Poly-Phosphindenes

The humble phosphorous atom has played a pivotal role in chemistry since its early discovery by Hennig Brandt in 1669. This key element now forms the basis of the broader family of phosphine ligands, without which the catalysis community would be at a serious loss! Still, moving to lower valent P-chemistry still holds many surprises…

Our phosphorous research focuses on transformations of carbene-stabilised aryl phosphinidenes (also described as inversely polarised phosphalkenes). More specifically, we develop diverse bis-phosphinidene scaffolds, which are a new class of phosphorous compound, in order to explore their utility in a few ways:

(i) A phosphinidene centre has two lone pairs of electrons. That’s twice the amount of a classical phosphine! We explore the effect this can have when bis-phosphinidenes are used as ligands in catalysis

(ii) Carbene-stabilised arylphosphinidenes are typically intensely orange in colour, owing to charge-transfer into the compound’s pi-system. What about bis-phosphinidenes, and extended pi-systems? We’re starting to find that we can tune these absorptions, towards strongly red-absorbing compounds, based solely on aromatic substitution patterns.

(iii) Our main focus with our bis- and poly-phosphinidenes is the phosphinidene transfer reaction. We have shown that we can couple two bis-phosphinidene units together in a controlled, templated manner, forming unprecedented macrocycles. We’re now looking to make bigger ring systems, and ultimately metal-decorated Inorganic Covalent Networks (ICNs), for application in heterogeneous catalysis and photosensitisation applications.