Copper(II) thiocyanate

Copper(II) thiocyanate (or cupric thiocyanate) is a coordination polymer with formula Cu(SCN)₂.^[1] It is a black solid which slowly decomposes in moist air.^[2] It was first reported in 1838 by Karl Ernst Claus and its structure was determined first in 2018.^[3][1]

Copper(II) thiocyanate

Copper(II) thiocyanate
Crystal structure of copper(II) thiocyanate
Names
Other names Cupric thiocyanate
Identifiers
CAS Number	15192-76-4
3D model (JSmol)	Interactive image
ChemSpider	8279278
PubChem CID	10103751
CompTox Dashboard (EPA)	DTXSID001337084
InChI InChI=1S/2CHNS.Cu/c2*2-1-3;/h2*3H;/q;;+2/p-2 Key: BQVVSSAWECGTRN-UHFFFAOYSA-L
SMILES C(#N)[S-].C(#N)[S-].[Cu+2]
Properties
Chemical formula	Cu(SCN)2
Molar mass	179.71 g/mol[1]
Appearance	black powder
Density	2.47 g/cm3[1]
Melting point	decomposes at 180 °C[2]
Solubility in water	Insoluble
Magnetic susceptibility (χ)	0.66×10−3 cm3/mol[1]
Related compounds
Other anions	Copper(II) bromide, Copper(II) chloride
Other cations	Copper(I) thiocyanate, Cobalt(II) thiocyanate, Mercury(II) thiocyanate, Ammonium thiocyanate Potassium thiocyanate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Structure

The structure of Cu(SCN)₂ was determined via powder X-ray diffraction and consists of chains of Cu(NCS)₂ linked together by weak Cu–S–Cu bonds into two-dimensional layers. It can be considered a Jahn–Teller distorted analogue of the mercury thiocyanate structure-type. Each copper is octahedrally coordinated by four sulfurs and two nitrogens. The sulfur end of the SCN⁻ ligand is doubly bridging.^[1]

Synthesis

Copper(II) thiocyanate can be prepared from the reaction of concentrated solutions of copper(II) and a soluble thiocyanate salt in water, precipitating as a black powder.^[2][3] With rapid drying, pure Cu(SCN)₂ can be isolated. Reaction at lower concentrations and for longer periods of time generates instead copper(I) thiocyanate.^[4]

Magnetism

Copper(II) thiocyanate, like copper(II) bromide and copper(II) chloride, is a quasi low-dimensional antiferromagnet and it orders at 12 K (−261 °C) into a conventional Néel ground state.^[1]