I read that all ligands are Lewis bases but I then read that the number of anionic ligands attached to a metal will determine its oxidation state. Which is it? Lets use chlorine as an example. Before this ligand binds to the metal is it a Cl- ion or a neutral Cl atom? If its the former I can see how its a Lewis base because it provides both electrons for the bond. Conversely I don't see how it could "raise" the oxidation state of the metal if its actually bonded as a Lewis base. If its the latter (if its a neutral Cl atom) then I can see how it raises the oxidation state of the metal by 1 but I don't see how its a Lewis base. So to summarise the question, what are anionic ligands? Are they anions from the start or do they become anions by taking an electron from the metal?