For most of the studied substituted aromatic compounds the Cs cation is preferentially attached to the carboxyl (-COOH) or hydroxyl (-OH) groups via an electrostatic interaction with the lone-pair electrons on electronegative oxygen atoms.
in the complex, the cesium cation may form stable bidentate-type chelate complexes with ligands that have adjacent functional groups with lone-pair electrons.
the [sigma]-type binding (with the lone-pair electrons of electronegative atoms of substituent groups) arises.