Synthesis, X-ray Structure, and Reactivity of Phosphine-Substituted Iron Carbonyl Complexes Containing <i>σ</i>-Alkyl−<i>π</i>-Allyl Ligands

The synthesis, structure, and reaction chemistry of dicarbonyl phosphine and carbonyl diphosphine iron complexes with σ-alkyl−π-allyl ligands derived from ring-opened pinene systems are described. X-ray diffraction studies on three representative examples were performed and showed significant differences in the orientation of the phosphine ligands with respect to the σ-alkyl−π-allyl ligands. These differences are caused by steric interactions, as shown by the fluxional behavior of some of the complexes on the NMR time scale. The influence of the phosphine ligand is demonstrated by the reaction of these complexes with CO/AlCl3 and their photolysis products in acetic acid.