[H3-nFe4 (CO) 12 (IrCOD)]n- (n = 1, 2) and [H2Fe3(CO)10(IrCOD)]- bimetallic Fe-Ir hydride carbonyl clusters

The reaction of [HFe4(CO)(12)](3) (1) with [Ir(COD)Cl](2) results in the formation of the bimetallic FeIr monohydride carbonyl cluster [HFe4(CO)(12)(IrCOD)](2) (2). This is quantitatively protonated by strong acids to the dihydride [H(2)Fe4(CO)(12)(IrCOD)]- (3). Further addition of acids to 3 results in the tetranuclear dihydride [H2Fe3(CO)(10)(IrCOD)]- (4) via formal oxidative elimination of a Fe(CO)(2) fragment. Compounds 24 have been fully characterized by means of H-1 VT NMR spectroscopy, X-ray crystallography, and DFT calculations. In 2 and 3 the Fe4Ir cluster core adopts a trigonal bipyramidal geometry, while the Fe3Ir core in 4 is tetrahedral. In addition, H-1 VT NMR studies indicate that 2 and 3 are fluxional in solution, whereas 4 is not.