Premium
Dynamic nuclear magnetic resonance of zinc and cadmium complexes of 1,2‐propanediaminetetraacetic acid
Author(s) -
Li Fei,
Song Ruifang
Publication year - 1991
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260290718
Subject(s) - chemistry , nitrogen inversion , zinc , nitrogen , cadmium , spectral line , methyl group , atmospheric temperature range , reaction rate constant , nmr spectra database , kinetics , group (periodic table) , organic chemistry , thermodynamics , physics , quantum mechanics , astronomy
The 1 H NMR temperature dependence of the zinc(II) and cadmium(II) complexes of 1,2‐propanediaminetetraacetic acid (1,2‐PDTA) was investigated. The four AB patterns in the 1 H NMR spectra of the acetates of the complexes were assigned with the aid of computer‐simulated spectra at various temperatures. The AB interchange phenomena due to nitrogen inversion were observed in the temperature range 90–148°C. The rate constants and the activation parameters were calculated. It is shown that the nitrogen‐inversion rates of the two asymmetric nitrogen atoms are different, both for Zn(1,2‐PDTA) 2− and for Cd(1,2‐PDTA) 2− , and that those of the nitrogen atom on the same side as the methyl group are slower. A water displacement mechanism in the process of nitrogen inversion is proposed on the basis of the kinetic data.