The idea of transforming a classical arene, by “bridging,” into a [4n+2]annulene has been further extended to the phenanthrenes. The spectroscopic data and structural parameters for the title compound 1 reveal it to be a borderline case, with respect to its π‐electron structure, for an aromatic molecule.

Pure Appl. Chem. 58 (1986) 15; b) the same holds for the bridged [14]annulenes with "azupyrene perimeter" (annelated systems of two azulene

Ein Lehrbuchbeispiel dafür, daß ein [4n + 2] Annulen völligen Aromatizitätsverlust erleidet, wenn auch nur eine CC‐Bindung extrem verdrillt ist, gibt die Titelverbindung 1. Dieses „anti‐Bishomophenanthren”︁ und sein im vorigen Beitrag beschriebenes syn‐Isomer äquilibrieren nicht.

046 ChemInform Abstract (UV/VIS, polarized fluorescence, MCD; X-ray analysis of (I), (III), and (IV): P1 (Z = 8); P21/c (Z=4); Pbca (Z = 8)).

der Organolutetium-Phosphor-Bi!dungen (erstmals gemessen) betragen 2.782 und 2.813 A.[**I Diese Arbeit wurde von der Deutschen ForschungsgemeinschafI gef6r-Angew. Chem. 98 (1986) Nr. 8 0 VCH Verlagsgeselhchaft mbH. D-6940 Weinheim. 1986 0044-8249/86/08M-0729 S 02.50/0

No abstract

Since reductive coupling of 1,1'‐bis(cycloheptatrienyl)‐6,6'‐dicarbaldehyde leads stereospecifically to the syn‐isomer (X), the anti‐dihydrobismethano‐annulene (IX) is expected to be an appropriate intermediate for the synthesis of the title compound (XI).

The idea of transforming a classical arene, by “bridging,” into a [4n+2]annulene has been further extended to the phenanthrenes. The spectroscopic data and structural parameters for the title compound 1 reveal it to be a borderline case, with respect to its π‐electron structure, for an aromatic molecule.