Physical properties of mononuclear organoeuropium sandwich complexes ligated by cyclooctatetraene and bis(trimethylsilyl)cyclooctatetraene

Mononuclear divalent europium (Eu) complexes with COT (1) and COT″ (2), synthesized in a liquid ammonia solution, emit red and orange-red light, respectively, with large differences in quantum yield (Φf (1) = 2.4%; Φf (2) = 21%).