Q.
In BrF3 molecule, the lone pairs occupy equatorial positions to minimize
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Chemical Bonding and Molecular Structure
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Solution:
It is to minimize lone pair - bond pair repulsions only. The three possible structures of BrF3 molecule are:
I. One lp−lp repulsion at ∼120∘
Two lp−bp repulsions at ∼120∘
Four lp−bp repulsions at 90∘
Two bp−bp repulsions at 90∘ and
One bp−bp repulsion at 180∘
II. One lp−lp repulsion at 90∘
Three lp−bp repulsions at 90∘
Two lp−bp repulsions at ∼120∘
One lp−bp repulsions at 180∘
Two bp−bp repulsions at 90∘ and
One bp−bp repulsion at ∼120∘
III. One lp−lp repulsion at 180∘
Six lp−bp repulsions at 90∘ and
Three bp−bp repulsions at 120∘
Now, it is given that the Br3 molecule prefers structure(I). In this structure, (a) lp−lp repulsions are not minimum; it is minimum in structure (III). (b) lp−bp repulsions are less than structure (III). (c) bp−bp repulsions are more than structure (III).
