Yttrium(III) Ion

As a trivalent transition metal, yttrium forms various inorganic compounds, generally in the oxidation state of +3, by giving up all three of its valence electrons. A good example is yttrium(III) oxide (Y2O3), also known as yttria, a six-coordinate white solid.

Yttrium forms a water-insoluble fluoride, hydroxide, and oxalate, but its bromide, chloride, iodide, nitrate and sulfate are all soluble in water. The Y3+ ion is colorless in solution because of the absence of electrons in the d and f electron shells. With halogens, yttrium forms trihalides such as yttrium(III) fluoride (YF3), yttrium(III) chloride (YCl3), and yttrium(III) bromide (YBr3) at temperatures above roughly 200 °C.

Similarly, carbon, phosphorus, selenium, silicon and sulfur all form binary compounds with yttrium at elevated temperatures.

Water readily reacts with yttrium and its compounds to form Y₂O₃ . Concentrated nitric and hydrofluoric acids do not rapidly attack yttrium, but other strong acids do.

Organoyttrium chemistry is the study of compounds containing carbon-yttrium bonds. They are studied in academic research, but have not received widespread use otherwise. These compounds use YCl₃ as a starting material, which is in turn obtained in a reaction of Y₂O₃ with concentrated hydrochloric acid and ammonium chloride.

Hapticity is a term to describe the coordination of a group of contiguous atoms of a ligand bound to the central atom; it is indicated by the Greek character eta, η . Yttrium complexes were the first examples of complexes where carboranyl ligands were bound to a d0-metal center through a η7-hapticity. Vaporization of the graphite intercalation compounds graphite–Y or graphite–Y2O3 leads to the formation of endohedral fullerenes such as Y@C82. Electron spin resonance studies indicated the formation of Y³⁺ and (C₈₂)³⁻ ion pairs. The carbides Y3C, Y2C, and YC2 can be hydrolyzed to form hydrocarbons.