titanyl

Titanyl is a term used in inorganic chemistry to denote the oxido-titanium moiety, typically described as the dioxo titanium(IV) fragment TiO2^2+. In many compounds this unit is viewed as a titanyl group and is best known for the linear TiO2 core with two oxo ligands, O=Ti=O.

The titanium center in titanyl species is in the +4 oxidation state. The titanyl unit can be six-coordinate, with two additional ligands occupying the remaining coordination sites, giving a distorted octahedral environment that depends on the surrounding ligands. The Ti–O bonds are strong, and the O=Ti=O core can influence both the geometry and reactivity of the complex.

Titanyl species form by hydrolysis or oxidation of titanium(IV) salts in aqueous or nonaqueous media and appear as intermediates or building blocks in a variety of titanium-containing salts and complexes. They are common in oxometalate chemistry and in solid-state contexts as surface or structural motifs related to titanium oxide materials.

Spectroscopic and reactive features of titanyl groups include a characteristic Ti=O stretching vibration in infrared spectra and distinct ligand-to-metal charge-transfer bands in the UV–visible region. The Ti=O bonds confer strong oxophilicity, enabling the formation of adducts with oxygen- or nitrogen-donor ligands and enabling further condensation toward larger titanium-oxide architectures.

Titanyl motifs are central to the chemistry of titanium in coordination chemistry and materials science, serving as building blocks for catalysts, precursor compounds for titanium dioxide production, and related coatings and photocatalytic materials.