Cyclic Trimeric Triradical Indium(III) Complex with a Bridging Tetrazine Ligand in the Radical Anion State

A cyclic triradical metal complex is constructed from bridging 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) radical anions and indium cations. Molecular and crystal structures of the synthesized compound are determined by the single crystal X-ray diffraction analysis. According to the magnetochemical studies, strong antiferromagnetic coupling between unpaired electrons of tetrazine radical anions stabilizes the ground doublet spin state in the trinuclear indium complex obtained, with the quadruplet state being thermally available.