Evidence for a π-donor effect in transition metal-carbon bonds from H—D coupling constants

Abstract

The coupling constants JH–D of the CH2D group in the deuteriomethyl derivatives, π-C5H5Fe(CO)2CH2D, π-C5H5(Mo or W)(CO)3CH2D, Mn(CO)5CH2D, π-C5H5Ni(Ph3P)R (where R = CH2D, m- or p-C6H4CH2D), and XPt(Et3P)2CH2D (where X = Br, NO3, or SCN), have been determined. The sign of JH–D in the iron compound has been shown to be negative. The magnitudes of JH–H are discussed in terms of a π-donor effect from the metal to the neighbouring carbon.