Noninnocent Behavior of Bidentate Amidophosphido [NP]2– Ligands upon Coordination to Copper

The synthesis and preliminary coordination chemistry of two new redox-active bidentate ligands containing amido and phosphido donors are described. Treatment of the [RNP]2– (R = Ph, 2,4,6-trimethylphenyl) ligands with CuCl2 and PMe3 results in a dimeric copper­(I) P–P coupled product via ligand oxidation. The intermediate of this reaction is proposed to involve a ligand radical generated via oxidation of the [RNP]2– ligand by copper­(II), and the existence of such an intermediate is probed using computational methods. Significant radical character on the phosphorus atoms of the alleged [RNP]•–/copper­(I) intermediate leads to P–P radical coupling.