# Lewis acid character

Which will have more lewis acid character out of $$\ce{BCl3}$$ and $$\ce{AlCl3}$$ ?

My attempt: In $$\ce{BCl3}$$, the back bonding takes place and there is 3pπ-2pπ overlap and in $$\ce{AlCl3}$$ it is 3pπ-3dπ overlap which is less effective than the first. So Al is more electron deficient as compared to B hence $$\ce{AlCl3}$$ must have higher lewis acid character but answer is its reverse. Please tell me where I'm wrong.

Most lone pair donors are from the 2nd or 3rd periods in the Periodic Table, as such the $$\pi$$ overlap with boron will be stronger than that in aluminium.