Samarium(II) iodide

Samarium diiodide

Dark green crystals

Fixed

~ 840 ° C ( decomposition)

Moderately in tetrahydrofuran

Template: Infobox chemical / molecular formula search available

Samarium ( II) iodide ( SmI2 ) is a chemical compound of the elements of samarium and iodine. Samarium ( II) iodide is a deep green to black solid dissolves in water to give a deep red color. Its particular importance was it only through its diverse use in syntheses in the organic chemistry. Samarium ( II) iodide was introduced together with the ytterbium ( II) iodide ( YbI2 ) as a reagent for organic synthesis.

Representation

Samarium is one of the lanthanoids and has the electron configuration [ Xe] 6s2 4F6. In its compounds it is preferably present in the oxidation state 3, and rarely in the 2 oxidation state.

About samarium ( II) iodide was first reported in 1906. Samarium ( II) iodide is not accessible by direct reaction of the elements in this way forms only samarium ( III ) iodide.

The representation of samarium ( II) iodide is achieved by reduction of anhydrous samarium (III ) iodide in a stream of hydrogen at about 750 ° C:

The representation of samarium ( II) iodide may also be effected by reduction of samarium (III ) iodide with metallic samarium:

Establishes the presentation on samarium and 1,2- diiodoethane has in tetrahydrofuran ( THF). Although the reaction proceeds at room temperature, but due to the sensitivity of the reagents to operate under inert gas and anhydrous. In the presence of oxygen, otherwise there is a rapid oxidation of the samarium ( III). This is visually recognizable by the color change from dark blue to yellow solution. The reagent is commercially available as dark blue 0.1 M solution in THF, however, is unstable in the long run, so it should be better prepared fresh.

Furthermore, samarium with mercury ( II) iodide or iodine in THF can be reacted.

Properties

Samarium ( II) iodide is a deep green and black solid which dissolves in water with a deep red color. The redox potential of Sm2 / Sm3 is -1.55 V, so it is a strong reducing agent. Samarium ( II) iodide is also very air-and moisture-sensitive. It oxidizes rapidly in air to samarium ( III). The aqueous solution decomposes over the course of about 15 min with evolution of hydrogen and extensive discoloration; this is basic iodides are deposited. With acids, the reaction proceeds stormy.

SmI2 starts at 0.01 Torr at 680 ° C again in Sm and to disproportionate SmI3 and melts with decomposition at 840 ° C clearly; here are the SmI3 turn from iodine. The melting point can not be determined exactly.

Use

Samarium ( II) iodide is a great variety of standard reactions:

  • Reductions ( selective one-electron reducing agent)
  • Ring-opening reactions
  • Ring -closure reactions
  • Dimerization
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