Three novel iron dinitrogen hydrides, [FeH(iPr-PSiMeP)(N2)(PMe3)] (1), [FeH(iPr-PSiPhP)(N2)(PMe3)] (2), and [FeH(iPr-PSiPh)(N2)(PMe3)] (3), supported by a silyl ligand are synthesized for the first time by changing the electronic effect and steric hindrance of the ligands through the reaction of ligands L1–L3 with Fe(PMe3)4 in a nitrogen atmosphere. The ligands containing an electron-donating group with large steric hindrance on the phosphorus atom are beneficial for the formation of dinitrogen complexes. A penta-coordinate iron hydride [FeH(iPr-PSiPh)(PMe3)2] (4) was formed through the reaction of ligand L3 with Fe(PMe3)4 in an argon atmosphere under the same conditions. The reactions between complexes 1–3 with an atmospheric pressure of dihydrogen gas resulted in Fe(II) dihydrides, [(iPr-PSiMe(μ-H)P)Fe(H)2(PMe3)] (5), [(iPr-PSiPh(μ-H)P)Fe(H)2(PMe3)] (6) and [(iPr-PSiPh(μ-H))Fe(H)2(PMe3)2] (7), with an η2-(Si–H) coordination. The isolation of dihydrides 5–7 demonstrates the ability of the dinitrogen complexes 1–3 to realize the activation of dihydrogen under ambient temperature and pressure. The molecular structures of complexes 1–7 were elucidated by single crystal X-ray diffraction analysis. The iron dinitrogen hydrides 1–3 are effective catalysts for the silylation of dinitrogen under ambient conditions and among them 3 is the best catalyst.
