G. N. Mar
Mar 1, 1969
Citations
0
Influential Citations
10
Citations
Journal
Journal of Magnetic Resonance
Abstract
Abstract The PMR spectra for the acetylacetone protons in di-adducts of bis(acetylacetonate) complexes of cobalt(II) and nickel(II) with various coordinating solvents, M(II) (AA)2·2L, have been recorded. For the nickel complexes, the observed contact shifts are independent of L. The isotropic shifts for the cobalt adducts represent both contact and dipolar interactions, where the magnitude of the dipolar contribution is a very sensitive function of the chemical nature of coordinating solvent, such that some adducts display either primarily contact or dipolar shifts. The opposite signs for the dipolar shifts for the L and AA protons confirm the trans configuration for these adducts. For the complexes with nitrogen donor atoms, the dipolar shifts are proportional to magnetic anisotropy, which increases with decreasing ligand field strength of L. For the cobalt adducts, the methyl linewidths for the N-bonded ligands decrease with increasing magnetic anisotropy, indicating an electronic relaxation mechanism involving interaction with low-lying excited states.