Structure and Properties
NiCl2 adopts the CdCl2 structure. In this motif, each Ni2+ center is coordinated to six Cl- centers, and each chloride is bonded to three Ni(II) centers. In NiCl2 the Ni-Cl bonds have "ionic character". Yellow NiBr2 and black NiI2 adopt similar structures, but with a different packing of the halides, adopting the CdI2 motif.
In contrast, NiCl2ยท6H2O consists of separated trans- molecules linked more weakly to adjacent water molecules. Note that only four of the six water molecules in the formula are bound to the nickel, and the remaining two are water of crystallisation. Cobalt(II) chloride hexahydrate has a similar structure.
Many nickel(II) compounds are paramagnetic, due to the presence of two unpaired electrons on each metal center. Square planar nickel complexes are, however, diamagnetic.
Nickel(II) chloride solutions are acidic, with a pH of around 4 due to the hydrolysis of the Ni2+ ion.
Read more about this topic: Nickel(II) Chloride
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