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Lithium Derivatives of Silanol and Related Compounds.

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The formation of ( I ) from SOCI, and NH3 can be interpreted by a series of successive condensations with elimination of HCI, H 2 0 and NH3:
2 SOClz
+ 7 NH3
2 HN(SONH,)z
NH3
H,O
HN(SONHz)z + 4 NH,CI
+ 3 HzO
NH,[S,N,O]
Received: November 21, 1972 [Z 773 IE]
German version: Angew. Chem. 85, 307 (1973)
Fig. I . Structure of the anion C,N,O
Thus the cation is not tetrahedral but instead is strongly
deformed (three different NTH nuclear separations, HNH
angles between 82 and 128').
Lithium Derivatives of Silanol
and Related Compounds
By Stephen Crudock, Evelyn A . I/: Ebsworth,
Hans Moretto, David W H . Rankin, and
W John Savage[']
Although disilylphosphane is relatively stable in vacuo,
silanethiol and silaneselenol afie hot, while silanol is not
known[']. Alkali metal derivatives of these compounds
are therefore difficult to obtain directly.
The structure of the anion can be formally derived from
the cage of S4NJ3], one S atom (S') carrying an 0 atom
and bridged to a neighboring S atom ( S 3 ) through an
N atom. This oxidized S atom is almost tetrahedrally
coordinated. The S=O nuclear separation, 1.433A, corresponds to that in other molecules with S=O double bonds
(SO, 1.42A; SOF, 1.42A).
Table 1. Bond lengths and angles in NH,[S,N,O]
We find that methyllithium reacts smoothly in diethyl
ether over a period of minutes at 227K with (SiH,),Y
(Y =0,S, Se)['] or (SiH,),Z (Z=P, As); methylsilane is
evolved in about 90% of the amount required by the
equations:
(SiH3)2Y+ CH,Li,
(SiH3),Z + CH,Li
+
+
Li[YSiH3] + CH,SiH3
L ~ [ Z ( S I H , ) ~ ] CH,SiH,
+
( I ) . Standard deviations in parenthesis
Bond tengths [A]
N4-H'
N4-H2
N4-H3
N2...H2
0 ... H '
Bond angles
0
~
1
~
1.03 (0.06)
0.98 (0.06)
0.93 (0.1 2)
2.00 (0.06)
1 95 (0.06)
S'-0
S'-N'
S'-N1
S2-N'
S2-N'
S'-N2
S'-N'
1.433 (0.004)
1.580 (0.004)
1.591 (0.003)
1.631 (0.004)
1.603 (0.003)
1.651 (0.004)
1 658 (0.005)
108.7 (0.2)
110.4.(0.2)
111.2 (0.1)
105.0 (0.2)
1 11.2 (0.2)
NiSzN2
S2N2S3
S'N3S3
N3S3N2
N2S3Nz
111.7 (0.2)
114.8 (0.2)
114.1 (0.3)
107.5 (0 2)
98.8 (0.2)
N'-N'
NI-N'
N2-N2
2.633 (0.001)
2.71 7 (0.002)
2.658 (0.001)
2.741 (0.001)
2.676 (0.004)
2.524 (0.004)
2.506 (0.005)
HLN4H2
H'N4H3
H2N4H2
HZN4H3
119(5)
85 (7)
82 ( 5 )
128 (5)
S2-SZ
S'-S3
S'-S2
s2-S'
['I
3
OSIN1
N'S1N3
N'S'N'
SIN'S2
The S-N nuclear separations in S4NsO- are somewhat
more strongly differentiated than in S,N,, where they
vary only between 1.596 and 1.634A. Nevertheless one
must assume largely delocalized n-bonds within the S4NS
skeleton. The structural formula above can therefore be
described only as a limiting structure.
As in S,N,, the contacts between the S atoms of one
cage, being 2.7& are appreciably smaller than the van
der Waals S-S separations which are 3.7 The smallest
distances between different anions are practically in agreement with the van der Waals distances.
A.
[ I ] Part 19 of Sulfur-Oxygen Compounds.-Pdrt 18: R. Srerrdei and
M . Rebxh. Angew. Chem. X4. 344 (1972); Angew. Chem. internat. Edit.
I I . 302 ( 1972).
[2] R. Sfeudrl, Z. Naturforsch. 24 b. 934 (1969).
[3] 5. D. Shormu and J . Doiiohur, Acta Crystallogr. 16, 891 (1963)
A i q e n . Clieiii.
I I I ~ C ~ I I UEdit.
I.
Wi/.
I2 (1973)
No. 4
The lithium derivatives may be isolated as white crystalline
solids by evaporation of the solvent. They have been characterized by their Raman spectra (obtained from solids
and from solutions-Tables 1 and 2).
Table 1. Rarnan spectra (cm- I ) of lithium silyl sulfide and lithium silyl
selenide Li[YSiH,] In diethyl ether.
Y =s
2130 m, p
945 w (br), d p
655 vw (br), d p
565 s, p
Y =Se
Assignment
2118
940
624
429
v,SiH
GSiH,
pSiH3
VSI -Y
m, p
w (br), d p
vw (br), d p
vs, p
[*] Prof. Dr. E. A. V. Ebsworth, Dr. S . Crddock. Dr. H. Moretto,
Dr. D. W. H. Rankin, and Dr. W. J . Savage
Department of Chemistry, Edinburgh University
West Mains Road, Edinburgh E H 9 3JJ (Scotland)
317
Table 2. Raman spectra (cm-') of lithium d~silylphosphide and lithium
disilyl arsenide Li[Z(SiH,),] in diethyl ether.
Z=P
Z=As
Assignment
2 105 m, p
940 w (br), d p
635 vw (br), d p
495 m, d p
470 s, p
145 w, p?
2 110 m, p
930 m (br), d p
580 w (br), d p
v,SiH
GSiEI,
pSiH,
v,,Si,Z
-
374 vs, p
122 w, p?
( 3 ) , whereas the corresponding open-chain model compounds react very slowly or not at all even in the presence
of silver salts. If the P-carbon atom of the vinyl compound
is itself part of a cyclopropane ring, then a reactive system
is again obtained which affords the vinyl cation ( 4 ) by
ionization['! Owing to their rigid geometry, cations of
structure ( 4 ) are characterized by particularly favorable
conditions for overlap between the vacant p-orbital and
the cyclopropane
V,S12Z
6S1,Z
The 'H-NMR spectra in general give the expected single
SiH resonance, with satellites due to "Si in natural abundance r ' J ( 2 9 S i H ) ~ 2 0 Hz
0 in all cases]; we have shown
by heteronuclear decoupling that in Li(YSiH,) the 29Si
spectrum is the expected quartet of sharp lines, whereas
in Li[Z(SiH,),] the 29Si spectrum is a quartet of quartets,
the smaller splitting arising from ,J(SiH). When Z=P,
the main SiH resonance appears as a doublet at room
temperature ['J(PH)= 15.5 Hz] and heteronuclear
decoupling shows that the 3 1 Pspectrum is a heptet. When
Y =Se, satellites due to "Se appear at low temperatures
['J(SeH)= 11 Hz]; they collapse at temperatures above
273 K, presumably because of some exchange process, but
at 253 K the 77Se spectrum is a quartet.
(I),
(2).
x = c1
x=I
(3)
(41
We have been able to combine the stabilizing effects of
two cyclopropane rings. We synthesized (I-bromo-l-cyclopropylm$hylene)cyclopropane ( 5 ) ; the vinyl cation (6)
derived therefrom is remarkably stable, as was shown by
the rates of hydrolysis of ( 5 ) and product analysis.
Solutions of Li(SSiH,) and of Li(SeSiH,) react with
trimethylchlorosilane to form H,SiSSi(CH,),
and
H ,SiSeSi(CH ,), respectively, which were characterized by
their vibrational spectra. We are exploring further the
synthetic potential of the lithium salts.
The kinetics of solvolysis of ( 5 ) were determined for 50%
and 80% ethanolic solutions at several temperatures and
pH values (Table l)Ib1.The main product ( > 80%) of solvolysis was dicyclopropyl ketone (7).
Received. December 11, 1972 [Z 776 IE]
German version: Angew. Chem. 85,344 (19731
The data in Table 1 show conclusively that solvolysis
of ( 5 ) occurs by an SN1 mechanism and thus involves
the intermediate vinyl cation (6):fS) reacts faster in
a solvent of higher ionizing power; the Winstein-Grunwald
rn valuef7]of 0.89 (determined from the rate constants
[ I ] C . G/idrn,e//,D. W H. Rankin, and G . M . Skrldrick, Trans. Faraday
SOC.65, 1409 (1969).
[2] S. Cradock, E. A. T/: Ebswortk, and H. F. Jessep, J. C. S . Dalton
1972. 359.
Table 1. Rate of solvolysis of (5) in aqueous ethanol
Ethanol
concn. [%]
TC- CI
PH
50
29.90 f 0.2 1
48.76i0.12
67.30k0.05
67.35 f0.08
67.34 fO.08
100.0 [a]
6.50
6.50
6.50
8.00
9.30
80
48.80 f0.10
74.41 f0.14
6.50
6.50
'1
AH+
[kcal/mol]
AS*
[cal mol
0.232 f0.002
1.82 k0.03
9.94 fO.02
10.3 k0.04
11.0 i0.007
146
20.0
-
0.0619 5 0.0003
0.744 fO.008
21.0
- 10.7
1O'k [s-
' deg- '1
7.1
[a] Extrapolated.
Synthesis and Solvolysis of (1-Bromo-1-cyclopropylmethylenek clopropane: A Particularly Stable Vinyl
Cation"I Y*lY
By William E. Hryd and Michael Hanack"]
Formation of vinyl cations on solvolysis of vinyl halides
is particularly favored by cyclopropyl groups in the cc-position'']; for example, the chloride ( 1 ) f 3 ] and the iodide
(.?)I4] are readily solvolyzed to the intermediate cation
[*I
Dr. W. E. Heyd and Prof. Dr. M. Hanack
Institut fur Organische Chemie der Universitit
66 Saarbrucken (Germany)
[**I This work was supported by the Stiftung Volkswagenwerk. W.
E. H. thanks the Stiftung Volkswagenwerk for a grant.
318
at 48.80 and 48.76"C) is one of the highest yet found
for solvolysis of vinyl halidesIzl.
The special additional stabilizing effect of the cyclopropane
ring in (6) is shown by comparison of the relative rates
of solvolysis of ( 5 ) and the vinyl bromides ( 8 a ) and
( 8 b ) (80% ethanol, 100"C[l.'l): ( 8 a j k,,,=l; ( 8 b )
kr,,=3.6x lo3; ( 5 ) k,,,=1.51 x 10'.
b'ir
(8a). R = H
( S b ) , R = CsH,
The high stability of (6) is shown also by the fact that
it has almost no tendency to rearrange. Whereas solvolysis
A n g n t . Chem. inrernac. Edit. / Vol. 12 ( I Y 7 3 ) / No. 4
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