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Complexes of Organotin Compounds with Aluminum Halides.

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silver chloride reference electrode [3]. T h e potentials increase
considerably with increasing cyanation (Table 1).
phenol. Oxidation of this gave the dimer containing cu.
55 atom-"<; of 1 8 0 . The displacement of the infrared absorption bands (Table 1 ) demonstrates conclusively that the
Table I . Half-wave potentials
Compound
M.p. [ T I
Color of
radical
2,4,6-TriphenyIphenol [4]
4-Cyano2,6-diphenylphenol
2-Cyano4,6-diphenylphenol
2.6-Dicyano4-phenylphenol
2,4,6-Tricyanophenol
149-150
red
165-166.5
green
138- I39
red
215 (decomp.)
185 (decomp.)
blue
if,
R
5
I01
Received, March 24th, 1964 IZ 707/532 IE]
Publication deferred until n o w at the authors' request
German version: Angew. Chem. 76, 433 (1964)
[ I ] D . Schminke, Ph. D. Thesis, Universitat Marburg, 1961.
[2] The preliminary stages were investigated by K . Schromm,
Marburg.
[3] F. W. Steuher, Ph. D. Thesis, Universitat Marburg, 1963; F.
W. Steuber and K . Dimroth, Tagung fur moderne elektrochemische Analysenmethoden, Eisenach, April 1964.
[4] K . Dimrofh, F. Kalk, R. Self, and K. SchlBmer, Liebigs Ann.
Chem. 624, 51 (1959).
[ 5 ] F. Bcr, Marburg.
The Constitution of the Dimer of
2,4,6-Triphenylphenoxyl
By Prof. Dr. K. Dimroth a n d Dipl.-Chem. A. Berndt
R
I1
,
R
101
Table I. Characteristic absorption bands of dimeric [IbOl- and [l*O]2,4,6-triphenylphenoxyl ( 1 ) (approximately 5 5 atom- % ' 8 0 ) in CCI:.
1665
1642
1201
958 '
1665
1642
I620
I597
1185
956
45
45
16
7
T h e quinol structure ( I ) is thus demonstrated. T h e o-quinol
structure is not disproved by the above experiments, but
seems less likely. Scission of the C - - - 0bond of ( 1 ) in solution
t o form the radical, i.e. dissociation of the dimer ( I ) , requires
only a very small energy of activation.
T h e present results are confirmed by a n X-ray analysis of
dimeric 3-bromo-2,4,6-triphenylphenoxyl;
this work shows
in addition that the product in question is a p-quinol derivative [ 6 ] .
Received, March 24th, 1964
[Z 708/5?9 1El
Publication deferred until now at the authors' request
German version: Angew. Chern. 76, 434 (1964)
Dedicated to Professor H . Meerwein
on the occnsiorz of his 85th birthday
~
2,4,6-TriphenylphenoI is readily dehydrogenated t o a red
free radical, which is perfectly stable towards oxygen [ I ] a n d
which crystallizes as a colorless dimer. I n solution, the dimer
dissociates partly into 2,4,6-triphenylphenoxyl radicals (dissociation constant i n benzene: 4x 10-5 a t 20"C, heat of dissociation: ca. 10 kcal/mole). Equilibrium between the colorless dimer a n d red monomer is reached so quickly that
solutions of the former may be readily a n d without retardation redox-titrated, e . g . by using a solution of hydroquinone.
Introduction of large substituents (bromine or one or two
phenyl groups) into the central nucleus of triphenylphenol
displaces the position of equilibrium considerably in favor
of the dimerand reduces the speedwithwhich this equilibrium
is attained. These observations cast some doubt o n the
validity of formula ( I ) for the dimer. Although the infrared
spectrum of the dimer has a doublet at 1665 and 1642 cm-1,
which may be ascribed t o t h e C=O vibrations of a quinol [2],
the result would also agree with the presence of a diquinol
(2). A band a t 958 cm-1, i . e . in the region of -0-0- absorption, suggests a diphenyl peroxide structure ( 3 ) [3].
Formulation of the dimer as a n ion pair [4]is incorrect, since
neither the anion nor the cation [ 5 ] absorb in the region of the
doublet.
By reaction of 2,4,6-triphenylbenzenediazoniumfluoroborate
with CH3'8OH [*] and cleavage of t h e resulting methyl ether
with pyridinium chloride, we obtained [180]-2,4,6-triphenyIVoI. 3 (1964)
I
doublet at 1665 and 1642 cm-1 originates from a C - 0 L i b r a tion. T h e peroxide structure (3) is thus eliminated, all the
more so a s the band at 958 cm-1 is not significantly displaced.
T h e occurrence of a shift in the ether region excludes structure (2).
Chemisches Institut
der Universitat Marburg/Lahn (Germany)
/
I
R
-
These results show that for stabilization phenoxyl radicals
need not necessarily have bulky substituents a t the 2-, 4-, a n d
6-positions. All the radicals were characterized by ESR
measurements [5].
Arigew. Chem. iriternat. Edit.
R8R
/ No. 5
~-
[ I ] K . Dimroth, F. Kalk, R . Sell, and K . Schlomer, Liebigs A n n .
Chem. 624, 5 1 f 1959).
[ 2 ] E. Miiller, K. Le,v, and G. Scltlechte, Chern. Ber. 90, 2660
(1957).
[3] S t . Goldschmidt and Ch. Steigerwold, Liebigs Ann. Chern.
438, 202 ( 1 924).
[4] E. Miillcr, K. Ley, and W . Schntidhuber, Chem. Ber. 89, 1738
( 1 9 5 6).
[ 5 ] W. Umbnch, Ph. D. Thesis, Universitat Marburg, 1962.
[6] R . .4/lmonfi, personal communication.
["I We wish to thank Prof. D. Sasluel, Rehovoth, Israel, for t h c
labelled methanol.
Complexes of Organotin Compounds with
Aluminum Halides
By Priv.-Doz. Dr. W. P. Neumann,
Dipl.-Chem. R. Schick [ I ] , a n d Dr. R . Koster
Chemisches lnstitut der Universitlt GieBen and
Max-Planck-Institut fur Kohlenforschung,
Miilheim/Ruhr (Germany)
In carrying o u t alkylations o n tin, Kvstrr [2] obtained in 1955
the crystalline complexes ( 3 ) and (7). U p t o then, only
compounds of organotin halides with Lewis bases were
known [3]. In preparing starting materials such as tin tetraalkyls, we came again across these complexes [4,5].
385
Solutions of these compounds (0.1 mole/l) in benzene a n d
nitrobenzene at 35 "C displayed relatively high conductivities: in the case of ( 3 ) we obtained 33x 10-4 and 86x 10-1
mho/cm2; for (7) we found 0 . 3 ~
10-4 and 2 . 9 ~
10-1 mho/cm2.
This suggests the formulae [R3Sn]+[AIC14]- for ( 3 ) and
[R2SnCI]+[AIC14]- for (7), at least as equilibrium states [ 6 ] .
On heating equimolar amounts of organotin halide and
aluminum halide t o 90-100°C (clear melt) for a short
period, followed by cooling and recrystallization from benzene, we obtained the colorless compounds listed in Table 1,
mostly in the form of well-shaped crystal needles. As these
substances are extremely sensitive t o moisture, careful exclusion of air (argon) is essential.
Table I .
Melting points and cryoscopic data of compounds ( l ) - ( Y )
Mean particle weight [a] p x
ComDound
at a concentration [mole/l] of
0.01
91
Ill
23
49
90
73
84
72
55
I
0.02
I
0.04
1 0.06 I 0.08
1.04
1.40
_.
-.
-
-
-
-
1.52
1.03
0.98
0.93
0.94
0.96
0.96
2.48
3.50
1.31
-
1.09
0.95
0.92
0.91
0.92
0.94
-
1.15
1.37
0.97
-
1.00
0.98
1.01
-
0.10
1.06
I .05
[a] Determined cryoscopically in benzene.
When ( 3 ) and (7) are subjected t o mild alcoholysis n o gas is
evolved; the compounds d o therefore not contain alkyl
groups bound t o aluminum. Prolonged heating of (3) o n the
other hand leads t o the formation of a small amount of
(C2H5)AICIz.
Trialkyltin halide is a stronger complexing agent than dialkyltin halide. Thus, heating of (7) with a n equimolar
amount of(CzH5)3SnCI causes displacement of (C2H&SnC12
which can be distilled off at a vacuum of 11 m m Hg, leaving
(3) behind. A complex of (CzH5)SnC13 with A1C13 could not
be isolated. At 90"C, C ~ H S C Iis rapidly given off by the
mixture, leaving SnClz behind. I n contradiction with 0th r
reports [6], we did not observe the formation of stable
complexes between tin tetraalkyls and AICI3
The mean particle weight of the dialkyltin dihalide complexes
(6)-(9) in benzene undergoes little change with the concentration; they dissociate t o a slight extent (Table 1). The
symmetrical Sn-C vibration in the infrared spectrum of
dimethyltin dibromide a t 514 cm-1 splits into two absorptions
of approximately half the intensity, occurring at 508 and
521 cni-1, when the complex (6) is formed (suspension in
nujol).
T h e mean particle weight of the trialkyltin halide complexes
( I ) and ( 3 ) - ( 5 ) in benzene, on the other hand, is very
sensitive t o changes in concentration (Table 1); association
takes place. In the infrared spectrum of (2) the symmetrical
Sn-C vibration at 512 cm-1 weakens (as compared with the
asymmetric vibration a t 543 cm-1) when the concentration in
benzene is increased a n d disappears in the solid state (suspension in nujol). Thus, in the polymer, the (CH3)sSn group is
386
completely or a t least nearly planar: there is penta-coordination around the tin a t o m :
1:
c1
1'
c1
---Sn---CIAlCl---Sn---ClAlCl--c1
c1
O n the basis of the results of particle-weight determinations
this probably applies also t o the trialkyltin halide complexes
( I ) and ( 3 ) -(5). Analogous structures have been proved or
assumed for trialkyltin acylates [7], amides [8] a n d fluoro
salts [9].
Received, March 24th, 1964
[Z 705/536 I€]
German version: Angew. Chern. 76. 379 (1964)
[I] Cf. R. Schick, Diploma Thcsis, I'niversitiit GieBen, 1962
[2] R . Kuster, quoted in [5] and in H. Zeiss: Organometallic
Chemistry. Reinhold, New York 1960, p. 247.
[3] Summary cf. R . K. Inqhnm, S . D. Rosepiberg, and H . Gilntnn,
Chem. Reviews 60, 459 (1960).
[41 W. P . Nerr n7nn, Liebigs Ann. Chcm. 653, 157 (1962).
[51 Cf. W . P . Nrnwonn, Angew. Chem. 7 5 , 225 (1963); Angew.
Chem. internat. Edit. 2, 165 (1963).
[6] 0.A . Osi!nov and 0 . E. Kushireninov, Zh. obshchei Khim. -32,
1717 (1962), mixed ethyltin chlorides with AICI3 in benzene and
concluded from physical data (without isolating any substance)
that I : I-complexes are present; they assumed hexa-coordination
around the tin atom. The solutions in benzene are reported to
possess no conductivity.
[7] M. J . Jtmssen, J . G. A . Liiijten, and G. J . M.van deer Kerk,
Recueil Trav. chim. Pays-Bas 82, 90 (1963), where further
references are given; R . Okawnro and M . Ohoru, Bull. chem.
SOC.Japan 36, 623 ( I 963).
[ S ] M. J . Jnnssei?, J . G. A . Luijten, and G. J . M. vnll der Kerk, J .
organometal. Chcm. I . 286 (1964), where further references arc
given.
[9] B. J . H n t h n w y and D. E. Websler, Proc. chem. SOC.(London)
1963, 14; H. C. Clark and R . J . O'Brien, ibid. 1963, 113; Inorg.
Chem. 2, lOZO(1963).
The Metabolism of cis-f!,,y-Enoyl-Coenzyme A
Compounds
By Doz. Dr. W. Stoffel, Dipl.-Chem. R. Ditzer, and
Dipl.-Chem. H. Caesar
Physiologisch-Chemisches Institut
der Universitat Koln (Germany)
Coenzyme A derivatives of cis-$,><- or cis-r$-unsat urated
fatty acids are formed in the course of the $-oxidation of
mono- and polyunsaturated fatty acids with cis-olefinic double
bonds. W e have investigated the further metabolism of the
cis-$,y-enoyl-CoA compounds, using cis-3-dodecenoyl-CoA
( I ) as a n example. This compound is formed in the $oxidation of oleic acid.
Contrary t o earlier reports [ I --31crotonase does not hydrate
( I ) . Instead, a cis-P,y-enoyl hydrase isolated from liver
mitochondria catalyses this reaction. The product is D-(-)-Phydroxylauroyl-CoA (2). It is racemized by a racemase
isolated from mitochondria to L-(+)-$-hydroxylauroyl-CoA
( 3 ) which is dehydrogenated by $-hydroxyacyl dehydrogenase
( H O A D H ) [specific for the form] t o $-ketolauroyl-CoA
( 4 ) and so removed from the equilibrium.
Angew. Chem. internot. Edit.
/
Vol. 3 (1964) 1 No. 5
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