Bent Phosphaallenes With "Hidden" Lone Pairs as Ligands.

Phosphaheteroallenes R−P=C=L, with L = N‐heterocyclic carbenes (NHCs), can be viewed to a certain extent as phosphaisonitriles stabilized with NHCs, R−P=C:←L. The suitability of these molecules as ligands for coinage‐metal ions was investigated and coordination through the central carbon center was observed in most cases. A combination of experiments, spectroscopic methods, and DFT calculations indicates the presence of a hidden electron pair at the carbon center of R−P=C:←L. Remarkably, this lone pair also inserts intramolecularly in C−H bonds showing the carbene‐type reactivity which is expected for phosphaisonitriles. [ABSTRACT FROM AUTHOR]