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What is the colour of $\ce{C2N2NiS2}$ (Nickel thiocyanate)?

In most of the web sites it only molecular weight,formula and other specifications but its colour is missing every where.

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  • $\begingroup$ In this paper, it is reported that $\ce{Ni(SCN)2}$ is yellow: link.springer.com/article/10.1007%2FBF00935928 $\endgroup$ – Jannis Andreska Oct 7 '14 at 18:16
  • $\begingroup$ @JannisAndreska Is it anhydrous? Most Ni(II) salts are yellow in anhydrous form and green in hydrate form. $\endgroup$ – t.c Oct 7 '14 at 18:19
  • $\begingroup$ @t.c I think they are referring to the anhydrous salt. $\endgroup$ – Jannis Andreska Oct 7 '14 at 18:21
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After bit research i got finally one link where they mentioned the colour. The other name of(Synonym) of Nickel thiocyanate is "Nickel Thiocyanate Greenpowder" which suggest it is Green in colour.


Reference:ChemicalBook

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The proper answer 'it depends'

PROPERTIES: Formula weight 174.88. Dark chocolate-colored powder. On addition of water, becomes first yellow and then dissolves with a green color.

(c) Brauer

In general you should be extremely cautious guessing colors of $d$-metal salts when the metal ion is not hydrated. The color may range widely. The only reasonably safe assumption is that $d^0$-salts are usually colorless, but then agains $\ce{MnO4-}$ is violet, so the colors must be memorized separately for each case.

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It's a kind of a yellow/green brown, assuming you mean the solid. Aqueous (and similar solvents) solutions are green. c.f. Dubler, E., Relier, A., & Oswald, H. R. (1982). Intermediates in thermal decomposition of nickel (II) complexes: The crystal structures of Ni (SCN) 2 (NH3) 2 and Ni (SCN) 2. Zeitschrift für Kristallographie-Crystalline Materials, 161(1-4), 265-278.

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Most hydrated Ni(II) salts are green.

For transition metals, its salts are often colored because of transitions of electrons between d-orbitals of different energy, and such transitions release protons of a specific wavelength (which happen to be within the visible range of light for most d block elements).

Therefore, for a transition metal with the same oxidation state, its hydrated salts often exhibit a characteristic color. In fact for most transition metal salts, the color can be predicted simply by knowing the cation of the salt.

http://en.wikipedia.org/wiki/Color_of_chemicals#Ions_in_aqueous_solution

For example, Cu(II) salts are blue, Ni(II) salts are green.

As thiocyanate has the charge of -1, the nickel in $\ce{Ni(SCN)2}$ has the charge of +2, and $\ce{Ni(SCN)2}$ is therefore green, as confirmed in the answer given by @hey.

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