Vanadate in the context of "Resonance (chemistry)"

In chemistry, a vanadate is an anionic coordination complex of vanadium. Often vanadate refers to oxoanions of vanadium, most of which exist in its highest oxidation state of +5. The complexes [V(CN)₆] and [V₂Cl₉] are referred to as hexacyanovanadate(III) and nonachlorodivanadate(III), respectively.

A simple vanadate ion is the tetrahedral orthovanadate anion, VO3−4 (which is also called vanadate(V)), which is present in e.g. sodium orthovanadate and in solutions of V₂O₅ in strong base (pH > 13). Conventionally this ion is represented with a single double bond, however this is a resonance form as the ion is a regular tetrahedron with four equivalent oxygen atoms.