New Paramagnetic Thiazyl Ligands and their Coordination Complexes
A series of 1,2,3-dithiazolyl radicals have been prepared as spin-bearing radical ligands for coordination to paramagnetic transition metal and lanthanide ions to afford both interesting magnetic and potential conductive properties. The novel syntheses and full characterization of the ligands are described with the electronic properties investigated by both solution & solid-state EPR and cyclic voltammetry. The ligand structures are characterized by X-ray crystallography and the magnetic properties investigated. The ligands described herein represent the first reported 1,2,3-dithiazolyl radical ligands to coordinate to paramagnetic transition metal or lanthanide ion(s). The 1,2,3-dithiazoyl ligands described have been used to prepare a number of metal complexes and the structures have been fully characterized by X-ray crystallography. A diverse range of complexes including monomers, trimers and polymers have been synthesized and characterized. The solid-state and solution magnetic properties of the metal complexes have been investigated using a range of appropriate instrumental techniques, and are reported. The chelating properties of the 1,2,3-dithiazolyl ligands described are via an unprecedented motif. A para-naphthoquinone backbone is utilized with the fused 1,2,3dithiazolyl heterocyclic ring. The coordination geometry between the nitrogen atom and the quinone oxygen(s) allows for the variety of complexes reported, including the design objective of a polymeric paramagnetic coordination complex. A series of 1,2,5-thiadiazolyl radical anions have been prepared as spin-bearing radical ligands for the coordination to paramagnetic transition metal and lanthanide ions to enable both interesting magnetic and conductive properties. The syntheses and full characterizations are described with the electronic properties investigated by solution EPR and cyclic voltammetry. The ligand structures are characterized by X-ray crystallography and both the magnetic properties and conductivity (including Extended Hückel Theory calculations) are investigated and reported. A series of novel fluorinated 1,2,5-thiadiazole closed shell neutral ligands have been prepared and characterized. The radical anion is studied in situ by EPR. All materials generated in the synthesis were sent to the National Cancer Institute (USA) for collaboration involving clinical cancer inhibition studies and the results are reported.