Stabilisation of tetrabromo- and tetrachlorosemiquinone (bromanil and chloranil) anion radicals in crystals

• DOI: 10.1039/c1ce05513e
• Publication Date: 2011-06-25T08:31:25Z
• Authors: Krešimir Molčanov; Biserka Kojić-Prodić; Darko Babić; Dijana Žilić; Boris Rakvin
• Keywords: Unpaired electron; Semiquinone; Radical ion

Crystal structures of alkali salts tetrahaolgenosemiquinone anion radical acetone solvates and their solvent-free are determined. p-Semiquinone reveals enhanced aromaticity the ring compared to quinone. A pair π-stacked (p-semiquinone) rings occurs in crystal potassium rubidium tetrachlorosemiquinone tetrabromo analogue. The centroid separation distances about 3.2 Å carbon–carbon contacts between contiguous 0.3 shorter than sum van der Waals radii. spin-coupling two unpaired electrons (forming a stacked dimer) correlates with diamagnetic property crystals. Magnetic properties were examined by electron paramagnetic resonance spectroscopy.