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(C6H (3) (i) Pr-2)(2); IBu = C3N2H2(CMe3)(2)) clusters in good yields. Heating 2 in dmf at 100 A degrees C results in the higher nuclearity cluster [Au3Fe2(CO)(8)(IMes)(2)](-) (5). 2-5 have been fully characterized via IR, H-1 and C-13 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.