Additionally, there has been some controversy regarding the fate of N2 once bound to FeMoco: some researchers have conjectured that its reduction to ammonia occurs while it remains bound to a single Fe atom, whereas others have suggested that an intermediate step in which the molecule associates to both Fe2 and Fe6 may be necessary to achieve the required extent of activation to induce reduction (Figure ). Note that the discrepancies described above relate to only a single example of a (FeMoco) nitrogenase. Given how brittle the fine-grained details of the characterized mechanisms appear to be, it is not unlikely that chemical changes associated with different nitrogenases will cause additional variations in the sequence of reaction steps.