Tetra actinide compound

The tetrakis(dialkylphosphido) complexes, An(PPP)4 (An = Th, U) PPP = P(CH2CH2P(CH3)2), were prepared by reacting AnC with four equivalents of the lithium or potassium salt of the PPP tetra-anion. The stmcture of these compounds shows triangulated dodecahedra distorted toward bicapped trigonal prisms. These complexes represent one of the first actinide systems containing exclusively metal-phosphorus bonds. These complexes are known to undergo insertion reactions as seen in actinide amido compounds. ... 

The most promising actinide squestering agents yet prepared (Table IX) are the sulfonated catechoylamide derivatives of linear tetra-amines. These compounds appear to strongly bind tetravalent actinides, while only weak complexation has been observed for trivalent and divalent metals. A derivative of the natural product spermine, 3,4,3-LICAMS, is more effective in plutonium removal at low dosages than any other sequestering agent tested to date. 

Siddall has pioneered the use of N, N disubstituted amides as extractants for tetra- and hexavalent actinides. The carbonyl oxygen in these compounds has enhanced basicity because of the presence of the amido nitrogen, and therefore should be analogous to the neutral organo-phosphorous compounds in extraction properties. 

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