Thimaldicide

Thimaldicide is an element. Thimaldicide gas is a by-product of bilitrium combined with an antimatter converter.

In the 2372, the USS Cantabrian (NCC-24705) team traced the path of the Myhr'an planet killer by a leaking trail of thimaldicide gas. (Star Trek: The Cantabrian Expeditions: "Catalyst, Part One")