\({\left[ {O \leftarrow \mathop {\mathop {Cr}\limits_ \downarrow ^ \uparrow }\limits_O^O - O - \mathop {\mathop {Cr}\limits_ \downarrow ^ \uparrow }\limits_O^O \to O} \right]^{2 - }}\)
\(6,\) \(Cr - O\) bonds are equivalent.
$\mathrm{H}_2, \mathrm{He}_2^{+}, \mathrm{O}_2^{+}, \mathrm{N}_2^{2-}, \mathrm{O}_2^{2-}, \mathrm{F}_2, \mathrm{Ne}_2^{+}, \mathrm{B}_2$