Question

The exhibition of the highest co-ordination number depends on the availability of vacant orbitals in the central atom. Which of the following elements is not likely to act as a central atom in $M{F}_6^{3-}$?

• A. $B$
• B. $Al$
• C. $Ga$
• D. $In$

Answer 1

The correct option is A $B$

The element $M$ in the complex ion ${M{F}_6}^{3-}$ has a coordination number of six. Since boron has only s and p-orbitals and no d-orbitals, therefore, boron is restricted to a maximum covalence of four (using 2s and three 2p orbitals). Thus, $B$ cannot form a complex of the type ${M{F}_6}^{3-}$.