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

(C5Me5)(3)Sm reacts with the free radical 2,2,6,6-tetramethylpiperidinyl-1-oxy (TMPO) to form (C5Me5)(2) and the per nitroxide [(eta (1)-ONC5H6Me4)(2)Sm(mu-eta (1) : eta (2)-ON-C5H6Me4)](2).