Iron diazoalkane chemistry: N-N bond hydrogenation and intramolecular C-H activation

Treatment of the intermediate spin ferrous bis(dinitrogen) complex, ((PDI)-P-iPr)Fe(N-2)(2) ((PDI)-P-iPr = 2,6-(2,6-Pr-i(2)-C6H3NCMe2)(2)C6H3N), with 1 equiv of N2CHSiMe3 afforded the corresponding iron diazoalkane compound, ((PDI)-P-iPr)Fe(N2CHSiMe3). Spectroscopic studies in conjunction with the metrical parameters from the solid-state structure support an intermediate spin ferrous complex with a doubly reduced chelate and a neutral diazoalkane ligand. In solution at 23 degrees C, ((PDI)-P-iPr)Fe(N2CHSiMe3) promotes the intramolecular C-H activation of an isopropyl aryl substituent with loss of SiMe4. Exposure of ((PDI)-P-iPr)Fe(N2CHSiMe3) to 1 atm of H-2 resulted in hydrogenative cleavage of the N-N and N-C bonds to yield ((PDI)-P-iPr)Fe(NH3) and SiMe4. Similar N-N bond cleavage chemistry was observed upon addition of hydrazine to ((PDI)-P-iPr)Fe(N-2)(2).