Solutions of both 2 and 15 are extremely sensitive to air. They turn a deep purple color (A,= 530-540 nm) that persists for a few hours and then fades to colorless.(The absorbance at 530-540 nm also then disappears.) Attempts to elucidate the structure of the transient intermediate were unsuccessful, but TCNP or its radical anion could not be recognized.(A 6.15-mM acetone solution of 15, deep purple after exposure to air for 5 h, showed nitrile ...