title: Conformational control of [26]hexaphyrins(1.1.1.1.1.1) by meso-thienyl substituents.
abstract: Conformational preference and chemical stability of meso-aryl-substituted [26]hexaphyrins(1.1.1.1.1.1) ([26]ArH) depend upon meso-aryl substituents. Although only a planar and rectangular conformation (type-II conformation) has been identified for [26]ArH so far, we have demonstrated here that a different conformation with all the pyrroles pointing inward (type-I conformation) is preferred for [26]ArH (7 and 11-I) bearing small 2-thienyl or 3-thienyl substituents at 15- and 30-positions. Both type-I and type-II [26]ArH exhibit diatropic ring currents, reflecting aromatic character. Type-I [26]ArH, such as 7 and 11-I, have been shown to serve as an effective ligand for Pd(II) ions to provide bis-Pd(II) complexes 12 and 13 with N(3)C(1) coordination through facile C--H bond activation.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Suzuki
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Osuka