In which of the following pairs of molecules/ions both the species are not likely to exist?

$H_2^{2+}$ =  $\underset{1s^0}{\overset{ }{\sigma }}$$\underset{1s^0}{\overset{\ast }{\sigma }}$   
Bond order for $\frac{1}{2}$ =  $\frac{1}{2}$ ( 0 – 0 ) = 0
  He2=  $\underset{1s^2}{\overset{ }{\sigma }}$$\underset{1s^2}{\overset{\ast }{\sigma }}$     
Bond order for He2 =  $\frac{1}{2}$ ( 2 – 2 ) = 0
so both $H_2^{2+}$  and  He2 do not exist