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Benzo-1 2 3-triselenolium Trifluoro-methanesulfonateЧa C2Se3 Radical Cationic Salt with Unusual Solid-State Structure.

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Compound 3 can be compared with its carbocyclic analogue 4[l61 only in solution, since 4 was not structurally
characterized. The z o 7 P b 1 Hand 2 0 7 P b 1 3 Ccoupling con= 33.6, lJpb,cz
= 5.8, 1Jpb,c3
= 31.8 Hz)
stants of 3 (*Jpb,"
are smaller than those of 4, which might indicate a larger
percentage of ionic bonding in 3. The significant deshielding
of the carbon atoms contained in the ring in 3 (6
C2,CS =161.71, C3,C4 =105.19) in comparison with the
pyrrole 2 (6 C 2,C 5 = 139.51, C 3,C 4 = 102.70) is contrary to
the coordination shift in the azacyclopentadienyl compounds of the transition metals.['* 7 , "I The exchange of two
4,R = tert-butyl
CH fragments contained in the ring of 4 for nitrogen atoms
leads to a significant deshielding of the Pb atom [S(207Pb)=
- 4142 in 3 in contrast to -4756 in 41. The mass spectrum
(EI) shows, probably as a result of the low thermal capacity
of 3 (decomposition above 104 "C), the molecular peak only
in low intensity.
The synthesis of the diazoplumbocene 3 shows that the
azacyclopentadienyl ligand is also suitable for the formation
of low molecular weight main group element 7c complexes.
This opens up new possibilities in the coordination chemistry
of pyrrole and its derivatives.
Experimental Procedure
To a suspension of PbCI, (1.39 g, 5.2 mmol) and 2,5-C,R2H,NLi (R = ierlbutyl) (1.94 g, 10.5 mmol) in toluene (50 mL), T HF (2 mL) was added, and the
mixture was stirred for 2 h. After the removal of the volatiles the residue was
extracted with n-pentane (40 mL). After recrystallization yellow crystals of 3
were obtained. Yield 2.50 g, (85%). M.p. 104°C (decomp).
' H N M R (60 MHz. C,F,, TMS int.): 6 = 5.51 (4H; C(3,4)-H; ' 1 ('07Pb,
'H) = 33.6 Hz). 1.39 (s, 36H; Me); I3CNMR (75.43 MHz, C,H,, TMS int.):
6 = 161.71 (C2.CS; 'J(Z07Pb,I3C) = 5.8 Hz), 105.19(C3,C4; 1J(207Pb,
"C) =
31.4 Hz). 33.31 (qC). 32.69 (Me); '"PbNMR (62.7 MHz, C,H,, PbMe, ext.):
6 = - 4142. - MS (70 eV, EI): m / z 564 (M', 1%), 386 ( M + - pyr, 20), 164
(pyr - H' - Me, IOO), and further fragments.
Received: December 19, 1991 [25081 IE]
German version: Angew. Chem. 1992, 104,766
[7] a ) N . Kuhn, K. Jendral, R. Boese, D. Bliser. Chem. Ber. 1991, 124, 89;
b) N. Kuhn, M. Kockerling, S. Stubenrauch, D. Blaser, R. Boese, J. Chem.
Soc. Chem. Commun. 1991, 1368.
[8] A bridging coordination of the azacyclopentadienyl ligand is observed in
several alkali metal complexes with the additional use of the lone pair on
the nitrogen atom: N. Kuhn. G. Henkel, J. Kreutzberg, Angew. Chem.
1990.102, 1179; Angew. Chem. Int. Ed. Engl. 1990,29,1143; K. Gregory,
M. Bremer, P. von R. Schleyer, P. A. A. Klusener, L. Brandsmd, i b d
1989, 101, 1261 bzw. 1989,28, 1224.
[lo] The plumbocene monomeric in the gas phase IS converted to a coordination polymer by the transition in the solid state; C . Panattoni, G. Bombierie, U. Croatto, A r m CrysraNogr. 1966, 2 / , 823; A. Almenningen, A.
Haaland, T. Motzfeld, J. Orgunomet. Chem. 1967, 7, 97.
[ l l ] 3: (133K): trigonaLP3, u=12.748(6), c=12.748(6).&, V = 3764.28A3,
Z = 6, pEalcd
=1.492 gcm-3, Mo,. radiation, 28,., = 48'. 4510 independent reflections, 4126 observed reflections (Fn> 3.920(F0)). R = 0.0343.
Rw = 0.0342, w = [a2(Fo)+ (0.01Fn)2]-l . There are two symmetry independent molecules in the crystal with only a few differences in the molecular geometry; for the discussion the data of the Pb 1 containing molecule
were used. Further details of the crystal structure investigation may be
obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur
wissenschaftlich-technische Information mbH, D-W-7514 EggensteinLeopoldshafen 2 (FRG) on quoting the depository number CSD-56037,
the names of the authors, and the journal citation.
[12] J. L. Atwood, W. E. Hunter, A. H. Cowley, R. A. Jones, C . A. Stewart, J.
Chem. Soc. Chem. Commiin. 1981,925.
(131 The bonding geometry of metallocenes of the divalent Group 14 elements
has been discussed for example for stannocene and its derivatives; compare P. D. Lickiss in Chemislry oj Tin (Ed.: P. G. Harrison), Blackie &
Son, Glasgow, 1989, Chapter 7.
[I41 M. J. Heek. C. Janiak, J. J. Zuckerman, J Am. Chem. SOC.1984.106,4259.
[15] N. Kuhn, E:M. Horn, R. Boese, D. Bliser, Chem. Ber. 1989, f22, 2275.
[I61 P. Jutzi, R. Dickbreder, J. Organomel. Chem. 1989, 373, 301.
(171 N. Kuhn, A. Kuhn, E.-M. Lampe, Chem. Ber. 1991, 124,997, and references cited therein.
Benzo-1,2,3-triselenolium Trifluoromethanesulfonate-a C,Se, Radical Cationic Salt
with Unusual Solid-state Structure**
By Gotthelf Wolmershauser* and Gert Heckmann
Ring compounds containing S atoms with a 77c electron
framework are often unusually stable.". 1' In contrast, there
are hardly any of the homologous Se compounds known.
However, we recently proved the existence of such an unstable compound with the radical 1. Compound 1 was
formed by the reduction of the corresponding cationic 67c
electron species.[31If the N atom in 1 is replaced by Se+,then
the benzo-l,2,3-triselenoliumradical cation 2 is obtained,
which contains a new 77c-electron heterocycle.
CAS Registry numbers:
2. 3760-56-3; 3, 140633-73-4; PbCI,, 7758-95-4.
[l] Compare N. Kuhn, Bull. SOC.Chim. Belg. 1990, 99, 707; J. Zakrezewski,
Heterocycles 1990,31, 383; D. L. Kershner, F. Basolo, Coord. Chem. Rev.
1987, 79, 279.
[2] Reviews: F. Mathey, J. Organomel. Chem. 1990, 400, 149; 0.J. Scherer,
Angebt. Chem. 1990, f02, 1137; Angew. Chem. Int. Ed. Engl. 1990, 29,
1104; W. Siebert, Pure Appl. Chem. 1988.60.1345; J. F. Nixon, Chem. Rev.
1988, 88, 1327: G. Schmid, Comments Inorg. Chem. 1985.4, 17.
(31 G. E. Herberich, U. Englert, M. Hostalek, R. Laven, Chem. Ber. 1991,
124, 17; P. Jutzi, A. Karl, P. Hofmann, Angew. Chem. 1980, 92, 496;
Angew. Chem. Inr. Ed. Engl. 1980, 19, 484, and references cited therein.
[4] Review: P. Jutzi, J. Orgunomet. Chem. 1990, 400, 1; P. Jutzi. Pure Appl.
Chem. 1990,62,1035; ibid. 1989.61, 1731; Adv. Organomet. Chem. 1986,
26, 217.
(51 P. Jutzi. D. Kanne. C. Kruger, Angew. Chem. 1986,98,163; Angew. Chem.
Inr. Ed. Engl. 1986, 25, 164.
[6] H. Wadepohl, H. Pritzkow, W. Siebert, Organometallics 1983,2, 1899; G.
Schmid, D. Zaika, R. Boese. Angew. Chem. 1985,97, 581 ; Angew. Chem.
Inr. Ed. Engl. 1985, 24. 602.
Angew. Chem. Int. Ed. Engl. 3 / (1992) No. 6
s Se .
To our knowledge 2 is the first selenium-centered radical
cation with a cyclic C2Se3unit. There are two possible synthetic routes for the preparation of 2. A reaction step which
occurs in both cases is the addition of Se to a Se-halogen bond
(Scheme 1). Compound 2-C1 is formed at room temperature
by the reaction of o-C,H,S~,CI,[~~(3) with two equivalents
of gray selenium in 72 % yield. Alternatively, (C,H,Se2),[41
[*] Dr. G. Wolmershauser, Dip1.-Chem. G . Heckmann
Fachbereich Chemie der Universitat
D-W-6750 Kaiserslautern (FRG)
[**I This work was supported by the Deutsche Forschungsgemeinschaft. We
thank Prof. Dr. D. Dormann and Dr. H. Winter, Physikalisches Institut
der Universitit Karlsruhe, for the magnetic measurements.
Verlagsgesellsrhafi mhH, W-6940 Weeinheim, 1992
OS70-0833/92/0606-0779 $3.50+.25/0
k2-“ +
(4) can be allowed to react with Se,CI, under the same reaction conditions. Compound 2-C1 is a dark blue solid, which
is almost insoluble in organic solvents Readily soluble salts
are obtained if the C1- is exchanged for complex anions such
as S0,CF; Thus, from the reaction of 2-CI with trimethyisilyl trifluoromethanesulfonate and subsequent extraction
with acetonitrile a deep violet solution of 2-S03CF, is
formed, from which gold-colored, metallic shiny crystals
precipitate on removal of the solvent
The X-ray crystal structure[51shows that 2-SO,CF, is
dimeric in the solid stateL6, (Fig 1 ) The five-membered het-
Fig. 2. Arrangement of Z-SO,CF, in the solid state.
acid as the solvent increases the signal intensity considerably,
which is an indication of a solvent-dependent dissociation
equilibrium. The ion pairs observed in the solid state are
probably more strongly dissociated in polar protic solvents
so that the coulombic repulsion between the radical cations
can become effective. Quite obviously the dimeric structure
of 2 is also favored in solution.
Experimental Procedure
Flg 1 Crystal structure of 2-S0,CF3 Selected bond distances [A] and angles
[“I Sel-Se2 2 298(5), Se2-Se3 2 293(5), Sel-CI 1 91(4), Se3-C2 1 88(3), Cl-CZ
1 41(4), Se4-Se5 2 280(5), Se5-Se6 2 276(5), Se4-C7 1.89(3), Se6-C8 1 85(3),
C7-CX 1 38(3), Sel-Se4 3 278(4), Se2-Se5 3 153(4), Se3-Se6 3 246(4), C1-SelSe2 99(1), Se3-Se2 Sel 97 2(2), C2-Se3-Se298(1). C7-Se4-Se5 98 9(8), Se6-Se5Se4 97 6(2). C8-Se6-Se5 96 9(9)
2-S0,CF3: A solution of Se,CI, (0.70 g. 3 mmol) in dichloromethane ( 5 mL)
was added dropwise to a yellow suspension of “[3,4][7,8]dibenzotetraselenocin”(0.72 g, 1.5 mmol)[4] in dichloromethane (30 mL) at room temperature. After 3h the gray-black reaction mixture was allowed to react with
trimethylsilyl trifluromethansulfonate (0.5 mL, 3 mmol). The gold, shiny microcrystalline solid was separated after l h, washed several times with
dichloromethane. and dried under vacuum; Yield 0.91 g (64%), m.p. 208 “C.
Received: December 19, 1991 [Z5079IE]
German version: Angew. Cliem. 1992, 104, 752
CAS Registry numbers:
2-CI. 140468-63-9; 2-S0,CF3. 140468-65-1; 3. 140468-66-2;4, 107658-48-0.
erocycle is almost planar (maximum deviation of the atoms
from the plane is 0.09 A) and coplanar to the C , ring. The
dimers are formed by two rings which are superimposed and
are arranged almost parallel to one another. This conformation allows almost identical interactions for all Se atoms and
thus, despite the Coulombic repulsion, an effective spin pairing between the two cations. The average Se-Se distance
between the monomeric units in the rings is 3.2 A, significantly longer than a Se-Se single bond (2.35 A); however, it
is also considerably shorter than the van der Waals distance
(4 A). Somewhat weaker Se . . . Se interactions between the
monomeric units (3.57 A and 3.76 8, in the direction of the
a axis, and 3.72 A along the c axis) additionally cause a cross
linkage of the planes (Fig. 2). Cation-anion interactions
( S e . . . O = 2.7-3.0 A), in which two oxygen atoms of two
trifluoromethanesulfonate anions bridge the four Se-Se
bonds of a dimer, contribute to the reduction of the coulombic repulsion of the cations.
The ESR spectrum of 2-S03CF, in acetonitrile shows a
singlet of low intensity (g = 2.0758 G) with a half-intensity
width of about 26.5 G. However, the use of trifluoroacetic
.c VCH Verla~~gesellschufimhH, W-6940 Weinheim. 1992
[l] R. J. Gillespie. J. P. Kent, J. F. Sawyer, fnorg. Chem. 1981, 20, 3784.
[2] T. S. Cameron, R. C. Haddon, S. M. Mattar, S. Parsons. J. Passmore, A. P.
Ramirez, J. Chrm. SOC.Chrm. Commun. 1991. 358.
[3] G. WolmerhBuser, W Kaim, G. Heckmann, A. Lichtblau, 2. Nahirforsch.
B, 1992. 47. 143.
[4] D. J. Sandman, J. C. Stark, L. A. ACdmpOrd, L. A. Samuelson, G. W. Allen,
S. Jansen, M. T. Jones. B. M. Foxmann, Mol. Cryst. Liq. Crysf. 1984.
107, 1.
[ 5 ] a) Z-SO,CF,: Gold. shiny crystals were obtained from acetonitrile; monoclinic, P2,lc. a =12.163(7), b =15.831(4), c =33.218(6) A. /I = 92.51(2)’,
I.’= 2542(2) A3, Z = 4.3615independent reflections(Mo,,: 1.5 ~ 8 ~ ).2 6
of which 1752 were observed with (1>20(I); 161 parameters, R = 0.099.
R , = 0.078. b) SHELXS-86 and SHELX-76 were used for the solution and
refinement and SCHAKAL-88 was used for drawing the structure. Further
details of the crystal structure investigation may be obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlich-technische Information mbH, D-W-7514 Eggenstein-Leopoldshafen 2 (FRG) on
quoting the depository number CSD-56079, the names of the authors. and
the journal citation.
[6] Also the results of magnetic measurements are consistent with this. The
surprisingly small Curie constant of C =1.24 x 1 0 - 3 e m u m o l ~ ’ K - ’indicates an antiferromagnetic spin pairing.
[7] However, stacks of monomers with a layer distance of 4.1 8, occur in crystals of 4,5-bis(trifluoromethyl)-l.2,3-trithioliumhexafluoroarsenate 121.
Angew. Chem. I n f . Ed. Engl. 31 (1992) N o . 6
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salt, c2se3, triselenolium, benz, structure, solis, methanesulfonates, state, unusual, radical, trifluoro, cationic
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