Fluorine Preparation:How can this be explained on basis of Lewis Acid-Base Reaction?
$\ce{2 K2MnF6 + 4 SbF5 → 4 KSbF6 + 2 MnF3 + F2↑}$

Occurs in two stages. First there is a (Lewis) acid-base reaction

$\ce{2 K2MnF6 + 4 SbF5 → 4 KSbF6 + 2 MnF4}$

where the Lewis acid $\ce{SbF5}$ accepts a lone pair from a fluorine in the manganese complex, and the adduct then falls apart to leave $\ce{MnF4}$. This is thermally unstable at ambient temperatures (Housecroft and Sharpe) and falls apart in the redox reaction

$\ce{2 MnF4 → 2MnF3 +F2}$