A thiosemicarbazone is an organosulfur compound with the formula HNC(S)NHN=CR.  Many variations exist, including those where some or all of the NH centers are substituted by organic groups.  Thiosemicarbazones are usually produced by condensation of a thiosemicarbazide with an aldehyde or ketone:
: HNC(S)NHNH  +  O=CR  →    HNC(S)NHN=CR  +  HO
In terms of their chemical structures, the CSN3 core atoms are coplanar.