University of Illinois Urbana-Champaign

Electron Paramagnetic Resonances Studies of High Symmetry Molybdenum(v) and Solvent Effects of Square Planar Copper(ii) Complexes

Liczwek, Deborah Lynn

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Description

Title
Electron Paramagnetic Resonances Studies of High Symmetry Molybdenum(v) and Solvent Effects of Square Planar Copper(ii) Complexes
Author(s)
Liczwek, Deborah Lynn
Issue Date
1982
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
  • Frozen solutions of a series of Ca-S and Cu-O complexes; ('63)Cu(dtc)(,2), bis-diethyldithiocarbamato-copper(II), ('63)Cu(mnt)(,2)('-2), bis(1,2-dicyano-1,2-dithioethylene)cuprate(II), ('63)Cu(imnt)(,2), bis(1,1-dicyano-2,2-dithioethylene)cuprate(II), ('63)Cu(acac)(,2), bis(acetylacetonate)copper(II), ('63)Cu(dpm)(,2), bis(2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II), ('63)Cu(dbm)(,2), bis(1,3-phenyl-1,3-propanedionato)copper(II), ('63)Cu(bzac)(,2), bis(1-phenyl-1,3-butanedionato)copper(II) show highly solvent-dependent electron paramagnetic resonance spectra at (TURN)35, (TURN)9.5, and (TURN)3.7 GHz. The general increase of linewidth with frequency reveals the effects of g strain and the value of low-frequency EPR spectroscopy for frozen solutions. Simultaneous computer simulations of both the 9.5 and 3.7 GHz spectra were required for accurate spin-Hamiltonian parameters. Axial coordination by pyridine increases the copper nuclear quadrupole coupling interaction, in some cases, by an order of magnitude. The principal nuclear quadrupole coupling constant for all copper(II) compounds shows consistent behavior, increasing with symmetry of the coordination sphere, and pointing to a strong contribution of ligand charges to the effective field gradients.
  • Secondly, frozen solution EPR spectra of a monomeric molybdenum(V) complex, tetrakis(N,N-diethyldithiocarbamato)molybdenum(V)chloride show little or no nuclear quadrupole coupling effects as with the copper frozen solutions, simultaneous computer simulations of 35, 9 and 3 GHz spectra were computed for accurate determination of spin-Hamiltonian parameters. In the dodecahedral structure the molybdenum resides in a highly symmetric site. This complex suggests either an upper or lower bound for the correlation of site geometry with nuclear quadrupole coupling constants. This is discussed in the context of other nuclear quadrupole coupling constants for 3 other monomeric molybdenum(V) complexes.
  • The general increase in linewidth with frequency and nuclear states, m, reveals the effects of g strain and A strain, respectively. Attempt is made to correlate this to bonding interactions in the Mo(dtc)(,4) complex.
Graduation Semester
1982
Type of Resource
text
Permalink
http://hdl.handle.net/2142/70198

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