Question

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

Answer 1

`"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.

Answer 2

Because it is FORMALLY an electron-pair donor.

Explanation:

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