Bimetallic Fe–Ir and Trimetallic Fe–Ir–Au Carbonyl Clusters Containing Hydride and/or Phosphine Ligands: Syntheses, Structures and DFT Studies

The reaction of [HFe4(CO)12(IrCOD)]2− (1) with CO at ambient conditions afforded [HFe4Ir(CO)14]2− (2), that, in turn, reacted with HBF4·Et2O affording [Fe4Ir(CO)15]− (3). 1 reacted with a slight excess of PPh3 resulting in a mixture of [HFe2Ir2(CO)10(PPh3)2]− (ca. 37%) (5) and [H2Fe3Ir(CO)10(PPh3)2]− (ca. 63%) (6). 5 and 6 co-crystallized as their [NEt4][H1+xFe2+xIr2-x(CO)10(PPh3)2]·CH2Cl2 (x = 0.63) salt. The reaction of 1 with Au(PPh3)Cl afforded [Fe3Ir(CO)12(AuPPh3)]2− (7). The related hydride [HFe3Ir(CO)12]2− (9) was prepared from the reaction of [HFe4(CO)12]3− (8) with [Ir(COE)2Cl]2 (COE = cyclo-octene). For sake of comparison, [HFe3Co(CO)12]2− (10) was obtained from 8 and Co2(CO)8. All the new clusters have been fully characterized via IR, 1H,13C{1H} and 31P{1H} NMR spectroscopies and their structures determined by means of single crystal X-ray crystallography. Possible isomers have been investigated by DFT calculations.