| Compound | Shape of the envelope | Range of the envelope (cm−1) | Shape of the curve below 1100 (cm−1) |
| Pinacyanol chloride | Symmetric triangular distribution | 650 - 1650 | Indirect transition |
| Pinacyanol chloranil (PC-Cl) | Imperfect nesting for cosinusoidal gap | 650 - 1700 | Inverted parabola |
| (PC-Cl)-DDQ | Imperfect nesting for cosinusoidal gap | 700 - 1700 | Inverted parabola |
| (PC-Cl)-TCNQ | Imperfect nesting for cosinusoidal gap | 800 - 1700 | Indirect transition |
| (PC-Cl)-TCNE | Not observed | - | Monotonous increase and plateau |