Nickel selenide

Stoichiometric NiSe:   Ni   Se
Names
IUPAC name Nickel(II) selenide
Other names Nickel selenide
Identifiers
CAS Number	1314-05-2 Y
ChemSpider	56182
ECHA InfoCard	100.013.834
EC Number	215-216-2
PubChem CID	62394
UNII	KB76MY8R90 Y
CompTox Dashboard (EPA)	DTXSID00157023
Properties
Chemical formula	NiSe
Molar mass	137.65 g/mol
Appearance	black powder
Density	7.2 g/cm3
Solubility in water	Insoluble
Hazards
Safety data sheet (SDS)	[]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Nickel selenide is the inorganic compound with the formula NiSe. As for many metal chalcogenides, the phase diagram for nickel(II) selenide is complicated. Two other selenides of nickel are known, NiSe₂ with a pyrite structure, and Ni₂Se₃. Additionally, NiSe is usually nonstoichiometric and is often described with the formula Ni_1−xSe, with 0 < x < 0.15.^[1] This material is a semi-conducting solid, and can be obtained as in the form of a black fine powder, or silver if obtained in the form of larger crystals. Nickel(II) selenide is insoluble in all solvents, but can be degraded by strongly oxidizing acids.

Synthesis and structure

Typically, NiSe is prepared by high temperature reaction of the elements. Such reactions typically afford mixed phase products. Milder methods have also been described using more specialised techniques such as reactions of the elements in liquid ammonia in a pressure vessel.^[2]

Like many related materials, nickel(II) selenide adopts the nickel arsenide motif. In this structure, nickel is octahedral and the selenides are in trigonal prismatic sites.^[3]