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

摘要

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, 3MF6 quantitatively by multinuclear NMR (87% isolated yield of 3SbF6) via the cycloaddition and oxidative dehydrogenation chemistry of SNS+ with formation of NH 4SbF6 and S8. The product 3SbF6 was fully characterized by IR, Raman, multinuclear {1H, 13C, 14N} NMR, elemental analysis, cyclic voltammetry and single crystal X-ray crystallography. The reduction of 3SbF6 with ferrocene (Cp 2Fe) in refluxing acetonitrile (CH3CN) led to the first isolation of a fused quinone-thiazyl radical, 3 in 73% yield. The prototype hybrid quinone-thiazyl radical 3 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 π*-π* dimers in the solid state as determined by single crystal X-ray crystallography. Furthermore, the thermal decomposition of 3 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 3SbF6 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 are compared to related 1, 3, 2- and 1, 2, 3-dithiazolyl radicals.