in ko2 o2 is in -1 state.now in case of complex we have to find in which state 02 is.
there is only one possibility +1because 02 can show 0,-1,-2 and +1.now first three are not possible because in complex
outside atom must have positive charge and charge cannot be 0,i.e. it cannot be neutral.
now o2(+) bond order=2.5 (calculated by molecular orbital theory)
02(-) bond order=1.5
hence bond length is 02(-) is larger than 02(+)
ko2>o2[asf4] .....(bond length )