[H_3–<i>n</i>Fe₄(CO)₁₂(IrCOD)]^<i>n</i>− (<i>n</i> = 1, 2) and [H₂Fe₃(CO)₁₀(IrCOD)]⁻ Bimetallic Fe–Ir Hydride Carbonyl\nClusters

Abstract

The\nreaction of [HFe₄(CO)₁₂]^3– (<b>1</b>) with [Ir­(COD)­Cl]₂ results in the formation\nof the bimetallic Fe–Ir monohydride carbonyl cluster [HFe₄(CO)₁₂(IrCOD)]^2– (<b>2</b>). This is quantitatively protonated by strong acids to the dihydride\n[H₂Fe₄(CO)₁₂(IrCOD)]⁻ (<b>3</b>). Further addition of acids to <b>3</b> results\nin the tetranuclear dihydride [H₂Fe₃(CO)₁₀(IrCOD)]⁻ (<b>4</b>) via formal oxidative\nelimination of a Fe­(CO)₂ fragment. Compounds <b>2</b>–<b>4</b> have been fully characterized by means of ¹H VT NMR spectroscopy, X-ray crystallography, and DFT calculations.\nIn <b>2</b> and <b>3</b> the Fe₄Ir cluster\ncore adopts a trigonal bipyramidal geometry, while the Fe₃Ir core in <b>4</b> is tetrahedral. In addition, ¹H VT NMR studies indicate that <b>2</b> and <b>3</b> are\nfluxional in solution, whereas <b>4</b> is not.