Inert Carbon Free Radicals. 14. Synthesis, Isolation, and Properties of Two Strongly π−π Interacting Mixed-Valence Compounds: The Perchloro-4,4‘-ethynylenebis(triphenylmethyl) Anion Radical Potassium (18-Crown-6) Salt and the Perchloro-α,α,α‘,α‘-tetraphenyl-p-xylylene Anion Radical Tetrabutylammonium Salt | Publicación