The decreasing order of power of boron halides to act as Lewis acids is

Question

The decreasing order of power of boron halides to act as Lewis acids is (A) BF3 > BCl3> BBr3 (B)  BBr3 > BCl3>BF3  (C)  BCl3>BF3 >BBr3  (D)  BCl3 >BBr3 >BF3

Tardigrade Admin · Accepted Answer

It is due to pπ-pπ back bonding. All halides have lone pairs, they donate one lone pair to boron by overlapping with the p orbital of boron. An effective overlap between orbitals decreases due to the large size of p orbital of halides. Hence, electron deficiency of boron atom in its halides is - BBr3, > BCL 3 > BF 3 A species which is more electron deficient will accept electron easily and hence will be more acidic. <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/chemistry/7a42c53f67dafe60942ede5432fd515b-.png" />

Q. The decreasing order of power of boron halides to act as Lewis acids is

$B F_{3} > BC l_{3} > BB r_{3}$

$BB r_{3} > BC l_{3} > B F_{3}$

$BC l_{3} > B F_{3} > BB r_{3}$

$BC l_{3} > BB r_{3} > B F_{3}$

Q. The decreasing order of power of boron halides to act as Lewis acids is

BF3​>BCl3​>BBr3​

BBr3​>BCl3​>BF3​

BCl3​>BF3​>BBr3​

BCl3​>BBr3​>BF3​

$B F_{3} > BC l_{3} > BB r_{3}$

$BB r_{3} > BC l_{3} > B F_{3}$

$BC l_{3} > B F_{3} > BB r_{3}$

$BC l_{3} > BB r_{3} > B F_{3}$