The crystal unit of the solid hexahydrate •6 contains the neutral molecule trans- and two molecules of water of crystallization. This species dissolves readily in water and alcohol.
The anhydrous salt is hygroscopic and the hexahydrate is deliquescent. The dihydrate, CoCl(HO), is a coordination polymer.  Each Co center is coordinated to four doubly bridging chloride ligands.  The octahedron is completed by a pair of mutually trans aquo ligands.