Nickel formate Green crystals; soluble in water; used as a hydrogenation catalyst. [synonyms] Nickel(ii) formate dihydrate, formic acid nickel(2+) salt, nickel diformate dihydrate. [properties] Compound formula: c2h6nio6 Molecular weight: 184.76 Appearance: green crystals Melting point: 130-140 â°c Density: 2.15 g/cm3 Nickel(ii) formate dihydrate is one of numerous organometallic compounds . Organometallics are useful reagent, catalyst, and precursor materials with applications in thin film deposition, industrial chemistry, pharmaceuticals, led manufacturing, and others