Berkelium(III) chloride

Berkelium(III) chloride also known as berkelium trichloride, is a binary inorganic compound of berkelium and chlorine with the formula BkCl₃. It is a water-soluble green salt with a melting point of 603 °C. This compound forms the hexahydrate, BkCl₃·6H₂O.

Berkelium(III) chloride

Names
Other names Berkelium trichloride
Identifiers
CAS Number	20063-16-5
3D model (JSmol)	Interactive image
InChI InChI=1S/Bk.3ClH/h;3*1H/p-3 Key: IZRUUNBZXOYLEH-UHFFFAOYSA-K
SMILES [Cl-].[Cl-].[Cl-].[Bk+3]
Properties
Chemical formula	BkCl3
Molar mass	353.36 g/mol
Appearance	Green solid
Melting point	603 °C (1,117 °F; 876 K)[1]
Solubility in water	Soluble
Structure
Crystal structure	Hexagonal
Space group	P63/m
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation and reactions

This compound was first prepared in 1970 by reacting hydrogen chloride gas and berkelium(IV) oxide or berkelium(III) oxide at 520 °C:^[2]

Bk₂O₃ + 6HCl → 2BkCl₃ + 3H₂O

Berkelium(III) chloride reacts with beryllocene to produce berkelocene(Bk(C₅H₅)₃).^[3] It also reacts with oxalic acid to produce berkelium oxalate. This reaction is used to purify this compound, by reacting the oxalate with hydrochloric acid.^[4]

Structure

Anhydrous berkelium(III) chloride has a hexagonal crystal structure, is isostructural to uranium trichloride, and has the person symbol hP6. When heated it its melting point, it converts to an orthorhombic phase.^[2] However, the hexahydrate has a monoclinic crystal structure and is isostructural to americium trichloride hexahydrate with the lattice constants a = 966 pm, b = 654 pm and c = 797 pm.^[5] This hexahydrate consists of BkCl₂(OH₂)₆⁺ ions and Cl⁻ ions.

Complexes

Caesium sodium berkelium chloride is known with the formula Cs₂NaBkCl₆ and is produced by the reaction of berkelium(III) hydroxide, hydrochloric acid, and caesium chloride.^[6]