Lanthanides hydrothermal hydrolysis

Group IVB, actinide, and lanthanide, hydrothermal hydrolysis spectroscopic studies. 58-62... 

Group IVB, actinide and lanthanide hydrothermal hydrolysis (continued)... 

Hydrothermal hydrolysis of metal ions is useful in producing crystalline phases which contain metals in a state of partial hydrolysis, i.e., a state intermediate between that of the hydrated metal ion and that of the hydrous hydroxide. Such reactions have been used to produce numerous crystalline phases of actinides (1-4), Group IV metal ions (5-14) and lanthanides (15-21). 

Previous studies of the hydrothermal hydrolysis of tetravalent Th, U and Np (1-4) have shown a remarkable similarity in the behavior of these elements. In each case compounds of stoichiometry M(0H)2S0i, represent the major product. In order to extend our knowledge of the hydrolytic behavior of the actinides and to elucidate similarities and differences among this group of elements, we have investigated the behavior of tetravalent plutonium under similar conditions. The relationships between the major product of the hydrothermal hydrolysis of Pu(IV), Pu2(OH)2(SO.,)3 (H20) t, (I)> and other tetravalent actinide, lanthanide and Group IVB hydroxysulfates are the subject of this re-... 

Alternatively, hydrolysis of presumably not so soluble lanthanide carboxylate complexes may be possible by carrying out the hydrolysis under hydrothermal conditions. It appears that such conditions (high temperature and high pressure) are particularly conducive to the formation of polynuclear lanthanide complexes, often with unpredictable but nevertheless interesting structure. Under ambient pressure, analogous synthesis generally produces complexes with carboxylate coordination only and without any involvement of hydroxo groups. 

The hydrothermal synthesis of the hexanuclear core-based hydroxido-lanthanide coordination polymers, [R3(BDC)3 5(0H)2(H20)2] H20 (R = Y, Yb, and Er BDC = 1,4-benzenedicarboxylate) further attests the rmiqueness of hydrothermal procedures (Weng et al., 2006). The controlled hydrolysis of lanthanide ions led to an open hexanuclear cluster core, drastically different from the commonly observed cubane or octahedral-shaped cluster cores. The hexanuclear core contains six /i3-OH-bridged R(III) ions from two asymmetric imits and adopts a chair-like configuration (R = Y, Figure 102). This hexanuclear building block is linked by the BDC ligands to form a 3D framework. 

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