- Ruthenium (Ru) is a transition metal with atomic number 44, located in Group 8 of the periodic table alongside iron, osmium, and hassium.
- It is a hard, silvery-white metal with a bright metallic luster, excellent corrosion resistance, and high hardness.
- Ruthenium has eight valence electrons—two in the 5s subshell and six in the 4d subshell—and it commonly exhibits oxidation states ranging from 0 to +8, with +2, +3, and +4 being the most stable in its compounds. Its atomic structure consists of forty-four protons, typically fifty-four neutrons, and forty-four electrons arranged in five shells.
- Naturally occurring ruthenium comprises seven isotopes, with ruthenium-102 (¹⁰²Ru) being the most abundant (31.55%).
- Ruthenium is a rare element, with an average abundance in the Earth’s crust of approximately 0.001 parts per million. It occurs primarily in platinum ores and is often extracted as a byproduct of nickel and platinum mining. Major sources include Russia, South Africa, Canada, and the United States. The extraction process involves dissolving platinum ores in aqua regia, followed by chemical separation and precipitation of ruthenium compounds, which are subsequently reduced to the metallic form.
- The element was discovered in 1844 by Russian chemist Karl Ernst Claus, who isolated it from platinum ores found in the Ural Mountains. He named it “ruthenium” after Ruthenia, the Latin name for Russia. Metallic ruthenium was later obtained by reduction of ruthenium dioxide (RuO₂) with hydrogen at high temperatures.
- Ruthenium is highly valued in the electronics, chemical, and jewelry industries. It is used to harden platinum and palladium alloys, which are employed in electrical contacts, spark plugs, and jewelry. Ruthenium compounds also serve as catalysts in chemical reactions, particularly in ammonia synthesis, hydrogenation, and oxidation processes. In recent decades, ruthenium complexes have been investigated for applications in photochemistry, medicine, and solar energy conversion.
- Chemically, ruthenium exhibits a rich and versatile chemistry. It forms oxides, halides, sulfides, nitrides, and a wide variety of coordination compounds. Ruthenium tetroxide (RuO₄) is a strong oxidizing agent and is analogous to osmium tetroxide. Lower oxidation states, such as Ru(II) and Ru(III), form numerous stable complexes with nitrogen- and phosphorus-donor ligands, which have applications in catalysis and organometallic chemistry.
- Biologically, ruthenium has no known essential role in living organisms, but certain ruthenium complexes are being explored for anticancer therapies due to their ability to interact with DNA and proteins. The metal is generally considered to have low toxicity, although fine powders and volatile compounds can pose hazards if inhaled or ingested.
- From an environmental perspective, ruthenium is largely inert and poses minimal ecological risk. Mining and refining processes must be carefully managed to prevent heavy metal contamination, but ruthenium itself does not occur in large amounts in nature.
