Phosphate compounds, bidentate

Bidentate phosphate compounds. The organophosphorus bidentate extractants are neutral species extractants that undergo no keto-enolization and have no exchangeable hydrogens (as is the case in extraction by the bidentate diketones). They contain either two P=0 groups or one P=0 and one C=0 group. The carbamoylmethyl-phosphonates (CMPs) and carbamoylphosphonates (CPs) are examples of the latter, while the tetraalkyldiphosphonates and tetraalkyl-diphosphinedioxides [or bis-(disubstituted phosphinyl)-alkanes] are examples of the former. 

The organophosphorus bidentate octaethyltetraamidopyro-phosphate (OETAPP), a compound of the type R.2P(0)NH(0)PR.2, is noted for the extraction of uranium from HC1 as well as HNO3. 

In Table 20.10 are listed the actinide phosphate and arsenate compounds whose structures have been determined. All of these structures involve the tetrahedral XOl ion in mono- and bidentate linkages to actinide ions. 

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