  We report the discovery of KxFe2-yS2 single crystals, isostructural to
KxFe2-ySe2 superconductors. The sulfide compound is a small gap semiconductor
and shows spin-glass behavior below 32 K. Our results indicate that
stoichiometry, defects, and the local environment of FeCh (Ch = S,Se)
tetrahedra have important effects on the physical properties of isostructural
and isoelectronic KxFe2-yCh2 compounds.
