The reaction of K2Se5 and Cu yields single crystal of potassium tetracopper
triselenide, KCu4Se3, which is isotypic with the sulfides ACu(4)S(3) (A =
K, R Cs, Tl) and the selenide CsCu4Se3. The structure consists of double la
yers of copper cations, tetrahedrally coordinated by selenium and separated
by potassium cations.