Synthesis, structure and reactions of a dinitrogen complex of iron(0), [Fe(N2)(depe)2] (depe = Et2PCH2CH2PEt2)

Abstract

Reduction of [FeCl₂(depe)₂] (depe = Et₂PCH₂CH₂PEt₂) by sodium–naphthalene under nitrogen gave a dinitrogen complex of iron(0), [Fe(N₂)(depe)₂] 1, in 72% yield. The crystal structure of 1 shows that the dinitrogen ligand bonds in an end-on fashion in a trigonal-bipyramidal geometry. Protonolysis of 1 by HCl gave trans-[FeH(Cl)(depe)₂] with quantitative evolution of molecular nitrogen and then [FeCl₂(depe)₂] with molecular hydrogen. The dinitrogen ligand in 1 can be replaced by small molecules such as CO, CS₂ or H₂ to give [Fe(CO)(depe)₂], [Fe(CS₂)(depe)₂] and cis-[FeH₂(depe)₂] respectively. The molecular structure of [Fe(CO)(depe)₂] has been established by X-ray analysis.