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Experimental and Computational Magnetic Resonance Studies of Selected Rare Earth and Bismuth Complexes
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. (Chemistry of Interfaces)ORCID iD: 0000-0001-9577-6845
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The rare-earth elements (REEs) and bismuth, being classified as the ‘most critical raw materials’ (European Raw Materials Initiatives, 2017), have a high economic importance to the EU combined with a high relative supply risk. REEs are highly important for the evolving technologies such as clean-energy applications, high-technology components, rechargeable batteries, permanent magnets, electric and hybrid vehicles, and phosphors monitors.This scientific research work aims at building a fundamental knowledge base concerning the electronic/molecular structure and properties of rare-earth element (REE) and bismuth complexes with dithiocarbamate (DTC) and 1,10-phenanthroline (PHEN) by employing state-of-the-art experimental techniques such as nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction (XRD) techniques together with ab initioquantum mechanical computational methods. This combination of methods has played a vital role in analysing the direct and significant effect of the heavy metal ions on the structural and magnetic resonance properties of the complexes, thereby, providing a framework of structure elucidation. This is of special importance for REEs, which are known to exhibit similar chemical and physical properties. The objectives of the work involve i) a systematic investigation of series of REE(III) as well as bismuth(III) complexes to get a profound understanding of the structure-properties relationship and ii) to find an appropriate theoretical modelling and NMR calculation methods, especially, for heavy metal systems in molecular and/or solid-state. This information can later be used in surface interaction studies of REE/bismuth minerals with DTC as well as in design and development of novel ligands for extraction/separation of metal ions.The REE(III) and bismuth(III) complexes with DTC and PHEN ligands have all provided aunique NMR fingerprint of the metal centre both in liquid and solid phase. The solid-state 13C and 15NNMR spectra of the diamagnetic REE(III) and bismuth(III) complexes were in accord with their structural data obtained by single crystal XRD. The density functional theory (DFT) methods were used to get complementary and refined structural and NMR parameters information for all diamagnetic complexes in the solid-state. The relativistic contributions due to scalar and spin-orbit correlations for the calculated 1H/13C/15N chemical shifts of REE complexes were analysed using two-component zeroth-order regular approximation (ZORA)/DFT while the ‘crystal-lattice’ effects on the NMR parameters were calculated by combining DFT calculations on molecular and periodic solid-state models. The paramagnetic REE complexes display huge differences in their 1H and 13C NMR spectral patterns. The experimental paramagnetic NMR (pNMR) chemical shifts, as well as the sizable difference of the 1H and 13C NMR shifts for these isoelectronic complexes, are well reproduced by the advanced calculations using ab initio/DFT approach. The accuracy of this approach is very promising for further applications to demanding pNMR problems involving paramagnetic f-block elements.The results presented in this thesis demonstrate that a multidisciplinary approach of combined experimental NMR and XRD techniques along with computational modelling and property calculations is highly efficient in studying molecular complexes and solids containing heavy metal systems, such as rare-earths and bismuth.

Place, publisher, year, edition, pages
Luleå University of Technology, 2017.
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Chemical Sciences Physical Sciences
Research subject
Chemistry of Interfaces
Identifiers
URN: urn:nbn:se:ltu:diva-65378ISBN: 978-91-7583-947-9 (print)ISBN: 978-91-7583-948-6 (electronic)OAI: oai:DiVA.org:ltu-65378DiVA, id: diva2:1136508
Public defence
2017-09-29, C305, Luleå tekniska universitet, Luleå, 10:00
Supervisors
Available from: 2017-08-29 Created: 2017-08-28 Last updated: 2018-06-05Bibliographically approved
List of papers
1. DFT calculations in the assignment of solid-state NMR and crystal structure elucidation of a lanthanum(iii) complex with dithiocarbamate and phenanthroline
Open this publication in new window or tab >>DFT calculations in the assignment of solid-state NMR and crystal structure elucidation of a lanthanum(iii) complex with dithiocarbamate and phenanthroline
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2016 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, no 48, p. 19473-19484Article in journal (Refereed) Published
Abstract [en]

The molecular, crystal, and electronic structures as well as spectroscopic properties of a mononuclear heteroleptic lanthanum(iii) complex with diethyldithiocarbamate and 1,10-phenanthroline ligands (3 : 1) were studied by solid-state 13C and 15N cross-polarisation (CP) magic-angle-spinning (MAS) NMR, X-ray diffraction (XRD), and first principles density functional theory (DFT) calculations. A substantially different powder XRD pattern and 13C and 15N CP-MAS NMR spectra indicated that the title compound is not isostructural to the previously reported analogous rare earth complexes with the space group P21/n. Both 13C and 15N CP-MAS NMR revealed the presence of six structurally different dithiocarbamate groups in the asymmetric unit cell, implying a non-centrosymmetric packing arrangement of molecules. This was supported by single-crystal X-ray crystallography showing that the title compound crystallised in the triclinic space group P1[combining macron]. In addition, the crystal structure also revealed that one of the dithiocarbamate ligands has a conformational disorder. NMR chemical shift calculations employing the periodic gauge including projector augmented wave (GIPAW) approach supported the assignment of the experimental 13C and 15N NMR spectra. However, the best correspondences were obtained with the structure where the atomic positions in the X-ray unit cell were optimised at the DFT level. The roles of the scalar and spin-orbit relativistic effects on NMR shielding were investigated using the zeroth-order regular approximation (ZORA) method with the outcome that already the scalar relativistic level qualitatively reproduces the experimental chemical shifts. The electronic properties of the complex were evaluated based on the results of the natural bond orbital (NBO) and topology of the electron density analyses. Overall, we apply a multidisciplinary approach acquiring comprehensive information about the solid-state structure and the metal-ligand bonding of the heteroleptic lanthanum complex.

National Category
Physical Chemistry
Research subject
Chemistry of Interfaces
Identifiers
urn:nbn:se:ltu:diva-61144 (URN)10.1039/c6dt03705d (DOI)000390470400035 ()27891541 (PubMedID)2-s2.0-85002666619 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2016-12-19 (andbra)

Available from: 2016-12-19 Created: 2016-12-19 Last updated: 2018-06-05Bibliographically approved
2. Structural insights into the polymorphism of bismuth(III) di-n-butyldithiocarbamate by X-ray diffraction, solid-state (13C/15N) CP-MAS NMR and DFT calculations
Open this publication in new window or tab >>Structural insights into the polymorphism of bismuth(III) di-n-butyldithiocarbamate by X-ray diffraction, solid-state (13C/15N) CP-MAS NMR and DFT calculations
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2017 (English)In: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 129, p. 123-132Article in journal (Refereed) Published
Abstract [en]

Two crystalline polymorphs of a binuclear tris(di-n-butyldithiocarbamato)bismuth(III) complex, I and II, with an empirical formula of [Bi{S2CN(n-C4H9)2}3] were synthesised and characterised by X-ray diffraction (XRD), solid-state NMR and density functional theory (DFT) calculations. At the supramolecular level, these mononuclear molecular units interact in pairs via secondary Bi⋯S bonds, yielding binuclear formations of [Bi2{S2CN(n-C4H9)2}6]. The polymorph I () contains two isomeric non-centrosymmetric binuclear molecules of [Bi2{S2CN(n-C4H9)2}6], which are related to each other as conformers, therefore having four structurally inequivalent bismuth atoms and twelve inequivalent dithiocarbamate ligands. In contrast, the structurally simpler polymorph II (P21/n) exists as a single molecular form of the corresponding centrosymmetric binuclear formation, comprising two structurally equivalent bismuth atoms and three structurally different dithiocarbamate groups. The polymorphs I and II were found to be interconvertible by altering the solvent system during the recrystallisation process. Sun et al. (2012) has reported a crystalline form of the title compound which resembles, but is not identical with, polymorph II. Experimental solid-state 13C and 15N cross-polarisation (CP) magic-angle-spinning (MAS) NMR spectra of both polymorphs I and II were in accord with the direct structural data on these complexes. Assignments of the resonance lines in the solid-state 13C and 15N NMR spectra were assisted by chemical shift calculations of the crystals using periodic DFT.

National Category
Physical Chemistry
Research subject
Chemistry of Interfaces
Identifiers
urn:nbn:se:ltu:diva-62688 (URN)10.1016/j.poly.2017.03.018 (DOI)000401382500017 ()2-s2.0-85017200488 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-04-12 (rokbeg)

Available from: 2017-03-27 Created: 2017-03-27 Last updated: 2018-06-05Bibliographically approved
3. Structure Elucidation of an Yttrium Diethyldithiocarbamato-Phenanthroline Complex by X-ray Crystallography, Solid-State NMR, and ab-initio Quantum Chemical Calculations
Open this publication in new window or tab >>Structure Elucidation of an Yttrium Diethyldithiocarbamato-Phenanthroline Complex by X-ray Crystallography, Solid-State NMR, and ab-initio Quantum Chemical Calculations
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2016 (English)In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, Vol. 20, p. 3278-3291Article in journal (Refereed) Published
Abstract [en]

We present a structural analysis method for molecular and electronic structure of yttrium diethyldithiocarbamato-phenanthroline complex {[Y(S2CNR2)3PHEN] with R = C2H5 and PHEN = 1,10-phenanthroline} combining solid-state NMR spectroscopy, XRD, and first principles DFT calculations. Replacing the Nd3+ ion with Y3+ in the reported crystal structure of [Nd(S2CNR2)3PHEN] complex generated an approximate 3D structure of the title complex. The structure was then subjected to first principles quantum chemical geometry optimisation using periodic DFT method. The quality of the method is discussed by comparing predicted and experimental powder XRD patterns. Full assignment of 13C and 15N solid-state CP-MAS NMR spectra as well as analyses of the principal values of the chemical shift tensors were carried out using periodic scalar relativistic DFT modelling. Spin-orbit relativistic effects, estimated by SO-ZORA formalism for one molecular unit, were evaluated. Finally, the X-ray structure of the title complex was determined, which proved that the former procedure is appropriate. The most important orbital interactions were investigated by Natural Bond Orbital analysis. The isotropic shielding values for S2CN-carbons were analysed by Natural Localised Molecular Orbital analysis. The present approach can be further extended to study other rare earth metal complexes, particularly those having similar but not yet solved crystal structures

National Category
Physical Chemistry Other Physics Topics
Research subject
Chemistry of Interfaces; Tillämpad fysik
Identifiers
urn:nbn:se:ltu:diva-15691 (URN)10.1002/ejic.201600059 (DOI)f3cebb95-1de1-4acf-b56e-aebed545a76c (Local ID)f3cebb95-1de1-4acf-b56e-aebed545a76c (Archive number)f3cebb95-1de1-4acf-b56e-aebed545a76c (OAI)
Note
Validerad; 2016; Nivå 2; 20160615 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-06-05Bibliographically approved

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