Question

Using the elemental, inductive, resonance and hybridizations effects, explain a scenario that would make for a strong Lewis base? i.e. in order to have a strong Lewis base, what kind of structural elements does it need to observe?  

Answer 1

If a species (i.e atoms, molecules or ions) is a strong Lewis Base, then it will have a LOCALIZED HOMO or in simple words, it will definitely have LONE PAIR OF ELECTRONS.

For example - , ,

Generally, Lewis bases are also the -systems of high electron density which have a great potential to donate electron pair. This is why some fantastic Lewis bases are the Pyridine and some of its derivatives.

Let us discuss why the molecules are strong Lewis bases-

• All the lewis bases must contain NEGATIVE CHARGE or ELECTRON PAIR in HIgh Electronegative Atoms like O, N, S, F, etc.
• Due to the high electronegativity of the atoms which donates the Lone pair, it applies high Inductive effect through bonds and creates high electron density around itself.
• Typical Lewis Bases have their charge localized in the electronegative donor atom because delocalization of negative charge(or Lone pair) would make the species stable and reluctant towards the donation of negative charge or lone pair.
• There are no criteria for any hybridization for lewis bases.

Some of the typical lewis bases can be shown as follows-