${MCl}_{3} \cdot 2 {~L} \stackrel{{Ex} . {AgNO}_{3}}{\longrightarrow} 1 {~mole} \text { of } {AgCl}$
Its means that one ${Cl}^{-}$ion present in ionization sphere.
$\therefore \text { formula }=\left[{MCl}_{2} {~L}_{2}\right] {Cl}$
For octahedral complex coordination no. is $6$
$\therefore {L}$ act as bidentate ligand