Uranium(III) chloride
Hexagonal
A = 745.2 pm c = 432.8 pm
U, Cl
Urantrichlorid
Red crystals
Fixed
5.50 g · cm -3
837 ° C
1657 ° C
Risk
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Uranium ( III) chloride is a chemical compound consisting of the elements uranium and chlorine. It has the formula UCl3 and belongs to the class of chlorides. It is an intermediate in the reprocessing of spent nuclear fuel.
Representation
There are two routes for the synthesis of uranium ( III) chloride. Firstly, it can be obtained at 670-710 ° C by the reaction of uranium metal in a salt melt of sodium chloride and potassium chloride.
Another way, by heating of uranium ( IV) chloride under a hydrogen atmosphere.
Properties
At room temperature uranium (III ) chloride is a red, very hygroscopic crystalline solid which is very soluble in water. UCl3 has a lower stability than uranium (IV ) chloride ( UCl4 ), since the oxidation state 3 is stabilized in an acid solution. In hydrochloric acid solution UCl3 has a higher stability than in water. Uranium (III) - chloride melts at 837 ° C and boils at 1657 ° C, it has a density of 5.50 g/cm3.
Three hydrates of the uranium (III ) chloride are known:
- UCl3 · 2 H2O · 2 CH3CN
- UCl3 · 6 H2O
- UCl3 · 7 H2O
They are prepared by reduction of uranium (IV ) chloride in acetonitrile in the presence of water and propionic acid.
Crystal structure
The structure of uranium (III ) chloride is the lead for a number of other compounds. In this, the uranium atoms are surrounded by nine chlorine atoms. As coordination polyhedra there arises a triple überkapptes, trigonal prism, as it is frequently found even in the later actinides and lanthanides. It crystallizes in the hexagonal crystal system, space group P63 / m with lattice parameters a = 745 pm and c = 433 pm and two formula units per unit cell. Further compounds which crystallize in a uranium ( III) chloride structure include neptunium (III ) chloride, plutonium (III ) chloride, americium (III ) chloride, curium (III ) chloride and antimony (III) - chloride.
Use
Uranium ( III) chloride is used for displaying various Uranmetallocene, for example, in reactions with tetrahydrofuran (THF) and Methylcyclopentadienylnatrium. It can also use as a catalyst, see for example the case of reactions between lithium aluminum hydride ( LiAlH4 ) and alkenes for the synthesis of alkyl aluminum compounds.
Uranium (III ) chloride is used in salt melts and plays a role in the reprocessing of spent nuclear fuel.
Safety
Similar to other soluble uranium compounds UCl3 is easily absorbed. It is highly toxic by inhalation and if swallowed. There is also the risk of accumulation in the human body, which affects mainly the liver and kidneys. For aquatic organisms, it is also toxic and may cause long term adverse effects in the aquatic world. As all the uranium compounds it is radioactive. The activity is dependent upon the isotope composition of the uranium.