The Detection of PHIP Effects Allows New Insights into the Mechanism of Olefin Isomerisation during Catalytic Hydrogenation

PHIP (parahydrogen-induced polarisation) effects in the H-1 NMR spectra of the products of Rh-complex-catalysed alkyne hydrogenation brings to light the fact that the cis-trans isomerisation of the formed olefin occurs through the formation of a sigma-bonded intermediate stabilised by the reversible addition of a hydrogen molecule at the metal centre. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)