α‐Radical Phosphines: Synthesis, Structure, and Reactivity

A series of phosphines featuring a persistent radical were synthesized in two steps by condensation of dialkyl‐/diarylchlorophosphines with stable cyclic (alkyl)(amino)carbenes (cAACs) followed by one‐electron reduction of the corresponding cationic intermediates. Structural, spectroscopic, and computational data indicate that the spin density in these phosphines is mainly localized on the original carbene carbon from the cAAC fragment; thus, it remains in the α‐position with respect to the central phosphorus atom. The potential of these α‐radical phosphines to serve as spin‐labeled ligands is demonstrated through the preparation of several AuI derivatives, which were also structurally characterized by single‐crystal X‐ray diffraction. Da ist das Radikal! Eine Reihe von Phosphan‐α‐Radikalen wurde ausgehend von cyclischen Alkyl(amino)carbenen synthetisiert, strukturanalytisch charakterisiert und an Gold(I) koordiniert. Dichtefunktionalrechnungen zufolge ist die Spindichte für Phosphanliganden wie Goldkomplexe über das Carben‐π‐System delokalisiert, mit Schwerpunkt auf dem vormaligen Carben‐Kohlenstoffatom.