C Cl_(4) does not act as Lewis acid while SiCl_(4) and SnCl_(4) act as Lewis acids. Why?

C Cl_(4) does not act as Lewis acid while SiCl_(4) and SnCl_(4) act as

1.	C Cl_(4) does not act as Lewis acid while SiCl_(4) and SnCl_(4) act as Lewis acids. Why?
Answer» SOLUTION :`SiCl_(4) and SnCl_(4)` act as Lewis acids. This is because they can EXTEND their coordination NUMBER beyond FOUR due to the presence of vacant d-orbitals in the valance shell