1‑Phenyl-3-(pyrid-2-yl)benzo[e][1,2,4]triazinyl: The First “Blatter Radical” for Coordination Chemistry

A neutral air- and moisture-stable N,N′-chelating radical ligand, 1-phenyl-3-(pyrid-2-yl)­benzo­[e]­[1,2,4]­triazinyl (1) was synthesized and characterized by electron paramagnetic resonance spectroscopy, X-ray crystallography, and magnetic measurements. Subsequent reaction of 1 with Cu­(hfac)2·2H2O (hfac = hexafluoroacetylacetonate) under ambient conditions afforded the coordination complex Cu­(1)­(hfac)2 in which the radical binds to the metal in a bidentate fashion. Magnetic susceptibility data collected from 1.8 to 300 K indicate a strong ferromagnetic metal-radical interaction in the complex and weak antiferromagnetic radical···radical interactions between the Cu­(1)­(hfac)2 units. Detailed computational investigations support this assignment. Radical 1 is a new addition to the growing library of 1,2,4-triazinyl radicals and the first member of this family of paramagnetic species synthesized specifically for coordination purposes.