Design And Synthesis Of 4f-2p Complexes And Single Molecular Magnets

This work focuses on the popular research of Ln-radical complexes and single molecular magnets (SMMs). By using three synthesized nitronyl nitroxide radicals (two of which are the first reported) as ligands, one SMM and nineteen new metal--radical complexes (fifteen are 4f-2p systems and four are 4f-3d systems) have been obtained. The structures of these complexes have been determined by X-ray crystal-lographic methods and characterized by element analyses, IR, Uv-visble, fluorescence spectra, ESR, electro-chemistry and DC/AC magnetic susceptibility.1. Three nitronyl nitroxide radicals have been synthesized, one of which has been determined by X-ray crystallographic methods. They have been characterized IR, Uv-visble, ESR and electro-chemistry.2. Using the radical NIT-5-Br-3Py as ligand, fourteen complexes have been synthesized. The molecular structures are dimers, and their magnetic properties are studied. Among them the complex [Tb(hfac)3(NIT-5-Br-3Py)]2 is the second SMM containing two lanthanide ions and two radicals, which has a significant higher barrier than the first SMM; In addition the Dy complex preliminarily displays SMM behavior; To the Gd complex, the fitting result of the magnetic susceptibility shows two different magnetic interactions between Gd(III) ion and NIT-5-Br-3Py in one complex:a weak ferromagnetic interaction through the N-0 group, and a much weaker antiferromagnetic interaction through pyridine ring. To our knowledge, it is firstly observed that there are two different kinds of magnetic interactions (ferromagnetic and antiferromagnetic) between Gd(III) and free radical because of the different bridging mode (N-0 group and pyridine ring).3. Using the radical NIT-Ph-O-Ph-O-CH3 as ligand, four 4f-2p metal-radical complexes have been obtained and characterized structurally and magnetically. The structures of the Eu and Tb complexes are all one-dimensional chains, and the Ho and Yb complexes are all monometallic two-spin systems. Magnetic studies reveal that there are weak ferromagnetic interactions between the paramagnetic ions in the Eu and Tb complexes and weak antiferromagnetic interactions between the paramagnetic ions in the Ho and Yb complexes.4. Using the radical NIT-Ph-O-CH2-CH2-Br as ligand, two complexes are obtained, and characterized structurally and magnetically. The Tm complex is monometallic tri-spin systems, and the Mn complex contains one dimmer and one isolated radical. Magnetic studies reveal that there are weak antiferromagnetic interactions between two Mn(Ⅱ) ions in the Mn complex.