Ruthenium
Overview
 
Ruthenium is a chemical element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...

 with symbol Ru and atomic number
Atomic number
In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...

 44. It is a rare transition metal
Transition metal
The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...

 belonging to the platinum group
Platinum group
The platinum group metals is a term used sometimes to collectively refer to six metallic elements clustered together in the periodic table.These elements are all transition metals, lying in the d-block .The six...

 of the periodic table
Periodic table
The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus...

. Like the other metals of the platinum group, ruthenium is inert to most chemicals. The Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n scientist Karl Ernst Claus discovered the element in 1844 and named it after Ruthenia
Ruthenia
Ruthenia is the Latin word used onwards from the 13th century, describing lands of the Ancient Rus in European manuscripts. Its geographic and culturo-ethnic name at that time was applied to the parts of Eastern Europe. Essentially, the word is a false Latin rendering of the ancient place name Rus...

, the Latin word for Rus'. Ruthenium usually occurs as a minor component of platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...

 ores and its annual production is only about 12 tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...

s worldwide.
Encyclopedia
Ruthenium is a chemical element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...

 with symbol Ru and atomic number
Atomic number
In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...

 44. It is a rare transition metal
Transition metal
The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...

 belonging to the platinum group
Platinum group
The platinum group metals is a term used sometimes to collectively refer to six metallic elements clustered together in the periodic table.These elements are all transition metals, lying in the d-block .The six...

 of the periodic table
Periodic table
The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus...

. Like the other metals of the platinum group, ruthenium is inert to most chemicals. The Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n scientist Karl Ernst Claus discovered the element in 1844 and named it after Ruthenia
Ruthenia
Ruthenia is the Latin word used onwards from the 13th century, describing lands of the Ancient Rus in European manuscripts. Its geographic and culturo-ethnic name at that time was applied to the parts of Eastern Europe. Essentially, the word is a false Latin rendering of the ancient place name Rus...

, the Latin word for Rus'. Ruthenium usually occurs as a minor component of platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...

 ores and its annual production is only about 12 tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...

s worldwide. Most ruthenium is used for wear-resistant electrical contacts and the production of thick-film resistors. A minor application of ruthenium is its use in some platinum alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

s.

Physical properties

A polyvalent hard white metal, ruthenium is a member of the platinum group
Platinum group
The platinum group metals is a term used sometimes to collectively refer to six metallic elements clustered together in the periodic table.These elements are all transition metals, lying in the d-block .The six...

 and is in group 8
Group 8 element
A Group 8 element is one in the series of elements in group 8 in the periodic table, which consists of the transition metals iron , ruthenium , osmium and hassium ....

 of the periodic table:
Z
Atomic number
In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...

 
Element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...

 
No. of electrons/shell
Electron shell
An electron shell may be thought of as an orbit followed by electrons around an atom's nucleus. The closest shell to the nucleus is called the "1 shell" , followed by the "2 shell" , then the "3 shell" , and so on further and further from the nucleus. The shell letters K,L,M,.....

26 iron 2, 8, 14, 2
44 ruthenium 2, 8, 18, 15, 1
76 osmium 2, 8, 18, 32, 14, 2
108 hassium 2, 8, 18, 32, 32, 14, 2


However, it has an atypical configuration in its outermost electron shells: whereas all other group 8 elements have 2 electrons in the outermost shell, in ruthenium, one of those is transferred to a lower shell. This effect can be observed in the neighboring metals niobium
Niobium
Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...

 (41), rhodium
Rhodium
Rhodium is a chemical element that is a rare, silvery-white, hard and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope, 103Rh. Naturally occurring rhodium is found as the free metal, alloyed...

 (45), and palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...

 (46).

Ruthenium has four crystal modifications and does not tarnish at normal temperatures. Ruthenium dissolves in fused alkalis, is not attacked by acids but is attacked by halogen
Halogen
The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style of the periodic table, comprising fluorine , chlorine , bromine , iodine , and astatine...

s at high temperatures. Small amounts of ruthenium can increase the hardness of platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...

 and palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...

. The corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...

 resistance of titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

 is increased markedly by the addition of a small amount of ruthenium.

This metal can be plated either by electroplating
Electroplating
Electroplating is a plating process in which metal ions in a solution are moved by an electric field to coat an electrode. The process uses electrical current to reduce cations of a desired material from a solution and coat a conductive object with a thin layer of the material, such as a metal...

 or by thermal decomposition methods. A ruthenium-molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...

 alloy is known to be superconductive
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum...

 at temperatures below 10.6 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

.

Isotopes

Naturally occurring ruthenium is composed of seven stable isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

s. Additionally, 34 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are 106Ru with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...

 of 373.59 days, 103Ru with a half-life of 39.26 days and 97Ru with a half-life of 2.9 days.

Fifteen other radioisotopes have been characterized with atomic weight
Atomic weight
Atomic weight is a dimensionless physical quantity, the ratio of the average mass of atoms of an element to 1/12 of the mass of an atom of carbon-12...

s ranging from 89.93 u (90Ru) to 114.928 u (115Ru). Most of these have half-lives that are less than five minutes except 95Ru (half-life: 1.643 hours) and 105Ru (half-life: 4.44 hours).

The primary decay mode before the most abundant isotope, 102Ru, is electron capture
Electron capture
Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino...

 and the primary mode after is beta emission. The primary decay product
Decay product
In nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps...

 before 102Ru is technetium
Technetium
Technetium is the chemical element with atomic number 43 and symbol Tc. It is the lowest atomic number element without any stable isotopes; every form of it is radioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature...

 and the primary mode after is rhodium
Rhodium
Rhodium is a chemical element that is a rare, silvery-white, hard and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope, 103Rh. Naturally occurring rhodium is found as the free metal, alloyed...

.

Occurrence

Ruthenium is exceedingly rare and is the 74th most abundant metal on Earth
Abundance of elements in Earth's crust
The table shows the abundance of elements in Earth's crust. Numbers show percentage or parts per million in mass; 10,000 ppm = 1%.Note that numbers are estimates, and they will vary depending on source and method of estimation. Order of magnitude of data can roughly be relied upon.The table shows...

. This element is generally found in ores with the other platinum group metals in the Ural Mountains
Ural Mountains
The Ural Mountains , or simply the Urals, are a mountain range that runs approximately from north to south through western Russia, from the coast of the Arctic Ocean to the Ural River and northwestern Kazakhstan. Their eastern side is usually considered the natural boundary between Europe and Asia...

 and in North and South America. Small but commercially important quantities are also found in pentlandite
Pentlandite
Pentlandite is an iron-nickel sulfide, 9S8. Pentlandite usually has a Ni:Fe ratio of close to 1:1. It also contains minor cobalt.Pentlandite forms isometric crystals, but is normally found in massive granular aggregates. It is brittle with a hardness of 3.5 - 4 and specific gravity of 4.6 - 5.0 and...

 extracted from Sudbury, Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, and in pyroxenite
Pyroxenite
Pyroxenite is an ultramafic igneous rock consisting essentially of minerals of the pyroxene group, such as augite and diopside, hypersthene, bronzite or enstatite. They are classified into clinopyroxenites, orthopyroxenites, and the websterites which contain both pyroxenes...

 deposits in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

. The native form of ruthenium is a very rare mineral (Ir replaces part of Ru in its structure).

Mining

Roughly 12 tonnes of Ru is mined each year with world reserves estimated as 5,000 tonnes. The composition of the mined platinum group metal (PGM) mixtures varies in a wide range depending on the geochemical formation. For example, the PGMs mined in South Africa contain on average 11% ruthenium while the PGMs mined in the former USSR contain only 2% based on research dating from 1992.

Ruthenium, like the other platinum group metals, is obtained commercially as a by-product from nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

 and copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 mining and processing as well as by the processing of platinum group metal ores. During electrorefining of copper and nickel, noble metals such as silver, gold and the platinum group metals including selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...

 and tellurium settle to the bottom of the cell as anode mud, which forms the starting point for their extraction. In order to separate the metals, they must first be brought into solution. Several methods are available depending on the separation process and the composition of the mixture; two representative methods are fusion with sodium peroxide
Sodium peroxide
Sodium peroxide is the inorganic compound with the formula Na2O2. This solid is the product when sodium is burned with oxygen. It is a strong base and a potent oxidizing agent. It exists in several hydrates and peroxyhydrates including Na2O2·2H2O2·4H2O, Na2O2·2H2O, Na2O2·2H2O2, and...

 followed by dissolution in aqua regia
Aqua regia
Aqua regia or aqua regis is a highly corrosive mixture of acids, fuming yellow or red solution, also called nitro-hydrochloric acid. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid, usually in a volume ratio of 1:3, respectively...

, and dissolution in a mixture of chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 with hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

. Osmium, ruthenium, rhodium and iridium can be separated from platinum and gold and base metals by their insolubility in aqua regia, leaving a solid residue. Rhodium can be separated from the residue by treatment with molten sodium bisulfate. The insoluble residue, containing Ru, Os and Ir is treated with sodium oxide, in which Ir is insoluble, producing water-soluble Ru and Os salts. After oxidation to the volatile oxides, is separated from by precipitation of (NH4)3RuCl6 with ammonium chloride or by distillation or extraction with organic solvents of the volatile osmium tetroxide. Hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 is used to reduce ammonium
Ammonium
The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...

 ruthenium chloride yielding a powder. The first method to precipitate the ruthenium with ammonium chloride is similar to the procedure that Smithson Tennant
Smithson Tennant
Smithson Tennant FRS was an English chemist.Tennant is best known for his discovery of the elements iridium and osmium, which he found in the residues from the solution of platinum ores in 1803. He also contributed to the proof of the identity of diamond and charcoal. The mineral tennantite is...

 and William Hyde Wollaston
William Hyde Wollaston
William Hyde Wollaston FRS was an English chemist and physicist who is famous for discovering two chemical elements and for developing a way to process platinum ore.-Biography:...

 used for their separation. Several methods are suitable for industrial scale production. In either case, the product is reduced using hydrogen, yielding the metal as a powder or sponge that can be treated using powder metallurgy
Powder metallurgy
Powder metallurgy is the process of blending fine powdered materials, pressing them into a desired shape , and then heating the compressed material in a controlled atmosphere to bond the material . The powder metallurgy process generally consists of four basic steps: powder manufacture, powder...

 techniques or by argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...

-arc welding
Arc welding
Arc welding is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct or alternating current, and consumable or non-consumable electrodes...

.

From used nuclear fuels

Ruthenium is a fission product of uranium-235
Uranium-235
- References :* .* DOE Fundamentals handbook: Nuclear Physics and Reactor theory , .* A piece of U-235 the size of a grain of rice can produce energy equal to that contained in three tons of coal or fourteen barrels of oil. -External links:* * * one of the earliest articles on U-235 for the...

. Each kilo of fission products contains significant amounts of the lighter platinum group metals and also ruthenium. Used nuclear fuel might be a possible source for ruthenium. The complicated extraction is expensive and the also present radioactive isotopes of ruthenium would make a storage for several half-lives of the decaying isotopes necessary. This makes this source of ruthenium unattractive and no large-scale extraction has been started.

Chemical compounds

The oxidation state
Oxidation state
In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...

s of ruthenium range from 0 to +8, and −2. The properties of ruthenium and osmium compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

s are often similar. The +2, +3, and +4 states are the most common. The most prevalent precursor is ruthenium trichloride, a red solid that is poorly defined chemically but versatile synthetically.

Oxides

Ru can oxidize to ruthenium tetroxide
Ruthenium tetroxide
Ruthenium tetroxide is a diamagnetic tetrahedral ruthenium compound. As expected for a charge-neutral symmetrical oxide, it is quite volatile. The analogous OsO4 is more widely used and better known...

, RuO4, a strong oxidizing agent with structure analogous to osmium tetroxide. Other examples are ruthenium(IV) oxide
Ruthenium(IV) oxide
Ruthenium oxide is a black chemical compound containing the rare metal ruthenium and oxygen. The most often used O2 catalyst is ruthenium oxide; however, care must be taken since hydrates of this oxide exist....

 (RuO2, oxidation state +4), dipotassium ruthenate (K2RuO4, +6), and potassium perruthenate (KRuO4, +7).

Coordination and organometallic complexes

Ruthenium forms a variety of coordination complexes. Examples are the many pentammine derivatives [Ru(NH3)5L]n+ which often exist in both Ru(II) and Ru(III). Derivatives of bipyridine
Bipyridine
Bipyridines are a family of chemical compounds with the formula 2, which are formed by the coupling of two pyridine rings. Six isomers of bipyridine exist, but two isomers are prominent: 2,2'-bipyridine is a popular ligand in coordination chemistry and 4,4'-bipyridine is a precursor to the...

 and terpyridine
Terpyridine
Terpyridine is a heterocyclic compound derived from pyridine. This colourless solid is used as a ligand in coordination chemistry.-Synthesis:...

 are numerous, best known being the luminiscent tris(bipyridine)ruthenium(II) chloride
Tris(bipyridine)ruthenium(II) chloride
Trisruthenium dichloride is the coordination compound with the formula [Ru3]Cl2. This red crystalline salt is obtained as the hexahydrate, although all of the properties of interest are in the cation [Ru3]2+, which has received much attention because of its distinctive optical properties...

.

Ruthenium form a wide range compounds with carbon-ruthenium bonds. Ruthenocene
Ruthenocene
Ruthenocene is an organoruthenium compound with the formula 2Ru. This pale yellow, volatile solid is classified as a sandwich compound and more specifically, as a metallocene.-Structure and bonding:...

 is analogous to ferrocene structurally, but exhibits distinctive redox properties. A large number of complexes of carbon monoxide are known, the parent being triruthenium dodecacarbonyl
Triruthenium dodecacarbonyl
Triruthenium dodecacarbonyl is the chemical compound with the formula Ru312. This orange-colored metal carbonyl cluster is a precursor to other organoruthenium compounds.-Structure and synthesis:...

. The analogue of iron pentacarbonyl
Iron pentacarbonyl
Iron pentacarbonyl, also known as iron carbonyl, is the compound with formula 5. Under standard conditions Fe5 is a free-flowing, straw-colored liquid with a pungent odour. This compound is a common precursor to diverse iron compounds, including many that are useful in organic synthesis. Fe5 is...

, ruthenium pentacarbonyl is unstable at ambient conditions. Ruthenium trichloride
Ruthenium(III) chloride
Ruthenium chloride is the chemical compound with the formula RuCl3. "Ruthenium chloride" more commonly refers to the hydrate RuCl3·xH2O. Both the anhydrous and hydrated species are dark brown or black solids...

 carbonylates
Carbonylation
Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry.-Organic chemistry:...

 (reacts with carbon monoxide) to give mono- and diruthenium(II) carbonyls from which many derivatives have been prepared such as RuHCl(CO)(PPh3)3 and Ru(CO)2(PPh3)3 (Roper's complex). Heating solutions of ruthenium trichloride in alcohols with triphenylphosphine
Triphenylphosphine
Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature...

 gives tris(triphenylphosphine)ruthenium dichloride (RuCl2(PPh3)3), which converts to the hydride complex chlorohydridotris(triphenylphosphine)ruthenium(II) (RuHCl(PPh3)3).

In the area of fine chemical synthesis, Grubbs' catalyst
Grubbs' catalyst
Grubbs' Catalyst is a transition metal carbene complex named after Robert H. Grubbs, the chemist who first synthesized it. There are two generations of the catalyst, as shown on the right. In contrast to other olefin metathesis catalysts, Grubbs' Catalysts tolerate other functional groups in the...

 is used for alkene metathesis.

Ruthenides

Metal Ruthenides (Ru2-) are very rare, but are commonly found in superconductor applications, especially with regard to lanthanide metals e.g. cerium
Cerium
Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet . Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight...

 ruthenide (CeRu2).

History

Though naturally occurring platinum, containing all six platinum group metals, was used for a long time by pre-Columbian
Pre-Columbian
The pre-Columbian era incorporates all period subdivisions in the history and prehistory of the Americas before the appearance of significant European influences on the American continents, spanning the time of the original settlement in the Upper Paleolithic period to European colonization during...

 Americans and known as a material to European chemists from the mid-16th century, it took until the mid-18th century for platinum to be identified as a pure element. The discovery that natural platinum contained palladium, rhodium, osmium and iridium took place in the first decade of the 19th century. Platinum in alluvial sands
Alluvium
Alluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...

 of Russian rivers gave access to raw material for use in plates and medals and for the minting of ruble
Ruble
The ruble or rouble is a unit of currency. Currently, the currency units of Belarus, Russia, Abkhazia, South Ossetia and Transnistria, and, in the past, the currency units of several other countries, notably countries influenced by Russia and the Soviet Union, are named rubles, though they all are...

 coins
COinS
ContextObjects in Spans, commonly abbreviated COinS, is a method to embed bibliographic metadata in the HTML code of web pages. This allows bibliographic software to publish machine-readable bibliographic items and client reference management software to retrieve bibliographic metadata. The...

, starting in 1828. Residues of platinum production for minting were available in the Russian Empire, and therefore most of the research on them was done in Eastern Europe.

It is possible that the Polish
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

 chemist Jędrzej Śniadecki
Jedrzej Sniadecki
Jędrzej Śniadecki was a Polish writer, physician, chemist and biologist. His achievements include the creation of modern Polish terminology in the field of chemistry.-Life and work:...

 isolated element 44 (which he called "vestium") from platinum ores in 1807. He published his discovery in Polish language in article "Rosprawa o nowym metallu w surowey platynie odkrytym" in 1808. His work was never confirmed, however, and he later withdrew his claim of discovery. Jöns Berzelius and Gottfried Osann
Gottfried Osann
Gottfried Wilhelm Osann was a German chemist and physicist. He is known for his work on the chemistry of platinum metals....

 nearly discovered ruthenium in 1827. They examined residues that were left after dissolving crude platinum from the Ural Mountains
Ural Mountains
The Ural Mountains , or simply the Urals, are a mountain range that runs approximately from north to south through western Russia, from the coast of the Arctic Ocean to the Ural River and northwestern Kazakhstan. Their eastern side is usually considered the natural boundary between Europe and Asia...

 in aqua regia
Aqua regia
Aqua regia or aqua regis is a highly corrosive mixture of acids, fuming yellow or red solution, also called nitro-hydrochloric acid. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid, usually in a volume ratio of 1:3, respectively...

. Berzelius did not find any unusual metals, but Osann thought he found three new metals, pluranium, ruthenium and polinium. This discrepancy led to a long-standing controversy between Berzelius and Osann about the composition of the residues.

In 1844, the Russian scientist Karl Klaus showed that the compounds prepared by Gottfried Osann contained small amounts of ruthenium, which Klaus had discovered the same year. Klaus isolated ruthenium from the platinum residues of the rouble production while he was working in Kazan University, Kazan
Kazan
Kazan is the capital and largest city of the Republic of Tatarstan, Russia. With a population of 1,143,546 , it is the eighth most populous city in Russia. Kazan lies at the confluence of the Volga and Kazanka Rivers in European Russia. In April 2009, the Russian Patent Office granted Kazan the...

. Klaus showed that ruthenium oxide contained a new metal and obtained 6 grams of ruthenium from the part of crude platinum that is insoluble in aqua regia
Aqua regia
Aqua regia or aqua regis is a highly corrosive mixture of acids, fuming yellow or red solution, also called nitro-hydrochloric acid. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid, usually in a volume ratio of 1:3, respectively...

.

The name derives from Ruthenia
Ruthenia
Ruthenia is the Latin word used onwards from the 13th century, describing lands of the Ancient Rus in European manuscripts. Its geographic and culturo-ethnic name at that time was applied to the parts of Eastern Europe. Essentially, the word is a false Latin rendering of the ancient place name Rus...

, the Latin word for Rus', a historical area which includes present-day western Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, Ukraine
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

, Belarus
Belarus
Belarus , officially the Republic of Belarus, is a landlocked country in Eastern Europe, bordered clockwise by Russia to the northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Its capital is Minsk; other major cities include Brest, Grodno , Gomel ,...

, and parts of Slovakia
Slovakia
The Slovak Republic is a landlocked state in Central Europe. It has a population of over five million and an area of about . Slovakia is bordered by the Czech Republic and Austria to the west, Poland to the north, Ukraine to the east and Hungary to the south...

 and Poland
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

. Karl Klaus used the name proposed by Gottfried Osann
Gottfried Osann
Gottfried Wilhelm Osann was a German chemist and physicist. He is known for his work on the chemistry of platinum metals....

 in 1828. He chose the element's name in honor of his birthland, as he was born in Tartu
Tartu
Tartu is the second largest city of Estonia. In contrast to Estonia's political and financial capital Tallinn, Tartu is often considered the intellectual and cultural hub, especially since it is home to Estonia's oldest and most renowned university. Situated 186 km southeast of Tallinn, the...

, Estonia
Estonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...

, which was at the time a part of the Russian Empire
Russian Empire
The Russian Empire was a state that existed from 1721 until the Russian Revolution of 1917. It was the successor to the Tsardom of Russia and the predecessor of the Soviet Union...

.

Applications

Because of its ability to harden platinum and palladium, ruthenium is used in platinum and palladium alloys to make wear-resistant electrical contacts. In this application, only thin plated films are used to achieve the necessary wear-resistance. Because of its lower cost and similar properties compared to rhodium, the use as plating material for electric contacts is one of the major applications. The thin coatings are either put on by electroplating or sputtering.

Ruthenium dioxide and lead and bismuth ruthenates are used in thick film chip resistors. These two electronic applications account for 50% of the ruthenium consumption.

There are only a few alloys used other than with elements of the platinum group metals. Ruthenium is always used in small quantities in those alloys to improve certain properties of the alloys. One example is the use of small amounts of ruthenium to increase the stability of gold in jewelry. The beneficial effect on the corrosion resistance of titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

 alloys led to the development of a special alloy containing 0.1% ruthenium . Ruthenium is also used in some advanced high-temperature single-crystal superalloys, with applications including the turbine blades in jet engines. Several nickel based superalloy compositions are described in the literature. Among them are EPM-102 (with 3 % Ru) and TMS-162 (with 6 % Ru), both containing 6 % rhenium
Rhenium
Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. With an average concentration of 1 part per billion , rhenium is one of the rarest elements in the Earth's crust. The free element has...

, as well as TMS-138 and TMS-174. Fountain pen
Fountain pen
A fountain pen is a nib pen that, unlike its predecessor the dip pen, contains an internal reservoir of water-based liquid ink. The pen draws ink from the reservoir through a feed to the nib and deposits it on paper via a combination of gravity and capillary action...

 nibs are frequently tipped with alloys containing ruthenium. From 1944 onward, the famous Parker 51
Parker 51
The Parker 51, introduced in 1941, is a famous fountain pen. Parker’s period advertising called it “The World’s Most Wanted Pen,” and this assertion was true although a little deceptive; the U.S.A. entered World War II in December 1941, and the War Production Board placed severe restrictions on...

 fountain pen was fitted with the "RU" nib, a 14K gold nib tipped with 96.2% ruthenium and 3.8% iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...

.

Ruthenium is a component of mixed-metal oxide (MMO) anodes used for cathodic protection of underground and submerged structures, and for electrolytic cells for chemical processes such as generating chlorine
Chlorine production
This article presents the industrial and laboratory methodologies to prepare elemental chlorine.- Gas extraction :Chlorine can be manufactured by electrolysis of a sodium chloride solution . The production of chlorine results in the co-products caustic soda and hydrogen gas . These two products,...

 from salt water. The fluorescence
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...

 of some ruthenium complexes is quenched by oxygen, which has led to their use as optode
Optode
An optode or optrode is an optical sensor device that optically measures a specific substance usually with the aid of a chemical transducer.-Construction:...

 sensors for oxygen. Ruthenium red
Ruthenium red
The inorganic dye ammoniated ruthenium oxychloride, also known as Ruthenium Red, is used in histology to stain aldehyde fixed mucopolysaccharides....

, [(NH3)5Ru-O-Ru(NH3)4-O-Ru(NH3)5]6+, is a biological stain used to stain polyanionic molecules such as pectin
Pectin
Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. It was first isolated and described in 1825 by Henri Braconnot...

 and nucleic acids for light microscopy and electron microscopy. The beta-decaying isotope 106 of ruthenium is used in radiotherapy of eye tumors, mainly malignant melanomas of the uvea
Uvea
The uvea , also called the uveal layer, uveal coat, uveal tract, or vascular tunic, is the pigmented middle of the three concentric layers that make up an eye. The name is possibly a reference to its reddish-blue or almost black colour, wrinkled appearance and grape-like size and shape when...

. Ruthenium-centered complexes are being researched for possible anticancer properties. Ruthenium, unlike traditional platinum complexes, shows greater resistance to hydrolysis and more selective action on tumors. NAMI-A
NAMI-A
NAMI-A and KP1019 are two ruthenium anticancer agents that have already entered clinical trials. They belong to the RAPTA series of complexes that have shown potential for the further development of anticancer drugs. NAMI is the acronym for New Anti-tumour Metastasis Inhibitor; -A means that this...

 and KP1019 are two drugs undergoing clinical evaluation against metastatic tumors and colon cancers.

Catalysis

Ruthenium is a versatile catalyst. Hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

 can be split by light by using an aqueous suspension of CdS
Cadmium sulfide
Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow solid. It occurs in nature with two different crystal structures as the rare minerals greenockite and hawleyite, but is more prevalent as an impurity substituent in the similarly structured zinc ores...

 particles loaded with ruthenium dioxide. This may be useful in the removal of H
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

2S
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 in oil refineries
Oil refinery
An oil refinery or petroleum refinery is an industrial process plant where crude oil is processed and refined into more useful petroleum products, such as gasoline, diesel fuel, asphalt base, heating oil, kerosene, and liquefied petroleum gas...

 and other industrial processing facilities. Organometallic ruthenium carbene
Carbene
In chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is RR'C:, but the carbon can instead be double-bonded to one group. The term "carbene" may also merely refer to the compound H2C:, also called...

 and alkylidene complexes have been found to be highly efficient catalysts for olefin metathesis
Olefin metathesis
Olefin metathesis or transalkylidenation is an organic reaction that entails redistribution of alkylene fragments by the scission of carbon - carbon double bonds in olefins . Its advantages include the creation of fewer sideproducts and hazardous wastes. Yves Chauvin, Robert H. Grubbs, and Richard R...

, a process with important applications in organic and pharmaceutical chemistry.

Solar energy conversion

Some ruthenium complexes absorb light
Absorption (electromagnetic radiation)
In physics, absorption of electromagnetic radiation is the way by which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the electromagnetic energy is transformed to other forms of energy for example, to heat. The absorption of light during wave propagation is...

 throughout the visible spectrum and are being actively researched in various, potential, solar energy technologies. For example, Ruthenium-based compounds have been used for light absorption in dye-sensitized solar cells, a promising new low-cost solar cell system.

Data storage

Chemical vapor deposition of ruthenium
Chemical vapor deposition of ruthenium
Chemical vapor deposition of ruthenium is a method to deposit thin layers of ruthenium on substrate by Chemical vapor deposition .A unique challenge arises in trying to grow impurity-free films of a catalyst in Chemical vapor deposition . Ruthenium metal activates C-H and C-C bonds, that aids C-H...

 (CVD) is used as a method to produce thin films of pure ruthenium on substrates. These films show promising properties for the use in microchips and for the giant magnetoresistive read element for hard disk drives. Ruthenium was also suggested as a possible material for microelectronics because its use is compatible with semiconductor processing techniques.

Exotic materials

Many ruthenium based oxides show very unusual properties, such as a Quantum Critical Point
Quantum Critical Point
A quantum critical point is a special class of continuous phase transition that takes place at the absolute zero of temperature, typically in a material where the phase transition temperature has been driven to zero by the application of a pressure, field or through doping.Conventional phase...

 behavior, exotic superconductivity
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum...

, and high temperature ferromagnetism
Ferromagnetism
Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished...

.

External links

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