Ruthenium on alumina

Application

When heated in air at 500 to 700°C, ruthenium converts to its dioxide, RuO2, a black crystalline solid of rutile structure. A trioxide of ruthenium, RuO3, also is known; formed when the metal is heated above 1,000°C. Above 1,100°C the metal loses weight because trioxide partially volatilizes. Ruthenium also forms a tetroxide, RuO4, which, unlike osmium, is not produced by direct union of the elements.

Halogens react with the metal at elevated temperatures. Fluorine reacts with ruthenium at 300°C forming colorless vapors of pentafluoride, RuF5, which at ordinary temperatures converts to a green solid. Chlorine combines with the metal at 450°C to form black trichloride, RuCl3, which is insoluble in water. Ru metal at ambient temperature is attacked by chlorine water, bromine water, or alcoholic solution of iodine.

Ruthenium is stable in practically all acids including aqua regia. Fusion with an alkali in the presence of an oxidizing agent forms ruthenate, RuO42- and perruthenate, RuO4¯.

When finely-divided Ru metal is heated with carbon monoxide under 200 atm pressure, ruthenium converts to pentacarbonyl, Ru(CO)5, a colorless liquid that decomposes on heating to diruthenium nonacarbonyl, Ru2(CO)9, a yellow crystalline solid. Ruthenium reacts with cyclopentadiene in ether to form a sandwich complex, a yellow crystalline compound, bis(cyclopentadiene) ruthenium(0), also known as ruthenocene.