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Hub AI
Iridium compounds AI simulator
(@Iridium compounds_simulator)
Hub AI
Iridium compounds AI simulator
(@Iridium compounds_simulator)
Iridium compounds
Iridium compounds are compounds containing the element iridium (Ir). Iridium forms compounds in oxidation states between −3 and +9, but the most common oxidation states are +1, +2, +3, and +4. Well-characterized compounds containing iridium in the +6 oxidation state include IrF6 and the oxides Sr2MgIrO6 and Sr2CaIrO6. iridium(VIII) oxide (IrO4) was generated under matrix isolation conditions at 6 K in argon. The highest oxidation state (+9), which is also the highest recorded for any element, is found in gaseous [IrO4]+.
Only one binary oxide is well-characterized: Iridium dioxide, IrO
2. It is a blue-black solid. The compound adopts the TiO2 rutile structure, featuring six coordinate iridium and three coordinate oxygen. It adopts the fluorite structure. A sesquioxide, Ir
2O
3, has been described as a blue-black powder, which is oxidized to IrO
2 by HNO
3. The corresponding disulfides, diselenides, sesquisulfides, and sesquiselenides are known, as well as IrS
3.
Another oxide, iridium tetroxide, is also known, with iridium in the +8 oxiation state. This compound was formed by photochemical rearrangement of [(η1-O2)IrO2] in solid argon at a temperature of 6 K (−267.15 °C; −448.87 °F). At higher temperatures, the oxide is unstable. The detection of the iridium tetroxide cation IrO+
4 by infrared photodissociation spectroscopy with formal oxidation state +9 has been reported, the highest currently known of any element, though the +10 oxidation state has been theorized for platinum, but not confirmed.
Binary trihalides, IrX
3 are known for all of the halogens. For oxidation states +4 and above, only the tetrafluoride, pentafluoride and hexafluoride are known. Iridium hexafluoride, IrF
6, is a volatile yellow solid, composed of octahedral molecules. It decomposes in water and is reduced to IrF
4,. Iridium pentafluoride is also a strong oxidant, but it is a tetramer, Ir
4F
20, formed by four corner-sharing octahedra.
The coordination complexes of iridium are extensive.
Iridium in its complexes is always low-spin. Ir(III) and Ir(IV) generally form octahedral complexes. Polyhydride complexes are known for the +5 and +3 oxidation states. One example is IrH5(PiPr3)2. The ternary hydride Mg
6Ir
2H
11 is believed to contain both the IrH4−
5 and the 18-electron IrH5−
4 anion.
Iridium also oxyanions with oxidation states +4 and +5. K
2IrO
3 and KIrO
3 can be prepared from the reaction of potassium oxide or potassium superoxide with iridium at high temperatures. Such solids are not soluble in conventional solvents.
As for many elements, the chlorides are key complexes. Hexachloroiridic(IV) acid, H
2IrCl
6, and its ammonium salt are the most common iridium compounds from an industrial and preparative perspectives. They are intermediates in the purification of iridium and used as precursors for most other iridium compounds, as well as in the preparation of anode coatings. The IrCl2−
6 ion has an intense dark brown color, and can be readily reduced to the lighter-colored IrCl3−
6 and vice versa. Iridium trichloride, IrCl
3, which can be obtained in anhydrous form from direct oxidation of iridium powder by chlorine at 650 °C, or in hydrated form by dissolving Ir
2O
3 in hydrochloric acid, is often used as a starting material for the synthesis of other Ir(III) compounds. Another compound used as a starting material is ammonium hexachloroiridate(III), (NH
4)
3IrCl
6.
Iridium compounds
Iridium compounds are compounds containing the element iridium (Ir). Iridium forms compounds in oxidation states between −3 and +9, but the most common oxidation states are +1, +2, +3, and +4. Well-characterized compounds containing iridium in the +6 oxidation state include IrF6 and the oxides Sr2MgIrO6 and Sr2CaIrO6. iridium(VIII) oxide (IrO4) was generated under matrix isolation conditions at 6 K in argon. The highest oxidation state (+9), which is also the highest recorded for any element, is found in gaseous [IrO4]+.
Only one binary oxide is well-characterized: Iridium dioxide, IrO
2. It is a blue-black solid. The compound adopts the TiO2 rutile structure, featuring six coordinate iridium and three coordinate oxygen. It adopts the fluorite structure. A sesquioxide, Ir
2O
3, has been described as a blue-black powder, which is oxidized to IrO
2 by HNO
3. The corresponding disulfides, diselenides, sesquisulfides, and sesquiselenides are known, as well as IrS
3.
Another oxide, iridium tetroxide, is also known, with iridium in the +8 oxiation state. This compound was formed by photochemical rearrangement of [(η1-O2)IrO2] in solid argon at a temperature of 6 K (−267.15 °C; −448.87 °F). At higher temperatures, the oxide is unstable. The detection of the iridium tetroxide cation IrO+
4 by infrared photodissociation spectroscopy with formal oxidation state +9 has been reported, the highest currently known of any element, though the +10 oxidation state has been theorized for platinum, but not confirmed.
Binary trihalides, IrX
3 are known for all of the halogens. For oxidation states +4 and above, only the tetrafluoride, pentafluoride and hexafluoride are known. Iridium hexafluoride, IrF
6, is a volatile yellow solid, composed of octahedral molecules. It decomposes in water and is reduced to IrF
4,. Iridium pentafluoride is also a strong oxidant, but it is a tetramer, Ir
4F
20, formed by four corner-sharing octahedra.
The coordination complexes of iridium are extensive.
Iridium in its complexes is always low-spin. Ir(III) and Ir(IV) generally form octahedral complexes. Polyhydride complexes are known for the +5 and +3 oxidation states. One example is IrH5(PiPr3)2. The ternary hydride Mg
6Ir
2H
11 is believed to contain both the IrH4−
5 and the 18-electron IrH5−
4 anion.
Iridium also oxyanions with oxidation states +4 and +5. K
2IrO
3 and KIrO
3 can be prepared from the reaction of potassium oxide or potassium superoxide with iridium at high temperatures. Such solids are not soluble in conventional solvents.
As for many elements, the chlorides are key complexes. Hexachloroiridic(IV) acid, H
2IrCl
6, and its ammonium salt are the most common iridium compounds from an industrial and preparative perspectives. They are intermediates in the purification of iridium and used as precursors for most other iridium compounds, as well as in the preparation of anode coatings. The IrCl2−
6 ion has an intense dark brown color, and can be readily reduced to the lighter-colored IrCl3−
6 and vice versa. Iridium trichloride, IrCl
3, which can be obtained in anhydrous form from direct oxidation of iridium powder by chlorine at 650 °C, or in hydrated form by dissolving Ir
2O
3 in hydrochloric acid, is often used as a starting material for the synthesis of other Ir(III) compounds. Another compound used as a starting material is ammonium hexachloroiridate(III), (NH
4)
3IrCl
6.