The Electron Spin Resonance Spectrum of Copper-Doped Palladium bis-Benzoylacetonate Crystals

  • Michael A. Hitchman
  • R. Linn Belford


The EPR spectrum of about 0.5% Cu2+ diluted into the two crystalline forms of Pd bis-benzoylacetonate is reported. The spectrum of the (\(11\bar{1}\)) face of the needle modification shows an anomalous doubling of the EPR lines which is explained by the presence of twinning in this crystallographic form. The principal g values and directions have been obtained in terms of an arbitrary molecular coordinate system using a specially written computer program. The following parameters result: gx = 2.0490; gy = 2.0478; gz = 2.2428; A = −181 x 10−4 cm−1, B = − 28 x 10−4 cm −1; with the in-plane g axes lying approximately between, rather than along, the copper-oxygen bonds. These results are used to estimate bonding parameters for the molecule. For comparative purposes bonding parameters for Cu bis-acetylacetonate have been recalculated from the EPR data of Maki and McGarvey using recent estimates of the d-level energies. While the σ-bonding molecular orbital coefficients are almost the same in the two chelates, both the in-plane and out-of-plane π-bonding coefficients are significantly smaller in the complex with the phenyl-substituted ligand. The orientation of the g tensor implies that the along-the-bonds rhombic effect of the phenyl groups does not affect the orientation of the (xz) and (yz) orbitals, and causes ho significant contamination of the ground-state orbital by the (3z2r2) orbital, which can therefore be ignored in deriving the covalency parameters.


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Copyright information

© Plenum Press, New York 1969

Authors and Affiliations

  • Michael A. Hitchman
    • 1
  • R. Linn Belford
    • 1
  1. 1.Noyes Chemical Laboratory and Materials Research LaboratoryUniversity of IllinoisUrbanaUSA

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