Abstract
Transformations of bis-α-benzyldioximate iron(II) dichloroclathrochelate FeBd2(Cl2Gm) (BF)2 (where Bd2– and Cl2Gm2– are -benzyldioxime and dichloroglyoxime dianions, respectively) in the system DMSO – FeII – H2O2 – H2O predominantly gave macrobicyclic products resulted from methylation of -dioximate chelate fragments of its cage framework. Both the nature and yields of these products depend on the concentration of H2O2: at its low concentrations a degree of conversion of such dichloroclathrochelate precursor is rather small, and two main macrobicyclic products are the methylchloroglyoximate complex FeBd2(ClGmCH3)(BF)2 and the clathrochelate FeBd2(ClGm(O2SCH3))(BF)2 with methylsulfonyl ribbed substituent, whereas at high H2O2 concentrations the yield of the clathrochelate products of freeradical methylation reaction increases and this process becomes dominating over nucleophilic substitution: the initial clathrochelate products FeBd2(ClGmCH3)(BF)2 and FeBd2Dm(BF)2 (where Dm2– is dimethylglyoxime dianion), resulted from the subsequent attacks by methyl radicals on the N=C–Cl fragments of a macrobicyclic tris-dioximate ligand, undergo further methylation of the azomethine fragment giving the oximatohydroxylamine cage complex. The obtained diamagnetic low-spin iron(II) complexes were characterized using TLC, 1H, 11B, 19F, 15N and 13C{1H} NMR spectra, and by X-ray diffraction.
Keywords: α-dioximes, clathrochelates, Fenton reaction, iron complexes, ligand reactivity, macrocyclic compounds.
Graphical Abstract
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