Polymer-like Structures of LiSCN, NaSCN, KSCN, RbSCN, and CsSCN Complexes with an Armed Monoaza-15-crown-5 Ether Bearing a 3‘,5‘-Difluoro-4‘-hydroxybenzyl Group

Structures of LiSCN, NaSCN, KSCN, RbSCN, and CsSCN complexes with 3‘,5‘-difluoro-4‘-hydroxybenzyl-armed
monoaza-15-crown-5 ether (5) were investigated. The Li+ and Na+ complexes are (1:1)n polymer-like complexes
bridged by hydrogen bonding. On the other hand, the K+, Rb+, and Cs+ complexes are polymer-like complexes
bridged by the fluorine atoms of the side arms. The titration calorimetry and 19F NMR titration experiments suggest
that one or both fluorine atoms along with the oxygen atom of the phenolic OH group coordinate to the alkali metal
ions incorporated in the crown part of a second armed ligand to give polymer-like complexes in solution. The
FAB-MS data indicated that larger alkali metal ions form more stable polymer-like complexes.