Synthesis, reactivity, electrochemical behaviour, and molecular structure of crown ether cyrhetrene complexes

•Cyrhetrenyl crown ether complexes have been synthesized.•Imine species were isolated as a single isomers.•These complexes have the anti-(E) conformation in solid state.•The redox behaviour of starting material and imine complexes were studied.

Cyrhetrenyl crown ether complexes [(η5-C5H4CHN-M)Re(CO)3] (where M = 4-benzo-15-crown-5 (3a), 4-benzo-18-crown-6 (3b), 2-methyl-15-crown-5 (3c), or 2-methyl-18-crown-6 (3d)) were synthesised from cyrhetrenylcarboxaldehyde (1) and the corresponding crown ether amines 2a–d. All the complexes were characterised by IR spectroscopy, 1H and 13C NMR spectroscopies, and mass spectrometry. The stereochemistry for imine compounds 3a–d were determined using the 1H and 13C NMR spectroscopy data, which indicated that these complexes have the anti-(E) conformation. This was also confirmed by the X-ray crystal structures of 3b and 3c in the solid state. Additionally, the electrochemical behaviours of 1 and 3a–d were studied.

Graphical abstractCyrhetrenyl crown ether complexes were synthesised from cyrhetrenylcarboxaldehyde and the corresponding crown ether amines. These complexes have the anti-(E) conformation. Electrochemical behaviours of imine and precursor were studied.Figure optionsDownload full-size imageDownload as PowerPoint slide