MACROCYCLIC [4N-HUCKEL AROMATIC SYSTEMS UP TO N = 9 AND [4N] ANTIAROMATIC SYSTEMS UP TO N = 10 - HOMOLOGOUS SEQUENCES FROM TETRAEPOXY[24]ANNULENE(2.0.2.0) TO TETRAEPOXY[40]ANNULENE(12.0.12.0) AND FROM THE TETRAOXA[22]PORPHYRIN(2.0.2.0)- TO THE TETRAOXA[38]PORPHYRIN(12.0.12.0)-DICATION(2])

Tetraepoxy[32]annulene(8.0.8.0) 3, tetraepoxy[36]annulene(10.0.10.0) 4 , and tetraepoxy[40]annulene(12.0.12.0) 5 are synthesized and oxidized to give the 'tetraoxa [30]-', 'tetraoxa [34]-', and 'tetraoxa[38]porp hyrin' dications 8-10. The annulenes as well as the 'porphyrins' are m ixtures of at least two different configurational isomers, which can b e analyzed by H-1-NMR techniques. Together with systems described alre ady earlier, a complete homologous sequence from tetraepoxy[24]annulen e(2.0.2.0) to tetraepoxy[40]annulene(12.1.12.0) and from 'tetraoxa[22] porphyrin(2.0.2.0)' to 'tetraoxa[38]porphyrin(12.0.12.0)' dications ar e available for the First time. The UV/VIS-absorption maxima in the an nulene series are shifted to longer wavelengths with an increment of 1 2 nm per additional C=C bonds, and the Delta delta values of the H-1-N MR spectra demonstrate a decreasing paratropic character (Delta delta = 5.97 (1), 2.80 (3), and 4.23 ppm (4)). The averaged lambda(max) valu es of the Sorer bands of the 'tetraoxaporphyrin' dications show a line ar bathochromic shift with an increment Delta lambda of 58 nm per two additional double bonds, the absorptions of the most intensive Q-bands also increase linearly with an increment of ca. 160 nm. The Delta del ta values of the H-1-NMR spectra of the 'tetraoxaporphyrin' dications are increasing with the ring size (Delta delta = 24.04 (7a) to 25.17 ( 9a) ppm), respectively, decreasing (Delta delta = 21.55 (6) to 21.50 ( 9b) ppm) with a small maximum of 22.60 ppm for 7b, depending on the co nfiguration of the isomers. The results confirm the antiaromatic chara cter of the annulenes with up to 40 pi electrons and the aromatic char acter of the 'tetraoxaporphyrin' dications with up to 38 pi electrons.