Effect of pressure on the electronic structure of ferric hydroxamates and ferrichrome A.

The effect of pressure up to 175 kilobars on the electronic structure of three ferric hydroxamates and on ferrichrome A has been studied by optical absorption and Mössbauer resonance. The ferric ion was reduced to ferrous ion with pressure, as has been previously observed for various compounds. For the hydroxamates, the amount of reduction correlated very well with the location and shift of the metal-to-ligand charge transfer peak. This is entirely consistent with a previously presented theory. The results for ferrichrome A did not fit quantitatively into the series. Since the shape of the potential well is almost certainly different for this compound, this result is not surprising.