| A series of 1,2,3,5-dithiadiazolyl radicals have been prepared as spin-bearing ligands for enabling magnetic exchange with coordinated paramagnetic transition metal ions. The electronic properties of the ligands have been investigated by solution EPR and cyclic voltammetry, and the structures characterized by X-ray crystallography wherever possible. The ligands described represent the first 1,2,3,5-dithiadiazolyl radicals to bond to transition metal ions via nitrogen atom coordination, without metal insertion or interaction with the sulfur-sulfur bond of the thiazyl ring.;When the aryl group belonging to the 1,2,3,5-dithiadiazolyl radical possesses a nitrogen atom donor in an appropriate ring position (e.g. 2-pyridyl), the molecule behaves as a ligand that chelates a transition metal ion in an η2 fashion. In the absence of ligand dimerization, ferromagnetic or antiferromagnetic coupling between the radical ligand and the metal ion can be rationalized based on a spin topology model of the molecule.;The tendency of 1,2,3,5-dithiadiazolyl radicals to associate via close π-stacking contacts in the solid state generates diamagnetic dimers. Consequently, in coordination complexes wherein close π-stacking contacts are observed between ligands in the solid state, magnetic coupling of the ligand with a coordinated transition metal ion is not observed. In the case of the metal complexes of 4-(2'-pyridyl)-1,2,3,5-dithiadiazolyl that associate in the solid state, the thermodynamic parameters of the monomer/dimer equilibria in solution have been determined using quantitative UV-VIS spectroscopy. Thus, the solution magnetic properties of the same complexes have been interpreted in light of the dimerization equilibrium and reveal ferromagnetic or antiferromagnetic coupling based on the expected spin topology of the monomer.;When the aryl group of the 1,2,3,5-dithiadiazolyl radical bears a nitrile substituent, certain intermolecular packing interactions can be selectively targeted. The packing interactions can lead to the formation of structurally ordered 1-dimensional chains in the solid state. Dimerization and the absence of any intermolecular magnetic exchange pathways between metal complexes, however, restricts the magnetic properties of molecular chains generating paramagnetic-only species.;The 1,2,3,5-dithiadiazoyl ligands described have been used to prepare a number of metal complexes, which have been fully characterized by X-ray crystallography. The solid state and solution magnetic properties of the metal complexes have been investigated using a range of instrumental techniques, where appropriate. The electronic structure of several metal complexes has also been investigated using cyclic voltammetry, provided that the monomeric species in solution can be probed.;4-(2-Cyano-furyl-5)-1,2,3,5-dithiadiazolyl enables the unprecedented and unanticipated capability to coordinate transition metal ions in a monodentate η 1 fashion via the nitrogen atoms of the thiazyl ring. This leads to the formation of 1-dimensional coordination polymers in the solid state. |
