2015 Volume 73 Issue 9 Pages 885-894
Dicoordinate phosphorus-centered radical (phosphinyl radical) is a fascinating reactive intermediate in phosphorus chemistry because it has a bifunctional phosphorus center owing to an unpaired electron and a lone pair. I report herein synthesis, structure, properties, and various reactions of the first stable dialkylphosphinyl radical, 2,2,5,5-tetrakis(trimethylsilyl)-1-phosphacyclopentane-1-yl (8), which is monomeric both in solution and in the solid state. Palladium complex bearing two phosphinyl radicals as ligands (24) is also synthesized by the ligand exchange reaction of tetrakis(trimethylphosphine)palladium with two equivalents of radical 8. Complex 24 shows unique phosphorus-palladium double bond character. Antimony and bismuth analogues of phosphinyl radicals are elusive species but are thought to be important intermediates. We have succeeded in the observation of antimony- and bismuth-centered radicals (30 and 31) as persistent species in solution by the dissociation of the corresponding dimer.
