Question

sncl2 act both Lewis acid and Lewis base WHY

Answer 1

yes. it act both lewis acid and Lewis base.
It is act as both but it is based on the situation of the reaction field.

if electron need , Sn use their vacant d orbital to bond formation.
otherwise, chlorine donate their lone pair in some cases.
mostly it is Lewis acid.

Answer 2

$SnCl_2$ can act as both Lewis acid and Lewis base.

• The species which can donate its lone pair of an electron can act as a lewis base. In the case of $SnCl_2$, the lone pair of the Cl atoms can donate an electron and act as a Lewis base.
• The species which can accept lone pair of an electron can act as a lewis acid. In the case of $SnCl_2$, the vacant d orbital of Sn can accept electrons act as a Lewis acid.