COMPLEXATION OF TROPYLIUM IONS WITH CROWN-ETHERS AND ACYCLIC POLYETHERS EXAMINED BY FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY

The molecular complex formation of six macrocyclic and six acyclic pol yethers with tropylium and 4-methoxyphenyltropylium tetrafluoroborates was observed and characterized in the gas phase by Fast atom bombardm ent mass spectrometry (FABMS), to obtain information on intrinsic mole cular interactions in the absence of the complicating effect of solvat ion, The stoichiometry of the complexes was assessed on the basis of c orresponding peaks in FAB mass spectra, In addition to the expected 1: 1 complexes between polyether and tropylium ion, some 2:1 complexes we re also Formed, The stability order of selected complexes was studied in competition experiments, The complexation equilibrium constant and thermodynamic parameters for the interaction of dibenzo-18-crown-6 wit h tropylium ion were determined in 1,2-dichloroethane solution by UV-v isible spectrophotometry, Complexation of polyethers with tropylium sa lts has not been reported previously.