Aluminium Chloride (AlCl3)

In aluminium chloride, AlCl3, the aluminium atom is likewise sp2 hybridised with one vacant, unhybridised p-orbital, exactly analogous to boron in BCl3. However, aluminium (unlike boron) has empty 3d orbitals available in its valence shell, and these let a chlorine atom's lone pair coordinate into the empty orbital on a neighbouring AlCl3 unit. As a result, AlCl3 does not usually exist as simple monomeric molecules but dimerises into Al2Cl6, in which two aluminium centres are bridged by two chlorine atoms, each bridging chlorine dona …