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

Abstract

The coupling constants J_H–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 J_H–D in the iron compound has been shown to be negative. The magnitudes of J_H–H are discussed in terms of a π-donor effect from the metal to the neighbouring carbon.