Alkenyl (or aryl) iodide (or bromide) is readily reduced with CrCl2 is N,N-dimethylformamide at 25°C to gice the corresponding organochromium species which adds selectively to an aldehyde moiety without affecting the coexisting ketone or cyano group of the substrate.
inclination of other 17-electron metal carbonyl complexes to undergo associative ligand displacement reactions, it seems ironic that the incorporation of a pentadienyl ligand, which would be expected to promote associative attack via $ 73 coordination changes, should lead instead to a series of compounds for which much lower rates of substitution are observed and for which the substitutions also take place