An aromatic schiff base stabilised as a coordinated enol iminium zwitterion by complex formation with a series of divalent metal ions |
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| Authors: | John M. Bellerby John H. Morris W.Ewen Smith |
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| Affiliation: | Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, U.K. |
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| Abstract: | The Schiff base N-(2-hydroxy-3-carboxy-1-naphthylidine)-4-methyl-2-sulphonic acid aniline (bonsaH3) has been found to react with a range of divalent metal ions (Mg2+, Mn2+, Co2+, Ni2+ and Zn2+ and UO22+ to give red-yellow insoluble complexes (bonsaH)m(H2O)n. The solid state diffuse reflectance spectra of all the complexes have an intense visible band at ca. 470 nm. This fact, together with evidence from infrared spectra and room-temperature magnetic-moment measurements, suggests that in all cases the ligand is coordinated to the metal ion in the solid state in the enol-iminium zwitterionic form. The 1H NMR spectra of the Mg2+ and Zn2+ complexes in DMSO-d6 indicate that a different structure is adopted in this solvent. Comparisons with the spectra of bonsa-H3 and (bonsa-H2)K·H2O suggest that the solution structure is that of an enol-imine. |
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| Keywords: | Author to whom correspondence should be addressed. |
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