Why does AlCl3 undergo dimerization?

AlCl3 exists as a dimer as the Al atom in the molecule is electron deficient due to presence of only 6 electrons in its’ valence shell ie it has an incomplete octet due to which it is quite unstable. The dimer so formed (Al2Cl6) is more stable and undergoes milder reactions than the monomer AlCl3.

Why BCl3 does not form dimer?

Thus, the electron deficiency of BCl3 is compensated by formation of pπ–pπ bonds within the molecule so no dimer forms.

Can BCl3 form dimer?

AlCl3 forms a dimer but BCl3 does not form dimer.

Why boron halides do not exist as dimers while AlCl3 exists as al2cl3?

Boron atom being small in size is unable to accommodate large sized halogens around it. While in AlCl3, Al atom has large size. They make use of vacant p-orbitals by coordinate bond i.e., metal atoms complete their octet by forming dimers, Al2Cl6.

Why AlCl3 do not show back bonding?

Back bonding occurs between the same size of orbitals of small atoms. 3p orbitals of Al and Cl are comparatively larger. So, back bonding doesn’t occur in AlCl3.

Why BH3 exist but not BCl3?

BCl3 does not exist as a dimer, but BH3 exists as dimer B2H6 because, large-sized chlorine atoms do not fit between the small boron atoms, whereas small-sized hydrogen atoms get held in between boron atoms. Because of its instability, it exists as a dimer, B2H6, where electrons are shared between the monomers.

Why boron does not form dimer?

$B{F_3}$ does not form a dimer because boron is small in size and cannot accommodate more fluorine atoms therefore it cannot form a dimer .

Why Aluminium halides exist as dimers but boron halides exist as monomers?

Answer:Both boron and aluminum halides are lewis acids but only aluminum halides exist as dimer because due to small size of boron, it cannot accommodate four large sized halogen around it.

Why do boron halides do not Dimerize where as the rest of the element in the same group Dimerize?

Boron halides do not exist as dimer due to small size of boron atom which makes it unable to coordinate four large‐sized halide ions.

Why is there no back bonding in BCl3?

In BCl3 , the 3p orbitals on Cl are bigger than the 2p orbital on B , so orbital overlap is less efficient, and backbonding is less important.