Question

write a limitation of HSAB principle​

Answer 1

Explanation:

However, it occurs because the stronger, soft-base SO32- displaced the weaker, hared base F- form the hard acid H+. Similarly , a very strong hard base OH- can displace a less strong soft base, SO32- form the soft acid CH3Hg+ .

Answer 2

Answer:

HSAB theory is in direct contradiction with Fajan's rules. For example, the later predict the nature of Beryllium salts to be more covalent. But according to the HSAB principle, the Be2+ ion is hard acid and is expected to show charge controlled bonding that results in more ionic nature for beryllium compounds. But this is not true.

Since hydrogen ion, H+ is a hard acid and hydride ion, H- is a soft base, according to HSAB principle the interactions between them must be polar covalent and H2 must be unstable. Indeed H2 is a stable molecule with pure covalent nature.