Synthesis of Bis(silylene) Iron Chlorides and Their Catalytic Activity for Dinitrogen Silylation.

In this study, three tetracoordinated bis(silylene) iron(II) chlorides, namely, [SiCHRSi]FeCl 2 ( 1 ) (R = H), ( 2 ) (R = CH 3 ), and ( 3 ) (R = Ph), were synthesized through the reactions of the three different bis(silylene) ligands [LSiCHRSiL] (L = PhC(NtBu) 2 , L1 (R = H), L2 (R = CH 3 ), L3 (R = Ph)) with FeCl 2 ·(THF) 1.5 in THF. The bis(silylene) Fe complexes 1-3 could be used as effective catalysts for dinitrogen silylation, with complex 3 demonstrating the highest turnover number (TON) of 746 equiv among the three complexes. The catalytic mechanism was explored, revealing the involvement of the pentacoordinated bis(dinitrogen) iron(0) complexes [SiCHRSi]Fe(N 2 ) 2 (THF), ( 4 ) - ( 6 ), as the active catalysts in the dinitrogen silylation reaction. Additionally, the cyclic silylene compound 10 was obtained from the reaction of L1 with KC 8 . Single-crystal X-ray diffraction analyses confirmed the molecular structures of complexes 1-3 and 10 in the solid state.