Isolable Diphosphorus-Centered Radical Anion and Diradical Dianion

Abstract

Two salts containing diphosphorus-centered radical anion <b>1</b>^•– and diradical dianion <b>1</b>^2–•• were obtained by one- and two-electron reductions of an indenofluorene-bridging diphosphaalkene (<b>1</b>) with K and KC₈, respectively. The salts have been characterized by electron paramagnetic resonance (EPR) spectroscopy, UV–vis absorption spectroscopy, and single-crystal X-ray diffraction analysis. EPR spectroscopy and theoretical calculations reveal that the spin density of the radicals mainly resides on the phosphorus atoms, and <b>1</b>^2–•• has an open-shell singlet ground state. <b>1</b>^•– and <b>1</b>^2–•• represent the first isolable and structurally characterized diphosphorus-centered radical anion and dianion