What is the relation between reduction potential value of metal ion and stability of its complex during chelate formation? Explain with examples

Let us take an example

   Na+   +   e- -------->Na        E=-2.71V

   Cu+2  +  e----------->Cu+     E=+0.34V

This means that sodium does not show greater tendency to get reduced when compared copper.So even in chelate complex formation we have consider the reduction potentials in a similar manner.