Je. Jerome et al., SYNTHESIS OF NEW LOW-DIMENSIONAL QUATERNARY COMPOUNDS, KCU2ASS3 AND KCU4ASS4, IN SUPERCRITICAL AMINE SOLVENT - ALKALI-METAL DERIVATIVES OF SULFOSALTS, Inorganic chemistry, 33(9), 1994, pp. 1733-1734
The reaction of KAsS2, copper powder, and elemental sulfur in supercri
tical ethylenediamine (300-350-degrees-C and 3500 psi) leads to format
ion or two new quaternary solids having the formulas KCu2AsS3 and KCu4
AsS4. Both products are orange crystalline solids having complex low-d
imensional structures of Cu(I) linked by AsS33- groups, forming layers
(for KCu2AsS3) or channels (for KCu4-AsS4). The KCu4AsS4 compound als
o contains lone sulfide ions, which help to cross-link layers. Both so
lids can be considered alkali metal derivatives of sulfosalts.