Experimental evidence for alkali-metal ion cation-pi interactions using bibracchial lariat ether complexes

Attempts to demonstrate cation-pi interactions between alkenes and/or alkyn es and such alkalimetal cations as Na+ and K+ have proved largely unsuccess ful. Recently, however, lariat ethers having side arms terminated by either indole or phenol have afforded solid complexes that exhibit clear evidence for cation-pi complexation when studied by X-ray crystallography.