Synthesis and Characterization of Novel Multidentate 1,2,3,5- Dithiadiazolyl Radical Ligands with Potential Luminescent and Magnetic Applications

Novel, multidentate (denticity greater than two) 1,2,3,5-dithiadiazolyl radical ligands have been synthesized and characterized. The 4-(2',2''-bipyrid-6'-yl)-1,2,3,5- dithiadiazolyl (bipyDTDA) radical ligand has been characterized via X-ray crystallography and displays cis-cofacial dimerization in the solid state. BipyDTDA features a tridentate nitrogen coordination pocket and was successfully coordinated to Ln(III) metal centers including Ce(III), Pr(III) and Dy(III). The complexes above are structurally interesting in terms of Ln-Thiazyl compounds as they are isostructural throughout most of the lanthanide series. An additional undimerized complex SbCl3(bipyDTDA) has also been synthesized which contains contacts that imply a potential pathway for intermolecular magnetic coupling. A second DTDA ligand 6,6'-bis-1,2,3,5-dithiadiazolyl-2,2'-bipyridine (bisDTDAbipy) has been prepared and characterized via DART-MS. The EPR spectrum for this diradical species exhibits a five-line pattern consistent with two non-interacting radical centers each with coupling to two equivalent 14N nuclei. Coordination of bisDTDAbipy has yet to be achieved.