Why aluminum trifluoride has high boiling point then silicon tetrafluoride which is a gas?

Answer 1

AlF3 exist as a dimer in the form Al2F6 as there are attraction between two dimers they are difficult to seperate therefore it has high melting point. In case of SiF4 no dimer is formed

Answer 2

The higher boiling point of aluminum trifluoride compared to silicon tetrafluoride is due to the stronger intermolecular forces present in aluminum trifluoride. The aluminum atom can form stronger dipole-dipole interactions and van der Waals forces with neighboring molecules, leading to a higher boiling point. In contrast, silicon tetrafluoride exists as a gas due to its weaker intermolecular forces of attraction, resulting in a lower boiling point.