EDTA-Magnesium relationship

[ChenHA]

" J. Martinez-Irujo" wrote:
> 
> I agree with Tim Fitzwater in that a single cation is bound per EDTA
> molecule. The matter is not how many charges EDTA has, but what makes EDTA
> so efficient in chelating cations. EDTA behaves like an octopus: each
> nitrogen forms a dative bond with the cation and oxygens from the carboxylic
> groups forms additional coordination bonds. As a result, the cation remains
> tightly bound at the center of the structure (and only a cation can be bound
> in this way).
> 

If anyone is interested, here's a picture of EDTA chelating
a metal ion using its six binding sites:

http://www.chem.neu.edu/Courses/1221Tom/99Lecture15/sld003.htm