Sterically Encumbering Ligands for the Synthesis and Stabilization of Iron Nitride and Iron Oxo Compounds

Asiel Mena, University of Texas at El Paso


The study of iron-nitrides has been found to be very attractive due to their potential role in processes like Haber-Bosch and nitrogen fixation by nitrogenase. The role of iron-nitrides in these processes is yet not well understood, and the fact that only handful of terminal iron-nitrides have been isolated or spectroscopically detected motivates us to study this type of systems, since much remains to be learned about the electronic and structural factors that affect the chemistry of the Fe≡N bond. Recently in our group, by using a super-bulky guanidinate ligand (LAr*), the obtention of an iron-nitride ([LAr*]FeN(py) (LAr* = (Ar*N)2C(NCtBu2), Ar* = 2,6-bis(diphenylmethyl)-4-tert-butylphenyl) was reported. Despite all efforts, the isolation of this molecule was not possible, being only stable at low temperatures in pyridine solutions. We postulate that by changing the backbone substituent the electronic properties of the ligand can be tuned, leading to stabilization of the iron-nitride bond. Five new super-bulky ligands were obtained and characterized. By reacting the protonated version of the super-bulky ligands with tetramesityl diiron (Fe2Mes4) three 3-coordinate iron mesityl complexes [LAr*-R]Fe(Mes) (R = piperidine, methyl and phenyl) were isolated and characterized. These iron mesityl complexes were reacted with 2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta-2,5-diene (Hdbabh) to produce two dbabh molecules [LAr*-Pip]Fe(dbabh) and [LAr*-Me]Fe(dbabh)(Hdbabh). Photolysis of these molecules produced activation of the dbabh fragments and led to unexpected isomerization processes.

Subject Area

Inorganic chemistry|Molecular chemistry|Organic chemistry

Recommended Citation

Mena, Asiel, "Sterically Encumbering Ligands for the Synthesis and Stabilization of Iron Nitride and Iron Oxo Compounds" (2023). ETD Collection for University of Texas, El Paso. AAI30818480.