Several new cobalt(III) complexes incorporating 4,4,5,5-tetramethyl-2-(3-or 4-pyridyl)imidazolin-1-oxyl 3-oxide (NITnpy) (n = 3 or 4) or 4,4,5,5-tetramethyl-2-(3-or 4-pyridyl)-imidazolin-1-oxyl (IMnpy) have been prepared. The X-ray crystallographic analyses and the spectroscopic investigations have revealed that the nitronyl or imino nitroxides with the radical character are bound through the pyridyl-N atom to a Co III center. There are some influences from the radical unpaired electron toward the Co III complex moiety and those from the coordination of the Co III ion toward the

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Diamagnetic lanthanide(III) complexes with an imino nitroxide radical IM2py [2‐(2′‐pyridyl)‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazol‐1‐oxyl], [Ln(hfac)3(IM2py)] (Ln = Y and Lu; hfac = hexafluoroacetylacetonate), exhibit 1H NMR chemical shifts for the pyridyl protons of the coordinated IM2py suggesting it behaves as if it were diamagnetic. To a series of paramagnetic lanthanide complexes of this type, the structural analyses of the lanthanide induced shifts (LIS) of the hfac 3‐proton and pyridyl protons in IM2py were successfully applied, showing not only the diamagnetic behaviour of the pyridyl protons in the IM2py group, but also the dominant dipolar contribution and isostructural nature with apparent or effective axial symmetry in solution irrespective of the asymmetry in the solid state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The complex cation in the title compound, [Co(C5H7O2)2(C9H20N2)(C18H15P)]PF6·CH2Cl2, is the first example of a CoIII complex in which a trans configuration for the coordinated monodentate phosphine and amine ligands has been confirmed by X‐ray analysis. Owing to the large steric bulkiness of the axial PPh3 ligands influencing the interaction with the equatorial acetyl­acetonate ligands, the acetyl­acetonate planes bend away considerably from the PPh3 ligands.