Catalytic applications of small bite-angle diphosphorus ligands with single-atom linkers

Diphosphorus ligands connected by a single atom (R2PEPR2; E = CR2, C[double bond, length as m-dash]CR2 and NR) give chelating ligands with very small bite-angles (natural bite-angle of 72° for dppm) as well as enable access to other properties such as bridging modes and hemilability. Their use in catalysis has been growing over the last two decades as researchers have sought to apply the properties of small bite-angle ligands to a wide number of catalytic reactions, often complementing the well-established applications of wide bite-angle ligands in catalysis. This Perspective reviews the properties of diphosphorus ligands featuring a single-atom linker and their use in several catalytic transformations of alkenes, including selective ethene oligomerisation, ethene polymerisation and co-polymerisation with CO, hydroacylation and hydrogenation, as well as their use in transfer hydrogenation and hydrogen-borrowing reactions.