Nickel(II) complex with optically active (3S)-3-hydroxyaminocaran-4-one E-oxime and its oxidation into a complex with nitroxyl radicals

Ni(II) chelate with (3S)-3-hydroxyaniinocaran-4-one E-oxime (H2L) of composition Ni(HL)(2) . 2H(2)O was synthesized. The compound is diamagnetic, which suggests the square-planar structure of a NiN4 coordination unit. The electronic absorption spectroscopy and EPR methods were used to study its oxidative dehydrogenation in benzene resulting in a compound containing nitroxyl radicals Ni(HL.)(2) and exhibiting strong antiferromagnetic exchange coupling of unpaired electrons of the radicals. An intermediate paramagnetic form Ni(HL)(HL.) was discovered by the EPR method.