Rhenium(V) oxo complexes with bidentate schiff bases: Structures and catalytic applications

Reaction of [NBu₄] [ReOCl₄] (1) with bidentate salicylidene amine ligands (salen = HL) (2a-c) leads to the formation of monomeric octahedral rhenium(V) compounds of formula [ReOCl(L)₂] (3a-c). Spectroscopic data indicate asymmetric arrangement of the ligands in the complexes. This is confirmed by the X-ray crystal structures of 3b and 3c. Complexes 3a, b have been tested as catalysts for the epoxidation of cyclooctene. No evidence for decomposition of the catalysts is observed during the reaction (as in the case for tri- and tetradentate salen complexes). No undesired byproducts are formed in the catalytic reactions.