Isocyanide-functionalised phosphines: an uncharted field

While numerous functional phosphines have been reported, investigated, and applied to date, phosphines equipped with an additional isocyanide moiety have received only limited attention. This frontier article provides an overview of the chemistry of these compounds, which has not yet been comprehensively reviewed. In particular, different types of phosphinoisocyanides (viz., isocyanide-tethered phosphines as well as compounds featuring the direct P-NC bond) and routes towards them, in addition to the reactivity, coordination behaviour, and transformations of these molecules in both their native and coordinated forms, are discussed. In particular, this overview focuses on the synthesis, reactivity, and coordination properties of phosphines bearing the isocyanide moiety at the organic (aliphatic or aromatic) or organometallic (ferrocene) scaffold. Also discussed is the chemistry of isocyanophosphines of the R₂PNC type that arise, in metal-coordinated form (as C-donors), via reactions between cyano complexes and chlorophosphines. All these compounds have remarkable synthetic potential that mainly stems from the specific reactivity of isocyanides, which readily undergo diverse addition and insertion reactions, thereby providing access to, e.g., complexes with monodentate and P,C-chelate or bridged phosphinoisocyanide ligands and structurally unique carbene complexes.