Preparation of methyl and acetyl complexes of iron(II)

Abstract

The complexes [Fe(CO)₂(PMe₃)₂(Me)X], where X = Br, Cl, CN, NCS, CNO, OMe, or Me, have been synthesized and the structure assigned on the basis of i.r. and n.m.r. evidence. The complexes react readily and reversibly with CO to give the acetyl derivatives with the acetyl group in the cis position relative to X. When X = I, Br, or Cl the cis isomer rearranges slowly to the trans isomer until an equilibrium is obtained. The results are interpreted in terms of the σ- and π-accepting capabilities of the ligands.