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Whichever substrate has more electron deficiency at B must be stronger Lewis acid.
Since both boron and fluorine are in second period of periodic table that's why they have p orbitals of the same sizes .
Thus 2p orbitals of fluorine overlap with the empty orbitals of boron by donating it's electron pair. This is called back bonding.
Back bonding in BCl3 is not likely as in case of BF3 because of the difference in size of p orbitals of Boron and Chlorine.
Due to back bonding the boron of BF3 becomes less electron demanding and thus BCl3 is the better Lewis acid here.
:)
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What ever has more electron deficiency at Boran center must be better electron acceptor,hence better Lewis acid,isn’t it?
Now both B and F are in second period of periodic table,so have comparable sizes ,so also p orbitals of similar dimensions
so the filled 2p orbitals of F overlap with those of empty orbitals of B in what is called as back bonding
Since back bonding makes B of BF3 less electron demanding than that of BCl3
Obviously BCl3 is better Lewis acid than BF3
Have recognised that difference in sizes of 3p and 2p orbitals less facilitate back bonding in BCl3!
Progressively BI3 must be still more acidic ,can you see similar logic!?
2026-08-04
Whichever substrate has more electron deficiency at B must be stronger Lewis acid.
Since both boron and fluorine are in second period of periodic table that's why they have p orbitals of the same sizes .
Thus 2p orbitals of fluorine overlap with the empty orbitals of boron by donating it's electron pair. This is called back bonding.
Back bonding in BCl3 is not likely as in case of BF3 because of the difference in size of p orbitals of Boron and Chlorine.
Due to back bonding the boron of BF3 becomes less electron demanding and thus BCl3 is the better Lewis acid here.
:)
Whichever substrate has more electron deficiency at B must be stronger Lewis acid.
Since both boron and fluorine are in second period of periodic table that's why they have p orbitals of the same sizes .
Thus 2p orbitals of fluorine overlap with the empty orbitals of boron by donating it's electron pair. This is called back bonding.
Back bonding in BCl3 is not likely as in case of BF3 because of the difference in size of p orbitals of Boron and Chlorine.
Due to back bonding the boron of BF3 becomes less electron demanding and thus BCl3 is the better Lewis acid here.
:)
More
VOTE
What ever has more electron deficiency at Boran center must be better electron acceptor,hence better Lewis acid,isn’t it?
Now both B and F are in second period of periodic table,so have comparable sizes ,so also p orbitals of similar dimensions
so the filled 2p orbitals of F overlap with those of empty orbitals of B in what is called as back bonding
Since back bonding makes B of BF3 less electron demanding than that of BCl3
Obviously BCl3 is better Lewis acid than BF3
Have recognised that difference in sizes of 3p and 2p orbitals less facilitate back bonding in BCl3!
Progressively BI3 must be still more acidic ,can you see similar logic!?
What ever has more electron deficiency at Boran center must be better electron acceptor,hence better Lewis acid,isn’t it?
Now both B and F are in second period of periodic table,so have comparable sizes ,so also p orbitals of similar dimensions
so the filled 2p orbitals of F overlap with those of empty orbitals of B in what is called as back bonding
Since back bonding makes B of BF3 less electron demanding than that of BCl3
Obviously BCl3 is better Lewis acid than BF3
Have recognised that difference in sizes of 3p and 2p orbitals less facilitate back bonding in BCl3!
Progressively BI3 must be still more acidic ,can you see similar logic!?
More
VOTE