Synthesis and Characterisation of N-Heterocyclic Carbene Adducts of PI Cations

The Macdonald research group has long been interested in the synthesis of compounds containing low-valent main group elements. Recently, more work was put forth in the synthesis and study of molecules containing phosphorous in its +1 oxidation state (PI ). One way of stabilizing the PI center is by using Nheterocyclic carbenes (NHCs). Our group previously reported several approaches to salts containing [(R NHC R\u27 ) 2 PI ]+ cations, most notably through ligand replacement reactions from precursors such as [(dppe)P I ]+ that we had developed previously. Various derivatives of cyclic [(RBis) PI ] and acyclic [(R NHCR\u27 )2 PI ]+ compounds have been synthesized. Experimental and computational investigation of the structural features, physical properties and reactivity patterns of such species are discussed. Evidence of π-delocalization from the electron rich phosphorus into the π-system is detailed with the cyclic system giving better delocalization due to the more planar arrangement forced by the bridging methylene. Oxidation and metal coordination reactions are performed on such compounds