No abstract

A new donor, the C-F unit, can be added to the field of host-guest chemistry. The interaction between fluorine atoms and a potassium ion was proven with the fluorine-containing cage compound 1 as a host. The six fluorine atoms of K ⊂1 are coordinated to K in a distorted octahedral fashion.

Ein neuer Donor für die Wirt‐Gast‐Chemie: die C‐F‐Einheit. Die Wechselwirkungen zwischen Fluoratomen und einem Kaliumion wurden an einem Wirt/Gast‐Komplex mit der fluorhaltigen Käfigverbindung 1 als Wirt nachgewiesen. Die sechs Fluoratome in K+⊂1 koordinieren das K+‐Ion verzerrt oktaedrisch.

The conformational isomers (syn and anti) of 9,18-difluoro-2,11-diaza[3.3]metacyclophane, 1, were isolated at ambient temperature and each was identified by 19F NMR spectra. The anti isomer gradually converted to the syn isomer in solution, and kinetic measurements of this conversion afforded the Arrhenius activation energy, E a = 24.8 ± 0.9 kcal/mol, in acetonitrile. The difference in thermodynamic stability of the syn and anti isomers in DMSO was estimated to be ca. 2 kcal/mol (298 K) on the basis of the variable temperature NMR method. The three conformational isomers, boat−boat, chair−boat, and chair−chair, are present in the syn isomer in solution. The relative stability order of the three isomers, boat−boat, chair−boat, chair−chair, is estimated by the 1H- and 19F NMR spectra. The boat−boat isomer is predominant at low temperatures, but the ratio of the other two isomers, chair−boat and chair−chair, is gradually increased as the temperature is raised.

A novel macrocyclic cage compound with four thiophene rings was synthesized following a one-step procedure and then structurally converted by disulfurization.