[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.