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the phosphane apparently determines the course of reaco,p'-Dibenzene**
tion in this case. In agreement with this hypothesis, nBu,P
By Ralf Braun, Matthias Kummer, Hans-Dieter Martin, *
reacts with CS2 to give only the zwitterion H B U ~ ~ - ~ S ~ . [ ~ ]
and Mordecai B. Rubin*
An X-ray structure analysis of the corresponding triethyl
The family of (CH),, hydrocarbons includes a number
derivative is available."']
of
formal dimers of benzene, among which are the [2 21
1 represents a new type of phosphorus ylide which is
dimers 1 and 2, the [4+4] compound 3, ansaradiene (4),
readily accessible in high yields. The arrangement of the
and the [4+ 21 dimer tricycl0[6.2.2.0'~~]dodeca-3,5,9,11-teSe atoms in the five-membered ring is similar to that in
traene ("0.p'-dibenzene") 5 . While these dimers have been
tetraselenabisfulvalene derivatives, in which the intermoleof theoretical interest"], the only compounds described in
cular interactions between the heteroatoms are decisive for
the literature to date are 2['"] and 4.(2h1
An organometallic
the (super)conductivity. In dibenzotetraselenafulyalenes,
complex of 5 has been reported;131however, attempted libintermolecular Se. . . Se separations of 4.03 to 4.09 A["' are
eration of 5 from the complex resulted in isolation of benfound; in (TMTSF),AsF, (TMTSF = tetramethyltetraselenzene and not of its dimer. This result was attributed to the
afulvalene), 3.87 to 4.98 All4] (van der Waals radii for Se:
anticipated low thermal stability of 5 , which can revert to
2.01''I or 1.9 All6]). The shortest interomolecularSe . . .Se dismonomer by a thermally allowed, retro-Diels-Alder reactances in 1 are 3.49(1) and 3.91(1) A (Sel and Se4, respection.
We report here on the successful preparation of 5 by
tively). The specific conductivities measured with direct
low-temperature photolysis and the study of its thermal
and alternating current on pellets, are small
and
decomposition to benzene.
lo-' S/cm, respectively, at room temperature), which may
be due to the non-coplanar packing of the ring systems.
However, derivatives of 1 might have the properties of
"organic metals."
+
Received: August 5 , 1985 [Z 1413 IE]
German version: Angew. Chem. 97 (1985) 1057
[ I ] R. L. Greene, G. B. Street, Science 226 (1984) 651.
121 G. Wegner, Contemp. Top. Polym. Sci. 5 (1984) 281; Angew. Chem. 93
(1981) 352; Angew. Chem. Int. Ed. Engl. 20 (1981) 361.
[3] R. H. Baughman, Contemp. Top. Polym. Sci. 8 (1984) 321.
[4] J. 0. Besenhard, H. P. Fritz, Angew. Chem. 98 (1983) 954; Angew. Chem.
Inr. Ed. Engl. 22 (1983) 950.
(51 Y. Okamoto, P. S. Wojciechowski, J. Chem. Soc. Chem. Commun. 1983,
386.
[6] A. Kobayashi, N. Sasagawa, Y. Sasaki, K. Asakura, T. Yokoyama, H.
Ishii, N. Kosugi, J. Uuroda, H. Kobayashi, Chem. Lett. 1985. 1.
(71 H. P. Fritz, M. Weis, unpublished.
[8] K. A. Jensen, P. H. Nielsen, Acta Chem. Scand. 17 (1963) 549.
[9] Experimental procedure: All operations were carried out under Nz.
nBulP (3.9 mL, 15.77 mmol) in 30 mL of ether was added to a stirred
solution of CSe, (1 mL, 15.77 mmol) in 30 mL of ether with isopropanol/COI cooling. The reaction mixture was then heated to reflux with
addition of ether. Polymeric material was filtered off, the ether was removed from the filtrate, and the residue was recrystallized from ether.
Dark red, flat prisms (1.62g, 80%) were obtained which decompose at
93.5"C. Correct elemental analysis (C, H, P). IR (KBr): v=2950 (m),
2920 (m). 2860 (m), 1465 (m), 1385 (s), 1092 (m), 968 (s), 902 (vs), 750
(m), 510 (w), 378 (w) c m - ' ; ' H - N M R ( 6 0 MHz, C,,D,): 0.5<6<2.5 (m,
27H): "P-NMR (36.43 MHz, C,D,): 6=20.78 (s, I P); MS: m / z 554
(0.20%,M a ) , 478 (0.20), 396 (0.12), 282 ( I 1.98), 226 (21.73), 172 (IOO), 92
(24.14). 80 (56.52).
[lo] Crystal structure data: CI,H2,PSe4, ?=554.20: monoclinic, C2/c:
a=39.17(1), b = 13.414(3), c = 15.842(4) A, p=95.78(2)", V=8281.5 A':
psdlrrl=
1.778 g/cm' for Z = 16: p(MoKn)=70.85 cm-', F(000)=4288.
T= -35°C. 5713 measured, independent reflections, of which 2688 are
observed with I > 3 . 0 ~ ( 1 ) ,empirical absorption correction (o-scan,
Am= I " , ((sin8)/A),.,=0.55,
+ h , +k, ? I , MoKn,A=0.71069 A,graphite monochromator, Syntex P2,). Solution by direct methods, R =0.048,
R,=0.043, H'= I / [ a 2 ( F ~ ) + 0 . 0 0 0 0 6 F(anisotropic,
~]
H constant, 361 parameters. full matrix, SHELX 76). &(final)= +0.86/-0.63 e/A'. Further details of the crystal structure investigation are available on request
from the Fachinformationszentrum Energie, Physik, Mathematik
GmbH, D-75 14 Eggenstein-Leopoldshafen 2, by quoting the depository
number CSD 51552, the names of the authors, and the journal citation.
[ I l l Cf. d(C-Se) 1.692(2) A in CSe2 (A. G. Maki, R. L. Sams, J . Mol. Spectrosr. 9 0 ( 1981) 215) and 1.98(1) .& in Se(CH& (E. Goldish, K. Hedberg,
R. E. Marsh, V. Schomaker, J. Am. Chem. Soc. 77(1955) 2948).
"21 T. N. Margulis, D. H. J. Templeton, J. Am. Chem. Soc. 83 (1961) 995.
[I31 K. Lerstrup, M. Lee, F. M. Wiygul, T. J. Kistenmacher, D. 0. Cowan, J.
Chem. Soc. Chem. Commun. 1983, 294.
[I41 F. Wudl, J. A m . Chem. Soc. 103 (1981) 7064.
(151 L. Pauling: 7he Nature ofthe Chemical Bond, Cornell University Press,
Ithaca, NY, USA 1960.
I161 A. Bondi. J. Ph-vs. Chem. 68 (1964) 441.
Angew. C h m . Int. Ed. Engl. 24 (1985) N o . I.?
The unsaturated diketone 6 , prepared in yields of 10%
by [4 2]-cycloaddition of barrelene to o-benzoquinone in
anhydrous tetrahydrofuran (THF) at room t e m p e r a t ~ r e ~ ~ ]
[UV (methylcyclohexane): A,,,=456 nm ( E = 145); IR (methylcyclohexane: CH2Cl2 1 : 1) v,,,= 1740 cm-'; m.p.
126-129°C (dec.); ' H N M R (60 MHz, CDCI,): 6=2.45 (s,
2H), 3.43 (t, 2H), 3.61 (m, 2H), 5.93 (t, 2H), 6.14 (t, 2H),
+
8
9
[*] Prof. Dr. H:D. Martin, Dipl.-Chem. R. Braun,
DipLChem. M. Kummer
lnstitut fur Organische Chemie I der Universitat
Universitatsstrasse 1, D-4000 Diisseldorf (FRG)
Prof. M. B. Rubin
Department of Chemistry
Technion-Israel Institute of Technology
Haifa (Israel)
[**I Small and Medium rings, Part 55. This research was supported by the
Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie
and the BASF AG and, in part, by the Technion Fund for the Promotion
of Research. M. K. gratefully acknowledges a stipend from the Minerva
Foundation.-Part 54: K. Beck, S. Hunig, G. Kleefeld, H.-D. Martin, K.
Peters, F. Prokschy, H. G. v. Schnering, Chem. Ber., in press.
0 VCH Verlagsgesellschafr mbH, 0-6940 Weinheim. 1988
0870-0833/85/1212-l089 $ 02.80/0
1059
6.57 (t, 2 H)], underwent the e x p e ~ t e d ~photoisomeriza~.~]
tion to cyclobutanedione 7 [UV (methylcyclohexane):
/2,,,=496 nm (110); IR (methylcyclohexane :CH2C12 1 : 1)
v,,, = 1770, 1795 cm-'1 upon irradiation at 404 or 436 nm,
with isosbestic behavior in the early stages of the reaction
(305, 374 and 482 nm).
Irradiation of 7 in methylcyclohexane at room temperature (A= 496 nm) resulted in its conversion into benzene,
presumably via the intermediacy of 5 . The quantum efficiency for this reaction is greater than the maximum value
observed for formation of 7 from 6 . When the irradiation
was performed at -8O"C, the spectrum of a new compound was obtained with maxima in the ultraviolet at 294,
282, 271 and 260 nm (sh). The extinction coefficients were
of the order of 3000. The new compound is stable indefinitely at -80°C (cf. Fig. 1).
and naphthalene 8171 or anthracene 9Ia1is instructive. The
entropies of activation (25 "C) for 8 and 9 are - 5 and - 3
cal mol - I K - ' , respectively but the activation energies
(19.5 kcal mol-' for 8 and 24.9 kcal mol-' for 9 ) differ
markedly, reflecting the difference between formation of
two molecules of benzene from 5 vis-a-vis one of benzene
and one of naphthalene from 8 or one of benzene and one
of anthracene from 9 . We also note that the reported['"]
half-life of 2 at 40°C is 5.75 h, while tl,* for 5 is of the
order of 5 ms at this temperature. Irradiation of 5 through
quartz at -80°C resulted in almost quantitative conversion ( > 95% by UV spectroscopy) into benzene. In addition, poorly defined bands of low intensity were observed
at 355, 379, and 390 nm. Thus, the excited state of 5, which
has, a priori, many reaction paths available to it, proceeds
to the same product as the thermal reaction (possibly in a
stepwise fashion).
Received: July 30, 1985:
revised: September 23, 1985 [Z 1407 IE]
German version: Angew. Chem. 97 (1985) 1054
16-
CAS-Registry-numbers :
5,7322-47-6: 6,99096-99-8; 7,99097-00-4; benzene, 71-43-2; barrelene, 50024-3; o-benzoquinone, 583-63-1.
11L.
A
.
12.
111 D. Bryce-Smith, Chem. Commun. 1969, 806; R. Engelke, P. J. Hay, D. A.
10-
08.
06.
OL.
Oil
04
232
. 248. . Z .~ L. 280. . 296. . 312. . 328. . 3 .u
h[nrnl
-
Fig. I . UV spectroscopic monitoring of the generation of 5 from 7 at - 80°C.
Spectra after 10 0,30 0,
and 60 min @ irradiation at I > 380 nm. 0:
Spectrum after warming to -50°C (complete decomposition of 5 to benzene).
The above absorptions are assigned to o,p'-dibenzene
( 5 ) , on the following grounds: On the one hand, the spec-
trum is almost identical to that of the benzene-naphthalene
a d d ~ c t , " ~and,
~ ] o n the other, benzene is formed rapidly
and quantitatively upon warming. The kinetics of this retro-Diels-Alder reaction were measured by following the
disappearance of the maxima mentioned above at five
temperatures in the range -68 to - 52°C. Good first-order
behavior was observed in all cases and identical rate constants were obtained from measurements at different wavelengths at a given temperature. The results obtained fit the
Arrhenius expression:
Igk [s-'1
= (11.78k0.5)
-
(14.7k0.4)
2.303 RT
[kcal mol - '1
with AH' = 14.3 kcal mol-', AS'=
-6 cal mol-' K-I,
AG+ = 15.6 kcal mol-' (errors are double standard deviations). The minimal entropy change observed is consistent
with a rigid transition state for this highly exothermic reaction. Comparison of the activation parameters for the thermolysis of 5 with those reported for the thermal decomposition of the formal [4+2] addition products of benzene
1060
0 VCH Verlagsgesellschafi mbH, 0-6940 Weinheim, 1985
Kleier, W. E. Wadt, J . Am. Chem. SOC.106 (1984) 5439.
[2] a) H. Rottele, W. Martin, J. 0th. G. Schroder, Chem. Ber. 102 (1969)
3985; J. A. Berson, R. F. Davis, J. Am. Chem. SOC.94 (1972) 3658; b) H.
D. Martin, P. Pfohler, Angew. Chem. 90 (1978) 901; Angew. Chem. Int.
Ed. Engl. 17 (1978) 847.
[3] W. Grimme, E. Schneider, Angew. Chem. 89 (1977) 754: Angew. Chem.
Int. Ed. Engl. 16 (1977) 717.
[4] R. Braun, Diplomarbeit. Universitat Diisseldorf 1982. R. Braun, H. D.
Martin, in preparation.
[5] M. B. Rubin, M. Weiner, H. D. Scharf, J. Am. Chem. SOC.98 (1976) 5699;
M. B. Rubin, Topics Curr. Chem. 129 (1985) I .
[6] Quantum yields for this reaction exhibited wavelength, concentration,
temperature, and solvent dependence (cf. M. B. Rubin in Xth IUPAC
Symposium on Photochemistry (Interlaken, July, 1984). Presses Polytechniques Romandes, Lausanne 1984, p. 173. Optimal yields of 7 were obtained by irradiation of ca. 0.001 M solutions in methylcyclohexane at
50°C and 436 nm.
[7] W. Grimme, H. G. Koser, Angew. Chem. 92 (1980) 307; Angew. Chem. Inr.
Ed. Engl. 19 (1980) 307.
[8] N. C. Yang, M. J. Chen, P. Chen, J . Am. Chem. SOC. 106 (1984) 7310.
I(q5-C5Me5)~FezS41
and I(r15-C5Me5)zCozS41,
Two Novel Bis(pentamethylcyclopentadienylmeta1)
Complexes Rich in Sulfur
By Henri Brunner, Norbert Janietz, Waiter Meier,
Gertrud Sergeson, Joachim Wachter,* Thomas Zahn, and
Manfred L. Ziegler
The electronic and structural properties of [Cp,M,S,]
complexes (Cp: C5H5, MeC5H4 or C,Me,) depend, like
their reactivity, upon the transition metal M. Each of the
elements V,"] Cr, Mo, W,['I and FeL3]can be assigned to a
particular structural type. So far, nothing has been reported about a corresponding C o compound.
The complex [C5Me5(CO)Co)12, containing a Co=Co
bond, reacts with sulfur in toluene at room temperature
with formation of the green complex 1 in 23-39% yield.l4]
[C5Mes(CO)Co12+ 112 S8
* [(CSMe5)2C02S4] 1
I*] Dr. J. Wachter, Prof. Dr. H. Brunner, N. Janietz, W. Meier
lnstitut fur Anorganische Chemie der Universitat
Universitatsstrasse 3 I, D-8400 Regensburg (FRG)
G. Sergeson, Dipl.-Chem. T. Zahn, Prof. Dr. M. L. Ziegler
Anorganisch-chemisches lnstitut der Universitat
Im Neuenheimer Feld 270, D-6900 Heidelberg (FRG)
0570-0833/85/1212-1060 $ 02.50/0
Angew. Chem. In[. Ed. Engl. 24 (1985) No. 12
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