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RESEARCH PRODUCT

Investigations on organoantimony compounds XI. Triorganoantimony(V) compounds containing potentially tridentate ligands

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Triorganoantimony(V) compounds of the types RSbVL, in which R = Me or Ph, and L represents a potentially tridentate dianionic Schiff base ligand of the ONO or SNO type, have been synthesized and investigated by spectroscopic (UV, IR, PMR) methods. Molecular weight determinations in benzene reveal the monomeric nature of these compounds. The free ligands, HL, used in this study are:,′-(methylidynenitrilo)diphenol (HSab), -(o-hydroxyphenyl)benzothiazoline (H-Sat), -(o_hydroxyanilino)crotonophenone (HBah), 4-(o-hydroxyphenylimino)--pentanone (HAah) and -acetonyl--methylbenzothiazoline (HAat). Both the UV and the IR data suggest hexacoordinate molecular structures for the complexes RSbL in which the L- ligand coordinates to the RSbV moiety as a planar tridentate ligand. PMR spectroscopy indicates that at room temperature in solution the hexacoordinate organoantimony(V) compounds MeSbSab and MeSbSat are stereochemically non-rigid. An X-ray structure determination has revealed that in the crystalline state the antimony atom in MeSbSab possesses a distorted octahedral geometry. Complexes of the type RSbVAat (R = Me, Ph) could not be isolated as a result of their spontaneous decomposition into triorganostibines, RSbIII, and -acetyl--methyl-4H-1,4-benzothiazine. © 1974.