H-1 NMR properties of trinuclear transition-metal complexes [M-3 O-square(OOCR)(6)L-3](+) (M = Cr, Fe, Mn; R = CH3, C2H5,CH2NH2; L = C5H5N, H2O)
- 化学化工－已发表论文 
A series of oxo-centered trinuclear transition-metal complexes with general formula [(M3O)-O-II(OOCR)(6)L-3](+) (M = Cr, Fe, Mn; R = CH3, C2H5, CH2NH2; L = C5H5N, H2O) were studied by H-1 NMR spectra. The investigation was focussed on the change of H-1 chemical shifts with various factors such as metals, ligands, temperatures and solvents. The experimental results show that the main effect on chemical shifts comes from skeleton metals and there is antiferromagnetic exchange interaction among the three metal ions within M3O core, For manganese complexes, the influence mechanisms of paramagnetic centers on chemical shifts and peak widths were discussed. It shows that their H-1 NMR isotropic shifts are mostly contributed by contact interactions.