Azophosphines: Synthesis, Structure and Coordination Chemistry

The conceptual replacement of nitrogen with phosphorus in common organic functional groups unlocks new properties and reactivity. The phosphorus-containing analogues of triazenes are underexplored but offer great potential as flexible and small bite-angle ligands. This manuscript explores the synthesis and characterisation of a family of air-stable azophosphine-borane complexes, and their subsequent deprotection to the free azophosphines. These compounds are structurally characterised, both experimentally and computationally, and highlight the availability of the phosphorus lone pair for coordination. This is confirmed by demonstrating that neutral azophosphines can act as ligands in Ru complexes, and can coordinate as monodentate or bidentate ligands in a controlled manner, in contrast to their nitrogen analogues.

Functional groups are fundamentally important for synthetic chemists and enable rational understanding of reactivity. Azophosphines are underexplored compounds that are heavier congeners of triazenes, and we have devised a general synthesis to this family of compounds. The availability of the phosphorus lone pair enabled them to be used as ligands that can bind in different coordination modes in a controlled manner. image