Two polymorphs of aqua[N,N′-ethyl­enebis(salicylideneaminato-N,O)]oxovanadium(V) nitrate

The title compound, aqua­[bis­(salicyl­idene)­ethyl­enediamin­ato-O,N,N′,O′]­oxovanadium(V) nitrate, [VO(C₁₆H₁₄N₂O₂)(H₂O)]NO₃, crystallizes as two polymorphs in the triclinic and monoclinic crystal systems. In both, the V atom has a distorted octahedral coordination geometry with a long V—O_water bond trans to V=O. The coordinated water mol­ecules are hydrogen bonded to the nitrate ions so that pairs of cations are linked to give neutral centrosymmetric dimers. The V=O and V—O_water distances are 1.598 (2) and 2.257 (2) Å, respectively, in the triclinic form, and 1.588 (3) and 2.230 (3) Å, respectively, in the monoclinic form. In the triclinic form, the dimers pack so that the salen [bis(salicyl­idene)ethylenediaminate] ligands are parallel to each other, whereas in the monoclinic form, which is the denser, there is a herring-bone arrangement.