On the syntheses, NMR spectroscopic and structural characterisations of [CuL(C2H4)]·PF6 and [Cu2L2(μ-C4H6)]·2PF6: L = (±)-N,N′-bis(2,4,6-trimethylbenzylidene)-1,2-diaminocyclohexane

Copper(I) (±)-N,N′-bis(2,4,6-trimethylbenzylidene)-1,2-diaminocyclohexane reacts with either ethene or butadiene to give the corresponding alkene complexes. In each case crystallographic studies show that the alkene coordinates in an η2 fashion. In the butadiene complex a dimer is formed where the butadiene bridges two copper complexes. Variable temperature NMR spectroscopy of the ethene adduct demonstrates fluxional behaviour, which is attributed to the rotation of the coordinated ethene relative to the complex, ΔG‡255 = 50 ± 2 kJ mol−1.