A prototype hybrid 7 pi quinone-fused 1,3,2-dithiazolyl radical

Reaction of 1,4-naphthoquinone and SNSMF6 (M = As, Sb) in SO2 solution in a 1 : 2 molar ratio led to the naphthoquinone fused 1,3,2-dithiazolylium salts, 3MF(6) quantitatively by multinuclear NMR (87% isolated yield of 3SbF(6)) via the cycloaddition and oxidative dehydrogenation chemistry of SNS+ with formation of NH4SbF6 and S-8. The product 3SbF(6) was fully characterized by IR, Raman, multinuclear {H-1, C-13, N-14} NMR, elemental analysis, cyclic voltammetry and single crystal X-ray crystallography. The reduction of 3SbF(6) with ferrocene (Cp2Fe) in refluxing acetonitrile (CH3CN) led to the first isolation of a fused quinone-thiazyl radical, 3(center dot) in 73% yield. The prototype hybrid quinone-thiazyl radical 3(center dot) was fully characterized by IR, Raman microscopy, EI-MS, elemental analysis, solution and solid state EPR, magnetic susceptibility (2-370 K) and was found to form pi*-pi* dimers in the solid state as determined by single crystal X-ray crystallography. Furthermore, the thermal decomposition of 3(center dot) led to a novel quinone-fused 1,2,3,4-tetrathiine, 10 (x = 2) and the known 1,2,5-thiadiazole, 11. The energetics of the cycloadditon and oxidative dehydrogenation chemistry of SNS+ and 1,4-naphthoquinone leading to 3SbF(6) were estimated in the gas phase and SO2 solution by DFT calculations (PBE0/6-311G(d)) and lattice enthalpies obtained by the volume based thermodynamic (VBT) approach in the solid state. The gas phase ion energetics (ionization potential (IP) and electron affinity (EA)) of 3(center dot) are compared to related 1,3,2- and 1,2,3-dithiazolyl radicals.