NNadir
NNadir's JournalReaching the end of a job interview, the Human Resources Manager asked the young engineer...
...fresh out of the university, , "And what starting salary were you looking for?"
The engineer said, "In the neighborhood of $100,000 a year, depending on the benefit's package."
The HR Manager said, "Well, what would you say to a package of $200,000 a year, 5 weeks vacation, 14 paid holidays, full medical and dental, company matching retirement fund to 50% of salary, and a company car leased every 2 years - say, a red Mercedes?"
The engineer sat up straight and said, "Wow!!! Are you joking?"
And the HR Manager said, "Of course, ...but you started it."
You know what happened to the relationship between Lise Meitner and Otto Hahn?
If you get right down to the nucleus of their relationship, well, they split.
A string theorist's husband walks in on his wife in bed with another man.
She yells, "I can explain everything!"
Polymers 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.
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