Using the PPN (PPN = bis(triphenylphosphine) iminium) salt of tetrametaphosphate, [P4O12]4–, first reported by Ishii and coworkers, we prepared a corresponding crystalline salt of the oxyacid dihydrogen tetrametaphosphate [H2P4O12]2−. The latter has a molecular structure in which the diacid dianion benefits from double intramolecular hydrogen bond stabilization; pKa measurements indicate that the diacid dianion has an acidity intermediate between that of trifluoroacetic acid and acetic acid in acetonitrile solution. Dehydration of the diacid dianion using DCC afforded a crystalline PPN salt of the corresponding anhydride, [P4O11]2−. The latter is under investigation as a chemical phosphorylating agent with new results to be discussed. Dihydrogen tetrametaphosphate, by virtue of its acidity, is effective at protonating away basic ligands from metal complexes to result in new metal complexes of tetrametaphosphate. For example, reaction with titanyl acetylacetonate gave rise to dimeric titanyl tetrametaphosphate, having terminal titanyl groups, with release of acetylacetone. Dimeric metal tetrametaphosphate complexes have been obtained in analogous fashion for vanadium, chromium, and molybdenum. Efforts to extend the [M2(P4O12)2]4− motif to later transition metals, (Ru, Pd) and to new systems containing the terminal metal oxo functional group, will be described.

Metaphosphates: Avenues enabled by new reagents and starting materials

255th National Meeting (2018)

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