Chemical constitution and activity of bipyridinium herbicides. Part XIV. Reduction potential and herbicidal activity of 4,4′‐(1,3,4‐thiadiazole‐2,5‐diyl)‐ and 4,4′‐(1,3,4‐oxadiazole‐2,5‐diyl)bis(1‐methylpyridinium) diiodides

The diquaternary salts 4,4′‐(1,3,4‐thiadiazole‐2,5‐diyl)bis(1‐methylpyridinium) diiodide and 4,4′‐(1,3,4‐oxadiazole‐2,5‐diyl)bis(1‐methylpyridinium) diiodide are reduced in aqueous solution in the p H range 5.4‐8.0 to radical cations at a potential (Eo) of ‐0.39 V and ‐0.48 V, respectively. Their activity as herbicides is reported.