Modulation of intermolecular exchange interaction in organic radical based compounds: Magneto-structural analysis of phenol and imidazolium substituted oxoverdazyl radicals

The synthesis of two oxoverdazyls based compounds, the 1,5-dimethyl-3-(2′-hydroxyphenyl)-6-oxoverdazyl 1 and the perchlorate salt of 1,5-dimethyl-3-(2′-imidazolium)-6-oxoverdazyl 2 are reported. The structural analysis of 1 reveals that radicals are closely packed in regular columns by way of π-stacking. In contrast, the packing in 2 is definitely influenced by the protonation state of the radical substituent and shows strong lateral staggering of the organic radicals. The organisation in the solid state strongly influences the intermolecular exchange interaction between π-stacked radicals which goes from J = −113 cm−1 (H = −J∑SiSi+1) in 1 to J = −1.0 cm−1 and J′ = −0.67 cm−1 in 2.

The crystal packing of two oxoverdazyl radicals is so different that the intermolecular exchange interaction between the radical varies by two orders of magnitude.Figure optionsDownload as PowerPoint slide