Question

The geometry and the number of unpaired electron(s) of $[MnB{r}_4{]}^{2-}$, respectively, are

• A. tetrahedral and 1
• B. square planar and 1
• C. tetrahedral and 5
• D. square planar and 5

Answer 1

Answer: (C)

The oxidation state of $Mn$ in $[MnB{r}_4{]}^{-2}$ is $+2$ .
The electronic configuration of $M{n}^{2+}$ is $[Ar]3d_{5}4s_0$

As, $B{r}^{-}$ is a weak field ligand pairing of electron will not occur

As, the hybridisation of $Mn$ in $[MnB{r}_4{]}^{2-}$ is $s{p}^3$, thus its geometry will be tetrahedral and it contains five unpaired electrons.