Microsolvation of K⁺/15-crown-5in water, methanol and acetonitrile An abinitiotheoretical study with spectroscopic measurements on the acetonitrile solutions

Abstract

An abinitio computational study of the formation of complexes of the potassium ion with the crown ether 15-crown-5 in three solvents, water, methanol and acetonitrile, is reported. The binding energy of the complexes has been analysed to identify contributions from structural changes and pair-wise interactions. The importance of the variation of the ion/solvent contribution to the binding energy in different solvents has been established. Reaction schemes have been investigated in which ion/solvent clusters interact with the crown ether to form complexes containing one crown ether molecule or sandwich complexes with two crown ether molecules. The relative importance of the two kinds of complex in the three solvents has been studied. New spectroscopic (IR and ¹³C NMR) data has been obtained on the acetonitrile solutions which can be interpreted within the general scheme of the theoretical calculations.