posted by Bob .
what transition metal complex is responsible for transporting oxygen in our blood? Also, what is its structure?
The transition metal (there are several transition series---I assume you are referring to the 3d transition metals) is iron. As to its sturcure, the iron itself has no structure other than its electronic structure. It is the metal in hemoglobin.I will try to find the structure of the complex on the net and post it later.
Here is the structure of hemoglobin.