chlorovanadate

Chlorovanadate refers to a family of vanadium-containing compounds in which chloride ligands substitute for oxide ligands on a vanadate core. These species are found mainly as anions in salts or as charged oxo-chloro complexes in chloride-rich solutions. The exact composition and charge depend on the vanadium oxidation state (commonly +4 or +5) and the degree of chloride substitution, leading to a variety of stoichiometries such as tetra-chloro-oxo-vanadates and related mixed-ligand species.

In structural terms, chlorovanadates feature a vanadium center coordinated to oxide and chloride ligands. In many V(V) oxovanadates, the coordination around vanadium is described as octahedral, while in V(IV) chlorovanadates the geometry can be distorted due to the presence of multiple ligands and the d-electron configuration. Spectroscopic methods, including UV-Visible absorption, infrared spectroscopy, and, for V(IV), electron paramagnetic resonance, are commonly used to characterize these species.

Synthesis typically involves reacting vanadate sources (such as sodium or ammonium vanadate) with chloride sources (for example, hydrochloric acid or chloride salts) under controlled pH and concentration to favor chloride substitution. The resulting products can be isolated as salts with various cations or exist as solvated complexes in solution. The equilibrium among different chlorovanadate species is sensitive to pH, chloride concentration, and temperature.

Relevance and applications of chlorovanadates are mainly within inorganic synthesis and coordination chemistry, where they serve as models for mixed-ligand vanadium centers and as intermediates in studies of vanadium speciation in chloride-rich environments. They also appear in discussions of corrosion chemistry and materials science involving vanadium-chloride systems.

Safety: vanadium compounds can be toxic; appropriate handling, containment, and disposal procedures are essential. See also vanadate and vanadium oxychloride.