Oxoanions and Related Species

Phosphorus.—Oxoanions and Related Species. Ab initio and semi-empirical molecular orbital calculations on the metaphosphate anion [PO3]- attribute the electrophilic reactivity of this species to a low-lying acceptor orbital of a symmetry, nearly degenerate with a n molecular orbital. This species, metaphosphate, is suggested as intermediate in one of the two pathways involved in phosphorylation by phosphorocreatine. Kinetic isotope effect studies indicate that metaphosphate is also generated in the hydrolysis of 2,4-dinitrophenylphosphate  

For the hydrolysis of the triesters (RO)oP(0)OAr [equation (19)] there is a buffer-catalysed reaction. The data do not distinguish between an addition-elimination 

Measurements of the heat of hydrolysis of P(OEt)g yield free energies of formation of P(OEt) (OH)6-n. Calculation of free-energy changes for the addition of water to phosphoric acid and its esters, and comparison with kinetic data on the hydrolysis of these esters, indicates that there are high barriers to the breakdown of five-coordinate intermediates in phosphoryl transfer reactions. A value of 32 kcal mol is deduced for AG for the dehydration of H3PO4 to HPOs.  

As usual there have been a number of papers on the hydrolysis of polyphosphates. Complexes of [VO] + or [VO] + with polyphosphates give species in which phosphate hydrolysis is much more rapid than for the uncomplexed species. We may also note the appearance of further evidence that the oxidation reactions of peroxodiphosphate involve hydrolysis in the rate-determining stage. Studies on the oxidation of antimony(iii), hydrazine, nitrite, and hypophosphite have appeared.  

A very interesting synthetic reaction, which can be understood in terms of mechanistic ideas, is the synthesis of (RO)sP from elementary white phosphorus and the alkoxide ion  

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Phosphorus.—Reactions of oxoanions and related species, phosphorus-oxygen-nitrogen compounds, phosphazanes, and other components and intramolecular processes are considered in this section. 

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