Synthesis and characterization of novel nitroxide organometallic Fischer-type carbene complexes

Reactions of 4-amino TEMPO with alkynylmethoxy Fischer type carbene complexes lead to unknown transition organometallic nitroxide spin labels. According to the temperature and the nature of the aromatic group of the initial alkynyl carbene, Michael adducts and aminolysis products were obtained in various proportions. The reaction was extended to ferrocenyl carbene complexes to obtain novel organometallic spin systems containing two kinds of redox units. Their constitution is in agreement with IR, elemental analysis and mass spectrometry. Single X-ray diffraction has confirmed the molecular structure of the complexes and has showed the existence of intra and intermolecular hydrogen bonds. These air-stable paramagnetic carbenes have interesting redox behaviours and paramagnetic properties.