${\mathrm{SiF}}_6^{-2}$ is known while ${\mathrm{SiCl}}_6^{-2}$ is not explain ?

i) Six large chloride ions cannot be accommidated around Si⁺⁴ due to limitation of its size.
ii) Interaction between lone pair of chloride ion and Si⁺⁴ is not very strong.