Structure-property relationships of a tetrapyrrolidinyl PNP-lariat ether and its complexes with potassium, sodium, and silver cations

Spectral properties of the tetrapyrrolidinyl PNP-lariat ether, L, and its c omplexes with K+, Na+, and Ag+ were investigated. Crystal structures of L a nd its complex with potassium iodide [KL]I were determined. Protonation con stants of the ligand and formation constants of its complexes with Ag+, K+, and Na+ in aqueous solutions were detennined. H-1 NMR, P-31 NMR, FTIR, and ESIMS spectra as well as potentiometric measurements indicate that complex ation of Ag+ involves participation of the polyether oxygen donors and the endocyclic nitrogen atom of the cyclophosphazene ring. On the other hand, f or complexation of K+ and Na+, only polyether oxygen atoms are involved. Th e latter conclusion is confirmed in the solid-state structure of the [KL]I complex.