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Cyclopentadienyl-(benzene)-molybdenum.

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(3) shown in Equation (a), together with only a small quantity of the 1,2-adduct (4) [3]. The product (3) has mainly
the trans-configuration (strong absorption at 950 to 960
+
H2C=CRI-CR2=CHR3 -+
(2)
R,Sn-CH2CRI=CRz-CH2R3
R3Sn-CHz-CHRlCR2=CHR3
(3)
(4)
(a) R3SnH
ill
+
cm-I). The trialkylstannyl group adds preferentially to
the unsubstituted end of the conjugated system (2). If, as
in Equation (b), a primary carbon atom can become a radical
center (R3 = H), this reacts preferentially with the H of a
further molecule of ( I ) ; about 80 of the 1,4-adduct ( 3 ) as
obtained. If only secondary carbon atoms are radical centers
or from sodium acetylides with carbon disulfide and sulfur
(e.g. in acetonitrile) at room temperature. Mercaptoethynyl
compounds [I], which are produced by the action of sulfur
on sodium acetylides, also add on carbon disulfide in polar
solvents at room temperature, and are cyclized by nucleophilic attack of the thiolic sulfur of the trithiocarbonate group
on the triple bond.
r
1
L
J
(I): R = C~HS
(2): R = H
:(,
(b) R ~ S ~ - C H Z - C R I - C R ~ = C H Rt-f
~ R3Sn-CH2-CRI=CR2-CHR3
(R3 = methyl), the yield of 1,2-adduct (4) rises to ca. 35 %.
With dimethylbutadiene (R1 = R2 = CH3), the tertiary carbon atom is apparently favored as a radical center [left-hand
limiting structure in (b)], leading to an increased proportion
of ( 4 ) . The same effect in the case of phenylbutadiene (R3=
C6Hs) probably causes its tendency to form the styrene system. Diisobutylstannane reacts analogously to ( I ) .
For analysis of the mixtures (3) i(4), among other methods,
titration with iodine at 0-20°C was used for the selective
estimation of ( 3 ) , for iodine splits off the allylic alkylstannyl
group rapidly and quantitatively. We have also prepared a
number of possible isomers by independent synthesis.
Table I. Hydrostannation of dienes according to Reaction (a)
at 70-75 "C. Catalyst: azoisobutyronitrile; excess of diene: 100 %.
1
Diene
H2C=CH-CH=CHz
H2C=CH-C(CH,)=CHz
HzC=(CH,)C-C(CHd=CH2
HzC=CH-CH=CH-CH,
(
HZC=(CH~)C-C(CH~)=CH~
1-51
(5)
H2C=CH-CH=CH-C6H5
Cyclopentadiene
Cyclopentadiene
Organotin
hydride
I
Adduct (Yield (3)
b'p'
[ "C/mm He1
120-122/44
103-106/12
109- 1 1 1 /12
100- 103/12
100- 101 /o. 1
m.p. 69 "C [b]
180--185/12
-
110-1 13/12
m. p. 84 "C [b]
+ ( 4 ) = 75-96
% 1,4(3)
1
%)
% 1,2-
(4)
80
81 [a]
68
66
72
20
19
32
34
28
395
70
64
87 [c]
<5
30
36
13
a94
<6
Average yields of 50-70 % are obtained. Thus, sodium
(1)
phenylacetylide affords 60 % phenyl-l,3-dithiole-2-thione
when the reaction is performed in acetonitrile. The parent
compound, viz. 1,3-dithiole-2-thione(2), is accessible in 25 %
yield from acetylene or sodium acetylide [2].
Received, December 2nd, 1963 [ Z 630/456 IE]
German version. Angew. Chem. 76, 143 (1964)
[ I ] L. Brandsmn, H. Wijers, and 3. F. h e n s , Recueil Trav. chim.
Pays-Bas 81, 583 (1962); M . Schmidt and V. Potschka, Naturwissenschaften 50, 302 (1963).
[2] Cf. R . Mayer and B. Gebhardf, Chem. Ber., in the press,
where an introduction, to the literature of isotrithiones is also
given.
Cyclopentadienyl-(benzene)-molybdenum
By Prof. Dr. E. 0. Fischer and Dip1.-Chem. F. J. Kohl
Institut fur Anorganische Chemie
der Universitat Munchen (Germany)
In the course of an investigation of the behavior of
[C5H5MC&(CO)]+
ions (M = Mo or W) [I] toward
nucleophilic reagents, we discovered a new type of synthesis
for C5H+fC,jH6 n-complexes. If red [ C ~ H ~ M O C ~ H ~ ( C O ) ] P F ~
is treated with hydride ions as nucleophilic reagent, the
carbonyl group is eliminated and cyclopentadienyl-(benzene)-molybdenum, m.p. 216-21 8 "C, is obtained according
to the equation :
[a] Contains very little OF the inverse 4,1-adduct,
[b] From ethanol.
[c] By-product: adduct formed with dimeric cyclopentadiene, b.p. 167"C/12 mm.
Received, November 26th, 1963 [ Z 623/453 IEI
German version: Angew. Chem. 76, 52 (1964)
[ I ] J . G . Nolres and G . J. M. van der Kerk, Chimia 16, 122 ( I 962),
where further references are given.
[la] W. P.Neumann, H . Niermann, and R . Sommer,Angew. Chem.
73, 768 (1961); Liebigs Ann. Chem. 659, 27 (1962).
[2] W . P. Neumann and R. Sommer, Liebigs Ann. Chem., in the
press.
[3] D.J. Cooke, G. Nickless, and F. H. Pollard (Chem. and Ind.
1963, 1493) expected to obtain only the 1,2-adduct on addition of
trimethylstannane onto piperylene, without considering the
possibility of 1,4-addition. They assumed that the geometric
isomerism of piperylene was the reason for the appearance of
several products.
The red compound is soluble in organic solvents, sublimes
in YOCLIO above 5OoC, and is extremely sensitive to air.
Evidence for its sandwich structure is provided by its infrared
spectrum. In agreement with earlier studies carried out on
CsHsCrC6H6 [2], typical absorptions are observed at 1404,
1096, 996, 814, and 791 cm-1 for the covalently bonded,
symmetrical C~H5-ligand (sym. C5v) in Nujol/Hostaflon.
Absorption bands at 1404, 977, 9 5 0 , 838, and 761 cm-J may
be assigned to the x-bonded undistorted benzene-ligand
(sym. C6V). The paramagnetism of the compound (1.68 B. M.)
[3] corresponds to the value for one unpaired electron. The
substance C ~ H ~ ( C ~ H ~ ) M
which
O H would be a feasible
intermediate between ( C ~ H & M O H[41
~ and (C6N6)ZMo [51 in
the isoelectronic series, was not observed.
Received, December 5tb, 1963
[ Z 627/457 IEI
German version: Angew. Chem. 76, 98 (1964)
Synthesis of 1,3-Dithiole-2-thiones("Isotrithiones")
By Prof. Dr. Roland Mayer, Dip1.-Chem. B. Gebhardt,
DipLChem. J. Fabian, and A. K. Muller
Institut fur Organische Chemie
der Technischen Universitat Dresden (Germany)
1,3-Dithiole-2-thiones(1,3-dithiacyclopentene-2-thiones)
arise
by the simultaneous action of carbon disulfide and sulfur on
acetylene in polar solvents at somewhat elevated temperatures
134
[I] E. 0. Fischer and F. J . Kohl, Z. Naturforsch. 186, 504 (1963).
[2] J . Manchot, Ph. D. Thesis, Technische Hochschule Miinchen,
1963; E. 0. Fischer and H. P. Kogler, Z. Naturforsch. 136, 197
(1958).
[3] Measurements carried out by K. Schwarzhans.
[4] M. L. H . Green, C . N. Street, and G . Wilkinson, Z. Naturforsch. 146, 738 (1959); E. 0. Fischer and Y . Hristidu, Z. Naturforsch. 156, 135 (1960).
[5] E. 0. Fischerand H . 0. Stah/, Chem. Ber. 89, 1805 (1956).
Angew. Chem. internat. Edit.
/
Vol. 3 (1964) 1 No. 2
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