Oxygen and I

Oxygen is a remarkable element and without it in its triplet, more stable state, complex life on earth would not be possible. The singlet carbon-hydrogen bond does not react readily with oxygen because of the spin barrier. Nature has, however, solved this problem by using iron based enzymes either of the heme-type (porphyrin ligand) or of the non-heme type. The P-450 enzymes are illustrative of the first kind. Methane monooxygenase (MMO) is a good example of the second type. Recent work on the selective functionalization of saturated hydrocarbons has provided a system which, like MMO, has a mu-oxo-di-iron center with obligatory carboxylate complexation. In this system, two manifolds, Fe-II-Fe-IV and Fe-III-Fe-V provide two different processes for the selective conversion of saturated hydrocarbons into ketones.