Why does ferrocene have a higher melting point than acetylferrocene?

Ferrocene is symmetrical while acetyl ferrocene is not symmetrical.

Explanation:

Acetyl ferrocene is attached to an acetyl group, the upper part of the ring is asymmetrical. On the other hand, ferrocene, whose rings are symmetrical (no groups attached to any of the rings) has a higher melting point due to symmetry.

This means that symmetry in a molecule implies a higher higher melting point.

As a general rule, symmetrical molecules in crystalline form usually have higher melting temperatures and exhibit lower solubilities when they are compared with molecules of similar structure but with lower symmetry.

Hydrogen and oxygen are being formed.