About the Project
Background
The f block is vital to modern society. The 4f (lanthanide) elements lie at the heart of many key technologies, e.g. phosphors and lighting (europium); high-strength magnets for electronics, hybrid vehicles and wind turbines (neodymium); optoelectronics (neodymium, erbium); magnetic resonance imaging (gadolinium); automobile catalytic converters (cerium). The 5f (actinide) series features two elements (uranium and plutonium) that are central to nuclear power production. We need to know as much as we possibly can about the chemistry of these fascinating elements.
This PhD project will employ computational quantum chemistry based on density functional and ab initio wavefunction theories to gain detailed understanding of the electronic structure and bonding in molecules containing f elements. The computational chemistry of the f block remains challenging, for two principal reasons: (i) relativistic effects (the modification of atomic orbital energies vs non relativistic analogues, and spin-orbit coupling) - which can either be neglected or accommodated with only simple approximations and corrections for light atoms - have a significant effect on 4f and 5f element chemistry, and must be explicitly included in calculations, and (ii) the near degeneracy of several sets of valence atomic orbitals (e.g. for the actinides 5f, 6d, 7s and 7p) can lead to a plethora of closely-spaced electronic states which pose formidable electron correlation challenges. In this project you will learn how modern computational chemistry can overcome these challenges, and apply your skills to cutting edge problems in molecular f element chemistry.
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
The initial project
Generally accepted wisdom holds that, while the chemistry of the early actinides has certain characteristics in common with the d transition elements (e.g. a range of accessible oxidation states, a degree of covalency to the bonding), that of the later actinides resembles the lanthanides, i.e. a dominant +3 oxidation state and ionic bonding. The evidence for this view of later actinide chemistry is, however, limited, as these elements are highly radioactive and experimental studies are fiendishly tricky. Heroic recent studies, however, have extended the chemistry of the actinides into the latter half of the series, with surprising conclusions. In particular, work by Albrecht-Schmitt et al. [Nature Communications 6 (2015) 6827] on compounds of californium has suggested that the +2 oxidation state may be more accessible than previously thought, and that covalency may play a significant role in californium’s chemistry. Furthermore, these authors conclude “We predict that complexes of einsteinium, fermium and mendelevium will show greater perturbations from their isoelectronic lanthanide analogues than even californium because of the increasing stability of the divalent state and the involvement of valence orbitals in bonding.”
I can confidently state that this prediction is unlikely to be experimentally tested anytime soon. Computational chemistry, however, is not limited by the experimental constraints, and the initial focus of this PhD position will be to assess the role of the +2 oxidation state and covalency in the chemistry of the later actinide elements, comparing them with their lanthanide equivalents. In particular, the energetics of the reactions
2 MX 3 → 2 MX 2 + X 2 (M = Gd-Lu, Cm-Lr; X = H, F-I, η ⁵ C 5 H 5 , other monovalent ligands…)
will be calculated, and the electronic structures of the metal containing species evaluated using modern quantum chemical analysis tools such as the quantum theory of atoms in molecules and natural bond orbital techniques. Other inorganic and organometallic compounds featuring the metals in the +2 oxidation state will also be studied.
The subsequent focus of the research is not fixed at this stage, giving the successful applicant the opportunity to develop and explore their own interests in molecular f element chemistry.
Qualification
Applicants should have or expect a good II(i) or 1st class honours degree (or an equivalent degree) in Chemistry or a related discipline.
Contact for further Information
Informal enquiries should be directed to Professor Nik Kaltsoyannis [Email Address Removed]
A formal application must be submitted to be considered for this project.
Research group website: http://www.mub.eps.manchester.ac.uk/kaltsoyannisgroup/
Centre for Radiochemistry Research website: http://crr.manchester.ac.uk/
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