Activation of Dinitrogen Promoted by Adsorption of C₆H₆ on Fe₂VC^- Cluster Anions

The introduction of organic ligands is one of the effectivestrategiesto improve the stability and reactivity of metal clusters. Herein,the enhanced reactivity of benzene-ligated cluster anions Fe2VC(C6H6)(-) with respect to naked Fe2VC- is identified. Structuralcharacterization suggests that C6H6 is molecularlybound to the dual metal site in Fe2VC(C6H6)(-). Mechanistic details reveal that thecleavage of N VN is feasible in Fe2VC(C6H6)(-)/N-2 but hindered by anoverall positive barrier in the Fe2VC-/N-2 system. Further analysis discloses that the ligatedC(6)H(6) regulates the compositions and energy levelsof the active orbitals of the metal clusters. More importantly, C6H6 serves as an electron reservoir for the reductionof N-2 to lower the crucial energy barrier of N VNsplitting. This work demonstrates that the flexibility of C6H6 in terms of withdrawing and donating electrons is crucialto regulating the electronic structures of the metal cluster and enhancingthe reactivity.