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Carbohydrate Chelation in Neutral Aqueous Solution: The threo ‐Tetritolato‐Pd 4 Butterfly Motif
Author(s) -
Allscher Thorsten,
Klüfers Peter
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201100979
Subject(s) - chemistry , aqueous solution , chelation , denticity , palladium , stereochemistry , crystallography , medicinal chemistry , organic chemistry , crystal structure , catalysis
Abstract Alditols (“sugar alcohols”, “glycitols”) form palladium(II) complexes in neutral aqueous solution if they can provide the threitol partial structure. This requirement excludes erythritol, ribitol, and allitol when applied to the common tetritols, pentitols, and hexitols. The remaining alditols are able to arrange their threo ‐tetraol‐O 4 pattern to an almost planar rhomb, to which four Pd II N 2 (N 2 =bidentate nitrogen ligand) centres bind in a butterfly‐shaped Pd 4 motif. Bridging is the exclusive bonding mode of the four alkoxido donors. In contrast to the butterfly complexes, all alditols are able to form a species at a pH intermediate between neutrality and the stronger alkaline conditions of non‐bridging diolato‐palladium(II) binding, namely, the μ‐triolato bonding mode. A Pd 2 (μ‐triolato) unit shows the middle O atom of a propanetriolato fragment as a bridging ligator, with the lateral O atoms binding in the terminal mode.