C2‑Symmetric P,N Ligands Derived from Carborane-Based Diphosphetanes: Synthesis and Coordination Chemistry

Racemic carborane-based bisphosphanes were obtained by dismutation reactions between a carborane-based diphosphetane and diaryl dichalogenides. NMR spectroscopic and theoretical studies revealed a two-step mechanism explaining the high stereoselectivity of these reactions. The coordination chemistry of the multidentate P,N ligands 6c and 6d in copper­(I) and silver­(I) complexes was studied. While 6d acted exclusively as tetradentate ligand, 6c showed either tridentate or tetradentate coordination depending on the metal and the counterion.