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Control of the Reaction of n-Butyllithium with Benzo[b]tellurophene by the SolventЧEither Metalation or TelluriumЦLithium Exchange To Give an Interesting Lithiostyryllithium.

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yield > 90%) [I,][SbF,], in approximately 90 % yield
(residual nitrogen content ca. 0.4-0.5%; cf. 1, calcd. 7.9%)
[Eq.(ell.
21
--t
[I,][SbF6],
+ 3 N,
(e)
It would have been also conceivable that the reaction of
IN, with "I+" [Eq.(a)J could have resulted in a particle isomeric to the cation in 1. Since the strong asymmetric N,
vibration (vas = 2067 cm- ')['I in the Raman spectrum made
the linear arrangement of the two iodine atoms at the N, unit
seem
we calculated a structure with a bent I,
unit and another with C,, symmetry for the cation in 1 based
on ab initio MO calculations (Fig. 2). The calculations were
2.717
@?
A(E
=
B ( E = -185.95005)
-185.95201)
Fig. 2. MP2 optimized structures for the [J,N,]+ ion, basis sets see text; (bond
angles [-I. distances [A], energies [Hartree])[l7]: A : nonplanar, chainlike structure of the cation in I , B: energetically next most favorable C, structure.
carried out with the Gaussian 90 program using the
6-31 + G* standard basis set for nitrogen.['sa*b!For iodine
a quasi-relativistic pseudopotential[' 6 a ] and a [5s5pl d]/
(3s3pld)(DZ + P) basis set were used.['6b1 The geometries
were fully optimized in accord with the electron correlation
according to Mraller-Plesset 2nd order (MP(FU)). In agreement with the experimental spectroscopic results, the ab initio calculation also shows that the nonplanar chainlike structure of the [I,N,]+ ion proposed by us is favored by about
1 kcalmol-' to the (not observed) C,, structure.
In a detailed work we will report the ab initio calculations
of IN, and other energetically more unfavorable, terminal
coordinated and cyclic [I,N,]+ ions as well as about an improved preparative method for the preparation of IN, in
gram quantities.
E.xperimenta1 Procedure
A solution of[I,][SbF,] (0.50 g, 0.81 mmol) in SO, ( 5 mL) at - 70 "C was added
to a suspension of AgN, (0.12 g, 0.80 mmol) [freshly prepared, washed with
ethanol and ether, and dried in vacuo] in SO, ( 2 mL). After the mixture was
swirled for 3 hat - 50 C it was filtered by decantation the precipated AgI under
constant cooling [7,18]. Caution: The explosive nature increases greatly from
AgN, to IN, to I! Compound I often shows also below -20°C explosive
decomposition.
Received: May 9, 1992 [Z53321E]
German version: Angew. Chem. 1992, 104, 1391
CAS Registry numbers:
A,N,, 13863-88-2; [I,][SbF,],
[I,][SbF,], , 117041-30-2.
117818-72-1; [I,N,][SbF,],
143007-78-7;
[I] R. H. Davies, A. Finch, P. N. Gates, J. Chem. SOC.Chem. Commun. 1989,
1461.
[2] 1. Tornieporth-Oetting,T. Klapotke, A n g w . Chem. 1990,102,726; Angew.
Cheni. Int. Ed. Engl. 1990.. 29, 677.
[3] H. Hartl.. H. Birnighausen, J. Jander, Z. Anorg. A&. Chrm. 1968, 375,
225.
[4] K. Dehnicke, Angew. Chrm. 1976, 88. 612; Angew. Chem. Int. Ed. Engl.
1976. 15. 553.
Angnv. Cheni. Int. Ed. Engl. 1992. 31, No. 10
0 VCH Verlugsgesellschaft mbH,
[5] R. Minkwitz, Angew. Chem. 1990, 102, 185: Angew. Chem. I n / . Ed. EngI.
1990, 29, 181.
[6] N. Burford, J. Passmore, J. C. P. Sanders in From Arom.5 to Po/b~mrr.s(Eds.:
J. F. Liebman, A. Greenberg), VCH, Weinhelm, 1989, p. 53.
[7] Raman (1 in SO, solution; 647.09 nm, 20 mW, - 50 T):dv[cm- '1 (intensity) assignment cf. ref. [4]: 182 (lo), ~ ( l - I ) :295 (8). e,(SbF,-): 355 (6).
v(N-1); 540(3), v(N,): 638(5), S(N,); 675 (8). v,(SbF,,-): 1286(7), L,?(N,);
2067 (8), VJN,). A band (238 cm-' 161) assignable to the starting material
[I,][SbF,] could not be observed.
[8] I. C. Tornieporth-Oetting, T. M. Klapotke, unpublished.
[9] K . Nakamoto, Infrared and Raman Spertru of'lnorgunic and Coordinatiun
Compounds, 4. ed., Wiley, New York, 1986.
[lo] N. N. Greenwood, A. Earnshaw, Chemistry of !he Elemenrs, Pergamon.
1984.
(1 11 Estimated from AH; (N;,g) = + 105 kcal mo1-l [I21 and AH:(I', g) =
f25.56 kcalmol-' [13].
[12] K. Jones in Comprehensive Inorganic Chemistry, Val. 2, (Eds.: J. C. Bailar,
J. J. EmelCus, R. Nyholm, A. F. Trotman-Dickenson), Pergamon, Oxford,
1973, p. 276.
[I31 D. A. Johnson, Somc Thermodwamic Aspects of' Inorganic Chcmisrry,
Cambridge University Press, Cambridge, 1982. appendix.
[14] D. W. H. Rankin, J. Chem. Sac. Dalton Truns. 1972. 869.
[15] a) M. J. Frisch, M. Head-Gordon, G. W. Trucks. J. B. Forseman, H. B.
Schlegel. K. Raghavachari, M. Robb. J. S. Binkley, C. Gonzalez, D. 1.
Defrees, D. J. Fox, R. A. Whiteside, R. Seeger, C. F. Melius, J. Baker. R. L.
Martin, L. R. Kahn, J. J. P. Stewart. S. Topiol. . A . Pople: Gaussian 90,
Revision E Gaussian Inc., Pittsburgh, PA, 1990; b) W J. Hehre. L. Radom.
P. von R. Schleyer, J. A. Piople, Ah Initio Molecular Orbital Theory. Wiley.
New York. 1986.
[I61 a ) P. Schwertfeger, M. Dolg, W. H. E. Schwarz, G. A. Bowmaker, P. D. W.
Boyd, J. Chem. Phvs. 1989,91, 1762; b) M. Kaupp, P. von R. Schleyer, H.
Stoll, H. Preuss, J. Am. Chem. SOC.1991, 113, 607.
[17] Since it is internationally acceptable the following non-SI units were used:
18, =10-"m, 1 cal = 4.18 J: 1 Hartree = 27.2eV = 627.4 kcal mol-'.
[18] Attempts at recording of a 14N NMR spectrum of a SO, solution of
[I,N,][SbF,] were unsuccessful (cf. ref.121). Furthermore, we were also not
in the position to carry out a favorable synthesis for AgN,, starting from
commercial "NH,CI.
Control of the Reaction of n-Butyllithium
with Benzo[b]teUurophene by the SolventEither Metalation or Tellurium-Lithium Exchange
To Give an Interesting Lithiostyryllithium""
By Adalbert Maercker,* Heinrich Bodenstedt,
and Lambert Brandsma
Dedicated to Professor Ulrich Schollkopf
on the occasion of his 65th birthday
The reductive cleavage of diphenylmethylene cyclobutane
with elemental lithium leads to 2,5-dilithio-l,l-diphenyl-lpentene (l),which is rearranged by a 1,7 proton shift into the
stable dilithio compound 2a.L" According to 2D NMR investigations['] 2a has a lithium double bridge, similar to the
metalated addition product of n-butyllithium with diphenylacetylene (tolane) 2 b.[31
It was now of interest to prepare the parent compound of
both compounds 2 with R' = R2 = H, that is, (Z)-2-lithiostyryllithium (8). The readily accessible benzo[b]tellurophene
(4)["] was clearly a potential starting material that should be
[*] Prof. Dr. A. Maercker, 1ng.-grad. H. Bodenstedt
[nstitut fur Organische Chemie der Universitat
Adolf-Reichwein-Strasse, D-W-5900 Siegen (FRG)
[**I
Prof. Dr. L. Brandsma
Department of Preparative Organic Chemistry
University of Utrecbt. Padudlaan 8
NL-3584 CH Utrecht (The Netherlands)
Polylithiumorganic Compounds, Part 18. This work was supported by the
Fonds der Chemischen Industrie. Part 17: A. Maercker, K.-D. Klein,
J. Orgunomet. Chem. 1991, 410, C35-C38.
W-6940 Weinhelm. 1992
0570-0833/92/1010-1339 $3.50+.25/0
1339
C H
(CH2)3Li
C6H5
Li
5>c=c<
1
C H
/C6H5
C6H5
Li
9)c=c,
3
R:
2
a: R'
=
CH
,;,
b:
=
c,H,;
~1
/ R2
c=c
BuLi
3
stopped at the deep violet ate-complex 12 (Table 1). Stannates of the type 12 are discussedrs1as intermediates of the
tin-lithium exchange and have been detected already for
other special
In contrast, the conversion of 11 into 8 is achieved via the
diiodo compound 13 (Table l), which undergoes a double
iodine-lithium exchange. The Wittig reaction of bromo-
R2 = C3H,
~2 = C ~ H ~ Table 1. Important physical data for the compounds 8 and 11-13.
converted stereospecifically into 8 by tellurium-lithium exchange.
However, if benzo[b]tellurophene (4) is treated under the
usual conditions for tellurium-lithium exchanget5] with nBuLi in THF, then at - 78 "C no reaction occurs, whereas at
0 "C-as also previously in diethyl ether at room temperature[61--exclusively r-metalation was observed leading to 2lithiobenzo[b]tellurophene (5). The reaction of 5 with methyl
iodide afforded 616]in 88 % yield, and from deuterolysis 7 is
obtained with a degree of deuteration of > 98% in the n
position.
8: ' H N M R : see text; "CNMR (100.6MHq [D,,]Et,O): 6 =177.65 (m,
'J("C6Li) = 8.8,4.4 Hz, =CHLi), 173.1 (m, 'J(13C6Li) = 8.2,4.1 Hz, Ar-Li),
156.6, 156.2, 144.7, 128.8, 126.5, 124.0; 6LiNMR (58.9 MHz, [D,,]Et,O, standard 0.1 M LiBr in THF, external): 6 = 1.4, 0.9 (1 :1)
11: ' H N M R (200MH2, CDCI,):6 ~ 7 . 5 7(d, ' J = 1 0 . 5 Hz), 7.53 (d, 'J=
7.9Hz), 7.29-7.14 (m), 6.73 (d, ' J = l O . S Hz), 1.67-0.82 (m); "CNMR
(50.3 MHz; CDCl,):6 =150.0, 149.6, 139.7, 135.7, 133.1, 128.5, 127.1, 126.3.
29.2, 27.0, 13.6, 11.8; '"SnNMR (142 MHz, [D,,]Et,O, Standard 0 . 2 ~
(CH,),Sn in Et,O, external): 6 = - 6.4; MS (70 eV): m / z 335 ( M e , 0.2%), 279
(73), 223 (73), 221 (63), 120 (66), 41 (65). 29 (100); B.p. = 84-88 "C/0.002Torr;
correct element analysis
12: ' H N M R (400 MHz, [DL0]Et2O):6 = 6.75 (d, ' J = 6.9 Hz), 6.65 (t, 'J =
7 . 7 H ~ ) , 6 . 3 9 ( d 'J=7.7Hz),
,
5.87(t, ' J = 6 . 9 H z , 5.20(d,'J=10.6Hz),3.45
(d, ' J = 10.6 Hz), 1.54 (m), 1.36 (m), 1.12 (t. ' J = 8.4 Hz), 0.87 (t, 'J = 7.3 Hz);
'3CNMR(100.6MHz,[Dlo]Et,0):6
=152.6, 138.1,129.5,127.7, 113.9,112.0,
97.5, 30.6, 28.5, 14.4, 10.3; "'SnNMR (142 MHz, [D,,]Et,O, standard 0.2 M
(CH,),Sn in Et,O, external): 6 = - 44.0
13: ' H N M R (200 MHz, CDCI,): d =7.86 (d, 'J=7.9Hz), 7.53 (d, 'J=
7.6Hz),7.37(t, ' J = 7 . 6 H ~ ) , 7 . 2 1 (d, ' J = 8 . 4 H z ) , 7.02(t, 'J=7.9Hz),6.70
(d,'J=8.4H~);''CNMR(50.3MHz,CDCI,):6=143.1,141.3,139.1,129.8,
129.7,127.9,99.0,84.2; MS (70 eV): mlz 356(Me, 4%), 229 (96), 102 (loo), 76
(20), 75 (24). 74 (16), 50 (20); h.p.
elemental analysis
=
65-75 T / O . O O l Torr (decomp.); correct
7
BuLi
BupTe
1
hexane
20°C
H\
8
\ BuLi
9
/D
methylenetriphenylphosphorane['O1 with o-bromobenzaldehyde in contrast affords a cis-trans mixture of the corresponding dibromo compound, which in contrast to 13 does
not lead to a sterically uniform product after halogen-metal
exchange.
BuLi
12
10
l1
- Bu2snIz
I
hexane
- BUI
8
13
BuLi
11
12
Surprisingly, the reaction of n-BuLi with 4 in hexane as
solvent occurred very differently. If the components are
stirred under an inert atmosphere at room temperature,
within 5-10 min a fine, light-brown precipitate is formed,
which proved to be the pure dilithium compound 8 (94%
yield). The powder, which is beige when dry, is highly
pyrophoric and dissolves in diethyl ether to give a red-brown
solution. Following hydrolysis the mother liquor, apart from
the theoretically expected quantities of dibutyltellurium,
contains only traces of styrene.
The reaction of a suspension of 8 in hexane with methyl
iodide or-better4imethylsulfate affords pure 9,17]which
is identical with the cis part of a cis-trans mixture prepared
as a reference. Interestingly, 1,l -di-n-butylbenzo[b]stannophene (11) (82% yield, Table 1) formed from 8 and di-nbutyldichlorostannane could not be converted back into 8 by
tin-lithium exchange. On the contrary the reaction in hexane
1340
0 VCH Verlagsgeseilschajt mbH, W-6940 Weinheim. 1992
For the preparation of 8 there are therefore no suitable
alternatives to the tellurium-lithium exchange 4 + 8. It is
noteworthy that this reaction was successful in a hydrocarbon solvent; furthermore, 8 is the first dilithium organic
compound with two different anionic centers, which was
made accessible by a tellurium-lithium exchange.
The structure and stereochemistry of the lithiostyryllithium (8) are also derived from the NMR spectra.["] Particularly characteristic in the 'H NMR spectrum (80 MHz,
[D,,]diethyl ether) is the doublet of the vinyl proton in the p
position to the lithium atom at 6 = 8.50 ( 3 J = 17.0 Hz),
which, as expected, yields a singlet" in the a-deuterated
compound 10, and the doublet of the aryl proton in the ortho
position to the lithium atom at 6 = 7.96 ( 3 J = 6.7 Hz). The
doublet of the vinyl proton in the a position (6 = 7.17) relative to the lithium atom lies partially beneath the signals of
the remaining arene protons (6 = 6.8-7.1), so only the peak
at lower field (6 = 7.25) can be seen. Obviously no signal is
detected for 10 in this region. The I3C and 6Li NMR spectra
(Table 1) are in agreement with a dimeric structure for 8, as
this has already been observed for compounds 2[23'1 under
certain conditions. The result["] is however novel and unex-
OS70-0833/92JlOlO-1340R 3.50+.25/0
Angew. Chem. I n f . Ed. Engl. 1992, 31, N o . 10
pected in that this information can already be taken from the
spectra recorded at room temperature, whereas cooling to
- 70 "C was necessary for the resolution of the 13C,6Li coupling in 2.
Experimental Procedure
A solution of 1 . 6 ~nBuLi (50 mL, 80 mmol) in hexane (Metallgesellschaft,
Frankfurt am Main) was added under argon at room temperature to 4 (6.9 g,
30mmol)[4]. This formed a pale yellow, clear solution which after 5-10 min
clouded and became light brown as a result of precipitated 8. After the mixture
was stirred for 3 h (magnetic stirrer), the precipitate was separated by decantation, washed three times with dry pentane (50 mL), and dried in vacuo. Yield:
3.3 g (94%) 8 as a fine, beige powder which ignites immediately on contact with
air.
Received: May 21, 1992 [Z5341IE]
German version: Angew. Chem. 1992, 104, 1387
CAS Registry numbers:
4,272-35-5; 6,50519-02-3; 7,143077-01-4;8,143077-02-5;10,143077-03-6; 11,
143077-04-7; 12, 143077-06-9; 13, 143077-05-8; BuLi, 109-72-8.
A. Maercker. K.-D. Klein, J. Organomet. Chem. 1991, 401, ClGC4.
a) 0. Eppers, H. Gunther, K.-D. Klein, A. Maercker, Mugn. Res. Chem.
1991.29,1065-1067; b) H. Giinther, 0. Eppers, K.-D. Klein, A. Maercker, unpublished.
W. Bauer, M. Feigel, G. Miiller, P. von R. Schleyer, J. Am. Chem. Soc.
1988. 110. 6033-6046.
L. Brdndsma, H. Hommes, H. D. Verkruijsse, R. L. P. de Jong. Reel. Truv.
Chim. Pays-Bus 1985,104,226-230.
a) D. Hellwinkel, G. Fahrbach, Chem. Ber. 1968, 101, 574-584; b) D.
Seebach, A. K. Beck, ihid. 1975, 108,314-321; c) E. Luppold, E. Miiller,
W. Winter, Z . Nuturforsch. B. 1976, 31. 1654-1657; d) M. J. M. Schoufs,
Dissertation, Universitat Utrecht, 1978; e) T. Kauffmann, H. Ahlers,
Chem. Ber. 1983,1~6,1001-1008;Review: T. Kauffmann, Angew. Chem.
1982, 94, 401 -420; Angew. Cheni. Int. Ed. Engl. 1982,21,410-429; f) T.
Hiiro. N. Kambe, A. Ogawa, N. Miyoshi, S. Murai, N. Sonoda, ihid. 1987,
99,1221-1222and1987,26,1187-118E;g)S. M.Barros,J. V.Comasseto,
J. Berriel, Tetrahedron Lett. 1989, 30, 7353-7356; h) Review: N. Petrag
nani, J. V. Comasseto, Synthesis 1991, 793-817, 897-919.
J.-L. Piette, J.-M. Talbot, J:C. Genard, M. Renson, Bull. Sot. Chim. Fr.
1973, 2468-2471.
R . Wehrli. H. Heimgartner, H. Schmid, H.-J. Hansen, Helv. Chim. Acta
1977, 60, 2053.
H. J. Reich, N. H. Phillips. J. Am. Chem. Soc. 1986,108,2102-2103; Pure
Appl. Chem. 1987, 59, 1021 -1026.
A. J. Ashe 111. L. L. Lohr, S. M. Al-Tawee, Orgunometallics 1991, 10,
2424.~2431.
G. Kobrich, H. Trapp, K. Flory, W. Drischel, Chem. Ber. 1966, 99, 689697.
Thorough 2D NMR investigations are in progress: H. Giinther, H.-E.
Mons. H. Bodenstedt, A. Maercker, L. Brandsma, unpublished.
Theoretically this is a 1 :1 : 1 triplet with 'J('H, 'H) = 2.6 Hz, however it is
not resolved.
a metal-atom vapor synthesis employing cobalt and pentamethylcyclopentadiene."] This unusual compound features
a formal Co-Co double bond without any bridging ligands.['] Some of the physical properties and the reactivity
of 1 were surprising to us in light of the proposed structure.
Despite its even valence electron count (28 valence electrons
per dimer, Co', ds), 1 was reported to be paramagnetic. It
apparently did not react with ethylene or carbon monoxide.
Finally, the X-ray crystal structure featured considerable
residual electron density (2.5 e k 3 ) in a position bridging
the two metal atoms. Sensitized to the difficulty of characterizing paramagnetic hydrides by our recent work on
[{Cp*Cr(p3-H)),],IL1we wondered whether 1 might not contain bridging hydride l i g a n d ~ ,and
~ ~ ]if this compound could
be prepared by straightforward solution chemistry. Herein
we report the combined results of independent experiments
in this regard by two laboratories (in Delaware and Wisconsin), which led us to conclude that 1 is really the mixed-valent
cobalt hydride [C~~CO,(~,-H),].["~
In work carried out at the University of Delaware, reaction of [ ( C ~ * C O ( ~ - C ~ with
) ) , ] 0.5
~ ~ equivalents
~
of LiAIH, at
ambient temperature in THF gave a dark red solution. Subsequent removal of THF, extraction with pentane, filtration,
and evaporation of the solvent yielded the crude reaction
product as a black solid. 'H NMR analysis of this solid in
[D,]benzene revealed two major broad resonances at
6 = 62.0 and 29.6 of roughly equal intensity, besides minor
diamagnetic contaminants. Vacuum sublimation at 50 "C afforded a purple solid, which could be further purified by
recrystallization from pentane. The resulting material (2)
exhibited one resonance in the ' H N M R spectrum
([D,]benzene) at 6 = 29.6. The sublimation residue was recrystallized from pentane to yield black crystals; the
'H NMR spectrum ([D,]benzene) of the latter consisted of a
single broad resonance at 6 = 62.0, very close to the value
reported for 1. As the original report gave NMR shifts in
[DJtoluene (6 = 61.3 at 30 oC),[ll we recorded spectra in the
same solvent (6 = 63.0 at 20 "C and 60.3 at 30 "C). Given the
apparent temperature dependence of the chemical shift, we
considered all of these values to be identical within experimental uncertainty.
Presuming to have prepared 1 by an alternate route, we
determined the crystal structure of our black compound ex-
"[Cp*Co=CoCp*]" is a Hydride**
By Jorg L. Kersten, Arnold L. Rheingold,
Klaus H . Theopold,* Charles P . Casey, Ross A . Widenhoefer,
and Cornelis E. C. A . Hop
Recently, bis(~5-pentamethylcyclopentadienyl)dicobalt
([Cp*Co=CoCp*], 1) was reported to have been prepared by
[*] Prof. K. H. Theopold, J. L. Kersten, Prof. A. L. Rheingold
[**I
Department of Chemistry and Biochemistry
University of Delaware
Newark, DE 19716 (USA)
Prof. C. P. Casey, R. A. Widenhoefer, Dr. C. E. C. A. Hop
Department of Chemistry
University of Wisconsin
Madison WI 53706 (USA)
This work was supported by grants from the Petroleum Research Fund of
the American Chemical Society and the U.S. National Science Foundation
(KHT) and by the U.S. Department of Energy, Division of Basic Energy
Sciences (CPC). Cp* = C,Me,.
Angew. Chem. Int. Ed. Engl. 1992, 31, No. 10
0 VCH
U
Fig. 1. The molecular structure of [Cp:Co,(pc,-H),(p,-H)l (3). The hydride
ligands were not located and thus are not shown. Selected bond distances [A]
and angles ["I: Co(1)-Co(2) 2.479(4); Co(l)-Co(3) 2.472(4); Co(2)-co(3)
2.477(4); Co-C 2.109 (average); Co(2)-Co(l)-Co(3) 60.0(1); Co(l)-Co(2)-Co(3)
59.8(1); Co(l)-C0(3)-Co(2) 60.1(1). The Cp* centroids are displaced below the
Co, plane by an average distance of 0.193 A.
Yerlagsgeseilschaft mhH. W-6940 Weinheim, 1992
0S70-0833/92/1Ol0-1341S 3.S0+.2S/0
1341
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