The effects of axial interactions on electron paramagnetic resonance spectra of copper(II) chelates: weak complexes of copper(II) chelates and chloroform
- 1 January 1969
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc. A
- p. 545-550
- https://doi.org/10.1039/j19690000545
Abstract
X-Band e.p.r. spectra in chloroform–toluene glasses at 77°K show that chloroform forms weak complexes with some planar compounds of copper(II). Spin Hamiltonian parameters for some ‘isolated’ cupric chelates and for some corresponding chloroform–chelate complexes are reported, and these parameters are equated to the atomic orbital coefficients in some of the molecular orbitals involved in bonding in both types of compound. The relative ordering of the energies of the B2g and A1g levels in planar copper(II) compounds may change if the ligand is changed. Effects of axial perturbations which arise from two axial dipoles acting on planar cupric complexes are considered, and first-order perturbation theory is used to obtain relationships which connect the spin Hamiltonian parameters for the ‘isolated’ complexes with those for the perturbed complexes: experimental observations are in accord with the theoretical treatment. Relaxation arising from rotation about the long axis of these cupric complexes controls the line-widths in their e.p.r. spectra recorded at 295°K: the effect of chloroform complexing on paramagnetic relaxation phenomena in these complexes is noted. E.p.r. methods may be used to discriminate between different isomers of polyketone complexes of copper(II).Keywords
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