University of Illinois Urbana-Champaign

Studies of Nuclear Quadrupole Effects in Transition Metal Complexes by Electron Paramagnetic Resonance

Duliba, Edward Paul

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Description

Title
Studies of Nuclear Quadrupole Effects in Transition Metal Complexes by Electron Paramagnetic Resonance
Author(s)
Duliba, Edward Paul
Issue Date
1983
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Physical
Abstract
  • Predictions of the nuclear quadrupole coupling constants for octahedral copper(II) and the applicability of computer simulation methods to extract quadrupole coupling data from EPR of powders were confirmed with ('63)Cu and ('65)Cu doped into MgSO(,4)(.)7D(,2)O as a test case. From orientation-dependent EPR spectra of each isotope, both as oriented single crystals and as powders, the following spin-Hamiltonian is deduced for ('63)Cu: (')H = (beta) B(.)g(.)S(' )+(' )hI(.)A(.)S - g(,n) (beta)(,n) B(.)I(' )+(' )QD(I(,z)('2)-5/4) + QE(I(,x)('2)-I(,y)('2)).
  • The QD value is among the largest known for octahedral Cu(II), as is typical of the octahedral CuO(,6) grouping. For some magnetic field orientations, secondary ((VBAR)(DELTA)m(,I)(VBAR) = 1) and tertiary ((VBAR)(DELTA)m(,I)(VBAR) = 2) transitions are important and the primary ((DELTA)m(,I) = 0) transitions are strongly affected by quadrupolar effects. The powder and single crystal methods yield parameters in good agreement. Solutions of CuC(,20)S(,2)O(,2)H(,22) were also examined and the nuclear quadrupole coupling parameters determined.
  • The nuclear quadrupole coupling constants for a low-spin^square planar cobalt(II) compound were determined by EPR^spectroscopy. Oriented single crystals and powders of Co-^doped {(C(,2)H(,5))(,4)N}(,2)Ni(S(,2)C(,4)N(,2))(,2) were examined and their EPR^spectra interpreted with the following spin Hamiltonian: (')H = (beta) B(.)g(.)S(' )+(' )hI(.)A(.)S - g(,n)(beta)(,n)B(.)I(' )+(' )hQD(I(,z)('2)-63/4) + hQE(I(,x)('2)-I(,y)('2)). The quadrupole coupling parameters are compared with other available examples and the general absence of quadrupolar effects in the EPR of other low-spin cobalt(II) single crystals discussed. Two high-spin amino acids derivatives were also examined. The cobalt doped powder of the low-spin compound, Ni(amben), yielded measurable quadrupole coupling values. Several cobalt complexes, previously unexamined by EPR, were found not to produce EPR signals and are listed.
Graduation Semester
1983
Type of Resource
text
Permalink
http://hdl.handle.net/2142/70210

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