Arrange the following compounds in the icreasing order of bond length of O-O bond `O _(2), O _(2) [AsF_(6)] ,KO _(2)` and peroxide ion. Explain on the basis of ground state electronic configuration of dioxygen in these molecules.

Explanation

`O_(2) [AsF_(6)]` has ` O_(2)^(-) ` ion while `KO_(2) ` has ` O_(2)^(-)` ion .
E.C. of ` O_(2) = KK sigma _(2s)^(2) sigma _(2s)^(**2) sigma _(2p_(z))^(2) pi_(2p_(x))^(2)pi_(2p_(y))^(2)pi_(2p_(x))^(**1)pi_(2p_(y))^(**1) " "` Bond order ` (1)/(2) (8-4) = 2 `
E.C. of ` O_(2)^(+) = KK sigma _(2s)^(2) sigma _(2s)^(**2) sigma _(2p_(z))^(2) pi_(2p_(x))^(2)pi_(2p_(y))^(2)pi_(2p_(x))^(**1)pi_(2p_(y))^(**0) " "` Bond order ` = (1)/(2) (8-3) = 2.5`
E.C. of ` O_(2)^(-) = KK sigma _(2s)^(2) sigma _(2s)^(**2) sigma _(2p_(z))^(2) pi_(2p_(x))^(2)pi_(2p_(y))^(2)pi_(2p_(x))^(**2)pi_(2p_(y))^(**1) " "` Bond order `= (1)/(2) (8-5) = 1.5 `
Higher the bond order , smaller is the bond length . Hence , order of O-O bond length is :
` O_(2) [AgF_(6)] lt O_(2) lt KO_(2)`.