Bimetallic Fe–Au Carbonyl Clusters Derived from Collman’s Reagent: Synthesis, Structure and DFT Analysis of Fe(CO)4(AuNHC)2 and [Au3Fe2(CO)8(NHC)2]−

The reaction of the Collman’s reagent Na2Fe(CO)4 with two equivalents of Au(NHC)Cl (NHC = IMes, IPr, IBu) in thf results in the bimetallic Fe(CO)4(AuNHC)2 (NHC = IMes, 2; IPr, 3; IBu, 4; IMes = C3N2H2(C6H2Me3)2; IPr = C3N2H2(C6H3iPr2)2; IBu = C3N2H2(CMe3)2) clusters in good yields. Heating 2 in dmf at 100 °C results in the higher nuclearity cluster [Au3Fe2(CO)8(IMes)2]− (5). 2–5 have been fully characterized via IR, 1H and 13C NMR spectroscopies and their structures determined by means of single crystal X-ray crystallography. Gas-phase DFT calculations were carried out on 2–5 and the model compound cis-Fe(CO)4(AuIDM)2 (6) (IDM = C3N2H2Me2), in order to better understand the metal–metal and metal–ligand interactions in these compounds without the influence of packing forces.