Synthesis and properties of some silagermaalkanes

INORG. N U C L .

CHEM.

LETTERS

Vol. 6,

pp.

617-620,

1970.

Pergamon

Press.

Printed

in Great Britain.

SYNTHESIS AND PROPERTIES OF SOME SILAGERMAALKANES

G° A. Gibbon, Department Carnegie-Mellon

E. W. Kifer and C. H° Van Dyke

of Chemistry and The Mellon Institute University,

Pittsburgh,

Pennsylvania

15213

~Received 23 April 1970)

Compounds of the Group IV elements which contain both Si-H and Ge-H bonds are relatively rare and have not been investigated

in much detail.

As

part of a systematic study of compounds of this type, we have undertaken

the

synthesis

of several new silagermaalkanes.

The general direction of forthcom-

ing investigations will be to ascertain the relative chemical behavior of the Si-H and Ge-H bonds when both are present in the same molecule. line, we have investigated

Along this

the reaction of GeH3CH2SiH 3 with hydrogen chloride

in the presence of aluminum chloride. Results and Discussion The synthesis of l-sila-3-germapropane,

SiH3CH2GeH 3 (yield: 35%, extrap

olated b.p. = 30 = , m.p. = -134.8 + 0.2 = ) has been accomplished by the reaction of CICH2SiH 3 with solid NaGeH 3.

The compound

is reasonably stable thermally

and can be manipulated without any noticeable decomposition system operations.

It quantitatively

condenses

thus can easily be purified by low-temperature l-germa-2-silapropane,

GeH3SiH2CH3,

in normal vacuum

in a trap cooled to -i12 ° and vacuum fractionation

techniques.

has been prepared in low yields

(<5%) by the interaction of CH3SiH2CI with KGeH 3 in hexamethylphosphortriamide (HMPT).

The compound is difficult

ation techniques

and the characterized

phase chromatography.

to purify by low temperature

fraction-

sample used was purified by vapor

The compound is much less thermally stable than the

isomeric SiH3CH2GeH 3 . 617

618

SILAGERMAALKANES

Vol, 6, N,~}. 7

The Si-H bonds of SiH3CH2GeH 3 are readily chlorinated by hydrogen chloride in the presence of aluminum chloride. in which the Ge-H bonds underwent halogenation.

No compounds were observed The isolated products of the

reaction included GeH3CH2SiH2CI , (h.p. 104 ° , m.p. -129.2 ~ 0.2 ° ) GeH3CH2SiHCI 2 (vapor pressure at O °, 3.7 torr) and the unexpected product 1,5-disila3-germapentane S i H 3 C H 2 G e H 2 C ~ S i H 3 (vapor pressure at O °, 8.6 torr).

Germane

was also formed in the reaction, and the most likely reaction which accounts for the formation of SiH3CH2GeH2CH2SiH 3 is the following:

2SiH3CH2GeH 3

>

(SiH3CH2)2GeH 2 + GeH 4

The proton nmr spectra for the compounds can be readily analyzed in terms of first order coupling.

Data obtained are summarized in Table I.

The

chemical shifts of the Si-H and Ge-H protons in most of the known silanes and germanes fall in the same general vicinity.

For all the compounds reported

herein (except for GeH3CH2SiH3) the two absorptions can be unambiguously assigned on the basis of relative intensity measurements.

The low resolution

scan of GeH3CH2SiH 3 actually has the two 1:2:1 triplet absorptions for the Ge-H and Si-H protons combined to give a 1:3:3:1 quartet absorption.

(The

Si-H and Ge-H chemical shift difference is about the same order of magnitude as the H-H coupling constants).

The triplet for the Si-H protons can be

unambiguously assigned by examining the 29Si satellites in the spectrum. These are two low intensity triplets (29Si: 5% abundant, I = 1/2) symmletrically disposed about the low field triplet of the combined triplets.

NMII

data will be discussed in more detail when additional compounds of this type are prepared and studied.

Experimental Standard vacuum line techniques were employed throughout.

Starting

materials were prepared by methods described in the following references: CICH2SiH3(1) , CH3SiH2CI (2), NaGeH3(3) , and KGeH 3 in HMPT (4).

6.17 5.22 4.47 6.02

9.71

9.60

9.36

9.98

GeH3SiH2CH 3

GeH3CH2SiH2CI

GeH3CH2SiHCI 2

(SiH3CH2)2GeH 2

6.31

6.30

6.35

7.03

6.37

T Ge-H

4.6

1.9

3.9

~.8

4.5

vic J(H,H)sIH"_cH(Hz)

3.7

3.9

3.9

-- C

4.0

vic J(H,H)GeH_CH(HZ )

c vic J(H,H)GeH_Si H = 3.6 Hz

bLong range J(H,H)siH_GeH = 0.5 Hz

285.0

234.0

198.7

J29si_H (Hz)

aCyclohexane used as solvent and internal standard; concentration %10-20%.

6.29

i0.01

C-H

T Si-H

GeH3CH2SiH3 b

Compound

PROTON NMR DATA FOR SOME SILAGERMAALKANES a

TABLE I

620

SILAGERMAALKANES

Vol. 6, No. 7

The reaction of solid NaGeH 3 with CICH2SiH 3 was carried out at room temperature for 15 min.

The reaction of KGeH 3 in HMPT with CH3SiH2CI

was carried out at 0 ° for 5 min. The reaction of GeH3CH2SiH 3 with HCI was carried out in the vapor phase for 24 hr.

The best yield of GeH3CH2SiH2CI , (66%), was obtained by

using a 5:2 molar ratio of reactants (deficit of HCI).

The best

yield of GeH3CH2SiHCI 2 (36%) was obtained using approximately equimolar quantities of reactants.

The formation of small quantities of SiH3CH2GeH2CH2SiH 3

was observed in all the experiments and it is of interest to note that the compound was not produced on treating SiH3CH2GeH 3 with HCI or o~ICI3 separately. The purity of the new compounds prepared in this wCrk has been confirmed by vapor phase chromatography.

The identity of the compounds has been

verified by mass spectral, nuclear magnetic resonance (nmr), infrared, and for SiH3CH2GeH 3 analytical data.

Acknowledsments This work was partially supported by the National Science Foundation through grant GP 12833.

E.W.K. gratefully acknowledges a predoctorNl fellow-

ship from NASA.

References i.

H. D. Kaesz and F. G. A. Stone, J.Chem.Soc., 1433 (1957).

2.

A. Stock and C. Somieski, Ber., 52, 695 (1919).

3.

C.A.

4.

S. Cradock, G. A. Gibbon and C. H. Van Dyke, Inorg. Chem. 6, 1751 (1967).

Kraus and E. S. Carney, J.Am.Chem.Soc., 56, 765 (1934).