# Why is "C"l^- a Lewis base?

May 22, 2018

$\text{C} {l}^{-}$ is a Lewis base because it donates a nonbonding electron pair.

#### Explanation:

An example of this is "Co"("NH"_3)_4("C"l)_2^(2+). It is a complex ion were chlorine has donated electron pairs to cobalt.

May 22, 2018

Because it is FORMALLY an electron-pair donor.

#### Explanation:

And of course it is a fairly poor Lewis-base. Its conjugate acid $H C l$ is a strong ”Bronsted acid”. Fluoride anion is a stronger Lewis-base. Why should this be so?