Email Post: Bis(μ-4-bromo­benzoato)-κ(3) O,O′:O′;O:O,O′-bis­[μ-1,3-bis­(pyridin-4-yl)propane-κ(2) N:N′]bis­[(4-bromo­benzoato-κ(2) O,O′)cadmium]