In aqueous solution, vanadium(V) forms an extensive family of oxyanions as established by ⁵¹V NMR spectroscopy.
The interrelationships in this family are described by the predominance diagram, which shows at least 11 species, depending on pH and concentration.
The tetrahedral orthovanadate ion, VO³⁻
₄, is the principal species present at pH 12–14.
Similar in size and charge to phosphorus(V), vanadium(V) also parallels its chemistry and crystallography.
Orthovanadate VO³⁻
₄ is used in protein crystallography to study the biochemistry of phosphate.
The tetrathiovanadate [VS₄]³⁻ is analogous to the orthovanadate ion.

At lower pH values, the monomer [HVO₄]²⁻ and dimer [V₂O₇]⁴⁻ are formed, with the monomer predominant at vanadium concentration of less than c. 10⁻²M (pV > 2, where pV is equal to the minus value of the logarithm of the total vanadium concentration/M).
The formation of the divanadate ion is analogous to the formation of the dichromate ion.
As the pH is reduced, further protonation and condensation to polyvanadates occur: at pH 4-6 [H₂VO₄]⁻ is predominant at pV greater than ca.
4, while at higher concentrations trimers and tetramers are formed.
Between pH 2-4 decavanadate predominates, its formation from orthovanadate is represented by this condensation reaction:
10 [VO₄]³⁻ + 24 H⁺ → [V₁₀O₂₈]⁶⁻ + 12 H₂O
In decavanadate, each V(V) center is surrounded by six oxide ligands.
Vanadic acid, H₃VO₄ exists only at very low concentrations because protonation of the tetrahedral species [H₂VO₄]⁻ results in the preferential formation of the octahedral [VO₂(H₂O)₄]⁺ species.
In strongly acidic solutions, pH < 2, [VO₂(H₂O)₄]⁺ is the predominant species, while the oxide V₂O₅ precipitates from solution at high concentrations.
The oxide is formally the acid anhydride of vanadic acid.
The structures of many vanadate compounds have been determined by X-ray crystallography.

Vanadium(V) forms various peroxo complexes, most notably in the active site of the vanadium-containing bromoperoxidase enzymes.
The species VO(O)₂(H₂O)₄⁺ is stable in acidic solutions.
In alkaline solutions, species with 2, 3 and 4 peroxide groups are known; the last forms violet salts with the formula M₃V(O₂)₄ nH₂O (M= Li, Na, etc.),
in which the vanadium has an 8-coordinate dodecahedral structure.
In aqueous solution, vanadium(V) forms an extensive family of oxyanions as established by ⁵¹V NMR spectroscopy. The interrelationships in this family are described by the predominance diagram, which shows at least 11 species, depending on pH and concentration. The tetrahedral orthovanadate ion, VO³⁻
₄, is the principal species present at pH 12–14. Similar in size and charge to phosphorus(V), vanadium(V) also parallels its chemistry and crystallography. Orthovanadate VO³⁻
₄ is used in protein crystallography to study the biochemistry of phosphate. The tetrathiovanadate [VS₄]³⁻ is analogous to the orthovanadate ion.
At lower pH values, the monomer [HVO₄]²⁻ and dimer [V₂O₇]⁴⁻ are formed, with the monomer predominant at vanadium concentration of less than c. 10⁻²M (pV > 2, where pV is equal to the minus value of the logarithm of the total vanadium concentration/M). The formation of the divanadate ion is analogous to the formation of the dichromate ion. As the pH is reduced, further protonation and condensation to polyvanadates occur: at pH 4-6 [H₂VO₄]⁻ is predominant at pV greater than ca. 4, while at higher concentrations trimers and tetramers are formed. Between pH 2-4 decavanadate predominates, its formation from orthovanadate is represented by this condensation reaction:
10 [VO₄]³⁻ + 24 H⁺ → [V₁₀O₂₈]⁶⁻ + 12 H₂O
In decavanadate, each V(V) center is surrounded by six oxide ligands. Vanadic acid, H₃VO₄ exists only at very low concentrations because protonation of the tetrahedral species [H₂VO₄]⁻ results in the preferential formation of the octahedral [VO₂(H₂O)₄]⁺ species. In strongly acidic solutions, pH < 2, [VO₂(H₂O)₄]⁺ is the predominant species, while the oxide V₂O₅ precipitates from solution at high concentrations. The oxide is formally the acid anhydride of vanadic acid. The structures of many vanadate compounds have been determined by X-ray crystallography.
Vanadium(V) forms various peroxo complexes, most notably in the active site of the vanadium-containing bromoperoxidase enzymes. The species VO(O)₂(H₂O)₄⁺ is stable in acidic solutions. In alkaline solutions, species with 2, 3 and 4 peroxide groups are known; the last forms violet salts with the formula M₃V(O₂)₄ nH₂O (M= Li, Na, etc.), in which the vanadium has an 8-coordinate dodecahedral structure.
Vanadium