Question

Why does backbonding occur in boron halides and not in aluminum halides?

Answer 1

Dear Student,
Answer to your question is given below:

The pπ-pπ back bonding is linked with the size of the central atom in the halide and decreases with the increase in size. Since the size of aluminium is quite big as compared to that of boron. pπ-pπ back bonding is possible in boron and not in aluminium. In boron halides boron is sp2 hybridised. The remaining unhybridized p orbital is empty and as such it can electrons by overlapping with a filled p orbital of the halogen atom. The remaining unhybridized p orbital is empty and as such it can electrons by overlapping with a filled p orbital of the halogen atom. Therefore, back bonding occurs in boron halides and not in aluminium halides

Regards,