This chapter covers the literature related to the development of tervalent phosphorus acid derivatives, published during 2020. A critical selection of bibliographic material was reviewed, essentially focused on the synthetic strategies of new phosphorus(iii) ligands, metal complexes and some of their most relevant applications in catalysis. Several review articles have been published in the field, with particular emphasis on their catalytic applications.^1–16 

Several examples regarding the preparation of aminophosphine and their metal complexes were reported during the year 2020, including structural studies,^17–21  and catalytic applications, namely in hydroboration,^22,23  polymerisation,^24,25  and asymmetric hydrogenation.²⁶ 

Al-Masri²⁷  reported the synthesis of palladium and platinum complexes 3a and 3b, from ligand 2, which was prepared through reaction of p-aminoacetophenone 1 with two equivalents of chlorodiphenylphosphine (Scheme 1a). The complexes were fully characterised by standard spectroscopic and analytical methods, including crystallography, and were further evaluated as catalysts in Suzuki coupling reactions of arylbromides with phenylboronic acid. Only the palladium complex 3a was found to be catalytically active, particularly when electron-withdrawing groups were present at the arylbromide.