Science
Related: About this forumPolymers of Cerium and Plutonium.
The paper I'll discuss in this post is this one: Monomers, Dimers, and Helices: Complexities of Cerium and Plutonium Phenanthrolinecarboxylates (Albrecht-Schmitt* et al Inorg. Chem., 2016, 55 (9), pp 43734380)
Recently in this space, I discussed, based on my knowledge of plutonium chemistry, that polymers of cerium also exist, since cerium is often utilized in the lab as a plutonium analogue: Cerium Requirements to Split One Billion Tons of Carbon Dioxide, the Nuclear v Solar Thermal cases.
As the year wound down, I decided to burn up the remaining unused "free" literature downloads connected with my ACS membership - we get 50 free papers per year with our membership - since all the major libraries were closed for the holidays. My search term was to search for recent papers in ACS journals with "plutonium" in the title.
And low and behold, I came across a paper on cerium polymers investigated along with plutonium polymers, a paper focusing on the validity of the "close analogue" association connected with the two elements.
From the introduction:
...To further understand the convergence and divergence in the reaction chemistry between cerium and plutonium complexes and better characterize the viability of using CeIV as a nonreactive analogue of PuIV, the mixed N- and O-donor 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) was chosen as a complexant. The tetradentate PDA ligand is exceptionally suited for comparative studies with f elements. For example, many lanthanide- and actinide-containing PDA complexes have been prepared that demonstrate the ability of PDA to provide a suitable coordination environment for large, trivalent, oxophilic ions.(16-22) PDA has also provided a platform to interrogate f-element electronic structure and bonding in EuIII and TbIII complexes through sensitization studies of EuIII luminescence(18) and to evaluate the differences in the thermodynamics of complexation with the early actinides ThIV,(19) UVI,(19) and NpV.(20) This ligand is additionally attractive given that it, as well as its derivatives, are being investigated for use in the separation of americium and curium from lanthanides in advanced nuclear fuel cycles.
Apparently the plutonium in the complexes is in the +4 oxidation state, also accessible to cerium:
The complexity of the redox chemistry of plutonium is unparalleled by any other element. This makes the oxidation state assignment challenging, particularly from visual coloration alone. There are, for instance, blue compounds containing PuIV,(24, 25) although this color is normally indicative of PuIII. Likewise, PuIV complexes yield a variety of colors, with red and green being most common.(4-6) Mixtures of oxidation states are more common than not for plutonium in solution but quite rare in the solid state because crystallization is always under solubility control and may or may not reflect the dominant species in solution.(26, 27) Fortunately, the fingerprint spectra of intra-f transitions for plutonium in different oxidation states have been well established for decades, and identification of the formal charge from electronic absorption spectra is relatively straightforward, particularly in solids.(4-6) The reaction of PuIII with PDA results in the formation of a solid with a golden color that is not clearly indicative of any particular oxidation state. However, both the absorption spectrum and structural data are consistent with PuIV (vide infra), and the compound has the straightforward formulation of 3.
Plutonium is, by the way, unparalleled by any other element and in my less than humble opinion, is the key element for saving the world, despite a lot of tripe about how unacceptably "dangerous" it is.
A photograph of crystals of plutonium and cerium complexes described in this paper:
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"3" is the plutonium PDA complex, Pu(PDA)2 the other two are cerium complexes. (PDA = 1,10-phenanthroline-2,9-dicarboxylic acid)
Some other graphics from the text:
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In their discussion the authors show that the assumption of identity in the chemistry of cerium and plutonium often does not hold. Here is the UV/Vis spectra of the analogues:
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Some magnetic and thermal properties:
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The conclusion of the paper:
This may all seem very esoteric, and in my previous post I argued that cerium based carbon dioxide splitting can never address the bulk of the climate change problem should future generations need to clean up our mess to simply survive, but I personally believe that thermochemical splitting can participate in the clean up.
The existence of cerium polymers, particularly as organics that can be grafted easily onto supports may serve in greatly improving the mass efficiency of cerium for this purpose, should it ever become feasible to so use cerium.
I wish you the happiest and healthiest New Year.
ROB-ROX
(767 posts)The decay of Pu may have an affect with the polymer? Selecting a more stable isotope like Pu - 239 versus Pu - 242 would be interesting. The University of California has an interesting nuclear chemistry group at LLL(Lawrence Livermore Lab), LBL(Lawrence Berkeley Lab), and LAL (Los Alamos Lab)
NNadir
(33,541 posts)...is quite near bomb grade, 94% 239Pu, 6% 240Pu, described in the paper thusly:
I'd guess that this plutonium may have been rejected for the synthesis of nuclear weapons on a quality control basis, but I'm not sure of that.
It would be better of course, to be less complicated with radiation effects to do this work with mature plutonium that was highly enriched in 242Pu, although I would think that the largest inventory of this type of material is probably in France. In saying this, I am assuming that the French have reprocessed twice through Pu from used MOX fuel. It would need to have decayed long enough to minimize the presence of Pu-241, which probably doesn't survive all that well in MOX in any case.
I assume that the synthetic experiments in this paper were performed at Los Alamos since the experimental section includes the following text:
Other labs, with the exception of that at Stanford, are clearly analytical labs, National High Magnetic Field Laboratory, Tallahassee, Florida and George L. Clark X-ray Facility & 3M Materials Laboratory, University of Illinois, Urbana-Champaign.
Berkeley was Glenn Seaborg's "home" institution, and to my knowledge still has one of the best radiochemical labs and nuclear engineering departments in the country, despite the fact that the state as a whole is an anti-nuke hellhole that apparently would rather burn from excess dangerous fossil fuel waste than get serious about climate change and "re-embrace" nuclear energy.
It's kind of tragic actually, shitting on Seaborg's legacy in California, and definitely recalls the horrible situation in Germany, another gas dependent anti-nuke hellhole, where a leading actinide/nuclear chemistry facility is at Karlsruhe.