PH3 as a Phosphorus Source for Phosphinidene-Carbene Adducts and Phosphinidene-Transition Metal Complexes

The parent phosphinidene-carbene adduct NHC=PH is a versatile synthon in main group chemistry and can act as an electronically flexible ligand for transition metals. Previously, it could only be synthesized with sterically demanding N-aryl substituents. This paper describes simple methods for the synthesis of NHC=PH adducts with varying steric demand from elemental phosphorus or easily accessible phosphorus sources. Furthermore, the reactivity of NHCs towards PH3 was investigated. It was shown how a NHC inserts into the P-H bond of PH3, which opens up a route to NHC=PH adducts from an imidazolium salt and PH3. The adducts were used in the simple syntheses of bis(phosphinidene) mercury(II) and group 6 pentacarbonyl parent phosphinidene complexes. Their electronic and structural properties were investigated to elucidate the influence of the NHC on the phosphinidene and identify possible applications.