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Updated: May 20, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Carbohydrate chelation in neutral aqueous solution: the threo-tetritolato-Pd(4) butterfly motif
Thorsten Allscher1, Peter Klüfers
1Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 Munich, Germany.
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.
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