Can proton NMR be used to study transition metal complexes?

I prepared metal complexes with a Schiff base ligand L using cobalt(II) chloride hexahydrate, iron(III) chloride hexahydrate, and nickel(II) nitrate hexahydrate. I used 1H NMR to study the difference between them and maybe get some information about the structure of the formed complexes.


The results showed a slight upfield shift in almost every peak and the appearance of some new peaks (attached figure), which is a bit ambiguous for me, and I don't know how to interpret them:


[![enter image description here](https://i.stack.imgur.com/IzSAk.jpg)](https://i.stack.imgur.com/IzSAk.jpg)


