[joyb]

"On binding of a molecule of oxygen by hemocyanin,the two copper ions become oxidised from Cu⁺ to Cu²⁺ and the oxygen molecule takes on a -2 charge. Suggest why 2Cu⁺ is used by the protein to bind O₂^- rather than 2Cu⁺ to a neutral O₂ molecule."

I'm not sure what to put here... I wrote a bit about the electrostatic attraction being greater, but oxygen needs to dissociate as much as it needs to associate. Please help?