Janusz Grobelny

Characterization of potassium and sodium-potassium alloy solutions containing metal anions and complexed cations by means of NMR and ESR techniques.

The influence of a complexing agent, kind of solvent and temperature on the stability and ionic composition of potassium and sodium-potassium alloy solutions containing metal anions and complexed cations as well as solvated electrons are discussed basing on the analysis of alkali metal NMR and ESR spectra. Surprisingly it seems that the stability of metal solutions in tetrahydrofuran at ambient temperature is inversely proportional to the durability of K+ complex in the case of five studied ligands. The most stable metal solutions were obtained using 15-crown-5. It was shown that the characteristic blue colour of metal solutions is not connected with the presence of solvated electrons but with metal anions.

A 39K NMR study of potassium solution in tetrahydrofuran containing cryptand[2.2.2]

Abstract By means of 39 K NMR spectroscopy the presence of potassium anions and complexed potassium cations in blue potassium solutions in THF containing cryptand[2.2.2] was evidenced. Spin-lattice and spin-spin relaxation was studied in the temperature range 178–238 K. The comparison of relaxation behaviour of the investigated system with that of potassium solutions containing 18-crown-6 or tetraglyme instead of cryptand[2.2.2] revealed the major influence of the complexing agent on interactions of K + with its counterion.