Question

Which of the following reactions does not take place?
$B{F}_3+F^{-}⟶B{F}_4^{-}.....$(I)
$B{F}_3+3F^{-}⟶B{F}_6^{3-}......$(II)
$Al{F}_3+3F^{-}⟶Al{F}_6^{3-}.....$(III)

• A. Only (I)
• B. Only (II)
• C. Only (III)
• D. Only (I) and (III)

Answer 1

Answer: (B)

$B{F}_3$ forms complex halides of the type $\left[B{F}_4^{-}\right]$in which $B$ atom has C.N. 4, it cannot extend its C.N. beyond $4$ due to the nonavailability of $d$-orbitals in its configuration. Hence, $B{F}^3{}_6$ ion ( $s{p}^3{d}^2$ hybridisation) is not formed. On the other hand, Al can extend its C.N. beyond 4 due to the availability of d-orbitals in its configuration.