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Intramolecular Interaction between a Tropylium Ion and a Non-Neighboring Cyclopropane Ring.

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131 syn-1,6-Ethano-8,13-methano[l4~annulene,
which displays increased torsions in the annulene ring compared to in syn-1.6 :8,13-bismethano[l4]annulene was recognized, similarly to the anri- 1,6 :8,13-bismethano[ 141annulene, as being an olefinic molecule with fluxional x-bonds, E. Vogef,H.
M. Deger, P. Hebei, J. Lex, Angew. Chem. 92,943 (1980); Angew. Chem.
Int. Ed. Engl. 19. 919 (1980); H. Giinther. H. von Putfkamer.H . M.Deger,
P. Hebel, E. Vogel, ihid. 92, 944 (1980) and 19, 921 (1980).
(41 M . Balci. R. Schalenbach, E. Vogel, Angew. Chem. 93. 816 (1981); Angew. Chem. Int. Ed. Engl. 20, 809 (1981).
(51 J. Hine. D. C . Dufiey, J. Am. Chem. SOC.81, 1131 (1959); J. M . Birchall.
G. W. Cross, R . N. Haszeidine, Proc. Chem. SOC.(London) 1960, 81.
[61 For the hydrolysis of geminal allylic fluorides see: J. J. Drysdale, W. W .
Gilbert. H. K . Sinclair. W . H . Sharkey, J. Am. Chem. SOC.80, 3672 (1958);
J . D . Park, S. Cohen, J . R . Locher. ibid. 84, 2919 (1962).
[71 We thank Professor H. Gunther (Gesamthochschule Siegen) for the measurements.
[S] The bridge-bond angles measured in anfi-1.6 :8,13-bismethano[l4]annulene and (2) are 108.8 and 119.8" [9], respectively, and thus show remarkable conformity with those to be expected for sp3- and spz-hybridized carbon atoms, respectively.
I91 R. Destro. T. Pifati, M. Simonefta, Tetrahedron 36, 3301 (1980).
from the benzene derivatives, (7) through homologation
with diazomethane and a hydride ion abstraction sequence. Thus, for example, cyclopropanation of endo-benzotricycl0[3.2.2.0~~~]non-6-ene
(7a)13=lwith CH2N2 in the
presence of CuCl in CH2C12gave rise to a mixture of two
cycloheptatriene isomers (9a) and (IOa) in 28.4% yield. In
contrast, the same cyclopropanation of the exo-derivative
(7b)[3a1 and 9,10-benzopentacyclo[4.4.0.02~4.03~8.05~7]dec-9ene (benzosnoutene) ( 7 ~ ) ~led~ "to~ a mixture of all three
possible isomers, (Sb), (9b), and (lob) (239/0),and (8c), (9c),
and (I&) (25%), respectively. All of these isomers could be
separated by column chromatography on silica gel impregnated with 7% AgN03 (hexane i-benzene) and characterized by 'H-NMR spectroscopy.
Intramolecular Interaction
between a Tropylium Ion and
a Non-Neighboring Cyclopropane Ring[*']
By Tomoo Nakazawa, Keiji Kubo, Atsuko Okimoto,
Jun Segawa, and Zchiro Murata"'
Many examples of remote interaction between a cyclopropane ring and a non-neighboring carbonium ion center
are knowncTa1,
the best known example being the solvolysis
of the five norbornyl derivatives (1)-(5), whose relative
rates are 1, 1.7, lo9, lo", and lo", respectively[''. However,
attempts to observe the cation derived from (5) directly by
spectroscopic methods have been unsuccessful, because
the potential precursors are unstable in the acidic media
employedc2].
Herein we report the synthesis and some properties of a
series of compounds (6a)-(6c), in which the tropylium ion
and cyclopropane ring are incorporated in a bicyclo[2.2.2]octane. The tropylium ions (6) can be synthesized
Conversion of these cycloheptatrienes into the desired
tropylium ions was readily accomplished using trityl tetrafluoroborate in CH2C12:(6a)I4](yellow leaflets, mp 1267°C); (6b)['] (pale yellow prisms, mp 201-3 " C (decomp));
and ( 6 ~ (lemon-yellow
) ~ ~ ~
plates, mp 160.5 "C (decomp)).
In the tropylium ions (66) and (6c), the cyclopropane
and tropylium moieties are situated such that interaction
can occur via an edge of the three-membered ring: this is
not the case in (6a). The interactions are evident in the UV/
VIS spectra of (6a)-(6c) (Fig. 1). (6b)
= 900) and (6c)
[*] Prof. Dr. 1. Murata[+', K. Kubo, A. Okimoto, J. Segawa
Department of Chemistry, Faculty of Science, Osaka University
Toyonaka, Osaka 560 (Japan)
Prof. Dr. T. Nakazawa
Department of Chemistry, Medical University of Yamanashi,
Nakakoma-gun, Tamoho-mura, Yamanashi 409-38 (Japan)
['I Author to whom correspondence should be addressed.
["'I This work was supported by a Grant-in-Aid for Scientific Research (No
343007) from the Ministry of Education, Japan.
Angew. Chem. I n t . Ed. Engl. 20 (1981) No. 9
0 Verlag Chemie GmhH, 6940 Weinheim, 1981
i [nml0570-0833/81/0909-0813 $ 02.50/0
813
E = 2000)
~
~ exhibit
~
strong broad end-absorptions in the
long wavelength region, tailing out to 400 and 450 nm, respectively; this is not observed in the spectrum of the reference compound (I I). These absorptions undergo blueshifts upon changing the solvent to the more polar acetonitrile[*].These results, as well as the concentration independence of their intensities, suggest that the absorptions can
be assigned to intramolecular charge-transfer (CT)
bands"]. In contrast, (6a) only shows a weak absorption
( E ~ ~=
, ,370) in this region, a result of the weaker interaction
of the cyclopropane "side" with the "remote" tropylium
ion.
The intramolecular CT-interaction in (6a)-(6c) is also
reflected in their ground state properties e. g. pKR+-values
and their reduction potentials (Table 1).
(
Table 1. pK,-values
(6a)-(6c), and (11).
PKR*Ial
E1/2 Ibl
and reduction potential data for the tropylium ions,
8.60
- 0.450
8.68
-0.473
8.85
8.82
- 0.492
- 0.455
[a] Measured spectrophotometrically in 20% aqueous CH,CN. [b] vs. SCE.
Measured by polarography at 25 "C in CH3CN (25 "C, CH3CN, Et,NCIO, as
supporting electrolyte).
Although the dominant factor affecting the thermodynamic stability of the tropylium ion is the inductive effect
of the bicyclo[2.2.2]octane skeleton[7.'I, both the pK,+-Values and the reduction potentials increase, although only to
a small degree, with increasing charge-transfer interaction
in the order (6a), (6b), to (6c).
Studies of the possible interactions in the excited states
by MCD spectroscopy and MO (CNDO/S) calculations
are presently been undertaken"].
Received: October 8, 1980 [Z 848 IE]
German version: Angew. Chem. 93, 820 (1981)
zation, the "C-NMR data are more informative. Thus, comparison of
the "C-NMR data for tropylium ions, ( 6 4 (66). and (6c), with those reported for the corresponding benzo-analogs, (7a) [3al, (76) [3b], and (7c)
(51, indicates that (i) the ethano bridge carbons (C-3 and C-4) of both
(6a) and (6b), compared with those of (70) and (76). respectively, are
shifted upfield by ca. 2 ppm [6], (ii) the signals of C-l and C-6 in (6a)
also exhibit slight upfield shifts of 0.9 ppm and (iii) the signals of C-l
and C-6 in (66) and C-2, C-4, C-6, and C-8 in (6c) exhibit downfield shifts
of 0.7 and 2.8 ppm, respectively. These downfield shifts are indicative
of decreased electron densities at these carbon atoms a consequence of
the intramolecular CT-interaction in (66) and (6c).
IS] ( 7 ~ ) "C-NMR
:
(CDICN) 6=34.5 (C-1, 5), 37.7 (C-2, 4, 6, 8), 40.9 (C-3,
71, 125.1 (C-10, Il), 124.8 (C-9, 12), 144.1 (C-7a, 12a). The numbering
follows that in ( 6 ~ ) .
[61 Almost the same high-field shift (1.8 ppm) is observed if the signals of
the C atoms in the ethano bridges in (11) 171 and in the 6,9-dihydro-6,9ethanobenzotropylium ion are compared with the signals of the corresponding benzo-annelated derivatives.
[7] T. Nakatawa. Y. Niimoto. K . Kubo, I . Murata. Angew. Chem. 92. 566
(1980); Angew. Chem. Int. Ed. Engl. 19, 545 (1980).
[ti] Cf. T. Nakazawa, I. Murata. J. Am. Chem. SOC.99, 1996 (1977); T. Nakatawa, N. Abe. K. Kubo, I . Murata. Tetrahedron Lett. 1979, 4995; K.
Yamamura. K. Nakatsu. K . Nakao. T. Nakazawa, I . Murata, ibid. 1979,
4999.
[9] The newly appeared end-absorptions in (6a), (66). and (6c) also appear
in their MCD spectra and are interpreted, on the basis of the
MO(CNDO/S) method, to be due to the electronic transitions from the
cyclopropane to the tropylium-moiety. A. Tujiri, M. Hazano, K . Nakasuj i , T. Nakazawa, I. Murata, Rer. Runsenges. Phys. Chem., in press.
[lo] K. Takeuchi, Y. Yokomichi. T. Kurosaki, Y. Kimura, K. Komatsu. K.
Okamoto, Abstracts M33, 29th Symp. Org. React. Mechanisms, Osaka
1978.
A Triply Bridged Dicobalt Complex with Odd
Number of Electrons (Cd+)[**I
By Hans Heinz Karsch and Beatrix Milewski-Mahrla"'
Dinuclear complexes with bridging ligands and direct
metal-metal interaction, which contain an odd number of
electrons, are accessible in only a few exceptional cases
and/or by directed redox reactions"]. We report here on
the spontaneous formation of a novel, triply bridged dicobalt complex with the "mixed" oxidation state Co:+.
CAS Registry numbers:
(6a). 73745-17-2; (6b). 73701- 15-2; (Sc), 73701-17-4; (7a). 5933 1-32-7; (76).
59273-83-5; (7c). 29443-83-2; (86). 78805-35-3; (84 78805-36-4; (90). 7880537-5; (9b). 78854-31-6; ( 9 4 78805-38-6; (IOU), 78805-39-7; (lob), 78854-32-7;
(IOc), 78805-40-0; ( I l l 8 73701-21-0.
[I] a) Review: 1.Haywood-Farmer, Chem. Rev. 74, 315 (1974); b) H. Tanida, T. Tsuji. T.Irie. J. Am. Chem. SOC.89, 1953 (1967); M.A. Battiste, C.
L. Deymp. R . E. Pincock, J. Haywood-Farmer, ibid. 89, 1954 (1967); J.
Haywood-Farmer, R. E . Pincock. ibid. 91. 3020 (1969); H . Tanida, Acc.
Chem. Res. I , 239 (1968); P. K. Freeman, R. S. Raghauan. G. L. Fenwick, J. Am. Chem. SOC.94, 5101 (1972); R . M. Coates. J. L. Kirkpatrick,
ibid. 90,4162 (1968); 92, 4883 (1970).
121 See footnote 120 in [la].
[3] a) K. Kitahonoki, K . Sakurawi, K. Tori, M . Ueyama, Tetrahedron Lett.
1976. 263; b) L. A. Paquetfe, M. J . Kukla, J. C. Stowell. J. Am. Chem.
SOC.94. 4920 (1972).
141 (6a): 'H-NMR (CD2C12)6= -1.08 (IH, dt, J=7.6, 3.6 Hz, H-77,,,),0.23
(IH, dt, J=7.6, 7.6 Hz, H-7, ,,,,), 1.36-1.71 (4H, m, H-3,,,,, 4eyu,1,6),
2.62 (ZH, m, H-3,,,d,, 4e,,d<,),4.07 (ZH, m, H-2,5), 8.90-9.11 (SH, m, H8-12); "C-NMR (CD3CN) 6=2.0 (C-7), 10.3 (C-1,6), 24.0 (C-3,4), 43.2
(C-2,5), 151.5 (C-lo), 152.1 (C-8,12), 153.0 (C-9,11), 172.2 (C-5a, 12a).
(66): 'H-NMR (CD2CIZ)6= 1.10-1.50 (4H, m, H-I, 6,3,,, 4<*,,),1.571.77 (ZH, m, H-7O,,y,,,J, 1.94-2.19 (ZH, m, H-3e,,d0,4=".+,,),3.87-4.03
(2H, m, H-2, 5), 9.05 (5H,br, s, H-8-12); 'IC-NMR (CD3CN) 6 = 16.3
(C-71, 21.2 (C-1, 6), 21.8 ('2-3, 41, 42.9 (C-2, 5). 151.5 (C-lo), 152.9 (C-8,
12). 153.2 (C-9, 1 l), 178.7 (C-5a, 12a). (6c): 'H-NMR (CD2C12)6=1.962.18 (4H, m, H-2, 4, 6, 8), 2.93 (ZH, br. t, J = 5 . 0 Hz, H-I, 5), 4.33 (ZH,
quint, J=2.9 Hz, H-3, 7), 8.88-9.11 (SH, m, H-9-13); "C-NMR
(CD,CN)6=40.5 (C-2, 4, 6, 8), 41.3 ( G I , 5), 48.9 (C-3, 7), 150.3 (C-I]),
151.2 (C-9, 13). 152.2 (C-10, 12), 177.5(C-7a, 13a); the assignment of signals C-8, 12 and C-9, 11 in (6aJand (6b),as well as these of C 9, 13 and C10, 12 in (6c) could also be reversed. Although the 'H-NMR spectra of
(60). (66). and (6c) provide no useful information about charge delocali-
814
0 Verlag Chemie GmbH, 6940 Weinheim, 1981
In the series of isoelectronic complexes (1)-(3)['] the
orange cobalt([) compound (2) is distinguished by the fact
that it disproportionates in tetrahydrofuran (THF) solution-slowly at room temperature, rapidly above 40°Cto give the cobalt(1r) compound (4) (green crystals, dec.
> 115 " C ) and a product (5) decrystallizing as red-brown,
hexagonal platelets.
[(Me2PCH~PMe2)2(Me3P)Co]C1( 2 )
THF
.1
+40°C
[ ( M e z P C H z P M e z ) (Me3P)2CoCI2]
(4)
+
[ {(MeZPCH2PMez)(Me3P)Co}2PiVIe2]
i.7)
H. Karsch, DipLChem. B. Milewski-Mahrla
Anorganisch-chemisches
Institut der Technischen
Miinchen
Lichtenbergstr. 4, D-8046 Garching (Germany)
[*] Dr. H.
Universitat
[**I This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
0570-0833/81/0909-0814 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 20 (1981) No. 9
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