Molecular structure of Barium sulfide (CAS NO.21109-95-5) is:

Product Name: Barium sulfide
CAS Registry Number: 21109-95-5
IUPAC Name: sulfanylidenebarium
Molecular Weight: 169.392 [g/mol]
Molecular Formula: BaS
H-Bond Donor: 0
H-Bond Acceptor: 0
EINECS: 256-814-3
Sensitive: Moisture Sensitive
Melting point: 1200°C
Density: 4.25 g/mL at 15 °C(lit.)
Appearance: Colourless crystals, or white to grey-brown powder
Solubility: Insoluble in alcohol
Stable: Stable, but decomposes on heating. Incompatible with acids, oxidizing agents, water
Product categories: Industrial/Fine Chemicals;Catalysis and Inorganic Chemistry;Chalcogenides;Metal and Ceramic Science
SMILES: [Ba+2].[S-2] 
InChI: InChI=1/Ba.S/q+2;-2 
InChIKey: CJDPJFRMHVXWPT-UHFFFAOYAO 
Std. InChI: InChI=1S/Ba.S/q+2;-2 
Std. InChIKey: CJDPJFRMHVXWPT-UHFFFAOYSA-N

 Barium sulfide (CAS NO.21109-95-5) is considered to be the most important synthetic material of barium, the pigment lithopone, ZnS/BaSO₄ and being the precursor to BaCO₃.

 Barium sulfide (CAS NO.21109-95-5) was prepared by Vincentius Casciarolus via a crude version, what is now known as a "carbothermic reduction", employing flour in place of carbon(BaSO₄ is available as the common mineral barite.):
  BaSO₄ + 2 C → BaS + 2 CO₂

Hazard Codes of Barium sulfide (CAS NO.21109-95-5): Xn,Xi ;N
Risk Statements: 20/22-31-50-36/37/38 
R20/22: Harmful by inhalation and if swallowed. 
R31: Contact with acids liberates toxic gas. 
R50: Very toxic to aquatic organisms. 
R36/37/38: Irritating to eyes, respiratory system and skin.
Safety Statements: 28-61 
S28: After contact with skin, wash immediately with plenty of soap-suds. 
S61: Avoid release to the environment. Refer to special instructions / safety data sheets.
RIDADR: UN 2813 4.3/PG 2
WGK Germany: 2
HazardClass: 4.3
PackingGroup: III

 Barium sulfide , its cas register number is 21109-95-5. It also can be called Barium sulfide (BaS) ; Barium sulphide .It is a colourless crystals, or white to grey-brown powder.