Last updated

Rhodium, 45Rh
Rhodium powder pressed melted.jpg
Pronunciation /ˈrdiəm/ (ROH-dee-əm)
Appearancesilvery white metallic
Standard atomic weight Ar°(Rh)
Rhodium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


Atomic number (Z)45
Group group 9
Period period 5
Block   d-block
Electron configuration [ Kr ] 4d8 5s1
Electrons per shell2, 8, 18, 16, 1
Physical properties
Phase at  STP solid
Melting point 2237  K (1964 °C,3567 °F)
Boiling point 3968 K(3695 °C,6683 °F)
Density (at 20° C)12.423 g/cm3 [3]
when liquid (at m.p.)10.7 g/cm3
Heat of fusion 26.59  kJ/mol
Heat of vaporization 493 kJ/mol
Molar heat capacity 24.98 J/(mol·K)
Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)228824962749306334053997
Atomic properties
Oxidation states −3 [4] , −1, 0, +1, +2, +3, +4, +5, +6, +7 [5] (an  amphoteric oxide)
Electronegativity Pauling scale: 2.28
Ionization energies
  • 1st: 719.7 kJ/mol
  • 2nd: 1740 kJ/mol
  • 3rd: 2997 kJ/mol
Atomic radius empirical:134  pm
Covalent radius 142±7 pm
Rhodium spectrum visible.png
Spectral lines of rhodium
Other properties
Natural occurrence primordial
Crystal structure face-centered cubic (fcc)(cF4)
Lattice constant
a = 380.34 pm (at 20 °C) [3]
Thermal expansion 8.46×10−6/K (at 20 °C) [3]
Thermal conductivity 150 W/(m⋅K)
Electrical resistivity 43.3 nΩ⋅m(at 0 °C)
Magnetic ordering paramagnetic [6]
Molar magnetic susceptibility +111.0×10−6 cm3/mol(298 K) [7]
Young's modulus 380 GPa
Shear modulus 150 GPa
Bulk modulus 275 GPa
Speed of sound thin rod4700 m/s(at 20 °C)
Poisson ratio 0.26
Mohs hardness 6.0
Vickers hardness 1100–8000 MPa
Brinell hardness 980–1350 MPa
CAS Number 7440-16-6
Discovery and first isolation William Hyde Wollaston (1804)
Isotopes of rhodium
Main isotopes [8] Decay
abun­dance half-life (t1/2) mode pro­duct
99Rh synth 16.1 d β+ 99Ru
101Rhsynth4.07 y ε 101Ru
101mRhsynth4.343 dε 101Ru
IT 101Rh
102Rhsynth207 dβ+ 102Ru
β 102Pd
102mRhsynth3.742 yβ+102Ru
103Rh100% stable
105Rhsynth35.341 hβ 105Pd
Symbol category class.svg  Category: Rhodium
| references

Rhodium is a chemical element; it has symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isotope, which is 103Rh. Naturally occurring rhodium is usually found as a free metal or as an alloy with similar metals and rarely as a chemical compound in minerals such as bowieite and rhodplumsite. It is one of the rarest and most valuable precious metals.


Rhodium is found in platinum or nickel ores with the other members of the platinum group metals. It was discovered in 1803 by William Hyde Wollaston in one such ore, and named for the rose color of one of its chlorine compounds.

The element's major use (consuming about 80% of world rhodium production) is as one of the catalysts in the three-way catalytic converters in automobiles. Because rhodium metal is inert against corrosion and most aggressive chemicals, and because of its rarity, rhodium is usually alloyed with platinum or palladium and applied in high-temperature and corrosion-resistive coatings. White gold is often plated with a thin rhodium layer to improve its appearance, while sterling silver is often rhodium-plated to resist tarnishing. Rhodium is sometimes used to cure silicones: a two-part silicone in which one part containing a silicon hydride and the other containing a vinyl-terminated silicone are mixed; one of these liquids contains a rhodium complex. [9]

Rhodium detectors are used in nuclear reactors to measure the neutron flux level. Other uses of rhodium include asymmetric hydrogenation used to form drug precursors and the processes for the production of acetic acid.


William Hyde Wollaston Wollaston William Hyde Jackson color.jpg
William Hyde Wollaston

Rhodium (Greek rhodon (ῥόδον) meaning "rose") was discovered in 1803 by William Hyde Wollaston, [10] soon after he discovered palladium. [11] [12] [13] He used crude platinum ore presumably obtained from South America. [14] His procedure dissolved the ore in aqua regia and neutralized the acid with sodium hydroxide (NaOH). He then precipitated the platinum as ammonium chloroplatinate by adding ammonium chloride (NH
). Most other metals like copper, lead, palladium, and rhodium were precipitated with zinc. Diluted nitric acid dissolved all but palladium and rhodium. Of these, palladium dissolved in aqua regia but rhodium did not, [15] and the rhodium was precipitated by the addition of sodium chloride as Na
. After being washed with ethanol, the rose-red precipitate was reacted with zinc, which displaced the rhodium in the ionic compound and thereby released the rhodium as free metal. [16]

For decades, the rare element had only minor applications; for example, by the turn of the century, rhodium-containing thermocouples were used to measure temperatures up to 1800 °C. [17] [18] They have exceptionally good stability in the temperature range of 1300 to 1800 °C. [19]

The first major application was electroplating for decorative uses and as corrosion-resistant coating. [20] The introduction of the three-way catalytic converter by Volvo in 1976 increased the demand for rhodium. The previous catalytic converters used platinum or palladium, while the three-way catalytic converter used rhodium to reduce the amount of NOx in the exhaust. [21] [22] [23]


Z Element No. of electrons/shell
27cobalt2, 8, 15, 2
45rhodium2, 8, 18, 16, 1
77iridium2, 8, 18, 32, 15, 2
109meitnerium2, 8, 18, 32, 32, 15, 2 (predicted)

Rhodium is a hard, silvery, durable metal that has a high reflectance. Rhodium metal does not normally form an oxide, even when heated. [24] Oxygen is absorbed from the atmosphere only at the melting point of rhodium, but is released on solidification. [25] Rhodium has both a higher melting point and lower density than platinum. It is not attacked by most acids: it is completely insoluble in nitric acid and dissolves slightly in aqua regia.

Chemical properties

Wilkinson's catalyst Wilkinson's-catalyst-2D.png
Wilkinson's catalyst

Rhodium belongs to group 9 of the periodic table, but exhibits an atypical ground state valence electron configuration for that group. Like neighboring elements niobium (41), ruthenium (44), and palladium (46), it only has one electron in its outermost s orbital.

Oxidation states
of rhodium
, Rh
, Sr

The common oxidation state of rhodium is +3, but oxidation states from 0 to +7 are also observed. [26] [27]

Unlike ruthenium and osmium, rhodium forms no volatile oxygen compounds. The known stable oxides include Rh
, RhO
, RhO
, Na
, Sr
and Sr
. [28] Halogen compounds are known in nearly the full range of possible oxidation states. Rhodium(III) chloride, rhodium trifluoride, rhodium pentafluoride and rhodium hexafluoride are examples. The lower oxidation states are stable only in the presence of ligands. [29]

The best-known rhodium-halogen compound is the Wilkinson's catalyst chlorotris(triphenylphosphine)rhodium(I). This catalyst is used in the hydroformylation or hydrogenation of alkenes. [30]


Naturally occurring rhodium is composed of only one isotope, 103Rh. The most stable radioisotopes are 101Rh with a half-life of 3.3 years, 102Rh with a half-life of 207 days, 102mRh with a half-life of 2.9 years, and 99Rh with a half-life of 16.1 days. Twenty other radioisotopes have been characterized with atomic weights ranging from 92.926 u (93Rh) to 116.925 u (117Rh). Most of these have half-lives shorter than an hour, except 100Rh (20.8 hours) and 105Rh (35.36 hours). Rhodium has numerous meta states, the most stable being 102mRh (0.141 MeV) with a half-life of about 2.9 years and 101mRh (0.157 MeV) with a half-life of 4.34 days (see isotopes of rhodium). [31]

In isotopes weighing less than 103 (the stable isotope), the primary decay mode is electron capture and the primary decay product is ruthenium. In isotopes greater than 103, the primary decay mode is beta emission and the primary product is palladium. [32]


Rhodium is one of the rarest elements in the Earth's crust, comprising an estimated 0.0002 parts per million (2 × 10−10). [33] It is only the 79th most abundant element in the crust. Its rarity affects its price and its use in commercial applications. The concentration of rhodium in nickel meteorites is typically 1 part per billion. [34] Rhodium has been measured in some potatoes with concentrations between 0.8 and 30 ppt. [35]

Mining and price

Rh price evolution Rh price.png
Rh price evolution
Rhodium daily price 1992-2022 Rhodium daily Price 1992-2022.webp
Rhodium daily price 1992–2022

The industrial extraction of rhodium is complex because the ores are mixed with other metals such as palladium, silver, platinum, and gold and there are very few rhodium-bearing minerals. It is found in platinum ores and extracted as a white inert metal that is difficult to fuse. Principal sources are located in South Africa; in river sands of the Ural Mountains in Russia; and in North America, including the copper-nickel sulfide mining area of the Sudbury, Ontario, region. Although the rhodium abundance at Sudbury is very small, the large amount of processed nickel ore makes rhodium recovery cost-effective.

The main exporter of rhodium is South Africa (approximately 80% in 2010) followed by Russia. [36] The annual world production is 30 tonnes. The price of rhodium is highly variable.

Used nuclear fuels

Rhodium is a fission product of uranium-235: each kilogram of fission product contains a significant amount of the lighter platinum group metals. Used nuclear fuel is therefore a potential source of rhodium, but the extraction is complex and expensive, and the presence of rhodium radioisotopes requires a period of cooling storage for multiple half-lives of the longest-lived isotope (101Rh with a half-life of 3.3 years, and 102mRh with a half-life of 2.9 years), or about 10 years. These factors make the source unattractive and no large-scale extraction has been attempted. [37] [38] [39]


The primary use of this element is in automobiles as a catalytic converter, changing harmful unburned hydrocarbons, carbon monoxide, and nitrogen oxide exhaust emissions into less noxious gases. Of 30,000 kg of rhodium consumed worldwide in 2012, 81% (24,300 kg) went into this application, and 8,060 kg was recovered from old converters. About 964 kg of rhodium was used in the glass industry, mostly for production of fiberglass and flat-panel glass, and 2,520 kg was used in the chemical industry. [36]


Rhodium is preferable to the other platinum metals in the reduction of nitrogen oxides to nitrogen and oxygen: [40]

2 NO
+ N

In 2008, net demand (with the recycling accounted for) of rhodium for automotive converters made up 84% of the world usage, [41] with the number fluctuating around 80% in 2015−2021. [42]

Rhodium catalysts are used in a number of industrial processes, notably in catalytic carbonylation of methanol to produce acetic acid by the Monsanto process. [43] It is also used to catalyze addition of hydrosilanes to molecular double bonds, a process important in manufacture of certain silicone rubbers. [44] Rhodium catalysts are also used to reduce benzene to cyclohexane. [45]

The complex of a rhodium ion with BINAP is a widely used chiral catalyst for chiral synthesis, as in the synthesis of menthol. [46]

Ornamental uses

Rhodium finds use in jewelry and for decorations. It is electroplated on white gold and platinum to give it a reflective white surface at time of sale, after which the thin layer wears away with use. This is known as rhodium flashing in the jewelry business. It may also be used in coating sterling silver to protect against tarnish (silver sulfide, Ag2S, produced from atmospheric hydrogen sulfide, H2S). Solid (pure) rhodium jewelry is very rare, more because of the difficulty of fabrication (high melting point and poor malleability) than because of the high price. [47] The high cost ensures that rhodium is applied only as an electroplate. Rhodium has also been used for honors or to signify elite status, when more commonly used metals such as silver, gold or platinum were deemed insufficient. In 1979 the Guinness Book of World Records gave Paul McCartney a rhodium-plated disc for being history's all-time best-selling songwriter and recording artist. [48]

Other uses

Rhodium is used as an alloying agent for hardening and improving the corrosion resistance [24] of platinum and palladium. These alloys are used in furnace windings, bushings for glass fiber production, thermocouple elements, electrodes for aircraft spark plugs, and laboratory crucibles. [49] Other uses include:

In automobile manufacturing, rhodium is also used in the construction of headlight reflectors. [54]


GHS labelling:
P273, P501 [55]
NFPA 704 (fire diamond)
NFPA 704.svgHealth 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code

Being a noble metal, pure rhodium is inert and harmless in elemental form. [56] However, chemical complexes of rhodium can be reactive. For rhodium chloride, the median lethal dose (LD50) for rats is 198 mg (RhCl
) per kilogram of body weight. [57] Like the other noble metals, rhodium has not been found to serve any biological function.

People can be exposed to rhodium in the workplace by inhalation. The Occupational Safety and Health Administration (OSHA) has specified the legal limit (Permissible exposure limit) for rhodium exposure in the workplace at 0.1 mg/m3 over an 8-hour workday, and the National Institute for Occupational Safety and Health (NIOSH) has set the recommended exposure limit (REL), at the same level. At levels of 100 mg/m3, rhodium is immediately dangerous to life or health. [58] For soluble compounds, the PEL and REL are both 0.001 mg/m3. [59]

See also

Related Research Articles

<span class="mw-page-title-main">Iridium</span> Chemical element, symbol Ir and atomic number 77

Iridium is a chemical element; it has symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal with a density of 22.56 g/cm3 (0.815 lb/cu in) as defined by experimental X-ray crystallography. 191Ir and 193Ir are the only two naturally occurring isotopes of iridium, as well as the only stable isotopes; the latter is the more abundant. It is one of the most corrosion-resistant metals, even at temperatures as high as 2,000 °C (3,630 °F).

<span class="mw-page-title-main">Osmium</span> Chemical element, symbol Os and atomic number 76

Osmium is a chemical element; it has symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element. When experimentally measured using X-ray crystallography, it has a density of 22.59 g/cm3. Manufacturers use its alloys with platinum, iridium, and other platinum-group metals to make fountain pen nib tipping, electrical contacts, and in other applications that require extreme durability and hardness.

<span class="mw-page-title-main">Palladium</span> Chemical element, symbol Pd and atomic number 46

Palladium is a chemical element; it has symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1802 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). They have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.

<span class="mw-page-title-main">Platinum</span> Chemical element, symbol Pt and atomic number 78

Platinum is a chemical element; it has symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish platina, a diminutive of plata "silver".

<span class="mw-page-title-main">Ruthenium</span> Chemical element, symbol Ru and atomic number 44

Ruthenium is a chemical element; it has symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals. Karl Ernst Claus, a Russian-born scientist of Baltic-German ancestry, discovered the element in 1844 at Kazan State University and named ruthenium in honor of Russia. Ruthenium is usually found as a minor component of platinum ores; the annual production has risen from about 19 tonnes in 2009 to some 35.5 tonnes in 2017. Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for ruthenium is in platinum alloys and as a chemistry catalyst. A new application of ruthenium is as the capping layer for extreme ultraviolet photomasks. Ruthenium is generally found in ores with the other platinum group metals in the Ural Mountains and in North and South America. Small but commercially important quantities are also found in pentlandite extracted from Sudbury, Ontario, and in pyroxenite deposits in South Africa.

A period 5 element is one of the chemical elements in the fifth row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fifth period contains 18 elements, beginning with rubidium and ending with xenon. As a rule, period 5 elements fill their 5s shells first, then their 4d, and 5p shells, in that order; however, there are exceptions, such as rhodium.

<span class="mw-page-title-main">Noble metal</span> Metallic elements that are nearly chemically inert

A noble metal is ordinarily regarded as a metallic chemical element that is generally resistant to corrosion and is usually found in nature in its raw form. Gold, platinum, and the other platinum group metals are most often so classified. Silver, copper, and mercury are sometimes included as noble metals, but each of these usually occurs in nature combined with sulfur.

<span class="mw-page-title-main">Hydrogenation</span> Chemical reaction between molecular hydrogen and another compound or element

Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, often an alkene. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Hydrogenation reduces double and triple bonds in hydrocarbons.

<span class="mw-page-title-main">Catalytic converter</span> Exhaust emission control device

A catalytic converter is an exhaust emission control device which converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalyzing a redox reaction. Catalytic converters are usually used with internal combustion engines fueled by gasoline or diesel, including lean-burn engines, and sometimes on kerosene heaters and stoves.

The platinum-group metals (PGMs), also known as the platinoids, platinides, platidises, platinum group, platinum metals, platinum family or platinum-group elements (PGEs), are six noble, precious metallic elements clustered together in the periodic table. These elements are all transition metals in the d-block.

<span class="mw-page-title-main">Group 9 element</span> Group of chemical elements

Group 9, by modern IUPAC numbering, is a group (column) of chemical elements in the d-block of the periodic table. Members of Group 9 include cobalt (Co), rhodium (Rh), iridium (Ir) and meitnerium (Mt). These elements are among the rarest of the transition metals.

<span class="mw-page-title-main">Wilkinson's catalyst</span> Chemical compound

Wilkinson's catalyst (chlorido­tris(triphenylphosphene)­rhodium(I)) is a coordination complex of rhodium with the formula [RhCl(PPh3)3], where 'Ph' denotes a phenyl group. It is a red-brown colored solid that is soluble in hydrocarbon solvents such as benzene, and more so in tetrahydrofuran or chlorinated solvents such as dichloromethane. The compound is widely used as a catalyst for hydrogenation of alkenes. It is named after chemist and Nobel laureate Sir Geoffrey Wilkinson, who first popularized its use.

<span class="mw-page-title-main">Rhodium(III) chloride</span> Chemical compound

Rhodium(III) chloride refers to inorganic compounds with the formula RhCl3(H2O)n, where n varies from 0 to 3. These are diamagnetic solids featuring octahedral Rh(III) centres. Depending on the value of n, the material is either a dense brown solid or a soluble reddish salt. The soluble trihydrated (n = 3) salt is widely used to prepare compounds used in homogeneous catalysis, notably for the industrial production of acetic acid and hydroformylation.

Adams' catalyst, also known as platinum dioxide, is usually represented as platinum(IV) oxide hydrate, PtO2•H2O. It is a catalyst for hydrogenation and hydrogenolysis in organic synthesis. This dark brown powder is commercially available. The oxide itself is not an active catalyst, but it becomes active after exposure to hydrogen whereupon it converts to platinum black, which is responsible for reactions.

Natural palladium (46Pd) is composed of six stable isotopes, 102Pd, 104Pd, 105Pd, 106Pd, 108Pd, and 110Pd, although 102Pd and 110Pd are theoretically unstable. The most stable radioisotopes are 107Pd with a half-life of 6.5 million years, 103Pd with a half-life of 17 days, and 100Pd with a half-life of 3.63 days. Twenty-three other radioisotopes have been characterized with atomic weights ranging from 90.949 u (91Pd) to 128.96 u (129Pd). Most of these have half-lives that are less than a half an hour except 101Pd, 109Pd, and 112Pd.

Nanomaterial-based catalysts are usually heterogeneous catalysts broken up into metal nanoparticles in order to enhance the catalytic process. Metal nanoparticles have high surface area, which can increase catalytic activity. Nanoparticle catalysts can be easily separated and recycled. They are typically used under mild conditions to prevent decomposition of the nanoparticles.

<span class="mw-page-title-main">Rhodium(III) oxide</span> Chemical compound

Rhodium(III) oxide (or Rhodium sesquioxide) is the inorganic compound with the formula Rh2O3. It is a gray solid that is insoluble in ordinary solvents.

<span class="mw-page-title-main">Organorhodium chemistry</span> Field of study

Organorhodium chemistry is the chemistry of organometallic compounds containing a rhodium-carbon chemical bond, and the study of rhodium and rhodium compounds as catalysts in organic reactions.

Rhodium-platinum oxide , or Nishimura's catalyst, is an inorganic compound used as a hydrogenation catalyst.

<span class="mw-page-title-main">Activation of cyclopropanes by transition metals</span>

In organometallic chemistry, the activation of cyclopropanes by transition metals is a research theme with implications for organic synthesis and homogeneous catalysis. Being highly strained, cyclopropanes are prone to oxidative addition to transition metal complexes. The resulting metallacycles are susceptible to a variety of reactions. These reactions are rare examples of C-C bond activation. The rarity of C-C activation processes has been attributed to Steric effects that protect C-C bonds. Furthermore, the directionality of C-C bonds as compared to C-H bonds makes orbital interaction with transition metals less favorable. Thermodynamically, C-C bond activation is more favored than C-H bond activation as the strength of a typical C-C bond is around 90 kcal per mole while the strength of a typical unactivated C-H bond is around 104 kcal per mole.


  1. "Standard Atomic Weights: Rhodium". CIAAW. 2017.
  2. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN   1365-3075.
  3. 1 2 3 Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN   978-1-62708-155-9.
  4. Ellis J E. Highly Reduced Metal Carbonyl Anions: Synthesis, Characterization, and Chemical Properties. Adv. Organomet. Chem, 1990, 31: 1-51.
  5. Rh(VII) is known in the RhO3+ cation, see Da Silva Santos, Mayara; Stüker, Tony; Flach, Max; Ablyasova, Olesya S.; Timm, Martin; von Issendorff, Bernd; Hirsch, Konstantin; Zamudio‐Bayer, Vicente; Riedel, Sebastian; Lau, J. Tobias (2022). "The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+". Angew. Chem. Int. Ed. 61 (38): e202207688. doi:10.1002/anie.202207688. PMC   9544489 . PMID   35818987.
  6. Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN   0-8493-0486-5.
  7. Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN   0-8493-0464-4.
  8. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  9. Armin Fehn and Juergen Weidinger, Wacker Chemie AG, US patent US7129309B2
  10. Wollaston, W. H. (1804). "On a New Metal, Found in Crude Platina". Philosophical Transactions of the Royal Society of London . 94: 419–430. doi: 10.1098/rstl.1804.0019 .
  11. Griffith, W. P. (2003). "Rhodium and Palladium – Events Surrounding Its Discovery". Platinum Metals Review. 47 (4): 175–183.
  12. Wollaston, W. H. (1805). "On the Discovery of Palladium; With Observations on Other Substances Found with Platina". Philosophical Transactions of the Royal Society of London . 95: 316–330. doi: 10.1098/rstl.1805.0024 .
  13. Usselman, Melvyn (1978). "The Wollaston/Chenevix controversy over the elemental nature of palladium: A curious episode in the history of chemistry". Annals of Science. 35 (6): 551–579. doi:10.1080/00033797800200431.
  14. Lide, David R. (2004). CRC handbook of chemistry and physics: a ready-reference book of chemical and physical data . Boca Raton: CRC Press. pp.  4–26. ISBN   978-0-8493-0485-9.
  15. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 1113. ISBN   978-0-08-037941-8.
  16. Griffith, W. P. (2003). "Bicentenary of Four Platinum Group Metals: Osmium and iridium – events surrounding their discoveries". Platinum Metals Review. 47 (4): 175–183.
  17. Hulett, G. A.; Berger, H. W. (1904). "Volatilization of Platinum". Journal of the American Chemical Society. 26 (11): 1512–1515. doi:10.1021/ja02001a012. Archived (PDF) from the original on 24 January 2024 via Zenodo.
  18. ASTM Committee E.2.0. on Temperature Measurement (1993). "Platinum Type". Manual on the use of thermocouples in temperature measurement. ASTM Special Technical Publication. ASTM International. Bibcode:1981mutt.book.....B. ISBN   978-0-8031-1466-1.
  19. J.V. Pearce, F. Edler, C.J. Elliott, A. Greenen, P.M. Harris, C.G. Izquierdo, Y.G. Kim, M.J. Martin, I.M. Smith, D. Tucker and R.I. Veitcheva, A systematic investigation of the thermoelectric stability of Pt-Rh thermocouples between 1300 °C and 1500 °C, METROLOGIA, 2018, Volume: 55 Issue: 4 Pages: 558-567
  20. Kushner, Joseph B. (1940). "Modern rhodium plating". Metals and Alloys. 11: 137–140.
  21. Amatayakul, W.; Ramnäs, Olle (2001). "Life cycle assessment of a catalytic converter for passenger cars". Journal of Cleaner Production. 9 (5): 395. doi:10.1016/S0959-6526(00)00082-2.
  22. Heck, R.; Farrauto, Robert J. (2001). "Automobile exhaust catalysts". Applied Catalysis A: General. 221 (1–2): 443–457. doi:10.1016/S0926-860X(01)00818-3.
  23. Heck, R.; Gulati, Suresh; Farrauto, Robert J. (2001). "The application of monoliths for gas phase catalytic reactions". Chemical Engineering Journal. 82 (1–3): 149–156. doi:10.1016/S1385-8947(00)00365-X.
  24. 1 2 Cramer, Stephen D.; Covino, Bernard S. Jr., eds. (1990). ASM handbook. Materials Park, OH: ASM International. pp. 393–396. ISBN   978-0-87170-707-9.
  25. Emsley, John (2001). Nature's Building Blocks ((Hardcover, First Edition) ed.). Oxford University Press. p.  363. ISBN   978-0-19-850340-8.
  26. Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). Lehrbuch der Anorganischen Chemie (91–100 ed.). Walter de Gruyter. pp. 1056–1057. ISBN   978-3-11-007511-3.
  27. Mayara da Silva Santos, Tony Stüker, Max Flach, Olesya S. Ablyasova, Martin Timm, Bernd von Issendorff, Konstantin Hirsch, Vicente Zamudio‐Bayer, Sebastian Riedel, J. Tobias Lau. The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO 3 ] +. Angewandte Chemie International Edition, 2022; 61 (38)
  28. Reisner, B. A.; Stacy, A. M. (1998). "Sr
    (A = Li, Na): Crystallization of a Rhodium(V) Oxide from Molten Hydroxide". Journal of the American Chemical Society. 120 (37): 9682–9989. doi:10.1021/ja974231q.
  29. Griffith, W. P. The Rarer Platinum Metals, John Wiley and Sons: New York, 1976, p. 313.
  30. Osborn, J. A.; Jardine, F. H.; Young, J. F.; Wilkinson, G. (1966). "The Preparation and Properties of Tris(triphenylphosphine)halogenorhodium(I) and Some Reactions Thereof Including Catalytic Homogeneous Hydrogenation of Olefins and Acetylenes and Their Derivatives". Journal of the Chemical Society A : 1711–1732. doi:10.1039/J19660001711.
  31. Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  32. David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.
  33. Barbalace, Kenneth, "Table of Elements". Environmental Chemistry.com; retrieved 2007-04-14.
  34. D.E.Ryan, J.Holzbecher and R.R.Brooks, Chemical Geology, Volume 85, Issues 3–4, 30 July 1990, Pages 295-303
  35. Orecchio and Amorello, Foods, 2019, volume 8, issue 2, doi : 10.3390/foods8020059
  36. 1 2 Loferski, Patricia J. (2013). "Commodity Report: Platinum-Group Metals" (PDF). United States Geological Survey. Retrieved 16 July 2012.
  37. Kolarik, Zdenek; Renard, Edouard V. (2005). "Potential Applications of Fission Platinoids in Industry" (PDF). Platinum Metals Review. 49 (2): 79. doi: 10.1595/147106705X35263 .
  38. Kolarik, Zdenek; Renard, Edouard V. (2003). "Recovery of Value Fission Platinoids from Spent Nuclear Fuel. Part I PART I: General Considerations and Basic Chemistry" (PDF). Platinum Metals Review. 47 (2): 74–87.
  39. Kolarik, Zdenek; Renard, Edouard V. (2003). "Recovery of Value Fission Platinoids from Spent Nuclear Fuel. Part II: Separation Process" (PDF). Platinum Metals Review. 47 (2): 123–131.
  40. Shelef, M.; Graham, G. W. (1994). "Why Rhodium in Automotive Three-Way Catalysts?". Catalysis Reviews. 36 (3): 433–457. doi:10.1080/01614949408009468.
  41. Murray, Angela Janet (2012). Recovery of Platinum Group Metals from Spent Furnace Linings and Used Automotive Catalysts (PDF) (PhD thesis). University of Birmingham.
  42. "The Rhodium Market and Rhodium Price".
  43. Roth, James F. (1975). "Rhodium Catalysed Carbonylation of Methanol" (PDF). Platinum Metals Review. 19 (1 January): 12–14.
  44. Heidingsfeldova, M. & Capka, M. (2003). "Rhodium complexes as catalysts for hydrosilylation crosslinking of silicone rubber". Journal of Applied Polymer Science. 30 (5): 1837. doi:10.1002/app.1985.070300505.
  45. Halligudi, S. B.; et al. (1992). "Hydrogenation of benzene to cyclohexane catalyzed by rhodium(I) complex supported on montmorillonite clay". Reaction Kinetics and Catalysis Letters. 48 (2): 547. Bibcode:1992RKCL...48..505T. doi:10.1007/BF02162706. S2CID   97802315.
  46. Akutagawa, S. (1995). "Asymmetric synthesis by metal BINAP catalysts". Applied Catalysis A: General. 128 (2): 171. doi:10.1016/0926-860X(95)00097-6.
  47. Fischer, Torkel; Fregert, S.; Gruvberger, B.; Rystedt, I. (1984). "Contact sensitivity to nickel in white gold". Contact Dermatitis. 10 (1): 23–24. doi:10.1111/j.1600-0536.1984.tb00056.x. PMID   6705515. S2CID   46626556.
  48. "Hit & Run: Ring the changes". The Independent . London. 2 December 2008. Retrieved 6 June 2009.
  49. Lide, David R (2004). CRC handbook of chemistry and physics 2004–2005: a ready-reference book of chemical and physical data (85th ed.). Boca Raton: CRC Press. pp. 4–26. ISBN   978-0-8493-0485-9.
  50. Weisberg, Alfred M. (1999). "Rhodium plating". Metal Finishing. 97 (1): 296–299. doi:10.1016/S0026-0576(00)83088-3.
  51. Smith, Warren J. (2007). "Reflectors". Modern optical engineering: the design of optical systems. McGraw-Hill. pp. 247–248. ISBN   978-0-07-147687-4.
  52. McDonagh, C P; et al. (1984). "Optimum x-ray spectra for mammography: choice of K-edge filters for tungsten anode tubes". Phys. Med. Biol. 29 (3): 249–52. Bibcode:1984PMB....29..249M. doi:10.1088/0031-9155/29/3/004. PMID   6709704. S2CID   250873106.
  53. Sokolov, A. P.; Pochivalin, G. P.; Shipovskikh, Yu. M.; Garusov, Yu. V.; Chernikov, O. G.; Shevchenko, V. G. (1993). "Rhodium self-powered detector for monitoring neutron fluence, energy production, and isotopic composition of fuel". Atomic Energy. 74 (5): 365–367. doi:10.1007/BF00844622. S2CID   96175609.
  54. Stwertka, Albert. A Guide to the Elements, Oxford University Press, 1996, p. 125. ISBN   0-19-508083-1
  55. "MSDS - 357340". www.sigmaaldrich.com.
  56. Leikin, Jerrold B.; Paloucek Frank P. (2008). Poisoning and Toxicology Handbook. Informa Health Care. p. 846. ISBN   978-1-4200-4479-9.
  57. Landolt, Robert R.; Berk Harold W.; Russell, Henry T. (1972). "Studies on the toxicity of rhodium trichloride in rats and rabbits". Toxicology and Applied Pharmacology . 21 (4): 589–590. doi:10.1016/0041-008X(72)90016-6. PMID   5047055.
  58. "NIOSH Pocket Guide to Chemical Hazards - Rhodium (metal fume and insoluble compounds, as Rh)". CDC. Retrieved 21 November 2015.
  59. "NIOSH Pocket Guide to Chemical Hazards - Rhodium (soluble compounds, as Rh)". CDC. Retrieved 21 November 2015.