Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
The cover picture shows the array of colors observed in the synthesis of the long-lived phosphorus radicals [Mes*MeP−PMes*]. (3; Mes*=2,4,6-tBu3C6H3). These colors were obtained by layering a colorless solution of the electron-rich tetrakis(dimethylamino)ethylene (2) in acetonitrile onto a yellow solution of the phosphenium salt [Mes*MeP=PMes*]+[O3SCF3]− (1) in acetonitrile. An immediate intense green color characteristic of solute 3 formed at the phase boundary. At the same time orange-red crystals of 3 appeared and deposited on the walls of the container. The red color denotes the formation of the radical cation [(Me2N)3C2].+. More about this reaction, which has allowed the first isolation of diphosphanyl radicals, is described by Geoffroy, Grützmacher, and co-workers on page 723 ff.