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

Abstract

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.