A series of p,p‘-disubstituted 7-phenyl-7-(2-fluorophenyl)norbornanes 5xy has been prepared, and the barrier (ΔG #) to 160° libration around the 2-fluoroaryl-norbornane bond has been measured by DNMR. There is spectroscopic evidence of strong homoconjugative and charge-transfer (CT) interactions between both aryl groups of 5xy. However, the relationship between ΔG # and the nature of the substituents X and Y is accounted for only by electrostatic interactions between both aryl groups in the ground state as well as in the transition state of the libration. Therefore, the notion of CT and aromatic homoconjugation as strong attractive forces between aryl groups should be definitively rejected.

composition of donor : acceptor = 1 : 0.4, its upper bands are not half-filled. Whereas all other k-type superconductors have the composition of donor : acceptor = 2 : 1 and therefore, half-filled upper bands. The deviation from halffilling makes the on-site Coulomb repulsion comparatively unimportant; this stabilizes the metal state, but is disadvantageous with respect to superconductivity. [15] The same situation has been found in (EOET±TTP) 3 AsF 6 , [5b] and (CH± TTP)(I 3 ) 0.31 . [5c] In summary, we have found a k-type organic metal based on a newly prepared TTP derivative CPEO±TTP. To our knowledge, there is no report on metallic k-type salt base on ethylenedioxy-substituted TTF. [16] In contrast, CPEO± and EOET±TTP afford k-type salts retaining metallic conductivity down to low temperature. Therefore, combination of TTP framework and ethylenedioxy substituent would be suitable for exploring new k-type metals. The preparation of radical-cation salts based on the other ethylenedioxy substituted TTPs is actively in progress. Experimental CPEO±TTP: Red microcrystals; m.p. = 246±247 C (decompose.); 1 H NMR (270 MHz, CS 2 -[ 2 H 6 ]benzene) d 4.17 (s, 4H), 2.49±2.56 (m, 4H), 2.35± 2.45 (m, 2H); I.R. (KBr) u (cm ±1 ) 1653, 1452, 1168. (CPEO±TTP)(SbF 6 ) 0.4 : C 15 F 2.4 H 10 O 2 S 8 Sb 0.4 , M = 573.02, monoclinic, space group C2/c, a = 45.144(3), b = 7.984(4), c = 10.999(5) . b = 99.72 (2), V = 3907(2) 3 , Z = 8, D c = 2.235 g/cm 3 , Mo Ka radiation, l = 0.71069 , m = 23.06 cm ±1 , F(000) = 2576.00. The data were collected on a Rigaku AFC7R diffractometer equipped with graphite monochromated Mo Ka radiation using the o±2y scan technique to a maximum 2y of 55. The structure was solved by direct methods and refined by full-matrix least squares analysis (anisotropic for non-hydrogen atoms) to R = 0.065, R w = 0.070 for 1359 observed (I ³ 3s (I)) reflections from 4816 unique data. All calculations were performed using the teXsan crystallographic software package of Molecular Structure Corporation. Atomic coordinates, bond distances and angles, and thermal parameters have been deposited at the Cambridge Crystallographic Data Center.

The influence of preorganised 7,7-diphenylnorbornane in the stability (Ka) of host-guest complexes as well as in the determination of the energy of edge-to-face aromatic interactions has been investigated. The guest molecules studied bind more strongly with hosts that contain the cofacial 7.7-diphenylnorbornane subunit than with similar hosts that have a 1,1-diphenylcyclohexane subunit. On the other hand, the value of the edge-to-face aromatic interactions calculated for our complexes (-0.2 +/- 0.6 kJmol(-1)) is significantly lower (by a factor of seven) than the one previously reported in the literature. This result highlights the importance of entropic factors in the determination of weak noncovalent interactions.

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The reaction of hypervalent tin reagents (n-Bu 4 N) + (R 1 3 SnF 2 ) -(R 1 ) aryl, benzyl) with vinyl and aryl triflates affords the corresponding cross-coupling products in good yields and short reaction times. The method described represents an important improvement over the classical Stille reaction. The hypervalent reagents are easily prepared by reaction of R 1 3 SnF and n-Bu 4 NF.