Question

In both water and dimethyl ether \[\ce{(CH3 - \overset{\bullet\bullet}{\underset{\bullet\bullet}{O}} - CH3)}\], oxygen atom is central atom, and has the same hybridisation, yet they have different bond angles. Which one has greater bond angle? Give reason.

Answer 1

Dimethyl ether has larger bond angle than water. This is because there is more repulsion between bond pairs of \[\ce{CH3}\] groups attached in ether than between bond pairs of hydrogen atoms attached to oxygen in water. The carbon of \[\ce{CH3}\] group in ether is attached to three hydrogen atoms through c bonds and electron pairs of these bonds add to the electron charge density on carbon atom. Hence, repulsion between two \[\ce{^-CH3}\] groups will be more than that between two H atoms.