Iron Diazoalkane Chemistry: N−N Bond Hydrogenation and Intramolecular C−H Activation

Treatment of the intermediate spin ferrous bis(dinitrogen) complex, (iPrPDI)Fe(N2)2 (iPrPDI = 2,6-(2,6-iPr2−C6H3NCMe2)2C6H3N), with 1 equiv of N2CHSiMe3 afforded the corresponding iron diazoalkane compound, (iPrPDI)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 °C, (iPrPDI)Fe(N2CHSiMe3) promotes the intramolecular C−H activation of an isopropyl aryl substituent with loss of SiMe4. Exposure of (iPrPDI)Fe(N2CHSiMe3) to 1 atm of H2 resulted in hydrogenative cleavage of the N−N and N−C bonds to yield (iPrPDI)Fe(NH3) and SiMe4. Similar N−N bond cleavage chemistry was observed upon addition of hydrazine to (iPrPDI)Fe(N2)2.