How Nature Activates the C-H Bond in Methane: Lessons from a Combination of Spectroscopy and Quantum Chemistry

Transition metals are of vital importance in the active sites of metalloenzymes where they catalyze the most demanding reactions known in chemistry with remarkable efficiency and selectivity under the mildest chemical conditions. One of the dream reactions in organic chemistry is the selective oxidation of unactivated C-H bonds. In biochemistry, this task is accomplished by a number of iron and copper containing metalloenzymes. However, the activation of methane is not only the most challenging of these reactions, but also one of the biochemically most important. Major efforts have been invested in understanding from a mechanistic perspective how methane monooxygenases accomplish this difficult task. We have recently re-investigated this important problem through a combination of high-level spectroscopy and quantum chemistry. The results shed new light on the structure of the key intermediate known as „intermediate Q.