Ligands and lowering reduction potential

Chickenpoxpie

Hi I have a question I was wondering if y'all could clear up. Lets say I have two metal cations, Iron (III) and Manganese (II). Will binding them to an anionic ligand lower their reduction potentials (making each a better redundant) and if so why?

Is it because the anionic charge of the ligand stabilizes the positive charge of the metals?

What if the ligand binds with a high coordination number (say 5 or 6). Will that further reduce the reduction potential because now the entire complex has a negative charge and is better able to donate electrons (ie good reluctant)?

Borek

Basically it is about the concentration of the free metal. You can safely assume what is happening is that it is free metal that reacts, and ligands just change its concentration. Once you know the concentration, it is just a matter of applying Nernst equation.

chemisttree

Yes, that's exactly how it works. Read up on Cytochrome p450 and you will see this effect in action.