Heterobimetallic-Mediated Dinitrogen Functionalization: N-C Bond Formation at Rhenium-Group 9 Diazenido Complexes.

We report the synthesis and characterization of rhenium-group 9 heterobimetallic diazenido species (η 5 -Cp)Re(μ-BDI)(μ-N 2 )M(η 4 -COD) ( 1-M , M = Ir or Rh, Cp = cyclopentadienide, BDI = N , N '-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate, COD = 1,5-cyclooctadiene), formed from salt elimination reactions between Na[(η 5 -Cp)Re(BDI)] and [MCl(η 4 -COD)] 2 . Additionally, we find that these same reagents react under an argon atmosphere to instead produce bridging hydride complexes (BDI)Re(μ-η 5 :η 1 -C 5 H 4 )(μ-H)M(η 4 -COD) ( 2 - M ), which undergo rearrangements upon protonation to form the alternative bridging hydrides [(η 5 -Cp)Re(μ-BDI)(μ-H)M(η 4 -COD)][(B( m -C 6 H 3 (CF 3 ) 2 ) 4 )] ( 3-M ). Further, we demonstrate the first example of N-C bond formation at a heterobimetallic dinitrogen complex through reactions of 1-M and methyl triflate, which produces the alkylated species [(η 5 -Cp)Re(μ-N(Me)N)(μ-BDI)M(η 4 -COD)][OTf] ( 4-M , OTf = trifluoromethanesulfonate). A combination of spectroscopic studies, X-ray structural analysis, and computational investigations is discussed as an aid to understanding the modes of dinitrogen activation within these unique heterobimetallic complexes.