Question

compare the lewis acidic strength in the following molecules

BF3 , BCl3 , BBr3, BI3​

Answer 1

↪️Lewis Acidic strength ↩️

Order of acidic strength of gievn molecules is :-

BF3 < BCl3 < BBr3 < BI3

✧ The extent of back bonding is F>>cl>Br>I because F is element of 2nd period.

✧ Inter electronic repulsion is maximum for fluorine.

✧ The nature of pi bonds are respectively 2Pπ - 2Pπ , 2Pπ - 3Pπ , 2Pπ - 4Pπ and 2Pπ - 5Pπ.

✧ Hence as much extent of back bonding is more electron deficiency of boron atom decreases more by which lewis acidic strength decreases.