PNP Ligands in Cobalt-Mediated Activation and Functionalization of White Phosphorus

Transition-metal mediated white phosphorus activation is of high interest as an ecological alternative to P₄ chlorination pathway to the practically useful phosphorus products. Herein, we report a facile approach for P₄ activation, transformation and subsequent functionalization using cobalt complexes bearing PNP ligands. The use of N,N-bis(diphenylphosphino)amine as a ligand allows one to transform P₄ tetrahedron into a zig-zag chain with the formation of complex [Co(Ph₂ PNHP(Ph₂ )PPPPP(Ph₂ )NHPPh₂ )]BF₄ (4). The presence of organic substituent at nitrogen atom in PNP ligand enables one to obtain complexes with η¹ -coordinated P₄ molecule, which indicates a crucial role of N-H bond in transformation of white phosphorus tetrahedron. Additionally, complex 4 can readily be functionalized by means of the reaction with Ph₂ PCl leading to the formation of a new complex bearing unique P₉ -ligand. The obtained results provide opportunities for facile construction of new polyphosphorus ligands in the coordination sphere of transition metal complexes.