# What is the name of this compound - MgBr_2?

This is simply $\text{magnesium bromide}$
$M g \left(s\right) + B {r}_{2} \left(l\right) \rightarrow M g B {r}_{2}$...
We formally have $M {g}^{2 +}$ and $B {r}^{-}$ ions...