Beyond Triphos – New hinges for a classical chelating ligand

Branched triphosphine ligands have been less widely studied than mono- and bi-dentate analogues. The most studied ligand of this type is Triphos Ph (CH 3 C(CH 2 PPh 2 ) 3 ). Substitution of the apical C CH 3 moiety with boron, silicon, tin, nitrogen or phosphorus fragments has generated a new family of ligands, in some cases displaying varying coordination chemistry and reactivity to the parent carbon-based system. This review includes the synthetic strategies implemented to afford these ligands, as well as derivatives by way of varying the phosphine substituents. Although not exhaustive, relevant types of reported complexes featuring these ligands are discussed, as well as their reactivity and catalytic applications. Through critical analysis, common themes and chemical trends across this family of apical heteroatomic, branched triphosphines can be identified, leading to improvements in current chemical applications, as well as new areas that remain underdeveloped.