Molecule matters- High oxdiation state: Fe^VI in an octahedral coordination complex

Abstract

The synthesis of a Fe^VI complex in an octahedral coordination geometry has been achieved recently by Wieghardt and coworkers. This is only the second hexavalent iron complex known after the tetrahedral ferrate ion, [FeO₄]^2-. The synthesis of the new Fe^VI complex involves a low temperature photolysis of an Fe^IV(N₃) precursor which leads to the formation of the Fe^VI complex containing a Fe≡ N triple bond. The structural characterization of the Fe^VI complex has been achieved by a variety of spectroscopic techniques including Mossbauer spectroscopy and X-ray absorption spectroscopy. Experimentally it is found that the Fe^VI complex is diamagnetic. Theoretical calculations reveal that the Fe^VI complex has an electronic configuration 3d² (S = 0); the d electrons are paired in a d_xy orbital.