novel 2 , 3 , 5 - trisubstituted - 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxides have been found to have herbicidal activity . these 1 , 2 , 3 , 5 - thiatriazolidin - 4 - one - 2 - oxides are prepared by reacting an n - aminourea and thionyl chloride .