Nuclear Resonance Studies of Structural Equilibria in Solutions of Nickel(II) Complexes
Recent work (1–7) has demonstrated that in solutions of non-coordinating solvents certain general types of four-coordinate nickel(II) complexes undergo a rapid dynamic structural equilibrium between planar and tetrahedral confi — gurations. This existence of this equilibrium has already been demonstrated in the cases of bis(N, N-disubstituted-aminotroponeimine) (5), bis(N-substituted-salicylaldimine) (1, 2, 6), and bis(N-substituted-o-hydroxynaphthal - dimine) (3, 7) complexes. For these general types of complexes it has been shown (2 – 5) that an analysis of the isotropic proton hyperfine contact shifts (8) manifested in the nuclear magnetic resonance spectra leads to an evaluation of the thermodynamic parameters (ΔF, ΔH, ΔS) of the structural change, and to a determination of the spin density distribution in the π-system of the coordinated ligand.
KeywordsNuclear Magnetic Resonance Spectrum Spin Density Spin Density Distribution Molybdic Acid Hydrochloric Acid Medium
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