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Bis(N N-methylsilanetriyl)tris(sulfur Diimide)ЧA Bicyclic Derivative of S4N4.

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[8] The production of ( I b ) corresponds to the formation of the 1,l-di-totbutylbenzyl radical [9].
[9] K . Schrrinrr and A. Berndt, Angew. Chem. 86, 131 (1974); Angew. Chem.
internat. Edit. 13,144 (1974).
[lo] R . W Fessenden and R. H . Schuler, J. Chem. Phys. 39, 2147 (1963).
[ l l ] D . H. Leoy and R. J . Myers, J. Chem. Phys. 41, 1062 (1964); 44, 4177
( 1966).
Bis(N, N'-methylsilanetriyl)tris(sulfur Diimide)- A
Bicyclic Derivative of S4N4[**]
By Herbert W Roesky and Hartmut Wiezer['l
The sulfur atoms of tetrasulfur tetranitride can be replaced
in part by metal atoms['I. We now report the synthesis of
a new cage compound in which two Si atoms are linked
via three SN2 bridges.
Reaction of methyltrichlorosilane with N,N'-bis(trimethy1stanny1)sulfur diimideLz1(1 ) yields an ether-soluble yellow
crystalline compound (2),
2CH3SiCI3
+ 3(CH&Sn-NSN-Sn(CHn)n
--t
(1)
Fig. 1. a) ESR spectrum of the I,l-di-terr-butyl-2-methylallylradical ( I b )
in benzene at 25'C; b) computer simulation with the coupling constants
given in the text, line width 0.04G.
stants due to spin polarization are therefore expected to be
of the order of 0.0 G for Ha and Hb. The considerably larger
experimental values of 0.96 and 3.40G must consequently
arise from another mechanism, as underlined in particular
by the exceptionallylarge ratio of 3.5 for the coupling constants
of two protons attached to the same R center C3. Coupling
constant ratios of about 1 are usually found for such protons
(ally1 radical: 14.8/13.9['01; radical anion of butadiene:
7.6/7.6" 'I).
Interpretation of the exceptionally large coupling constant
of 3.40G requires an experimentally unequivocal assignment
to Ha or Hb, which is currently in progress. Sigce the geometry
of the C3-Hb o bond relative to the p orbital of the unpaired
electron, which is important for R-o interactions, is almost
identical with that of the C-H,,,h,
o bonds of the benzyl
radical that is twisted through 90°[9],
the contribution from
R-odelocalization should be of comparable size for Hb and
Hortho.As aFrthois 0.91 or 0.82 GI9], we assign aH= 0.96 G to
Hb.The exceptionally large coupling constant a H =3.40G can
then be readily explained in terms of homohyperconjugation
in twisted R radicals[21.This interpretation is supported by
quantum mechanical approximation calculations for the conformations A and B of the n-propyl radical comparable with
( 1 ) which yield values of l.0'51, 2.OE6],or 0.2G'71 for Hb,
and 3.Oc5],3.24I6], or 4.37 GI7]for H,.
CHsSi(NSN)3SiCH3
12)
+~(CHI)~S~CI
whose composition is established by elemental analysis and
above all by its mass spectrum131.The molecular ion M +
at m/e 266 has a relative intensity of 100%; the following
fragments are also observed: 251 M-CH3 (63%), 223 MCH3Si ( 5 YO),220 M - NS (5 YO),206 M - N2S (5 %), 192 M N3S (76%), 191 CH3Si2N4S2(2Ooh),177 CH3Si2N3S2YO),
164 (CH3)2SiN3S2 (32%), 160 (CH3)2SizN3S(42%), 149
CH3SiN3S2(42 %), 146 (CH3)2Si2N2S
(~OYO),
145 CH3Si2N3S
(9Oh), 118 (CH3)'SiN2S (20%), 105? (12%), 103 CH3SiNzS
(11 Y), 102 SiN3S (IS%), 101? (20%), 85 CH3SiN3 (41 YO),
74 SiNS (22%), 70 SIN, (60%), 58 (CH,),Si (2073, 46 NS
(34%), 43 CH3Si (40%).
Received: October 29, 1973 [Z 970b IE]
German version: Angew. Chem. 86,132 (1974)
H%
'/ H
[ 11 Homohyperconjugation in Twisted x Radicals, Part 2. This work was
supported by the Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen Industrie, as well as by Deutsche Shell AG and Chemische
Werke Huh-Part 1 : [2].
[Z] A. Berndt, Tetrahedron Lett. 1969, 5251.
[3] G . A. Russell, G. V! Holland, and K. Y. Chang, J. Amer. Chem. SOC.
89, 6629 (1967); G . A. Russell in E. 7: Kaiser and L. Keuanr Radical Ions.
Wiley-Interscience, New York 1968, pp. 138-147.
[4] H . Lemaire, A . Rassat, and P. Rey, Chem. Phys. Lett. 2, 573 (1968).
[S] G . R . Underwood and R. S. Gicens, J. Amer. Chem. SOC.90, 3713 (1968).
[6] G . R . Underwood, !I L. Vogel, and J . lorio, Mol. Phys. 2 5 , 1093 (1973).
[7] Y. Ellinger, A. Rassat, R. Subra, and G. Berthier, J. Amer. Chem. SOC.
95, 2373 (1973).
146
Fig. I. Proposed structure of bis(N,N'-methylsilanetriyl)tris(sulfur diimide)
(21.
Compound (2) can be sublimed (sublimation temp. 65 'Cj0.1
torr) and melts at 95-96 "C. The 'H-NMR spectrum contains
just one signal at 6 = - 0.50 ppm (TMS as external standard).
[*] Prof. Dr. H. W. Roesky and DipLChem. H. Wiezer
Anorganisch-chemisches Institut I der Universitat
6 Frankfurt am Main, Niederurseler Hang (Germany)
['*I This work was supported by the Fonds der Chemischen lndustrie.
Angew. Chem. internat. Edit. J Vol. 13 (1974) J No. 2
The IR spectrum exhibits few bands and is suggestive of
a symmetrical molecule [tentative assignment : v,,CH 2980 w,
v,CH 2930 w, 6CH 1400 w, v,,NS 1312 vs, v,NS 1190 vs cm-' ;
the absorptions at 1270 m, 812 s, and 780 s cm- are not open
to unequivocal interpretation].
To summarize our findings we suggest a structure having
C3h symmetry for compound (2) (Fig. 1). Models show the
sulfur atoms of the eight-membered ring to have P X O - and
endo orientations and thus to be at a maximum distance
from each other. Hence strain-free bonding is possible.
'
Experimental:
A solution of CH3SiC13 (2.98g, 2mmol) in ether (50ml) is
added dropwise to a stirred solution of ( 1 ) (1 1.61 g, 3 mmol)
in ether (250ml). After refluxing for 3 h the solvent and
(CH&SnCI are removed under vacuum and the residue is
sublimed. Yield of (2): 1.1 g (44%) of yellow transparent
leaflets.
Received: November 23, 1973 [Z 971 I€]
German version: Angew. Chem. 86, 130 (1974)
[ I ] 0.J . Schrrrr and R . Wirs, Angew. Chem. 83, 882 (1971); Angew. Chem.
internat. Edit. 10, 812 (1971); H . W Rorsky and H . Wiezrr, Chem. Ztg.
Chem. App., in press.
[2] H . W RoPsky and H . W i c e r , Angew. Chem. 85, 722 (1973); Angew.
Chem. internat. Edit. 12, 674 (1973).
[3] W e are grateful to Dr. D.5iihli.r. Gottingen, for recording the spectrum.
Triphenylcyclotriphophane as a New Ligand in Transition Metal Complexes[**]
By Marianne Baudler and Manfred Bock"]
Following the synthesis of triphenylcyclotriphosphane ( I )['I,
the first establishedI2I derivative of P3H313], we have now
succeeded in incorporating this neutral[41 three-membered
phosphorus ring as a ligand into transition metal complexes.
(rl-Triphenylcyclotriphosphane)tetracarbonyliron(o)(2) and
-tricarbonylnickel(o) ( 3 ) are formed on reaction of ( I ) with
tetracarbonylirontetrahydrofuran (4)'" and tetracarbonylnickel (S), respectively.
The golden red monomeric complex (2) is readily soluble
in carbon disulfide, tetrahydrofuran, and benzene. O n heating,
carbon monoxide is liberated above 60°C before melting
occurs ( zI l O T ) . Even after a few days at -20°C transition
can already be observed to products of higher relative molecular
mass and lower solubility.
Owing to its instability, especially in dilute solution at reduced
pressure and towards Ni(CO)4, the lemon yellow complex
(3) cannot be obtained absolutely pure. It decomposes at
room temperature with grey coloration within a few hours;
even more rapid conversion with brown and black coloration
IS promoted by dissolution or warming, CO being liberated
above 60 C.
[*] Prof. Dr. M. Baudler and Dr. M. Bock
Institut fiir Anorganische Chemie der Universitat
5 Koln I,Ziilpicher Strasse 47 (Germany)
[**I
Contributions to the Chemistry of Phosphorus, Part 58. This work
was supported by the Deutsche Forschiingsgemeinschaft and the Fonds der
Chemischen 1ndustrie.-Part 57: M . Baudler and A. Zarkadas, Chem. Ber.
106. 3970 (1973).
Angrw. Chem. inturnat. Edit.
1 Vol. 13 ( 1 9 7 4 ) 1 No. 2
The 31P-NMR spectra of (2) and (3) provide unequivocal
information about the symmetry and bonding of the threemembered ring phosphorus ligand. They each display a sharp
singlet at 6 = +4.8 and + 15.8 ppm, respectively (benzene,
25 -C, 85 YOH 3 P 0 4ext.)161 not subject to splitting or broadening at low temperature (tetrahydrofuran, -70 C). The complexes are thus diamagnetic and the three phosphorus atoms
equivalent. ( I ) must therefore be bonded through the plane
of the P3 ring as a trihapto ligand17] and act as donor for
an electron pair. The upfield shift of the 31P-NMR signal
of (2) and (3) compared to that of pure ( I ) (6= +3.4 ppm"])
reveals that complex formation is associated with a weak
additional shielding of the phosphorus, which should be interpretable in terms of the acceptor properties of this ligand
leading to delocalization of electrons of the transition metalr8'.
A qualitative explanation of the bonding in (2) and ( 3 )
invokes I ) overlapping of a free metal orbital of suitable
symmetry with the doubly occupied lowest energy P3 ring
molecular orbital (C3" symmetry), formed by combination
of three P atomic orbitals, which is preferentially localized
above the plane of the ring, and 2) back-donation from an
occupied metal orbital to the corresponding antibonding unoccupied P3 ring molecular orbital. The extent to which d hybrid
components play a role in the P AOs and thus in the P,
ring MOs requires further study.
The intact cyclic structure of the phosphane ligand is confirmed
by the IR spectra of (2) and (3); their shape in the ring
vibration region 540-390 cm- is characteristic for that found
for ( 1 ) . For (2) the v C 0 vibration range contains four weilseparated bands of almost equal intensity (2043, 2012, 1975,
1940cm ') which, assuming a trigonal-bipyramidal structure,
indicate the three-membered ring ligand to have an equatorial
position (C2" symmetry). Two intense CO bands (2070,
1999cm- ') appear for ( 3 ) (C3" symmetry), which essentially
agree with those of the monophosphane complex
[Ni(C0)3P(C6H5)3][y1.
Owing to the poor thermal stability of the new complexes,
neither the molecular ion nor fragments formed by successive
removal of CO are observed in the mass spectrum; with
(2) theonly ion of significant intensity at higher mass numbers
is (C6H5P);.
(~-Triphenylc~~clotriphosphane)tetracarbonyliron(o)
(2)
Compound ( 1 ) (2.0g, 6.17mmol) in T H F (50mI) is refluxed
with a fivefold stoichiometric amount of ( 4 ) [from Fe(C0)s
(6.05g, 30.88mmol)l in T H F (150ml) with stirring for 12 h
(color change from violet-red to red-brown). After concentration to SO ml, the same amount of a freshly prepared solution
of ( 4 ) in T H F is added and the mixture heated for a further
12 h. The crude red product obtained on complete removal
of the solvent in a vacuum is dissolved in benzene (50ml)
and chromatographed' over silica gel (0.05-0.2 mm): an
unknown brown substance ( 2loo/,) which cannot be eluted
with benzene appears as residue. Removal of the solvent from
the eluate and drying in a high vacuum afford ( 2 ) as a
foamy solid having a golden-red luster; yield 2.3g (76%).
M. W. 490 (osmometric in C6H6 (45~C)).
(~?-Triphenylcyclotriphospharze)tricarbonylnickel(
0 ) (3)
Compound ( 5 ) (0.53g, 3.10mmol) is added from a one-way
syringe to a suspension of ( I ) (l.Og, 3.09mmol) in fi-pentane
(10ml) at room temperature. Liberation of CO ceases after
about 1 h. In order to avoid conversion of ( I ) into pentaphenyl-cyclopentaphosphane, stirring is performed only towards the end of the reaction and for 0.5 h after completion
of the reaction. After insoluble products ( 2 100mg) have been
147
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