Germanium monosulfide or Germanium(II) sulfide is the chemical compound with the formula GeS. It is a chalcogenide glass and a semiconductor.[1] Germanium sulfide is described as a red-brown powder or black crystals. Germanium(II) sulfide when dry is stable in air, hydrolyzes slowly in moist air but rapidly reacts in water forming Ge(OH)2 and then GeO.[2] It is one of a few sulfides that can be sublimed under vacuum without decomposition.[3]
First made by Winkler by reducing GeS2 with Ge. Other methods include reduction in a stream of H2 gas, or with an excess of H3PO2 followed by vacuum sublimation.
It has a layer structure similar to that of black phosphorus. The Ge-S distances range from 247 to 300 pm. Molecular GeS in the gas phase has a Ge-S bond length of 201.21 pm.