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Dimerization of Thiophene to Give a Linear S(CH)8S Fragment with [(C5Me5)Rh(C2H4)2].

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[3] a ) U. F. Franck, Anxeir.. Chem. 1978, 90, 1; Angeir.. Chem. I n t . Ed. En&'/.
1978, 17. 1 ; b) R. J. Field in Oscillations and Travelling Wuves in Chemical
.?vxiems (Eds.: R. J. Field, M. Burger), Wiley, New York, 1985. Chapter 2.
[4] L. Gyorgi. T. Turanyi. R. J. Field, 1 Phvs. Chem. 1990, 94, 7162.
[5] A. D. Kardvaev, G. S. Pdrshin, 1
. P. Kazakov, I;ve.~t.Akad. Nark SSSR,
Sw. Khirn. 1980, 221.
[6] a) F. Bolletta. V. Balrani. 1 Am. Chem. Sor. 1982, 104, 4250; b) H. R.
Weigt. H. Ritschel. G . Junghdhnel. Z . Ch1.m. 1983. 23. 152; H. R. Weigt,
G . Junghihnel, ;bid. 1985, 25. 382; c) A. D. Karavaev, V. P. Kazakov.
G. A . Tolstikov, Teor. Eksp. Khirn. 1986, 65.
17) R. J. Watts. J. Chem. Educ. 1983, 60. 834.
[XI a) F. E. Lytle, D. M. Hercules, Pholorhem. Photohiol. 1971, 13, 123; b) I.
Rubinstein, A. J. Bard. J. Am. Chem. Sor. 1981, 103, 512.
[9] A. Pacault. P. Hanusse, P. De Kepper. C. Vidal, J. Boissonade, Arc. Chem.
Rrs. 1976. 9. 43s.
[lo] a) The chernilumi~~escence
was registered with a photomultiplier after including a high-intensity monochromator (Bausch & Lomb) in the circuit.
Measurements were performed a t an OCL wavelength maximum of
610 nm (spectral width: 10 nm). The OCL spectrum agrees both with the
stationary photoluminescence (see [6a,b] and H. R. Weigt. Dbserfufion.
Phdagogische Hochschule Potsdam, 1984) and the oscillating photoluminescence (H. R. Weigt, unpublished); b) the potential was recorded at a
platinum redox electrode (MC 20, Meinsberg) relative to a silver chloride
electrode (SE 20. Meinsberg).
[ I l l A. D. Karavaev. V. P. Kazakov, Teor. Eksp. Khim. 1990, 566.
112) P. Ruoff. R. M. Noyes, 1 Phps. Chem. 1989, 93, 7394.
1131 H . Saigusa, C k m . Phps. Lerf. 1989. 157, 251.
1141 Oxygen (technical quality) was introduced into the lower part of the redctor through a capillary. The gas flow was determined with a flow meler
(TG 400, Medingen).
Dimerization of Thiophene to Give a Linear
S(CH),S Fragment with [(C,Me,)Rh(C,H,),]
The 'H NMR spectrum shows eight distinct multiplets for
the eight methine groups; a COSY spectrum (COSY =
correlated spectroscopy) indicates that these groups are attached in a linear array. Two distinct C,Me, resonances are
also observed. The 13C NMR spectrum shows two downfield singlet and six upfield doublet resonances, suggesting
that six carbons in the chain are attached to metal centers. A
3C/1H HETCOR spectrum (HECTOR = heteronuclear
correlation) shows that these six carbons are adjacent to each
other at an end of the (CH), chain. These data led to the
formulation of 1 as indicated in Equation (b). Use of a-deu-
teriothiophene in the reaction leads to a product in which the
resonances at 6 = 6.503, 6.009,4.165, and 3.245 are diminished in intensity by half, indicating that the S(CH),S fragment arises by the coupling of two a thiophene carbons after
C-S cleavage.
Confirmation of the structure deduced from NMR results
was obtained from a single-crystal X-ray diffraction study."]
Since the compound proved difficult to crystallize, a preliminary data set was obtained on a small crystal (Fig. 1). A
By Robert M . Chin and Wiiiiam D . Jones*
Reactions of thiophenes with transition metals as models
for studying the hydrodesulfurization of petroleum have
aroused increased interest over the past few years."' A variety of coordination modes of thiophene have been found,[*]
and reactions in which the ring has been cleaved have been
The simple insertion of an unsaturated rhodiurnt4]or iridium"] metal center into the thiophene C-S bond
has also been examined [Eq. (a)], and we report here an
example in which C-C bond formation occurs concomitant
with the C-S cleavage.
Heating a solution of [(C,Me,)Rh(C,H,),] with a 20-fold
excess of thiophene in benzene solution at 90 "C for 15 h was
followed by removal of solvent and extraction of the residue
with hexane. Upon cooling a red-black precipitate forms.
The product is identified as 1 on the basis of NMR and
Fig. 1. PLUTO drawing of the structure of 1 in the solid state. Selected distances. Rh(1)-S(l), 2.38(2); Rh(1)-C(l), 2.1 1(7); Rh(l)-C(2). 2.15(7); Rh(1)C(3), 2.30(7); Rh(2)-S(2), 2.36(2); Rh(2)-C(4), 2.19(6); Rh(2)-C(5), 2.12(7);
Rh(2)-C(6), 2.31(7); %I)-C(l), 1.65(8); S(2)-C(S), 1.80(7); C(I)-C(2). lS(1);
C(2)-C(3), 1.54(9); C(3)-C(4), 1.5(1); C(4)-C(5), 1.33(8); C(5)-C(6), 1.4(1);
C(6)-C(7), 1.5(1); C(7)-C(8), 1.4(1)
[*] Prof. W D. Jones, R. M. Chin
Department of Chemistry University of Rochester, Rochester,
NY 14627 (USA)
[**I This work was supported by the National Science Foundation grant CHE9102318.
Angew C h w . h i . Ed. EngI. 31 (1992) No. 3
more symmetric molecule with the S(CH),S unit bound in a
1 ,2,3,4-q4-7,8,9,10-q4 fashion is not observed, despite the
fact that [ (C,Me,)Rh(polyolefin)] complexes are expected to
be labile at 200 T , [ ' l leading to the conclusion that the structure observed for 1 is thermodynamically preferred.
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Irradiation (310-380 nm, 25 "C) of a 0.034 M solution of
in [DJbenzene containing a ninefold
excess of thiophene shows the formation of both a small
amount of 1 and another material displaying four low-field
resonances in the 'H NMR spectrum. In addition to a
C,Me, resonance at 6 = 1.504, multiplets are seen at 6 =
11.843 (ddd, J = 9 . 2 , 6.3, 1 . 6 H ~ IH),
9,082 (dd, J = 8 . 7 ,
[ (C,Me,)Rh(C,H,),]
(ddd, J = 9.0, 7.1, 1.3 Hz, 1 H), suggesting the presence of
aldehydic and/or carbenoid hydrogens. This intermediate is
tentatively assigned structure 2 [Eq. (c)], and reacts thermal-
-2 C2Hq
ly to form dimer 1. A methyl-substituted iridium analogue
of 2 which also displays low field resonances for the metallacycle hydrogens, has been isolated as a stable species.[51Further mechanistic details are under investigation.
Received: October 7, 1991 [ Z 4960 IE]
German version: Angew. Chem. 1992, 104, 340
[I] R. J. Angelici, Acr. Chem. Res. 1988, 21, 387-394; C. M. Friend, J. T.
Roberts, ibid. 1988, 21, 394-400.
[2] R. J. Angelici, Coord. Chem. Rev. 1990,105,61-76; T. B. Rauchfuss, Prog.
Inorg. Chem. 1991, 39, 259-329.
[3] G. H. Spies, R. J. Angelici, Organometullics 1987, 6, 1897-1903; J. W.
Hachgenei, R. J. Angelici, J. Organomet. Chem. 1988,355,359-378; A. E.
Ogilvy, M. Draganjac, T. B. Rauchfuss, S . R. Wilson, OrganometaNics
1988, 7,1171 -1177; P. Hubener, E. Weiss, J. Organornet. Chem. 1977, 129,
[41 W. D. Jones, L. Dong, J. Am. ChemSoc. 1991,113,559-564; L. Dong, S. B.
Duckett, K. F. Ohman, W. D. Jones, ibid. 1992, 114, 151-160.
[S] J. Chen, L. M. Daniels, R. J. Angelici, ibid. 1990, 112, 119-204.
[6] ' H NMR (400 MHz, C,D,, 25°C): 6 = 6.503 (dd, J = 5.5, 3.3 Hz, Ha);
6.009 (dt. J = 3.9, 1.0 Hz, H I ) ; 5.492 (dd, J = 6.4, 3.9 Hz, H,); 4.900 (ddd,
J = 8.0. 3.9, 2.0 Hz, H2); 4.818 (dd, J = 6.8, 4.0 Hz, Hh); 4.165 (ddd,
7.9, 1.3 Hz, H3); 1.681 (s, C,Me,); 1.463 (s, C,Me,). 13C('H} NMR
(100MHz. C,D,. 25°C): 6 =140.14 (s, Ha); 121.55 (s, H,); 92.17 (d,
J = 9 . 5 H ~ , H , ) ; 8 7 . 4 6 ( d , J = 6 . 0 H z , H , ) ; 8 6 . 1 4 ( d , J =6.0Hz,H,);82.69
( d , J = 1 2 . 1 Hz,H6);76.26(d, J = ~ . O H Z . H , ) ; ~ ~ . ~ O ( ~ , J = ~ O . ~ H Z , H , ) ;
96.71 (d, J = 6.7 Hz, C,Me,); 96.82 (d, J = 5.7 Hz, C,Me,); 10.05 (s,
C,Me,) 9.08 (s, C,Me,). Correct C,H analyses for Rh,S,C2,H3,. Isolated
yield ca. 50%.
171 Complex 1 crystallizes in monoclinic space group P2Jc with a = 12.810(9),
b=16.118(17), c=14.025(25)A, ~=109.78(10)",and 2 = 4 . Ofthe4468
data collected on a 0.1 x 0.1 x 0.1 mm3 crystal, 791 with I z 3 4 0 were
used to solve the structure, in which a model was used with the C,Me,
ligands refined as rigid groups and only rhodium and sulfur refined anisotropically to give final agreement parameters of R = 0.105, R, = 0.113.
Further details of the crystal structure investigation are available on request
from the Director of the Cambridge Crystallographic Data Centre, University Chemical Laboratory, Lensfield Road, GB-Cambridge CB21EW(UK).
on quoting the full journal citation.
[8] A. K. Smith, P. M. Maitlis, J. Chem. SOL..,Dalton Trans. 1976, 1773- 1777.
Liquid Crystallinity in Polymers. Principles and Fundamental
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c2h4, c5me5, dimerization, thiophene, give, fragmenty, linear
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