Copper(II) thiocyanate
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| Name =
| ImageFile = CuNCS2 cropped.png
| ImageSize = 250px
| ImageCaption = Copper(II) thiocyanate
| ImageFile1 = CuNCS2 crystal structure.png
| ImageSize1 = 250px
| ImageCaption1 = Crystal structure of copper(II) thiocyanate
| OtherNames = Cupric thiocyanate
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| Section1 = {{Chembox Identifiers
| CASNo = 15192-76-4
| PubChem = 10103751
| ChemSpiderID = 8279278
| StdInChI=1S/2CHNS.Cu/c2*2-1-3;/h2*3H;/q;;+2/p-2
| StdInChIKey = BQVVSSAWECGTRN-UHFFFAOYSA-L
| SMILES = C(#N)[S-].C(#N)[S-].[Cu+2]
}}
| Section2 = {{Chembox Properties
| Formula = Cu(SCN)2
| Appearance = black powder
| MeltingPt = decomposes at 180 °C
| MagSus = {{val|0.66e-3}} cm3/mol
| Solubility = Insoluble
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| Section7 = {{Chembox Hazards
| ExternalSDS =
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| Section8 = {{Chembox Related
| OtherAnions = Copper(II) bromide, Copper(II) chloride
| OtherCations = Copper(I) thiocyanate, Cobalt(II) thiocyanate, Mercury(II) thiocyanate, Ammonium thiocyanate
Potassium thiocyanate
| OtherCompounds =
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}}Copper(II) thiocyanate (or cupric thiocyanate) is a coordination polymer with formula Cu(SCN)2.{{Cite journal|last1=Cliffe|first1=Matthew J.|last2=Lee|first2=Jeongjae|last3=Paddison|first3=Joseph A. M.|last4=Schott|first4=Sam|last5=Mukherjee|first5=Paromita|last6=Gaultois|first6=Michael W.|last7=Manuel|first7=Pascal|last8=Sirringhaus|first8=Henning|last9=Dutton|first9=Siân E.|last10=Grey|first10=Clare P.|date=2018-04-25|title=Low-dimensional quantum magnetism in Cu(NCS)2: A molecular framework material|journal=Physical Review B|language=en|volume=97|issue=14|pages=144421|doi=10.1103/PhysRevB.97.144421|issn=2469-9950|doi-access=free|arxiv=1710.04889}} It is a black solid which slowly decomposes in moist air. It was first reported in 1838 by Karl Ernst Claus and its structure was determined first in 2018.{{Cite journal|last=Claus|first=C.|date=1838|title=Beiträge zur näheren Kenntniss der Schwefelcyanmetalle|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/prac.18380150142|journal=Journal für Praktische Chemie|language=en|volume=15|issue=1|pages=401–411|doi=10.1002/prac.18380150142|issn=1521-3897|url-access=subscription}}
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.
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.{{Cite journal|last1=Hunter|first1=J. A.|last2=Massie|first2=W. H. S.|last3=Meiklejohn|first3=J.|last4=Reid|first4=J.|date=1969-01-01|title=Thermal rearrangement in copper(II) thiocyanate|url=https://dx.doi.org/10.1016%2F0020-1650%2869%2980226-6|journal=Inorganic and Nuclear Chemistry Letters|volume=5|issue=1|pages=1–4|doi=10.1016/0020-1650(69)80226-6|issn=0020-1650|url-access=subscription}} 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.{{cite journal |last1=Smith |first1=D. L. |last2=Saunders |first2=V. I. |title=Preparation and structure refinement of the 2H polytype of β-copper(I) thiocyanate |journal=Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry |date=15 March 1982 |volume=38 |issue=3 |pages=907–909 |doi=10.1107/S0567740882004361|doi-access=free }}
Magnetism
Copper(II) thiocyanate, like copper(II) bromide and copper(II) chloride, is a quasi low-dimensional antiferromagnet and it orders at {{cvt|12|K|C|0}} into a conventional Néel ground state.