TRANSITION-METAL COMPLEXES OF NITROXIDE R ADICALS - PALLADIUM, PLATINUM, PENTAMETHYLCYCLOPENTADIENYL RHODIUM AND IRIDIUM COMPLEXES, AND ALPHA-AMINOCARBOXYLATE COMPLEXES WITH DERIVATIVES OF 2,5-DIHYDROIMIDAZOLE-1-OXYLS

2,5-Dihydroimidazoline-1-oxyl radicals I, II with imino substituents c oordinate to Pd(II) and Pt(II) complexes with formation of the N,N che late complexes 1 - 6. With oxygen containing substituents either monod entate N-coordination to give 8 or N,O chelate formation to give 9 tak es place, depending on the position of the oxygen atom relative to the ring nitrogen atom. With radicals III that also have the second ring nitrogen atom oxidized and the Rh(III) or Ir(III) complexes [CpMCl2]( 2) the O,O chelates 11-13 could be obtained, while with Na2PdCl4 the h eterocycle was destroyed with formation of a N,N chelate complex 10 of an alpha-nitrosooxime ligand. The orthopalladated 2,2,5,5 tetramethyl -4-phenyl-2,5-dihydroimidazoline-1-oxyl complex 7a reacts with several alpha-amino acidates under splitting of the dichloro bridge with form ation of the C,N/N,O-bis-chelate complexes 7b-f. The molecular structu res of 2 and 10 were determined by X-ray diffraction.