Nitrogen-phosphorus heterocycles abound

Chemists over the years have explored countless ways to incorporate boron, nitrogen, oxygen, phosphorus, sulfur, and other elements into carbon ring systems. Creating these so-called heterocyclic compounds is like adding new flavors to a menu for chemists to try out, for example, when making optoelectronic materials, creating new catalysts, or developing new drugs. Continuing the trend, two research groups are reporting the addition of new types of nitrogen-phosphorus heterocycles. In one example, Hansjörg Grützmacher of ETH Zurich, Zoltán Benkő of Budapest University of Technology & Economics, and coworkers have prepared annulated 1-aza-3,4-diphospholides by adding sodium phosphaethynolate to 2-chloropyridines (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201705473). Cyano-substituted versions of the azaphospholides are deeply colored and have widely tunable optical properties, which could make them useful as ion sensors or as precursors for fabricating light-emitting diodes. In the other example, Ian Manners and coworkers of the University of Bristol have prepared 1-aza-2,3,4-triphospholenes by catalytically clicking together cyclophosphines and various nitriles (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201704991). The researchers found the chemistry can be used to functionalize cyano groups on polymers, and the electron-rich free heterocycles exhibit strong coordination properties, which could make them useful as ligands for heterobimetallic catalysts.