New bis-o-benzosemiquinonato tin(IV) complexes

New bis-o-benzosemiquinonato tin(IV) complexes (3,6-SQ)2SnCl2, (3,6-SQ)2SnBr2 and (3,6-SQ)2SnPh2 (3,6-SQ is radical-anion 3,6-di-tert-butyl-o-benzosemiquinone) were synthesized by different methods. The reaction of tin(IV) catecholates (3,6-Cat)SnX2·2THF (Х = Cl, Br) with nitrogen(IV) oxide leads to EPR-active six-coordinated mono-o-benzosemiquinonato complexes of (3,6-SQ)SnX2(NO2)·THF type which undergo symmetrization to the corresponding diradical bis-o-benzosemiquinonato species (3,6-SQ)2SnX2. Diphenyltin(IV) catecholate (3,6-Cat)SnPh2·THF reacts with Br2, I2 and NO2 to give five-coordinated species (3,6-SQ)SnPh2X (X = Br, I, NO2) which transform to bis-(o-benzosemiquinonato)diphenyltin(IV) (3,6-SQ)2SnPh2. The molecular structures of (3,6-SQ)2SnBr2 and (3,6-SQ)2SnPh2 were determined by X-ray analysis.