Shuzo Akiyama

Novel linear relation in the electronic spectra of α,ω-diarylpoly-ynes

Abstract Twelve series of diarylpoly-ynes [Ar(Cue5fcC) n Ar, n = 1 ∼ 6] bearing various kinds of aromatic terminal groups have been synthesized. It was found that the shifts of the longest-wavelength absorption maxima (λ L with the increase in the number of triple bonds ( n ) can be excellently expressed by the linear relationship: λ L = A n x + B The value of x varies from 1 to 2 [1 ⩽ x ⩽ 2] depending on the nature of the terminal groups and on the position of linking of the poly-yne chain, being x = 1 in the case of diphenylpoly-yne and x = 2 for 1.1′- and 9.9′-dianthrylpoly-ynes. The linear relation could be explained satisfactorily on the basis of HMO calculation assuming that the resonance integrals associated with triple and single bonds of the polyacetylene system should alter with n and be expressed by β cue5fcc = [1 + 1/( n + 4)]β and β cue5f8c = [1 - 1/( n + 4)]β, respectively. It was also shown that the wavenumbers of the longest-wavelength absorption maxima are in good correlation with the reactivity indices of the terminal aromatic hydrocarbon (Z r ) proposed by Brown.

Tetrakisdehydro[14]annuleno[16]annulene

Abstract Tetrakisdehydro[14]annuleno[16]annulene consisting of an aromatic bisdehydro[14]-annulene and an antiaromatic trisdehydro[16]annulene has been synthesized. The 1 H NMR parameters clearly indicate the strong paratropicity and diatropicity of the 16-membered and 14-membered rings, respectively.