What are the possible resonance structures for $\ce{ClO_2^-}$? Assigning one double bond to the structure makes for formal charges of $\ce{O (-1) - Cl (0) = O (0) <-> O (-1) = Cl (0) - O (-1)}$. It appears that the same set of formal charges can be achieved with two double bonds (expanding the octet on $\ce{Cl}$ to 12 electron capacity, using the d orbital). That is, $\ce{O (0) = Cl (-1) = O (0)}$.

Is this feasible, and if not, why not?

What are the possible resonance structures for $\ce{ClO_2^-}$? Assigning one double bond to the structure makes for formal charges of $\ce{O(-1)-Cl(0)=O(0) <-> O(-1)=Cl(0)-O(-1)}$. It appears that the same set of formal charges can be achieved with two double bonds (expanding the octet on $\ce{Cl}$ to 12 electron capacity, using the d orbital). That is, $\ce{O(0)=Cl(-1)=O(0)}$.

Is this feasible, and if not, why not?

What are the possible resonance structures for ${ClO_2}^{-}$? Assigning one double bond to the structure makes for formal charges of O (-1) - Cl (0) = O (0) $\leftrightarrow$ O (-1) = Cl (0) - O (-1). It appears that the same set of formal charges can be achieved with two double bonds (expanding the octet on Cl to 12 electron capacity, using the d orbital). That is, O (0) = Cl (-1) = O (0).

Is this feasible, and if not, why not?

What are the possible resonance structures for $\ce{ClO_2^-}$? Assigning one double bond to the structure makes for formal charges of $\ce{O (-1) - Cl (0) = O (0) <-> O (-1) = Cl (0) - O (-1)}$. It appears that the same set of formal charges can be achieved with two double bonds (expanding the octet on $\ce{Cl}$ to 12 electron capacity, using the d orbital). That is, $\ce{O (0) = Cl (-1) = O (0)}$.

Is this feasible, and if not, why not?