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closo-Tetrakis(phenylstannylphosphine) an Organostannylphosphine with a Cubane Structure.

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Attempts to obtain such cyclic organostannylphosphines in
an unambiguous manner from diorganotin dichlorides and
phenylphosphine with thermal removal of HCI were unsuccesful until the following procedure was used: dimethyl-,
dibutyl-, or diphenyl-tin dichloride and phenylphosphine are
added (simultaneously at room temperature under nitrogen,
during 2 h) to a benzene solution of triethylamine present in
stoichiometric amount to act as complex-former and HCIacceptor; this method, which accords with the dilution
principle, leads to polymeric and trimeric ( I ) diorganostannylphenylphosphines.
R
I
1-1-1-
(InJ
(1bl
llcl
1
H
I
I
CH,
C4Hq
CaHx
73
:i
1
I
I
134
?::--I60
I
388, 365, 318, 310, 284
388, 347, 307, 298, 289
372, 361, 335, 308, 297
Triethylammonium chloride and insoluble polymers are
filtered off and the filtrate is concentrated in a vacuum, the
products ( I ) being then precipitated o n addition of pentane,
and recrystallized from hot methylcyclohexane. They were
shown to be homogeneous by thin-layer chromatography
under argon [31. Structures were proved by complete elemental analysis, cryoscopic determination of molecular
weight, and I R and IH-NMR spectroscopy. In the IR spectra the vibrations due to alkyl and phenyl groups attached to
tin and phosphorus were accompanied in all cases by five
bands that are assigned to the Sn-P stretching vibrations.
I n accord with observations for dialkylsilicon sulfide 141 this
indicates a chair form of the ring skeleton, having symmetry
C, and analogous to that for cyclohexane. The 1H-NMR
spectrumc5l of ( f a ) contains, as well as the multiplet of
phenyl protons, the expected triplet for the protons of the
two methyl groups bound t o tin, namely at 6 = 398.5 H z
(JlH-C-sn-31P
= 4.4 HZ, JIH-C-117Sn
46.5 HZ,
JIH-C-IIPSn
= 51.5 HZ).
( l a ) is not very stable thermally: it decomposes above 175 O C
into stoichiometric amounts of pentaphenylcyclopentaphosphane, bis(trimethylstannyl)phenylphosphine, and tin:
closo-Tetrakis(phenylstannylphosphine),
an Organostannylphosphine with a
Cubane Structure[**1
By H. Schumann and H. Benda * I
Among the oxidation products of the organostannyl phosphines formed on reaction of tetraphenyltin with phosphorus
(P4) in a sealed tube at 3OO0C we have found a polymeric
organotin phosphate that was apparently formed from a
polymeric phenylstannylphosphine (C6HsSnP)n (11. The lastmentioned compound was not isolated under the conditions
used at the time; it is also formed from anhydrous tin(I1)
chloride and diphenylphosphinolithium but this reaction is
also not readily reproducible and its course is not clarified[2l:
We have now determined the structure of this organostannylphosphine by a clear synthesis.
If benzene solutions of phenyltin trichloride and triethylamine are added simultaneously under argon to benzene into
which phosphine is being passed, the red solution obtained
contains a resinous brown precipitate of triethylammonium
chloride and polymeric products. These materials are removed, the filtrate is concentrated and freed from newly precipitated polymers, then methylcyclohexane is added; this leads
to a yellow precipitate from which fractional precipitation
by pentane affords tetrameric phenylstannylphosphine (1) in
ca. 10% yield.
Compound ( I ) decomposes above 160 "C (blackening)
without melting; it cannot be kept for long, even in an inert
atmosphere; it is largely polymerized to insoluble products
even after two days. The homogeneous condition of the
freshly prepared material is proved by thin-layer chromatography [31. Complete elemental analyses, cryoscopic determinations of molecular weight, and the IR spectrum containing few lines indicate unambiguously that it has a cubane
structure. In the infrared spectrum (Nujol) the vibrations of
A
the phenyl groups bound to tin are accompanied by essen5 [(CH~)ZS~-PC
+
~H~~
only the Sn-P stretching vibration required for Td
2 [C~HSPIS 5 [ ( C H ~ ) ~ S ~ ] Z P5Sn
C ~ H ~ -tially
~
(10)
symmetry at 328 cm-1. The two infrared-active deformation
Ethereal hydrogen chloride cleaves ( l a ) , ( l b ) , and ( I c ) with
bands lie in the longer-wavelength and no longer measurable
liberation of phenylphosphine and formation of dimethyl-,
region.
dibutyl-, and diphenyl-tin dichloride, respectively, which also
The reaction of methyl- or butyl-tin trichloride with phosproves the constitutions.
phine leads, however, like that of methyl-, butyl-, or phenylReceived: June 27, 1968
[Z 844a IE]
tin trichloride with sodium phosphide in benzene, only to
German version: Angew. Chem. 80, 845 (1968)
insoluble polymeric compounds.
[*] Doz. Dr. H. Schumann and Dip1.-Chem. H. Benda
Received: June 27, 1968
[ Z 844b IE]
Institut fur Anorganische Chemie der Universitat
German version: Angew. Chem. 80, 846 (1968)
87 Wiirzburg, Rontgenring 11 (Germany)
[**I This work was supported by the Deutsche Forschungsge[*] Doz. Dr. H. Schumann and Dip1.-Chem. H. Benda
meinschaft and the Fonds der Chemischen Industrie.
Institut fur Anorganische Chemie der Universitat
87 Wiirzburg, Rontgenring 11 (Germany)
[l] H . Schumann, H . Kopf, and Max Schmidt, Chem. Ber. 97,
1458 (1964).
[**I This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.
[21 H. Schumann, H. Kopf, and Max Schmidt, Chem. Ber. 97,
2395 (1964).
111 H. Schumann, H. Kopf, and Max Schmidt, Chem. Ber. 97,
1458 (1964).
I31 MN-Polygram Cel 300/UV 254, Macherey-Nagel & Co.;
methyIcyclohexane/benzene as mobile phase.
[2] H. Schumann, H . Kopf, and Max Schmidt, Chem. Ber. 97,
2395 (1964).
[4] H . Kriegsmann and H. Claus, Z . anorg. allgem. Chem. 300,
210 (1959).
131 MN-Polygram Cel 300/UV 254, Macherey-Nagel & Co.,
methylcyclohexane/benzene as mobile phase.
[5] 5y0 solution in benzene with benzene as internal standard.
+
Angew. Chern. internat. Edit. / Vol. 7 (1968) / No. I 0
813
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phenylstannylphosphine, organostannylphosphine, structure, closs, cubana, tetrakis
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