Nickel complexes, lability coordinated water

The Variation of the Lability of Coordinated Water in Nickel(II) Complexes... 

It is clear from Table I that there is no evidence that a 1- or 2- complex loses its coordinated water at a faster rate than a 1+ or 2+ complex. In fact, the [Nidien] complex is much more labile to NH substitution than are the negatively charged complexes of nickel. It is also not true that the binding strength of a ligand in the inner coordination sphere of a metal ion depends necessarily on its overall charge (cf. SO as compared to H O (1)). 

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