quality:corruption, structural:scholar_edition
Compounds and reactions

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 (Y O), 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 Y ion is colorless in solution because of the absence of electrons in the d and f electron shells.

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

With halogens, yttrium forms trihalides such as yttrium(III) fluoride (YF), yttrium(III) chloride (YCl), and yttrium(III) bromide (YBr) at temperatures above roughly 200 °C. Similarly, carbon, phosphorus, selenium, silicon and sulfur all form binary compounds with yttrium at elevated temperatures.

Organoyttrium chemistry is the study of compounds containing carbon–yttrium bonds. A few of these are known to have yttrium in the oxidation state 0. (The +2 state has been observed in chloride melts, and +1 in oxide clusters in the gas phase.) Some trimerization reactions were generated with organoyttrium compounds as catalysts. These syntheses use YCl as a starting material, obtained from Y O and 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 d -metal center through a η -hapticity. Vaporization of the graphite intercalation compounds graphite–Y or graphite– Y O leads to the formation of endohedral fullerenes such as Y@C. Electron spin resonance studies indicated the formation of Y and (C) ion pairs. The carbides Y C, Y C, and YC can be hydrolyzed to form hydrocarbons.