Preparation, Ligand Substitution, and Structural Stability of (η3-Allyl)dicarbonylnitrosyliron Complexes

Abstract [Fe(η3-allyl)(CO)2(NO)] complexes were prepared by the reaction of tetrabutylammonium tricarbonylnitrosylferrate with tosylates, trifluoroacetates and phosphonates of allylic alcohols and with allylic halides. However, acetates and carbonates of the allylic alcohols are ineffective for the preparation of the complexes. The reaction of [Fe{η3-(1-substituted allyl)}(CO)2(NO)] with phosphorus ligands (L) gave a mixture of diastereomeric [Fe{η3-(1-substituted allyl)}(CO)(NO)(L)] complexes, which have planar chirality and central chirality of the iron atom. Variable-temperature 1H NMR spectroscopy revealed that no isomerization between these diastereomers occurred upon heating up to 80 °C. Also, neither syn–anti isomerization of the allylic ligand nor isomerization of planar chirality of the complexes took place. The unsubstituted allylic ligand rotates about the iron-allyl ligand axis at room temperature, while η3-(1-substituted allylic) ligands do not.