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. It was first reported in 1838 by Karl Ernst Claus and its structure was determined first in 2018.[2]
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.
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.[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]
Copper(II) thiocyanate, like copper(II) bromide and copper(II) chloride, is a quasi low-dimensional antiferromagnet and it orders at into a conventional Néel ground state.