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Crystal and Molecular Structure of Cyclooctasulfur Oxide S8O.

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i. e., a value that agrees closely with the ratio of the observed
shifts given in (6).
[8l R. Hoffmann, J. Chem. Phys. 39, 1397 (1963): R. Hoffmann and
W N . Lipscomb, ibid. 36, 2179, 3489 (1962); 37, 2872 (1972).
-
-34
16
-63
49
45
3
-104
0
0
164
147
237
-5
234
164
12
262
386
From this result the general conclusion can be drawn
that Koopmans’ theorem is not always a valid approximation, even in the form (3), i.e. as a basis for perturbation
calculations. It must fail in particular when, for example,
for symmetry reasons, the orbital Jr, that is vacated by
the electron e- in process (2) is localized only in one
part of the molecule M (cf. (8)).According to the assumptions under which Koopmans’ theorem was derived [same
SCF orbitals JIJ for M and M+(JIJ)] first a positive charge
increase described by JI: will be produced, which is necessarily localized [cf. M+(Jr,)]. The subsequent relaxation
process spreads the positive charge into the region of
Q
-e-
Relax.
+ .v;
the system where $:=O [cf. M,’(JIJ)]. The resultant charge
equalization stabilizes the radical cation (Pading’s electroneutrality rule). If M is substituted in a region where
JIj=O, then clearly one must take into account the changes
SAQn and &AQo caused by electron relaxation since they
give rise to first-order perturbations. Similar considerations
apply also to orbitals whose “localization” is not due
to symmetry, such as those of “lone pairs”. On the other
hand, the usual procedures within the framework of Koopmans’ theorem may be expected to give reasonable results
when Jr, extends more or less uniformly over the whole
molecule M.
Received. February 23, 1973 [Z 807 IE]
German version: Angew. Chem. H5, 414 (1973)
[I]
1 Koopmans, Physica I , 104 (1934).
[2] W C . Richards, Int. J. Mass Spectrom. Ion Phys. 2, 149 (1969).
[3] D. R. Lloyd and N. Lynaugh in D . E . Shirley: Electron Spectroscopy.
North Holland, Amsterdam 1972, p. 445.
[4] A. N 4 u r d . Chem. Commun. 1969, 1022, 1427.
[5] M:M. Rohmer and A VeiUard, J. C. S. Chem. Comm. 1973, 250.
[6] E . Hrilbronnrr, V. Hornung, F. H . Pinkrrton, and S . F . Thames,
Helv. Chim. Acta 55, 289 (1972): M. Klrssinger, Angew. Chem. 84. 544
(1972): Angew. Chem. internat. Edit. 1 1 , 525 (1972): R. Susrmann and
R . Schtrberr, Tetrahedron Lett. 1972, 2739: P. A. Clark, Theor. Chim.
Acta 2X. 75 (1972).
[7] E Hrilhronnrr, R Gleirrr, H . Hop% V Hornuny, and A . drMeijrre,
Helv. Chim. Acta 54. 783 (1971).
31
- 42
48
- 26
-4
74
-131
-9
188
9
229
376
[9] M J. S . Dewar and E. Haselback, 3. Amer. Chem. Soc. 92, 590
(1970); N . Bodor, M . J. S . Dewar, A . Hargrt, and E . Haselhach. ihid.
92, 3854 (1970); M . J. S . Dewar, E. Haselbach, and S . D . Worlry, Proc.
Roy. SOC.London A 315,431 (1970).
[lo] C. Fridh, L. Asbrink, and E. Lindholm, Chem. Physics Lett. 15,
282 (k972); L. Asbrmk, C. Fridh, and E . Lmdholm, ihid. 15, 567 (1972):
J . Amer. Chem. Soc. 94, 5501 (1972).
[ I l l J. A. Pople, D. L. Beueridgr, and P . A . Dobosh, J. Chem. Phys.
47, 2026 (1967).
[12] Un’published results.
Crystal and Molecular Structure of Cyclooctasulfur
Oxide, SSO[~]
By Ruff Steudel, Peter Luger, Hans Bradaczek,
and Michael Rebsch“]
S,O is formed on condensation of SOClz with “crude
sulfane” (H,S,; n = 3,4,5.. .) by the dilution technique; it
crystallizes from CS2 in yellow needled2].We have carried
out a single-crystal X-ray structure analysis of such crystals
at 10°C.
The crystals belong-to space group Pca2, with a= 13.197,
b=7.973,c=8.096A,d,,i,=2.11,de,,=2.13gcm~3. 1008
reflections with 8 between 3” and 27” were measured on
an automatic Siemens single-crystal diffractometer. 128
reflections whose intensity was less than twice the statistical
error were regarded as unobserved. As the substance
decomposed gradually the intensity measurements were
effected with three different crystals. Scaling was achieved
by a reference reflection. We determined the phases by
the tangent formula[31; the structure was refined by the
method of least squares with anisotropic temperature factors for all atoms. After convergence of all the parameters
the final R value amounted to 5.0%.
Figure I shows the result. Table 1 contains the intramolecular nuclear distances and angles. The molecule of S,O
belongs to the point group C,. The S atoms form a crownshaped ring in which each set of four atoms lies approximately in one plane. The two planes are almost parallel.
The 0 atom is in an axial position to the ring. The S-0
internuclear distance of 1.483 corresponds to the value
of 1.49 A calculated from the valence force constantr21.
[*] Prof. Dr. R. Steudel and Dr. M. Rebsch
lnstitut fur Anorganische und Analytische Chemie der
Technischen Universitat
I Berlin 12, Strasse des 17. Juni 135 (Germany)
Prof. Dr. H. Bradaczek and Dr. P Luger
lnstitut fur Kristallographie der Freien Universitat
I Berlin 33, Takustrasse 6 (Germany)
423
Table I . Bond lengths and angles in the S,O molecule. Standard deviations in parentheses.
lnternuclear distances
s10
S'SZ
S W
s3s4
s4ss
[A]
1.483 (0.009)
2.204 (0.004)
2.000 (0.005)
2.064 (0.004)
2.044 (0.005)
S5Sb
S"S7
S'SX
SXS'
Valence angles [ ]
OS'S'
OSiSH
S2S'Sn
S1S'S3
S2S'S4
106.0 (0.4)
106.3 (0.4)
101.8 (0.2)
102.3 (0.2)
108.4 (0.2)
2.047
2.071
2.006
2.200
(0.005)
(0.005)
(0.005)
(0.004)
3.066 (0.009)
3.096 (0.010)
2.976 (0.010)
2.977 (0.009)
s70
s30
s20
seo
Dihedral angles ["I
S'S4S'
S4S5Sh
S5ShS7
ShS7S8
SiSHS'
105.9 (0.2)
106.7 (0.3)
107.9 (0.2)
107.4 (0.2)
101.6 (0.2)
S'S'SJ/S2SJS'
S'S'S'/S3S4Ss
S'S4SS/S4SSSh
S4SSSh/SSShS7
94.8
102.3
107.1
98.8
S'Ss"S'/S"S'Sn
SbS'SH/S'SnSs'
S'SnSr/SXSiS2
S8SiSz/SiS'S'
93.1
101.7
1 1 1.5
102.2
[2] R. Srrudel and M. Rebsch, Angew. Chem. 84, 344 (1972): Angew.
Chem. internat. Edit. I / , 302 (1972).
[3] J . K u r l r and H . Huuprmunn. Acta Crystallogr. Y. 635 11956).
[4] J . Donohrrr in 5. M r y r r . Elemental Sulfur. Wiley-Interscience, New
York 1965, p. 13.
[5] F . Xrinstru: Structural Aspects of the Allotropy of Sulfur and the
other Divalent Elements. Waltman, Delft 1967. p. 23.
m
Fig. I . Structure of the molecule of SeO
The intramolecular S-S distances show more pronounced
variations than in the S, ring of rhombic a-sulfur where
they vary between 2.042 and 2.050A14'. Very striking are
the two unusually large S-S distances involving the
thionyl group (S'S' and S'S8: 2.20A); these S-S bonds
are to be regarded as partial bonds and their ready cleavage
probably accounts for the ease of decomposition of S 8 0
at room temperature. SO, and polymeric sulfur are
produced in this decomposition'']; elimination of SOz
can occur without diffusion or rotation of the S,O molecule
in the crystal since the packing is such that the SO groups
of molecules stacked next to and above each other form
a planar zig-zag chain:
The unit cell contains two such chains parallel to the
c-axis. Within each chain the intermolecular S-0 distance
amounts to 2.935A (van der Waals bond length: 3.2A):
the OSO and SOS angles amount to 175 and 131O, respectively. Such intermolecular interaction of the S,O molecules
was supposed previously on the basis of the IR spectrum['].
The smallest intermolecular S-S distance of 3.388 A
accords with findings for rhombic
(van der Waals
distance: 3.6
In the S,O ring the dihedral angles, much discussed in
connection with the stability of sulfur rings, vary within
relatively large limits. The mean value 101.4". however,
is only slightly greater than that (99")found for rhombic
cycIo~ctasulfur~~~.
A).
Tetrasulfur Tetranitride-A
Insertion Reagent [**I
New
By Herbert W Roesky and Michael Diet/[*]
Cleavage of silicon-nitrogen or tin-nitrogen bonds by
halides R X has proved to be a versatile synthetic procedure[" 'I, but insertion reactions with S4N, have not hitherto been reported.
We have now treated SIN (and also SnN) compounds
of type (
with tetrasulfur tetranitride (2) in the molar
ratio 2: 1, and obtained products containing an S,N, skeleton (J), e. 61.:
2 (CH,),SiNR,
( 1)
+ S4N4 +
(2)
2 (CH3),Si-N=S=N-S-NR2
/3u), R = CH, : b.p. 2 9 OC/O.Ol t o r r
(3b), R = C,H,: b.p. 3 7 OC/O.Ol t o r r
The reaction appears to involve nucleophilic attack by
the amino nitrogen on a sulfur atom of the S4N, ring,
leading to electrophilic cleavage of the metal-nitrogen
bond[,].
N-S-N
R,N:
I
II
2s:
(CH,),Si,:N-S-N
I
:",
S i ( C H3)
I
I
:S@?:NR~
/I
0
In this connection particular interest attaches to the reaction of S,N,CI, ( 4 ) with SIN compounds. For example,
if ( 4 ) is allowed to react with ( I a ) in the molar ratio
1 : 2, then S4N4 (2) is formed as intermediate.
Received. March 5, 1973 [Z XI2 I€]
German version: Angew Chem. 85. 452 (1973)
[ I ] Part 20 of Sulfur-Oxygen Compounds. This work was supported
by the Fonds der Chemischen lndustrie and the Senator fur Wirtschaft
des Landes Berlin. Part 19. R . Sfrirdrl. P. Lugrr, and H. Brudoczck.
Angew. Chem. 85. 307 (1973): Angew. Chem. internat. Edit. I2, 316
f 1973).
424
[*] Prof. Dr H. W. Roesky and DiplLChem. M. Diet1
Anorganisch-chemisches lnstitut I der L'niversitit
6 Frankfurt, Robert-Mayer-Strasse 7--9 (Germany)
[**I This work was supported by the Fonds der Chemrschen lndustrie
and the Deutsche Forschungsgemeinschaft.
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