The formal oxidation state of a metal in a cmplx is the charge left on the metal after the ligands are removed in their closed-shell configuration: Cl as Cl^-, CN as CN^-, NO2 as NO2^-, and PPh3 as neutral PPh3
hence [Pt] -1(Cl) -1(CN) - 1 (NO2) – 0(PPh3) =+1 This is a Pt(IV) a common oxidation state of Pt.