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Boussac, S. Un, T. Kargar-Grisel, G. Bouchoux, J. J. Girerd, Eur. J.
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Helical Sense Bias Induced by Point Chirality in
Cage Compounds**
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Mateo AlajarÌn,* Carmen Lopez-Leonardo,
[4] a) M. Lubben, A. Meetsma, E. C. Wilkinson, B. Feringa, L. Que, Jr.,
Angew. Chem. 1995, 107, 1610 1612; Angew. Chem. Int. Ed. Engl.
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Kooijman, A. L. Spek, R. Hage, B. L. Feringa, Chem. Commun. 1997,
1549 1550; d) C. Kim, K. Chen, J. Kim, L. Que, Jr., J. Am. Chem. Soc.
1997, 119, 5964 5965; e) G. Roelfes, M. Lubben, K. Chen, R. Y. N.
Ho, A. Meetsma, S. Genseberger, R. M. Hermant, R. Hage, S. K.
Mandal, V. G. Young, Jr., Y. Zang, H. Kooijman, A. L. Spek, L.
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Ho, G. Roelfes, B. L. Feringa, L. Que, Jr., J. Am. Chem. Soc. 1999, 121,
264 265.
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Angel Vidal, Jose Berna, and Jonathan W. Steed*
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Dedicated to Professor Jose Elguero
At the molecular level, helical chirality[1] is usuallya
consequence of strong conformational preferences around
covalent bonds. This is the case in molecular propellers, chiral
molecules possessing two or more subunits which can be
considered as ™blades∫ (e.g., aryl or spirocyclic rings), which
radiate from an axis of rotation (propeller axis).[2] Triaryl-
methanes are the most extensivelystudied structures of this
class.[3] Bicyclic organic compounds of local C3 symmetry,
constructed bylinking two propeller tripodal units exhibit this
type of chirality. However, this propeller shape has been
observed onlyfor a limited number of such compounds in
solution.[4] We have reported the preparation of several types
of C3 or pseudo-C3 symmetric, chiral macrobicyclic triphos-
phazides (e.g. 1a, Scheme 1), which possess propeller-like
[5] a) Y. Zang, T. E. Elgren, Y. Dong, L. Que, Jr., J. Am. Chem. Soc. 1993,
¬
115, 811 813; b) S. Menage, E. C. Wilkinson, L. Que, Jr., M.
Fontecave, Angew. Chem. 1995, 107, 198 199; Angew. Chem. Int.
Ed. Engl. 1995, 34, 203 205; c) J. Kim, E. Larka, E. C. Wilkinson, L.
Que, Jr., Angew. Chem. 1995, 107, 2191 2194; Angew. Chem. Int. Ed.
Engl. 1995, 34, 2048 2051; d) Y. Zang, J. Kim, Y. Dong, E. C.
Wilkinson, E. H. Appelman, L. Que, Jr., J. Am. Chem. Soc. 1997, 119,
4197 4205; e) A. Wada, S. Ogo, Y. Watanabe, M. Mukai, T. Kitagawa,
K. Jitsukawa, H. Masuda, H. Einaga, Inorg. Chem. 1999, 38, 3592
3593; f) T. Ogihara, S. Hikichi, M. Akita, T. Uchida, T. Kitagawa, Y.
Moro-oka, Inorg. Chim. Acta 2000, 297, 162 170; g) N. Lehnert,
R. Y. N. Ho, L. Que, Jr., E. I. Solomon, J. Am. Chem. Soc. 2001, 123,
8271 8290.
[5]
topologyin solution and in the solid state.
R
[6] The resonance Raman spectra of the deep blue species in DMF at
À608C with 607 nm laser excitation showed an isotope sensitive band
R
R
R
R
R
at 877 cmÀ1 which was shifted to 831 cmÀ1 bythe use of H 18O2,
N
2
N
suggesting the presence of a peroxo species.
CDCl3
N
[7] A. Adam, M. Mehta, Angew. Chem. 1998, 110, 1457 1459; Angew.
Chem. Int. Ed. 1998, 37, 1387 1388.
[8] R. Ugo, F. Conti, S. Cenini, R. Mason, G. B. Robertson, J. Chem. Soc.
Chem. Commun. 1968, 1498 1499.
333 K, 24 h
N
N
N
N
N
N
N
N
P
- 3 N2
N
P
N
N
P
P
P
P
CH3
CH3
[9] a) S. Hikichi, M. Akita, Y. Moro-oka, Coord. Chem. Rev. 2000, 198,
61 87, and references therein; b) N. Kitajima, T. Katayama, K.
Fujisawa, Y. Iwata, Y. Moro-oka, J. Am. Chem. Soc. 1993, 115, 7872
7873; c) A. V. Asselt, B. D. Santarsiero, J. E. Bercaw, J. Am. Chem.
Soc. 1986, 108, 8291 8293; d) G. Ferguson, P. K. Monaghan, M.
Parvez, R. J. Puddephatt, Organometallics 1985, 4, 1669 1674.
[10] a) T. Ookubo, H. Sugimoto, T. Nagayama, H. Masuda, T. Sato, K.
Tanaka, Y. Maeda, H. Okawa, Y. Hayashi, A. Uehara, M. Suzuki, J.
Am. Chem. Soc. 1996, 118, 701 702; b) Y. Dong, S. Yan, V. G.
Young, Jr., L. Que, Jr., Angew. Chem. 1996, 108, 673 676; Angew.
Chem. Int. Ed. Engl. 1996, 35, 618 620; c) K. Kim, S. J. Lippard, J.
Am. Chem. Soc. 1996, 118, 4914 4915.
[11] a) W. Micklitz, S. G. Bott, J. G. Bentsen, S. J. Lippard, J. Am. Chem.
Soc. 1989, 111, 372 374; b) I. Shweky, L. E. Pence, G. C. Papaefthy-
miou, R. Sessoli, J. W. Yun, A. Bino, S. J. Lippard, J. Am. Chem. Soc.
1997, 119, 1037 1042.
[12] There is no band overlapping with the DMF band at 865 cmÀ1; this was
confirmed bythe measurement of spectra in [D 7]DMF (see in
Figure 3d, e, and f).
a
b
R = H
R = Br
1
2
Scheme 1. Synthesis of 2 bydinitrogen expulsion from 1.
Herein, we report that, when compound 1a was kept at
333 K in CDCl3 solution for 24 h, it cleanlyconverted into tri-
l5-phosphazene 2a in 75% yield, by triple expulsion of
molecular N2 (Scheme 1). The dinitrogen expulsion from
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[*] Dr. M. AlajarÌn, Dr. C. Lopez-Leonardo, Dr. A. Vidal, J. Berna
¬
Departamento de QuÌmica Organica
Facultad de QuÌmica, Campus de Espinardo
Universidad de Murcia, 30100 Murcia (Spain)
Fax : (349)68-364149
[13] M. Aresta, I. Tommasi, E. Quaranta, C. Fragale, J. Mascetti, M.
Tranquille, F. Galan, M. Fouassier, Inorg. Chem. 1996, 35, 4254 4260.
[14] G. M. Sheldrick, SHELXS-86, A Program for Crystal Structure
Determination, Universityof Gˆttingen, Germany, 1986.
[15] teXsan: Crystal Structure Analysis Package, Molecular Structure
Corporation (1985 & 1992).
Dr. J. W. Steed
Department of Chemistry
King×s College London
Strand, London WC2R 2LS (UK)
Fax : (44)20-7848 2810
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[**] We thank the Direccion General de Investigacion-MCYT (Project
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BQU2001-0010), Fundacion Seneca-CARM (Projects PB/2/FS/01 and
PI-1/00749/FS/01), and Acedesa (a division of Takasago) for financial
support. J.B. also thanks the MECD for a fellowship. J.W.S. thanks the
EPSRC and King×s College London for diffractometer funding.
Supporting information for this article is available on the WWW under
Angew. Chem. Int. Ed. 2002, 41, No. 7
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
1433-7851/02/4107-1205 $ 20.00+.50/0
1205