In this article: http://jredman.kombyonyx.com/thesis/Ch16.htm they mention "axial ligands" and "peripheral ligands". What exactly does that mean? Heres the molecule they use as an example: I can see that the porphyrin rings both have a metal ligand M binded to them. That oxygen atom which bridges the two M ligands, is that an "axial ligand"? Is it even a ligand at all, I thought a ligand meant an electrophilic species which accepts electrons from an electron doner and forms a dative bond. I'm used to oxygen atoms being an electron doner.