what ions form na2+?

Answer 1

The only compound that I know that presents this form is:

NaO2 - sodium superoxide, but in this case is Oxygen that works with oxidation number (-1) and Sodium remains with oxidation number (1+) this kind of compunds has the form:

O - O - Na

Other similar is Na2O2 - Sodium Peroxide but sodium still remains with oxidation number (1+):

Na - O - O - Na