Carbonyl ligand substitution of an aminerhenium benzyl complex. Interconversion of η1- and η3-benzyl complexes

Removal of a CO ligand from the η1-benzyl complex [Re(CO)2(η1-CH2Ph){NH(Me)CH2CH2(η5-C5H4)}]+Br– yielded an η3-benzyl complex. The η3 co-ordination mode was converted into η1 when the compound was dissolved in acetonitrile. Evaporation of acetonitrile removed the labile acetonitrile ligand and regenerated the η3-benzyl complex. The η3-benzyl complex [Re(CO)(η3-CH2Ph){NH(Me)CH2CH2(η5-C5H5)}]+BF4– is stable to air and moisture. The corresponding perrhenate salt has been characterized crystallographically. The tetrafluoroborate reacted with bromide, chloride and acetate anion to give the corresponding neutral η1-benzyl complexes in excellent yield. When treated with two-electron donor ligands, such as tert-butyl isocyanide and pyridine, it was converted into the corresponding (η1-benzyl)(isocyanide) and pyridine complexes.