Nickel(II) bromide

Nickel(II) bromide is the name for the inorganic compounds with the chemical formula NiBr₂(H₂O)_x. The value of x can be 0 for the anhydrous material, as well as 2, 3, or 6 for the three known hydrate forms. The anhydrous material is a yellow-brown solid which dissolves in water to give blue-green hexahydrate (see picture).

Nickel(II) bromide

Anhydrous
Hexahydrate
Names
IUPAC name Nickel(II) bromide
Other names Nickel dibromide, Nickel bromide, Nickelous bromide
Identifiers
CAS Number	13462-88-9 Anhydrous Y 13596-19-5 dihydrate N 7789-49-3 trihydrate N 18721-96-5 hexahydrate N
3D model (JSmol)	Interactive image
ChemSpider	24251 N
ECHA InfoCard	100.033.318
EC Number	236-665-0
PubChem CID	278492
UNII	41SGH8A2S6 Y
UN number	3288 (NICKEL BROMIDE)
CompTox Dashboard (EPA)	DTXSID40928693
InChI InChI=1S/2BrH.Ni/h2*1H;/q;;+2/p-2 N Key: IPLJNQFXJUCRNH-UHFFFAOYSA-L N
SMILES [Ni+2].[Br-].[Br-]
Properties
Chemical formula	NiBr2
Molar mass	218.53 g/mol
Appearance	yellow-brown crystals
Odor	odorless
Density	5.10 g/cm3[1]
Melting point	963 °C (1,765 °F; 1,236 K) sublimes[1]
Solubility in water	1.13 kg/L (0 °C) 1.22 kg/L (10 °C) 1.31 kg/L (20 °C)[1] 1.44 kg/L (40 °C) 1.55 kg/L (100 °C)[2]
Band gap	2.5 eV[3]
Magnetic susceptibility (χ)	+5600.0·10−6 cm3/mol[4]
Structure[5]
Crystal structure	hexagonal, hR9
Space group	R3m, No. 166
Lattice constant	a = 0.36998 nm, c = 1.82796 nm
Formula units (Z)	3
Thermochemistry[6]
Std enthalpy of formation (ΔfH⦵298)	−212.1 kJ·mol−1
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Irritant, corrosive
NFPA 704 (fire diamond)	1 0 0
Flash point	Non-flammable
Related compounds
Other anions	nickel(II) fluoride nickel(II) chloride nickel(II) iodide
Other cations	cobalt(II) bromide copper(II) bromide palladium(II) bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Structure

The structure of the nickel bromides varies with the degree of hydration. In all of these cases, the nickel(II) ion adopts an octahedral molecular geometry. Similar structures are observed in aqueous solutions of nickel bromide.^[7]

• Anhydrous NiBr₂ adopts the hexagonal cadmium chloride structure.^[8] The interatomic distance for Ni-Br is 2.52—2.58 Å.^[7] Anhydrous NiBr₂ is a paramagnet at room temperature. Upon cooling, it turns into an antiferromagnet at 52 K, and then into a helimagnet at 22.8 K.^[5]
• The structure of the trihydrate has not been confirmed by X-ray crystallography. It is assumed to adopt a chain structure.^[9]
• The di- and hexahydrates adopt structures akin to those for the corresponding chlorides. The dihydrate consists of a linear chain, whereas the hexahydrate features isolated trans-[NiBr₂(H₂O)₄] molecules together with two water molecules of crystallization.

Reactions and uses

NiBr₂ has Lewis acid character, as indicated by its tendency to hydrate and form adducts with a variety of other Lewis bases.

NiBr₂ is also used to prepare catalysts for cross-coupling reactions and various carbonylations.^[8] NiBr₂-glyme shows increased activity compared to NiCl₂-glyme for some transformations.^[10]

NiBr₂-catalyzed cross-coupling reaction

Safety

This compound is a suspected carcinogen.^[11]