Generation and direct observation of the thioxanthenyl and N-methyl acridinyl anions; A family of stable, paratropic, "4N" π-excessives

Article abstract of DOI:10.1016/0040-4039(80)80167-5

The title, thermally stable, heterocarbanions (2a, 2b) were generated upon respective exposure of conjugate acids 4(a,b) to a KNH₂/liq. NH₃ system and were shown (NMR) to possess (2a more than 2b) distinct elements of paratropicity.