1,2,3,5-Dithiadiazolyl Radical Ligands with Sulfur-Containing Heterocyclic R-groups and their Coordination Complexes

Abstract

This thesis presents the first 1,2,3,5-dithiadiazolyl (DTDA) radicals with a sulfur-containing moiety outside the DTDA ring. Three new DTDA-based ligands were synthesized and characterized along with several of their lanthanide and transition metal complexes. The three novel radicals are 4-(3ʹ-benzoisothiazolyl)-1,2,3,5-dithiadiazolyl (bitaDTDA), 4-(5-methyl-3ʹ-benzoisothiazolyl)-1,2,3,5-dithiadiazolyl (bitaplusDTDA) and 4-(benzothiazol-2ʹ-yl)-1,2,3,5-dithiadiazolyl (betaDTDA). BitaDTDA has been coordinated to three lanthanide ions; La(III), Gd(III) and Dy(III). BitaplusDTDA has been coordinated to Mn(II) and Dy(III). BetaDTDA has been coordinated to Mn(II), Fe(II), La(III), Pr(III), Gd(III), Tb(III), Dy(III) and Er(III). Almost all the complexes and radicals presented in this thesis dimerize in the solid state. Also described in this thesis are three Dy(III) single molecule magnets with energy barriers of 84 K, 85 K and 126 K. The coordination of La(III) to bitaDTDA resulted in the first ten (10) coordinate Ln-DTDA complex of a DTDA dimer, such that the Ln(III) is coordinated to both the ligands of the dimer. Three polymorphs of La(hfac)3(betaDTDA)2 have been identified and characterized. Over ten new compounds have been synthesized and characterized.