In the 1 H NMR spectrum of 3c recorded at -35 °C two broad apparent triplets at δH = -14.92 and -15.93 ppm can be found for the bridging Fe-(μ-H)2-Al hydrides as well as another three broad signals at δH = 2.74, 1.03 and 0.64 ppm for the ArCH=CH2 protons of the coordinated alkene group. In the 31 P{ 1 H} NMR spectrum, the three PMe3 ligands of 3c appear as a well resolved ABX spin system; the AB part centred at δP = 36.5 ppm (JAB = 41.5 Hz) and the X part at 22.2 ppm. Alkene binding, while reversible, only leads to kinetic products in these reactions, over longer time periods activation of the vinylic C-H bonds was observed.