Ruthenium

44

technetium ← Ruthenium → rhodium


Fe
↑
Ru
↓
Os




periodic table




General


Name, Symbol, Number

Ruthenium, Ru, 44


Chemical series
transition metals


Group, Period, Block

8, 5, d


Appearance
silvery white metallic 



Atomic mass
101.07(2) g/mol


Electron configuration
[Kr] 4d7 5s1


Electrons per shell
2, 8, 18, 15, 1


Physical properties


Density (near r.t.)
12.45 g/cm³


Liquid density at m.p.
10.65 g/cm³


Melting point
2607 K
(2334 °C, 4233 °F)


Boiling point
4423 K
(4150 °C, 7502 °F)


Heat of fusion
38.59 kJ/mol


Heat of vaporization
591.6 kJ/mol


Heat capacity
(25 °C) 24.06 J/(mol·K)




Vapor pressure


P/Pa
1
10
100
1 k
10 k
100 k


at T/K
2588
2811
3087
3424
3845
4388



Atomic properties


Crystal structure
hexagonal


Oxidation states
2, 3, 4, 6, 8
(mildly acidic oxide)


Electronegativity
2.2 (Pauling scale)


Ionization energies

1st: 710.2 kJ/mol


2nd: 1620 kJ/mol


3rd: 2747 kJ/mol


Atomic radius
130 pm


Atomic radius (calc.)
178 pm


Covalent radius
126 pm


Miscellaneous


Electrical resistivity
(0 °C) 71 nΩ·m


Thermal conductivity
(300 K) 117 W/(m·K)


Thermal expansion
(25 °C) 6.4 µm/(m·K)


Speed of sound (thin rod)
(20 °C) 5970 m/s


Speed of sound (thin rod)
(r.t.) 447 m/s


Shear modulus
173 GPa


Bulk modulus
220 GPa


Poisson ratio
0.30


Mohs hardness
6.5


Brinell hardness
2160 MPa


CAS registry number
7440-18-8


Notable isotopes




Main article: Isotopes of ruthenium


iso

NA

half-life

DM

DE (MeV)

DP


96Ru

5.52%

Ru is stable with 52 neutrons


97Ru

syn

2.9 d

ε

-

97Tc


γ

0.215, 0.324

-


98Ru

1.88%

Ru is stable with 54 neutrons


99Ru

12.7%

Ru is stable with 55 neutrons


100Ru

12.6%

Ru is stable with 56 neutrons


101Ru

17.0%

Ru is stable with 57 neutrons


102Ru

31.6%

Ru is stable with 58 neutrons


103Ru

syn

39.26 d

β-

0.226

103Rh


γ

0.497

-


104Ru

18.7%

Ru is stable with 60 neutrons


106Ru

syn

373.59 d

β-

0.039

106Rh


Ruthenium (chemical symbol Ru, atomic number 44) is a rare, hard, white metal. It is a member of the platinum group of elements and is found associated with platinum ores. Chemically, it is relatively inert.

Contents

1 Occurrence and isolation
2 History
3 Notable characteristics

3.1 Isotopes


4 Applications
5 Compounds

5.1 Organometallic compounds


6 Precautions
7 See also
8 References
9 External links
10 Credits



This element is a highly effective hardener and wear-resistant agent in alloys with platinum and other metals. Such alloys are used to make electrical contacts and fountain pen nibs. It is sometimes alloyed with gold in jewelry. In addition, ruthenium, its inorganic compounds, and organometallic complexes are versatile catalysts for diverse chemical reactions.

Occurrence and isolation
This element is generally found in ores with the other platinum group metals in the Ural Mountains of western Russia and in parts of North and South America. Small but commercially important quantities are also found in the mineral pentlandite (iron-nickel sulfide) extracted from Sudbury, Ontario (Canada), and in deposits of pyroxenite rock (containing silicate minerals) in South Africa.
This metal is commercially isolated through a complex chemical process in which hydrogen is used to reduce ammonium ruthenium chloride, yielding a powder. The powder is then consolidated by powder metallurgy techniques or by argon-arc welding.
It is also possible to extract ruthenium from spent nuclear fuel, which contains an average of two kilograms of ruthenium per metric ton. Ruthenium produced in such a way contains radioactive isotopes, some with a half-life of up to 373.59 days. Therefore this ruthenium has to be stored for at least ten years in a secured area to allow it to become stable.

History
Jöns Berzelius and Gottfried Osann nearly discovered ruthenium in 1827. They obtained crude platinum (from alluvial deposits in the Ural Mountains), treated it with aqua regia (a 3:1 mixture of concentrated hydrochloric acid and nitric acid), and examined the insoluble residues. Berzelius did not detect any unusual elements, but Osann thought he found three new metals and named them pluran, ruthen, and polin.
Later, in 1844, Karl Klaus demonstrated that Osann had obtained impure ruthenium oxide and went on to isolate the new element from platinum ore. For his work, Klaus is generally credited as the discoverer of ruthenium. Klaus named the element after Ruthenia, a latinized name for Russia, in recognition of the work of Osann and in honor of his own birthland—Klaus was born in Tartu, which was then a part of the Russian Empire.
It is also possible that Polish chemist Jedrzej Sniadecki isolated this element from platinum ores in 1807. He called it vestium. His work, however, was never confirmed and he later withdrew his discovery claim.

Notable characteristics
Ruthenium is classified as a transition metal. In the periodic table, it lies in period five just ahead of rhodium and palladium and is closely related to the latter two elements. In addition, it is situated in group eight (former group 8B), between iron and osmium.
A hard, white metal, ruthenium does not tarnish at normal temperatures, but under certain conditions it oxidizes explosively. It has four crystal modifications. It is a member of the platinum group and is relatively inert. It is not attacked by acids but dissolves in fused (molten) alkalis. Halogens can attack it at high temperatures. Small amounts of ruthenium can increase the hardness of platinum and palladium. Also, the corrosion resistance of titanium can be increased markedly by adding a small amount of ruthenium.
This metal can be plated by either electrodeposition or thermal decomposition methods. An alloy of ruthenium and molybdenum has been found to be superconductive at 10.6 K. The oxidation states of ruthenium range from +1 to +8, and -2 is known, but the most common oxidation states are +2, +3, and +4.

Isotopes
Seven stable isotopes of ruthenium have been found in nature: 96Ru, 98Ru, 99Ru, 100Ru, 101Ru, 102Ru, and 104Ru. Among the radioactive isotopes, the three with the longest half-lives are: 106Ru, with a half-life of 373.59 days; 103Ru, with a half-life of 39.26 days; and 97Ru, with a half-life of 2.9 days. Many other radioactive isotopes are known, with atomic mass numbers ranging from 87 to 120, but their half-lives are much shorter.

Applications
Ruthenium is a highly effective hardener in alloys with platinum and palladium, and such alloys are used to make electrical contacts that are resistant to severe wear.
It is sometimes alloyed with gold in jewelry.
0.1 percent ruthenium is added to titanium to improve its corrosion resistance a hundredfold.
For wear resistance, fountain pen nibs are often tipped with alloys containing ruthenium. For instance, from 1944 onward, the famous Parker 51 fountain pen was outfitted with the "RU" nib, a 14-carat gold nib tipped with 96.2% percent ruthenium, 3.8 percent iridium.
Ruthenium and its compounds are versatile catalysts. For instance, hydrogen sulfide (H2S) can be split by light in the presence of an aqueous suspension of cadmium sulfide (CdS) particles loaded with ruthenium dioxide. This may be a useful method of removing H2S from oil refining and other industrial processes.
Organometallic complexes of ruthenium (carbene and allenylidene complexes) have recently been found as highly efficient catalysts for certain chemical reactions (called olefin metathesis) that have important applications in organic and pharmaceutical chemistry.
Recently, large organometallic complexes of ruthenium have been found to exhibit anti-tumor activity, and a new group of anti-cancer medicines is now in the stage of clinical trials.
Ruthenium red, [(NH3)5Ru-O-Ru(NH3)4-O-Ru(NH3)5]6+, is a biological stain used to visualize polyanionic areas of membranes.
Some ruthenium complexes absorb light throughout the visible spectrum and are being actively studied for their potential in solar energy technologies.
Ruthenium may also be used in advanced, high-temperature, single-crystal superalloys, with applications that include the turbine blades of jet engines.
Compounds
Ruthenium(III) chloride or ruthenium trichloride (RuCl3): This compound can be found in the anhydrous and hydrated forms, both of which are dark brown or black solids. The name "ruthenium(III) chloride" more commonly refers to the hydrate, RuCl3•xH2O (where x may vary but usually equals three). The hydrate is a commonly used starting material for many hundreds of chemical compounds.
Ruthenium tetroxide (RuO4): This is a yellow, diamagnetic substance made up of molecules that are tetrahedral in shape. It is quite volatile, as expected for a small, electrically neutral, symmetrical oxide. It can oxidize virtually any hydrocarbon. It is used in organic syntheses to oxidize alkynes to 1,2-diketones and primary alcohols to carboxylic acids. RuO4 is highly toxic and readily explodes at slightly elevated temperatures. For this reason, most laboratories do not synthesize it directly but use an anionic derivative from a salt of "TPAP" [tetrapropylammonium perruthenate (Pr4N+ RuO4-)].
Organometallic compounds
Ruthenium readily forms organometallic compounds in which its atoms are directly bonded to carbon atoms. These compounds tend to be darker in color and react more quickly than osmium compounds.
The ruthenium organometallic compound easiest to make is RuHCl(CO)(PPh3)3. This compound has two forms (yellow and pink) that are identical when in solution but different in the solid state.
Grubbs' catalyst and Roper's complex are two of the important organometallic catalysts based on ruthenium. Another organometallic compound, called bis(2,4-dimethylpentadienyl)ruthenium, can be readily synthesized at high yields and can be used for the vapor-phase deposition of metallic ruthenium and to catalyze chemical reactions.

Precautions
Ruthenium plays no known biological role but it strongly stains human skin. It may be carcinogenic and may bioaccumulate in bone. The compound ruthenium tetroxide (RuO4), similar to osmium tetroxide, is highly toxic and may explode.

See also
Chemical element
Metal
Palladium
Periodic table
Rhodium
Transition metal
ReferencesISBN links support NWE through referral fees
Canterford, J.H., and R. Colton. 1968. Halides of the Second and Third Row Transition Metals. London: Wiley-Interscience.
Chang, Raymond. Chemistry, 9th ed. New York: McGraw-Hill Science/Engineering/Math, 2006. ISBN 0073221031
Cotton, F. Albert and Wilkinson, Geoffrey. 1980. Advanced Inorganic Chemistry, 4th ed. New York: Wiley. ISBN 0-471-02775-8
Cotton, S.A. 1997. Chemistry of the Precious Metals. Chapman & Hall. ISBN 0-7514-0413-6
Greenwood, N.N. and Earnshaw, A. 1998. Chemistry of the Elements, 2nd Edition. Oxford, U.K.; Burlington, Massachusetts: Butterworth-Heinemann, Elsevier Science. ISBN 0750633654
Ruthenium Los Alamos National Laboratory. Retrieved December 7, 2007.
External links
All links retrieved December 22, 2022.

WebElements.com – Ruthenium

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