A plasma grenade was a type of hand-thrown explosive device utilized by various cultures, one of the components of which was trinitrogen chloride.
In 2366, the Bajoran Resistance used a plasma grenade in an attempt to assassinate Gul Dukat aboard Terok Nor. Three Bajorans, Timor Landi, Ishan Chaye, and Jillur Gueta, where convicted and subsequently executed for the crime, although it was later discovered that they were not responsible. (DS9: "Things Past")
The Delta Quadrant pirate Tau sold a number of weapons, including plasma grenades. Captain Janeway witnessed him attempting to do so to a skeptical buyer, while shadowing him in an effort to retrieve technology stolen by Tau from the USS Voyager. (VOY: "Concerning Flight")