Suppose that a BF3 molecule approaches the lone pair on the N atom of an :NH3 molecule,

Question:

Suppose that a BF3 molecule approaches the lone pair on the N atom of an :NH3 molecule, and that a bond forms between the B atom and the N atom. Consider the arrangement of electron pairs about the B atom at the moment of this bond formation, and describe the repulsions among the electron pairs and how they might be expected to change the geometry about the B atom.