The Structure of 2,5-Semiquinones derived from 1,6-Bridged [10] Annulenes

✍ Scribed by F. Gerson; K. Müllen; E. Vogel

• Book ID: 102858521
• Publisher: John Wiley and Sons
• Year: 1971
• Tongue: German
• Weight: 512 KB
• Volume: 54
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19710540411

✦ Synopsis

Abstract

ESR. spectra are reported for the radical anions of the diketones I and II (see below), recently prepared from 1, 6‐methano[10]annulene and its 11, 11‐difluoro‐derivative, respectively [1]. The π‐spin populations of I⊖ and II⊖ are shown to be incompatible with the structure A an enedione‐norcaradiene. Although the alternative structure B of a [10]annulenequinone is acceptable for both I⊖ and II⊖, the ESR. data is more satisfactorily rationalized in terms of a structure ‘intermediate’ to A and B. This is particularly true for the radical anion I⊖, for which the π‐spin populations suggest a structural ‘shift’ B → A relative to II⊖. Structures A and B were postulated [1] for the neutral diketones I and II, respectively.