Molecule structure of Nickel dinitrite (CAS NO.17861-62-0):

IUPAC Name: Nickel; nitrous acid 
Molecular Weight: 105.70684 g/mol
Molecular Formula: HNNiO₂
H-Bond Donor: 1
H-Bond Acceptor: 3
Exact Mass: 104.936076
MonoIsotopic Mass: 104.936076
Topological Polar Surface Area: 49.7
Heavy Atom Count: 4
Complexity: 10.3
Canonical SMILES: N(=O)O.[Ni]
InChI: InChI=1S/HNO2.Ni/c2-1-3;/h(H,2,3);
InChIKey: SMCYUGZOESLMKM-UHFFFAOYSA-N

 Nickel dinitrite is used to make other chemicals.

NTP 10th Report on Carcinogens.

RIDADR: 2726
HazardClass: 5.1
PackingGroup: III
Confirmed carcinogen. When heated to decomposition it emits toxic fumes of NO_x and Ni.

OSHA PEL: TWA 1 mg(Ni)/m³
ACGIH TLV: TWA 0.05 mg(Ni)/m³; Confirmed Carcinogen
DOT Classification:  5.1; Label: Oxidizer

 Nickel dinitrite (CAS NO.17861-62-0) is also named as Nitrous acid, nickel (2+) salt ; Nickel nitrite [UN2726] [Oxidizer] ; UN2726 . Nickel dinitrite (CAS NO.17861-62-0) is a crystalline solid or the solid dissolved in a liquid. It is slightly soluble in water. Contact may irritate skin, eyes and mucous membranes. It may be toxic by ingestion. Nickel dinitrite is noncombustible, but accelerates the burning of combustible materials. Nickel dinitrite is a strong oxidizing agent. A violent explosion occurs if an ammonium salt is melted with a nitrite salt. A mixture of potassium cyanide and nitrite salts may cause an explosion. Inhalation, ingestion or contact (skin, eyes) with vapors or substance may cause severe injury, burns or death. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause pollution. These substances will accelerate burning when involved in a fire. Some may decompose explosively when heated or involved in a fire. May explode from heat or contamination. Some will react explosively with hydrocarbons (fuels). May ignite combustibles (wood, paper, oil, clothing, etc.). Containers may explode when heated. Runoff may create fire or explosion hazard.