si-NMR (C6D6):
1
4
l= −55.6 (dt, JSiH=209 Hz, JSiH=6 Hz). MS (EI,
70 eV), m/z (%): 282 (4) [M+−1], 237 (5)
[M+ꢀHꢀHNMe2], 223 (12) [M+ꢀCH2NMe2ꢀMeꢀH],
164 (100) [M+ꢀMes], 148 (30) [M+ꢀHꢀAr], 135 (8)
[ArH]+, 119 (20) [Mes]+, 91 (12) [C7H7]+, 58 (18)
[CH2NMe2]+. Anal. Calc. for C18H25NSi (283.49): C
76.26; H, 8.89, Found: C 76.56; H, 9.12%.
3.2.2. 1,1,3,3-Tetrakis[2-(dimethylaminomethyl)-
phenyl]-2,2-diphenyltrisilane (37a)
(a) A solution of 201 mg (0.23 mmol) of 1 and 326
mg (0.68 mmol) of 10a in 10 ml of toluene was heated
for 6 days at 90 °C. The cloudy solution was filtered
and the solvent was removed in vacuo from the filtrate
leaving behind 467 mg (89%) of 37a as a colorless oil.
(b) Heating of a solution of 33 ml (0.18 mmol) of 9a and
106 mg (0.12 mmol) of 1 in 0.5 ml of C6D6 for 6 days
at 90 °C gave after removal of the solvent 125 mg
(90%) of 37a. 1H-NMR (C6D6): l=1.89 (s, 24H,
NMe2), 3.31, 3.43 (AB system, 2JAB=14 Hz, 8H,
3.1.25. Reaction of 1 with 27a
A solution of 50 mg (0.18 mmol) of 27a and 52 mg
(59 mmol) of 1 in 0.5 ml of C6D6 was heated for 2 h at
60 °C and additional 15 h at 80 °C. The 1H-NMR
spectrum of the product mixture showed the signals of
17a besides that of starting material 27a; no signals of
1 could be detected.
1
CH2N), 5.85 (s (d, JSiH=197 Hz), 2H, SiH), 6.91 (dd,
3
3J=7 Hz, J=7 Hz, 4H, ar H), 7.03–7.16 (m, 10H, ar
3
3
H), 7.45 (d, J=8 Hz, 4H, ar H), 7.57 (d, J=7 Hz,
3
4
3.1.26. Reaction of 3 with 17a
4H, ar H), 7.63 (dd, J=7 Hz, J=2 Hz, 2H, ar H).
13C-NMR (C6D6): l=45.1 (NMe2), 64.5 (CH2N), 126.1
(ar CH), 128.1 (ar CH), 128.9 (ar CH), 129.3 (ar CH),
134.4 (ar Cq), 135.9 (ar Cq), 136.5 (ar CH), 137.5 (ar
CH), 138.4 (ar CH), 146.1 (ar Cq). 29Si-NMR (C6D6):
A solution of 45 mg (0.15 mmol) of 17a and 42 mg
(50 mmol) of 3 in 0.5 ml of C6D6 was heated for 18 h at
1
90 °C. The H-NMR spectrum of the product mixture
showed the signals of 27a besides that of starting
material 17a; no signals of 1 could be detected.
1
3
l= −40.8 (dt, JSiH=198 Hz, JSiH=6 Hz, SiAr2H),
−41.4 (SiPh2).
3.2. Formation of trisilanes by silylene insertion
3.2.3. 1,3-Dichloro-1,1,3,3-tetrakis[2-(dimethyl-
3.2.1. 1,3-Dichloro-1,1-bis[2-(dimethylaminomethyl)-
phenyl]-2,2,3,3-tetraphenyltrisilane (36)
aminomethyl)phenyl]-2,2-diphenyltrisilane (37b)
(a) A solution of 0.90 g (1.01 mmol) of 1 and 1.67 g
(3.03 mmol) of 10b in 8 ml of toluene was heated for 2
h at 70 °C. The solvent was removed in vacuo, the
resulting residue was suspended in 10 ml of pentane
and the suspension was filtered. The remaining solid
was dissolved in a mixture of ca. 1 ml of THF and 2 ml
of hexane. Storing the solution at +3 °C for 16 h
yielded 2.10 g (78%) of 37b as colorless crystals. (b) A
solution of 21.4 g (24 mmol) of 1 and 7.5 ml (36 mmol)
of 9b in 100 ml of toluene was heated for 2 h at 70 °C.
The solvent was removed in vacuo, 6.18 g of the
resulting residue (total: 30 g) were suspended in 100 ml
of pentane and the suspension was filtered. The remain-
ing solid was dissolved in a mixture of ca. 10 ml of
A solution of 100 mg (0.11 mmol) of 1 and 147 mg
(0.34 mmol) of 35 in 0.5 ml of C6D6 was heated for 16
h at 45 °C. 1H-NMR spectroscopic analysis of the
reaction mixture at this point showed that still some 35
was present, although all 1 was consumed. Addition of
further 15 mg (0.02 mmol) of 1 and heating for addi-
tional 3 h at 60 °C did not lead to further conversion.
The solvent was removed in vacuo and the residue was
suspended in 5 ml of pentane. After filtration of the
suspension, the filtrate was reduced in vacuo to half of
its volume and stored overnight at 3 °C leading to 85
mg (35%) of 36 as colorless crystals (m.p. 106–108 °C),
1
which were still contaminated with traces of 35. H-

J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
37
THF and 20 ml of hexane. The solution was kept at
+3 °C overnight and 4.70 g (76%) of 37b was isolated
as colorless crystals (m.p. 161–162 °C). 1H-NMR
(C6D6): l=1.77 (s; 24H, NMe2), 3.16, 3.24 (AB system,
2JAB=14 Hz, 8H, CH2N), 6.95–7.10 (m, 10H, ar H),
64.4 (CH2N), 126.4 (ar CH), 128.9 (ar CH), 129.5 (ar
CH), 136.1 (ar Cq), 137.4 (ar CH), 146.0 (ar Cq).
29Si-NMR (C6D6): l= −17.6 (SiMe3), −39.6 (d,
1JSiH=186 Hz, SiAr2H). IR (film): w˜ =2125 cm−1
(SiH). MS (EI, 70 eV) m/z (%): 369 (8) [M+ꢀH], 355 (4)
[M+ꢀMe], 326 (10) [M+ꢀNMe2], 297 (100) [M+
ꢀSiMe3], 236 (55) [M+ꢀAr], 134 (7) [Ar]+, 73 (14)
[SiMe3]+, 58 (12) [CH2NMe2]+. Anal. Calc. for
C21H34N2Si (370.68): C 68.23; H, 9.00; N, 7.58; Found:
C 68.16; H, 8.93; N, 7.37%.
3
3
4
7.20 (ddd, J=8 Hz, J=7 Hz, J=1 Hz, 4H, ar H),
3
7.70 (d, J=8 Hz, 4H, ar H), 8.00–8.15 (m, 8H, ar H).
13C-NMR (C6D6): l=44.1 (NMe2), 63.4 (CH2N), 126.1
(ar CH), 128.4 (ar CH), 128.9 (ar CH), 129.7 (ar CH),
130.8 (ar CH), 133.7 (ar Cq), 134.1 (ar Cq), 137.6 (ar
CH), 138.5 (ar CH), 146.8 (ar Cq). 29Si-NMR (C6D6):
l= +5.5 (SiAr2Cl), −36.7 (SiPh2). MS (FAB, NOE,
pos. mode), m/z (%): 846 (3) [M++H], 807 (100); (EI,
70 eV), m/z (%): 550/548 (8/12) [M+ꢀAr2Si], 416/414
(79/100) [M+ꢀAr2SiꢀAr]. Anal. Calc. for C48H58N4-
Si3Cl2 (846.17): C, 68.13; H, 6.91, Found: C 68.05; H,
6.83%.
3.3.3. 1-Chloro-2,2-bis[2-(dimethylaminomethyl)phenyl]-
1,1-bis(2,4,6-trimethylphenyl)disilane (33c)
A suspension of 2.60 g (4.38 mmol) of 18a and 100
mg (14.4 mmol) of finely cut lithium in 42 ml of THF
was vigorously stirred for 19 h at r.t. The liquid phase
was transferred through a Teflon cannula by means of
a positive argon pressure to a solution of 2.57 g (7.60
mmol) of 32b in 20 ml of THF at 0 °C during 10 min.
The reaction mixture was allowed to warm up to r.t.
and was stirred for additional 20 h. The solvent was
removed in vacuo and the residue suspended in 50 ml
of hexane. After filtration of the suspension the remain-
ing residue was washed several times by recondensation
of the solvent. The filtrate was concentrated in vacuo to
a volume of ca. 7 ml. At −20 °C 3.41 g (75%) of 33c
precipitated from the solution as colorless crystals (m.p.
155 °C). 1H-NMR (C6D6): l=1.95 (s; 12H, NMe2),
2.04 (s; 6H, Me), 2.36 (s; 12H, Me), 2.95, 3.36 (AB
3.3. Formation of disilanes by nucleophilic substitution
3.3.1. 1,1,2,2-Tetrakis[2-(dimethylaminomethyl)-
phenyl]disilane (18a)
A suspension of 13.63 g (40.9 mmol) of 17c in 200 ml
of toluene and 1.92 g (49.1 mmol) of finely cut potas-
sium was stirred for 48 h at r.t. The suspension was
filtered and the solvent was removed from the filtrate in
vacuo leaving behind 11.02 g (91%) of 18a as an
analytically pure, crystalline solid (m.p. 91–92 °C).
2
1
system, J=14 Hz, 4H, CH2N), 5.93 (s (d, JSiH=204
3.3.2. 1,1-Bis[2-(dimethylaminomethyl)phenyl]-
2,2,2-trimethyldisilane (6b)
Hz); 1H, SiH), 6.61 (s, 4H, ar H), 7.01 (ddd, Jꢁ3J=7
3
Hz, 4J=1 Hz, 2H, ar H), 7.19 (ddd, 3Jꢁ3J=7 Hz,
(a) A suspension of 2.50 g (7.60 mmol) 18a, 626 mg
(16.00 mmol) finely cut potassium and 1.26 ml (9.97
mmol) of Me3SiCl (5) in 20 ml of toluene was stirred
for 4 days at r.t. The suspension was filtered and the
solvent was removed from the filtrate in vacuo leaving
behind the crude product as an oil. Distillation at
200 °C/10−3 torr gave 1.34 g (49%) of 6b as colorless
oil. (b) 13 mg (1.9 mmol) of finely cut lithium were
added to a solution of 560 mg (0.94 mmol) of 18a in 10
ml of THF and the resulting suspension was stirred for
16 h at r.t. After filtration of the suspension 0.27 ml
(2.1 mmol) of 5 were added to the filtrate at −78 °C
and the solution was allowed to warm up to r.t. The
solvent was removed in vacuo and the residue was
suspended in 15 ml of Et2O. The suspension was filtered
and the solvent was removed in vacuo from the filtrate.
Kugelrohr distillation of the remaining oil yielded to
439 mg (63%) of 6b as a colorless oil (boiling point
4J=1 Hz, 2H, ar H), 7.47 (d, J=7 Hz, 2H, ar H),
3
8.22 (dd, J=7 Hz, J=1 Hz, 2H, ar H). 13C-NMR
(C6D6): l=20.9 (Me), 24.4 (Me), 45.2 (NMe2), 63.9
(CH2N), 126.3 (ar CH), 128.8 (ar CH), 129.7 (ar CH),
130.0 (ar CH), 132.9 (ar Cq), 133.0 (ar Cq), 138.5 (ar
CH), 139.5 (ar Cq), 144.2 (ar Cq), 146.4 (ar Cq). 29Si-
3
4
NMR (C6D6): l= +1.8 (SiMes2Cl), −44.8 (d, 1JSiH
=
204 Hz, SiAr2H). MS (EI, 70 eV), m/z (%): 598 (B1)
[M]+, 562 (1) [Ar2SiꢁSiMes2+], 553 (1) [M+ꢀNMe2ꢀH],
538 (3) [M+ꢀCH2NMe2ꢀ2H], 464 (11) [M+ꢀAr], 331 (6)
[M+ꢀAr2Si], 297 (100) [Ar2SiH]+, 120 (22) [MesH]+, 58
(8) [CH2NMe2]+. C36H47N2Si2Cl (548.1637): correct
HRMS. Anal. Calc. for C36H47N2Si2Cl (599.41): C
72.14; H, 7.90; Found: C 72.88; H, 8.27%.
3.3.4. 1,1,3,3-Tetrakis[2-(dimethylaminomethyl)-
phenyl]-2,2-dimethyltrisilane (38)
1
(b.p.) 180 °C/0.001 torr). H-NMR (C6D6): l=0.30 (s;
A suspension of 317 mg (0.53 mmol) of 18a and 8 mg
(1.2 mmol) of finely cut lithium in 5 ml of THF was
stirred at r.t. for 3.5 h. After 1.5 h of supersonic
irradiation it was stirred for additional 1 h at r.t. The
suspension was filtered and the filtrate was transferred
through a Teflon cannula by means of a positive argon
9H, SiMe3), 1.94 (s; 12H, NMe2), 3.35, 3.42 (AB sys-
tem, 2J=13 Hz, 4H, CH2N), 5.27 (s (d, 1JSiH=186
3
Hz); 1H, SiH), 7.08–7.22 (m, 4H, ar H), 7.34 (d, J=7
3
4
Hz, 2H, ar H), 7.74 (dd, J=7 Hz, J=2 Hz, 2H; ar
H). 13C-NMR (C6D6): l= −0.1 (SiMe3), 45.0 (NMe2),

38
J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
3.4. Transformations of disilanes
pressure to solution of 0.2 ml (1.6 mmol) of 7a in 5 ml
of THF at 0 °C. The resulting suspension was stirred
for 12 h at r.t. and filtered. The solvent was removed
from the filtrate and the residue was suspended in 10 ml
of hexane. After filtration the solvent was removed
from the filtrate in vacuo leaving behind 334 mg (97%)
of crude 38 as a viscous oil. Distillation at 300 °C/10−4
3.4.1. 1,1-Bis[2-(dimethylaminomethyl)phenyl]-
2,2,2-trimethyldisilane (6b)
A suspension of 62 mg (0.15 mmol) of 6a and 10.0
mg (0.53 mmol) of LiAlH4 in 2 ml of Et2O was stirred
for 15 min at r.t. The solvent was removed in vacuo
and the residue was suspended in 5 ml of wet hexane.
The resulting suspension was filtrated and the solvent
was removed from the filtrate in vacuo leaving behind
28 mg (51%) of 6b as a colorless, 1H-NMR spectroscop-
ically pure oil.
1
torr gave 151 mg (43%) of H-NMR spectroscopically
1
pure 38. H-NMR (C6D6): l=0.50 (s, 6H, SiMe2), 1.95
1
(s, 24H, NMe2), 3.39 (s, 8H, CH2N), 5.43 (s (d, JSiH
=
191 Hz); 2H, Ar2SiH), 7.01 (dd, Jꢁ3J=7 Hz, 4H, ar
H), 7.14 (ddd, J=7 Hz, J=7 Hz, J=1 Hz, 4H, ar
3
3
3
4
3
3
H), 7.35 (d, J=7 Hz, 4H, ar H), 7.67 (d, J=7 Hz,
4H, ar H). 13C-NMR (C6D6): l= −2.7 (SiMe2), 44.9
(NMe2), 64.8 (CH2N), 126.3 (ar CH), 128.9 (ar CH),
129.4 (ar CH), 135.9 (ar Cq), 137.8 (ar CH), 145.6 (ar
3.4.2. 1,1-Bis[2-(dimethylaminomethyl)phenyl]-
2,2-dimethyldisilane (8d)
436 mg (1.1 mmol) of a 3:1 mixture of 8b and 8c were
suspended in 10 ml of Et2O. This suspension was added
dropwise at 0 °C to a suspension of 73 mg (1.9 mmol)
of LiAlH4 in 10 ml of Et2O. After stirring for 1 h at r.t.
the solvent was removed in vacuo and the residue was
suspended in 10 ml of hexane. After filtration the
solvent was removed from the filtrate leaving behind
342 mg as a viscous oil. It was stirred with wet Et2O,
the solvent was removed in vacuo and distillation of the
remaining oil at 200 °C/10−3 torr gave 184 mg (47%)
Cq). 29Si-NMR (C6D6): l= −36.1 (d, JsiH=191 Hz,
1
Ar2SiH), −44.2 (Me2Si). IR (film): w˜ =2124 cm−1. MS
(EI, 70 eV), m/z (%): 650 (1) [M+ꢀ2H], 608 (1) [M+
ꢀNMe2], 564 (1) [M+ꢀ2NMe2], 355 (4) [M+ꢀAr2SiH],
297 (100) [Ar2SiH]+, 281 (4) [Ar2SiH+ꢀMeꢀH], 238 (5)
[Ar2SiH+ꢀNMe2ꢀMe], 209 (6) [Ar2SiH+ꢀ2NMe2], 134
(2) [Ar]+, 58 (4) [CH2NMe2]+.
1
of 8d at 200 °C/10−3 torr. H-NMR (C6D6): l=0.28
3
3.3.5. 1-Chloro-1-[2-(dimethylaminomethyl)-
(d, J=4 Hz, 6H, SiMe2), 1.90 (s, 12H, NMe2), 3.29,
2
phenyl]-1,2,2-tris(2,4,6-trimethylphenyl)disilane (39a)
A solution of 1.45 g (3.20 mmol) Mes2SiHLi in 20 ml
of toluene was added dropwise over 10–15 min to a
solution of 1.12 g (3.20 mmol) of 27b in 20 ml of
toluene at 0 °C. The resulting suspension was stirred 2
h at 0 °C and for additional 2 h at r.t. The solvent was
evaporated in vacuo and 40 ml of pentane were added
to the residue. The resulting suspension was filtered and
the filtrate was concentrated in vacuo to 5 ml. After 1
week at r.t. 225 mg (13%) of 39a were obtained as
colorless crystals (m.p. 153–155 °C). 1H-NMR
(CDCl3): l=1.84 (s, 6H, NMe2), 1.92 (s, 6H, Me), 2.23
(s, 3H, Me), 2.25 (s, 3H, Me), 2.26 (s, 3H, Me), 2.30 (s,
3H, Me), 2.34 (s, 3H, Me), 2.79, 3.37 (AB sys-
3.39 (AB system, JAB=13 Hz, 4H, CH2N), 4.35 (dsep,
3
3
3J=4 Hz, J=2 Hz, 1H, SiMe2H), 5.23 (d, J=2 Hz
1
(d, JSiH=193 Hz); 1H, SiAr2H), 7.07–7.24 (m, 6H, ar
H), 7.77 (dd, 3J=7 Hz, 4J=2 Hz, 2H, ar H). 13C-
NMR (C6D6): l= −4.6 (SiMe2), 44.7 (NMe2), 65.1
(CH2N), 126.5 (ar CH), 128.8 (ar CH), 129.2 (ar CH),
136.1 (ar Cq), 137.5 (ar CH), 145.9 (ar Cq). 29Si-NMR
(C6D6): l= −37.1 (dsep, 1JSiH=179, 2JSiH=7 Hz,
1
SiMe2H), −35.0 (d, JSiH=193 Hz, SiAr2H). IR (film):
w˜ =2108 cm−1. MS (EI, 70 eV), m/z (%): 355 (1)
[M+ꢀH], 311 (8) [M+ꢀNMe2ꢀH], 297 (100) [M+
ꢀSiMe2H], 252 (18) [M+ꢀSiMe2HꢀNMe2ꢀH], 222 (19)
[M+ꢀAr], 162 (4) [ArSi]+, 134 (3) [Ar]+, 58 (5)
[CH2NMe2]+. C20H32N2Si2 (356.2104): correct HRMS.
1
tem,2JAB=13 Hz, 2H, CH2N), 5.36 (d, JSiH=188 Hz,
3.4.3. 1,1-Bis[2-(dimethylaminomethyl)phenyl]-
2,2-diphenyldisilane (10a)
1H, SiH), 6.66 (s, 2H, ar H), 6.80 (s, 4H, ar H),
6.92–6.98 (m, 1H, ar H), 7.22–7.30 (m, 3H, ar H).
13C-NMR (CDCl3): l=21.1 (Me), 24.0 (Me), 24.5
(Me), 24.7 (Me), 45.1 (NMe2), 63.8 (CH2N), 126.4 (ar
CH), 128.1 (ar Cq), 128.5 (ar CH), 128.7 (ar CH), 129.3
(ar CH), 129.6 (ar CH), 130.6 (ar Cq), 130.6 (ar Cq),
134.8 (ar Cq), 136.8 (ar CH), 138.7 (ar Cq), 139.8 (ar
Cq), 145.0 (ar Cq), 145.6 (ar Cq). 29Si-NMR (CDCl3):
l=1.5 (SiAr2Cl), −51.4 (SiMes2H). MS (EI, 70 eV),
m/z (%): 583 (3) [M]+, 463 (2) [M+ꢀMesꢀH], 448 (8)
[M+ꢀAr], 418 (4) [M+ꢀArꢀ2MeꢀH], 316 (100)
[MesArClSi]+, 147 (9) [MesSi]+, 133 (4) [C9H11N]+, 91
(2) [C7H7]+, 58 (2) [CH2NMe2]+.
A suspension of 56 mg (1.50 mmol) of LiAlH4 and
187 mg (0.63 mmol) of a 2:1 mixture of 10c and 10d in
3 ml of Et2O was stirred for 20 min at r.t. The solvent
was removed in vacuo and 5 ml of hexane were added
to the residue. After filtration of the resulting suspen-
sion the solvent was removed from the filtrate leaving
behind 167 mg (96%) of 10a.
3.4.4. 1,1-Bis[2-(dimethylaminomethyl)phenyl]-2,2-bis-
(4-methylphenyl)disilane (12b)
65 mg (1.71 mmol) of LiAlH4were added at 0 °C to
a suspension of 534 mg (0.98 mmol) of 12a in 15 ml of

J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
39
Et2O, and the suspension was stirred for 1 h at r.t. 31
ml of H2O were added to the reaction mixture at
−78 °C, the solvent was removed in vacuo and 10 ml
of hexane were added to the remaining solid. The
suspension was filtered and the solvent was removed
from the filtrate leaving behind 452 mg (91%) of 12b as
The solvent was removed in vacuo and the residue was
suspended in 10 ml of wet hexane. The resulting sus-
pension was filtered and the solvent was removed from
the filtrate leaving behind 210 mg (41%) of 24b as a
colorless oil. 1H-NMR (C6D6): l=1.82 (s, 12H,
NMe2), 3.24, 3.32 (AB system, 2JAB=13 Hz, 4H,
CH2N), 4.68 (d, 3J=2 Hz (d, 1JSiH=186 Hz), 2H,
1
a colorless waxy solid. H-NMR (C6D6): l=1.87 (s,
3
1
12H, NMe2), 2.03 (s, 6H, CH3), 3.32, 3.34 (AB system,
SiH2), 5.37 (t, J=2 Hz (d, JSiH=206 Hz), 1H, SiH),
6.99–7.17 (m, 9H, ar H), 7.59–7.64 (m, 2H, ar H), 7.88
3
1
2JAB=7 Hz, 4H, CH2N), 5.51 (d, J=3 Hz (d, JSiH
=
3
1
188 Hz); 1H, SiH), 5.65 (d, J=3 Hz (d, JSiH=198
Hz), 1H, SiH), 6.96 (d, J=7 Hz, 4H, ar H), 7.02–7.25
(m, 6H, ar H), 7.64 (d, J=8 Hz, 4H, ar H), 7.84 (dd,
3
(dd, J=7 Hz, 4J=1 Hz, 2H, ar H). 13C-NMR (C6D6):
3
l=44.6 (NMe2), 65.2 (CH2N), 126.6 (ar CH), 128.0 (ar
CH), 128.9 (ar CH), 128.9 (ar CH), 128.9 (ar CH),
133.4 (ar Cq), 135.6 (ar Cq) 136.5 (ar CH), 137.6 (ar
CH), 146.7 (ar Cq). 29Si-NMR (C6D6): l= −42.1 (dtt,
1JSiH=205 Hz, 2JSiH=6 Hz, 3JSiH=5 Hz, Ar2SiH),
3
3J=7 Hz, 4J=1 Hz, 2H, ar H). 13C-NMR (C6D6):
l=21.4 (CH3), 44.8 (NMe2), 65.1 (CH2N), 126.4 (ar
CH), 128.9 (ar CH), 129.0 (ar CH), 129.1 (ar CH),
131.8 (ar Cq), 135.3 (ar Cq), 136.6 (ar CH), 138.2 (ar
CH), 138.5 (ar Cq), 146.0 (ar Cq). 29Si-NMR (C6D6):
l= −31.5 (d, 1JSiH=190 Hz, SiPh2H), −42.2 (d,
1JSiH=194 Hz, SiAr2H). MS (EI, 70 eV), m/z (%): 507
(1) [M+ꢀH], 463 (8) [M+ꢀNMe2ꢀH], 448 (8) [M+
ꢀNMe2ꢀMeꢀH], 374 (10) [M+ꢀAr], 297 (100) [M+
1
2
3
−56.3 (dtt, JSiH=186 Hz, JSiH=6 Hz, JSiH=5 Hz,
PhSiH2). IR (film): w˜ =2134 cm−1. MS (EI, 70 eV), m/z
(%): 403 (1) [M+ꢀH], 359 (3) [M+ꢀNMe2ꢀH], 344 (4)
[M+ꢀNMe2ꢀMeꢀH], 297 (34) [M+ꢀPhSiH2], 281 (8)
[M+ꢀPhSiH2ꢀMeꢀH], 270 (6) [M+ꢀAr], 253 (57) [M+
[M+ꢀ(MeC6H4)2SiHꢀ
ꢀPhSiH2ꢀNMe2],
238
(100)
[M+ꢀPhSiH2ꢀCH2-
ꢀ(MeC6H4)2SiH],
253
(4)
NMe2ꢀH], 208 (23) [M+ꢀPhSiH2ꢀ2NMe2ꢀH], 164 (62)
[M+ꢀPhSiH2ꢀAr+H], 148 (7) [M+ꢀPhSiH2ꢀArꢀMe],
134 (4) [Ar]+, 119 (16) [Ar+ꢀMe], 105 (8) [Ar+ꢀ2Me+
H], 91 (6) [C7H7]+, 58 (16) [CH2NMe2]+, 44 (4)
[NMe2]+. C24H32N2Si2 (404.2104): correct HRMS.
NMe2ꢀH], 238 (8) [M+ꢀ(MeC6H4)2SiHꢀNMe2ꢀMe].
3.4.5. 2,2-Bis(4-chlorophenyl)-1,1-bis[2-(dimethyl-
aminomethyl)phenyl]disilane (14b)
80 mg (2.12 mmol) of LiAlH4 were added at 0 °C to
a suspension of 653 mg (1.06 mmol) of 14a in 15 ml of
Et2O, and the suspension was stirred for 1 h at r.t. 38
ml of H2O were added to the reaction mixture at
−78 °C, the solvent was removed in vacuo and the
residue was suspended with 10 ml of hexane. The
suspension was filtered and the solvent was removed
from the filtrate leaving behind 380 mg (65%) of 14b as
3.4.7. 1,1-Bis(2,4,6-trimethylphenyl)-2,2-bis(2-
(dimethylaminomethyl)phenyl]disilane (33a)
A suspension of 500 mg (0.83 mmol) of 33c and 134
mg (3.53 mmol) of LiAlH4 in 10 ml of Et2O was stirred
for 2 h at r.t. and refluxed for additional 13 h. After
addition of 240 ml (13 mmol) of H2O at −78 °C the
mixture was allowed to warm to r.t. and was stirred for
30 min. The solvent was removed in vacuo and the
residue was extracted once with 30 ml and twice with 5
ml of hexane. The solvent was removed in vacuo from
the collected filtrates leaving behind 310 mg (65%) of
33a as an NMR spectroscopically pure, white solid
1
a colorless waxy solid. H-NMR (C6D6): l=1.78 (s,
3
12H, NMe2), 3.25 (s, 4H, CH2N), 5.22 (d, J=3 Hz (d,
1JSiH=190 Hz), 1H, SiH), 5.47 (d, 3J=3 Hz (d,
1JSiH=201 Hz), 1H, SiH), 6.98 (ddd, 3Jꢁ3J=7 Hz,
4J=2 Hz, 2H, ar H), 7.06–7.12 (m, 8H, ar H), 7.32 (d,
3
4
3J=8 Hz, 4H, ar H), 7.65 (dd, J=7 Hz, J=4 Hz,
2H, ar H). 13C-NMR (C6D6): l=44.6 (NMe2), 65.0
(CH2N), 126.5 (ar CH), 128.5 (ar CH), 129.3 (ar CH),
133.7 (ar Cq), 134.6 (ar Cq), 135.8 (ar Cq), 137.7 (ar
CH), 137.7 (ar CH), 137.9 (ar CH), 145.9 (ar Cq).
1
(m.p. 45–48 °C). H-NMR (C6D6): l=1.90 (s, 12H,
NMe2), 2.07 (s, 6H, Me), 2.31 (s, 12H, Me), 3.04, 3.41
2
(AB system, JAB=13 Hz, 4H, CH2N), 5.75, 5.86 (AB
3
system, JAB=8 Hz, 2H, Si2H2), 6.65 (s, 4H, ar H),
1
29Si-NMR (C6D6): l= −43.0 (d, JSiH=203 Hz), −
4
6.93 (ddd, 3Jꢁ3J=7 Hz, J=1 Hz, 2H, ar H), 7.13
1
31.0 (d, JSiH=192 Hz). MS (EI, 70 eV), m/z (%): 547
(ddd, 3Jꢁ3J=7 Hz, 4J=1 Hz, 2H, ar H), 7.37 (d,
(1) [M+ꢀH], 503 (2) [M+ꢀNMe2ꢀH], 488 (6) [M+
3
4
3J=7 Hz, 2H, ar H), 7.77 (dd, J=7 Hz, J=1 Hz,
2H, ar H). 13C-NMR (C6D6): l=21.0 (Me), 24.2 (Me),
45.0 (NMe2), 64.3 (CH2N), 126.5 (ar CH), 128.8 (ar
CH), 129.0 (ar CH), 129.3 (ar CH), 130.7 (ar Cq), 135.4
ꢀNMe2ꢀMeꢀH], 414 (7) [M+ꢀAr], 297 (100) [M+
ꢀ(ClC6H4)2SiH],
NMe2ꢀH].
253
(100)
[M+ꢀ(ClC6H4)2SiHꢀ
(ar Cq), 137.2 (ar CH), 138.6 (ar Cq), 145.1 (ar Cq),
3.4.6. 1,1-Bis[2-(dimethylaminomethyl)phenyl]-2-
phenyldisilane (24b)
To a suspension of 656 mg (1.29 mmol) of 24a in 10
ml of Et2O 70 mg (1.80 mmol) of LiAlH4 were added at
0 °C and the suspension was stirred for 45 min at r.t.
1
146.0 (ar Cq). 29Si-NMR (C6D6): l= −41.8 (d, JSiH
=
1
2
205 Hz, SiAr2H), −55.7 (dd, JSiH=178 Hz, JSiH=9
Hz, SiMes2H). MS (EI, 70 eV), m/z (%): 563 (30)
[M+ꢀH], 297 (37) [Ar2SiH]+, 91 (100) [C7H7]+.

40
J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
3.4.8. 1-[2-(Dimethylaminomethyl)phenyl]-1,2,2-tris-
(2,4,6-trimethylphenyl)disilane (39b)
CCl4. After stirring for 2 h at r.t. the suspension was
filtered and the remaining solid was washed several
times by recondensation of the solvent. The solvent was
removed from the filtrate in vacuo leaving behind the
crude product. It was suspended in 35 ml of hexane and
the resulting suspension was filtered. The solvent was
removed from the filtrate in vacuo leaving behind 819
mg (77%) of 33b as NMR spectroscopically pure, color-
A suspension of 445 mg (0.76 mmol) of 39a and 280
mg (11.73 mmol) of LiAlH4 in 20 ml of Et2O was
refluxed for 19 h. The suspension was filtered and the
solvent was removed from the filtrate in vacuo. Distilla-
tion of the crude product (170 °C/10−4 torr) gave 197
1
mg (47%) of 39b as a colorless oil. H-NMR (C6D6):
1
l=1.85 (s, 6H, NMe2), 2.06 (s, 6H, Me), 2.10 (s, 3H,
less solid (m.p. 63–65 °C). H-NMR (C6D6): l=2.00
Me), 2.32 (s, 6H, Me), 2.35 (s, 6H, Me), 2.43 (s, 6H,
(s, 12H, NMe2), 2.04 (s, 6H, Me), 2.41 (s, 12H, Me),
2
2
Me), 2.98, 3.30 (AB system, JAB=13 Hz, 2H, CH2N),
3.22, 3.65 (AB system, JAB=15 Hz, 4H, CH2N), 6.63
3
3
5.89, 5.94 (AB system, JAB=7 Hz, 2H, SiH), 6.65 (s,
(s, 4H, ar H), 6.92 (dd, Jꢁ3J=7 Hz, 2H, ar H), 7.24
3
4H, ar H), 6.72 (s, 2H, ar H), 6.92 (dd, Jꢁ3J=8 Hz,
(dd, 3J=7 Hz, 3J=8 Hz, 2H, ar H), 7.86 (d, 3J=8 Hz,
3
3
1H, ar H), 7.12 (dd, Jꢁ3J=8 Hz, 1H, ar H), 7.28 (d,
2H, ar H), 8.06 (d, J=7 Hz, 2H, ar H). 13C-NMR
3
3J=8 Hz, 1H, ar H), 7.98 (d, J=8 Hz, 1H, ar H).
(C6D6): l=20.9 (Me), 25.0 (Me), 45.3 (NMe2), 63.2
(CH2N), 126.0 (ar CH), 129.3 (ar CH), 130.2 (ar CH),
131.0 (ar CH), 132.5 (ar Cq), 137.9 (ar CH), 140.0 (ar
Cq), 144.5 (ar Cq), 147.6 (ar Cq). 29Si-NMR (C6D6):
l= −0.2 (SiMes2Cl), −4.8 (SiAr2Cl). MS (FAB,
NOE), m/z (%): 631 (100) [M+ꢀH].
13C-NMR (C6D6): l=21.1 (Me), 24.1 (Me), 24.3 (Me),
24.8 (Me), 30.2 (o-Me), 44.6 (NMe2), 64.3 (CH2N),
127.0 (ar CH), 128.7 (ar CH), 128.8 (ar CH), 128.9 (ar
CH), 129.1 (ar CH), 129.2 (ar CH), 129.7 (ar CH),
130.5 (ar CH), 130.6 (ar CH), 130.9 (ar CH), 135.8 (ar
Cq), 138.3 (ar CH), 138.5 (ar CH), 138.5 (ar CH), 138.9
(ar CH), 144.6 (2·ar Cq), 145.1 (2·ar Cq), 145.3 (ar Cq),
145.5 (2·ar Cq), 146.8 (ar Cq). 29Si-NMR (C6D6): l= −
44.9 (d, 1JSiH=199 Hz, SiArMesH), −55.9 (dd,
1JSiH=179 Hz, 4JSiH=7 Hz, SiMes2H). MS (EI, 70
eV), m/z (%): 548 (8) [M+ꢀH], 430 (12) [M+ꢀMes], 414
(20) [M+ꢀAr], 400 (4) [M+ꢀMesꢀ2Me], 282 (100)
[ArMesSiH]+, 267 (4) [Mes2SiH]+.
3.5. Thermal stability of di- and trisilanes
3.5.1. Silylene extrusion from 36
A solution of 20 mg (27 mmol) of 36 and 13 ml (118
mmol) of 40 was heated in an NMR tube at 110 °C.
After 13 h the 1H-NMR spectrum of the mixture
showed signals of a 1:1 mixture of 35 and 41 [11]
besides that of left over 40.
3.4.9. 1,2-Dichloro-1,1,2,2-tetrakis[2-(dimethyl-
aminomethyl)phenyl]disilane (18b)
A suspension of 2.50 g (4.20 mmol) of 18a and 1.18
g (8.83 mmol) of N-chlorosuccinimide in 50 ml of CCl4
was stirred for 5 h at 20 °C. The solvent was removed
in vacuo, 50 ml of hexane were added to the residue
and the resulting suspension was filtered. The filtrate
was reduced in vacuo to half of its volume and on
cooling for several days at −15 °C 2.01 g (72%) of 18b
were obtained as a colorless solid.
3.5.2. Silylene extrusion from 37b
(a) A solution of 20 mg (24 mmol) of 37b and 13 ml
(118 mmol) of 40 in 0.4 ml of C6D6 was heated in an
1
NMR tube at 70 °C. After 18 h, the H-NMR spec-
trum showed signals of a 1:1 mixture of 10b and 41
besides that of left over 40. (b) A solution of 47 mg (56
mmol) of 37b and 12 ml (56 mmol) of 9b in 0.4 ml of
C6D6 was heated in an NMR tube at 70 °C for 18 h.
1
The H-NMR spectrum showed only the signals of 10b
3.4.10. 1-Chloro-1,1,2,2-tetrakis[2-(dimethyl-
aminomethyl)phenyl]disilane (18c)
besides traces of left over 9b.
A suspension of 2.27 g (3.81 mmol) of 18a and 1.07
g (8.00 mmol) of N-chlorosuccinimide in 40 ml of
hexane was stirred for 6 h at 20 °C. The suspension
was filtered and the filtrate was reduced to half of its
volume in vacuo. On cooling to −6 °C 1.43 g (59%) of
18c were obtained as colorless crystals (m.p. 80–
82 °C). The mother liquor contained further 18c as
main component besides traces of 18b.
3.5.3. Attempted silylene extrusion from 35
A solution of 20 mg (46 mmol) of 35 and 26 ml (229
mmol) of 40 in 0.4 ml of C6D6 was heated in an NMR
1
tube at 110 °C for 10 h. According to the H-NMR
spectrum, the composition of the reaction mixture was
unchanged.
3.5.4. Attempted silylene extrusion from 42
3.4.11. 1,2-Dichloro-2,2-bis[2-(dimethylaminomethyl)-
phenyl]-1,1-bis(2,4,6-trimethylphenyl)disilane (33b)
A solution of 1.00 g (1.67 mmol) of 33c in 10 ml of
CCl4 was added dropwise to a stirred suspension of 245
mg (1.84 mmol) of N-chlorosuccinimide in 10 ml of
A solution of 20 mg (33 mmol) 7 and 19 ml (166 mmol)
of 42 in 0.4 ml of C6D6 was heated in an NMR tube at
1
90 °C for 15 h. According to the H-NMR spectro-
scopic analysis the composition of the reaction mixture
was unchanged.

J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
41
3.5.5. Silylene extrusion from 10b
may be obtained from the Director of the Cambridge
Crystallographic Data Centre, 12 Union Road, GB-
Cambridge CB2 1EZ.
A solution of 20 mg (36 mmol) of 10b and 20 ml (182
mmol) of 40 in 0.4 ml of C6D6 was heated in an NMR
tube at 110 °C. After 12 h 1H-NMR spectroscopic
analysis showed the signals of 9b and 41 besides those
of starting material; the grade of conversion was 20%.
Further heating did not result in increased amounts of
9b and 41, but favors the formation of decomposition
products of unknown structure.
Acknowledgements
This work was supported by the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen
Industrie.
3.5.6. Silylene extrusion from 18b
A solution of 60 mg (90 mmol) of 18b and 0.10 ml (0.91
References
mmol) of 40 in 0.4 ml of C6D6 was heated for 19 h at
1
70 °C. The H-NMR spectrum showed the signals of
[1] See e.g.: (a) M. Weidenbruch, K. Kramer, A. Scha¨fer, J.K.
Blum, Chem. Ber. 118 (1985) 107;
starting materials and traces of an unidentified decom-
position product. To this solution 5 mg (6 mmol) of 1
were added and the mixture was heated at 65 °C for 19
(b) J. Belzner, N. Detomi, H. Ihmels, M. Noltemeyer, Angew.
Chem. 106 (1994) 1949; Angew. Chem. Int. Ed. Engl. 33 (1994)
1854;
(c) M. So¨ldner, M. Sandor, A. Schier, H. Schmidbaur, Chem.
Ber. Recl. 533 (1997) 61;
1
h. H-NMR spectroscopic analysis showed besides sig-
nals of excess 40 only the signals of a 1:1 mixture of 17b
and 41.
(d) K. Tamao, M. Asahara, T. Saeki, A. Toshimitsu, Chem.
Lett. (1999) 335.
[2] R. West, in: E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.),
Comprehensive Organometallic Chemistry II: A Review of the
Literature 1982–1994, vol. 2, Pergamon Press, Oxford, 1995, p.
77.
[3] See e.g.: (a) W.-C. Joo, J.-H. Hong, S.-B. Choi, H.-E. Son, C.H.
Kim, J. Organomet. Chem. 391 (1990) 27;
3.5.7. Silylene extrusion from 28b
A solution of 30 mg (0.05 mmol) of 28b and 27 ml (0.24
mmol) of 40 in 0.4 ml of C6D6 in an NMR tube was
heated at 90 °C. 1H-NMR spectroscopy showed the
mixture to be unchanged after 24 h. About 1 mg of 3 was
added to this mixture and heating at 90 °C was resumed
for additional 15 h. The 1H-NMR spectrum showed
besides signals of excess 40 only the signals of a equimo-
lar mixture of 27b and 1-[2%-(dimethylaminomethyl)-
phenyl]-1-mesityl-3,4-dimethylsilacyclopent-3-ene.
(b) J.H. Hong, P. Boudjouk, S. Castellino, Organometallics 13
(1994) 3387;
(c) R. West, H. Sohn, U. Bankwitz, J. Calabrese, Y. Apeloig, T.
Mu¨ller, J. Am. Chem. Soc. 117 (1995) 11608;
(d) W.P. Freeman, T.D. Tilley, G.P.A. Yap, A.L. Rheingold,
Angew. Chem. 108 (1996) 960; Angew. Chem. Int. Ed. Engl. 35
(1996) 882.
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(b) H. Sohn, R.R. Huddleston, D.R. Powell, R. West, K. Oka,
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Am. Chem. Soc. 107 (1985) 5552;
(b) M. Weidenbruch, A. Pellmann, Y. Pan, S. Pohl, W. Saak, H.
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[6] (a) T. Kawase, S.A. Batcheller, S. Masamune, Chem. Lett.
(1987) 227;
3.5.8. Single crystal X-ray diffraction analysis of 39a
Monoclinic, space group P21/n, a=8.572(2), b=
37.4218(17), c=10.322(2) pm, i=96.10(3)°; V=
3
3292.9(11) A , zcalc=1.179 g cm−3, 2[ range from 4 to
,
51°, (−10=h=10, 0=k=45, 0=l=12), Mo–Ka,
u=71.073 pm, T=133 K, crystal dimensions 0.5×
0.4×0.4 mm, 33 615 reflections, 6039 independent
(Rint=0.0361) reflections were used for the structure
refinement; final R values: R1=0.0412 [I\2|(I)],
wR2=0.1014 (all data), residual electron density: 0.298
(b) K. Tamao, G.R. Sun, A. Kawachi, S. Yamaguchi,
Organometallics 16 (1997) 780;
(c) J. Heinicke, S. Mantey, Heteroatom Chem. 9 (1998) 311.
[7] Experiments and calculations show that this reaction possesses
no activation energy: (a) R. Becerra, H.M. Frey, B.P. Mason, R.
Walsh, M.S. Gordon, J. Chem. Soc. Faraday Trans. 91 (1995)
2723;
(b) S. Sakai, M. Nakamura, J. Phys. Chem. 97 (1993) 4960.
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Chemistry of Organic Silicon Compounds, vol. 2, Wiley,
Chichester, 1998, p. 2463.
and −0.253 e A−3. The structure was solved by direct
,
methods using SHELXS [32] and refined against F2 using
a full matrix least squares target (SHELXL-97) [33]. The
2
2
R-values were defined as R1=[ꢀꢁꢁFoꢁ−Fcꢁꢁ /ꢀꢁFoꢁ and
wR2=ꢀw(Fo2 −Fc2)2/ꢀwF4o]1/2. The Si-bound hydrogen
atom was localized in the difference Fourier map and
refined with the help of 1,3-distance restraints. The other
hydrogen atoms were set at geometrically calculated
positions and refined using a riding model.
[9] See e.g.: (a) Y.-S. Chen, P.P. Gaspar, Organometallics 1 (1982)
1410;
(b) U. Herzog, R. Richter, E. Brendler, G. Roewer, J.
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(c) J. Belzner, U. Dehnert, H. Ihmels, M. Hu¨bner, P. Mu¨ller, I.
Uso´n, Chem. Eur. J. 5 (1998) 852.
4. Supplementary material
[10] For oligosilanes with highly coordinated silicon centers see: (a) I.
El-Sayed, Y. Hatanaka, C. Muguruma, S. Shimada, M. Tanaka,
Further details of the crystal structure determinations

42
J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42
N. Koga, M. Mikami, J. Am. Chem. Soc. 121 (1999) 5095 and
references cited therein;
vicinally coordinated by two ammonia molecules, to give two
silylene–ammonia complexes is only 17.8 kcal mol−1
.
(b) K. Tamao, M. Asahara, G.R. Sun, A. Kawachi, J.
Organomet. Chem. 574 (1999) 193;
(c) K. Tamao, M. Asahara, T. Saeki, A. Toshimitsu, Angew.
Chem. 111 (1999) 3520; Angew. Chem. Int. Ed. 38 (1999) 3316.
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of Organosilicon Compounds, vol. 29, Wiley, Chichester, 1989,
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The Chemistry of Organic Silicon Compounds, vol. 2, Wiley,
Chichester, 1998, p. 1339.
[25] The orientation of the lone pair vector was determined by
summation of three normalized vectors, which are collinear with
the three N(1)ꢀC bonds.
[26] It was impossible to prove the purity of some compounds either
by elemental analysis or high resolution mass spectroscopy due
to their extreme sensitivity towards atmospheric moisture.
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Organometallics 3 (1984) 793.
[11] J. Belzner, H. Ihmels, B.O. Kneisel, R.O. Gould, R. Herbst-
Irmer, Organometallics 14 (1995) 305.
[12] This compound was prepared earlier by hydrolysis of 1: J.
Belzner, J. Organomet. Chem. 430 (1992) C51.
[13] (a) K. Tamao, A. Kawachi, Adv. Organomet. Chem. 38 (1995)
1;
(b) J. Belzner, U. Dehnert, in: Z. Rappoport, Y. Apeloig (Eds.),
The Chemistry of Organic Silicon Compounds, vol. 2, Wiley,
Chichester, 1998, p. 779.
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Shiro, J. Am. Chem. Soc. 117 (1995) 11592;
(b) K. Tamao, Y. Tarao, Y. Nakagawa, K. Nagata, Y. Ito,
Organometallics12 (1993) 1113;
For calculations addressing the extrusion of coordinated silyle-
nes from disilanes, see: (c) H. Hildebrandt, B. Engels, Z. Anorg.
Allg. Chem. 626 (2000) 400.
[15] The synthesis of this silacyclopentene from 3 and 40 was de-
scribed earlier (ref. 9c).
[16] In the meantime we succeeded in preparing a stable disilene
using this method: J. Belzner, B. Rohde, to be published.
[17] P. Jutzi, in: A.R. Bassindale, P.P. Gaspar (Eds.), Frontiers of
Organosilicon Chemistry, Royal Society of Chemistry, Cam-
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1997.
[18] J. Belzner, D. Scha¨r, unpublished results.
[19] Unpublished results of ab initio-calculations at the B3LYP/6-
311+G*//B3LYP/6-311+G* level show that for the dissocia-
tion of the parent disilene into two silylenes 55.4 kcal mol−1 are
necessary, whereas the dissociation energy of a disilene, which is