Berkelium(III) chloride also known as berkelium trichloride, is a binary inorganic compound of berkelium and chlorine with the formula BkCl<sub>3</sub>. It is a water-soluble green salt with a melting point of 603 ðC. This compound forms the hexahydrate, BkCl<sub>3</sub>÷6H<sub>2</sub>O.
This compound was first prepared in 1970 by reacting hydrogen chloride gas and berkelium(IV) oxide or berkelium(III) oxide at 520 ðC:
Berkelium(III) chloride reacts with beryllocene to produce berkelocene(Bk(C<sub>5</sub>H<sub>5</sub>)<sub>3</sub>). 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.
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. 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. This hexahydrate consists of BkCl<sub>2</sub>(OH<sub>2</sub>)<sub>6</sub><sup>+</sup> ions and Cl<sup>âÂÂ</sup> ions.
Caesium sodium berkelium chloride is known with the formula Cs<sub>2</sub>NaBkCl<sub>6</sub> and is produced by the reaction of berkelium(III) hydroxide, hydrochloric acid, and caesium chloride.