Aqueous Ni II - bromo complexes

The available quantitative information on the formation of NiBr, according to Reaction (V.73), is collected in Table V-13. 

There are large differences between the values listed in Table V-13. This is the consequence of the inherent difficulties that occur when formation constants of weak complexes are determined (see also Sections V.4.2.1 and V.4.2.4). The values reported in [63NET/DRO], [70MIR/MAK] and [73HUT/HIG] are of low precision, due to a considerable medium effect. The semi-thermodynamic formation constant reported in [90BJE] probably gives an exact description of complex formation in 3.5 - 11 M LiBr, 

The formation of the dibromo complex NiBr2(aq) is dominant only at very high bromide concentrations (8 - 12 M LiBr or HBr). Therefore, only semi-thermodynamic stability constants (log K ) are available for this species. The reported values are as 

The higher value reported in [90BJE] is reasonable when the very low water activity in concentrated LiBr or HBr solutions is taken into account. 

Two quantitative results are available for the enthalpy of Reaction (V.73) (Table V-14). The lack of experimental details and some unidentified experimental errors (see Appendix A), however, do not allow selection of accepted values for A.//JV.73). 

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