# Order of Lewis acid character among sulfur hexafluoride, sulfur tetrafluoride and tetrachloromethane

### Problem

Compare the order of Lewis acid character of $$\ce{SF6},$$ $$\ce{SF4}$$ and $$\ce{CCl4}.$$

### My attempt

Oxidation state of $$\ce{S}$$ in $$\ce{SF6}$$ is $$+6,$$ so it is very electrophilic. $$\ce{S}$$ has a lone pair on it in $$\ce{SF4},$$ but can expand its octet if attacked by a donor.

$$\ce{C}$$ cannot accept lone pair from donor.

So, the order should be $$\ce{SF6} > \ce{SF4} > \ce{CCl4},$$ but that is a wrong answer.

• S wrapped by 6 F has not much sterical chance to reach for some external e pair donor. It is almost inert. – Poutnik Nov 27 '20 at 9:10