Structural characterization of 1,3-propanedithiols that feature carboxylic acids: Homologues of mercury chelating agents

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• 作者：Wesley Sattler ; Joshua H. Palmer ; Christy C. Bridges ; Lucy Joshee ; Rudolfs K. Zalups ; Gerard Parkin
• 关键词：Mercury ; Thiolate ; Chelating agent
• 刊名：Polyhedron
• 出版年：2013
• 出版时间：12 November, 2013
• 年：2013
• 卷：64
• 期：Complete
• 页码：268-279
• 全文大小：2515 K

文摘

The molecular structures of a series of 1,3-propanedithiols that contain carboxylic acid groups, namely rac- and meso-2,4-dimercaptoglutaric acid (H₄DMGA) and 2-carboxy-1,3-propanedithiol (H₃DMCP), have been determined by X-ray diffraction. Each compound exhibits two centrosymmetric intermolecular hydrogen bonding interactions between pairs of carboxylic acid groups, which result in a dimeric structure for H₃DMCP and a polymeric tape-like structure for rac- and meso-H₄DMGA. Significantly, the hydrogen bonding motifs observed for rac- and meso-H₄DMGA are very different to those observed for the 1,2-dithiol, rac-2,3-dimercaptosuccinic acid (rac-H₄DMSA), in which the two oxygen atoms of each carboxylic acid group hydrogen bond to two different carboxylic acid groups, thereby resulting in a hydrogen bonded sheet-like structure rather than a tape. Density functional theory calculations indicate that 1,3-dithiolate coordination to mercury results in larger S-Hg-S bond angles than does 1,2-dithiolate coordination, but these angles are far from linear. As such, ¦Ê²-S₂ coordination of these dithiolate ligands is expected to be associated with mercury coordination numbers of greater than two. In vivo studies demonstrate that both rac-H₄DMGA and H₃DMCP reduce the renal burden of mercury in rats, although the compounds are not as effective as either 2,3-dimercaptopropane-1-sulfonic acid (H₃DMPS) or meso-H₄DMSA.