Interpretation of tungsten-183–phosphorus-31 nuclear spin coupling constants

Abstract

Coupling constants are reported for tributylphosphine and triphenyl phosphite complexes [W(CO)₅P], cis- and trans-[W(CO)₄P₂], fac-[W(CO)₃P₃], and fac-[W(CO)₃(o-phen)P]. An earlier suggestion, based on results for [W(CO)₅P] and [W(CO)₄P₂], that the coupling constants are determined by the W–P π-bond strength, is shown to be inconsistent with the new results on the basis of a simple model for assessing trends in π-bond strengths. The variations in couplings with the nature of groups attached to phosphorus are also discussed.