The tetramethylpiperidinyl-1-oxide anion (TMPO-) as a ligand in lanthanide chemistry: synthesis of the per(TMPO-) complex [(ONC5H6Me4)2Sm(mu-ONC5H6Me4)]2.

(C5Me5)3Sm reacts with the free radical 2,2,6,6-tetramethylpiperidinyl-1-oxy (TMPO) to form (C5Me5)2 and the per nitroxide [(eta 1-ONC5H6Me4)2Sm(mu-eta 1:eta 2-ONC5H6Me4)]2.