We do a lot of Nickel complex chemistry. For this we already prepared some reactants. One is the commercial green Nickel(II)Chloride Hexahydrate which is shown at the beginning of the video. We dried this to make the anhydrous yellow Nickel(II)Chloride as well. If weak Ni(2+) solutions are required we also have a Nickel(II)Chloride solution (as it takes some while for the NiCl2 to dissolve in water).

The question is, how would the solution look like if we added some of the anhydrous yellow powder to conc. HCl ? We already showed this for Cobalt and Copper. So we expect a yellow solution here. For comparison we left the aqua complex next to the vial containing the anhydrous NiCl2 and added the acid.

A yellow solution formed. This contains the tetrahedrally coordinated [NiCl4](2-) which is also the third coordination shape for Nickel.
The green Aqua complex is an octahedron and the orange [Ni(CN)4](2-) complex was square planar.

Another way to show this would be to dissolve it in Ethanol. Now some literature suggests that ethanolic solutions of anhydrous d-Metal Chlorides for example contain the pure [MClx](y-) but other books mention that Ethanol can indeed act as ligand as well.

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