Carboxylates, structural chemistry oxalates

Somewhat surprisingly, maltol (2-methyl-3-hydroxy-4-pyrone), an aromatic analogue to a-hydroxy carboxylic acids, shows little inclination toward formation of dimeric complexes. Rather, the chemistry is more in parallel with that of oxalate, and an x-ray structure of the bismaltolato complex [25] shows a cis octahedral coordination similar to that found for the oxalate complex. Under mildly acidic to moderately basic solution, the major complexes are mono- and bisligand derivatives. The corresponding vanadium chemical shifts are -509 and -496 ppm, respectively [25,26], The closely related amines, 2-methyl-3-hydroxy-4-pyridinone and its N-... 

R. Tacke, O. Dannappel, M. Muhleisen, Syntheses, Structures, and Properties of Molecular Si-Silicates Containing Bidentate 1,2-Diolato(2-) Ligands Derived from a-Hydroxy-carboxylic Acids, Acetohydroximic Acid, and Oxalic Acid New Results in the Chemistry of Pentacoordinate Silicon", in Organosilicon Chemistry II From Molecules to Materials (Eds. N. Auner, J. Weis), VCH, Weinheim, 1996, pp. All-446. 

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