On the basics of carbohydrate-metal chemistry: complexes of palladium(II) with hydroxyaldehyde and -ketone hydrates.

In this work, we present novel complexes of hydroxyaldehydes and ketones with palladium(II). The compounds are studied by two-dimensional NMR spectroscopy in solution (COSY, HMQC, HMBC). Glycolaldehyde, d-glyceraldehyde, glyoxal and 2,4-O-ethylidene-d-erythrose were used as aldehydes, d-erythrulose was used as an alpha-hydroxyketone. Although different species are present in solution, only the hydrated forms of the aldehydes can coordinate to the metal centre. These complexes are stable at 4 degrees C in aqueous solution. The crystal structure of a complex formed by mesoxalic acid and palladium(II) is reported and shows coordination by both hydroxy groups of the hydrated ketone.