[zeoblade]

The CoCl₂▫6H₂O solution is deep violet in ethanol but deep red as the solid and pale red as the solution.

I'm wondering when in aqueous solution, the aqua species confer the pale red colour but in ethanol there are no water ligands to bite the Co(II). So when added to water the deep blue colour is formed is due to chains of edge Co-Cl₂-Co sharing ligands in a square planar arrangement and water ligands occupying the remaining sites? Or is it a cis-trans circumstance that gives the difference in colour? Because if it is cis-trans issue, I don't understand how excess water can cause this.