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Volumn , Issue 18, 2004, Pages 3763-3771

Molecular "iron maidens": Ultrashort nonbonded contacts in cyclophanes and other crowded molecules

Author keywords

Cyclophanes; Intramolecular interactions; Noncovalent interactions; Strained molecules

Indexed keywords

BENZENE DERIVATIVE; CHLORINE; CYCLOPHANE DERIVATIVE; FLUORINE; FUNCTIONAL GROUP; NITROGEN; PHOSPHORUS; POLYCYCLIC AROMATIC HYDROCARBON; SULFUR;

EID: 4644297741     PISSN: 1434193X     EISSN: None     Source Type: Journal    
DOI: 10.1002/ejoc.200400183     Document Type: Short Survey
Times cited : (49)

References (65)
  • 1
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    • The conceptual chemistry of cyclophanes
    • (Eds.: P. M. Keehn, S. M. Rosenfeld), Academic Press: New York
    • J. F. Liebman, The Conceptual Chemistry of Cyclophanes. In Cyclophanes (Eds.: P. M. Keehn, S. M. Rosenfeld), Academic Press: New York, 1983; vol. 1, pp. 23-68.
    • (1983) Cyclophanes , vol.1 , pp. 23-68
    • Liebman, J.F.1
  • 6
    • 4644228413 scopus 로고    scopus 로고
    • note
    • The extensive CSD searches performed for this review clearly show that it is much easier for functional groups to approach an aromatic ring from the side (and thus away from the π-cloud). All contacts cited in this work involve atoms that lie above the ring, as defined strictly by this imaginary prism whose edges are normal to the mean plane of the aromatic ring.
  • 7
    • 0006678756 scopus 로고
    • Crystal structures of cyclophanes
    • (Eds.: P. M. Keehn, S. M. Rosenfeld), Academic Press: New York
    • P. M. Keehn, Crystal Structures of Cyclophanes, In Cyclophanes (Eds.: P. M. Keehn, S. M. Rosenfeld), Academic Press: New York, 1983, vol. 1, pp. 69-238.
    • (1983) Cyclophanes , vol.1 , pp. 69-238
    • Keehn, P.M.1
  • 10
    • 4644312331 scopus 로고    scopus 로고
    • note
    • In order to keep the typography simple, triple hyphens will indicate nonbonded contacts between groups (e.g. H-Ar, O-C), but short hyphens will be used for covalent bonds (e.g. C-H, C-O).
  • 11
    • 4644317294 scopus 로고    scopus 로고
    • note
    • C-H bond lengths are systematically underestimated by X-ray crystallography because hydrogen atoms have no core electrons, and the peak of the hydrogen electron density in a covalent C-H bond is displaced slightly toward the carbon.[13] For this reason, C-H bond lengths are often observed to be about 0.96 Å in X-ray structures, and in cases where the hydrogen positions are not refined, riding models which employ similar distances are used. In this review, in order to give more nearly accurate nonbonded distances involving hydrogen atoms, the C-H bond lengths have been "improved"; that is, the bond has been lengthened along the observed C-H bond vector to the standard values observed for that type of bond in neutron diffraction experiments: 1.083 Å for aromatic C-H, 1.092 Å for methylene C-H, and 1.099 Å for methine C-H.[14]
  • 12
    • 4644247684 scopus 로고    scopus 로고
    • note
    • Nonbonded distances involving aromatic rings have been reported in a variety of ways, some of which I illustrate for compound 3. In Hanson's original report[9] of the crystal structure, in which a C-H bond length of 0.98 Å was observed for the critical hydrogen, he says, "... C(8) lies only 2.71 Å, and H(8) only 2.16 Å, from the plane of the unsubstituted atoms of the para-bridged ring." This was mistranslated into Keehn's review of cyclophane structures[7] as "... 2.71 and 2.16 Å, respectively, from the mean plane of the para-bridged ring." In fact, when the mean plane of the ring is used (all six carbons, not just the unsubstituted ones), the distance is calculated to be 2.08 Å. When an improved[11] C-H bond length of 1.083 Å is also used, the distance to the mean plane drops to 2.03 Å. Finally, the distance of the (improved) hydrogen from the center (or, more properly, the centroid) of the benzene ring is 2.11 Å. This last measure is perhaps the least ambiguous, and it is the distance most often quoted in this review.
  • 16
    • 0000560130 scopus 로고    scopus 로고
    • For an excellent review of in, out isomerism, see: R. W. Alder, S. P. East, Chem. Rev. 1996, 96, 2097-2111.
    • (1996) Chem. Rev. , vol.96 , pp. 2097-2111
    • Alder, R.W.1    East, S.P.2
  • 21
    • 3743092717 scopus 로고
    • refcode: VAGFIS
    • [21a] T. K. Vinod, H. Hart, J. Am. Chem. Soc. 1988, 110, 6574-6575 (refcode: VAGFIS).
    • (1988) J. Am. Chem. Soc , vol.110 , pp. 6574-6575
    • Vinod, T.K.1    Hart, H.2
  • 33
    • 4644296144 scopus 로고    scopus 로고
    • note
    • The Si-H bond length was improved to the standard value of 1.48 Å. [30]
  • 37
    • 0343624962 scopus 로고
    • Synthesis and properties of heterophanes
    • (Eds.: P. M. Keehn, S. M. Rosenfeld), Academic Press: New York
    • W. W. Paudler, M. D. Bezoari, Synthesis and Properties of Heterophanes, in Cyclophanes (Eds.: P. M. Keehn, S. M. Rosenfeld), Academic Press: New York, 1983, vol. 2, pp. 359-441.
    • (1983) Cyclophanes , vol.2 , pp. 359-441
    • Paudler, W.W.1    Bezoari, M.D.2
  • 54
    • 0033597725 scopus 로고    scopus 로고
    • refcodes: CIPSID, CIPSUP, HAKQOZ01
    • S. Dell, D. M. Ho, R. A. Pascal Jr., J. Org. Chem. 1999, 64, 5626-5633 (refcodes: CIPSID, CIPSUP, HAKQOZ01).
    • (1999) J. Org. Chem. , vol.64 , pp. 5626-5633
    • Dell, S.1    Ho, D.M.2    Pascal Jr., R.A.3
  • 55
    • 4644247683 scopus 로고    scopus 로고
    • private communication to the CSD (refcode DIXQAC)
    • M. Nieger, S. Bartram, F. Vögtle, private communication to the CSD, 2000 (refcode: DIXQAC).
    • (2000)
    • Nieger, M.1    Bartram, S.2    Vögtle, F.3
  • 60
    • 85064390241 scopus 로고
    • refcode: WAJZOW
    • H. Buchholz, A. de Meijere, Synlett 1993, 253-255 (refcode: WAJZOW; there are some errors in the CSD coordinates; however, Prof. de Meijere kindly provided correct coordinates for this work).
    • (1993) Synlett , pp. 253-255
    • Buchholz, H.1    De Meijere, A.2


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.