The term
scorpionate ligand refers to a tridentate
ligand which would bind to a metal in a
fac manner. The most popular class of scorpionates are the hydrotris(pyrazolyl)borates or
Tp ligands. These were also the first to become popular. These ligands first appeared in journals in 1966 from the then little-known DuPont chemist of Ukrainian descent, Swiatoslaw Trofimenko. Trofimenko called this discovery "a new and fertile field of remarkable scope".