Aqueous co-ordination chemistry using electrospray mass spectrometry of anions: metal(VI)-monosaccharide complexes (M = W or Mo)

Electrospray mass spectrometry has been applied for the first time to the co-ordination chemistry of aqueous anions, using as a model system the reaction of tungstate or molybdate with galactaric (mucic) acid and galacturonic acid; 1 : 1, 2: 1 and 1 :2 complexes are found, thus confirming and extending previous solution-state studies. The gas-phase ions may undergo minor dehydration, and some decarboxylation. Nevertheless, the method is shown to provide a rapid and simple means for identifying mixtures of anionic complexes in dilute aqueous solution, even when their binding constants are modest.