Why is #AlCl_3# an electrophile?

1 Answer
May 13, 2016

Because the aluminum centre is electron deficient and tends to accept electron density.

Explanation:

We write #AlCl_3#, but its actual structure is #{Cl_2Al}_2(mu-Cl)_2#, i.e. dimeric #Al_2Cl_6#; the aluminum centre is electron deficient and drafts in available electron density to satisfy its Lewis-acidity. Much of the chemistry of aluminum may be rationalized on the basis of completing its octet.

Of course aluminum forms such ions as #AlCl_4^-#, tetrachloroaluminate, and #AlH_4^-#, aluminum hydride.