Chelated compounds and derivative of β-alkoxycarbonylalkyltin chlorides — 5-arylazo-8-quinolinolates, alizarinates, and thiocyanate: preparation and spectroscopic studies

Abstract

Complex formation with chelating ligands like 5-phenylazo-8-quinolinol, 5-(2I-carboxyphenylazo)-8-quinolinol, 1,2-dihydroxyanthraquinone (i.e., alizarin), and 1-nitroso-2-naphthol is due to nucleophilic attack on tin of the β-alkoxycarbonylalkyltin chlorides (a unique class of PVC stabilizer intermediates) with the subsequent elimination of hydrogen chloride. A number of complexes of the types R2SnL2, RSnL2Cl, R2SnLCl, R2Sn(LIHI)2, R2SnLII, and RSnLIICl (where R = CH3OCOCH2CH2—, C4H9OCOCH2CH2—, and CH3OCOCH(CH3)CH2—; LH = 5-phenylazo-8-quinolinol, 1-nitroso-2-naphthol; LIHHI = 5-(21-carboxyphenylazo)-8-quinolinol; and LIIH2 = 1,2-dihydroxyanthraquinone) and a thiocyanate derivative viz. (CH3OCOCH2CH2)2Sn(SCN)2 have been prepared. 5-Arylazo-8-quinolinols exhibit azo–hydrazone tautomeric equilibria but their complexes exist only in the azo form. β-Alkoxycarbonylethyltin alizarinates are somewhat different from other complexes. In these complexes two hydroxyl groups of alizarin have been utilised in complex formation, moreover, one of the two carbonyl groups of alizarin also remains involved in coordination to tin. In (CH3OCOCH2CH2)2Sn(SCN)2, the thiocyanate group is possibly linked to tin atom through nitrogen. All the complexes and the thiocyanate derivative have been characterised by elemental analyses, electronic, ir, and 1H nmr spectra. Possible structural features of the compounds are discussed.