Synthesis of di- and trisilanes with potentially chelating substituents

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

^aInstitut fu¨r Organische Chemie der Georg-August-Uni6ersita¨t Go¨ttingen, Tammannstr. 2, D-37077 Go¨ttingen, Germany

^bInstitut 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

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).

¹Present address: Henkelstr. 282, D-40599 Du¨sseldorf, Germany.

PII: S0022-328X(01)01451-6

26

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

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

Ph₂SiH₂(9a)

Ph₂SiCl₂(9b)

Ph₂SiHCl (9c)

78

83

7

8

9

1

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)

^a8b:8c=3:1.

^b10c: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

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

Li

Ar₂SiHCl (17c)

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

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

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)

^aTwo equivalents NCS, solvent: CCl₄.

^bOne 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 LiAlH₄in 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

^aThe 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 SiN 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 C₆D₆used were

dried by reﬂuxing over sodium benzophenone ketyl and

distilled immediately before use; CDCl₃, CCl₄was 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). C_q, CH, CH₂and 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 l_TMS=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 C₆D₆was 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, ²J_AB=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 C_q), 136.6 (ar CH), 146.0 (ar C_q). 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 C₆D₆was 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, ²J_AB=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 C_q), 136.9 (ar CH), 145.9 (ar C_q).

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 C₆D₆was 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, ¹J_SiH=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 C_q), 137.5 (ar CH), 145.7 (ar C_q). 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, J_AB

=

14 Hz, 4H, CH₂N), 7.04–7.20 (m, 10H, ar H), 7.29 (d,

1

(C₆D₆): l=22.8 (SiMe₂Cl), −41.1 (d, J_SiH=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 C_q), 134.8 (ar C_q), 135.8 (ar CH), 137.5 (ar

CH), 146.0 (ar C_q). 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, J_AB=14 Hz, 4H,

3

1

CH₂N), 4.26 (sep, J=4 Hz (d, J_SiH=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 C_q), 136.8 (ar CH), 145.5 (ar C_q).

²⁹Si-NMR (C₆D₆): l= −16.8 (SiAr₂Cl) l= −35.0

(dsep, ¹J_SiH=182, ²J_SiH=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 C₆D₆was 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, ¹J_SiH=189 Hz), 1H,

3

1

SiH), 5.61 (d, J=3 Hz (d, J_SiH=200 Hz), 1H, SiH),

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, J_AB=13

3

1

ar H), 7.77 (d, J=7 Hz, 2H, ar H). ¹³C-NMR (C₆D₆):

Hz, 4H, CH₂N), 5.72 (s (d, J_SiH=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 C_q), 135.5 (ar C_q), 136.5 (ar CH), 138.1 (ar

CH), 146.0 (at C_q). ²⁹Si-NMR (C₆D₆): l= −30.8

(ddqin, ¹J_SiH=189 Hz, ²J_SiH=5 Hz, ³J_SiH=4 Hz,

SiPh₂H), −42.3 (ddt, ¹J_SiH=200 Hz, ²J_SiH=5 Hz,

³J_SiH=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 C_q), 135.2 (ar CH), 136.7 (ar C_q), 138.2 (ar

CH), 146.1 (ar C_q). ²⁹Si-NMR (C₆D₆): l=3.5

(Ph₂SiCl), −31.9 (dt, ¹J_SiH=209 Hz, ³J_SiH=6 Hz,

Ar₂SiH). 10d: ¹H-NMR (C₆D₆): l=1.80 (s, 12H,

NMe₂), 3.13, 3.34 (AB system, ²J_AB=13 Hz, 4H,

CH₂N), 5.46 (s (d, ¹J_SiH=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 C_q), 134.8 (ar CH), 135.3

J. Belzner et al. / Journal of Organometallic Chemistry 649 (2002) 25–42

33

(ar C_q), 136.9 (ar CH), 137.5 (ar CH), 145.9 (ar C_q).

ꢀ(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

¹J_SiH=189 Hz, J_SiH=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, J_AB=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, J_AB=14 Hz, 4H, CH₂N), 6.92

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 C_q), 134.4 (ar

C_q), 136.0 (ar CH), 137.7 (ar CH), 140.2 (ar C_q), 146.2

(ar C_q). 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 C_q), 133.1 (ar C_q), 137.0

(ar CH), 137.6 (ar CH), 146.6 (ar C_q), 151.0 (ar C_q).

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 C₆D₆and 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, J_AB=14 Hz, 8H, CH₂N), 5.51 (s (dd, J_SiH=200

3

Hz, J_HH=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 C_q), 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 C_q), 138.2 (ar CH), 145.7 (ar C_q). 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, J_AB=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 C_q),

134.0 (ar C_q), 135.6 (ar CH), 137.0 (ar C_q), 137.3 (ar

CH), 137.4 (ar CH), 145.9 (ar C_q). 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 C₆D₆was 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 C_q), 134.3 (ar CH), 136.4 (ar

C_q), 137.4 (ar CH), 145.9 (ar C_q), 148.0 (ar C_q). ²⁹Si-

NMR (C₆D₆): l= −1.0, −19.0.

2

3

(AB system, J_AB=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

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 C_q), 137.5 (ar CH), 146.8

(ar C_q). 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, ²J_AB=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 C_q), 138.0

(ar CH), 138.5 (ar C_q), 138.8 (ar C_q) 140.6 (ar C_q),

145.7 (ar C_q), 156.7 (ar C_q). 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 C₆D₆was 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,²J_AB=13

2

Hz, 4H, CH₂N), 3.39, 3.60 (AB system, J_AB=14 Hz,

1

4H, CH₂N), 5.90 (s, (d, J_SiH=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

ar H), 7.40 (d, J=7 Hz. 2H, ar H), 7.44 (d, J=7 Hz,

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 C_q), 137.0 (ar

C_q), 137.7 (ar CH), 138.8 (ar CH), 145.7 (ar C_q), 146.3

(ar C_q). 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, J_AB

=

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 C_q), 134.6 (ar CH), 135.2 (ar C_q), 137.2

(ar CH), 146.0 (ar C_q). 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, ²J_AB

=

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,

²J_AB=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, J_AB=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 C_q), 137.6 (ar CH), 140.2 (ar C_q), 141.2

(ar C_q), 144.7 (ar C_q), 145.5 (ar CH), 145.7 (ar C_q),

146.3 (ar C_q). 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 C_q), 134.5

(ar C_q), 134.9 (ar C_q), 136.5 (ar CH), 136.7 (ar CH),

138.5 (ar CH), 139.4 (ar C_q), 144.6 (ar C_q), 145.5 (ar

C_q), 146.0 (ar C_q). 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 C₆D₆was 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, ²J_AB=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 C₆D₆was 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 C_q), 137.1 (ar C_q), 138.2 (ar

CH), 138.5 (ar C_q), 138.6 (ar C_q), 138.8 (ar C_q), 139.5

(ar C_q), 139.6 (ar C_q), 141.1 (ar C_q), 144.0 (ar C_q), 145.4

(ar C_q), 155.3 (ar C_q), 156.9 (ar C_q), 157.3 (ar C_q).

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 C₆D₆was 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 C₆D₆was 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 LiAlH₄in 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, J_AB=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 C_q), 134.0

(ar C_q), 135.1 (ar C_q), 135.8 (ar CH), 137.6 (ar CH),

138.0 (ar CH), 146.6 (ar C_q). 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, J_SiH=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 C_q), 133.2 (ar C_q), 137.5 (ar CH), 138.7

(ar C_q), 144.7 (ar C_q), 146.5 (ar C_q). ²⁹Si-NMR (C₆D₆):

1

4

l= −55.6 (dt, J_SiH=209 Hz, J_SiH=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 C₆D₆for 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, ²J_AB=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 C₆D₆was 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, J_SiH=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

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 C_q), 135.9 (ar C_q), 136.5 (ar CH), 137.5 (ar

CH), 138.4 (ar CH), 146.1 (ar C_q). 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 C₆D₆was 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, J_SiH=198 Hz, J_SiH=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 C₆D₆was 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,

²J_AB=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 C_q), 137.4 (ar CH), 146.0 (ar C_q).

²⁹Si-NMR (C₆D₆): l= −17.6 (SiMe₃), −39.6 (d,

¹J_SiH=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

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 C_q), 134.1 (ar C_q), 137.6 (ar

CH), 138.5 (ar CH), 146.8 (ar C_q). 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, J_SiH=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/10⁻³torr 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 C_q), 133.0 (ar C_q), 138.5 (ar

CH), 139.5 (ar C_q), 144.2 (ar C_q), 146.4 (ar C_q). ²⁹Si-

3

4

NMR (C₆D₆): l= +1.8 (SiMes₂Cl), −44.8 (d, ¹J_SiH

=

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, ¹J_SiH=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 LiAlH₄in 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, J_SiH

=

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

4

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 C_q), 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 LiAlH₄in 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/10⁻³torr gave 184 mg (47%)

C_q). ²⁹Si-NMR (C₆D₆): l= −36.1 (d, J_siH=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/10⁻³torr. 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, J_AB=13 Hz, 4H, CH₂N), 4.35 (dsep,

3

³J=4 Hz, J=2 Hz, 1H, SiMe₂H), 5.23 (d, J=2 Hz

1

(d, J_SiH=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 C_q), 137.5 (ar CH), 145.9 (ar C_q). ²⁹Si-NMR

(C₆D₆): l= −37.1 (dsep, ¹J_SiH=179, ²J_SiH=7 Hz,

1

SiMe₂H), −35.0 (d, J_SiH=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,²J_AB=13 Hz, 2H, CH₂N), 5.36 (d, J_SiH=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 C_q), 128.5 (ar CH), 128.7 (ar CH), 129.3

(ar CH), 129.6 (ar CH), 130.6 (ar C_q), 130.6 (ar C_q),

134.8 (ar C_q), 136.8 (ar CH), 138.7 (ar C_q), 139.8 (ar

C_q), 145.0 (ar C_q), 145.6 (ar C_q). 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 LiAlH₄and

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, ²J_AB=13 Hz, 4H,

CH₂N), 4.68 (d, ³J=2 Hz (d, ¹J_SiH=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, J_SiH=206 Hz), 1H, SiH),

6.99–7.17 (m, 9H, ar H), 7.59–7.64 (m, 2H, ar H), 7.88

3

1

²J_AB=7 Hz, 4H, CH₂N), 5.51 (d, J=3 Hz (d, J_SiH

=

3

1

188 Hz); 1H, SiH), 5.65 (d, J=3 Hz (d, J_SiH=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 C_q), 135.6 (ar C_q) 136.5 (ar CH), 137.6 (ar

CH), 146.7 (ar C_q). ²⁹Si-NMR (C₆D₆): l= −42.1 (dtt,

¹J_SiH=205 Hz, ²J_SiH=6 Hz, ³J_SiH=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 C_q), 135.3 (ar C_q), 136.6 (ar CH), 138.2 (ar

CH), 138.5 (ar C_q), 146.0 (ar C_q). ²⁹Si-NMR (C₆D₆):

l= −31.5 (d, ¹J_SiH=190 Hz, SiPh₂H), −42.2 (d,

¹J_SiH=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, J_SiH=186 Hz, J_SiH=6 Hz, J_SiH=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 LiAlH₄were 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 LiAlH₄in 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,

¹J_SiH=190 Hz), 1H, SiH), 5.47 (d, ³J=3 Hz (d,

¹J_SiH=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 C_q), 134.6 (ar C_q), 135.8 (ar C_q), 137.7 (ar

CH), 137.7 (ar CH), 137.9 (ar CH), 145.9 (ar C_q).

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, J_AB=13 Hz, 4H, CH₂N), 5.75, 5.86 (AB

3

system, J_AB=8 Hz, 2H, Si₂H₂), 6.65 (s, 4H, ar H),

1

²⁹Si-NMR (C₆D₆): l= −43.0 (d, J_SiH=203 Hz), −

4

6.93 (ddd, ³Jꢁ³J=7 Hz, J=1 Hz, 2H, ar H), 7.13

1

31.0 (d, J_SiH=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 C_q), 135.4

ꢀNMe₂ꢀMeꢀH], 414 (7) [M⁺ꢀAr], 297 (100) [M⁺

ꢀ(ClC₆H₄)₂SiH],

NMe₂ꢀH].

253

(100)

[M⁺ꢀ(ClC₆H₄)₂SiHꢀ

(ar C_q), 137.2 (ar CH), 138.6 (ar C_q), 145.1 (ar C_q),

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 LiAlH₄were added at

0 °C and the suspension was stirred for 45 min at r.t.

1

146.0 (ar C_q). ²⁹Si-NMR (C₆D₆): l= −41.8 (d, J_SiH

=

1

2

205 Hz, SiAr₂H), −55.7 (dd, J_SiH=178 Hz, J_SiH=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 LiAlH₄in 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/10⁻⁴torr) 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

Me), 2.98, 3.30 (AB system, J_AB=13 Hz, 2H, CH₂N),

3.22, 3.65 (AB system, J_AB=15 Hz, 4H, CH₂N), 6.63

3

5.89, 5.94 (AB system, J_AB=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

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 C_q), 137.9 (ar CH), 140.0 (ar

C_q), 144.5 (ar C_q), 147.6 (ar C_q). 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

C_q), 138.3 (ar CH), 138.5 (ar CH), 138.5 (ar CH), 138.9

(ar CH), 144.6 (2·ar C_q), 145.1 (2·ar C_q), 145.3 (ar C_q),

145.5 (2·ar C_q), 146.8 (ar C_q). ²⁹Si-NMR (C₆D₆): l= −

44.9 (d, ¹J_SiH=199 Hz, SiArMesH), −55.9 (dd,

¹J_SiH=179 Hz, ⁴J_SiH=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 C₆D₆was 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

C₆D₆was 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 C₆D₆was 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

CCl₄was 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 C₆D₆was 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 C₆D₆was 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 C₆D₆was 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 C₆D₆in 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.

[4] (a) O. Graalmann, U. Klingebiel, J. Organomet. Chem. 275

(1984) C1;

(b) H. Sohn, R.R. Huddleston, D.R. Powell, R. West, K. Oka,

X. Yonghua, J. Am. Chem. Soc. 121 (1999) 2935.

[5] See e.g.: (a) S. Masamune, Y. Kabe, S. Collins, D.J. Williams, J.

Am. Chem. Soc. 107 (1985) 5552;

(b) M. Weidenbruch, A. Pellmann, Y. Pan, S. Pohl, W. Saak, H.

Marsmann, J. Organomet. Chem. 450 (1993) 67.

[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 , z_calc=1.179 g cm⁻³, 2[ range from 4 to

,

51°, (−10=h=10, 0=k=45, 0=l=12), Mo–K_a,

u=71.073 pm, T=133 K, crystal dimensions 0.5×

0.4×0.4 mm, 33 615 reﬂections, 6039 independent

(R_int=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.

[8] P.P. Gaspar, R. West, in: Z. Rappoport, Y. Apeloig (Eds.), The

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 F²using

a full matrix least squares target (^SHELXL-97) [33]. The

2

R-values were deﬁned as R₁=[ꢀꢁꢁF_oꢁ−F_cꢁꢁ /ꢀꢁF_oꢁ and

wR₂=ꢀw(F_o²−F_c²)²/ꢀwF⁴_o]^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.

Organomet. Chem. 507 (1996) 221;

(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.

[20] E.A. Williams, in: S. Patai, Z. Rappoport (Eds.), The Chemistry

of Organosilicon Compounds, vol. 29, Wiley, Chichester, 1989,

p. 511.

[21] B.J. Helmer, R. West, R.J.P. Corriu, M. Poirier, G. Royo, A. de

Saxce, J. Organomet. Chem. 251 (1983) 295.

[22] S.G. Baxter, K. Mislow, J.F. Blount, Tetrahedron 36 (1980) 605.

[23] A. Bondi, J. Phys. Chem. 68 (1964) 441.

[24] D. Kost, I. Kalikhman, in: Z. Rappoport, Y. Apeloig (Eds.),

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.

[27] (a) R. West, S.S. Zeigler, L.M. Johnson, J. Organomet. Chem.

341 (1988) 187;

(b) D.M. Roddick, R.H. Heyn, T.D. Tilley, Organometallics 8

(1989) 324.

[28] (a) H. Gilman, D. Gorsich, J. Am. Chem. Soc. 77 (1955) 6380;

(b) H. Gilman, D. Gorsich, J. Am. Chem. Soc. 80 (1958) 1883.

[29] R. West, M.J. Fink, M.J. Michalczyk, K.J. Haller, J. Michl,

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.

[14] (a) K. Tamao, K. Nagata, M. Asahara, A, Kawachi, Y. Ito, M.

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-

bridge, 1991, p. 305.

[30] M. Weidenbruch, A. Scha¨fer, R. Rankers, J. Organomet. Chem.

(1980) 171.

[31] (a) S. Mawaziny, J. Chem. Soc. A (1970) 1641;

(b) H. So¨llradl, E. Hengge, J. Organomet. Chem. 243 (1983) 257.

[32] G.M. Sheldrick, Acta Crystallogr. A 46 (1990) 467.

[33] G.M. Sheldrick, SHELX-97, Universita¨t Go¨ttingen, Germany

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⁻¹are

necessary, whereas the dissociation energy of a disilene, which is

Article Doi

Synthesis of di- and trisilanes with potentially chelating substituents

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

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

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

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