Solid-state spin-1/2 NMR studies of disorder, bonding, and symmetry

• Author / Creator

  Harris, Kristopher J.

• This thesis is concerned with applications of modern solid-state NMR spectroscopy. Investigations of three quite different types are undertaken, each of which attempt to advance knowledge in the fields of chemistry and NMR. The goal of each project is to obtain insight into the effects of chemical environment, in particular bonding, on the NMR observables.

  Carbon-13 and nitrogen-15 solid-state nuclear magnetic resonance has been used to study solid samples containing the dicyanoaurate(I) anion, [Au(CN)2]-, with n-butylammonium, potassium, and thallium counterions. Differences in Au-Tl metallophilic bonding are shown to cause a difference in the isotropic cyanide carbon-13 chemical shift of up to 15.7 ppm, while differences in Au-Au aurophilic bonding are found to be responsible for a change of up to 5.9 ppm. Disordered polymeric gold(I) monocyanide was also investigated, and a range of 7+-2% to 25+-5% of the AuCN chains are found to be "slipped" instead of aligned with the neighbouring chains at the metal position.

  An investigation of the chemical shift tensors of the 13C-labelled carbons in solid samples of Ph13C≡13CPh and (η2-Ph13C≡13CPh)Pt(PPh3)2·(C6H6) has also been carried out. Coordination of diphenylacetylene to platinum causes a change in the 13C chemical shift tensor orientation and a net increase in the isotropic chemical shift. The carbon chemical shift tensors in the platinum complex bear a striking similarity to those of the alkenyl-carbons in trans-Ph(H)C=C(H)Ph, and a theoretical discussion of these observations is presented.

  Each of the fundamental NMR interaction tensors (σ, J, D and V) may be decomposed into isotropic, symmetric, and antisymmetric components. Observations of all theoretically allowed components other than the antisymmetric portion of J (Janti) have previously been published. Andrew and Farnell's theory (Mol. Phys. 15, 157 (1968)) for the effects of Janti on NMR spectra has been extended to powdered samples, and methods for analyzing the resultant line shapes have been determined. Finally, the first reported experimental attempts to measure Janti are presented, and experimental proof that no elements of Janti(119Sn,119Sn) in hexa(p-tolyl)ditin are larger than 2900 Hz is given.

• Subjects / Keywords

  • MAS
  • Dewar-Chatt-Duncanson
  • MO
  • Antisymmetric
  • Cyanide
  • NMR
  • Shielding
  • Aurophilic
  • Solids
  • Alkyne
  • Coupling
  • Platinum
  • Tensors
  • Alkene
  • DFT
  • Gold

• Graduation date

  Fall 2009

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3S94M

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.