[8]Ferrocenophanes with two nitrogen atoms in bridging positions: Synthesis via olefin metathesis, structure and solution dynamics

The ruthenium-catalysed ring-closing metathesis of 1,1′-bis(aminomethyl)ferrocenes provided [8]ferrocenophanes with two nitrogen atoms in the bridge and the (E)–configuration of the newly formed carbon–carbon double bond. The X-ray single-crystal diffraction analyses revealed that the new compounds are axially chiral and have both N–substituents occupying the pseudoequatorial positions of the macrocycle. The distance between the two nitrogen atoms suggests their potential applications as bidentate ligands. Solution behaviour of the diaza[8]ferrocenophanes was investigated by means of variable temperature NMR spectroscopy. Theoretical studies confirmed that the rotational isomer found in the solid state is thermodynamically the most stable.