Protactinium(IV) chloride

Names
IUPAC name Protactinium(IV) chloride
Identifiers
CAS Number	13867-41-9 Y
3D model (JSmol)	Interactive image
InChI InChI=1S/4ClH.Pa/h4*1H;/q;;;;+4/p-4 Key: YVRMMEYNJWFJEX-UHFFFAOYSA-J
SMILES [Pa](Cl)(Cl)(Cl)Cl
Properties
Chemical formula	PaCl4
Molar mass	372.848 g mol−1
Appearance	chartreuse
Density	4.72 g/cm3
Structure
Crystal structure	tetragonal[1]，tI20
Space group	I41/amd , No. 141
Related compounds
Other anions	Protactinium(IV) fluoride Protactinium(IV) bromide Protactinium(IV) iodide
Other cations	Uranium(IV) chloride Thorium(IV) chloride Praseodymium(III) chloride
Related compounds	Protactinium(V) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Protactinium(IV) chloride is an inorganic compound. It is an actinide halide, a salt composed of protactinium and chlorine. It is radioactive, and has the chemical formula of PaCl₄. It is a chartreuse-coloured (yellowish-green) crystal^[1] of the tetragonal crystal system.

Protactinium(IV) chloride can be prepared by the reduction of protactinium(V) chloride:^[2]

${\displaystyle {\ce {2 PaCl5 + H2 -> 2 PaCl4 + 2 HCl))}$

${\displaystyle {\ce {3 PaCl5 + Al -> 3 PaCl4 + AlCl3))}$

It can also be obtained by the chlorination of protactinium(IV) oxide:^[2]

${\displaystyle {\ce {PaO2 + 2 CCl4 -> PaCl4 + 2 COCl2))}$

It can also be formed during the thermal decomposition of protactinium oxychloride at 500 °C in a vacuum:^[3]

${\displaystyle {\ce {2 PaOCl2 -> PaCl4 + PaO2))}$

Protactinium(IV) chloride is a chartreuse, hygroscopic, crystalline solid that can be sublimed at 400 °C in a vacuum. It is soluble in strong mineral acids, forming green solutions. The complex PaCl₄·4CH₃CN is formed with acetonitrile. It has a tetragonal crystal structure with the space group I4₁/amd (space group no. 141) and the lattice parameters a = 837.7 pm, c = 747.9 pm^[2] of the uranium(IV) chloride type.^[4]