The formation and isolation of benzisothiazole rings from the reactions of oxime-thiophenolate ligands

The reaction of [Ni(eftp)] (eftp = N, N-ethylene(6-formyl-4-methyliminatothiophenolato)] with hydroxylamine hydrochloride in the presence of potassium acetate in MeOH resulted in the formation of [Ni(L)(2)], L = 2-mercapto-5-methyl-3-({2-[(5-methylbenzo[d]isothiazol-7-ylmethylene)-amino]-ethylimino)-methyl)-benzonitrile. A single-crystal X-ray diffraction structural determination showed that the oxime groups of the proposed new binucleating ligand had reacted to produce a nitrite and an isothiazole ring, while two ligand molecules combined with one Ni(II) ion to form a new complex with a cis-S2N2 square-planar geometry. Also, the reaction of 2,6-diformyl-4-methylphenyl disulfide with hydroxylamine in MeCN resulted in the synthesis of 5-methyl-2-oxybenzo[d]isothiazole-7-carbaldehyde oxime, where an isothiazole ring had formed via the cleavage of the disulfide bond. Again, a single-crystal X-ray diffraction study confirmed the presence of a benzisothiazole product. (c) 2006 Elsevier B.V. All rights reserved.